USGS Research on Energy Resources-1986 

Program and Abstracts 

V. E. McKelvey Forum 

on Mineral and Energy 

Resources 

U.S. GEOLOGICAL SURVEY CIRCULAR 974 
WEST EAST 

lit lia Jlin Jt 

Cover.- Oblique aerial photographic view within Snake River Range northwestward toward Starvation Peak, Teton County, Wyoming, showing asymmetrical anticline in the Absaroka thrust sheet. Shape of fold and its structural 

setting are similar to those in the Ryckman Creek, Clear Creek, and Painter 

Reservoir fields producing oil and gas in southwesternmost Wyoming. Original 

color slide by S. S. Oriel, 1981. 

Sketch of geology in the area: core of Starvation Peak anticline consists of 

lower Mesozoic Woodside Red Beds ('Rw), flanked by Thaynes Limestone ('Rt), 

Ankareh Red Beds, ('Ra), Nugget Sandstone (J'Rn) and Twin Creek Limestone 

(Jt). Twin Creek Limestone on east flank of anticline has been thrust northeast 

over Cretaceous Frontier (Kf) and Aspen (Ka) Formations along Absaroka 

thrust fault. Twin Creek on west flank of anticline is overridden by eastwardthrust Pennsylvanian quartzites of the Wells Formation (PIPw) and the Perrnian Phosphoria Formation (Pp) at base of St. John thrust sheet. Farther west, 

Triassic units ('Rd, Dinwoody Formation) in upper part of St. John sheet are 

overridden by Pennsylvanian Wells quartzite along base of Thompson Peak 

thrust sheet; tightly folded strata of this sheet are in turn overridden by rocks 

above Dry Elk Canyon fault. Sketch by A. L. Isom from geology by S. S. 

Oriel and others. 
USGS Research on Energy Resources-1986 

Program and Abstracts 

Edited by L. M. H. Carter 

V. E. McKelvey Forum 

on Mineral and Energy 

Resources 

U.S. GEOLOGICAL SURVEY CIRCULAR 974 
Department of the Interior 

DONALD PAUL HODEL, Secretary 

U.S. Geological Survey 

Dallas L. Peck, Director 

Organizing Committee for the 1986 McKelvey Forum: 

Martin B. Goldhaber, Chairman 

Lorna Carter 

Romeo M. Flores 

Karen J. Franczyk 

Donald B. Hoover 

Samuel Y. Johnson 

Judith Totman Parrish 

C. Wylie Poag 

J o Ann Schnepf 

Parke D. Snavely, Jr. 

Free on application to Distribution Branch, Text Products Section, 

U.S. Geological Survey, 604 South Pickett Street, Alexandria, VA 22304 

1986 
A society's wealth depends on the use it makes 

of raw materials, energy, and especially ingenuity 

-V. E. McKelvey 

III 
FOREWORD 

Dallas l. Peck, Director, U.S. Geological Survey 

The extended abstracts in this volume are summaries of the papers presented 

orally and as posters in the second V. E. McKelvey Forum on Mineral and 

Energy Resources, entitled "USGS Research on Energy Resources-1986." 

The Forum has been established to improve communication between the USGS 

and the earth science community by presenting the results of current USGS 

research on nonrenewable resources in a timely fashion and by providing an 

opportunity for individuals from other organizations to meet informally with 

USGS scientists and managers. It is our hope that the McKelvey Forum will 

help to make USGS programs more responsive to the needs of the earth science 

community, particularly the mining and petroleum industries, and Win foster 

closer cooperation between organizations and individuals. 

The Forum was named after former Director Vincent E. McKelvey in recognition of his lifelong contributions to research, development, and administration 

in mineral and energy resources, as a scientist, as Chief Geologist, and as 

Director of the U.S. Geological Survey. The Forum will be an annual event, 

and its subject matter will alternate between mineral and energy resources. 

We expect that the format will change somewhat from year to year as various 

approaches are tried, but its primary purpose will remain the same: to encourage direct communication between USGS scientists and the representatives 

of other earth-science related organizations. 

Energy programs of the USGS include oil and gas, coal, geothermal, uranium-thorium, and oil shale; work in these programs spans the national domain, 

including surveys of the offshore Exclusive Economic Zone. The topics selected 

for presentation at this McKelvey Forum represent an overview of the scientific breadth of USGS research on energy resources. They include aspects of 

petroleum occurrence in Eastern United States rift basins, the origin of magnetic anomalies over oil fields, accreted terranes and energy-resource implications, coal quality, geothermal energy sources, integrated geology and chemistry in uranium-deposit studies, and interpretations of sea-floor geology seen 

in reconnaissance-scale sidescan-sonar mosaics of the Gulf of Mexico and west 

coast Exclusive Economic Zone. Data are presented that are being used in 

building models of geothermal energy settings, basin histories, and the occurrence of energy resources. In addition to the technical sessions presenting the 

results of USGS research, each congressionally mandated USGS Mineral Resource Program has a display outlining plans and progress. 

We are all excited about this continuing opportunity to disseminate and discuss our research with our colleagues in industry and academia, and we welcome your suggestions on improving this series of Forums. 

IV 
SECOND ANNUAL V. E. McKELVEY FORUM-PROGRAM 

OF LECTURES AND DISCUSSIONS 

Wednesday, February 5, 1986 Taphonomy of nonmarine mollusks as an indicator of alluvial-lacustrine seiimentation John H. Hanley 

andRomeoM. Flo·res 

8:15a.m. 

10:10a.m. 

10:30a.m. 

12:00noon 

2:00p.m. 

-Session I (Grand Ballroom, Regency 

Hotel) 

Terry W. Offield and Robert M. Hamilton, presiding 

Opening remarks Robert M. Hamilton 

An approach to integrated sedimentary 

basin analysis 

Arthur G-reen, keynote speaker 

Terranes, resources, and the geodynamics of continental growth 

David G. Howell andDavidL. Jones 

Paleoceanographic and tectonic influences 

on the deposition of the Monterey FormationofCalifornia JohnA. Barron 

-Coffee break (Rotunda) 

-Session I continued (Grand Ballroom) 

Thomas D. Fouch, presiding 

Uranium ore genesis in the context of basin 

evolution, SanJuan Basin, New Mexico 

Christine E. Tu:rner-Peterson and NeU 

S.Fishman 

Uranium-bearing solution-collapse breccia 

pipes in northern Arizona 

Karen We·nrichandGeorgeH. 

Billingsley 

Geothermal systems in the Cascade Range 

Michael£. So·rey, Steven E. lngebritsen, 

and Robert H. Mari·ne·r 

Reservoir fluids of the Baca, New Mexico, 

geothermal field A. H. Truesdell 

and C. J. Janik 

-Luncheon honoring Vincent E. McKelvey 

(Grand Salon) 

Luncheon address by Raymond A. Price 

"Cordilleran accretionary tectonics, the 

overthrust belt and energy resources-A 

Canadian perspective" 

-Session II (Grand Ballroom) 

H.J. Gluskoter, presiding 

Allocyclic and autocyclic conditions of coal 

formation C. Blaine Cecil 

Depositional controls on the geometry of the 

Wyodak-Anderson coal bed, northeastern Wyoming Pete1·D. Warwick 

and Ronald W. St.anton 

v 

3:20p.m. 

3:50p.m. 

New approach to organic geochemical 

studies of the coalification rrocess--

Chemical and physical evohtion of 

coalified logs as a function of rank 

Patrick G. Hatcher 

-Coffee break (Rotunda) 

-Session II continued (Grand Ballroom) 

L. J. Patrick Muffler, presiding 

Structure and petroleum potential of 

Palisades Roadless Area, Idah'J-Wyoming thrust-belt salient near Jackson, 

Wyoming StevenS. Oriel 

an.dDavidW. Moore 

Burial history and timing of thermal gas generation in Cretaceous rocks, eastern 

Uinta Basin, Utah-Eviden~e from 

Lopatin reconstruction 

Janet K. Pit·man and Karen J. Fra·nczyk 

Evolution of oil-shale basins-Evidence 

from sulfur geochemistry M. L. Tuttle 

and M. B. Goldhaber 

Fluid migration pathways-Evidence from 

thermal maturity mapping in scuthwestern Wyoming B. E. Law, 

M. R. Lickus, and M. J. PawleuJicz 

7:30-lO:OOp.m. -Keg and poster session (Ballroom and 

Rotunda) 

Thursday, February 6, 1986 

8:30a.m. -Session III (Grand Ballroom) 

Dudley D. Rice, presiding 

GLORIA sidescan-sonar survey of the 

Western Mississippi Fan intrll.slope basins B.A. McG-regor, J. S. Schlee, 

andK. D. Klitgard 

Seismic structure and stratigrap~y of the 

Western Florida Shelf 

M ahlon M. Ball and JimLeinb,:wh 

Structural development of the sou~heastern 

margin of the Anadarko basin, Oklahoma 

WilliamJ. Perry, Jr. 
10:10a.m. 

10:30a.m. 

PROGRAM OF LECTURES AND DISCUSSIONS (CONTINUED) 

Thermal maturity modeling and geochemical 

characterization of hydrocarbon source 

rocks, oils, and natural gases of the 

Anadarko basin J. R. Hatch, 

D. D. Rice, R. C. Burruss, 

J. W. Schmoker, andJ. L. Clayton 

Petroleum generation and migration in 

Lower Jurassic lacustrine sequences, 

Hartford basin, Connecticut and Massachusetts Lisa M. Pratt, 

AprilK. Vuletich, and Robert C. 

Burruss 

-Coffee break (Rotunda) 

-Session III continued 

Dudley D. Rice, presiding 

VI 

Marine cementation and errly porosity loss 

in bank-margin carborates-Examples 

fromEnewetak RobertB. Halley, 

EugeneA. Shinn, andLarryA. Beyer 

Magnetic minerals and hydrocarbon seepage-Possibilities for m::tgnetic detection 

of oil fields Rich,-,,rd L. Rey'nolds, 

NeilS. Fishman, MarkR. Hudson, 

J. A. Karachewski, and Martin B. 

Goldhaber 

Advances in understandinr North Slope oil 

and gas accumulations K. J. Bird, 

L. B. Magoon, and C. M. Molenaar 

Gas hydrates, North Slope of Alaska 

T. S. Collett, K. J. Birc!, L. B. Magoon, 

K. A. Kvenvolden, and G. E. Claypool 

Future hydrocarbon studies in the Bering 

Sea AlanK. Cooper, 

MichaelS. Marlow, andDavidW. Scholl 
SECOND ANNUAL V. E. McKELVEY FORUM-POSTER SESSIONS 

Booth Oil and Gas, Regional Geology, Marine Geology 

Accretion, subduction, and underplating in southern Alaska: Initial results from the 

Trans-Alaska Crustal Transect 

Robert A. Page, David L. Campbell, George Plafker, Gary S. Fuis, Warren T. 

Nokleberg, Elizabeth L. Ambos, Walter D. Mooney, and Michael A. Fisher 

2 Geomorphology of the Western United States Exclusive Economic Zone-A 

GLORIA view 

EEZ-Scan Group (David A. Cacchione, David E. Droke, Brian D. Edwa·rds, 

Michael E. Field, James V. Gardner, Monty A. Hampton, Herman A. Ka·rl, 

DavidS. McCulloch, Neil H. Kenyon, and Douglas G. Masson) 

3 GLORIA sidescan-sonar survey of the Western Mississippi Fan intraslope basins 

B. A. McG-regor, J. S. Schlee, andK. D. Klitgord 

4 Expert systems research and its application to energy studies 

Katherine B. Krystinik 

5 The U.S. Geological Survey Oil Shale Program 

Thorn.as D. Fouch and John R. Dyni 

6 Organic carbon accumulation and sulfur diagenesis in fine-grained Cretaceous rocks of 

the Western Interior ofN orth America 

Donald£. GautierandLisa.M. Pratt 

7 Stratigraphic and structural framework, southern terminus of Rocky Mountains 

E l·mer H. Baltz 

8 Geometry and hydrocarbon appraisal of the Putnam thrust adjacent to the Snake River 

Plain near Blackfoot, Idaho 

KarlS. Kellogg,FrankR. Hladky, and George A. Desbomugh 

9 Thermal maturity mapping of the United States 

JmnesG. Palacas 

10 Classification of clastic reservoirs for enhanced oil recovery 

C. J. Schenk, J. W. Schmoker, and D. L. Gautier 

11 U.S. Geological Survey Onshore Oil and Gas Program 

Dudley D. Rice 

12 An integrated approach using the computer in the geologic assessment of the hydrocarbon resource of the Powder River Basin, Wyoming and Montana 

Richa·rdF. Mast, James E. Fox, andGordonL. Dolton 

13 Three statistical methods for estimating undiscovered resources based on the Minnelusa 

play, Powder River Basin 

J. Houghton, E. Attanasi, G. Dolton, L. Drew, R. Mast, D. Root, a'nd J. 

Schuenemeye-r 

14 Fracture network flow 

Christophe·rC. Barton 

15 Evaluating compositional trends in Miocene-Pliocene strata of south-central coastal 

California 

Caroline M. Isaacs, Kathleen C. Stewart, and Larry L. Jackson 

16 The U.S. Geological Survey Evolution of Sedimentary Basins Program 

Thonws D. Fouch, B. H. Kent, J. W. Schmoker, J. L. Ridgley, K. J. Englund, and 

K.J.Bird 

VII 
POSTER SESSIONS (CONTINUED) 

17 An application of azimuthal vertical seismic profiles 

M. W.Lee 

18 The Shublik Formation-A model for deposition in an ancient marine upwelling zone 

Judith Totman Parrish 

19 Geochemical study of surface oil shows and potential source rocks in the Arctic N atiom.l 

Wildlife Refuge (North Slope Alaska) 

DonaldE. Anders and Leslie B. Magoon 

20 Regional correlation sections across theN orth Slope of Alaska 

C. M. Molen .aar, K. J. Bird, and T. S. Collett 

21 Conodont thermal maturation patterns in Paleozoic and Triassic rocks, northern 

Alaska-Geologic and exploration implications 

Anita G. Harris, I. L. Tailleur, and H. RichardLane 

22 Tectonics-A first-order control of sediment distribution and hydrocarbon potential: Examples from the western margin ofN orth America 

ThomasJ. Wiley 

23 Tectonics and the potential for hydrocarbons in offshore basins of Western North 

America 

Hugh McLean 

24 Analysis of seismic reflection lines over Pacific convergent margins 

J. J. MillerandR. E. vonHuene 

25 Potential gas generation in subducted sediments of the eastern Aleutian Trench area 

RolandvonHuene 

26 Continental margin mapping project, United States Atlantic margin-A synthesis of 

geological and geophysical data and interpretations 

Kim D. Klitgord and Gary H. Hill 

27 USGS multichannel seismic-reflection profile 25--A stratigraphic reference section fC'r 

the Baltimore Canyon trough 

C. WyliePoaga-ruiJohnA. Grow 

28 Windows in the Pulaski thrust sheet and their implications for hydrocarbon potential 

along part of the eastern Appalachian overthrust province 

Arthur P. SchultzandDonaldE.Anders 

29 Thermal evolution of kerogen and phytoclasts in the Eastern United States early 

Mesozoic basins as a guide to maturation 

R. K. Kotra, R. M. Gottfried, E. C. Spiker, P. G. Hatcher, and A. J. Froelich 

Coal and Peat 

30 Discriminant analysis of trace elements in coal beds of Early and Middle Pennsylvanian 

age from the central Appalachian basin 

J. T. O'Connor 

31 Stable isotope geochemistry of calcite and pyrite in the upper Freeport coal bed, westcentral Pennsylvania 

C. Blaine Cecil, Frank T. Dulong, Joseph F. Whelan, Ronald W. Stanton, and Elliot 

C. Spiker 

32 Trace-element associations in coals of the Eastern United States 

C. A. Palmer, P. C. Lyons, andZ. A. Brown 

33 Laser microprobe "fingerprinting" and origin of elements in vitrite bands from selected 

coal beds of Eastern United States 

Paul C. Lyons, John J. Mo·relli, David M. He·rcules, Curtis A. Palmer, Floyd W. 

Brown, Janet D. Fletche·r, a-ruiMartaR. Krasnow 

VIII 
POSTER SESSIONS (CONTINUED) 

34 Sulfur hexafluoride gas as a stable tracer of geological and geochemical processes: Application to the energy industry and earth sciences 

J. R. Herring and G. M. Reimer 

35 Enhanced analysis of trace-element characteristics of bituminous coals using the proton 

(PIXE) microprobe 

JeanA. Minkin, E. C. T. Chao, and Henna Blank 

36 Petrologic study of the characteristics of coals of autochthonous and allochthonous origin 

E. C. T. Chao, Jean A. Minkin, JudithM. Back, andSharonS. Crowley 

37 Pyrite of transported origin in reworked fragments from the I coal bed of the Upper Cretaceous Ferron Sandstone Member of the Mancos Shale, central Utah 

E. C. T. Chao, JudithM. Back, andJeanA. Minkin 

38 Sequential tectonics of the western margin of the Powder River Basin, Johnson and 

Sheridan Counties, Wyoming 

E. Neal Hinrichs 

39 Allocyclic controls on thick coal deposition in sedimentary basins-Some Powder River 

Basin examples 

BionH. Kent, Frances Wahl Pierce, Carol£. Molnia, andEdwardA. Johnson 

40 Ground-water composition as an indicator of sodium content in coal in the Powder River 

Basin, southeastern Montana and northeastern Wyoming 

Ricky T. Hildebrand 

41 Sedimentology and tectonic setting of intermontane Tertiary coal-bearing rocks, southwestern Montana 

J. M'Gonigle, M. Kirschbaum, arulJ. Weaver 

42 The U.S. Geological Survey Coal Resources Program 

H. J. Gluskoter 

43 Computerized assessment of the coal resources and geology of the San Juan Basin, New 

Mexico 

Carol L. Molnia, Antoinette L. Medlin, Kathleen K. Krohn, Joseph T. O'Connor, 

Laura H. Bie'wick, Nancy K. Ga,rdner, and Lewis W. Boger 

44 Geochemical characterization of selected coals from the Beluga energy resource area, 

south-central Alaska: Site of a proposed coal mine 

Gary D. Stricker, Ronald H. Affolter, arul Michael E. Brownfield 

45 Nanushuk Group coal investigations-North Slope of Alaska 

E. G. Sable, G. D. Stricker, andR. H. Affolte,r 

55 Prospecting deposits for peat resources in the United States 

Cornelia C. Ca,meron 

56 Low-ash synthetic fuel from lignite, peat, or sewage sludge 

Frank E. SenftleandPriscillal. Hackney 

Uranium 

46 An exploration model based on a genetic model for the tabular-type vanadium-uranium 

deposits in the Henry basin, Utah 

H. Roy Northrop, Fred Peterson, Gene Whit'ney, andMartinB. Goldhaber 

47 The formation and alteration of tabular-type uranium-vanadium deposits as a variant of 

normal diagenetic processes in organic-rich sediments 

CharlesS. SpirakisandPaulaL. Hansley 

48 Genesis and identification of the Colorado Plateau Uranium Province 

Harry C. Granger, Warren I. Finch, Fred Peterson, Morris W. Green, Richard F. 

Sanford, C. S. Bromfield, and F. Allan Hills 

IX 
POSTER SESSIONS (CONTINUED) 

49 The use of mineral alteration patterns and stable isotope compositions to infer a paleo} 7'-

drologic regime 

Gene Whitney, H. Roy Northrop, andPaulaL. Hansley 

50 Geochemical processes affecting the zonation of vanadium, iron, and chromium, and implications for vanadium-uranium ore formation in the Colorado Plateau 

Richard B. Wanty, George N. Breit, and Martin B. Goldhaber 

51 Geology and geochemistry of the Precambrian rocks of the Reading Prong, New York 

and New Jersey-Implications for the genesis of iron-uranium-rare-earth depos;~s 

Linda C. Gundersen 

52 Controls on distribution of ore in so-called "unconformity-type" uranium deposits in Australia and implications for United States uranium resources 

C. J. Nutt, David Frishman, R. /. Grauch, J. T. Nash, andK. R. Ludwig 

53 The U.S. Geological Survey Uranium and Thorium Program 

Thomas D. Fouch and Jennie L. Ridgley 

54 Movement and fixation of uranium on organic matter in a late Quaternary uranium deposit, Stevens County, Washington 

Jam-es K. Otton and Robert A. Zielinski 

Geothermal 

57 Geopressured-geothermal energy potential-1986 

Raymond H. Wallace, Jr. 

58 Thermal-energy storage in a confined sandstone aquifer at St. Paul, Minnesota 

R. T. Miller 

59 Borehole geophysical applications in the characterization of geothermal energy resourc~s 

F. L. Paillet, R. H. Mo·rin, andW. S. Keys 

60 The U.S. Geological Survey Geothermal Research Program 

L. J. Patrick MufflerandManuelNathenson 

61 Geothermal significance of an extensive conductor beneath Newberry Volcano, Oregon 

D. V. Fittennan, R. J. Bisdorf, W. D. Stanley, and A. A. R. Zohdy 

62 Medicine Lake Volcano, California, and its geothermal potential 

JulieM. Donnelly-Nolan 

63 Prospecting for shallow magma chambers in the Cascade Range using seismic tomography 

JohnR. Evans, Douglas A. Staube·r, and Phillip B. Dawson 

64 Induced seismicity and the state of stress at The Geysers geothermal area, California 

D. H. Oppenheinzer 

65 The Salton Sea Scientific Drilling Program-A progress report 

J. H. Sass, J.D. Hendricks, S. S. Priest, andL. C. Robison 

X 
GRAND BALLROOM 

~ 

25 ... m m 42 

20UJ33 34w41 

24 

27rn32 35rn40 

43 

23 

28rn31 36m39 44' 

22 

29ill3o s1])38 45 

21 

20 

15rn14 9rn8 

19 

16rn13 10rn7 

17rn12 1 1rn 6 

FLOOR PLAN 

3 

2 

REGISTRATION 

LOBBY 

ROTUNDA 
Abbreviations used in this Circular: 

EEZ-Exclusive Economic Zone 

Ga-giga-annum (109 years ago) 

Ma-mega-annum (106 years ago) 

m.y.-106 years duration 

STP-standard temperature and pressure 

TCF -trillion cubic feet 

bbl-barrel 

In the term GLORIA sidescan system, GLORIA stands for Geological Long-Range Inclined Asdic 

The use of trade names in this report is for descriptive purposes only and does not imply endorsement by the U.S. Geological Survey. 

XII 
V. E. McKelvey Forum on Mineral and Energy Resources 

USGS Research on Energy Resources-1986 

Program and Abstracts 

Edited by L. M. H. Carter 

GEOCHEMICAL STUDY OF SURFACE OIL 

SHOWS AND POTENTIAL SOURCE ROCKS IN 

THE ARCTIC NATIONAL WILDLIFE REFUGE 

(NORTH SLOPE ALASKA) 

Donald E. Anders and Leslie B. Magoon 

The presence of six oil seeps or oil-stained outcrops in the Arctic National Wildlife Refuge 

(ANWR) of northeastern Alaska indicates the possibility of commercial hydrocarbon occurrence in 

the subsurface. Interest in the resource potential 

of this region is heightened by the fact that 

ANWR is flanked by two important petroleum 

provinces, the Prudhoe Bay area on the west (estimated in-place reserves of 40--70 billion barrels 

of oil), and the McKenzie delta on the east (estimated in-place reserves of 740 million barrels). 

These productive areas adjacent to ANWR have 

quite different geology from each other, including 

different sources and geochemical character of 

their respective hydrocarbons. These differences 

make it impossible to extrapolate the geologic and 

geochemical relationships of the adjoining regions 

into the coastal plain of ANWR. 

Organic carbon content, Rock-Eval pyrolysis, 

and vitrinite reflectance were used to evaluate the 

source rock quality and thermal maturity of five 

rock units within ANWR-the Shublik Formation, 

Kingak Shale, pebble shale, and bentonite and 

shale in the Colville Group. The average organic 

carbon content within these rock units is as follows: (1) 1.6 weight percent for the Triassic Shublik Formation; (2) 2.0 weight percent for the Jurassic and Lower Cretaceous Kingak Shale; (3) 3.0 

weight percent for the Lower Cretaceous pebble 

shale; ( 4) 4. 0 weight percent for the bentonite section of the Upper Cretaceous Colville Group; and 

1 

(5) 2.0 weight percent for the Tertiary shale sequence and shale of the Upper Cretaceou-;, Colville 

Group. The Cretaceous rock units in A1 rwR are 

thermally immature (vitrinite reflectance <0.5 

percent) with respect to hydrocarbon g~neration 

on the coastal plain and thermally mature to overmature (vitrinite reflectance > 1.0 percent) in the 

Sadlerochit and Shublik Mountains, where tectonic events have brought more deeply buried 

rocks to the surface. Rocks older than C:-:-etaceous 

do not crop out in the coastal plain of Ar TWR and 

could not be evaluated. The oils collected from immature rocks in the coastal plain presum~.bly migrated from a mature source. 

In ANWR, organic matter type in the Tertiary 

section, the Lower Cretaceous pebble s"'lale, and 

the Lower Cretaceous rocks of the upper unit of 

the Kingak Shale is predominantly type. III (hydrogen index range 11-69 mg S2/gC); whereas, the 

organic matter in the Lower Cretaceous bentonite-rich zone equivalent to part of the Colville 

Group is predominantly type II. The organic-matter type in the Jurassic unit of the lower Kingak 

Shale and the Triassic Shublik Format~')n could 

not be reliably determined because the only samples available for study (from the Sadler')chit and 

Shublik Mountains) are thermally overmature. 

Based on comparison of the following r~ochemical attributes-stable carbon isotope ratios, tricyclic terpane ratios, pentacyclic:tricyclic terpane 

ratios, and saturate:aromatic hydrocarbon ratios, 

the ANWR oils can be divided into thre~ genetic 

oil types, typified by (1) the oils fron Augun 

Point, north and south Katakturuk River, and 

J ago River; (2) the oils from Manning F oint; and 

(3) the oil from Kavik. 

Oil-source rock correlation studies c f carbon 

isotope ratios, tricyclic terpane ratios, and pen-
tacyclic:tricyclic terpane ratios suggest that the 

most promising source rock for the Augun Point, 

Katakturuk River, and Jago River oil types is the 

type II bentonite unit equivalent to part of the 

Colville Group. Geochemically, the Manning Point 

and Kavik oil types are sufficiently different than 

the bitumens extracted from the five rock units 

assessed in this study so as to suggest sources 

that have not yet been evaluated. 

Given the foregoing similarity of the organic 

matter in the Colville Group bentonite to the oils 

from Jago River, Katakturuk River, and Augun 

Point, inference can be made that stratigraphic 

traps within the Colville Group, such as the finegrained lenticular turbidite sands, may have some 

limited reservoir potential, but the thicker Tertiary fluvial and marine sandstone sequences of 

the delta facies may be more favorable exploration 

targets. 

SEISMIC STRUCTURE AND STRATIGRAPHY 

OF THE WESTERN FLORIDA SHELF 

Mahlon M. Ball and Jim Leinbach 

The U.S. Geological Survey has obtained 3,000 

km of multichannel seismic-reflection data on the 

western Florida Shelf as part of its regional stratigraphic and structural framework studies in 

offshore territorial waters. These seismic lines 

were positioned to tie offshore well control to onshore wells in Florida and to the seismic network 

of the University of Texas (Texas Institute of 

Geophysics, Austin) over the deep Gulf Basin. The 

study reconciles offshore reflection data and well 

control with previous work based on onshore well 

studies and on gravity and magnetic data. 

The definition of geologic "basement" is especially important in understanding the structure of 

the western Florida Platform. Onshore drilling in 

Florida, reported by R. S. Barnett in 1975, reveals a variety of basement rocks. These basement-rock types have been projected into the 

offshore largely on the basis of similar gravity and 

magnetic characteristics and trends, as noted by 

K. D. Klitgord and others in a 1984 study. Basement blocks are inferred to be bounded by (1) 

northwest-trending fracture zones that were 

transform faults during the Late Jurassic opening 

of the Gulf of Mexico and (2) northeast-trending 

2 

hinge zones that separate rifted and intruded 

basement from relatively unfaulted continental 

blocks, as noted by K. D. Klitgord and others, 

in 1984. The rifted and intruded basement corresponds to transitional crust, tends to be structurally low, and is overlain by Mesozoic sedimentary 

basins. 

Similar characteristics are sugge~ted by the 

available seismic data. The seismic "basement" 

varies with changes in the magnetic and gravity 

data. In the northwest, relatively flat reflections 

from strata of the Mesozoic Apalachicola basin are 

separated by a prominent unconformity from more 

steeply dipping strata that are probably synrift 

in origin. A large basement fault inferred to represent a downdip continuation of the Gulf Basin's 

marginal fault zone is located at the n 'lrthwestern 

extension of the Bahamas Fracture Zone. Toward 

the southeast, the reflection markin~ the basement-sediment contact rises onto the Middle 

Ground Arch. This reflection fades as velocity and 

density contrasts diminish between tl' ~ onlapping 

Upper Jurassic strata and underlyirg Paleozoic 

sedimentary rocks. The apparent relief of the Middle Ground Arch in seismic-reflectior sections is 

enhanced by the regional southeastward velocity 

increase in the Mesozoic sediments overlying the 

Paleozoic basement. This increase is a result of 

a decrease in clayey sediments that predominate 

in the Apalachicola basin and an incre~se in dense 

limestones, dolomites, and anhydrite in the Mesozoic sediments of the Florida carbonate province. 

Seismic sections crossing the Florida Platform escarpment demonstrate the shallowing of basement 

beneath the platform relative to that under the 

deep Gulf Basin. 

The Apalachicola basin apparently contains a 

substantial thickness of Louann Salt. Our lines reveal an essentially flat basement ·reflection passing 

beneath an inferred salt pillow at Destin Dome. 

The dome is a northwest-trending anticline more 

than 80 km long and 30 km wide; it has relief of 

a kilometer on Lower Cretaceous rocks. The dome 

appears to be the result of a swell that was uplifted during the Late Cretaceous and early Cenozoic. Several smaller apparent salt swells with 

earlier growth histories than that of the Destin 

Dome are also present in Apalachicok basin. The 

Destin Dome has been and remains a petroleum 

exploration target with substantial potential. 
To the southeast, in the Florida carbonate province, local structures consist of low-relief platform-interior patch reefs that are similar to the 

oil-producing structures of the Lower Cretaceous 

Sunniland Limestone trend. Regional erosional 

highs such as the Sarasota Arch are also present, 

but they are poorly defined by the seismic records. 

Velocity surveys and lithologic descriptions 

from 4 key wells together with suites of sonic and 

density logs from 25 wells and the multichannel 

reflection lines connecting the key wells can be 

used to generate synthetic seismograms and to 

achieve optimum integration of the seismic and 

subsurface data. This approach is the basis for our 

correlation of basement, the top of the salt where 

present, the top of the N eocomian, the mid-Cretaceous unconformity, and the Cretaceous top 

throughout most of the western Florida Shelf 

north of lat 27° N. 

STRATIGRAPHIC AND STRUCTURAL 

FRAMEWORK, SOUTHERN TERMINUS OF 

ROCKY MOUNTAINS, NEW MEXICO 

Elmer H. Baltz 

The Sangre de Cristo uplift of New Mexico and 

Colorado is the southernmost range of the Rockies, lying between the northern basins of the 

Neogene Rio Grande rift and the Laramide-age 

Raton and Las Vegas basins of the Great Plains. 

Within this structurally complex uplift, Precambrian, Mississippian, and Pennsylvanian rocks are 

exposed widely; Permian, Mesozoic, and Cenozoic 

rocks and sediments are exposed on its margins; 

and Cenozoic volcanic and intrusive rocks occur 

at places on the uplift and its margins. The structure and stratigraphy of the uplift and its bordering basins in New Mexico are being studied by 

detailed and reconnaissance mapping, biostratigraphy, subsurface methods, and analyses of regional gravity and aeromagnetic data. The studies, 

especially of Pennsylvanian rocks, suggest the 

existence of potential hydrocarbon sources and 

structural and stratigraphic traps. 

In Pennsylvanian and Early Permian time the 

area of the present uplift, from about Taos, N. 

Mex., southward, and the area of the adjacent Las 

3 

Vegas basin were parts of a deep structural basin 

in which synorogenic fine-grained to gravelly 

sandstone, thick gray shale, and carbonate rocks 

were deposited in complexly related mar'le and 

nonmarine environments. The Pennsylvanian 

rocks are absent locally at the south but are almost 7, 000 ft thick at the north, both at o·1tcrops 

and in the subsurface. The thickening is accompanied by pronounced regional and local facies 

changes. Mapping of lithostratigraphic and biostratigraphic units shows that the Pennsylvanian 

rocks can be subdivided into regionally persistent 

formations useful for determining Paleozoic and 

Cenozoic structure and useful for integrati'lg regional surface and subsurface data to understand 

Paleozoic facies distribution. Newly recognized 

inter- and intraformational unconformities demonstrate several large Paleozoic, sediment-sh~dding, 

intrabasinal uplifts and complementary loc"<)l sedimentary basins. Isopachs of several formatjons reveal the correspondence of some Paleozoic and Cenozoic local uplifts and synclinal basins ani some 

faults; however, some exposed Paleozoic structures extend eastward into the subsurface of the 

Las Vegas basin. Pennsylvanian rocks on th~ west 

margin of the Sangre de Cristo uplift nm~h and 

south of Santa Fe are scant remnants of th'lse deposited on the flank of a major Paleozoic uplift 

that is now the western part of the Cenozoic uplift. Pennsylvanian rocks of several facies may 

thicken westward from the uplift into the subsurface of the Neogene Espanola Basin. 

Theories of origin of the Cenozoic Sangre de 

Cristo uplift include: (1) vertical uplift along downward-steepening reverse faults; (2) volc?notectonic uplift; and (3) several to several tens of miles 

of thin-skinned overthrusting. Detailed rrapping 

shows that the Cenozoic southeastern front of the 

uplift is a zone of northerly-trending, bas~mentcored, asymmetric, east-verging, anticlinal blocks. 

North of Las Vegas, for at least 30 mi, th~ eastern parts of these blocks were thrust ea <;'\tward 

across the mainly overturned west limb of the Las 

Vegas basin along probable listric faults. The vertical separation on the top of the Precambrian between the Las Vegas basin and the frontal zone 

of the Sangre de Cristo uplift is about 5,000 ft 

at the south and about 15,000 ft at the north. 

Horizontal shortening at the south is about 3,000 

ft and possibly more than 10,000 ft locally at the 

north near Mora, N. Mex. 
The Cenozoic overthrusting probably created 

lengthy structural traps on the west margin of the 

Las Vegas basin in areas where Pennsylvanian 

rocks contain thick, potential hydrocarbon source 

rocks interlayered with potential reservoir rocks. 

In some places the Cenozoic structure may have 

enhanced preexisting Paleozoic traps. Untested 

stratigraphic traps probably exist on other margins of the Las Vegas basin. 

PALEOCEANOGRAPHIC AND TECTONIC 

INFLUENCES ON THE DEPOSITION OF THE 

MONTEREY FORMATION OF CALIFORNIA 

John A. Barron 

A combination of oceanographic conditions and 

tectonic events shaped the deposition of the Monterey Formation, of Miocene age, the major petroleum source rock in California. The well-known 

abundant diatomaceous rocks in the Monterey are 

indicators of high biologic productivity, and 

diatoms may well be the original source for much 

of the petroleum of the Monterey. The biogenicrich sediments of the Monterey are relatively free 

of detrital mineral grains, and closely resemble 

pelagic sediments of the deep sea. 

The base of the Monterey at 17.5 Ma (late early 

Miocene) coincided with rising global sea level and 

with an increase in diatomaceous sediments 

throughout the North Pacific. The increase in 

biosiliceous sediments in the Pacific paralleled a 

decline in biosiliceous sediments in the Caribbean 

and low-latitude North Atlantic, which may have 

been caused by increased production of North Atlantic Deep Water in the latest early Miocene. 

With rising sea level, terrigenous sediments became largely isolated in inshore basins, while 

offshore basins received a steady rain of diatoms 

settling down from productive surface waters. 

Carbon isotope records in the Pacific and Indian 

Oceans record the storage of organic-rich sediments in the Monterey and equivalent diatomaceous rocks around the rim of the North Pacific by 

4 

a pronounced + 1.0 %o increase in B13C beginning 

at 17.5 Ma. 

Polar cooling in the late middle Mi 1cene and late 

Miocene was reflected by increased diatom productivity in the upper part of the Monterey, resulting from increased upwelling, in turn due to 

intensified circulation. Diatom fertility was high 

enough during the latest Miocene that the CCD 

(Calcium Carbonate Compensation D~th) was 

raised considerably, and upper Monterey rocks 

are essentially barren of foraminifer~, 

The top of the Monterey at about 6 Ma coincides 

with a major drop in sea level anc1 is commonly 

marked by an unconformity. Sediments above the 

Monterey have an increased terrigenous component, presumably because lowered sea level resulted in channels being cut throug'-1 to the outer 

basins, which allowed the transpm·t of detritus. 

Carbon isotope records in the Pacific and Indian 

Oceans show a -1.0 %o shift in &13C at 6.2 Ma, 

signalling an end to the vast storage of organicrich sediments in marginal reservoirs such as the 

Monterey. 

The Monterey Formation was also influenced by 

tectonic events during its deposition. Initiation of 

transform faulting and extension along the 

California margin in the latest Oligo~ene and early 

Miocene caused the subsidence of br~ins that later 

received Monterey sediments. A major tectonic 

event at about 10-9 Ma, which included rotation 

of the Santa Barbara Basin and a change in Pacific 

plate rotation, is marked by an unconformity and 

(or) an interval of compressed sed:ment in most 

Monterey sections. Another change in plate motion at about 6 Ma may be expressei by the angular discordance seen between the Monterey and 

overlying rocks. 

FRACTURE NETWORK FLOW 

Christopher C. Barton 

Fracture traces exposed on six 205- to 1, 726-m2 

laterally separated, subhorizontal pavements in 

the same shallow-dipping Miocene ash-flow tuff at 
South-southeast side of South Sister, Oregon, as viewed from across Sparks Lake. Photograph by Lyn Topinka, David A. 

Johnston Cascades Volcano Observatory, Vancouver, Wash., October 1984. 

Yucca Mountain, southwestern Nevada, have 

been mapped at a scale of 1:50. The maps are twodimensional sections through the three-dimensional network of strata-bound fractures. All fractures with trace lengths greater than 0.20 m were 

mapped. The distribution of fracture-trace lengths 

for all the pavements combined is log-normal. The 

fractures for all the pavements combined do not 

exhibit well-defined sets based on orientation. 

Fractal characterization (from a 1982 study of 

B. B. Mandelbrot) of such complex fracture-trace 

networks may prove useful for modeling fracture 

flow and mechanical responses of fractured rock; 

therefore, an analysis of each of the six maps was 

5 

done to test whether such networks are fractal. 

These networks proved to be fractal, and the fractal dimensions (D) are tightly clustered (1.10 to 

1.18), even though visually the fracture networks 

appear quite different. An electric analog of a 

fracture network (see a 1985 study of P. R. 

LaPointe and J. A. Hudson) with a fractal dimension that we determined to be D=1.39 has a 

strongly directed flow anisotropy, a characteristic 

that is not obvious from the distribution of fracture strikes. The fractal analysis also indicates 

that the network patterns are self-similar (scale 

independent) over two orders of magnitude for 

trace lengths ranging from 0.20 to 25m. 
ADVANCES IN UNDERSTANDING NORTH SLOPE 

OIL AND GAS ACCUMULATIONS 

K. J. Bird, L. B. Magoon, and C. M. Molenaar 

The North Slope of Alaska petroleum province 

is an onshore-offshore region of complex geology 

covering an area of more than 100,000 mi2 

(260,000 km2). Twenty-five oil and gas fields with 

in-place resources totaling more than 60 billion 

barrels of oil and 35 trillion cubic feet of gas have 

been discovered. Most North Slope oil and gas 

occur in a few large fields that are geographically 

concentrated within a relatively small area of the 

province, centered around Prudhoe Bay. The two 

producing fields, Prudhoe Bay and Kuparuk 

River, account for about 20 percent of daily 

United States oil production. 

Petroleum prospective rocks on the North Slope 

consist of a Mississippian to Lower Cretaceous sequence derived from a northern provenance and 

a Lower Cretaceous to Holocene successor basin 

sequence derived from a southern provenance. 

These sequences are deformed along a foreland 

fold and thrust belt to the south and are relatively 

undeformed along a passive margin to the north. 

Volumes of oil are nearly equally distributed in 

reservoirs of these two sequences of rocks. Regional analysis indicates that the time of generation 

and the location of most North Slope oil and gas 

fields were controlled by Cretaceous and Tertiary 

tectonics and sedimentation. 

Significant amounts of oil and gas are apparently yet to be discovered in this province, and 

most types of unconventional oil and gas resources 

are also present but as yet unevaluated; unconventional oil and gas resources include heavy oil 

or tar, oil shale, coalbed methane, tight gas sand, 

geopressured methane, and methane hydrates. 

Organic geochemical studies by industry and the 

USGS indicate that (1) two types of oil (and possibly several subtypes of each) are present, (2) Triassic and Jurassic source rocks are responsible for 

the most abundant oil type, and (3) Lower Cretaceous rocks are responsible for the other typewhich accounts for only minor amounts of North 

Slope oil. In the coastal plain of the Arctic N ationa! Wildlife Refuge (ANWR), currently being 

6 

evaluated, Triassic and Jurassic source rocks have 

probably been removed by Early Cretaceous erosion in much of the area. However, rich Lower 

and Upper Cretaceous source rocks, which are 

buried by as much as 4,000 m of Tertiary rocks 

in immediately adjacent areas, are more than adequate to generate significant amounts of oil in the 

ANWR, if the rocks are mature. 

PROSPECTING DEPOSITS FOR PEAT 

RESOURCES IN THE UNITED STATES 

Cornelia C. Cameron 

Exploration during the past two or three decades has shown the presence of large resources 

of peat in a variety of deposits occurring widely 

in the United States. United States peat resources are estimated to be 340 billion short tons 

based on an average peat deposit depth of 7 feet, 

and bulk density averaging 15 pounds per cubic 

foot for peat with a moisture content of 35 percent. In 1983 the apparent demand for agricultural 

peat in the United States was 1,144,000 tons, of 

which domestic producers provided 62 percent. 

The anticipated additional use of peat as a fuel 

source increases the forecast of total demand to 

about 1.4 million tons in 1990 and 2 million tons 

in the year 2000. Alaska contains about one-half 

the estimated resource, much of which is frozen. 

Peat deposits in conterminous United States extend southward beyond the margin of continental 

glaciation along the Atlantic, Gulf, and Pacific 

Coastal lowlands, and at high altitudes in the Appalachian and Rocky Mountains and the Sierra 

Nevada. This geographic distribution, with corresponding variation in plant types, climates, and 

physiographic and geologic settings, is reflected 

in size and shape of deposits as well as in their 

trace-element and organic-matter content, amount 

of contaminants such as clastic sediments and airfall volcanic material, and vulnerability to aerobic 

bacterial action. 

Conceptual models have proven to be useful exploration tools in the evaluation of United States 
EXPLANATION 

IT] Peat 

~ Glacio-marine clay and silt; overlain with alluvium 

along major streams 

"i :.~·~~~/. Glacial ground moraine 

Glacial end moraine 

Bedrock hills with thin blanket of grouncl moraine 

• 10 Core site and number 

N 

1 

0 

p 

FIGURE I.-Surficial geology of the Great Heath, Washington County, Maine. Inset shows location of the Great Heath, within 

the region of Maine covered by sea water during the period of maximum inundation (patterned). Lines of crors sections 

mentioned in text are shown but cross sections are omitted. Topographic contours in feet; contour interval 5 ft. 

7 
peat deposits, and their use can aid in predicting 

the possible uses of peat from a variety of geographic or geologic environments. To prepare a 

model one must select a deposit typical for a given 

geographic and geologic setting and determine as 

many of its geologic, physiographic, and chemical 

features as possible. Aerial photography and highlevel infra-red photography are useful in such 

studies. Special coring devices such as Macaulay 

and Dutch augers and Davis peat samplers are 

used to determine thicknesses and stratigraphic 

variation and to collect samples for study of the 

depositional environment, fiber size, ash content, 

Btu, and trace-element content. A geologic map 

of the Great Heath (fig. I) is part of a model for 

the domed heath type of peat deposit typical of 

the region in Maine that was covered by sea water 

during the late Pleistocene. This deposit is similar 

to a nearby deposit in the vicinity of Cherryfield, 

Maine, soon to be utilized for the manufacture of 

fuel pellets. Cross sections based on the surficial 

geology and core data show three types of organic 

material: (1) basal marsh muck resting on glaciomarine silts and clays, having a mean moisturefree ash content of 57.4 percent; (2) hemic peat 

having a mean moisture-free ash content of 4.9 

percent; and (3) fibric peat having a mean moisture-free ash content of 1.25 percent. The Great 

Heath contains estimated resources of approximately 7 million short tons of peat (dry basis). 

As a potential fuel, this peat has low-sulfur and 

high-hydrogen contents; the Btu per pound ranges 

from 8,500 to 10,000 with the hemic type having 

values above 9,500. 

ALLOCYCLIC AND AUTOCYCLIC 

CONDITIONS OF COAL FORMATION 

C. Blaine Cecil 

The spatial form and quality of coal beds are 

controlled by allocyclic and autocyclic processes 

operating during peat formation and subsequent 

diagenetic processes. Allocyclic processes are driven by energy changes external to a sedimentary 

system, such as eustatic changes in sea level, tectonic activity, and climate changes. Autocyclic 

processes are governed by the energy of the system, and include delta switching, stream meandering, and stream anastomosing. These key 

geologic processes must be qualified and quan8 

tified in a hierarchical geologic frarrework before 

lateral and vertical changes in coal beds and associated rocks can be predicted. 

The USGS develops and tests predictive models 

of coal bed quality and spatial form through both 

coal quality and basin analysis programs. My current research within the basin analysis program 

indicates that during the peat stage of coal formation, allocyclic processes are the primary controls 

on the spatial form and quality; autc~yclic processes are subordinate. 

Extensive peat deposits develop when there is 

synergism among the allocyclic prc~esses of climate, eustasy, and tectonics. Peat-forming conditions require maintenance of a water table at or 

near the peat surface, through some combination 

of an ever-wet climate, eustasy, ~ nd basin development. The extensive deposits of peat that 

are forming on the coastal areas o:f Sunda shelf 

of Malaysia and Indonesia are developing under 

these conditions. These deposits are ombrogenous, , 

they are commonly domed, and plant communities 

are zoned. They are relatively low in ash and sulfur contents. 

In areas of less rainfall, topoger0us peat deposits might form, assuming that other basinal 

conditions are met. Topogenous peat deposits 

have planar surfaces, and they are dominated by 

ground and surface water, which is relatively high 

in dissolved solids content when con~oared to ombrogenous peat deposits. Plant communities tend 

to be random, and ash and sulfur cortents are relatively high. If the water table is lowered by some 

combination of climate, sea level, or basinal conditions, then peat will not form. If th?. water table 

is elevated, by sea level rise, or subsidence, and 

(or) climate, the peat-forming envirmments may 

be replaced by marine or lacustrine environments. 

Fluvial and deltaic systems that are primarily 

controlled by autocyclic processes are not conducive to the formation of extensive peat and coal 

deposits. During periods of aggrad~.tion of such 

systems, suspended and dissolved sediment loads 

preclude the formation of extensive, high-quality 

peat. Organic deposits formed unde¥ these physiochemical conditions will generally become carbonaceous shales in the rock record. Coal deposits 

that develop in response to autocydic processes 

tend to be thin, and (or) discontiruous, and of 

poor quality. 

Predictive genetic models, therefore, must be 

developed primarily on the basis of allocyclic pro-
cesses; autocyclic processes are secondary. Depositional models are commonly unsuccessful predictors of the spatial form and quality because they 

are based on autocyclic processes of sedimentation, which predate or postdate the period of peat 

formation. Allocyclic models may be developed, 

quantified, and tested through additional integrated research focused on geochemical, mineralogical, and paleobotanical controls on peat genesis. 

STABLE ISOTOPE GEOCHEMISTRY OF CALCITE 

AND PYRITE IN THE UPPER FREEPORT 

COAL BED, WEST CENTRAL PENNSYLVANIA 

C. Blaine Cecil, Frank T. Dulong, 

Joseph F. Whelan, Ronald W. Stanton, 

and Elliot C. Spiker 

Calcite and pyrite in coal can originate from 

multiple processes. Some of these processes operate during the peat stage of coal formation and 

some operate during burial and diagenesis. Our 

study focused on determining the origins of calcite 

and pyrite in coal using stable isotope geochemistry. 

Three suites of samples were used: (1) nine samples of calcite collected from fractures (cleat) in 

the coal bed, from three different mines; (2) six 

samples from the underlying Upper Freeport 

Limestone Member of the Allegheny Formation 

and one sample from the Brush Creek Limestone 

of the Conemaugh Formation, which occurs approximately 100 feet (30 m) above the coal bed; 

and (3) samples derived from float-sink testing of 

the coal. Float-sink testing consisted of a 21-part 

size-gravity separation of each of three facies of 

the coal bed. 

All samples were ashed in a low-temperature 

plasma asher. The mineralogic composition of the 

ash was estimated using X-ray diffraction. Calcite 

and pyrite were then separated from the ash using 

appropriate heavy liquids. These minerals were 

analyzed for their C, 0, and S isotopic composition. The results indicate that at least three processes formed the calcite and two formed the pyrite. 

The composition of the cleat calcite 

(813Cx= + 13 ± 8%o; 8180=21 ± I%o) differs from 

that found in the Upper Freeport Limestone and 

the Brush Creek Limestone (813Cx=-3 ± 2%o; 

8180=25±2%o). This indicates that the cleat cal9 

cite may have resulted from fermentation and 

methanogenesis reactions; it was not derived from 

calcareous strata associated with the coal bed. 

X-ray diffraction analyses of float-sink separates 

indicated a bimodal distribution of calcite, which 

tended to be concentrated in the light and heavy 

gravity fractions. Calcite was also concentrated in 

the -100 mesh fraction. The isotopic composition 

of the calcite in the -100 mesh, and the 8x 100, 

mesh-sink 1.8, size-gravity separates was similar 

to that of the cleat calcite. 

Calcite in seven of the light gravity fractions 

had a relatively uniform 813C value of -10 ± 1%o. 

Two anomalously high 813C values ( + 12.4, + 5.4) 

were similar to the cleat calcite values. The 8180 

values range from + 9.3 to + 33.3%o. The relatively constant 813C values and the wide range in the 

oxygen isotope composition of the calcite in the 

light gravity fractions may indicate the presence 

of C02 derived from early bacterial sulfate reduction and later abiotic coalification reactions. 

Differences in 8348 values are strongly correlated with pyrite morphologies. Finely disseminated framboids and euhedral crystals are the dominant forms in the lowest facies of the coal bed; 

the 8348 values are = 1 %o. Coarser, irregularly 

shaped pyrite is the dominant form in the uppermost facies; the 8348 values are = 10%o. That both 

pyrite morphologies occur in the middle facies is 

reflected by the range in 8348 values from 0.2 to 

8. 5%o. Both types probably formed from H2S produced during bacterial sulfate reduction. The differences in the 8348 values indicate either different sulfate sources or reduction of a greater proportion of sulfate available during formation of the 

coarser pyrite. 

PYRITE OF TRANSPORTED ORIGIN IN 

REWORKED FRAGMENTS FROM THE I 

COAL BED OF THE UPPER 

CRETACEOUS FERRON SANDSTONE MEMBER 

OF THE MANCOS SHALE, CENTRAL UTAH 

E. C. T. Chao, Judith M. Back, and 

Jean A. Minkin 

Except for cross-cutting secondary veinlets, pyrite in coal is usually considered to be of primary 

origin. The occurrence of primary pyrite in coal 

is interpreted to indicate that paleo-peat swamp 

conditions were anaerobic, because the formation 
FIGURE 1.-Three types of pyrite-bearing fragments. A, vitrite fragment containing pyrite grains. Polished block (PB), diffuse 

illumination (DL). B, fragment consisting of vitrinite, semifusinite, and abundant pyrite grains. PB, DL. C, fragment 

consisting of fine-grained pyrite crystals and clay. PB, DL. D, massive pyrite replacing and encased in detrital coarsegrained clay. PB, DL. 

of pyrite requires low Eh conditions (less than 

100, as shown by Bass Becking in a 1960 study). 

We have observed pyrite enclosed in transported 

coaly and mineral-rich fragments within locally 

pyrite free coal matrices in the I coal bed of the 

Upper Cretaceous Ferron Sandstone Member of 

the Mancos Shale of central Utah. The I coal bed 

has been interpreted by us (in 1983) as allochthonous, derived primarily from plant remains that 

were transported. Thus pyrite within the fragments must have formed elsewhere, probably in 

an anaerobic environment; the fragments were 

then reworked, transported, and deposited in the 

paleo-peat swamp at the locations corresponding 

to where they were found in the resulting coal 

bed. 

Three types of pyrite-bearing fragments, each 

within a locally pyrite free matrix, have been recognized megascopically and interpreted to be of 

reworked origin in the I coal bed: (1) vitrite (fig. 

1A) and vitrite gradational with inertite (fig. 1B) 

containing pyrite grains; (2) fine-grained crystalline pyrite and clay (fig. 1C); and (3) a large fragment (2 x 3 em) of pyrite partially replacing coarse10 
grained clay, in turn completely surrounded by 

coarse-grained clay (fig. lD). We suggest that this 

latter clay -encased fragment was transported as 

a trapped fragment in a mat of floating plant debris. 

Textural characteristics suggest an allochthonous origin for the I coal bed; the presence of transported pyrite within it substantiates this interpretation. 

PETROLOGIC STUDY OF THE CHARACTERISTICS 

OF COALS OF AUTOCHTHONOUS AND 

ALLOCHTHONOUS ORIGIN 

E. C. T. Chao, Jean A. Minkin, Judith M. Back, 

and Sharon 5. Crowley 

"Autochthonous coals," as described by 

Teichmuller and Teichmuller in 1975 and 1982 

studies, "develop from plants which after death 

form peat in situ. Allochthonous coals form from 

plant remains which were transported considerable distances from their original sites" to the sites 

of deposition and peat formation. The recognition 

of an allochthonous origin for some coals has been 

somewhat controversial. Moreover, distinctions 

between the characteristics of coals of autochthonous versus allochthonous origin have not been 

clearly defined. 

On the basis of our research, the principal textural distinction between coal beds of autochthonous and allochthonous origins is that coals of autochthonous origin are finely laminated and well 

banded, whereas coals of allochthonous origin are 

coarsely fragmental and poorly banded. Allochthonous coal beds also are generally thicker, 

more variable in thickness, and more difficult to 

describe in terms of megascopic units than are autochthonous coal beds. Allochthonous coals generally have higher inertinite contents, higher mineral (ash) contents associated with inertinite-rich 

microlithotypes, and a more varied suite of minerals than do autochthonous coals. Based on our observations, as well as according to Teichmuller 

and Teichmuller's 1975 and 1982 studies, the presence of underclay may be used as evidence for 

the autochthonous origin of an overlying coal, and 

the lack of it for an allochthonous origin of a coal. 

Small amounts of coal of autochthonous origin may 

occur in a coal bed of predominantly allochthonous 

origin and vice versa. Of the coals we have 

studied, Pennsylvanian-age coals of the Eastern 

11 

United States commonly are autochthonous. Examples of allochthonous coals can be founc1 in coals 

of Mesozoic and Tertiary ages in the Western 

United States, such as the I (Utah) and Big 

George (Wyoming) coal beds. 

Autochthonous coals were derived r"imarily 

from nontransported plant remains that accumulated in quiet and stagnant (anaerob~~) peat 

swamps (conducive to pyrite formation), and probably resulted from relatively slow rates of plant 

accumulation. On the other hand, alloc]'thonous 

coals were derived primarily from plant remains 

that were transported and deposited in more energetic paleohydrologic flow regimes ard more 

aerobic peat swamp conditions (less favo~able for 

pyrite formation). Plant accumulation in the formation of allochthonous coals may occur sporadically and at a faster rate than obtains for autochthonous coals. 

GAS HYDRATES, NORTH SLOPE OF ALASKA 

T. S. Collett, K. J. Bird, L. B. Magonn, 

K. A. Kvenvolden, and G. E. Clayp~l 

Gas hydrates are crystalline compounds of 

water and gas in which the solid water lf.ttice accommodates the gas molecules in a cagelike structure, or clathrate. The formation of gas hydrates 

in well bores and pipelines has been re~ognized 

since the 1930's. Recently, naturally occmTing gas 

hydrate deposits have been detected in rrany arctic regions of the world, including western 

Siberia, the Mackenzie Delta of Canada, and the 

North Slope of Alaska. Some may have future 

economic importance. 

Direct evidence of gas hydrates on tre North 

Slope comes from a gas-hydrate-saturated core, 

and indirect evidence has been obtained f'"om drilling and open-hole geophysical logs that indicate 

the presence of a number of gas-hydrate-s~turated 

stratigraphic horizons in the Kuparuk River oil 

field. Recently completed work conducted as part 

of the U.S. Geological Survey/Departmert of Energy cooperative gas hydrate research project has 

delineated a thick zone within which gas hydrates 

would be potentially stable on the North Slope. 

Methane gas hydrate stability mapping has been 

done, using data from stabilized well-bore temperature surveys, ice-bearing permafrost de'lths and 

temperature data collected during wire-line well 

logging. This mapping indicates that gas hydrates 
may be stable to depths as great as 1,300 m in 

the Prudhoe Bay area. 

To evaluate the history of gas hydrate formation on the North Slope, the chemistry of the inplace hydrates must be examined. Geochemical 

analysis of rock samples provided by ARCO/ 

ALASKA from two wells in the Kuparuk River 

oil field reveals a complex gas chemistry within 

the shallow gas-hydrate-bearing horizons, with 

methane being the primary gas constituent. Welllog evaluation has revealed that one stratigraphically controlled gas hydrate occurrence appears to 

be reservoired with a shallow heavy oil. The physical properties of the heavy oils may be influenced 

by the presence of gas hydrates; changes in the 

reservoir characteristics, such as decreased oil 

gravities, represent an engineering problem that 

must be dealt with before production of these oils. 

A series of modifications of normal well-log 

evaluation procedures has enabled us to conduct 

several preliminary gas hydrate resource evaluations of selected gas-hydrate-bearing horizons on 

the North Slope. The identified in-place deposits 

of gas hydrates appear to be laterally continuous, 

suggesting that gas hydrates may be an unconventional source of natural gas. 

FUTURE HYDROCARBON STUDIES 

IN THE BERING SEA 

Alan K. Cooper, MichaelS. Marlow, 

and David W. Scholl 

The Bering Sea can be divided into three hydrocarbon provinces: shelf, slope, and abyssal basin. 

The shelf province, the most studied, is underlain 

by large sedimentary basins that include Bristol 

Bay and St. George and N avarin basins. Geophysical and COST well data indicate that hydrocarbon 

potential of the shelf province is variable. 

Economic hydrocarbon deposits have not been discovered to 1985 in St. George and N avarin basins. 

Potential source-rocks of Eocene age and reservoir horizons of late Oligocene and early Miocene 

age are reported for Navarin basin. In St. George 

basin, good source-rocks and reservoir rocks were 

not encountered in the COST wells but may occur 

in other parts of the basin. 

The slope and abyssal-basin provinces have received little attention from industry because of 

12 

water depths (200--3,800 m) in the region. These 

provinces may contain prospective hydrocarbon 

habitats, based on the presence of 3- to 10-kmthick sedimentary deposits, fault and fold structures, and sedimentary onlaps, featur~s similar to 

those of the shelf province. Further studies are 

planned by the USGS to look at the structure and 

evolution of these deep-water areas. 

Beginning in 1986, the GLORIA long-range 

sonar system will be deployed in the Bering Sea 

to provide a detailed mosaic of sea-floor images 

that will cover the entire slope and abyssal-basin 

region. GLORIA, gravity, magnetic-gradiometer, 

and single-channel seismic-reflection data will be 

collected along ship tracklines at 20-km spacing, 

to provide the first systematic grid of geophysical 

data recorded over the deep-water regions. These 

data will be used to refine shallow- ani deep-crustal models for the Bering Sea. 

Proposals are presently being submitted to drill 

into the abyssal-basin and slope areas of the Bering Sea using the JOIDES drill-shir RESOLUTION. Drilling will be used to estab1

ish the age 

and origin of sedimentary and igneous rocks beneath the abyssal and slope areas of the Aleutian 

Basin. The drill cores should also provide information on the paleo-environmental, depo~itional, and 

structural history of the region prior to and after 

the growth of the Aleutian Ridge and isolation of 

the Bering Sea from the Pacific Ocean. 

MEDICINE LAKE VOLCANO, CALIFOI'~IA, AND 

ITS GEOTHERMAL POTENTU' ., 

Julie M. Donnelly-Nolan 

Medicine Lake Volcano is a Pleistoce:ne and Holocene shield volcano about 50 km east-northeast 

of Mount Shasta, a location that place~· it just east 

of the main Cascade Range trend. Th ~ volume of 

Medicine Lake Volcano is estimated to be 600 

km3 , larger even than Mount Shasta, which is the 

largest of the Cascade stratovolcanoes. The presence of several late Holocene silicic flows, together with intermittent rhyolitic vol ~anism during the last 1.25 m.y., has made Meiicine Lake 

Volcano a prime target for geothermal energy exploration. Deep exploratory wells (>2 km) were 

drilled in the volcano's 7 x 12 km central caldera 

by private geothermal companies durhg 1984 and 

1985. 
Medicine Lake Volcano lies in an extensional 

back-arc setting behind the main Cascade volcanic 

arc. Major north-south-trending normal faults project under the volcano, and the dominant vent 

trend on the edifice is also north-south, indicating 

overall east-west extension. Open ground cracks 

on the surface of the volcano, some of which are 

associated with eruption of rhyolite, also suggest 

this extension direction. 

This strongly extensional environment has permitted the eruption of tholeiitic basalt similar to 

mid-ocean ridge basalt. These very low K20 magmas have erupted on the flank of the volcano 

throughout its history, as recently as late Holocene time. Derivative magmas are calc-alkaline 

and were produced by a variety of processes including crystal fractionation, assimilation, and 

mixing. Rhyolitic lavas are found on the upper 

parts of the edifice where they were typically 

erupted to the surface along dikes. One such late 

Holocene silicic eruption formed a single composite flow of rhyolite mingled with dacite, all of the 

dacite and part of the rhyolite containing chilled 

blobs of basaltic andesite. Zoned, contaminated, 

and mixed flows of various compositions are common at Medicine Lake Volcano. Typical flow volumes are Jess than 1. 0 km3 , and commonly less 

than 0.1 km3 • No large-volume ash-flow tuffs are 

present; the only large-volume (5--10 km3

) eruptions are of primitive basalt. 

Few patterns have been discerned in the chemical evolution of the volcano; in general (1) all compositions from 4 7 to 77 percent Si02 are present, 

although dacite is relatively rare; (2) the average 

composition is andesitic; and (3) individual eruptions at higher elevations on the edifice are likely 

to be small, evolved, and inhomogeneous, whereas 

the largest eruptions take place on the flanks of 

the volcano and are of homogeneous primitive 

basalt. 

Although the geologic evidence for production 

of derivative magmas suggests that shallow magmatic processes have repeatedly produced small 

rhyolitic magma bodies, geologic and geophysical 

data indicate no large silicic magma chamber 

under the volcano. Instead, primitive basalt is intruded to shallow crustal levels beneath the volcano, forming a mafic intrusive complex recognized by seismic refraction and gravity studies. 

The apparent lack of a large silicic magma 

chamber does not lessen the importance of 

Medicine Lake Volcano as a geothermal resource, 

13 

because heat continues to be supplied by intrusion 

of mafic magma into the shallow crust. 

GEOMORPHOLOGY OF THE WESTERN 

UNITED STATES EXCLUSIVE ECONOMIC 

ZONE-A GLORIA VIEW 

The EEZ-SCAN Group1 

During summer 1984 the U.S. Geological Survey conducted a reconnaissance-scale survey of 

the entire western conterminous U.S. Exclusive 

Economic Zone (EEZ) using the Institute of 

Oceanographic Sciences (UK) GLORIA long-range 

sidescan sonar system. The digital data have been 

processed and compiled into a mosaic of the entire 

survey area, which extends from Mexico to 

Canada and seaward to the 200 nautical mile 

boundary. The area covers more than 750,000 km2 

and represents a major area for future exploration. 

The sonar mosaic clearly shows the large-scale 

sediment bodies covering the sea floor (fig. 1). 

Submarine canyons incise the continental slope, 

and sediment fans that extend from them across 

the basins have an immense range of sizes and 

forms. Some channels on the sea floor are straight 

whereas others are highly sinuous, hinting that 

a variety of river-like processes occur on the sea 

floor. Vague to distinct variations in the reflectivity are probably related to differences in sediment 

composition. Any remaining notion of the deep sea 

floor as the repository of a uniform rain of sediment through the water column is soundly dispelled. 

The small basins of the continental borderland 

off southern California show as low-reflectivity depressions encircled by intricately dissected steep 

slopes with small, immature submarine fans. In 

contrast, Monterey and Delgada submarine fans 

off central California are enormous features whose 

channels, depositional lobes, and sediment waves 

extend hundreds of kilometers from their sources. 

The scattered distribution of channels and depositional lobes attests to a dynamic history of sediment transport first to one area, then seemingly 

sudden abandonment in favor of some other 

1

David A. Cacchione, David E. Drake, Brian D. Edwards, Michael E. Field, 

James V. Gardner, Monty A. Hampton, Herman A. Karl, David S. McCulloch 

(all of USGS), and Neil H. Kenyon and Douglas G. Masson (Institute of Oceanographic Sciences, Wormley, United Kingdom.) 
0 20NM 

0 40KM 

FIGURE 1.-A segment of the continental slope off the State of Washington. Shelf break is at a water depth of about 200 

m, and base of slope is at about 2,500 m. Tectonic, erosional, and sedimentary features determine slope morphology. 

course. The records show clear examples of basement ridges that block sediment dispersal, and 

sediment slides and associated mass-flow deposits 

that alter sediment-transport pathways. 

Another very striking aspect of the mosaic is 

its expression of the regional geologic diversity 

that exists along the Western United States margin. For example, the contrast between the transform and convergent tectonic regimes south and 

north of Cape Mendocino, respectively, is obvious 

at a glance. 

The continental slope in the region of convergent tectonics is crumpled into numerous folds 

that are shown as discontinuous ridges on the 

mosaics. Submarine canyons and blankets of sedi14 

ment modify the steep compressional-ridge topography, the former tending to dissect and complicate it and the latter tending to smooth and simplify it. 

Astoria and Nitinat submarine fans cover nearly 

the entire sea floor of Cascadia Basin north of 

Blanco Fracture Zone and east of Juan de Fuca 

Ridge. The fans merge along a common boundary 

and cannot be separated from one another on the 

mosaic. The distinct depositional lobes that 

characterize the large fans farther south are absent here. Close observation reveals a modern and 

relict sea-floor drainage system that includes 

lengthy channel-levee complexes extending from 

the apex of each fan, segments of abandoned chan-
nels, and scroll patterns that mark the former position of channels and document their wandering 

nature. 

The extent and continuity of features such as 

submarine fans, sea-floor channels, and debris 

flows can be easily delineated, which will lead to 

modifications of depositional models inferred from 

previous investigations. The mosaic will be an invaluable base for deciphering geologic structures 

and processes at and beneath the sea floor, for 

planning marine scientific expeditions, and for 

making optimum decisions regarding use of the 

EEZ. 

PROSPECTING FOR SHALLOW MAGMA 

CHAMBERS IN THE CASCADE RANGE 

USING SEISMIC TOMOGRAPHY 

John R. Evans, Douglas A. Stauber, 

and Phillip B. Dawson 

In the Cascade Range no seismic method has 

successfully delineated a magma chamber, though 

several methods successfully applied to other regions have been tried. Nevertheless, the area has 

high heat flow and abundant young volcanic 

rock-magma clearly is being generated and with 

a wide range of silica content. The possibility that 

Cascades magma chambers simply are smaller 

than continental silicic chambers successfully imaged with previous seismic methods prompted the 

use of the imaging method described here. This 

method is capable of resolving, in three dimensions, velocity anomalies as small as 1 km3 in the 

upper 4-6 km of the crust even when they are 

part of complex structures that make reflection 

seismology impractical. 

At Newberry volcano, Oregon, a dense two-dimensional array of 120 seismographs was deployed over the caldera and summit, and nine 

chemical explosions were detonated at distances 

of 30 to 90 km from the array. These explosions 

produced Pg and reflected P phases propagating 

upward beneath the array from many different 

azimuths. Residuals to a linear least-squares 

traveltime fit exhibited a ring of early arrivals 

coincident with the caldera ring fractures for all 

explosion azimuths, plus a small region of delays 

consistently on the far side of the caldera from 

each explosion. 

15 

A 

B 

EXPLANATION 

n Mavma f D~~~~ ~ sills 

c:J 

Volcani-: flows 

a-td 

sedlmentuy units 

Pre- Tertiary 

Crystalline 

Bas~ment 

No vertical excrvveration 

5 KM 

INDEX MAP SHOWING LOCATION OF NEWBERRY VOLCANO 

FIGURE I.-Models of Newberry volcano, Oregon. A, tomographic velocity perturbation contours in percent of mean 

velocity (positive fast); B, interpretive model. 

Both a simple geometric interpretation and a 

damped-least-squares inversion of these Pg and 

reflected-phase residuals reveal a ring of high-velocity material around the ring fractures and extending from near the surface to a depth of 3 or 

4 km (fig. 1A). About 3 km depth under the center 

of the caldera is a small (approximately 1 km3

) 

low-velocity anomaly that causes the azin-uth-dependent delay. This velocity structure is interpreted, in part, as a ring of crystalline intrusiYe rocks 

emplaced along the caldera ring-fracture system 

(fig. 1B). The deeper, low-velocity feature may be 

a small (probably silicic) magma chamber, or may 

be porous flows, breccias, and sedimentf downfaulted by the ring fractures. 

Both features may make good geothermal 

targets. The ring intrusions may include hot recently solidified rocks and the ring fractures may 

serve to channel water. The low-velocity rnaterial 
may be the main shallow heat source, or a porous 

medium and good aquifer in an area known to 

exhibit high well-bottom temperatures. 

A similar experiment is in preparation for 

Medicine Lake volcano, northern California. A 

dense array of 140 seismographs will be deployed 

across the caldera, summit, and youngest silicic 

flows to receive Pg from eight azimuths. Preliminary results from this experiment should be available in early 1986. 

GEOTHERMAL SIGNIFICANCE OF AN 

EXTENSIVE CONDUCTOR BENEATH 

NEWBERRY VOLCANO, OREGON 

D. V. Fitterman, R. J. Bisdorf, W. D. Stanley, 

and A. A. R. Zohdy 

Newberry Volcano is a large Quaternary volcano located in central Oregon, ranging from 

basaltic to rhyolitic composition. It is composed 

of flows, ash-flow and air-fall tuffs, domes, and 

alluvium. Several hundred cinder cones and fissure vents dot its flanks. Extensive evidence of 

young, rhyolitic volcanism suggests that a geothermal reservoir might be associated with the 

volcano; high observed temperatures in the USGS 

Newberry 2 test hole (265°C at 930 m) in the caldera support this idea. Extensive geophysical work 

has been carried out on and around Newberry 

Volcano in an attempt to characterize a potential 

geothermal reservoir. The electrical techniques 

used include transient electromagnetic, Schlumberger, and magnetotelluric (MT) soundings; all 

these methods present a consistent picture. The 

data indicate two regions, divided approximately 

by the caldera boundary. Inside the caldera the 

geoelectrical section is characterized by moderate 

resistivities (50-200 ohm-m) to a depth of about 

400 m, corresponding to lacustrine deposits and 

fragmental volcanic rocks, as determined by drilling. Beneath this layer, the resistivity decreases 

significantly to values of from 2 ohm-m to 50 ohmm. Comparison of the temperature logs from the 

Newberry 2 well with the interpreted electrical 

section shows that this decrease in resistivity occurs at about the same depth as a high-temperature convective region. High-permeability lava 

flows and breccia allow fluid convection and lower 

resistivities. 

Outside the caldera a very resistive surface 

layer (500-10,000 ohm-m) is underlain by a con16 

ductor (10-100 ohm-m) starting at depths from 300 

m to 800 m. Below the conductor at depths from 

1.5 km to 4.1 km, the MT soundings indicate the 

presence of resistive (>200 ohm-r) electrical 

basement, which is interpreted to be pre-Tertiary 

intrusive rocks. With the exception of a region adjacent to the west edge of the calderR, the conductor deepens away from the caldera; just west of 

the caldera, the conductor varies in depth from 

300 m to 400 m. MT surveys have identified the 

conductor as a regional feature wl'ich extends 

over much of the High Cascades and eastern Oregon. Because any geothermal develop'llent will be 

restricted to regions outside the caldera, it is important to know if this conductor hdicates the 

presence of hot fluids as observed in the caldera. 

There are several possible explanations of the 

extra-caldera conductor. Increased water saturation with depth is an unlikely explanation, because 

fresh, meteoric water is resistive, an-1. at greater 

distances from the volcano, the top of the conductor occurs below the regional water table. On the 

flanks of the volcano, alteration of the pre-Newberry and Newberry rocks is the most likely 

mechanism to explain the conductor. 

We believe that the conductor inside the caldera 

suggests the presence of a potential geothermal 

reservoir. The shallow conductive retrm just west 

of the caldera may have been produc~~d by extensive alteration assocated with a hydrothermal system and thus represents a good geothermal 

target. Elsewhere on the flanks of the volcano, 

alteration by heat from the numerous cones and 

vents causes the conductor, which is not considered to be a geothermal target. Further from 

the volcano, the conductor is thought to be 

slightly altered Tertiary volcanics and TertiaryMesozoic sedimentary rocks. 

ORGANIC CARBON ACCUMULATrON AND 

SULFUR DIAGENESIS IN FINE-GRAINED 

CRETACEOUS ROCKS OF Tr ~~ 

WESTERN INTERIOR OF NORTH I' 'llERICA 

Donald L. Gautier and Lisa M. Pratt 

Fine-grained, organic carbon-rich Cretaceous 

rocks are an important source for petroleum in 

the Western Interior. These carbon-r~~h rocks can 

be classified as occurring in calcareous and noncalcareous systems. To gain a better understanding 

of organic matter accumulation and preservation, 
we have examined the sedimentology and 

geochemistry of organic matter and sulfur-bearing 

constituents of these two systems. 

The content of organic carbon is inversely proportional to sedimentation rate in most fine-grained 

Cretaceous rocks of the Western Interior, and 

rates of organic-carbon accumulation were similar 

in organic carbon-rich rocks of both calcareous and 

noncalcareous systems. Rocks containing more 

than 4 weight percent organic carbon were deposited at rates of less than 10 m/m.y.; at higher 

sedimentation rates dilution by calcareous or noncalcareous constituents resulted in lower organic 

carbon content but not in lower organic carbon 

accumulation rates. The type of organic matter 

preserved is controlled by the intensity of aerobic 

diagenesis and by the influx of terrestrial organic 

matter. 

Processes of sulfur diagenesis are sensitive to 

the degree of bottom-water oxygenation and 

bioturbation, and to how much organic matter is 

present and how readily it metabolizes. Consequently, isotopic ratios of pyrite sulfur and sulfur: carbon ratios are particularly useful in interpreting conditions of deposition and early 

diagenesis in the Cretaceous rocks of the Western 

Interior. 

Among noncalcareous rocks, 834S of pyrite sulfur varies systematically with oxygenation in the 

depositional environment. Laminated shales with 

more than 4 percent organic carbon contain disseminated pyrite that is strongly depleted in 34S 

(834S=-31 %o) and their organic matter is hydrogen rich. In contrast, samples with less than 1.5 

percent organic carbon are intensely bioturbated, 

have pyrite that is much less depleted in 34S 

(834S=-12.4 %o); their organic matter is hydrogen 

poor. 

Pyrite in limestone concretions displays systematic sulfur isotopic values ranging from -18 %o 

on the margins to + 16 %o in the center. Such a 

wide range, in contrast to the uniform values of 

surrounding shales ( < 24 %o), illustrates the extent to which concretion formation occurs as a 

closed system, and suggests that sulfur isotopic 

information from concretions should not be directly used in interpreting depositional and early 

diagenetic conditions. 

Sulfur:carbon ratios in noncalcareous rocks are 

much higher than in organic-rich rocks of the calcareous system. This relationship suggests that 

either (1) the organic carbon-rich shales in the calcareous system accumulated beneath anoxic but 

not sulfidic bottom waters, whereas the noncalcareous, organic carbon-rich shales accumulated 

beneath bottom waters that were both anoxic and 

sulfidic, or (2) that the carbonate system was iron 

limited. Sulfur diagenesis is thus directly related 

to quality of hydrocarbon source rocks. Investigations of the sulfur system lead to better understanding of the conditions of oil and gas generation. 

GENESIS AND IDENTIFICATION OF THE 

COLORADO PLATEAU URANIUM PROVINCE 

Harry C. Granger, Warren I. Finch, 

Fred Peterson, Morris W. Green, 

Richard F. Sanford, C. S. Bromfield, 

and F. Allan Hills 

The Colorado Plateau Uranium Province 

(CPUP) occupies a large part of the Colorado 

Plateaus physiographic province, from which it 

derived its name. It corresponds broadly to the 

area of major uranium deposits within Pennsylvanian through Jurassic sedimentary rocks in the 

province. In contrast, the edges of the CPUP as 

well as adjacent areas are either devoid of deposits or contain only minor deposits in either Tertiary volcanic and sedimentary rocks or Precambrian basement rocks. 

Orthogonal sets of lineaments trending northeast and northwest across the region reflect structures that were periodically active in late Paleozoic through Mesozoic time and which exerted significant control on the positions of contemporaneous intracratonic basins and related sedimentary 

facies. Fluvial sandstone facies, in particular, contain most of the uranium deposits, and finegrained volcaniclastic rocks overlying the sandstones are presumed to be the source of much of 

the uranium. Both structural features and sedimentary facies controlled the flow of ore-forming 

ground water. 

Isotopic age determinations suggest that the 

major deposit types, distinguished by host formation, form, and mineral assemblage, resulted from 

three separate mineralizing episodes. The first 

was a major, widespread episode at about the end 

of Triassic time that resulted in deposits of the 

Coconino/Supai, Cutler, and Chinle types; the second was a minor localized episode in Middle Juras17 
Aerial view, west side of Mount Rainier, Washington State. Photograph by Lyn Topinka, David A. Johnston Cascades Volcano 

Observatory, Vancouver, Wash. , September 1977. 

sic time that created deposits of the Todilto and, 

perhaps, Entrada types; and the third and dominant episode occurred at about the beginning of 

Cretaceous time and created the Westwater Canyon and Salt Wash types. Each of the two major 

episodes followed the only two massive accumulations of volcaniclastic strata in the region. This 

volcanic debris was derived from volcanic arcs far 

to the south and west and, as already noted, is 

believed to be the source of much of the uranium 

in the deposits. 

Most geologic characteristics of the CPUP are 

not unique to the Colorado Plateaus province, but 

together they caused episodic uranium mineralization. The essential characteristics were (1) existence of a relatively stable continental foreland, 

(2) accumulation of continental host rocks, (3) a 

contemporaneous volcanic (or granitic) uranium 

18 

source, (4) uraniferous shallow meteoric ground 

water derived from the volcanic or granitic detritus, (5) localization of uranium by adsorption 

and (or) reduction from uraniferous ground 

water either (a) percolating through a reducing 

environment imposed by degrading organic matter 

and hydrogen sulfide, or (b) encountering upwelling, deeply circulated, saline grbund water at an 

interface within reduced host rocks, and (6) preservation promoted by crustal stability and longterm burial. 

Details of the mineralizing processes are still 

not known and remain controversial. The uranium 

deposits of Mesozoic age in the Colorado Plateaus 

province, however, seem to have morphologic, 

mineralogic, and genetic characteristics that distinguish them from other known deposits, 

worldwide. 
GEOLOGY AND GEOCHEMISTRY OF THE 

PRECAMBRIAN ROCKS OF THE 

READING PRONG, NEW YORK AND 

NEW JERSEY-IMPLICATIONS 

FOR THE GENESIS OF 

IRON-URANIUM-RARE EARTH DEPOSITS 

Linda C. Gundersen 

The Hudson Highlands and New Jersey Highlands, which make up the northern part of the 

Reading Prong, are complexly deformed, Grenville-age metamorphic rocks, typical of the upper 

amphibolite-lower granulite facies of regional 

metamorphism. Four major stratigraphic units 

have been recognized in these rocks: (A) a calcsilicate gneiss, consisting of a basal hornblende 

amphibolite and pyroxene gneiss with minor 

quartz-feldspar gneiss, marble, and allanite and 

scapolite-bearing gneisses; (B) a quartz-oligoclase 

gneiss with minor hornblende and pyroxene amphibolite; (C) a hornblende gneiss; and (D) a 

metasedimentary sequence consisting of graphitic 

quartz-feldspar gneiss, graphitic biotite gneiss, biotite-garnet gneiss, and minor hornblende-feldspar gneiss, marble, and pyroxene gneiss. Magnetite deposits, from which iron was produced in the 

18th and 19th centuries, occur as concordant 

layers within the calc-silicate and hornblende 

gneiss throughout the Reading Prong. Individual 

magnetite trends are traceable along strike for 1-

15 km and are in places associated with high concentrations of uranium and rare-earth elements. 

Detailed geologic mapping, petrography, and 

major and trace-element analyses of both outcrop 

samples and samples selected from over 9,000 feet 

of drill core from the Greenwood Lake quadrangle, along with chemical analyses compiled 

from the literature, have led to the following observations and conclusions: 

1. Rocks identified as volcanic, based on stratigraphic position and whole-rock chemistry (the 

quartz-oligoclase gneiss, pyroxene gneiss, and 

hornblende and amphibolite gneiss), were plotted 

using the methods of Irvine and Baragar's 1971 

study. They define a calc-alkaline trend with a 

minor tholeiitic component, suggesting that they 

originated in a mature marginal marine basin. All 

other rock types were plotted in the same manner 

and display no apparent trends. 

2. Magnetite occurs as elongate bodies in the 

cores of folds or as thick sequences of alternating 

bands with quartz and pyroxene, suggesting it 

was originally banded iron-formation. Iron and 

copper sulfides are present in variable amounts. 

3. Ore-grade concentrations of uraninite are 

stratabound within magnetite layers in a number 

of the deposits. U raninite crystals that vary in 

size from several micrometers to several millimeters across occur as inclusions and alo'1g grain 

boundaries of diopside, magnetite, allanite, and 

sphene. Conversely, magnetite and sph~ne can 

also be found within uraninite. 

4. High concentrations of rare-earth elements 

resulting from the presence of layers of :xenotime 

and monazite are found in the metasedi:'llentary 

rocks. Pyroxene gneiss and hornblende gneiss 

close to the magnetite mines contain anor1.alously 

large amounts of light rare-earth elemerts commonly occurring in allanite. Magnetite ore also 

contains large amounts of light rare-earth elements occurring in apatite and allanite. 

The rock sequence and mineral deposits just described may have originally been deposit.ed in a 

marginal marine basin as (A) basic to internediate 

volcanics, volcaniclastic and carbonate seciments, 

and exhalative iron, sulfide, and uranium-rich 

horizons; (B) acidic volcanics; (C) basic Yolcanics 

and exhalative iron, sulfide, and uranium-rich 

horizons; (D) acidic volcaniclastics, carbonaceous 

pelitic sediments with rare-earth elem ~nt-rich 

horizons, and carbonates. Rare-earth element enrichment of rocks close to the magnetite deposits 

may have resulted from the circulation of C02-rich 

fluids during Grenville-age metamorphism. 

MARINE CEMENTATION AND EARLY 

POROSITY LOSS IN BANK-MARGI~~ 

CARBONATES-EXAMPLES FROM ENEWETAK 

Robert B. Halley, Eugene A. Shinn, and Larry 

A. Beyer 

Marine cements commonly occlude por~ space 

in carbonate rocks of reef and other bank-margin 

facies. Study of Miocene and younger car"lonates 

on Enewetak Atoll during 1984-85 reinfor~es observations from more ancient rocks that marine 

cementation is more active on margins of carbonate banks than within bank interiors. 

19 

Surficial intergranular marine cementation occurs on the rim of Enewetak Atoll, as evidenced 
by lithified reef rubble that extends up to 2 km 

lagoonward and forms a back-reef, cemented surface up to a few meters thick. Marine-cemented, 

low-porosity rock is exposed by a submarine 

rockfall on the northern edge of the atoll that left 

a scarp extending several hundred meters deep 

in the bank margin. Massive marine cementation 

extends down the seaward slope of the atoll to 

depths greater than 350 m. In addition to intergranular cementation, marine cement as thick as 

several centimeters coats voids and fractures in 

bank-margin sediments. Massive marine cementation is evident into the margin as far as the scarp 

extends but was not found in a drill hole about 

1 km lagoonward of the bank margin. 

Core drilling during 1985 in the lagoon confirmed earlier observations that marine cements 

are scarce and account for little porosity loss in 

the bank interior. High porosity, typical of modern, unconsolidated, carbonate sediments, characterizes the lagoon cores; porosity is high for one 

of two reasons: (1) sediments have remained 

largely unaltered, retaining metastable mineralogy and original porosity; or (2) sediments have 

altered in fresh water, during which porosity loss 

due to calcite cementation is largely compensated 

by secondary porosity development through 

aragonite dissolution. The latter events occur during sea-level low stands (glacial periods) when the 

marine sediments of the atoll are exposed to 

meteoric-water diagenesis. The high porosity of 

lagoon cores is evident in thin sections, hand samples and density logs, and occurs in marked contrast to the low-porosity, marine-cemented limestones of the bank margin. 

Carbonate platform margins have generally 

been favorable sites for oil and gas exploration; 

numerous hydrocarbon reservoirs have been found 

in these facies during the last 50 years. Within 

platform margins, marine cementation has adversely affected the reservoir quality of carbonate 

hydrocarbon reservoirs of many periods and is 

particularly important for reservoirs of Devonian, 

Permian, and Cretaceous age in North America. 

The marine cementation pattern from Enewetak 

and other modern and ancient carbonate platforms 

suggests the outermost platform edge may be unfavorable for the development of reservoir rocks 

due to marine cementation and early porosity loss. 

TAPHONOMY OF NONMARINE 11•0LLUSKS 

AS AN INDICATOR OF 

ALLUVIAL-LACUSTRINE SEDIMENTATION 

John H. Hanley and Romeo M. Flores 

Depositional processes and paleoo.nvironments 

are readily interpreted from the taphonomy of 

freshwater mollusk assemblages i11 the Tongue 

River Member of the Fort Union Formation (Paleocene), in the northern Powder River Basin, 

Wyoming and Montana. The composition, species 

abundances, and spatial and temporal distribution 

of these assemblages were controllei not only by 

the environments in which the mollu~l<s lived, but 

also by the depositional processes that affected 

the mollusks after death and before final burial 

(for example, transport, reworking and concentration of shells, and mixing of faunal elements from 

discrete habitats). These post-mortem processes 

produced a taphonomic "overprint" en assemblage 

characteristics that directly reflects alluvial-lacustrine sedimentation. The "overprint" can be interpreted through outcrop analysis of the biofabric, 

that is, the orientation, fragmentation, size sorting, abrasion, density, and dispersior of shells; the 

nature and extent of shell infilling; and the ratio 

of articulated to disarticulated bivalves. 

Studies of mollusk taphonomy draw upon and 

augment sedimentologic studies. For example, 

post-mortem depositional processes that affected 

mollusk assemblages are revealed by sedimentologic characteristics such as litholory, stratification sequences, and bed configurations. 

Taphonomic interpretations are based in part 

upon these characteristics, but emphasize the 

sedimentology of mollusk shells through interpretation of the biofabric of assemblages. 

In the study of the alluvial-lacustrine Tongue 

River Member, we used taphonomy in conjunction 

with other paleoecological criteria (composition, 

species abundances, and distribrtion of assemblages) to differentiate in-plac?., reworked, 

transported, and ecologically mixec1 mollusk assemblages. Our research defines paleontologic 

criteria for recognition of the varied environments 

in which these assemblages were de"'losited: large 

flood-basin lakes (on and off shore), small floodbasin lakes, crevasse-splay feeder ell annels, distal 

crevasse splays, and lake-crevasse d~ltas. Theresults of our studies indicate that taphonomy of 

20 
mollusk assemblages-a heretofore underappreciated tool for paleoenvironmental interpretation-augments sedimentology for differentiating 

alluvial-lacustrine environments. Integration of 

paleoecology and sedimentology provides interdisciplinary criteria for interpretation of the paleoenvironmental framework of coal-forming environments, paleogeographic relations, and modeling 

the evolution of Tongue River Member deposition. 

CONODONT THERMAL MATURATION PAnERNS 

IN PALEOZOIC AND TRIASSIC ROCKS, 

NORTHERN ALASKA-GEOLOGIC AND 

EXPLORATION IMPLICATIONS 

Anita G. Harris, I. L. Tailleur, and 

H. Richard Lane2 

The Paleozoic through Jurassic stratigraphic sequence in the Brooks Range, northern Alaska, 

consists chiefly of platformal to intraplatform 

basin deposits 1-5 km thick. This comparatively 

thin sequence of heterogeneous lithologies was 

tectonically disrupted and shortened at least 600 

km to form a stack of allochthons that were transported relatively northward and emplaced during 

earliest Cretaceous time. The Seward Peninsula 

appears to be a southwestern continuation of 

Brooks Range geology. Most of the western % of 

the Seward Peninsula contains 4-5 km of unmetamorphosed platformal, dominantly shallow 

water carbonate rocks of Early Ordovician 

through Devonian age. Eastward, these rocks are 

thrust onto a blueschist terrane of mafic volcanogenic and clastic deposits and mixed carbonate and clastic rocks of probable Ordovician 

through Silurian age. Adjacent to and possibly infolded with these rocks are metamorphosed shallow-water carbonates of Cambrian through Devonian age similar to the rocks of the western 

Seward Peninsula. 

Cambrian through Triassic rocks make up at 

least 40 percent of the surface bedrock in northern 

Alaska, chiefly in the Brooks Range and Seward 

Peninsula. Thermal patterns in these rocks are 

based on conodont color alteration indices (CAl) 

from 2,000 collections representing 450 localities. 

2

H. Richard Lane, AMOCO Production Company Research Center, P.O. Box 

591, Tulsa, OK 74102. 

These patterns show: (1) a gradual increase in 

thermal level from the northern margin of the 

Brooks Range to about 3

/4 of the distance across 

the range (from CAl 1 to 5.5 and above); (2) a 

belt of mixed high values (CAl 4. 5 to 7) along 

the south border of the range; (3) thermal levels 

in surface and subsurface samples that are related 

to tectonic burial and not prethrust burial 

metamorphism, because CAl values in coeval 

rocks increase downward through the stack of allochthons; (4) the same CAl values in rocks above 

and below the Ellesmerian unconformity in the 

northeast Brooks Range; (5) an association of 

anomalously high CAl values with mineralized 

areas and plutonic rocks; and (6) a few anomalously high CAl areas of unknown origin that deserve geologic attention. 

CAl mapping of northern Alaska shows that 

Cambrian through Devonian rocks in the geologically complex area of the western Seward Peninsula, along the northernmost edge of the western 

and central Brooks Range, and a very small area 

around the Yukon River at the Canadian border 

have thermal potential for hydrocarbons. In 

nearly all these areas, however, most of these 

rocks are beyond the thermal limit for oil. Areas 

that have thermal potential for both oil and gas 

in Mississippian through Triassic rocks include the 

subsurface of the north flank of the Colville basin, 

a 50-km-wide belt along the north flank of the 

Brooks Range as far east as the Philip Smith 

Mountains, and a small area around the Yukon 

River at the Canadian border. 

THERMAL MATURITY MODELING AND 

GEOCHEMICAL CHARACTERIZATION OF 

HYDROCARBON SOURCE ROCKS, OILS, 

AND NATURAL GASES OF 

THE ANADARKO BASIN 

J. R. Hatch, D. D. Rice, R. C. Burruss, 

J. W. Schmoker, and J. L. Clayton 

We report initial results of a study of the timetemperature history, hydrocarbon-source-rock 

characteristics, and geochemistry of oils and natural gases of the Anadarko basin. Despite the complex structural history of the basin, published 

measurements of vitrinite reflectance (R0 in percent) in the central basin indicate a reasonable 

21 
Paleoecology of freshwater mollusks augments sedimentology for interpretation of alluvial-lacustrine environments. For example, high sedimentation rates associated with crevasse splays may be reflected 

by bivalve escape structures. Photograph illustrates unsuccessful attempt of a freshwater bivalve 

(Plesielliptio sp.) to reach sediment-water interface by burrowing upward following rapid aggradation 

of sand during crevassing. Tongue River Member of Fort Union Formation (Paleocene), Powder 

River Basin, Montana. Photograph by J. H. Hanley, 1975. 

22 
correlation between thermal maturity and present 

burial depth, z (feet): R0 =0.32ez19580. When related to vitrinite reflectance, Lopatin's time-temperature calculations (TTl) provide a useful predictive model for thermal maturity patterns 

throughout the basin both now and in the geologic 

past. The empirically calibrated equation specific 

to the Anadarko basin is: R0 =0.30(TTI)0·

21. For 

a given TTl, this equation results in a lower Ro 

than predicted using Waples' 1980 calibration, 

which was based on the average of many basins. 

Results of organic carbon and Rock-Eval 

analyses of potential hydrocarbon source rocks reveal large variation in richness and preserved organic matter type. The Middle Ordovician 

Simpson Group and Upper Ordovician Sylvan 

Shale are in general organic lean ( < 1 percent total 

organic carbon, TOC) and have limited or poor hydrocarbon-source-rock potential. The Upper Devonian-Lower Mississippian Woodford Shale is organic rich (1-14 percent TOC) with two distinct 

organic matter facies. Woodford Shale in the 

southern, southeastern, and eastern parts of the 

Anadarko basin contains type II (oil prone) organic matter compared to type III (gas prone) organic matter in the northern and western areas. 

Pennsylvanian shales with 1-5 percent TOC contain type III organic matter, whereas most Middle 

and Upper Pennsylvanian shale intervals (such as 

Stark Shale) with higher amounts of organic matter (6-18 percent TOC) contain type II organic 

matter. 

With increasing depth (11,860-21,610 ft) in the 

central basin, thermogenic natural gases in Pennsylvanian sandstone reservoirs are isotopically 

heavier and chemically drier (813C1 (methane): 

-49.2 to -33.2 %o, 813C2 (ethane): -38.3 to -30.7 

%o, 8D1 (methane): -162 to -131 %o, and C1/C1-4: 

0. 74 to 0.99). Deviations from this trend are believed due to mixing of gases generated from different source rocks at different levels of thermal 

maturity. In contrast, thermogenic gases produced from 1, 735 to 6,685 ft in the giant Hugoton 

field on the northwest flank of the basin show little isotopic and chemical variation (813C1: -44 to 

-42%o, 813C2: -34.3 to -32.2 %o, 8D1: -169 to -

154%o, C1/C1- 4 : 0.69 to 0.84). These gases are believed to have been generated at lower levels of 

thermal maturity than those in the central basin. 

Chromatographic analysis of 24 whole oils from 

depths of 5,145-16,360 ft in the central basin reveals three general oil types. Type 1 occurs in Or23 

dovician reservoirs, has pronounced odd carbon 

preference in the C11-C19 n-alkanes, and very low 

abundance of isoprenoids. Type 2 is found in Devonian and Mississippian reservoirs, shows no odd 

carbon preference, and has n-alkanes as the most 

abundant components in the gasoline range (C4-

C7). Type 3 occurs in Pennsylvanian re~ervoirs 

and is generally similar to type 2, but d:ffers in 

having methyl cyclohexane (MCH) always greater 

than heptane (n-C7), with MCH/n-C7 up to =2. 

Intermediate oil compositions are consistent with 

mixing of oil types, especially between typ?.s 1 and 

2, and types 2 and 3. Some multi-reservoir fields, 

however, show stratigraphically distinct ('~1 types 

demonstrating lack of fluid communicatior during 

oil migration. In the northernmost shelf areas of 

western Kansas and southwestern N ~braska, 

geochemically similar, type 2 oils occur in Cambrian and Ordovician through Upper Penns~rlvanian 

reservoirs. These oils correlate with extracts of 

the Woodford Shale from depths greater than 

6,000 ft in the central Anadarko basin, implying 

oil migration of as much as 350-400 miles. 

A NEW APPROACH TO ORGANIC 

GEOCHEMICAL STUDIES OF THE COALIFif::ATION 

PROCESS-CHEMICAL AND PHYSIC,l\L 

EVOLUTION OF COALIFIED LOGS Af A 

FUNCTION OF RANK 

Patrick G. Hatcher 

Traditional studies of coalification have focused 

on the chemical evolution of coal without <''>nsidering its heterogeneous chemical composition. My 

study devoted specific attention to on€ of the 

major components of coal, that derived from 

woody tissue. It is only by study of individual, 

genetically related components in coal of various 

ranks that we can gain a better understanding of 

the process which transforms cellular, woody 

plants buried in peat to structureless vitrinite in 

coal. Woody tissue and coalified woody tissue collected from a variety of depositional associations 

including peat, coal, sandstones, and shales have 

been studied with diverse organic geochemical and 

microscopic methods to ascertain the changes in 

chemical and physical composition broug]'t on by 

the coalification process. The methods used include pyrolysis/gas chromatography/mar" spectrometry and solid-state 13C nuclear mag"letic re-
sonance spectroscopy (NMR). The NMR studies 

include use of the new dipolar dephasing method, 

which enhances signals for nonprotonated carbons 

and allows more detailed organic chemical structural analysis than is available from the conventional solid-state 13C NMR method. 

These sophisticated analytical tools for organic 

structural analysis have provided some new insights into the overall process of coalification. 

Woody tissue, when buried in peat, is transformed 

microbiologically by degradation and removal of 

labile organic substances such as carbohydrates, 

with selective preservation of lignin-like substances. This early diagenetic transformation can 

occur with little or no loss of cellular morphology. 

In contrast to traditional views, the lignin-like 

substances survive early diagenesis in a relatively 

unaltered state without transformation to soluble 

humic acids. 

As coalification progresses to a rank equivalent 

to lignite, the lignin-like material is significantly 

altered chemically, but the woody tissue retains 

its cellular morphology. That cellular morphology 

is retained is evidence that the alteration does not 

involve a soluble humic acid intermediate (which 

some believe condenses to an insoluble gel). 

Rather, the lignin macromolecules are chemically 

altered directly as solids, and any soluble humic 

acid-like material appears to be a by-product of 

this alteration. These oxygen-rich humic substances can be mobilized from the coal during compaction and dewatering. In the process, the residual insoluble material may become depleted of 

oxygen, which would explain the observed loss of 

oxygen from coal as rank increases from lignite 

to bituminous coal. The dipolar dephasing NMR 

data show that loss of oxygen is coupled to an 

increase in the number of protonated carbons, also 

consistent with the above hypothesis. 

Physical changes in coalified woody tissue occur 

independently of the organic chemical changes, 

except in samples having a finite amount of cellulose still present. This suggests that a certain 

degree of chemical uniformity must exist before 

cellular morphology degrades and the remnant cell 

walls coalesce to form structureless vitrinite. Once 

chemical homogeneity is achieved, coalescence becomes more a function of compactional pressure 

than of chemical changes. 

As coalified woody tissue undergoes further 

transformation at ranks greater than that of 

bituminous coal, its organic chemical composition 

is radically altered, primarily by loss of aliphatic 

24 

structures. The dipolar dephasing data suggest 

that condensation of aromatic rings occurs at this 

stage, consistent with the traditiond views about 

coalification at high rank. 

SULFUR HEXAFLUORIDE GA.$ AS A 

STABLE TRACER OF GEOLOGICAL AND 

GEOCHEMICAL PROCESSES-APPI.CATION TO 

THE ENERGY INDUSTRY AND EARfH SCIENCES 

J. R. Herring and G. M. Re:~mer 

The use of sulfur hexafluoride (SF 6) as a stable, 

gaseous tracer is common in the at~ospheric sciences, but it is applicable to the ear+.h science and 

energy industries as well. The SF 6 technique is 

rapid, inexpensive, and extremely accurate and 

precise at very low concentration levels in air. 

Few other tracer techniques offer its many advantages: ease of detection, self-contained, suitcasesize, field-portable instrumentaticn for about 

$5,000 (1985), and data acquisition 2nd analysis in 

real time on site. Of consequence to releases of 

the tracer into the environment and stability of 

the tracer, the gas is both chemically stable and 

nontoxic. The natural background of SF 6 in air 

is low, about 1 part per trillion, wlJ ich eliminates 

annoying or interfering background signals. Most 

important, the detection limit of the instrument 

is a sensitive few parts per trillion (for example, 

a standard cylinder of gas, about 6 m3 at STP, 

diluted into a cube of air 18 km on edge). This 

allows extremely detailed tracer studies to be performed. 

As an example of geologic appli ~ation of this 

technique, we have used the tracer to define the 

structure and extent of an abandoned, underground, burning coal mine. This particular study 

is directly relevant to studies in gH1logic hazards 

and mining, as well as relevant to geologic engineering. The interest in determining the extent 

of this mine lies in providing new information on 

the combined hazards from fire and possible subsidence at the abandoned workings. We have enhanced the tracer technique by conbining sulfur 

hexafluoride with helium, taking adnantage of the 

differences in diffusion properties between the 

two gases. Specifically, our study SO'lght to define 

(1) the extent of the abandoned mine workings, 

(2) diffusion rates of helium and sulfur hexafluoride through the partially collap"ed mine, and 
Mount Shasta, California, from the north. Photograph by Lyn Topinka, David A. Johnston Cascades Volcano Observatory, 

Vancouver, Wash., July 1984. 

(3) extent of intercommunication throughout the 

mine, to assess the possible spread of the fire. 

Our results show that we have been able to define the extent of mine workings, to obtain some 

idea of where the workings are flooded, and to 

model the diffusion of the two gases through the 

mine workings. As expected, eddy diffusion greatly dominates molecular diffusion in the dispersion 

of gases throughout the workings. Finally, we 

have determined that much of the mine remains 

connected, not only throughout its own extent but 

also to other, adjacent mines. Therefore, should 

the mine fire continue to burn, it is capable of 

spreading throughout much of the rest of the mine 

not on fire and to other neighboring mines as well. 

The mine study is simply one example of the 

use of this tracer technique. Other potential 

geologic applications include tracing underground 

structure, determining extent of communication 

between underground locations, and measuring 

25 

rock permeability and porosity as well as largecavity volume. In addition, fracture zones and 

zones of increased permeability can be delineated 

with the gas. 

GROUND-WATER COMPOSITION AS AN 

INDICATOR OF SODIUM CONTENT IN 

COAL IN THE POWDER RIVER BASIN, 

SOUTHEASTERN MONTANA AND 

NORTHEASTERN WYOMING 

Ricky T. Hildebrand 

Deposits of subbituminous coal in the Tongue 

River Member of the Fort Union Formation (Paleocene) often attain thicknesses of more than 30 

m (100 ft) and lie within 150 m (500 ft) of the 

surface. This coal usually has low ash and sulfur 

contents, but often contains high concentrations 
Anticline-syncline pair in Ordovician Viola Limestone, showing compressive deformation in area of Southwest Davis oil field 

along southeastern margin of Anadarko basin. Original color slide by W. J. Perry, April1985. 

of sodium. High sodium is an undesirable impurity 

that contributes to ash fouling in coal-fired boilers, 

and much research has been devoted to methods 

of mechanically or chemically reducing the sodium 

content of low-rank coal. 

The coal deposits of the Tongue River Member 

are major aquifers in the Powder River Basin. 

The coal saturated by ground water is a dynamic 

hydrogeochemical system in which the concentrations of major cations and anion complexes tend 

toward chemical equilibrium. Adsorbed sodium, 

for example, enters into the following cation-exchange equilibrium reaction with calcium ions in 

solution under standard chemical conditions (STP): 

2N a+ (ad)+ Ca2 + ~Ca2 +(ad)+ 2N a+. The direction in which this reaction will proceed depends 

on the relative concentrations of the ions and the 

adsorption affinity of the substrate. 

To investigate the chemical processes controlling the sodium content of coal, I compared concentrations of calcium, magnesium, and sodium in 

coal and ground-water samples from stratigraphically equivalent coal deposits. The results suggest 

that the sodium content in coal depends on the 

relative concentrations of the divalent calcium and 

magnesium cations and of monovalent sodium cations in solution. These cation concentrations, 

which define the sodium adsorption ratio (SAR), 

control cation-exchange reactions between ground 

water and the functional groups in the coal. In 

general, the SAR for ground water is inversely 

proportional to the calcium content of the coal; a 

high SAR indicates a high sodium content. Large 

amounts of sulfate in ground water increase the 

availability of exchangeable sodium relative to calcium and magnesium without altering the concentrations of these cations. 

Ion exchange, governed by the ion concentrations in ground water, is the primary mechanism 

controlling the sodium content of coal deposits in 

the Powder River Basin. Chemical data obtained 

from carefully collected and properly analyzed 

26 
water samples from coal beds may eventually be 

used to predict the ash-fouling properties of the 

coal before mining. 

SEQUENTIAL TECTONICS OF THE 

WESTERN MARGIN OF THE POWDER 

RIVER BASIN, JOHNSON AND 

SHERIDAN COUNTIES, WYOMING 

E. Neal Hinrichs 

Recurrent movement on northeast-trending 

faults in the eastern Bighorn Mountains has offset 

mafic dikes of Archean age and thrust faults in 

Tertiary rocks of the western Powder River 

Basin. The largest component of movement on 

these faults is strike slip, which has accentuated 

the Piney lobe and offset the Clear Creek thrust 

fault. 

Sedimentary rocks exposed on the western edge 

of the asymmetric Powder River Basin total about 

5,180 meters in thickness and range in age from 

the Middle Cambrian Flathead Sandstone to the 

Eocene Wasatch Formation. Archean basement 

rocks are igneous and metamorphic, mainly 

gneiss, granite, and dikes and plugs of diabase, 

basalt, diorite, and pyroxenite. 

The largest structure in the area is a concealed 

high-angle reverse fault which was detected by 

seismic methods and reported by N. H. Foster, 

P. E. Goodwin, and R. E. Fisher in 1969. The 

fault, named the Buffalo Deep fault by D. L. 

Blackstone Jr., in a 1981 study, dips westward 

and has an estimated throw of 400 meters. Offset 

on this fault reaches to the top of the Fort Union 

Formation, but not into the Wasatch Formation. 

Other structures, moderately well to well exposed, have been investigated by many geologists, 

the first of whom was probably G. H. Eldridge, 

who in 1894 grouped the faults and folds into 

three blocks-northern, central, and southern. 

The northern and southern blocks show similar 

structures produced by compression from the 

northeast, namely asymmetric folds with steep 

southwest limbs and reverse faults that dip northeast. In contrast, the central block contains thrust 

faults and high-angle reverse faults that dip southwest. My detailed mapping in the central block 

shows the following sequence of deformation: (1) 

normal faulting with a dominant northeast trend 

followed by intrusion of mafic dikes during Late 

Archean time; (2) uplift of the Bighorn Mcuntains 

and high-angle reverse faulting of tilted Paleozoic 

and Mesozoic rocks during the Laramide orogeny; 

(3) thrust faulting during late Eocene; (4) strikeslip faulting, post-Eocene, with some re~'~urrent 

movement on Precambrian fault zones; (5) normal 

faulting mainly along traces of thrust faults, basin 

side down. 

The economic importance of this tectonism 

bears directly on the search for buried tr~ck deposits of coal and accumulations of oil and gas. 

The lack of sizeable coal deposits in the Fort 

Union Formation north of Crazy Woman Creek, 

mentioned by R. K. Hose, can be explained in 

part by differential uplift of the central block. This 

uplift diverted streams and shifted th ~ peat 

swamps. The search for oil and gas has prorrressed 

to testing unconventional traps, such as granite 

overthrusts, as in the Granite Ridge hole drilled 

by the Gulf Oil Company on the Piney lobe. Although this was a dry hole, it proved the low 

angle of the thrust fault. The well being drilled 

(1985) by Arco on the upper plate of the Clear 

Creek thrust may penetrate producing z1nes in 

the sediments beneath the granite. 

THREE STATISTICAL METHODS FOR 

ESTIMATING UNDISCOVERED RESOUR~1ES 

BASED ON THE MINNELUSA PLAY, 

POWDER RIVER BASIN 

J. Houghton, E. Attanasi, G. Dolton, L. r'rew, 

R. Mast, D. Root, and J. Schuenemeyer 

The Minnelusa play is used as a case study for 

three approaches to oil and gas resource estimation. The play, on the broad east flank of tl'~ Powder River Basin, Wyoming, includes about 150 oil 

fields in a suite of primarily stratigraphic traps, 

controlled by a regional unconformity and a regional seal. Trap morphology and size are controlled by paleotopography, reservoir truncation, internal formational variations resulting from depositional or diagenetic factors, and small str·lctures 

with stratigraphic overtones. 

Geographic limits to the play are un~ertain; 

however, industry exploration has defined a concentration of pools on the central east flanl< of the 

basin, with only a scattering outside that flank. 

A question remains whether the spatial d;o;1t;ribution of discoveries to 1985 is caused by geologic 

or econornic factors. The drilling data and field file 

27 
were developed and modified extensively from the 

Well History Control System (WHCS), PDS (Petroleum Data System) data, and published information. 

Each estimation technique relies on a different 

type of information and is adapted to a different 

scale. The first estimation technique is based on 

determining the area of interest to explorationists. The prospective area can be calculated 

from the drilling record, as an alternative to detailed geologic data, in basins where some exploration already has been done. The prospective 

area in the Minnelusa play is divided into two 

equal halves, early and late. These areas were delineated on the basis of the sequence of wildcat 

drilling in many diverse tracts. The first half delineated prior to 1966, has accounted for 90 'percent of the oil discovered and for 72 percent of 

the wells drilled. Extrapolation of the discovery 

rate in the first half indicates that the basin will 

produce ultimately 394 million barrels of oil. The 

average discovery rate for the second half has 

been only 19 percent of the discovery rate of the 

same number of wells in the first half. From these 

data and calculations, it is inferred that the ultimate production of the second half will be only 

75 million barrels and that the ultimate production 

from both halves of the delineated area will be 

469 million barrels, of which 381 million barrels 

have already been discovered. It appears, however, from analysis based on extrapolating the 

growth of the productive area as a function of the 

number of cumulative exploratory wells, that the 

undiscovered oil resources in the play are smaller 

than the previous inference. 

The second class of techniques is based on discovery process models, which were used to predict the expected volume of petroleum to be found 

by future wildcat wells. These models include the 

negative exponential extrapolation presented by 

Arps and Roberts (A-R) and two relatively newer 

models by Meisner and Demirmen (M-D) and 

Hinde and Forman (H-F). The M-D and H-F models assume that the size distribution of fields is 

lognormal and that the probability of finding a 

field is proportional to a discoverability coefficient 

estimated from past drilling and discoveries. 

Forecasts made by H-F and M-D are sensitive 

to the underlying equations describing probability 

of success and tend to give larger estimates than 

A-R, at least when the model of success probability is modified to better fit the empirical record. 

28 

Although H-F and M-D offer advantages, such as 

avoiding the problems associated l~rith an arbitrary choice of class size and yield estimates, the 

unit of exploratory effort needs to l: ~ determined 

exogenously and there is no prediction of the ultimate underlying field size distribution. None of 

these methods yields a forecast of more than 55 

million barrels of oil to be discoveref} in the play 

with the drilling of twice as many wildcat wells 

as have been drilled already in the pl::ty. 

A third method, which also uses the Minnelusa 

data, assists resource estimation in other areas. 

This technique uses less detailed data than a drilling record and relies more on geologic data and 

comparisons with mature analog regions. In this 

case, however, the larger fields in the Minnelusa 

play are used as a statistical analog for other 

plays. The Minnelusa field file contains 152 fields, 

of which 68 are larger than 1 million barrels. 

When fit by the Shifted Pareto (SP), a modification of the Pareto Distribution, the largest field 

is expected to be 55.6 million barrels, almost 

exactly the 51.7 actually discovered, and the rest 

of the sample fits almost as well. Th~ fitted curve 

has a thick right-hand tail-the pop~1lation coefficient of skew is infinite. The total amount of oil 

in the 68 fields, 377 million barrelf, is matched 

exactly. 

Based on geologic analogs and estimates of 

either the total amount of oil and gas or the size 

of the largest field, field size distrbutions from 

the Minnelusa and other already-ext: 1ored regions 

can be used to describe the likely properties of 

the field size distribution in a regior being assessed. This SP distribution allows an estimate of the 

expected size of each field, ordered by size; the 

amount of oil that would be reduced from the estimate by limiting the size of the largest predicted 

field; and those field sizes smaller th2 n the current 

economic cutoff. 

TERRANES, RESOURCES, ANI' THE 

GEODYNAMICS OF CONTINENTAL GROWTH 

David G. Howell and David L. Jones 

Continents increase in mass becaus~ of the addition of new material (primarily fragments of volcanic islands, seamounts, and hydr'lgenous and 

biologic sediments) formed in oceanic settings. 

Admixed with these are continental fragments 

and piles of terrigenous sediment; both of these 

affect continental recycling but not net growth. 
Ordovician Viola Limestone in rotated ramp anticline on north flank of Arbuckle anticline, on east-facing cut, Interstate Highway 

35. Original color slide by W. J. Perry, April1985. 

Terranes are the fault-bounded fragments of these 

materials found in orogenic belts. In the CircumPacific region, the rate of accretion since the 

breakup of Pangaea in early Mesozoic time is calculated as 2 to 2.5 km3/yr, or as much as 80 m3/s. 

An average global growth rate needed to account 

for the entire mass of continents (7.6x109 km3 ) 

since Early Archean time (3.8x 109 yr) is 2.0 km3/ 

yr; the flux of continental growth, however, remains a topic of great controversy. 

Although ocean crust contributes little to the 

mass of continents, the creation of ocean crust 

creates the "conveyor belt" that leads to the formation of sialic material; in addition the conveyor 

belt leads to the accretion and dispersive kinematics that result in the growth and shaping of continents. The isochrons deduced from magnetic 

stripes in the modern oceans (about 300x 106 km2 

in area) indicate an average age for ocean crust 

of only 70 m.y. Oceanic crustal rocks form at a 

rate of 800 m3/s assuming a 6-km-thick crust. If 

plate tectonic processes have been operative since 

29 

3.8 Ga, even at modern rates as many as 27 worldocean crusts would have been born at spreading 

centers and lost back to the mantle in subduction 

zones. 

The processes linking tectonics, sedimentation, 

and resources are not clearly understood, but as 

we learn more about the geologic and physical 

properties of terranes, as well as their kinematics 

and dynamic histories, our prospecting perspicacity should improve. Some explanations are already 

available: Campeche, the Persian Gulf, and 

Prudhoe Bay are all passive margin sequences tectonically overrun by foreland thrust and fold environs; southern California and the North Sea represent dispersive settings, transcurrent and orthogonal rifting, respectively. What other as yet untested conditions could house petroleum accumulations, for example, deep source gas in accretion 

piles associated with the subduction of sediment, 

or hydrocarbons locked in compressed flysch basins that are overridden by exotic terranes, 

. ? 
EVALUATING COMPOSITIONAL TRENDS IN 

MIOCENE-PLIOCENE STRATA OF 

SOUTH-CENTRAL COASTAL CALIFORNIA 

Caroline M. Isaacs, Kathleen C. Stewart, 

and Larry L. Jackson 

The Miocene Monterey Formation is the most 

prolific petroleum-source rock in California and 

locally an important petroleum-reservoir rock. Because of recent giant petroleum discoveries in 

fractured Miocene strata of offshore California, regional facies models of these strata are important 

to petroleum exploration and production. Of particular interest are the distributions of organic 

matter (which is the petroleum source), clay 

(which critically reduces fracturability and hence 

reservoir potential), and diagenetic silica and dolomite (both of which enhance fracturability). Our 

results suggest that quantitative determination of 

sedimentary components by chemical analysis of 

cuttings may prove valuable for determining regional facies patterns and evaluating regional 

source and reservoir potential. 

Regional synthesis of the Monterey Formation 

has proven to be difficult because Monterey strata 

are mainly uncommon, fine-grained biogenic 

lithotypes, Monterey depositional facies patterns 

are poorly understood, diagenetic patterns are unlike those in more widely studied sedimentary 

rocks, and well-log responses do not follow accepted interpretive rules. In the south-central 

coastal basins (Santa Maria, Santa Barbara-V entura, Huasna), another major difficulty in evaluation of the Monterey Formation is lithologic 

heterogeneity. Although Monterey strata in this 

area are mainly fine grained, lithotypes vary markedly on scales ranging from tenths of an inch 

(centimeter) to tens of feet (several meters). In 

terms of sedimentary composition, individual beds 

are widely scattered over the ranges 2-95 percent 

biogenically derived silica, 0-95 percent carbonate 

minerals, 5--80 percent terrigenous detritus, 0--25 

percent apatite, and 1-35 percent organic matter. 

Because the entire range of compositions is present in many stratigraphic intervals as thin as 6 

ft (2 m), the number of samples needed to determine a representative value is almost prohibitive. 

Thus identification of compositional trends 

through time (even in single sequences) is extremely difficult, and comparisons between sequences have been virtual guesswork. 

We have approached the problem of lithologic 

heterogeneity by chemical analysis of bulk cuttings samples, studying four wells as follows: (1) 

Hondo offshore oil field, Santa Barbara Channel 

(two wells); (2) Orcutt oil field, onshore Santa 

Maria basin; and (3) the Point Conception Deep 

Stratigraphic Test well (OCS-Cal 78--164 No. 1), 

"offshore Santa Maria basin." For each well, we 

evaluated Miocene and Pliocene strata ranging in 

thickness from 2,800 ft (850 m) to 7,000 ft (2,150 

m), by analyzing cuttings samples representing interval-averages of between 10 and 30 ft (3 and 

10m) of strata. 

Particularly important in evaluating the cuttings method is the Union Hobbs 22 well in the 

Orcutt field, where results can be compared with 

analyses of individual core samples from the 

nearby Union Newlove 51 well. In the uppermost 

Miocene and Pliocene Sisquoc Formation overlying the Monterey Formation, sedimentary component abundances are relatively uniform throughout a 1,000-ft (300-m) interval, and values based 

on eighteen 10-ft (3-m) interval averages (av detritus 66 percent, av silica 28 percent) are closely 

representative of values based on 12 core samples 

(av detritus 68 percent, av silica 27 percent). Also 

of importance in evaluating the method are results 

from 5,000 ft (1,550 m) of Miocene and Pliocene 

strata in the two wells in the Hondo area; the 

striking similarity of the compositional sequence 

confirms that cuttings analysis provides an excellent basis for detailed correlation. Our results thus 

indicate that quantitative analysis of cuttings provides representative compositional data which can 

identify major compositional trends, and the 

method should prove valuable for determining regional facies patterns and evaluating regional 

source and reservoir potential. 

GEOMETRY AND HYDROCARBON APPRAISAL OF 

THE PUTNAM THRUST ADJACENT TO THE 

SNAKE RIVER PLAIN NEAR BLACKFOOT, IDAHO 

Karl S. Kellogg, Frank R. Hladky3 , 

and George A. Desborough 

Late Tertiary basin-and-range extensional faulting about 10--20 km southeast of Blackfoot, Idaho, 

has broken the Putnam thrust to produce a com30 

aFrank R. Hladky, Department of Geology, Idaho State University, Pocatello, 

lD H3209. 
plex fault geometry. The Putnam thrust is considered to be the northern extension of the Upper 

Jurassic to Cretaceous Paris-Willard thrust system and plunges beneath upper Tertiary and 

Quaternary volcanic and sedimentary deposits of 

the Snake River Plain. 

Our studies, which extend previous work by D. 

E. Trimble of the U.S. Geological Survey, show 

that 

1. Strata from both the lower and upper plates 

of the Putnam thrust are gently to tightly folded 

and commonly overturned; 

2. Fault blocks are rotated as much as 60°, predominantly to the east, during late Tertiary extensional faulting probably younger than 10 Ma, 

as shown by attitudes on tuff, conglomerate, and 

limestone of the upper Tertiary Starlight Formation; 

3. The upper plate of the Putnam thrust in the 

Yandell Sprin~s 11/2-minute quadrangle includes 

strata as old as the Middle to Late Cambrian 

N ounan Limestone and as young as the Silurian 

Laket~;n Dolomite (both units previously unrecognized in the study area); 

4. Lower plate strata include the Upper Mississippian Monroe Canyon Limestone, the Lower 

Pennsylvanian to Lower Permian Wells Formation, the Permian Phosphoria Formation, and the 

Lower Triassic Dinwoody and Thaynes Formations; 

5. A window through the Putnam thrust is extensively broken by normal faulting, exposing 

lower plate rocks of the Wells, Phosphoria, and 

Thaynes Formations; 

6. Hydrothermal fluids, probably associated with 

volcanic activity along the Snake River Plain, 

have dolomitized many of the limestone units (notably from the N ounan and Lower Ordovician Garden City Formations) during the Tertiary; and 

7. As noted by Trimble, normal faulting extensively brecciated rocks of the upper plate of the 

Putnam thrust, particularly the Upper Ordovician 

Fish Haven Dolomite. 

The Meade Peak Member of the Phosphoria 

Formation is known to be a highly favorable hydrocarbon source rock in the Idaho-Wyoming 

thrust belt. At the Gay phosphate mine, in the 

eastern part of the study area, these strata are 

slightly beyond mature, rather than supermature 

(metamorphosed), as previously reported. The potential exists, therefore, for hydrocarbon generation after thrusting in this region. 

31 

ALLOCYCLIC CONTROLS ON THICK COAL 

DEPOSITION IN SEDIMENTARY BASINSSOME POWDER RIVER BASIN EXAMPLES 

lion H. Kent, Frances Wahl Pierce, 

Carol L. Molnia, and Edward A. Johnson 

Sedimentary basins form by subsidence and are 

filled by sediments eroded from opposing, uplifted 

source areas; many coal basins were tectonically 

active when coal-bearing rocks were deposited. 

The repeated episodes of tectonic subsidence and 

uplift that induced changes in climate, gro_und 

water, and base level also introduced fluctuatiOns 

in energy of distributary systems for sediment infill: high-energy episodes of clastic influx were interspersed with quiescent, low-energy periods of 

peat accumulation, causing basin rock-types to be 

repeated vertically in crude cyclic sequences. 

These allocyclic controls interacted to establish 

and prolong optimal environments and conditions 

necessary for thick peat to accumulate, to bury 

and preserve the peat beds beneath sediment 

cover and to increase depths of burial and sedi- ' . ment overburden. The nature of such control Is 

best described by a "teeter-board" hypothesis 

based on a simple assumption: if one area is subsiding while an opposing area is uplifted, a "fulcrum" area in between is in dynamic equilibrium. 

The Powder River Basin, Montana and Wyoming, is a product of Laramide structural movements. Some of the largest coal deposits in the 

world are in Tertiary rocks along the eastern flank 

of the basin. During middle Paleocene to Eocene 

time, high-energy clastic influx from eastern, uplifted source areas alternated with low-energy 

periods of thick peat accumulation. Pivotal effects 

of western (basin) subsidence and eastern (Black 

Hills) uplifts produced linear fulcrum areas in dynamic equilibrium, elongate north-south across the 

west-tilted paleoslopes that formed the eastern 

flank of the developing basin. During quiescent 

periods, when subsidence and uplift were subdued 

and sediment infill was minimal, the linear fulcrum areas became broad centers for peat accumulation. Fulcrum areas (centers for peat accumulation) were shifted west by eastern uplifts 

and east by western subsidence. Several fulcrumarea migrations occurred in response to subsidence and uplift over a prolonged period. The overall migratory shift was westward, ahead of the 

succeeding episode of clastic influx that buried the 

peat beds. 
c.:> 

t-:) 

SW 

PROFILE B 

FEET 

500 

400 

22 ' 

300 

200 

100 

•::""'" · 15 Miles---------; 

'KNOBLOCH' COAL DEPOSIT 

(Middle Paleocene) 

N PROFILE A s 

------ - -----30 Miles--------- --- ---

PATTERNS OF COALS AND SANDY INTERVALS 

w PROFILE C 

/ ./ / n 

' ' / 

/ / 

/ / 

/ / 

/ / 

u ---- IJ' ,. / / 

.; / 

/ 

/ 

/ 

10Miles 

WYOOAK COAL DEPOSIT 

(Late Paleocene) 

w 

/7 

PROFILED s 

Xw x, 

y l ;/~ ~ ..... _ __ . -:.'-111111F '' 

,!' 

500Ft 

' ' 

,{ 

' " g" 

/• ' 

" Hc•• H / '/ 

' 20 Miles 

FELIX COAL DEPOSIT 

!Eocene I 

400 

300 

200 

tOO 

E 

FIGURE I.-Profiles, chronology, and features of thick coal deposition in Paleocene and Eocene rocks along the eastern flank of the Powder River Basin, Montana and 

Wyoming. Tf, Fort Union Formation (Paleocene); Tw, Wasatch Formation (Eocene). 

Ft 
Figure 1 illustrates chronology and characteristics of thick coal deposits in Paleocene and Eocene 

rocks along the eastern flank of the Powder River 

Basin. Profile A (fig. 1), of upper Paleocene coals 

and sandy intervals, is oriented north-south approximately parallel to the depositional strike; the 

profile illustrates how quiescent periods of thick 

coal deposition were interspersed with high-energy episodes (labeled 1, 2, 3, 4 and 5) of sediment 

infill from eastern source areas. Successive 

episodes of clastic deposition exhibit the familiar 

offset-stacking pattern that characterizes fluvial 

architecture. Laterally continuous coal beds separate those sandy intervals (see profile A, fig. 1). 

The east-west profiles (B, C, and D, fig. 1) illustrate some characteristics of thick coal deposits. 

Closely associated coal beds merge locally to form 

single beds of combined coal and the thickest 

single bed of combined coal forms the central core 

of the deposit. The central cores of the "Knobloch" 

(profile B) and Felix (profile D) coal deposits split 

eastward to thin upper benches and thick lower 

benches, and westward to thick upper benches 

and thin lower benches, suggesting fulcrum-area 

migration and overall migratory shift westward. 

As indicated on profile C (fig. 1), upper Paleocene 

rocks containing the Wyodak coal deposit were 

uplifted, tilted westward, and beveled to the central core of the deposit prior to the advent of Eocene sediment cover; consequently, an unconformity separates Paleocene rocks from Eocene rocks 

and only the western half of the Wyodak coal deposit is preserved in the rock record. 

In the Powder River Basin examples, the 

geometries of thick coal deposits illustrate allocyclic controls and provide a model for analogs in ancient and modern settings. 

CONTINENTAL MARGIN MAPPING PROJECT, 

UNITED STATES ATLANTIC MARGIN-A 

SYNTHESIS OF GEOLOGIC AND 

GEOPHYSICAL DATA AND INTERPRETATIONS 

Kim D. Klitgord and Gary H. Hill 

Syntheses of geologic and geophysical studies 

on the United States Atlantic continental margin 

are being compiled in a series of maps and a digital database. Both map and digital forms are being 

used to facilitate the transfer and use of the extensive information acquired by the U.S. Geological Survey on the United States continental margins. For this project, the Atlantic margin has 

been divided into four regions: Georges Bank 

basin and Gulf of Maine, Baltimore Canyon 

trough, Carolina trough, and Blake Plateau basin. 

Each region extends from the seaward edge of the 

U.S. Exclusive Economic Zone to the Coastal 

Plain onlap (Fall Line) onshore. Primary data sets 

for this series have been derived from multichannel seismic-reflection profiles, magnetic surveys, 

and gravity surveys as well as drill hole and bottom sample data. 

Mapping is being done on an Albers Conic 

Equal Area Projection using standard parallels of 

lat 29.5° N. and 45.5° N., at a scale of 1:1 million, 

and will be compatible with the National Atlas 

geologic map and tectonic map of the United 

States. Individual maps in the series comprise topography and bathymetry, tectonic features, 

isopachs of various sedimentary units, depth contours of basement and various sedimentary surfaces, paleoenvironment, magnetic-anomaly contours, and gravity-anomaly contours, as well as 

drill-well locations, seismic-line navigation, and 

offshore leases. 

THERMAL EVOLUTION OF KEROGEN AND 

PHYTOCLASTS IN THE EASTERN 

UNITED STATES EARLY MESOZOIC 

BASINS AS A GUIDE TO MATURATION 

R. K. Kotra, R. M. Gottfried, E. C. Spiker, 

P. G. Hatcher, and A. J. Froelich 

Kerogen and phytoclasts (coalified plant fragments) from the sedimentary rocks in exposed 

early Mesozoic basins of the Newark Supergroup 

in the Eastern United States are currently under 

study; we are using several organic geochemical 

techniques to discover the thermal history and 

sources of the organic matter in the host rocks. 

Solid-state C-13 nuclear magnetic resonance spectroscopy, pyrolysis-gas chromatography, stable 

isotope ratios. and vitrinite reflectance are being 

applied to compare the nature of the organic matter in phytoclasts and kerogen derived from lacustrine shales. Assessments of kerogen maturity can 

be influenced by the source of the parent organic 

matter. The rank of phytoclasts (known to be of 

vascular plant origin) from the same rock can provide an additional or independent measure of the 

degree of heating. 

33 
Uranium ore from an Arizona breccia pipe showing uraninite in matrix surrounding bleached sandstone breccia clasts. Largest 

clast is 5 em in length (photo from 1985 study by K. Wenrich and J. Rasmussen). 

The composition of the preserved organic matter in the samples examined so far is quite variable. The rank of phytoclasts ranges from that of 

subbituminous coal to that of anthracite with no 

relation to age or to apparent depth of burial. This 

implies that other factors, such as hydrothermal 

activity, may have played an important role during maturation. Phytoclasts recovered from zones 

of copper mineralization, for example, are consistently highly altered, indicating a high degree of 

thermal stress possibly associated with hydrothermal activity. Kerogen associated with phytoclasts, 

as well as kerogen from shales devoid of phytoclasts, was examined primarily to determine its 

source. The data showed that the composition of 

kerogen varies widely. Some samples showed 

characteristics similar to sapropelic kerogen (such 

as from shales in the Green River Formation); 

others appeared to be composed of humic kerogen 

derived from vascular plant remains. 

These preliminary organic geochemical investigations show that the organic matter in the lacustrine strata of the Eastern United States early 

Mesozoic basins exhibits varying degrees of thermal maturity and has varying source compositions. Attempts to determine the oil and gas po34 

tentials of these shales must take into consideration the regional variabilities of these factors. 

EXPERT SYSTEMS RESEARCH AND 

ITS APPLICATION TO ENERGY STUDIES 

Katherine B. Krystinik 

Expert Systems, or Knowledge-Based Systems, 

have high potential for aiding in energy research. 

Expert systems derive strength from the incorporation of both factual and heuristic, or "rules-ofthumb," knowledge. 

Expert systems are being constructed within 

the U.S. Geological Survey to aid in the interpretation of depositional environments, a key component of sedimentary basin analysis and the analysis of regional geologic trends. Particular environments or several closely related depositional environments are represented by expert systems 

which incorporate the understanding of an expert. 

This work is an excellent application for expert 

systems techniques for several reasons: (1) a representative problem can be solved in a reasonable 
amount of time; (2) recognized experts exist but 

are often not readily accessible; (3) numerous 

practical applications for these systems exist. 

An expert system for beach deposits, developed 

in conjunction with H. Edward Clifton, illustrates 

how depositional environments are identified. 

Lithofacies characteristic of a particular environment are interpreted from observed features of 

the outcrop or core; these features include lithology, sedimentary structures, bioturbation, and so 

on. The user volunteers information in response 

to questions asked by the system during a consultation. Uncertain responses are allowed and incorporated into the reasoning. The user is able to 

obtain additional information on each of the questions or the reasoning used in asking them. The 

dialogue varies in different consultations because 

the questions asked by the system depend upon 

the responses of the user to previous questions. 

At the end of the consultation, the system 

evaluates the likelihood that the deposit under 

consideration indicates a particular depositional 

environment. The reasoning used by the system 

in reaching the conclusion is accessible to the user. 

Appropriate references are easily added. 

· Systems of this sort are useful as aids in consulting and teaching as well as for documenting 

heuristic knowledge. The documentation facilitates comparison of several experts' models for 

one depositional environment as well as comparison across depositional environments. The depositional environment expert systems can serve as 

the basis for a more extensive system, potentially 

including knowledge from other geologic specialties, for example, log analysis. 

FLUID MIGRATION PATHWAYS-EVIDENCE 

FROM THERMAL MATURITY MAPPING IN 

SOUTHWESTERN WYOMING 

B. E. Law, M. R. Lickus, and M. J. Pawlewic.z 

Regional thermal maturity investigations in the 

Greater Green River basin of Wyoming, Colorado, 

and Utah, funded by the U.S. Department of Energy's Western Tight Gas Sands Program, have 

facilitated the identification of fluid migration 

35 

pathways and provided specific information bearing on the origin of the Patrick Draw oil and gas 

field in southwestern Wyoming. 

Vitrinite reflectance CRm) data from Upper Cretaceous and Tertiary subsurface samples of coal 

and carbonaceous shale, siltstone, and s~mdstone 

in the Greater Green River basin show several 

areas wherein levels of organic maturatior are abnormally high with respect to regional levels. One 

of these areas centers on the Patrick Dr~w field 

and is subparallel to a northeast-trending zone of 

faults. Rm values in the upper Cretaceous Almond 

Formation range from 0.48 percent immQdiately 

adjacent to the abnormally high a rea to 

0.68 percent within the area. An isoreflectance 

line superimposed on a structural cross sert;ion extending from the southwestern part of th~ Green 

River Basin, east-northeast through the Patrick 

Draw field to the Rawlins uplift, shows that the 

dip of the isoreflectance line is generally le~,~ than, 

or equal to, the structural dip. However, in the 

vicinity of the Patrick Draw field, the dip of the 

isoreflectance line is greater than the st~ctural 

dip, indicating that the organic matter in this area 

has been subjected to higher temperatures than 

in adjacent areas. 

We believe that this and other similar r.reas of 

abnormally high levels of thermal maturit~T in the 

region occur as a result of hot fluids coming into 

contact with organic matter, elevating tr~ level 

of thermal maturity above regional levels. In the 

specific example of Patrick Draw, we sugg~~st that 

the hot fluids were hydrocarbon bearing, having 

originated from pre-Almond source rocks located 

in a more basin-centered position. In resp·mse to 

hydrocarbon generation and expulsion, hot, hydrocarbon-bearing fluids migrated to structurally 

higher positions along the Wamsutter arch. where 

faults and fractures provided vertical pathways. 

As the fluids flowed upward along fault and fracture surfaces, hydrocarbons entered the porous 

and permeable reservoirs of the Almond Formation and accumulated in stratigraphic traps. The 

passage of these hot fluids through the faul~.ed and 

fractured rocks is indicated by abnormar:~ high 

levels of organic maturation. The example: of the 

Patrick Draw field illustrates how thermal maturity investigations can apply to problems c1ncerning fluid migration. 
AN APPLICATION OF AZIMUTHAL 

VERTICAL SEISMIC PROFILES 

M. W. Lee 

An azimuthal vertical seismic profile (VSP) is 

defined as seismic measurements inside a borehole 

from sources located in azimuthal directions relative to the borehole. One of the advantages of an 

azimuthal VSP is that it can identify subtle stratigraphic horizons and their spatial distribution 

near the well site. The VSP method is of particular importance when the surface seismogram is of 

poor quality, due to low seismic frequency or severe surface static and noises. 

An azimuthal VSP technique has been used 

near Rifle, Colorado, to investigate the lateral extent of lenticular sand bodies in the Mesaverde 

Group. A high-resolution, three-dimensional seismic survey was conducted in this area previously, 

but the surface seismic data were not effective in 

delineating the lenticular-type sand bodies in this 

study area. Thus, an azimuthal VSP experiment 

was carried out at the U.S. Department of Energy Multi-Well Experiment site in April 1984. Two 

wells were profiled with a tri-axial, three-component downhole geophone and a 450 in. 3 (7,374 cm3) 

surface airgun source at four different source locations. Due to poor ground conditions, airgun malfunctions, and time limitations, the data quality 

was only fair. 

After careful data processing, however, the 

seismic character of the lower coastal sand bodies 

could be identified. Interpretation of the spatial 

distribution of sand bodies was based mainly on 

the laterally stacked vertical component of the 

VSP data, in conjunction with one- and three-dimensional seismic modeling, and a geological interpretation in 1985 work of J. C. Lorenz. 

Individual sand bodies were difficult to delineate due to the lack of high-frequency content 

of the conventional VSP data. However, the lower 

coastal sand bodies (Yell ow and Red zones of J. 

C. Lorenz, 1985) could be mapped. The Red sand 

trends northeast with an average width of 800 ft 

(240 m), whereas the Yellow sand trends northwest with an average width of 600 ft (180 m). This 

investigation suggests that azimuthal VSP surveys can detect and delineate finite-extent bodies, 

such as reservoirs. 

LASER MICROPROBE "FINGERPRINT~~G'' AND 

ORIGIN OF ELEMENTS IN VITRITr BANDS 

FROM SELECTED COAL BEDS OF 

EASTERN UNITED STATES 

Paul C. Lyons, John J. Morelli4 , 

David M. Hercules4 , Curtis A. Pnlmer, 

Floyd W. Brown, Janet D. Flet1-:her, 

and Marta R. Krasnow 

Vitrinite is the major maceral group found in 

Carboniferous coal beds of Eastern United States; 

thus, most of the major chemical and physical 

properties of these coals are probal~ y related to 

this microconstituent. Macerals of the vitrinite 

group are commonly thought to have originated 

from woody tissue which underwent degradation 

and other chemical changes before and during 

diagenesis. These chemical changes are assumed 

to have resulted in the mobilization. enrichment, 

and entrapment of certain elemerts and compounds available from the degradinr peat tissue, 

pore fluids, and mineral matter in the peat and 

surrounding strata. 

The distribution of elements and compounds in 

a suite of vitrinites was analyzed with a laser 

microprobe (LAMMA), supplemented by analyses 

by neutron activation and d. c. arc s'"1ectrographic 

techniques. LAMMA is a state-of-the-art mass 

microanalyzer capable of detecting all isotopes and 

elements in the parts per million range and compounds up to masses of 2,000 amu (atomic mass 

units). Detection limits are in the parts per billion 

range for certain elements such as N a, K, and F. 

We selected vitrinites (generally banded telinites) from nine coal beds in Ea~tern United 

States, ranging in rank from high volatile C 

bituminous coal to meta-anthracite, to be analyzed 

by LAMMA. H/C atomic and R0 max reflectance 

data were used to generate a rank series of the 

vitrinites. For each coal bed, three ,.ritrinite sites, 

generally within the same vitrite band and several 

hundred or more micrometers apart, were 

analyzed by LAMMA; a total of 12 analyses were 

averaged for each site. 

Of elements analyzed, N a and Fe were detected 

in all vitrinite bands examined; LL Mg, AI, Si, 

K, Ca, Ti, Sr, and Ba were comrr.only present; 

P, S, Se, Zr, Mn, Ga, As, Bi, Ni, Cr, Co, V, 

Sc, Cu, Zn, La, Ce, F, and Cl were hss commonly 

or rarely detected by LAMMA. Pyritic sulfur is 

4

John J. Morelli, David M. Hercules, Department of Ch~mistry, University of 

Pittsburgh, Pittsburgh, PA 15260. 

36 
detected by LAMMA as S +, Fe+, FeS +, FeS2 +, 

Fe2S +, and Fe2S2 +. In mixtures of pyrite and 

macerals, most of the sulfur in pyrite is usually 

detected as SH, as opposed to sulfur, due to the 

availability of hydrogen from LAMMA micropyrolysis. 

Presence of several elements detected by 

LAMMA was confirmed by instrumental neutron 

activation or spectrographic analysis of bulk vitrinite concentrates from dne samples. The following ranges in concentrations were detected by 

neutron activation techniques (in ppm): K ( <100--

650), Na (50--600), Ba ( <30--106), Sr (17--89), Zn 

(3-24), As (0. 7-12), and Cr (2-23). Iron ranged 

from 510 to 4,190 ppm; this large range is most 

likely due to pyrite impurities in the concentrates. 

Ni and Co (<2-10), B (<20--79), Mn (<20--40), and 

Ti (76--300) were determined in two concentrates 

by d.c. arc spectroscopy. The same technique determined Pb (34), Ge (5), V (14), and Zr (9) in 

one of the concentrates. 

These data indicate that vitrinite in each vitrite 

band analyzed yielded a distinctive suite and concentration of elements. In each of two coal beds 

where different vitrite bands or grains were 

characterized by LAMMA, the same "fingerprint" 

was obtained. Further work is necessary to determine if the elements found within a given vitrite 

band (which may represent some particular plant 

organ, such as a petiole) originated from the original plant matter or from secondary processes before or during diagenesis. 

The results of this study indicate the usefulness 

of LAMMA as a new microprobe technique for organic and inorganic qualitative analysis of coal. 

LAMMA procedures offer rapid detection and 

data reduction, detection of both organic and inorganic compounds, moderate to high sensitivity for 

all elements, and surface cleaning by preliminary 

laser bursts to minimize surface contamination. 

AN INTEGRATED APPROACH USING THE 

COMPUTER IN THE GEOLOGIC ASSESSMENT 

OF HYDROCARBON RESOURCES 

OF THE POWDER RIVER BASIN, 

WYOMING AND MONTANA 

Richard F. Mast, James E. Fox, 

and Gordon L. Dolton 

Independently created computer data files can 

be used together in assessing the hydrocarbon re37 

source potential of oil and gas plays in the Powder 

River Basin, Wyoming and Montana. The approach we have used should be equally useful in 

other hydrocarbon-productive basins. 

Using geologic data from approximately 200 of 

the deepest, strategically located oil and gas wells 

in the basin, we constructed a series of 20 eastwest electric log cross sections. On these cross 

sections, formation tops, key bentonite beds, 

major unconformities, and stratigraphic pinchouts 

were identified to illustrate stratigraphic relationships of Upper Cretaceous through Pennsylvanian 

and, in some cases, deeper strata in the basin. 

We then loaded the geologic data on these cross 

sections into a computer file that includes well 

identification, location, elevation, and depth from 

the surface to the top of all major stratigraphic 

units, selected bentonite beds, and major unconformities. With this data file, the computer compiled regional isopachs of important hydrocarbon 

source-rock and reservoir-rock units, as well as 

generalized structure contours. 

Geologic data files were also retrieved using all 

drill holes from the Well History Control System 

(WHCS). These WHCS data were independently 

verified to remove obviously spurious information 

from the well file and to add new information. The 

computer then was able to generate a series of 

structural contour compilations showing wildcat 

penetrations of several of the major oil- and gasrelated units in the basin. 

From the results of the geologic analysis, a 

series of oil and gas plays in the basin were described, geographically delineated, and their 

boundaries digitized to provide a framework for 

managing and editing stratigraphic and geographic data for use in resource assessment 

studies. Drill holes, oil and gas fields or pools, and 

oil and gas shows were then mapped for the included oil and gas plays using the data retrieved 

from the WHCS. Drilling statistics were compiled 

for the 30,000 exploration and development wells 

in the basin and for each of the oil and gas plays. 

Finally, an example oil and gas field-data file 

was created for the Minnelusa play using several 

sources, summarizing published data for each 

pool. This file contains information on 142 separate pools discovered through 1981. It characterizes the geologic properties of each reservoir, 

and it gives size data for pools, which were in 

part generated or verified by extrapolating ultimate recoveries from production data. This file allows for display and analysis of such variables as 
The Bat Cave breccia pipe (northern Arizona) forms a prominent 800-ft (250-m) vertical column along 

cliff face. Pipe is located just south of the Colorado River, principally in lower part of the Supai 

Group and upper part of the Redwall Limestone. Photograph by K. J. Wenrich, March 1983. 

38 
porosity, reservoir thickness, depth, and oil gravity. 

Computerized data management and display 

systems made it possible for all of the geologic, 

drilling, and discovery data to be integrated and 

cross- checked. Integration and analysis of the 

geologic, drilling, and field or pool discovery data 

are valuable tools in the assessment of exploration 

maturity of oil and gas plays and the appraisal 

of future oil and gas resources. 

GLORIA SIDESCAN-SONAR SURVEY 

OF THE WESTERN MISSISSIPPI 

FAN INTRASLOPE BASINS 

B. A. McGregor, J. S. Schlee, and K. D. Klitgord 

The U.S. Geological Survey has just completed 

a long-range sidescan survey within the U.S. Exclusive Economic Zone in the Gulf of Mexico, 

using the GLORIA II sidescan system of the Institute of Oceanographic Sciences of Great Britain. Portions of this survey concentrated on the 

slope-rise region of the central Gulf of Mexico 

where the Mississippi Fan laps onto the salt diapir 

province of the Texas-Louisiana continental slope. 

Numerous Pliocene-Pleistocene intraslope sedimentary basins have been formed in this area by 

the dynamic interaction between salt tectonics, 

sea-level fluctuations, and sediment-loading, as 

described in a 1983 study by A. H. Bouma. The 

shallowest of these intraslope basins are within a 

zone referred to as the Gulf deepwater flexure 

trend and are already target~ for petroleum exploration. The combination of sidescan sonar imaging 

and seismic-reflection profiling is being used to 

map in detail the areal extent and distribution of 

these intraslope basins and to study the sedimentary deposits within the basins. Between long 89° 

W. and 90.5° W. the intraslope basins have received substantial terrigenous input from the Mississippi Fan system and have a morphology that 

resembles stepped terraces. The intraslope sedimentary basins west of about long 90.5° W. are 

also bathymetric basins. 

Surface reflectivity of the sediment fill within 

the blocked-canyon intraslope basins contrasts 

with the reflection character of the faulted relief 

and bathymetric steps associated with the salt 

diapirs or ridges and possible collapse basins. 

39 

These surficial acoustic reflectivity contrr ~ts provide excellent imaging targets for the sidescan 

sonar. Variations in seismic-reflection character 

with depth below the sea floor are being used to 

map lithologic variations within the basin~. Sidescan data and seismic-reflection data are being integrated into a combined study of prer~nt and 

past sediment deposition patterns. 

TECTONICS AND THE POTENTIAL FnR 

HYDROCARBONS IN OFFSHORE BASil ~$ OF 

WESTERN NORTH AMERICA 

Hugh Mclean 

The enormous volumes of unexplored sedimentary rock that lie beneath and adjacent to the continental shelves of Alaska and the Pacific coast 

area of the lower 48 States provide an attractive 

target for exploration, as the United States' longterm demand for domestic hydrocarbon reserves 

increases. Tectonic setting strongly affects the 

probability of oil and gas hydrocarbon ge~eration, 

migration, and entrapment in the intra-shelf and 

shelf-edge basins. 

Basins on the Beaufort and Chukchi sl...elves of 

Alaska lie along a rifted or passive mar~n, and 

are filled with as much as 12 km of Jurassic and 

younger strata. On the Bering shelf, several basins formed and filled during Tertiary time in response to transtensional stress and (or) oroclinal 

bending between Asia and North America. Structures within the Bering shelf basins te:'ld to be 

gentle low-amplitude folds related to draping over 

basement topography. The Aleutian Bas~n lies in 

waters deeper than 2,000 m and contains an 

enormous volume of sediment ponded behind the 

Aleutian archipelago. Along the transforr portion 

of the basin margin, sediment thickness locally exceeds 9 km. Small basins on the crest of t.he Aleutian Ridge formed in response to exten<>ion and 

contain as much as 4 km of Neogene fill. 

Shelf and slope basins of the Aleutif.n Ridge 

(which extends from the Komandorsky Islands to 

the Gulf of Alaska) formed in response to Tertiary 

plate convergence. Structures within these basins 

tend to be complex, with older fill often overlying 

melange generated by accretion. Prospective 

rocks are generally Neogene in age. 
Southeastern Alaska is a region of Cenozoic 

transform plate motion where the northward-moving Pacific plate is being subducted beneath the 

eastern end of the Aleutian arc in the Gulf of 

Alaska. Where these two tectonic domains join 

lies a zone of highly complex structure, in the 

apex of the Gulf of Alaska. Plate convergence also 

dominates the region from Vancouver Island, 

southward along the Washington, Oregon, and 

northern California coast to the Mendocino triple 

junction. Along this segment of the Pacific margin, basins are mainly filled with Neogene beds 

that overlie structurally complex accreted sedimentary and volcanic rocks. 

Central and northern California shelf basins 

formed in response to dextral Neogene transform 

movement between the North American and 

Pacific plates. Exploratory drilling in the 1960's 

indicates that some of the basins contain oil-bearing siliceous shales that may be similar to the 

Monterey Formation, which is now producing oil 

in the giant Arguello field. 

The California Continental Borderland has several large bathymetric basins that contain prospective Neogene sediment sequences that wedgeout against basement ridges. Recent exploratory 

drilling in Upper Cretaceous and Paleocene strata 

on Santa Rosa-Cortes Ridge has produced disappointing results, because of poor reservoir rocks 

and immature source rocks. 

Geologic trends of southern California extend 

into Mexico: shelf basins of northern Baja California are mainly filled with Neogene strata that overlie Franciscan-like accretionary rocks in the 

west and Cretaceous batholithic and older prebatholithic basement in the east. Central and 

southern Baja California is dominated by a Late 

Cretaceous and Paleogene forearc basin filled with 

siliciclastic sediment resembling Great Valley 

rocks. Exploratory drilling onshore and offshore 

indicates that potential source rocks are immature 

throughout the area; the source-rock immaturity 

reflects insufficient burial owing to long-term vertical tectonic stability of the granitic core of the 

Baja peninsula. 

Despite immense volumes of sedimentary rock 

in waters less than 200 m deep, fewer than 120 

rank wildcat wells have been drilled in Federal 

waters of the Western United States (Cook Inlet, 

Santa Maria, and Santa Barbara Channel 

excluded). In contrast, more than 550 wells have 

been drilled in the State of Oregon alone. Realistic 

40 

assessments of petroleum potential can only be 

made when drilling provides data on source-rock 

volume, quality, and maturity, and the depth and 

age of porous and permeable reservoir rocks. 

SEDIMENTOLOGY AND TECTONIC SEniNG OF 

INTERMONTANE TERTIARY COAL-BEARING 

ROCKS, SOUTHWESTERN MONTANA 

J. M'Gonigle, M. Kirschbaum, anr' J. Weaver 

The intermontane Medicine Lodge and Horse 

Prairie basins of southwestern Mo'ltana are located between the Bitterroot Range on the west 

and south and the Tendoy-Pioneer Mountains on 

the east and north. The Medicine Lodge (ML) 

basin is adjacent to the Tendoy Mourtains and lies 

east of the Horse Prairie (HP) basin; ML basin 

joins with the northern part of HP basin, but is 

separated from the southern HP bas:~11 by a northtrending spur of the Bitterroot Ran.5e, composed 

mainly of granite gneiss locally over1ain by Paleozoic sedimentary rocks. These basinr, covering an 

area of about 825 km2 , contain as much as 3,000 

m of Eocene(?) to Miocene volcanic and sedimentary rocks. We mapped Tertiary rocl·s in the ML 

and southern HP basins as part of a study of coal 

depositional environments. 

The oldest Tertiary sedimentary r<'(!ks in the region, preserved mainly in the Tendcv Mountains, 

are those of the syntectonic Paleocen~ Beaverhead 

Conglomerate, deposited during the SevierLaramide orogeny. Following erosion, extensive 

Eocene(?) volcanism in the region deposited as 

much as 760 m of andesitic lavas, tuff, and rhyolite in the ML and HP basins. Af~.er a second 

period of erosion, Oligocene(?) fluvial and lacustrine sediments filled the basins. An areally restricted but thick (360 m) freshwater limestone 

deposit in the southwestern part of the ML basin 

represents an open lacustrine facies that interfmgers to the north with a marginal-lacustrine facies 

composed of shale, some conglomeratic sandstone, 

and carbonaceous shale and coal. Subsequent uplift caused the erosion of some of these sediments 

in the basins and the deposition of an alluvial fan 

sequence (as much as 427 m thick in the ML basin) 

in slight angular unconformity on tl' ~ older sediments. Highlands to the south or west, where 

Tertiary volcanic rocks had been deposited directly on Proterozoic Belt sedimE:.ntary rocks, 
served as source areas for the clasts in the fans. 

The fanglomerates represent mid- and distal-fan 

facies, and grade laterally into a fluvial sequence 

(braided to meandering streams) of coarse conglomeratic to medium-grained sandstone and associated coal-bearing shaly swamp deposits. The 

bulk of the coal in the two-basin area is contained 

in the ML basin in these swamp and fluvial deposits, in beds averaging about 0.3-1.0 m thick. 

The swamp and fluvial deposits grade upward into 

a 1,250-m-thick open lacustrine facies of thin-bedded shale, tuffaceous shale, and minor limestone 

containing fish, ostracode, and plant fossils of Oligocene-Miocene age. These lacustrine deposits, 

which represent the reestablishment of a lake in 

the ML basin, can be mapped around the northern 

end of the spur into the HP basin, where they 

pass laterally into alluvial fill of mudstone, shale, 

and sandstone. 

The basal Eocene(?) volcanic sequence and the 

overlying sedimentary sequence in the ML basin 

are identical to sequences in the HP basin, on the 

other side of the now mountainous north-trending 

gneissic spur separating the two basins. As no 

clasts of the gneiss that makes up the spur are 

found in the fanglomerates, and as the Tertiary 

beds now flanking the spur are everywhere tilted 

and (or) disrupted by faulting, it seems clear that 

the spur was exposed and eroded in post-Miocene 

time. Remnants of the volcanic sequence and overlying sedimentary rocks on differentially displaced structural blocks of Precambrian gneiss 

along the western side of the Tendoy Mountains 

indicate relative uplift of the Tendoys or ML basin 

subsidence by at least 3,000 m after Miocene time. 

These facts suggest that a single Tertiary basin 

was ancestral to the ML and HP basins, and that 

it probably once extended across part or all of the 

present northern Tendoy Mountains. The ancestral basin very likely also encompassed the areas 

of other nearby intermontane Tertiary basins, 

such as the Cabin Creek valley to the south, the 

Muddy Creek basin to the southeast, and perhaps 

the Big Hole basin to the north. 

ANALYSIS OF SEISMIC REFLECTION 

LINES OVER PACIFIC CONVERGENT MARGINS 

J. J. Miller and R. E. von Huene 

the many diffractions that mask primary structure 

and because the true geometrical relatio"lships of 

steeply dipping faults and folded strata are distorted in standard, stacked record sectjons. We 

reprocessed data acquired over the eastern Aleutian Trench and the Middle America T1·ench off 

Guatemala and Peru using wave-equatio'1 migration techniques that were not available 'vhen the 

data were initially processed. 

Wave-equation migration, applied after stacking, improved the quality of the structural information by eliminating diffractions. As we attempted to improve data quality further, we d~veloped 

a processing scheme consisting of migrathn-velocity analysis performed on stacked record sections, 

migration applied before stacking, and res tacking 

using stacking velocities determined after migration. We generated depth sections by applying refraction velocities observed in various geologic 

units to the equivalent units interpreted on the 

time sections. 

The quality of all the resulting stackei record 

sections improved significantly because migration 

had eliminated diffractions and reposition ~d faults 

and folds into their true geometrical confirruration. 

Specific improvements in resolution include (1) reliable stacking velocities of primary reflections 

previously masked by diffractions, (2) recognition 

of landward- and seaward-dipping fault-plane reflections in the Aleutian Trench, (3) recognition 

of gas hydrate reflections off Peru, (4) sh<:l.rp definition of the boundary between accreted trench 

and sea-floor sediment and the truncated edge of 

the Peruvian continental crust, and (5) precise 

definition of decollements separating the subducted from the offscraped sediment sedions in 

all the lines. 

The processing procedure we developed requires additional man-hours and much c'lmputer 

time. However, the improvement in quali~y of the 

resulting seismic image is sufficient to ju:;-tify the 

use of this procedure in areas of complex ~:eology. 

THERMAL-ENERGY STORAGE IN A 

CONFINED SANDSTONE AQUIFER 

AT ST. PAUL, MINNESOTA 

R. T. Miller 

The U.S. Geological Survey has been studying 

Seismic reflection data recorded over conver- the hydrologic effects of storage and recovery of 

gent margins are difficult to interpret because of heated water in a deep sandstone aquifer in St. 

41 
Paul, Minnesota, since 1980. The USGS has designed a data-collection network, determined the 

hydrogeologic properties of the aquifer, conducted 

tests of hot-water storage cycles, and constructed 

computer models to simulate ground-water flow 

and thermal-energy transport. 

The Aquifer Thermal Energy Storage (ATES) 

system, the data-collection network, uses a doublet-well design, with both wells completed in the 

Franconia-Ironton-Galesville aquifer. Water is 

pumped from one of the wells through a heat exchanger, heat is either added or removed, and the 

water is injected back into the aquifer through the 

other well. The injection/withdrawal wells are 

spaced 250 m apart. 

Analysis of constant-rate, aquifer-test data indicates that the aquifer has four hydraulic zones 

that are areally anisotropic and whose average hydraulic conductivity ranges from 0.03 to 1.2 

meters squared per day. Borehole-geophysical 

data indicate that the aquifer is horizontal and of 

uniform thickness between the injection/withdrawal wells. Laboratory analyses of core samples 

indicate that aquifer porosity ranges from 14 to 

35 percent. 

The experimental plan for testing the ATES 

system consisted of a series of hot-water injection, 

storage, and withdrawal cycles. Short-term tests 

consisted of four cycles approximately 24 days 

long, with each injection, storage, and withdrawal 

step of the cycle lasting approximately 8 days. A 

long-term-test cycle of 180 days consisted of 60 

days each of injection, storage, and withdrawal. 

Several computer models have been used to 

study the sensitivity of hydraulic and thermal 

model-input properties, to make preliminary 

evaluations of efficiency of the aquifer system, and 

to simulate the four short-term and one long-term 

experimental test cycles. Sensitivity analyses indicate that, in short-term heat injection, rock-heat 

capacity is the least sensitive property and thermal dispersivity the most sensitive. Preliminary 

model simulations indicate that injection/withdrawal rates and duration of heat storage can significantly affect the overall efficiency of the 

aquifer-thermal system. The period of simulation 

for modeling the short-term cycles was equal to 

the entire time period over which the four cycles 

were conducted, including periods between individual cycles. Model-computed aquifer-thermal efficiencies, defined as the total energy recovered 

divided by the total energy injected for equal 

pumping durations and rates, and final temperatures at the hot-water storage well were within 

plus or minus 2 percent and plus o1· minus 5°C, 

respectively, compared to those rec~'>rded in the 

field. Model simulation of long-term test cycles required an increase in the areal descritization to 

account for a larger area of stored heat. Field-recorded aquifer-thermal efficiency ani final wellhead temperatures were 68 percent f.nd 67°C, respectively, while model simulation gave aquiferthermal efficiencies and final well-hc~d temperatures of 67 percent and 68°C, respectively. 

ENHANCED ANALYSIS OF TRACE··ELEMENT 

CHARACTERISTICS OF BITUMINOf JS COALS 

USING THE PROTON (PIXE) MICr~PROBE 

Jean A. Minkin, E. C. T. Ch~o, 

and Herma Blank5 

Microprobe methods have proven to be valuable 

techniques in coal-quality studies, for example in 

in-place direct determination of organic sulfur content in coal macerals, and modes of occurrence of 

such elements as As, Se, N a, and Cd. In routine 

electron probe microanalysis (EPMA), the practical lower limit of detection for most elements is 

about 100 ppm. Therefore, the development of 

microprobes based on proton-induced X-ray emission (PIXE) has provided an important extended 

capability for quantitative determination of elemental concentrations in individual maceral and 

mineral grains: the detection limit for the analysis 

of most elements using the proton microprobe is 

1-10 ppm. 

We were encouraged by the results of our first 

PIXE study (1982), on vitrinites in a series of vitrites, selected from along the length of a single 

drill-core sample (M1) of the J and I coal beds 

of the Ferron Sandstone member of the Mancos 

Shale, Emery County, Utah. We therefore 

selected two companion drill cores, M3 and M5 . ' for similar analysis, to examine trace-·element variations laterally as well as vertically. Locality M3 

is separated from M1 by approximately 3, 700 ft 

(1,125 m), and M5 is an additional 4,350 ft (1,300 

m) in the same direction from M3. In addition, 

vitrites from selected depth intervals of a columnar section of Upper Freeport coal from Indiana 

County, Pa., and a columnar section of No. 6 coal, 

Webster County, Ky., were analyzei to develop 

preliminary profiles of trace-element variation 

6Herma Blank, Institut Laue-Langevin, F~ Grenoble Cedex, France. 

42 
with depth and compare the data for these eastern 

coals with those of the U tab coal. Analyses were 

all carried out on vitrinite group macerals because 

the vitrinite content in all these coals is generally 

about 80 volume percent or more. Hence, vitrinites are probably the major source of trace elements attributable to macerals in these coals. 

Trace-element characteristics of the three U tab 

drill-core samples are generally similar to one 

another. Most notable is the consistent general 

trend of increase in iron concentration (unrelated 

to iron sulfide) from top to bottom of the I coal 

bed ( <20 to about 1,400 ppm). There is a parallelism of variation in elements such as Ti, Zr, and 

Cr in vitrinite for the three cores, which in turn 

resembles the trends for Si and AI determined by 

EPMA, suggesting that these elements are 

largely associated with submicroscopic clay particles. In the Upper Freeport coal bed, V, Cr, Ni, 

Zn, Ga, and Ge are all present at higher concentrations in vitrinites from near the bottom of the 

bed than near the top, at the one location studied. 

No obvious systematic trends or variations were 

noted for the Kentucky No. 6 sample. Bromine 

is present in the two eastern coals at higher concentrations (Upper Freeport about 100 ppm and 

Kentucky No. 6 about 20 ppm) than in the U tab 

coal ( < 1 ppm), while Sr is generally higher (30--

300 ppm) in the U tab samples than in the eastern 

samples (10--30 ppm). 

These examples of data obtained illustrate the 

sensitivity of detection obtainable with the proton 

microprobe in analysis of coal macerals. Such data 

will be important in tracing the geochemical conditions of deposition and diagenesis of a coal bed, 

and in assessing potential applications and problems of combustion, gasification, or liquefaction of 

particular coals. 

REGIONAL CORRELATION SECTIONS ACROSS 

THE NORTH SLOPE OF ALASKA 

C. M. Molenaar, K. J. Bird, and T. S. Collett 

Since the discovery of the giant Prudhoe Bay 

field in 1968 and the subsequent exploration in 

northern Alaska, new data have added immensely 

to the understanding of the stratigraphy of rocks 

underlying the North Slope coastal plain. The 

stratigraphic section consists of two sequences, 

the northern-derived Ellesmerian sequence and 

the overlying southern- and southwestern-derived 

43 

Brookian sequence. The Ellesmerian S"'QUence 

consists of (1) Mississippian through Triasric semistable platform carbonate and clastic roc1

rs, zero 

to 2,500 m thick; (2) southward-progradhg shelf 

to basinal Jurassic to earliest Cretaceous shales, 

zero to 1,100 m thick; and (3) less thar 100 m 

of northward-transgressing Hauterivian-Barremian (Early Cretaceous) shale with a k"t}ticular 

basal sandstone that unconformably overlia.s progressively older rocks to the north. 

The Brookian sequence displays much greater 

time-transgressive facies relationships across the 

North Slope than does the Ellesmerian s€quence. 

It is an easterly to northeasterly prc~ITading 

wedge of Aptian(?) (Lower Cretaceous) through 

Tertiary clastic rocks as much as 4,000 m thick. 

In ascending order, this sequence consists of (1) 

less than 300 m of Aptian(?) to Maestrichtian 

basinal shale and bentonite, the lower part of 

which is generally organic rich; (2) as nuch as 

3,000 m of Albian to Eocene basin-slope or prodelta shale with turbidites in the lower p·n-t; and 

(3) as much as 2,400 m of Albian to Quri;ernary 

shallow marine and nonmarine deltaic and alluvialplain sandstone, shale, and conglomerate. A network of regional well-correlation sections across 

the North Slope, based in part on micropaleontologic and seismic data, shows that thesA different facies of the Brookian sequence are coeval 

with each other across depositional strike, and 

that most of the nomenclature established in the 

western North Slope is not applicable to the eastern North Slope. 

COMPUTERIZED ASSESSMENT OF THE COAL 

RESOURCES AND GEOLOGY OF 

THE SAN JUAN BASIN, NEW MEXICO 

Carol L. Molnia, Antoinette L. Medlin, 

Kathleen K. Krohn, Joseph T. O'Con•'~r, 

Laura H. Biewick, Nancy K. Gardnnr, 

and Lewis W. Boger 

The National Coal Resources Data System 

(NCRDS) of the U.S. Geological Survey recently 

produced resource estimates, and accompanying 

computer-generated illustrations, for a ~tudy of 

coal in the San Juan Basin, New Mexico. This 

study is part of a larger study of the coal resources and coal quality in the State of New 
Mexico, done in cooperation with the New Mexico 

Bureau of Mines and Mineral Resources. 

A working data base of stratigraphic information on the Cretaceous Fruitland and Menefee 

Formations, the two major coal-bearing units 

within the San Juan Basin, was retrieved from 

the NCRDS master data base for New Mexico by 

use of the PACER data storage and retrieval system on a 32-bit minicomputer. These data were 

reviewed for consistency and correctness, additional data were coded and added, and retrievals 

were then made for drill holes that penetrated the 

entire thickness of the Fruitland or Menefee Formations, within the digitized boundary areas. 

The coal resources for both formations were calculated from this data set in GARNET, one of 

the graphic analysis and volume calculation software systems of NCRDS. In addition, the same 

Fruitland Formation coal data set was analyzed 

by the geostatistical method, kriging. Because of 

the lenticular nature of the coal beds and the large 

area under study, the resource assessments were 

not made for individual coal beds but rather for 

total coal in a formation. 

The GARNET software uses a point file location, a grid file of coal thickness, and a boundary 

file to calculate the volume of coal; then, the density factor for the rank of coal is applied to produce a coal tonnage estimate. By this method, the 

Fruitland Formation is estimated to contain 168 

billion short tons of coal and the Menefee Formation is estimated to contain 21 billion short tons 

of coal, within the New Mexico part of the San 

Juan Basin. The estimate was presented in three 

ways: as a single resource tonnage; as measured, 

indicated, inferred, and hypothetical category tonnages; and as tonnages in various land ownership 

and overburden categories. 

The kriging method considers the spatial variability of data and produces estimates which are 

unbiased and have minimum error variance. Total 

in-place coal resources estimated by this method 

for the Fruitland Formation are 160 billion short 

tons, which is within 5 percent of the GARNET 

estimate. The kriging method was also used to 

help design future data collection programs by optimizing the location of sample points; hypothetical 

drill-hole locations were added to the kriged data 

set for assessment of their impact on the precision 

of the estimate. 

In addition to the actual resource calculations, 

the study produced several computer-generated illustrations of the geology of the San Juan Basin. 

A color graphics package that rrodels stratigraphic surfaces in three dimensions was used to 

display, through interlocking panel~ in various 

orientations, the interval containing the Kirtland 

Formation, Fruitland Formation, P:~·~tured Cliffs 

Sandstone, and the Lewis Shale and its Huerfanito Bentonite Bed. Illustrations of the structure of the basin on the base of the Dakota Sandstone were also developed, as was a correlation 

diagram for the Fruitland coal zone. The GARNET software was used to illustrate generalized 

land ownership patterns as well as t(' contour coal 

isopachs and overburden. 

AN EXPLORATION MODEL BAf~D ON 

A GENETIC MODEL FOR TI'E 

TABULAR-TYPE VANADIUM-URANIUM 

DEPOSITS IN THE HENRY BASI.~. UTAH 

H. Roy Northrop, Fred Peterson, 

Gene Whitney, and Martin B. G~ldhaber 

The sandstone-dominated Salt Wash Member of 

the Upper Jurassic Morrison Formation hosts 

tabular-type vanadium-uranium derosits in the 

Henry basin, Utah. The deposits are, in general, 

typical of vanadium-uranium deposits in the Colorado Plateaus province. Previous 'vork allowed 

us to construct a genetic model of these deposits 

and to identify a number of key aspects of the 

ore-forming process that can now be combined to 

make a simple yet precise exploratioll model. 

The key features of ore genesis a1·e as follows: 

1. Vanadium-uranium mineralization occurred at 

and immediately below a nearly basin-wide density-stabilized brine-meteoric water interface that 

migrated up stratigraphic section with time. 

2. Economic vanadium-uranium deposits formed 

in intrabasinal synclines. 

3. Detrital organic matter, which vras preferentially preserved by specific sedimentological controls, was a necessary component of the mineralizing process. 

4. Uranium was leached from the }'':lSt rocks up 

paleohydrologic gradient and up stratigraphic section from the deposits, and enriched down the 

paleohydrologic gradient from the largest deposits. 

The mineralogic fingerprint left by the brinemeteoric water interface, organic-eiJriched sandstones, intrabasinal synclines, and r'1cks leached 

of uranium are geologically identifir.ble features 

44 
Core drilling on a patch reef in Enewetak lagoon. Diver operates drilling equipment that is powered by hydraulic pumps 

in RV HALEMIDA, 10m overhead. Diver: J. Harold Hudson. Photograph by R. B. Halley. 

that define deposit locations. Dolomite and a vanadium-bearing clay mineral formed in direct response to the brine-meteoric water interface 

throughout the basin, thus marking the peneconcordant stratigraphic intervals where the 

mineralizing reactions occurred irrespective of 

uranium ore grade. Detrital organic matter was 

preserved close to black, organic-rich mudstones 

deposited in small anoxic lakes. These lakes occurred at the low-energy end of the Salt Wash 

fluvial system. The brine-meteoric water interface 

was sharply defined within intrabasinal synclines, 

whereas mixing of the brine and meteoric water 

over intrabasinal anticlines resulted in a poorly 

defined solution interface. These diffuse solution 

interfaces reduced the effectiveness of the vanadium-uranium concentrating reactions, and prevented ore-grade mineralization on the anticlines. 

Large-scale uranium distribution patterns 

throughout the basin are useful because rocks 

leached of uranium are a necessary part of the 

ore-forming process. Th: U ratios are a very sensitive indicator of this uranium removal. 

Elements of our exploration model involve taking the geologically identifiable features associated 

with each key aspect of the ore genesis model to 

identify successively smaller targets. Initially, 

identification of potential source rocks leached of 

uranium on the up-paleohydrologic side of a basin 

not only identifies a required process but also defines a large-scale target. The location of suitable 

intrabasinal synclines through detailed sedimentologic and stratigraphic studies then defines possible sites for vanadium-uranium concentration. 

This effort yields somewhat smaller scale targets. 

The distribution of those mudstones with associated organic-matter-enriched sandstones is 

predictable by sedimentological analysis, yielding 

even smaller targets. At that point, detailed 

mineralogy defines each interval that hosted a 

brine-meteoric water interface. The limits of 

orebodies are defined where this interval projects 

across the organic-enriched sandstones. 

CONTROLS ON DISTRIBUTION OF ORE IN 

SO-CALLED "UNCONFORMITY· TYPE" URANIUM 

DEPOSITS IN AUSTRALIA AND IMPLICATIONS 

FOR UNITED STATES URANIUM RESOURCES 

C. J. NuH, David Frishman, R. I. Grauch, 

J. T. Nash, and K. R. Ludwig 

The Jabiluka and Ranger "unconformity-type" 

uranium deposits in the Pine Creek geosyncline, 

Australia, are hosted by metasedimentary rocks 

of the Early Proterozoic Cahill Formation and are 

beneath the regional unconformity separating 

these metamorphic rocks from the overlying sandstones of the Middle Proterozoic Kombolgie Formation. U-Pb radiometric ages show that at Ranger, primary ore formed more than 1,720 m.y. ago, 

well before deposition of the Kombolgie Formation (1,648 Ma) and contemporaneous with a 

period of postorogenic granitic intrusions. The 

Jabiluka deposit formed about 280 million years 

later, during a period in which no major thermal 

event has been recognized. 

In both deposits, uranium ore occurs in breccias 

and veins and as disseminations in intensely 

chloritized pelitic, in places graphitic, schists. 

45 
Brecciation has previously been attributed to collapse following solution of carbonate, but at 

J abiluka siliceous breccias that occur in or adjacent to graphite schist and along the contact 

separating carbonate and graphite schist retain 

textures indicative of tectonic origin. We propose 

that brecciation is largely the result of brittle deformation and is particularly concentrated in 

siliceous interlayers in the graphite schist and 

along the contact separating carbonate and schist. 

Faulting and silicification coupled with carbonate 

collapse also brecciated the rocks at Ranger. 

Alteration at the two deposits is similar and 

occurs in both the metasedimentary rocks and, to 

a lesser extent, in the overlying sandstone. Magnesium-rich chlorite is the most prominent alteration mineral in these deposits, but apatite, tourmaline, white mica, and quartz were also introduced. At Ranger the alteration is more intense and primarily restricted to the orebodies, 

whereas at Jabiluka the alteration is more pervasive and extends far into the surrounding rocks. 

Cross-cutting relations among chemically distinguishable chlorites testify to the influx of numerous pulses of fluid with different and probably 

evolving compositions. Although alteration is most 

intense in the ore zones, much of the observed 

alteration occurred after uraninite deposition and 

only locally redistributed preexisting ore. 

Ranger's pre-1, 720 Ma age indicates that the 

unconformity and overlying sandstone played no 

role in primary concentration of the ore, although 

the Kombolgie no doubt helped preserve the deposit from later erosion. At the younger J abiluka 

deposit, the role of the unconformity and the rocks 

above it is less clear, however, and whether or 

not the lithology of the cover rocks is important 

is as yet unresolved. J abiluka possibly contains remobilized uranium, perhaps from a preexisting 

Ranger-type deposit, that was preferentially concentrated in the brecciated areas. 

Because they are both large and high grade, 

"unconformity-type" deposits have been very attractive exploration targets for the last 15 years. 

Numerous areas in the United States have been 

investigated for this type of deposit, including the 

terrane beneath the Jacobsville Sandstone in 

Michigan and the area beneath the Sioux Quartzite in Minnesota and South Dakota. In both these 

areas, the major similarity to productive "unconformity-type" districts is simply the existence of 

a fluvial Proterozoic sandstone. However, know46 

ing that the sandstone was, in at least one case, 

irrelevant to primary ore deposition makes areas 

like those mentioned much less favorable for deposits similar to Ranger. Conversely, the apparent structural control on localization of ore at 

J abiluka and Ranger implies that structure in the 

metasedimentary sequence may be a more relevant constraint on exploration strategies and resource assessment than the mere existence of an 

unconformity. 

DISCRIMINANT ANALYSIS OF TRACE ELEMENTS 

IN COAL BEDS OF EARLY AND MIDDLE 

PENNSYLVANIAN AGE FROM THE 

CENTRAL APPALACHIAN BASIN 

J. T. O'Connor 

Sixty-two of the sixty-three trace elements 

analyzed for coal samples as part of the U.S. 

Geological Survey Coal Geochemistry program 

were examined using the Fisher discriminant 

analysis technique, to determine if distinguishing 

geochemical characteristics exist for the coal beds 

of the Lower and Middle Pennsylvanian section 

of the Central Appalachian basin. Analyses were 

selected representing all samples (channel, bench, 

composite, grab, and core) with relatively low 

( <20 percent) ash content and were converted to 

an ash basis prior to examination. In order to assure that all samples were analyzed with comparable techniques, accuracy, and precision, only the 

more recent (later than July 1, 1975) samples from 

the USC HEM file of the National Coal Resources 

Data System data base were utilized. Elements 

with fewer than 50 percent unqualified analyses 

were dropped from consideration; elements with 

fewer than 75 percent unqualified analyses were 

examined carefully before inclusion or exclusion 

from the study. Other qualified analyses were converted from trace, less-than, greater-than, blank, 

not-reported, or interference qualifications according to U.S. Geological Survey protocol. Stratigraphic sample-population distribution ultimately 

restricted this study to analysis of samples from 

the Pocahontas No.3, Pocahontas No.4, Pocahontas No. 6, Eagle, and Sewell coal beds. 

Using the discriminant analysis technique, the 

author was able to distinguish unique geochemical 

differences between all of the coal sample groups 

studied. Twenty-four Eagle coal samples were dis-
tinguished from 26 Sewell coal samples with no 

exceptions and a very high significance test; the 

primary discriminating elements selected by the 

technique were Ce, Se, Ta, Zr, Sr, and B. Fiftytwo Pocahontas No. 3 and No. 4 coal samples 

were distinguished from 24 Eagle coal samples 

with no exceptions and a very high significance 

test; the primary elements selected by the technique were B, Ga, Pb, Co, Ce, and Sc. Fifty-two 

Pocahontas No. 3 and No. 4 coal samples were 

distinguished from 26 Sewell coal samples with 

one exception and a high significance test; the primary elements selected by the technique were Y, 

B, Se, Sc, Zn, and Th. Thirty-seven Pocahontas 

No. 3 coal samples, 15 Pocahontas No. 4 coal samples and 7 Pocahontas No. 6 coal samples were 

distinguished from each other with no exceptions 

and a moderately high significance test. The primary elements selected by the technique were Se, 

V, Ni, Ag, Co, and La. 

The discriminant analysis technique provides 

the coal geochemist a useful tool for determining 

unique geochemical characteristics of coal beds out 

of extensive collections of trace-element data. 

Such geochemical characteristics should aid the 

coal geochemist studying differences· in depositional environments existing at the time of coal 

bed formation and should help to correlate "orphan" coal beds with those for which geochemical 

data exist. 

INDUCED SEISMICITY AND THE 

STATE OF STRESS AT THE 

GEYSERS GEOTHERMAL AREA, CALIFORNIA 

D. H. Oppenheimer 

Previous studies of temporal and spatial distributions of seismicity at The Geysers, California, 

geothermal field demonstrated that activities related to steam withdrawal induced earthquakes. 

To gain insight into the inducing mechanism, the 

stress field at The Geysers was investigated 

through an analysis of 210 earthquake fault-plane 

solutions determined from P wave first motions. 

The earthquakes were recorded by the U.S. 

Geological Survey's Central California Seismic 

Network for the period April 1984 through May 

1985. The suite of earthquakes spanned the depth 

range of 0.1 to 5.4 km and were located from at 

least 15 observations out to epicentral distances 

of60 km. 

Induced earthquake activity at The Geysers occurs on fault planes whose orientations vary 

greatly over epicentral distances as small as 1. 0 

km. Estimates of the orientation and relative 

magnitudes of the principal components of the 

stress field show that the vertical component of 

the stress field exceeds that of the horizontal 

below a depth of 1 km. This results in depth-dependent fault-plane solutions whereby the earthquakes at depths less than 1 km mostly exhibit 

strike-slip to reverse mechanisms, whereas deeper 

earthquakes show increasing tendency for normal 

mechanisms. Below 2 km depth The Geysers appears to be undergoing uniaxial extension with the 

axis of extension oriented at approximately 106° 

azimuth. 

The good agreement between the local stress 

field below 1 km calculated from seismic data and 

that inferred from regional geodetic networks indicates that the regional tectonic stress is much 

larger than the stresses induced locally through 

geothermal production activities. The presence of 

large depositional basins to the north-northwest 

of The Geysers, together with normal focal 

mechanisms determined at The Geysers and the 

Konocti Bay fault zone, suggests that extension 

occurs over the entire region between the 

Maacama and Bartlett Springs fault zones. It is 

difficult to attribute this extension at The Geysers 

to tectonics associated with typical pull-apart basins because no basins are evident in the regional 

topography and extent of the master strike-slip 

faults is not known. However, regional extension 

is compatible with the wide-spread presence of 

Quaternary volcanism in the Clear Lake area. 

These results still do not establish the earthquake-inducing mechanism. However, the data 

permit a rather detailed description of the style 

of faulting and location of earthquake activity with 

respect to geothermal well positions. They indicate that the activity above a depth of 3.5 km occurs within several hundred meters of the wells 

and likely occurs in the immediate vicinity of fractures supplying steam to the wells. The most 

likely mechanism involves stresses induced by reservoir contraction, due either to pore collapse of 

the reservoir rock as water migrates out into the 

permeable fractures, or to thermal contraction resulting from production-related pressure declines 

in the reservoir. The large amount of seismicity 

below 3. 5 km depth reflects either steam communication between the wells and deeper regions 

of the geothermal reservoir through an extensive 

fracture network, or stress perturbations induced 

via reservoir contraction at shallower depths. 

47 
Divers pass camera during photo-documentation of patch reef in Enewetak lagoon. Studies of modern depositional environments 

provide a basis for comparison with similar ancient deposits that are reservoirs for hydrocarbons. Divers: J. Harold Hudson 

(left); Eugene A. Shinn (right). Photograph by R. B. Halley. 

STRUCTURE AND PETROLEUM POTENTIAL OF 

PALISADES ROADLESS AREA, IDAHO-WYOMING 

THRUST-BELT SALIENT NEAR 

JACKSON, WYOMING 

StevenS. Oriel and David W. Moore 

The U.S. Forest Service Palisades Roadless 

Area encompasses 386 square miles of the Snake 

River Range and lies along the northern end of 

the Idaho-Wyoming salient of the Cretaceous and 

early Paleogene Cordilleran foreland thrust belt 

southeast of the eastern Snake River Plain. The 

Teton Range fault block abuts the area on the 

north; Jackson, Wyoming, lies 7 miles east of the 

area's northern boundary. Bounding the area on 

the southwest are Swan and Grand Valleys, within the Neogene Swan Valley graben. The Snake 

River Range lies between the Salt River Range, 

on the south, and the Big Hole Mountains on the 

north. 

48 

Geologic mapping, begun in 1980 and recently 

completed, confirms the presence of successively 

structurally higher (from northeast to southwest) 

and older thrust sheets including the Jackson, 

Darby, Absaroka, and St. John allochthons. Several discontinuously exposed thrust slices (with 

various local names) are exposed on the southwest. The complexly folded and imbricately 

faulted thrust sheets consist of southwestwardthickening, mainly continental shelf strata, from 

the Cambrian Gros Ventre Formation to the coalbearing Cretaceous Frontier Formation; these 

lithostratigraphic units are identical to those in 

the petroliferous southern part of the IdahoWyoming thrust-belt salient. Anticlines and fault 

wedges exposed within the Snake River Range resemble proven subsurface structural traps defined 

in the southern Fossil basin (southwesternmost 

Wyoming) by both seismic reflection surveys and 

drilling. Moreover, favorable additional structures 

plunge beneath exposed thrust faults. 
Our studies do not support the presence of the 

north- to northeast-dipping Cache Creek thrust 

fault, inferred by others to underlie Teton Pass. 

If the fault were there, Mesozoic and upper Paleozoic strata beneath it would constitute potential 

hydrocarbon exploration targets. However, 

Neogene strata mapped by us are cut by northwest-trending extensional faults at Teton Pass, 

and synorogenic detrital evidence for movement 

on the Cache Creek fault is absent. We conclude 

that the Teton Range fault block, containing very 

thin cratonic Paleozoic and Mesozoic cover rocks, 

was broken and rotated toward the Snake River 

Plain volcanic rift long after the far thicker thrust 

belt strata were juxtaposed upon it by thrusting; 

the range formed as the crust was extended to 

form the Snake River Plain from Miocene time 

on. 

Hydrocarbon source beds, potential reservoir 

strata, fluid seals, structures, and hydrocarbon 

thermal maturities within thrust sheets of the 

Palisades area are comparable to those in large 

producing oil and gas fields in southwesternmost 

Wyoming and northern Utah. Moreover, eastward 

thinning and facies changes of both continental 

shelf strata and the overlying Mesozoic 

synorogenic units make stratigraphic traps probable in many strata which dip predominantly to the 

west. The petroleum potential for the Palisades 

area is thus high, in thrust sheets of the Snake 

River Range south of Teton Pass. 

MOVEMENT AND FIXATION OF URANIUM ON 

ORGANIC MAnER IN A LATE 

QUATERNARY URANIUM DEPOSIT, 

STEVENS COUNTY, WASHINGTON 

James K. Otton and Robert A. Zielinski 

Studies of a recently discovered, ore-grade accumulation of uranium in upper Quaternary, organic-rich sediments have provided a rare opportunity to study the movement and fixation of uranium in a natural setting. The deposit is hosted 

by valley-fill sediments that underlie the north 

fork of Flodelle Creek, in Stevens County, 

Washington. These sediments are as much as 5 

m thick and rest on glacio-fluvial sediments 

12,000--13,000 years in age. The local country rock 

is a two-mica quartz monzonite which is mostly 

covered by glacial drift. 

Waters moving through these organic-r~~h host 

sediments are derived from seasonal runoff in the 

4.2-km2 drainage basin or from springs on the 

slopes and the valley floor. Stream, spring, and 

shallow ground waters in the valley-bottcm sediment contain 17--318 ppb uranium---com{:f.l.red to 

a regional background of 1-2 ppb. No oth~r measured major or trace chemical species are as concentrated. Values for pH range from 5.85 to 7.55. 

The high concentrations of dissolved uranium, absence of H2S odor, and the presence of d:Qsolved 

nitrate are compatible with mildly oxidizin5 conditions. In filtered water samples, a high covariation 

of uranium with the major cations (Ca2+, Na +, 

and Mg2+), major anion (HC03-), total d:~solved 

solids, and conductivity all suggest that uranium 

is carried in a dissolved form. Uranium C

1

oes not 

correlate with dissolved organic carbon. Thermodynamic calculations indicate that uranyl carbonate and phosphate are the major ir--lrganic 

aqueous complexes. Factor analysis of th?. water 

data and reanalysis of more finely filtered samples 

indicate that some uranium is carried by colloidal 

particles of clay, organic matter, and hydrous iron 

oxides. Calculations of mineral solution eouilibria 

suggest that the measured waters are undersaturated with respect to uranous- and uranyl-bearing 

minerals if the ambient Eh exceeds 0.1 vo]\ Compared to coexisting waters, peat collected near the 

present surface of the deposit sedimentr is enriched in uranium several thousandfold, i"l quantitative agreement with predictions based on a 

sorption-ion exchange model in a 1964 study of A. 

Szalay. 

Chemical analyses of sediments from 72 intervals in 4 cores as much as 2. 9 m deep indicate 

uranium contents that vary from <100 to 4,470 

ppm, and that correlate strongly (r=0.8622) with 

organic matter (0.5-60 percent dry weigri;, estimated by loss on ignition). R-mode factor analysis, 

chemical variation diagrams, and depth profiles of 

measured species indicate that uranium c1ntents 

are largely controlled by the relative pror'lrtions 

of uranium-enriched organic matter and ur·aniumpoor detrital mineral matter. Virtually all other 

chemical species are controlled principally by the 

relative abundances of the three major detrital 

components: light minerals such as feldspar and 

quartz, heavy minerals such as iron and t:tanium 

oxides, and volcanic ash. Total sulfur c1ntents 

tend to covary with organic matter and uranium 

content in the shallow parts of all the corer, How49 
ever, deeper in some cores sulfur and uranium 

values are higher than would be expected from 

the relatively low organic matter content, 

suggesting that sulfur species may be affecting 

uranium content locally. 

Fission-track radiography of thin sections of organic matter in the sediment and uranium contents of various size fractions of peat indicate that 

uranium preferentially associates with finegrained, structureless organic matter, suggesting 

that surface area and degree of humification of organic matter are important controls on uranium 

fixation. 

The results to mid-1985 support a working 

hypothesis that peat in the shallower parts of the 

system initially adsorbed uranium. Ongoing 

studies of sulfur speciation, bacteria, and degradation of the organic matter focus on possible reduction mechanisms of uranium in lower parts of the 

deposit. 

ACCRETION, SUBDUCTION, AND UNDERPLATING 

IN SOUTHERN ALASKA-INITIAL 

RESULTS FROM THE 

TRANS-ALASKA CRUSTAL TRANSECT 

Robert A. Page, David L. Campbell, 

George Plafker, Gary S. Fuis, 

Warren J. Nokleberg, Elizabeth L. Ambos, 

Walter D. Mooney, and Michael A. Fisher 

The Trans-Alaska Crustal Transect (TACT) is 

a major U.S. Geological Survey project aimed at 

determining the structure and evolution of the 

Alaskan crust along a north-south corridor paralleling the trans-Alaska pipeline and extending 

offshore across the Pacific and Arctic continental 

margins. Begun in the summer of 1984, TACT 

work to mid-1985 has incorporated geologic mapping, petrologic and geochronologic studies, seismic refraction/wide-angle reflection profiling, and 

gravity and magnetic investigations. Vertical reflection profiling and magnetotelluric sounding will 

begin in 1986. The transect was launched in the 

Chugach Mountains and Copper River Basin in 

southern Alaska; over the next 5 years it will proceed northward to Prudhoe Bay and across the 

continental margins. 

50 

In the first two seasons, TACT investigations 

focused on three abutting accreted terranes and 

the underlying shallow lithosphere. From south 

the north, the terranes are (1) the Prince William 

terrane (PWT), composed of an accreted Paleocene and Eocene deep-sea fan complex, oceanic 

volcanic rocks, and pelagic sedirr~nts; (2) the 

Chugach terrane (CGT), composed of accreted 

Upper Cretaceous flysch and oc~anic basaltic 

rocks, accreted and subducted(?) Upper Jurassic 

to Lower Cretaceous sheared melange, and subducted(?) Lower(?) Jurassic or olc,er blueschist/ 

greenschist; and (3) the composite Wrangellia/ 

Peninsular terrane (WRT/PET: , consisting 

primarily of upper Paleozoic andefitic arc rocks 

with associated mafic and ultranafic plutonic 

rocks, an overlying Triassic sedime"ltary and volcanic sequence, and superposed intrusive and extrusive magmatic rocks of the Jura~sic Talkeetna 

arc. 

The PWT is thrust relatively northward beneath the CGT along the Contact fault system, 

and the CGT is thrust at least 40 km northward 

beneath the WRT/PET along the F<lrder Ranges 

fault system. At the southern margin of both the 

CGT and WRT/PET, shallow high-velocity bodies 

(depths >2-3 km and 1 km; Vp=6.8-7.1 km/s and 

6.1-6.4 krnls, respectively) characte~zed by magnetic and gravity highs reflect uplif: of mafic and 

ultramafic basement along these thrr1sts. The Border Ranges fault system apparentl:T soles into a 

subhorizontal low-velocity layer of uncertain origin flooring the northern CGT and the southern 

WRT/PET at about 7-9 km depth. The Contact 

fault system may sole into a deeper, gently north 

dipping low-velocity layer at abC'11t 9-12 km. 

Three additional north-dipping low-velocity layers 

are defined between about 15 and 35 km depth 

beneath the CGT. We interpret the four dipping 

low-velocity layers and the subjacent high-velocity 

(Vp=7.8--8.3 krnls) layers as S'lbducted assemblages of oceanic crust and mantle rocks. 

Based on the occurrence of earthquakes in the 

lower two assemblages, we infer that active subduction involves the lower two as~emblages and 

that the upper two have been unc ~rplated onto 

the continental plate. 
BOREHOLE GEOPHYSICAL APPLICATIONS 

IN THE CHARACTERIZATION OF 

GEOTHERMAL ENERGY RESOURCES 

F. L. Paillet, R. H. Morin, and W. S. Keys 

Borehole geophysical measurements represent 

an important technique for the evaluation of geothermal resources, but the hostile environment 

and complex geology of geothermal reservoirs 

make progress in geothermal logging quite slow. 

Geophysical logs are especially useful because 

they characterize rock properties at in-place conditions. Continuous well logs provide the resolution required to identify sets of fractures and lowpermeability caprock layers that may be less than 

a few meters thick. This continuity and spatial resolution are required to incorporate discontinuous 

core intervals and surface geophysical data into 

a consistent reservoir model. 

Ongoing research in geothermal well logging 

can be separated into three components: (1) development of equipment capable of withstanding 

the high temperatures, large pressures, and corrosive fluids encountered in geothermal reservoirs; (2) understanding the geophysical response 

of conventional and nonconventional logging devices to spatially complex patterns of geochemical 

alteration; and (3) improving methods for identifying and characterizing fractures in sedimentary, 

igneous, and metamorphic rocks. Significant progress in all aspects of geothermal-logging research 

is expected when a proposed deep borehole in the 

Salton Sea basin of southern California becomes 

available in late 1985. Maximum temperature in 

this 3,000-m-deep well is expected to be about 

370°C; dissolved-solids concentrations of the brine 

are expected to be as much as 265,000 mg/L. 

Current equipment development emphasizes 

adaptation of conventional petroleum-industry 

technology to higher temperatures and greater 

pressures, and testing of new materials and designs for cableheads and seals that will continue 

to function properly at extreme environmental 

conditions. A new logging cable with Teflon insulation and corrosion-resistant alloy armor is now 

being purchased by the U.S. Department of Ener51 

gy for testing at the Salton Sea site by the U.S. 

Geological Survey. 

Analysis of complex alteration patterns associated with geothermal regions requires sophisticated interpretation techniques and rlodifications in logging-tool configuration. Initial research 

focused on the application of standard ccmputeranalysis techniques such as cross-plotting of nuclear logs and histograms of log values to identify 

zones of alteration. Gamma spectral lo5s have 

been used at the Raft River, Idaho, and Roosevelt 

Hot Sprints, Utah, geothermal areas to further 

characterize the alteration minerals adjacent to 

boreholes. We are currently refming techniques 

for analysis of gamma spectral logs, and applying 

computerized statistical methods to . identifying 

alteration types anrl clay sequences. 

Most fluid production in geothermal reservoirs 

is associated with natural fractures. Fract;ure conduits may be important in the circulation of 

ground water through geothermal systems. Our 

research has emphasized the development of both 

fracture-characterization equipment capable of 

withstanding the geothermal environment, and 

new analytical techniques for fracture ch ~acterization. We devote a major part of our existing 

tool development effort to the acoustic borehole 

televiewer, which produces an ultrasonic image of 

the borehole wall. New fracture-characterization 

methods are based on the quantitative interpretation of acoustic attenuation using rece'1tly designed, low-frequency, acoustic loggin~~ equipment. These techniques have been verified at several nongeothermal sites on the Canadiar Shield, 

and will be further tested in the propose,i Salton 

Sea deep borehole. 

The requirement to relate the great ~tail inherent in geophysical logs with the large-scale information obtained from surface geophysical surveys is a critical part of geothermal exp10ration. 

An example of this approach is the correlation of 

borehole acoustic surveys with vertical seismic 

profiles (VSP). One preliminary study vras performed on a gabbroic batholith in eastern Massachusetts (fig. 1), and several additional studies 

are planned. 
4 

3 

(I) 

.... 

!2 

CD 

:E 

1 

0 

Compressional wave from surface 

Acoustic 

amplitude 

VSP data 

200-

E 

ci 

0 260- a:l 

-'-:J 

(I) 

!\ 

~ 280-

..2 \ CD 

.0 

r. 

... 

0. 

CD 

0 

300-

FIGURE I.-Comparison of acoustic waveform log amplitude attenuation with VSP tube wave generation for a large fracture 

set at nearly 300 m in depth in northeastern Massachusetts. 

52 
THERMAL MATURITY MAPPING OF 

THE UNITED STATES 

James G. Palacas 

The measured response of sedimentary organic 

matter to the combined effects of intensity and 

duration of heating in the Earth is commonly referred to as thermal maturity. The U.S. Geological Survey is compiling a set of maps showing 

thermal maturity of rocks in the sedimentary basins of the onshore conterminous United States. 

The maps will show three levels of maturity 

bounded by the 0.6 and 1.3 percent vitrinite reflectance equivalent (VRE) levels, which are generally believed to mark the start and end of significant oil generation. The set will consist of a surface map and maps showing depth contours to the 

0.6 and 1.3 VRE boundaries. Some of the areas 

for which preliminary compilation is complete are 

the greater Green River Basin, Denver Basin, 

Piceance Basin, northern Appalachian basin, and 

Williston basin. 

Comparisons of thermal maturity patterns with 

oil and gas occurrence in these basins show interesting relations. In the Denver Basin, for example, most oil is reservoired in thermally immature 

sedimentary rocks, implying long-distance migration from deeper parts of the basin. By contrast, 

in the Appalachian basin, the occurrence of oil and 

the transition from oil to gas follow closely the 

0.6 and 1.3 VRE maturity levels. This latter relation between thermal maturity and oil and gas occurrence fits the classical carbon ratio theory 

stated in 1915 by David White of the U.S. Geological Survey. 

Besides basin-wide mapping of thermal maturity, local detailed knowledge of maturity can contribute to understanding the structure and history 

of complex thrust belts by identifying anomalous 

superpositions of contrasting maturities and by 

showing whether generation of oil occurred when 

conditions were right to develop economic accumulations. 

Thermal maturity, a fundamental property of 

sedimentary rocks, has wide potential application 

beyond petroleum exploration and petroleum resource assessment. The importance of organic 

maturity has long been recognized by the coal industry. The economic value of coal deposits and 

the technology of coal utilization are directly re53 

lated to levels of organic maturation (rank). Some 

types of precious metal and rare element mineralization can be recognized from anomalous patterns 

of thermal maturity of potential hos~ rocks. 

Knowledge of regional thermal maturity may refine reconstructions of paleotectonic proce~ses and 

may improve our understanding of the thermal 

history and physical state of the lithosp'-lere beneath sedimentary basins. 

TRACE-ELEMENT ASSOCIATIONS IN c~-,ALS 

OF THE EASTERN UNITED STATE!' 

Curtis A. Palmer, Paul C. Lyons,. 

and Zoe Ann Brown 

Most of the trace elements in coal beds of the 

Eastern United States are associated with microscopic mineral species that are detrital, syngenetic, or epigenetic in origin. Vitrinite, th~ major 

maceral in these coals, may include Sllbmicroscopic mineral grains with specific elemerts which 

along with organically bound trace elements contribute to the inherent ash of the coals. By comparing the trace-element compositions of vitrinite 

concentrates with the compositions of tl'~ whole 

coal, one can interpret whether particular trace 

elements are vitrinite associated or whole-coal associated. 

Nine hand-picked vitrinite concentrates, from 

eight coal fields or basins in Eastern United 

States, were analyzed for 29 trace elements using 

instrumental neutron activation. These concentrates represent coal of various ranks from the 

following areas: one meta-anthracite f'"om the 

Narragansett Basin (Massachusetts), two anthracites from the folded Appalachians (Penn~ylvania, 

West Virginia), four high-volatile B to lovr-volatile 

bituminous coals from the Appalachian Plateaus 

(Alabama, West Virginia, Maryland) and two 

high-volatile C bituminous coals from the Illinois 

Basin (Indiana, Kentucky). The high-temoerature 

(1,000°C) ash contents of these concentrates were 

2 percent or less, except for the meta-anthracite, 

which was 5 percent. 

The distribution of rare-earth elements (REE) 

in the concentrates is distinctly different for the 

four rank groups (fig. 1). The REE distribution 

in the meta-anthracite concentrate has a Eu anom-
FIGURE !.-Representative rare-earth concentrations in the 

four different vitrinite rank groups (average shales from 

1966 study by Haskin and others). 

aly and is enriched in La. This anomaly may be 

due to microscopic impurities in the concentrate. 

The anthracites and the high-volatile C bituminous concentrates have similar distributions that 

are depleted in lighter REE but have markedly 

different La:Ce ratios. The depleted light REE 

distributions may reflect differences in geochemical processes or a different constituent diluting 

the clastic-shale pattern. The Appalachian 

bituminous concentrates have relatively flat REE 

patterns similar to the average shale pattern but 

slightly depleted in heavy REE. Whether or not 

these distributions are due to rank or regional differences is not clear. 

Significant correlations of Fe, As, and Sb for 

all concentrates indicate association in pyrite. 

Other significant correlations (such as K, Hf, Ta, 

Th, and the REE) suggest that clays and heavy 

accessory minerals such as phosphates, rutile, and 

zircon may be present. A comparison of trace elements in the whole coal with those in the vitrinite 

concentrates indicates that certain trace elements 

are associated with the organic matrix of the 

coals. 

THE SHUBLIK FORMATION-A MODEL 

FOR DEPOSITION IN 

AN ANCIENT MARINE UPWELLING ZONE 

Judith Totman Parrish 

The Shublik Formation (Triassic, North Slope 

of Alaska) comprises several lithologic facies that 

are consistent with deposition in an upwelling 

zone. These include the following: (1) black, laminated, pyritic limestone; (2) nodular and oolitic 

phosphorite; and (3) glauconitic sandstone and silt54 

stone. The facies are distributed h east-westtrending belts, with the limestone facies farthest 

to the south (basin ward) and the glau ~onitic facies 

farthest to the north (shoreward), where it occurs 

only in the subsurface. This distrib'ltion also is 

reflected in the vertical succession. Although the 

facies intertongue, the limestone and glauconite 

are never interbedded with each oth~r, but both 

can be interbedded with the phosphor~te. 

Rocks in the limestone facies contain as much 

as 6 percent total organic carbon. ':':'he high organic carbon content, paucity of bioturbation, 

presence of pyrite grains and nodules, and relative 

enrichment in such elements as co}'<:1lt, copper, 

and nickel all suggest that the rocks in this facies 

were deposited in an anoxic enviro~ment. Furthermore, the limestone facies is fossr~ferous, containing extremely abundant, very thin shells of 

pelagic bivalves. The abundance of tl'a.se shells is 

evidence for high biologic productjvity in the 

water column overlying the anoxic sediments. 

Phosphate in the adjacent facies (as much as 14 

percent P in the nodules) supports thi~ interpretation. Phosphate indicates a high rate of supply of 

phosphorus-rich organic matter to tl'a. sedimentwater interface; in modern upwelling zones, the 

phosphate is mobilized from the organic matter in 

the anoxic zone and reprecipitated fi: the zone's 

edges. Glauconite in the third facies is indicative 

of slightly reducing conditions. Glauconite occurs 

as filling in microfossil tests, glauconitized fecal 

pellets, grain coatings, and cement. The former 

two types of grains can result from min.ro-reducing 

environments, but the latter two types suggest 

a reducing environment in the sediment as a 

whole. Therefore, the lithological and geochemical 

facies of the Shublik Formation ar~ congruent 

with a depositional environment in which high 

biologic productivity created an oxygenation gradient from anoxic in the most highl;r productive 

part to slightly dysoxic closer to tb~ shoreline. 

This interpretation is most consistent with the 

conditions and sediments found in mcdern upwelling deposits. 

STRUCTURAL DEVELOPMENT o~ THE 

SOUTHEASTERN MARGIN 

OF THE ANADARKO BASIN, OKLI-"'OMA 

William J. Perry, Jr. 

Field investigations in the weste':"Il Arbuckle 

Mountains, on the southeastern mf.rgin of the 

Anadarko basin, Oklahoma, show trat compres-
sive deformation of Late Mississippian to Pennsylvanian age has played a dominant role in the 

structural development of the southeastern 

Anadarko basin, followed in Late Pennsylvanian 

(Virgilian) time by a modest amount of strike-slip. 

Both gravity sliding and strike-slip have recently 

been favored by others to fully explain the structural development of the area. My investigations 

do not support these hypotheses. 

Mesoscopic south-dipping contraction faults and 

north-vergent concentric folds with associated uplimb thrusts, exposed on the crest and southwestern limb of the Arbuckle anticline south of Turner 

Falls, Oklahoma, are cut by strike-slip faults associated with the left-lateral Washita Valley fault 

system. Along the main strand of the Washita 

Valley fault in the Turner Falls area, a pull-apart 

graben is filled by Upper Pennsylvanian Collings 

Ranch Conglomerate. This graben indicates that 

the strike-slip motion was transtensional and 

hence not responsible for compressional deformation. Consequently, the Arbuckle anticline does 

not represent a positive flower structure. The 

length of the graben appears to constrain the magnitude of strike-slip motion along the Washita Valley fault zone to less than 2 miles. Surface features of left-slip faults of the Washita Valley system and associated antithetic right-slip faults of 

small displacement indicate that these faults 

formed subsequent to the growth and erosion of 

the Arbuckle anticline to near-present erosional 

levels, which is consistent with the observed 

cross-cutting relationships. 

Early contraction faults and associated minor 

folds in the Ordovician Viola Limestone on the 

north limb of the Arbuckle anticline, Lake Classen 

area, have been passively rotated with the north 

limb and are not evidence of gravity sliding. Locally this limb is overturned and the early deformational features rotated more than 90°. 

Farther north, in the Sooner Quarry-SW Davis 

oil field area, the north-trending Russell fault system displays late right-slip motion superimposed 

on earlier compressional deformation features associated with the growth of the Russell anticline. 

More than 90 percent of slip lines observed in 

slicken-sides on the quarry walls indicate a major 

component of dip-slip motion. 

The mesoscopic deformational features observed 

require that northeast-southwest compression, 

rather than strike-slip, has played a dominant role 

in formation of the Arbuckle anticline and associated oil-producing structures, along a trend 

that projects westward into the Cement Field 

area in the deep Anadarko basin. My findings are 

consistent with the basement-involved thrust origin of the Arbuckle anticline proposed by W. G. 

Brown, Baylor University, as well as the more 

complex multistage deformational history proposed by K. C. Nielsen and Q. T. Islam, University of Texas at Dallas. My field data require that 

strike-slip faulting occurred late in the deformational history of the area, subsequent to the development of the Arbuckle anticline and associated southeastern margin of the Anadarko basin. 

BURIAL HISTORY AND TIMING OF 

THERMAL GAS GENERATION IN 

CRETACEOUS ROCKS, 

EASTERN UINTA BASIN, UTAH-EVIDENCE 

FROM LOPATIN RECONSTRUCTION 

Janet K. Pitman and Karen J. Franczyk 

Burial reconstruction profiles of Cretaceous and 

Tertiary sequences in the eastern Uinta Basin, 

Utah, reveal that major tectonic events, which 

took place during the Laramide and later periods 

of epeirogenic uplift and erosion associated with 

the development of the Colorado Plateau, controlled the thermal evolution and timing of hydrocarbon generation. Upper Cretaceous rocks in the 

eastern Uinta Basin contain large amounts of nonassociated thermogenic gas trapped in diagenetically modified, low-permeability reservoir sequences. These units are of the same age and origin as other hydrocarbon-bearing rocks that are 

currently being explored in the Rocky Mountain 

region; however, little is known about their source 

potential or generation history. This study applies 

the Lopatin method to (1) reconstruct the burial 

history of Cretaceous rocks in the eastern Uinta 

Basin, (2) evaluate the thermal gradient as a function of time, (3) determine the effect of episodic 

uplift and erosion on maturation, and (4) establish 

the time at which gas generation commenced in 

these rocks. 

Studies along the outcrop document that prolonged sedimentation occurred during Late Cretaceous in marine and nonmarine settings along the 

margin of the Western Interior Cretaceous seaway. In the late Campanian to early Maestrichtian, a regional unconformity that now separates 

Cretaceous and Tertiary strata across much of the 

basin developed, as widespread differential ero55 
View northward up the Sheridan Glacier from tidewater, Prince William terrane, near Cordova, Alaska. Present TACT seismicrefraction lines extend north from approximately this point some 330 km inland to near the Denali fault in central Alaska. 

A number of strike lines also have been shot. This location marks southern end of land-based TACT work, but future 

plans call for seaward extension south into Prince William Sound. Original color slide by D. L. Campbell, August 1985. 

sion associated with Laramide tectonism occurred. 

The amount of section eroded during the Late 

Cretaceous did not affect the thermal maturity of 

the remaining Cretaceous rocks because these 

units were never deeply buried. We have constructed a preliminary burial history model which 

demonstrates that Cretaceous rocks were thermally immature until the middle Oligocene, when 

they reached their maximum depth of burial, following the deposition of approximately 7,000 ft of 

Tertiary sediments. The duration of maximum burial for these Cretaceous rocks (from about 32 to 

about 17 Ma) was relatively brief, probably less 

than 15 m.y.; however, during this period thermal 

generation of gas began and the present level of 

maturation was attained. Our burial history model 

indicates that sedimentary burial rather than variations in the temperature regime controlled the 

56 

thermal maturation of organic matter. The 

paleogeothermal gradient, estimated at about 

1.8°F/100 ft, appears to have been fairly constant 

from Late Cretaceous through middle Miocene 

time. Beginning in the Miocene and continuing 

possibly into the present, the Colorado Plateau 

along with the Uinta Basin was episodically uplifted and intensely eroded. Widespread unroofing 

of Tertiary strata through much of the eastern 

and central part of the basin caused a gradual decrease in the paleogeothermal gradient to the 

cooler present-day gradient, estimated at about 

1.6°F/100 ft. In response to these lower temperatures, the rate of thermal gas generation decreased. 

The evolution of the pressure regime in the 

eastern Uinta Basin may be related to its maturation-generation history. Several studies have at-
tributed high formation pressures in low-permeability rocks to the generation of hydrocarbons 

from interbedded carbonaceous source rocks. Indirect pressure data from wells recently drilled in 

the eastern part of the basin indicate that Cretaceous rocks, presently at burial depths of about 

9,000 ft, are slightly overpressured. Thus, it is 

probable that abnormally high pressures may 

have been widespread in younger Cretaceous 

rocks when they were at their maximum depth 

of burial and undergoing peak gas generation. 

These high formation pressures may have gradually dissipated to normal or subnormal pressures 

in response to lowered temperatures caused by regional uplift and erosion during the late Tertiary. 

USGS MULTICHANNEL SEISMIC-REFLECTION 

PROFILE 25-A STRATIGRAPHIC 

REFERENCE SECTION FOR THE 

BALTIMORE CANYON TROUGH 

C. Wylie Poag and John A. Grow 

U.S. Geological Survey multichannel seismic-reflection profile 25, which crosses the depocenter 

of the Baltimore Canyon trough perpendicular to 

the New Jersey shoreline, serves as the standard 

stratigraphic reference section for the trough and 

the contiguous wedge of deep-sea deposits along 

its eastern margin. Seismostratigraphic interpretations of line 25 and a closely spaced grid of intersecting seismic lines are integrated with lithostratigraphic and biostratigraphic analyses of 50 

boreholes to interpret the geologic history of this 

East Coast region. 

Our interpretation of line 25 indicates that more 

than 20 km of sedimentary strata fills the depocenter of the trough. At the base of this sedimentary column is 5 km of inferred Late Triassic synrift sediments, presumed to comprise chiefly continental deposits, including volcanogenic beds. A 

major erosional unconformity separates the synrift 

deposits from overlying postrift sequences. The 

oldest postrift section consists of 12 km of Jurassic 

rocks, which range from nonmarine(?) facies near 

shore to shallow-water carbonate facies along the 

outer shelf and deepwater carbonates on the Jurassic slope and rise. Evaporitic strata are present 

as ridges and diapirs within the shelf deposits. An 

Oxfordian shelf-edge reefal bank is a notable feature and a potential target for petroleum exploration within this Jurassic carbonate regime. 

57 

During the Early Cretaceous, sedimentation 

and subsidence rates diminished; siliciclas~ic debris buried the shelf-edge reefal bank and terminated widespread carbonate deposition on the 

shelf, while supplying large quantities of terrigenous detritus to abyssal fans and "black-shale" 

facies as far as 400 km from the shelf edge. Siliciclastic deposition dominated the remainder c f Mesozoic time as rising Late Cretaceous sea levels 

established marine environments west of the present-day outcrop of Cretaceous strata in New J ersey. 

A dominantly carbonate regime was reir~tated 

during the Paleogene, as deepwater biosiliceous 

chalks, limestones, and calcareous clays accumulated throughout the trough and along its eastern 

margin. The dominance of carbonate dep<:lsition 

was terminated, however, in the Oligocene, when 

terrigenous marine sequences again fillfld the 

trough. Subsequently, an unusually large delta 

complex prograded across the shelf in th?. Miocene, initiating development of what is now the 

New Jersey continental slope. Since then, chiefly 

noncarbonate deposition has characterized the 

trough. 

Paleobathymetric cycles and regional un~onformities within this trough can be traced from the 

coastal plain to the upper rise, indicating that sealevel fluctuation in concert with basin subridence 

played a major role in determining the depositional fabric of the trough and its seaward margin. 

Depositional sequences on the shelf have equivalents on the slope and rise, and correspc nd remarkably well with supercycles of the controversial Vail depositional model. 

Postrift tectonic movement has been chiefly 

long term subsidence brought about by lithospheric cooling and sediment loading. Ther~ processes produced several large growth faults and 

an elongate, faulted anticlinal structure, which 

form potential petroleum traps along the eastern 

edge of the trough. 

PETROLEUM GENERATION AND MIGRATiflN IN 

LOWER JURASSIC LACUSTRINE SEQUEN~ES, 

HARTFORD BASIN, CONNECTICUT AND MAS· 

SACHUSEnS 

Lisa M. Pratt, April K. Vuletich, and Robert C. 

Burruss 

The Hartford basin in Connecticut and Massachusetts is one of a series of elongate fault-
bounded basins along the eastern margin of North 

America that contain Triassic and Jurassic sedimentary rocks. Nonmarine deposits and basalt 

flows in the Hartford basin total about 4 km in 

thickness, and some units can be correlated for 

140 km along the length of the basin. Deep-water 

lacustrine sequences typified by lithologic cycles 

of (1) gray silty mudstone, (2) black laminated 

shale, and (3) gray silty mudstone are well developed in the Lower Jurassic Shuttle Meadow 

and East Berlin Formations. Crossbedded channel 

sandstones, red flood-plain mudstones, and ripplemarked lacustrine siltstones were deposited during dry periods between times of development of 

extensive perennial lakes. 

In order to evaluate the thermal history and petroleum potential of the Hartford basin, outcrop 

samples were collected from localities spanning 

the north-south extent of the basin. Organic-carbon content, Rock-Eval pyrolysis yield, and carbon isotope ratio of organic matter were determined for 66 samples of medium-gray to black 

shale and siltstone. Amount and character of extractable organic matter were determined for ten 

representative shale samples, one "solid" bitumen 

intermingled with calcite spar from a joint in the 

Lower Jurassic Holyoke Basalt, and one "sticky" 

bitumen from the core of a cylindrical concretion 

in the East Berlin Formation. 

Temperatures of maximum pyrolytic yield 

(T max) and hydrogen indices (HI) of the black 

lacustrine shales (organic-carbon content = 0.9 to 

3.8 weight percent) indicate sharply decreasing 

thermal maturity from north to south in the 

Hartford basin. T max values are greater than 

450°C and HI values are less than 50 mg/g in Massachusetts and northern Connecticut. Correlative 

shales in central and southern Connecticut generally have T max values between 425° and 436° and 

HI values between 150 and 280 mg/g. Scattered 

localities in Connecticut have anomalously high 

thermal indices, but most localities are marginally 

mature to mature with respect to petroleum generation. 

Extraction yields are 1,800 to 3,100 ppm for the 

black lacustrine shales. The n-alkanes have a 

smooth distribution with a maximum between nC17 and n-C19. Pristane/phytane ratios are about 

1.6. The distribution of n-alkanes and biomarkers 

in the extractable portion of the "solid" bitumen 

from the Holyoke Basalt is indistinguishable from 

that of the shale extracts. The extractable portion 

58 

of the "sticky" bitumen contains n-alkanes with 

slight even-carbon predominance from n-C18 tonC24, but the distribution of biomarkers is similar 

to that of the shale extracts. Two-phase, liquid 

and vapor fluid inclusions in cements adjacent to 

both types of bitumen contain brightly fluorescent 

hydrocarbons. 

Organic geochemical analyses of surface samples 

indicate that the Shuttle Meadow ani East Berlin 

Formations are moderate to good oil source rocks 

in the central and southern portions of the 

Hartford basin. These same rocks in the northern 

portion of the Hartford basin are overmature with 

respect to oil generation and occurr~'lce, but may 

be source rocks for gas. The cumulative thickness 

(8-10 m) of widespread possible source rocks 

should be adequate for commercial petroleum accumulation. Extensive faulting and the large area 

of contact between potential source t~ds and adjacent siltstones and sandstones may have enabled 

efficient expulsion and migration of l'ydrocarbons. 

The presence of hydrocarbon liquids in fluid inclusions demonstrates at least local generation and 

migration of petroleum in the Hartford basin. 

MAGNETIC MINERALS AND HY""ROCARBON 

SEEPAGE-POSSIBILITIES r·.,R 

MAGNETIC DETECTION OF OIL FIELDS 

Richard L. Reynolds, NeilS. Fishman, 

Mark R. Hudson, J. A. Karaclr~wski, 

and Martin B. Goldhabf.'"' 

Aeromagnetic anomalies detected over some oil 

fields in the Anadarko basin (Oklal''lma) and on 

the North Slope (Alaska) have been attributed to 

near-surface diagenetic magnetite fiJrmed in the 

presence of migrated hydrocarbons. If magnetite 

or other magnetic minerals result fr1m hydrocarbon seepage, aeromagnetic techniques offer a 

promising complement to conventional exploration 

methods. Rock magnetic, paleom~.gnetic, and 

geochemical studies have been under~aken to test 

models of magnetite diagenesis related to hydrocarbon seepage and to investigate the sources of 

magnetic anomalies over the Cerr.ent oil field 

(Anadarko basin, Oklahoma), the Simpson oil field 

(North Slope, Alaska), and the Wyoming-IdahoU tab thrust belt. 

Magnetite, reported previously in well cuttings 

from the Cement field, commonly exhibits synthetic textures and contains inclusior~ of industri-
al iron. The magnetite, thus, is a contaminant that 

probably was introduced during drilling. Ferrimagnetic pyrrhotite (Fe7S8), however, occurs at 

shallow depths ( =70 to 300 m) above oil-producing 

strata, and it may contribute to aeromagnetic 

anomalies over the Cement field. The limited areal 

distribution of the pyrrhotite and the closely similar sulfur isotopic compositions of the pyrrhotite 

(-2.0 to + 9.9 per mil) and of underlying crude 

oils ( + 1.8 to + 7.3 per mil) suggest that pyrrhotite formed from aqueous sulfide in hydrocarbonbearing brines that migrated toward the surface 

along numerous faults in the area. 

At the Simpson oil field, greigite (Fe3S4), 

another authigenic ferrimagnetic iron sulfide mineral, is conrentrated locally in Upper Cretaceous 

mudstone and sandstone. Highest values of magnetic susceptibility and intensity of natural remanent magnetization (NRM) in unoriented core 

samples correspond to zones of greigite enrichment. Greigite thus may be the dominant source 

of magnetic anomalies over the field, but some 

contribution from detrital iron-titanium oxide minerals, principally titanohematite, is possible. The 

greigite formed via processes involving sulfate-reduction by bacteria that used either detrital organic matter or migrated hydrocarbons as a food 

source. 

In the Wyoming-Idaho-Utah thrust belt, the Jurassic Preuss Formation has magnetizations as 

much as 0. 76 amperes/meter (average 0.14 Aim) 

west of the Absaroka thrust fault, where 

aeromagnetic anomalies locally correspond to exposures of the Preuss, and much lower magnetizations (average 0.44 x 10-2 A/m) east of the Absaroka fault. The magnetization is carried by large 

(10 to 80 f.Lm diameter), rounded, titanium-bearing 

detrital magnetite, commonly concentrated along 

heavy mineral laminations. Visible diagenetic 

magnetite has not been found, and the presence 

of submicroscopic diagenetic magnetite is very unlikely, on the basis of a linear relation between 

site-mean values of magnetic susceptibility and 

NRM intensity. Carbon isotopic compositions of 

calcite cement (-2.4 to + 1.5 per mil) do not indicate that hydrocarbons influenced the preservation of the detrital magnetite. 

Diagenetic magnetite is not the source of magnetic anomalies associated with the Cement and 

Simpson oil fields or with the Preuss Formation. 

At each area, instead, a different authigenic magnetic mineral has formed, or a detrital mineral has 

59 

been preserved, under vastly different g~ochemical conditions. A complete evaluation of 

aeromagnetic methods in locating hydroc~rbon deposits should include study of different g~ochemical and structural settings to disting''ish authigenic (or detrital) magnetic minerals fo"""lled (or 

preserved) under the influence of hydr1carbons 

from magnetic phases that are unrelated to seepage. 

NANUSHUK GROUP COAL INVESTIGAr~NSNORTH SLOPE OF ALASKA 

E. G. Sable, G. D. Stricker, and R. H. /'~olter 

The North Slope of Alaska contains vast resources of virtually undeveloped coal, much of 

which occurs within mineable depths. The main 

coal-bearing units, the Corwin and Chaniler Formations of the Lower and Upper Cretaceous 

Nanushuk Group, underlie more than 25,000 mi2 

(64, 750 km2) of the North Slope. Ther contain 

low-sulfur, low-ash, subbituminous, and cokingquality bituminous coal in gently dipping beds as 

thick as 20 ft (6.1 m), within stratigrapl,ic intervals as thick as 10,000 ft (3,050 m). Coal resources 

of lesser quality and quantity also occur in other 

Upper Cretaceous, Lower Mississippian, and Tertiary rocks. 

The river-dominated, in part coeval, Corwin 

and Umiat deltas controlled the distribution of 

Nanushuk Group coal-forming environments. The 

larger Corwin delta (Corwin Formation), in the 

western part of the North Slope, prograd~d northeastward and eastward; the smaller Umiat delta 

(Chandler Formation), in the central part, prograded northward. Most organic deposits formed 

on delta plains; others formed in alluvial-plain or 

delta-front environments. Most North Elope coal 

beds are lenticular and irregular, probably due to 

accumulation in interdistributary basinf, infilled 

bays, or inland flood basins. Some widespread 

tabular beds that formed on wide, slowl:T sinking 

delta lobes may also be present. The major controls of coal rank and degree of deformation were 

depth of burial and subsequent tectonism. 

Since 1975, ninety-six coal samples from the 

Corwin and Chandler Formations h2 ve been 

analyzed in order to evaluate coal quality and element distribution. Their apparent rank ranges 

from lignite A in undeformed strata to high-volatile A bituminous in moderately deforrr~d units. 
Coal from the North Slope is significantly lower 

in ash, volatile matter, 0, Si, AI, Ca, Fe, Ti, Cu, 

F, Li, Mn, Mo, Pb, Sb, Se, Th, and Zn than Cretaceous coal of the western conterminous United 

States. Sulfur values are as low as 0.1 percent, 

and elements that normally show a positive correlation with sulfur are also low. Variations in element content probably reflect geochemical differences in the Corwin and Umiat delta systems. 

Nanushuk Group hypothetical coal resources on 

the North Slope are estimated to be 3.1 trillion 

short tons. This value is the sum of 1.8 trillion 

tons of near-surface ( <500 ft (150 m) of overburden) bituminous coal, 1.24 trillion tons of near-surface subbituminous coal to lignite A, and 0.06 trillion tons of more deeply buried subbituminous 

coal. Of the total, roughly 2. 53 trillion tons of coal 

occurs in beds having less than 15° dip. These estimates indicate that the North Slope of Alaska may 

contain as much as one-third of the United States 

coal resources. 

Information about North Slope coal is scant 

compared to major coal-producing areas in the 

conterminous United States: the Powder River 

Basin, for example, contains more than 5,000 test 

wells, whereas North Slope coal information is 

available from less than 50 test wells. A systematic drilling program is needed to develop more accurate resource estimates and increase the currently sparse and mostly localized information on 

quality and geochemistry of North Slope coals. 

THE SAL TON SEA SCIENTIFIC 

DRILLING PROGRAM-A PROGRESS REPORT 

J. H. Sass, J. D. Hendricks, S. S. Priest, 

and L. C. Robison 

One of the first major experiments of the U.S. 

Continental Scientific Drilling Program is being 

carried out in the Imperial Valley of California, 

as the Salton Sea Scientific Drilling Program 

(SSSDP). The research well is situated near the 

southeast end of the Salton Sea in the Salton 

trough, a tectonic depression within the transition 

zone between the spreading centers of the Gulf 

of California and the San Andreas transform fault. 

The trough is a fluvial sedimentary basin with associated evaporitic and lacustrine deposits. Within 

it high temperatures (up to 370°C at only 2 km 

depth) and hypersaline brines (up to 250,000 ppm 

total dissolved solids) are encountered. The drill 

site is near the hottest part of the Salton Sea Geothermal Field as deduced from temperatures in 

60 

previously drilled deep wells and temperatures 

extrapolated from shallow (=50-100m) wells. The 

well is being drilled using standard technology, 

but it is different from conventional exploration 

or production wells in a number of ways, chief 

among which is the priority of sd:mtific over 

economic objectives. The primary goals are to 

study the processes involved in an Bctive, magmatically driven hydrothermal system. The temperatures, pressures, and salinities in the well 

provide an opportunity for the evaluation of geothermal energy potential and a converient laboratory for the study of greenschist me+.amorphism 

and hydrothermal ore formation in place. 

To facilitate the studies of these ac+ive processes, the SSSDP has attempted to maximize data 

collection in four areas: (1) core re~overy, (2) 

geophysical logs, (3) downhole experiments, and 

( 4) sampling of formation fluids. The extent of all 

these activities is limited by the hostile environment encountered in the research well. Some procedures routinely available in more benign regimes (such as open-hole packer test.s, in-place 

stress measurements, and gun-perforation) are 

not technologically feasible in the Salton Sea experiment. 

The science experiments fall into three major 

categories: downhole, surface, and off-';;ite. In the 

first category we shall attempt to obtai:"l a detailed 

equilibrium temperature profile by a time-series 

of continuous temperature logs during the postdrilling idle period. This profile will pr~1vide information vital to the interpretation of virtually all 

other data obtained from the well. Other downhole experiments include fluid samplin,5, temperature-pressure-flow measurements d·.uing flow 

tests, vertical seismic profiling, an1 borehole 

gravity and fracture studies using acoustic logging 

and borehole televiewers. Surface experiments 

are primarily thermodynamic measur:!ments and 

the collection of fluid samples during flow tests. 

Off-site experiments deal with description, analysis, and measurement of fluid and core samples 

obtained during drilling. The major subdivisions 

within this latter group include the c'lemistry of 

liquids and gases and the petrology, geochemistry, and physical properties of core samples. 

At the conclusion of the post-drilPng shut-in 

phase (about 6 months duration) a number of options will arise for further work. If flmv tests during and immediately after drilling are encouraging, support will be sought for studies aimed at 

a systematic reservoir evaluation. The leaseholder 

(Kennecott) may opt to take over the well as a 
commercial venture. If neither of these options is 

exercised, the well will be plugged and abandoned 

at th~ conclusion of the shut-in period. 

The new data from SSSDP should result in refined models for the Salton Sea system, improve 

assessment of its geothermal energy potential, 

and provide important constraints on models of 

metamorphism and ore formation. The project 

should also fulfill scientific and organizational 

goals by providing guidelines for future continental scientific drilling experiments. 

CLASSIFICATION OF CLASTIC RESERVOIRS 

FOR ENHANCED OIL RECOVERY 

C. J. Schenk, J. W. Schmoker, and D. L. Gautier 

Enhanced oil recovery (EOR) encompasses a 

number of processes to chemically or thermally 

stimulate petroleum reservoirs to produce a portion of the oil remaining after primary and secondary recovery. Several hundred reservoirs in the 

United States are amenable to EOR processes. 

The purpose of this study is to assign reservoirs 

to generic classes, or populations, in order to determine which reservoirs should have precedence 

for EOR, and to provide a geologic data base that 

will aid selection of EOR processes. 

Reservoirs in clastic rocks can be described and 

classified in terms of facies, each of which has a 

set of primary sedimentologic, mineralogic, and 

petrophysical attributes. Potential EOR reservoirs will be grouped into populations based on 

similarity of facies. Each facies may include, or 

be separated by, impermeable mudstone layers 

that persist through burial, and which probably 

represent the most important control on fluid flow 

through a reservoir. The identification of these 

permeability barriers, and descriptions of their 

lateral extent and distribution, will be an important aspect in defining classes of reservoirs. 

The primary textures, mineralogies, and petrophysical parameters in each facies typically undergo diagenetic changes during burial that can 

significantly affect fluid flow in the reservoir. 

Changes in these reservoir properties during burial are a complex function of the primary mineralogy of a sandstone, the composition of any fluids 

that have passed through a sandstone, and the 

time-temperature exposure of the reservoir. The 

changes in reservoir properties among sandstones 

of similar primary mineralogies depend exponen61 

tially on temperature, and linearly on time, and 

may be systematized and predicted in terms of 

the reservoir time-temperature exposure. The 

time-temperature index of thermal maturity (TTl) 

is used as one convenient measure of time-temperature exposure. 

Using the populations of reservoirs as a starting 

point, the effects of burial processes upon reservoir properties will be the basis· for defining subpopulations based on other characteristics, such as 

fractures, authigenic mineralization, or hydrocarbon type. Identification of sub-populations based 

on these and other characteristics may be useful 

in decisions regarding the choice of EOR procedure. 

WINDOWS IN THE PULASKI THRUST SHEET 

AND THEIR IMPLICATIONS FOR HYDROCARBON 

POTENTIAL ALONG THE EASTERN PART OF 

THE APPALACHIAN OVERTHRUST PROVINCE 

Arthur P. Schultz and Donald E. Anders 

Highly deformed Cambrian through Devonian 

rocks are exposed in windows in the Pulaski 

thrust sheet of the Virginia Valley and Ridge 

structural province near the southern-central Appalachian junction zone. Detailed mapping of these 

exposures shows a consistency of structural style, 

namely, faulted and stacked antiforms with duplex 

geometry and folded roof thrusts. Strain intensity 

and the style of regional folds and faults suggest 

that the windows are shurflingsfensters which expose rootless, tectonic slices, or horses. Structural 

analyses of these rocks show that in thick-bedded 

carbonates and sandstones, cataclasis was the dominant deformation. By contrast, thin-bedded 

shales, sandstones, and limestones were isoclinally 

folded, cleaved, and boudinaged. Tectonic thinning 

and strain intensity in the horses are dependent 

on the distance of transport from their root zone, 

which may be a ramp in the trailing part of the 

subjacent Saltville thrust sheet. A 1982 interpretation by Leonard Harris and others of the U.S 

Geological Survey's central Virginia seismic line 

places this ramp east of and below the crystalline 

rocks of the Blue Ridge province. Geometric modeling of rocks in the windows supports this interpretation and suggests the existence of possible 

Cambrian through Mississippian hydrocarbonbearing rocks below the Blue Ridge thrust sheet. 
View northward from near head of Schwan Glacier on south flank of Cordova Peak, Chugach terrane, Alaska. For TACT 

seismic-refraction study, seismometers were deployed by helicopter at approximately 1-km spacing along a due-north line 

that extends up left side of glacier. Original color slide by D. L. Campbell, August 1985. 

Rock samples from the horses were collected to 

determine thermal maturity and source-rock potential. Preliminary results indicate that Devonian 

and Ordovician black shales in the windows could 

have been source rocks but that their present overmature condition probably indicates a low hydrocarbon potential for Paleozoic rocks below the 

eastern part of the Blue Ridge province. However, if the rootless slices overlie Paleozoic rocks 

of more western affinities, the maturation level 

in the slices is not indicative of the maturation 

levels in the overridden rocks. Consequently the 

hydrocarbon potential of rocks below the Pulaski 

and subsidiary Max Meadows thrust sheets and 

below the western part of the Blue Ridge province 

has yet to be determined. 

62 

LOW-ASH SYNTHETIC FUEL FROM 

LIGNITE, PEAT, OR SEWAGE SLUDGE 

Frank E. Senftle and Priscilla I. Hackney6 

The United States has large tonnages of lignite 

and peat that are considered unsuitable for fuel 

application. Concurrently, municipal governments 

in many areas of the world are facing an ever-increasing problem of the disposal of sewage 

sludge-a high-ash renewable carbon source. If 

the organic part of these carbon sources could be 

put into aqueous solution and reconstituted as a 

low-ash solid, a product might be obtained which 

6Graduate Student, Howard University, Washington, D.C. 20059. 
' 

~ '?" ., .. ·- ... \ •_,; 

' , ... .. ,.. \~ 

<.1 . 4l 

.. • ... ... . .. 

I 

~ • .. " .. 

• 

.... ' lcm • 

FIGURE !.-Photograph of polymer produced from sewage sludge. Typical values: Heating value 28 MJ/kg (megajoules per 

kilogram) (1.2 x 104 Btullb), sulfur =2 percent, and ash ,;:;4 percent. 

would be suitable as a fuel or a source material 

for producing organic chemicals. 

Petroleum chemists have long known that 

aliphatic and certain aromatic compounds form esters when reacted with concentrated H2S04• In 

63 

the presence of isoparaffinic compounds, these esters react further to form a polymer and sulfuric 

acid. The acid therefore functions as a catalyst. 

Similar chemical procedures can be used with 

peat, lignite, and sewage sludge to extract the or-
ganic fraction. The extracted organic fraction 

after polymerization could be separated as a solid 

fuel. 

Preliminary experiments have been made on 

peat, lignite, and sewage sludge. A photograph 

of a solid polymer formed from sewage sludge is 

shown in figure 1, and typical values of sulfur, 

ash, and heating value are given in the caption. 

GEOTHERMAL SYSTEMS IN THE 

CASCADE RANGE 

Michael L. Sorey, Steven E. lngebritsen, 

and Robert H. Mariner 

The Cascade Range is a 1,200-km-long belt of 

Quaternary volcanic terrane punctuated by several stratovolcanoes; it represents the only subduction-related volcanic arc in the conterminous 

United States. Magmatic heat sources within this 

range that could drive high-temperature geothermal systems are indicated by concentrations of 

Holocene silicic volcanic rocks at six eruptive centers and by regions of high regional heat flow that 

underlie most of the Cascade Range in Oregon. 

High-temperature geothermal systems have been 

identified at Meager Mountain (British Columbia), 

Newberry Volcano (Oregon), and Lassen Volcanic 

National Park (California), and exploration for 

similar systems is currently in progress by private 

industry at Medicine Lake Volcano (California) 

and Crater Lake (Oregon). 

Three general types of geothermal systems can 

be delineated within the Cascade Range-summit 

crater systems, caldera systems, and regional flow 

systems. Summit-crater systems occur at Mount 

Shasta, Mount Hood, and several other of the 

andesite-dacite composite volcanoes that display 

persistent fumaroles or hot springs. Although gas 

geothermometry yields estimates of subsurface 

temperature in excess of 200°C at Mount Shasta 

and Mount Hood, hydrothermal circulation in 

these systems appears to be confined to shallow 

depths within the summit craters and to downdip 

flow of heated ground water or steam condensate 

to warm springs along the flanks of the volcanoes. 

Caldera geothermal systems at Newberry, 

Medicine Lake, and Crater Lake appear to include 

zones of relatively deep fluid circulation along ring 

fractures. Test drilling by the U.S. Geological 

Survey at Newberry has provided evidence that 

permeable strata containing water at tempera64 

tures near 265°C exist within the volcanic section 

at depths of 1-2 km. Although these caldera systems may offer the greatest likelihood of hightemperature geothermal resources within the Cascade Range, geothermal exploration at Crater 

Lake and Newberry is currently restricted to regions surrounding the calderas. 

A regional flow system occurs at Lassen Volcanic National Park and in the Known Geothermal 

Resource Area to the south. It includes a central 

vapor-dominated zone at temperatures near 240°C 

that feeds steam to superheated fumaroles within 

the park. Hot water that upwells beneath this 

zone boils, and the liquid fraction flows laterally 

away from the park, eventually to discharge in 

hot springs at lower elevations some 10-15 km 

away. Exploration for geothermal resources at 

Lassen is focused on these zones of lateral outflow 

south of the park. 

Geothermal systems associated with hot springs 

located along the High Cascade-Western Cascade 

boundary in Oregon also may be regional in scale. 

Heat flow measurements, stable isotope relationships, geothermometer calculations, and results 

from a 2.5-km-deep drill hole fit a conceptual 

model involving circulation of meteoric water 

westward from the High Cascade axis at depths 

of 3 km and temperatures of 150°-180°C, and upflow along the edge of the graben within which 

the High Cascade volcanic rocks have been 

emplaced. The amounts of chloride contributed by 

the hot springs to nearby streams require discharge rates for individual systems that range 

from 1.1 to 110 L/s. Heat required to raise the 

temperature of this water to 150° -180°C could 

come from the regional heat flow (100 mW/m2 

(milliwatts per square meter)) for all but one of 

the spring systems. Additional heating might be 

related to shallow magmatic sources beneath the 

High Cascade axis. 

THE FORMATION AND ALTERATION OF 

TABULAR-TYPE URANIUM-VANADIUM 

DEPOSITS AS A VARIANT OF 

NORMAL DIAGENETIC PROCESSES 

IN ORGANIC-RICH SEDIMENTS 

Charles S. Spirakis and Paula L. Hansley 

Tabular-type uranium-vanadium deposits in the 

Grants uranium region of New Mexico, the Uravan mineral belt of Colorado and Utah, and the 
Henry Mountains mineral belt of Utah occur in 

fluvial sandstones of the Morrison Formation 

(Upper Jurassic) and exhibit similar geometry, 

mineralogy, and alteration. They differ strikingly, 

however, in the dominance of epigenetically introduced, pore-filling organic matter in the Grants 

ores in contrast to pore-filling authigenic chlorite 

in the U ravan and Henry Mountains deposits. Remnant traces of introduced organic matter, the 

fact that organic matter must be present to reduce 

uranium, sulfur and other elements in the ores, 

and uniquely etched garnets in ore-bearing horizons are evidence of previously greater abundances of introduced organic matter in the Henry 

Mountains and U ra van deposits. In the Henry 

Mountains, the association of 13C-enriched dolomite with the ores (described by H. R. Northrop 

in a 1982 study) and the destruction of detrital 

iron-titanium oxides in and around the ore zones 

provide additional evidence that greater amounts 

of organic matter previously existed than are now 

present. In the Grants region, gradations from organic-rich to chlorite- and coffinite-rich deposits 

and inclusions of carbon in coffinite indicate that 

chlorite and coffinite replaced introduced organic 

matter. We propose that this replacement proceeded further in the Henry Mountains and U ravan areas than in most of the Grants region and 

that the deposits have a similar genesis. Thus it 

is appropriate to combine information from these 

three areas to form a genetic model. 

Shortly after sedimentation, organic acid-bearing solutions migrated through the sandstones, altered detrital iron-titanium oxides, transported 

trivalent vanadium liberated from the irontitanium oxides, and finally deposited organic matter as tabular bodies in the host sandstones (processes from a 1985 study by C. E. Turner-Peterson and N. S. Fishman). As is typical of early 

diagenesis, bacteria catalyzed sulfate reduction by 

organic matter to produce pyrite. Concomitant 

with sulfate reduction was the precipitation of reduced uranium minerals and of ore-stage chlorite. 

Upon the exhaustion of sulfate in the sediments, 

fermentation of organic matter (also typical of 

early diagenesis) dominated the diagenetic chemistry. Because dolomite, especially 13C-enriched dolomite, is characteristic of the fermentation stage 

of diagenesis, and because sulfate in the ore stage 

inhibits the precipitation of dolomite, dolomite associated with the Henry Mountains deposits is 

concluded to represent the fermentation stage of 

65 

diagenesis; ankerite in the Grants region also 

formed after sulfate reduction and may be 

paragenetically equivalent to dolomite in the 

Henry Mountains area. Dolomite contjnued to 

form until the thermal limit of bacteria was 

reached (about 75°C or perhaps lower du?. to possible toxic effects of the ore elements on l'c::tcteria). 

Then, in the ensuing absence of bacteria that 

metabolize organic acids, organic acids derived 

from the maturation of organic matter be~ame important components of the solutions that produced 

the etching of garnets throughout the Henry 

Mountains and Uravan areas and in pa~s of the 

Grants region. The coincidence in space of the garnet etching with the replacement of organics by 

late-stage chlorite and coffinite indicateE that all 

these alterations are related to the maturation of 

organic matter associated with the ores. 

GEOCHEMICAL CHARACTERIZATION OF 

SELECTED COALS FROM THE 

BELUGA ENERGY RESOURCE AREr. 

SOUTH-CENTRAL ALASKA: 

SITE OF A PROPOSED COAL MINE 

Gary D. Stricker, Ronald H. Affolt~.-, 

and Michael E. Brownfield 

The Tertiary Kenai Group of the upper Cook 

Inlet region, south-central Alaska, is a nonmarine 

sedimentary sequence, as thick as 8,000 m. It consists, in ascending order, of the Hemlock Conglomerate, Tyonek Formation, Beluga Fe rmation, 

and Sterling Formation. All the units are coal 

bearing, but the thickest beds are foun'i in the 

Tyonek Formation of early Oligocene t0 middle 

Miocene age. This formation is a 1,160- to 2, 750-

m-thick sequence of massive sandstores, siltstones, and claystones with interbeds of thick coal 

and a minor number of tuffs(?) and tonsteins. The 

Tyonek Formation is believed to have accumulated in poorly drained alluvial lowlands adjacent 

to tectonically active highlands containing sporadically active volcanoes. 

The Beluga energy resource area is approximately 90 km west of Anchorage in tl'?. upper 

Cook Inlet region. This area contains over 1 billion 

short tons of coal resources in the Tyonel- Formation alone. The area is tentatively scheduled for 

coal production beginning in the early 1990's. For 

baseline data 43 samples representing e~qht coal 

beds (Capps, Waterfall, M, 0, Q, and three un-
named beds), were analyzed from four U.S. 

Geological Survey drill holes. Statistical summaries of proximate and ultimate analyses, heatof-combustion, forms-of-sulfur, and 40 major, 

minor, and trace elements were compiled and 

evaluated, along with the mineralogy of the lowtemperature ash for each sample. Analyses show 

an apparent coal rank that ranges from subbituminous B to subbituminous C, with a variable 

ash content of 4. 7 to 46.5 percent. Total sulfur 

ranges from 0.08 to 0.33 percent, one of the lowest reported total sulfur ranges for any United 

States coal. 

Concentrations of Si, AI, K, Ti, Be, Cr, Cu, F, 

Ga, La, Li, Sc, Th, U, V, Y, Yb, and Zr show 

a variation in concentration that is directly related 

to the ash content of the coal; linear correlation 

coefficients are greater than 0.8. The M bed has 

the lowest ash content as well as the lowest concentration of ash correlated elements, whereas the 

Capps coal bed has a relatively higher ash content 

and therefore, a higher concentration of these elements. The variability of ash content is probably 

a direct result of the proximity of the original peat 

swamp to nearby tectonically active highlands and 

the episodic nature and varying composition of the 

adjacent highland's volcanic eruptions. 

Mineral analysis of the low-temperature ash reveals a predominance of kaolinite with minor micatype clays and a varying amount of quartz. X-ray 

diffraction of selected coal samples indicates the 

presence of the hydrated alumino-phosphate mineral goyazite (SrA13(P04)(0H5)·H20), which is the 

strontium end member of the solid-solution plumbogummite series. The presence of this mineral 

is further supported by chemical analyses of the 

whole coal, which indicate unusually high concentrations of strontium (1,430 ppm) and phosphorus 

(4,100 ppm). Previous studies of the minerals of 

the plumbogummite series report the minerals occurring in altered nonmarine tuffs, which suggests 

that goyazite in the Tyonek Formation coals probably formed during early diagenesis of air-fall volcanic ash that landed in the peat accumulating 

swamps. 

RESERVOIR FLUIDS OF THE BACA, 

NEW MEXICO, GEOTHERMAL FIELD 

A. H. Truesdell and C. J. Janik 

At the Baca geothermal field in the Valles caldera, New Mexico, 19 deep wells were drilled in 

66 

Looking Northeast 

Weak upflow with 

conductive cooling 

+ 

335°C Hot water 

EXPLANATION 

Well with fluid entry point 

Redondo Pk 

/he 

/cold water 

0 1000 m 

L------·J 

Botto, of 2-phase 

zore 

Major fault 

Isotherm 

~ Fluidflow 

~ Heatflow 

FIGURE 1.-Cross section of the Baca geothermal field (view 

to northeast) showing deep 335°C upflow mixing with cold 

water to feed well ~ and cooling conductively to feed well 

B-15. No vertical exaggeration. 

an attempt to develop a 50-MW power plant. The 

chemical and isotopic compositions of steam and 

water samples from wells of the Baca field have 

been used to indicate uniquely the or~gin of reservoir fluids and natural reservoir processes. Two 

distinct reservoir fluids exist at Baca. These fluids 

originate from the same deep, high-temperature 

(335°C), saline (2,500 mg/kg Cl) parent water, but 

have had different histories during upflow (fig. 1). 

One fluid (from wells on the east. side of the 

field) is isotopically light, high in rad: 'lgenic noble 

gases, C02 and HC03, and low in Ca. It has a 

temperature of 290°-295°C and a reservoir 

chloride near 1,900 mg/kg. This f1'.1id resulted 

from rapid upward flow through the 1.1-1.4-m.y.-

old Bandelier Tuff reservoir rocks, af:.er long residence in pre-Bandelier (>7 m.y.) sediments and 

Precambrian basement rocks, and 25 percent dilution with high-altitude cold ground water from 

Redondo Peak (fig. 1). The other water (from the 

western wells) moved slowly through the Bandelier Tuff and cooled conductively (with minor 

steam loss) from 335°C to 280°-260°C. Apparently, 

short residence in old basement rockf has left this 
water with low radiogenic gases. Conductive cooling without mixing has kept the original chloride 

and relatively heavy isotope composition of the 

deep water. The recharge to the deep parent 

water is not well understood but may be from 

lower elevation precipitation outside the Valles 

caldera area. Pressures of 0 2 and S2 are controlled 

by mineral assemblages within the Bandelier Tuff. 

Gases are in equilibrium in all-liquid reservoir 

fluid at near reservoir temperatures and the concentrations of atmospheric gases are similar to 

those of air-saturated water, indicating little boiling and steam loss. 

All water, solutes, and gases in the reservoir 

fluids originate from air-saturated meteoric recharge water, water-mineral reactions, and rock 

leaching, with the possible exception of excess 

3

He that must have an ultimate mantle source. 

This gas could originate directly from magma or 

from deep leaching of intrusive volcanic rocks beneath the Bandelier. 

Chemistry of the Baca well fluids shows that 

natural reservoir processes are dominated in the 

west by slow upward fluid movement and conductive cooling, and in the east by rapid upflow and 

mixing with cold water. The two parts of the reservoir are poorly connected. These processes 

suggest that under exploitation, western wells 

will have low permeability and will be poor producers, and eastern wells may show cold water 

ingress. Neither condition is favorable for longterm electrical production. 

URANIUM ORE GENESIS IN THE 

CONTEXT OF BASIN EVOLUTION, 

SAN JUAN BASIN, NEW MEXICO 

Christine E. Turner-Peterson and 

Neil S. Fishman 

A basin analysis approach was used to understand uranium mineralization in the fluvial-lacustrine Jurassic Morrison Formation, San Juan 

Basin, New Mexico. Although distribution of uranium ore is areally and stratigraphically restricted, it was necessary, in order to develop a 

model for ore genesis, to understand the depositional setting of the entire Morrison Formation 

and to determine the role of depositional setting 

on hydrology and diagenesis. As a result, we not 

only understand uranium ore genesis in the San 

Juan Basin but also have gained insight into processes that have application to the study of other 

commodities in sedimentary basins. 

The Late Jurassic plate tectonic setting of the 

San Juan Basin was integral to ore genesis. Uplift 

in a magmatic arc region several hundred kilometers west of the paleo-basin established stream 

gradients necessary to deliver detritus to the subsiding basin, resulting in deposition of the host 

sandstones (Westwater Canyon Member and 

Jackpile sandstone of economic usage). Volcanism 

in the arc region also supplied abundant volcanic 

ash throughout Morrison deposition. Alteration of 

this air-fall ash in a saline-alkaline lake (Brushy 

Basin Member) was a key element in controlling 

pore-water composition in the Morrison Formation. 

Ore occurs as a pore-filling urano-organic mixture in host sandstones; the organic material is 

the main ore control. Petrographic evidence reveals that the organic material was introduced into 

the host sandstones soon after deposition. Reconstruction of burial history indicates that the time 

of mineralization (Late Jurassic-Early Cretaceous) was not a time of oil generation. Th~se timing constraints, together with chemical studies 

and alteration patterns, indicate that the organic 

material in ore zones was a humic derivative. The 

source of this organic material is the main concern 

in ore genesis. 

Our understanding of the depositional environment of the Brushy Basin Member constrained reconstructions of paleo-basin geometry and also 

explained ore-related alteration patterns in Morrison sandstones; these alteration patterns, in turn, 

aided in reconstructing ore-related hydrohgy and 

pointed to a source for the organic mater~~. The 

paleo-basin geometry can be accurately inferred 

because saline-alkaline lakes develop only in 

closed-basin settings and because mapping authigenic mineral facies in the lake sediments defines the paleo-lake basin. Our reconstructions indicate that the paleo-San Juan Basin, as defmed 

by the paleo-lake, extended well north of the present-day margin. Pore water that descended from 

these paleo-lake sediments altered underlying 

sandstones, and lateral trends in these m<:o.opable 

altered areas parallel the lateral change~· in authigenic mineral facies observed in the oy~rlying 

lake sediments. Detrital feldspar, magnetite, and 

ilmenite grains in the host sandstones refl ~ct this 

downward movement of pore fluids. Mf metite 

and ilmenite grains are of particular inter~st because their alteration can be directly rel~.ted to 

67 
movement of organic-bearing fluids; detailed mapping of these altered mineral grains points to the 

mudflat facies of the Brushy Basin Member as the 

source of these fluids. For this reason, ore is restricted to sandstones that received pore fluids 

from the mudflat facies. 

In terms of the hydrologic history of the basin, 

formation of this organic-rich ore is related to 

early pore-water evolution in a compacting paleobasin (Late Jurassic-Early Cretaceous), whereas 

later redistribution into roll-type uranium ore occurred when oxygenated ground water recharged 

the uplifted basin margin in the Tertiary (postLaramide), when compaction was largely completed. Radiometric dates indicate that this redistribution process continues to the present day. 

Thus, evolution of the San Juan Basin, from deposition of the Morrison Formation to the present, 

was considered in our basin analysis approach to 

ore genesis. 

EVOLUTION OF OIL-SHALE BASINS-EVIDENCE 

FROM SULFUR GEOCHEMISTRY 

M. L. Tuttle and M. B. Goldhaber 

The abundance and botopic composition of 

major forms of sulfur, together with the sulfidemineral morphology and paragenesis, were determined for samples of oil shale-rich Green River 

Formation (Eocene). Our samples came from the 

Green River basin (GRB), Wyoming; the Uinta 

basin (UB), Utah; and the Piceance basin (PB), 

Colorado, from rocks originally deposited as sediment in ancient lake Gosiute (GRB) and in two 

distinct sub-basins in ancient lake Uinta (UB, 

PB). We analyzed organic matter (Corg), iron 

(Fe20 3), total sulfur CStot), pyritic sulfur (Spy), and 

organically-bound sulfur (Sorg), along with the average isotopic composition of the Spy and Sorg' in 

order to determine the evolution of fine-scale 

biogeochemical and geochemical changes occurring 

in the three basins during three lake stages (early, 

fresh-water; intermediate, saline-water; and late, 

fresh-water). The results of our analyses are as 

follows, with values reported as mean abundances 

and isotopic compositions. 

Basin Corg Fe20s Stot Spy Sorg 8MSpy 834Sorg 

pet 

GRB 3.4 3.0 0.82 0.60 0.08 23.4 23.8 

PB 9.8 3.1 1.2 .94 .20 26.2 25.2 

UB 5.0 4.2 .84 .50 .11 25.4 28.2 

Samples from the three basins contain similar 

mean sulfur abundances and have similar mean 

sulfur-isotopic compositions, suggesting that sedimentary-geochemical processes wp·e generally 

similar between the two lake systems. Slight but 

systematic differences in the sulfur, organic carbon, and iron data from the UB and PB do, however, suggest that depositional conditions were 

not uniform within lake Uinta. In addition, the 

evolution of the sedimentary sulfur was different 

in lakes Gosiute and Uinta: isotopic values in samples from UB and PB generally inn.rease higher 

in the stratigraphic section, wher~as sulfur in 

samples from the GRB shows no tendency to 

evolve heavier isotope ratios. Ratios in GRB samples are much more variable than in samples from 

the other two basins. This variabirty is related 

to the volcanic-ash content; the sedimentary sulfur 

becomes enriched in 32S where the S(\diment is enriched in ash. This enrichment relationship 

suggests that the ash provided an increment of 

sulfate to Gosiute's lake waters. 

68 

The diagenetic environment of all these sediments is reflected in the mineralogy of the sulfides 

they contain. Highly unusual, bl-:1.ded sulfides 

occur throughout cores from all thre~ basins. Pyrrhotite is not typical of sedimentary sulfides; however, petrographic evidence indicates both that 

the original mineralogy of this bladed sulfide was 

(and sometimes still is ) pyrrhotite and that this 

mineral formed during a post-ef.rly-diagenetic 

event. Bladed pyrite and marcasite are 

pseudomorphic after pyrrhotite attesting to 

changes in the geochemistry of the E'ediments during late-stage diagenesis. 

Our results show that sulfur geoo.hemistry can 

be used to identify fine-scale chang~s in lake and 

sediment geochemistry occurring as these oil 

shale-rich units were deposited and subsequently 
modified by diagenetic processes. These geochemical changes can then be related to oil-shale quantity and quality, thus increasing our knowledge 

of the genesis of these unusual deposits. 

POTENTIAL GAS GENERATION IN 

SUBDUCTED SEDIMENTS OF THE 

EASTERN ALEUTIAN TRENCH AREA 

Roland von Huene 

Sediment being subducted in the eastern Aleutian Trench has a potential to generate large volumes of gas, even though the content of organic 

carbon in the sediment is low, averaging about 

0.4 percent. This high potential for gas generation 

results primarily from the enormous volume of 

sediment undergoing subduction. Along the eastern Aleutian Arc-Trench system, an average 3-

km-thick sheet of sediment is being subducted at 

the rate of about 60 km per million years. The 

geothermal gradient in this region is generally 

30°Cikm, based on one series of measurements in 

a deep well and on the depth of the base of the 

gas-hydrate zone. Such a gradient suggests a temperature regime in which the maximum gas generation in the subducting sediment occurs beneath 

the upper slope. Thus the sediment of the upper 

slope, as opposed to that of the shelf, could be 

the most prospective for gas accumulation if suitable migration paths and reservoirs are present. 

GEOPRESSURED-GEOTHERMAL 

ENERGY POTENTIAL-1986 

Raymond H. Wallace, Jr. 

The concept of a geopressured-geothermal energy resource was introduced in 1966 by U.S. 

Geological Survey researcher Paul H. Jones. Preliminary characterizations of the resource, estimates of the resource base and predictions of recoverability have been based primarily upon assumed hydrogeologic and production models extrapolated from petroleum industry experience. 

No commercial wells have yet been drilled and 

produced to recover the three energy forms offered by this hybrid resource-geothermal ener69 

gy, natural gas, and mechanical (hydraulic) energy. However, considerable new knowledge of 

geopressured-geothermal aquifer systems has 

been gained within the past decade through USGS 

and other Federally sponsored research, including 

short-term tests of nine wells-of-opportunity and 

long-term tests of four research wells. Continuing 

USGS studies of recoverability are basec primarily on results from these tests. 

Upper Cretaceous to lower Miocene geopressured aquifers, ranging in depth from 9,745 to 

16,750 ft, have been tested. Temperatures of reservoir fluids have ranged from 234° to 327°F and 

salinities have ranged from 12,800 to 190,900 mg/ 

L. The assumption used in USGS estimates of the 

resource base, that geopressured aquifers are 

saturated with methane gas, has been ver~fied; indeed, several of the 13 wells tested prod·.tced gas 

in excess of saturation. N ear-wellbore exsolution 

or presence of a low free-gas phase in the aquifers 

may explain the saturation. In addition. all the 

wells on long-term production have unexpectedly 

produced liquid aromatic hydrocarbon corr--Jounds. 

Flow-rates ranging as high as 36,500 bbls/day 

have been achieved from reservoir vol·:1.mes of 

more than 0.4 mi3 • However, available reservoir 

properties data and well test results are inconclusive in establishing long-term sustained production rates. Permeabilities have been fourd to be 

higher than predicted by conventional techniques 

by a factor of 3 to 5. Most importantly, two of 

the four long-term well tests have reveal€'d a yetto-be-defined reservoir pressure-sustaining 

mechanism. Possible mechanisms include stressdependent compressibility, long-term fc~mation 

creep, shale-water recharge, cross-flow from adjacent sands, and leakage along boundary faults. 

Early production scenarios considered extraction of all three forms of this energy r-~source, 

although hydraulic energy was recogniz~d as a 

minor contributor. In the mid to late 1970's, emphasis was focused on the production of natural 

gas, because of the oil crisis. Within the past 5 

years, production of geothermal energy, along 

with natural gas, has been emphasized. THs year, 

the U.S. Department of Energy and the Electric 

Power Research Institute will begin testir~ an innovative system for recovery of these two re-
sources. The experiment is expected to show that 

each of these two energy forms is of significant 

value and can be selectively produced in response 

to market and other conditions. 

Parametric studies by the USGS, based on the 

preliminary well test results, indicate that more 

than 5 percent of the resource base may be recoverable, particularly if production is enhanced by 

shale-water recharge, an early concept advanced 

by the USGS, and the presence of a low free-gas 

phase in the reservoirs. Recoverability will be 

better defined when the results of on-going longterm well tests become available. 

GEOCHEMICAL PROCESSES AFFECTING THE 

ZONATION OF VANADIUM, IRON, 

AND CHROMIUM, AND IMPLICATIONS 

FOR VANADIUM-URANIUM ORE 

FORMATION IN THE COLORADO PLATEAU 

Richard B. Wanty, George N. Breit, and 

Martin B. Goldhaber 

Tabular, stratabound vanadium-uranium deposits occur in fluvial sandstones of the Salt Wash 

Member of the Morrison Formation (Upper Jurassic) in southwestern Colorado. The ore is associated with coalified organic debris and iron sulfides; ore generally conforms to bedding planes 

but locally crosses them. Laterally displaced from 

the V-U ore bodies by distances of up to 20 meters 

are, in sequence, zones of chromium-rich illitesmectite, and hematite (iron deposits). The iron 

deposits occur in red (oxidized) rock, and the 

orebodies and Cr-clay zones occur in reduced 

(gray) rock. The morphology of the iron deposits 

mimics that of the V-U ore bodies, and the Cr-clay 

layers conform completely to bedding features. 

Understanding the chemical properties of V, Fe, 

and Cr enables us to characterize the hydrochemical processes that formed these deposits. 

Predominant vanadium ore phases include a 

chlorite enriched in V and Fe, and an oxide of 

V, Fe, and Al, which may be similar to the mineral montroseite (ideally VOOH). Vanadium in the 

oxide phase is dominantly trivalent--the most reduced and least mobile form of vanadium observed 

in natural systems. Iron in the oxide phase is dominantly ferric. The conditions of coprecipitation 

of oxidized Fe and reduced V are not well under70 

stood. Laboratory kinetic studies indicate that 

vanadyl ion is rapidly reduced by H2S under conditions of pH and ionic strength that could have 

formed the deposits. Therefore, precrpitation of V 

may have been initiated by reductior of the more 

soluble vanadyl (V02 +) ion by limited local accumulations of H2S in the host roclr. Hydrogen 

sulfide in the system also reacted v.ith dissolved 

iron to form minor amounts of pyrite and marcasite, implying that the ore-forming solutions were 

infrequently supersaturated with res:nect to these 

minerals. 

The ore chlorite phase contains trivalent V and 

divalent Fe. In the chlorite-forming process, the 

vanadium was probably reduced by H2S and incorporated into the lattice with the Fe2 +. The absence of ferric iron in the chlorite suggests that 

the chlorite formed in contact with strongly reducing solutions. 

The Cr-rich illite-smectite is asfnciated with 

coalified detrital organic matter alo'1g thin horizontal bedding planes near the conta n.t of oxidized 

(red) and reduced (gray) sand"'t,ones. The 

chromium was probably concentrat~d by the reduction of dissolved chromate to Cr3 + by reaction 

with the organics and incorporated into the forming clay lattice. 

The iron deposits define the conta n.t of oxidized 

and reduced rocks and consist of bf-lnds of sandstone cemented by vanadiferous h~matite. The 

iron deposits formed simultaneously with the V-U 

deposits, based on petrographic, chemical, and 

geometric similarities. Precipitation of the hematite was probably due to oxidation of ferrous iron 

and subsequent hydrolysis. 

The similar geometric and petrographic relationships of the three zones sugg~st that they 

formed contemporaneously in the same hydrologic 

regime. Local accumulations of organic debris and 

sulfide minerals in the Salt Wash Member caused 

the development of redox gradients. The iron deposits formed farthest from the organic debris 

under the most oxidizing conditions, The Cr-containing clays formed in thin layers of organic debris that were mildly reducing. The most reduced 

conditions favored formation of the V-U deposits 

because the V and U are least soluble under the 

most strongly reducing conditions. The proposed 

local redox gradients, superimposed on the largescale Salt Wash ground-water chemical evolution 

during diagenesis, led to the formation of these 

deposits. 
Llamas were used to install portable seismographs in remote areas of Newberry Volcano, Oregon. Forty field technicians, 

18 mules and horses, 6 wranglers, 6 llamas, and 8 explosives experts were required to field the high-resolution imaging 

experiment. Photograph by Pat Berge, September 1984. 

DEPOSITIONAL CONTlOLS ON THE 

GEOMETRY OF THE WYODAK-ANDERSON 

COAL BED, NORTHEASTERN WYOMING 

Peter D. Warwick and Ronald W. Stanton 

The Wyodak-Anderson coal bed (Paleocene, 

Tongue River Member, Fort Union Formation) is 

extensively mined in an area about 75 mi long by 

10 mi wide that centers around Gillette, Wyoming, on the eastern flank of the Powder River 

Basin. A preliminary study of closely spaced drillhole data (at 500-1,000-ft centers) from a 1,500-

mi2 area in the northern part of the mining region 

indicates that the Wyodak-Anderson coal bed consists of discontinuous, elliptical coal units, generally split into two benches that are separated by 

71 

less than 6ft of siltstone or shale. (However, west 

of our study area, the coal is split by more than 

100 ft of sandstone.) The elliptical coal bodies are 

commonly less than 3 mi wide, 5 mi long, and 80-

120 ft thick; they are separated laterally by narrow (less than 1 mi wide), interconnected no-coal 

or "want" areas. 

The "want" areas in the Wyodak-Anderson coal 

bed are dominated by stacked, medium- to finegrained sandstone units (2fr-50 ft thick) and minor 

interbedded siltstones and shales. These detrital 

units form an east-west-oriented belt that is as 

much as 1 mi wide and can be traced for more 

than 4 mi. Branching out from this belt are merging, smaller (less than 0.25 mi wide) "want" areas 

that extend for more than 6 mi both north and 

south away from the larger east-west-oriented 
belt. Each "want" area laterally interfingers with 

a 1,000-1,500-ft-wide zone of split coal. The splits 

pinch out away from the "want" areas into a zone 

of thickened coal (500-1,000 ft wide) that can be 

as much as 200 ft thick. This thickened coal zone 

then rapidly thins into the central coal body with 

uniform thicknesses of 80-120 ft. Rider beds are 

thickest (as much as 100 ft thick) where underlain 

by "want" areas. Where underlain by thick areas 

of Wyodak-Anderson coal, the riders thin and 

pinch out laterally or merge with the Wyodak-Anderson coal. These riders range from 1 to 2 mi 

long and are less than 1 mi wide. 

The shape and lithofacies of the "want" areas 

indicate that they were probably deposited by 

large east-west- and smaller north-south-oriented 

channels of a larger north-south fluvial drainage 

system whose deposits split the Wyodak-Anderson coal west of our study area. The north-southoriented channels are subparallel to each other 

and appear to merge in a pattern similar to those 

of modern anastomosed fluvial channels. The position of these channels was maintained through 

time by the adjoining thick Wyodak-Anderson 

peat that probably accumulated in place in topographically higher areas, as in an ombrotrophic 

swamp. Mineral-rich zones in the coal adjacent to 

the "want" areas probably represent numerous 

flood events. The thickening of the Wyodak-Anderson coal adjacent to the ''want" areas probably 

reflects differential compaction, which was enhanced by the higher mineral content and different, less compactible plant types than in the areas 

of thick, parting-free peat. Peat accumulation 

ceased in the main Wyodak-Anderson swamp because of increased detrital influx; but in areas underlain by less compactible sandstones and siltstones, higher topography created a platform on 

which rider peat accumulated. 

URANIUM-BEARING SOLUTION-COLLAPSE 

BRECCIA PIPES IN NORTHERN ARIZONA 

Karen J. Wenrich and George H. Billingsley 

Thousands of solution-collapse breccia pipes 

crop out in the canyons and on the plateaus of 

northern Arizona. The pipes originated in the Mississippian Redwall Limestone and stoped their 

72 

way upward through the upper Paleozoic strata, 

locally extending into the Triassic Moenkopi and 

Chinle Formations. Collapse began shortly after 

deposition of the Redwall Limestone, about 300 

m.y. ago, with infilling of the Upper Mississippian 

Surprise Canyon Formation into karst depressions. The dissolution of the Redwall Limestone 

continued to, or at least reactivated during, the 

Triassic. The uranium mineralization apparently 

occurred shortly thereafter: U-Ph isotope data for 

uraninite samples from the Hack Canyon breccia 

pipes suggest a main period of mineralization of 

roughly 200 m.y. ago (K. R. Ludwig, oral commun., 1983). The presence of high-grade uranium 

ore, associated with potentially economic concentrations of Ag, Ph, Zn, Cu, Co, and Ni in some 

of these pipes, has stimulated mining activity in 

northern Arizona despite the depressed uranium 

market. 

More than 900 confirmed and suspected breccia 

pipes have been mapped on the 1,551 mi2 (4,018 

km2

) Hualapai Indian Reservation. The apparent 

density of pipes is greatest in areas where: (1) 

Mississippian rock outcrops occur, (2) the rocks 

are exposed in three dimensions, making the pipes 

easy to recognize, and (3) modern spring activity 

is highest. The springs may follow basement 

structures that have been active since Mississippian time. In addition, many pipes are associated 

with river channels of the Surprise Canyon Formation. This unit is rich in iron and organic detritus and contains the highest background uranium content of any formation within the Grand 

Canyon area. Whether formation of these channels was structurally controlled has not been determined, but pipes mapped on the Marble 

Plateau show distinct northwest and northeast 

alignments, similar to the orientation of faults in 

northern Arizona, suggested by E. Shoemaker in 

1974 to be parallel to basement structures. Many 

mineralized pipes, such as the Hack Canyon pipes, 

occur in clusters. This suggests that the mineralizing fluids had common hydrologic systems possibly using Redwall Limestone caverns or Surprise 

Canyon channels as pathways, moving into those 

pipes connected by the same cave or ancient river 

channel system. 

An extensive suite of elements is anomalously 

concentrated in the breccia pipes: Ag, As, Ba, Cd, 

Co, Cr, Cs, Cu, Hg, Mo, Ni, Ph, Sb, Se, Sr, V, 
Zn, and many rare-earth elements. The principal 

ore minerals are uraninite, chalcopyrite, chalcocite, tennantite-tetrahedrite, galena, sphalerite, 

millerite, gersdorffite, siegenite, and molybdenite. 

Common gangue minerals are marcasite, pyrite, 

barite, dolomite, calcite, and quartz. Marcasite 

and pyrite appear to have formed prior to the ore 

minerals, followed closely by chalcopyrite. The Ni 

and Co phases also appear to be early: gersdorffite 

crystals are rimmed by later galena. Tennantitetetrahedrite formed later than both galena and 

sphalerite. Uraninite, the latest ore mineral, consistently fills interstices. Vuggy quartz, the least 

common gangue mineral, postdates all ore. A 

black, pore-filling pyrobitumen, apparently a late 

phase, rims pyrite, barite, and quartz. 

Primary fluid inclusions in dolomite, quartz, and 

sphalerite show filling temperatures from 80° to 

145°C and high salinities, averaging 15 weight 

percent NaCl (eq). Secondary inclusions in sphalerite have higher filling temperatures from 105° 

to 173°C, but similar salinities. Rock-Eval 

pyrolysis of pyrobitumen by L. Pratt in 1985 

suggests temperatures did not exceed 150°C following pyrobitumen emplacement. 

Except for the presence of uraninite, the breccia pipes are similar to Mississippi Valley-type 

(MVT) deposits in mineralogy, fluid-inclusion filling temperatures and salinities, as well as in the 

presence of associated bitumen. Because MVT deposits do not host uranium minerals, a possible 

two-stage mineralization history of the pipes is 

suggested, the first stage by the MVT brine and 

a second forming the uraninite. Four andesite and 

dacite cobbles associated with the Chinle Formation near Cameron, Ariz., and believed to come 

from the Triassic Mogollon Highland to the south, 

have been dated at 222-196 m.y. by Pierce and 

others in 1985. This age, similar to the 200-m.y. 

U-Pb date on the Hack Canyon uraninite, 

suggests that the volcanic rocks of the Mogollon 

Highland may have been a source for uranium-rich 

fluids that moved northward along the Precambrian unconformity or major Paleozoic sandstone 

aquifers to the low-lying terrane occupied by the 

breccia pipes. Fluids could have been reduced, 

permitting uraninite precipitation, wherever they 

encountered pipes containing the pyrite-rich MVT 

deposits. 

THE USE OF MINERAL ALTERATION PAT""ERNS 

AND STABLE ISOTOPE COMPOSITION~ TO 

INFER A PALEOHYDROLOGIC REGIII~~ 

Gene Whitney, H. Roy Northrop, 

and Paula L. Hansley 

The Westwater Canyon Member of the Upper 

Jurassic Morrison Formation in the southo.rn part 

of the San Juan Basin, New Mexico, exhit•ts mineral and isotopic zonation that can be used to infer 

the conditions of fluid movement and the subsequent mineral-fluid reactions over a distance of 

at least 60 km. The Westwater Canyon Member 

is a relatively homogeneous, hydrologicr.lly continuous 100-m-thick sequence of massive fluvial 

sandstones that is bounded above and b~low by 

relatively heterogeneous, hydrologically discontinuous units. It thus has served as a prim~ry conduit for fluids within this stratigraphic interval. 

We have defined zonation patterns for tl'ree key 

variables that reflect the nature of the mineralfluid reactions: the abundance and miner~.logy of 

the interstitial authigenic clay minerals, tl'o. stable 

isotope composition of the clay minerals, and the 

etching of certain framework grains. Wi~hin the 

Westwater Canyon Member, the proportion of illite layers in diagenetically altered interst.ratified 

illite/smectite (liS) ranges from 0 to 90 percent. 

The sandstone is most illitic at the center and becomes progressively less illitic toward the upper 

and lower contacts. Furthermore, the sr'ldstone 

is most illitic near the center of the basin and becomes less illitic toward the basin margin. The 

abundance of authigenic chlorite correlates positively with the proportion of illite layer~ in the 

liS, suggesting that the chlorite was precipitated 

by the same fluid that drove the illitizati 1n reaction. 

The oxygen and hydrogen isotopic composition 

of the clay minerals is zoned in a similar manner. 

The 3180 and 3D values of the clays are a function 

of the illite content of the liS, with 3180 values 

ranging from + 15 per mil (relative to SMOW) for 

smectite to + 12.3 for the most illitic liS. The 3D 

values range from -116 for smectite to -77 per 

mil for illitic 1/S. The 3180 value for the chlorite 

is + 7.3 per mil for all points in the stucy area. 

The degree of illitization and the isotopic composition of the clays suggest a fluid temperr.ture of 

73 
around 130°C and fluid 8180 and 8D values of + 3 

and -50 per mil, respectively. These values are 

similar to those measured in oil field brines from 

other midcontinent basins. 

The distribution of diagenetically etched detrital 

garnet is nearly identical to that of liS and chlorite in the Westwater Canyon Member. The most 

deeply etched garnets occur where liS is the most 

illitic and chlorite is the most abundant. Outside 

the zone of etched grains, detrital garnets are well 

rounded with smooth, unetched surfaces. Laboratory experiments have shown that warm (>75°C) 

organic-acid-bearing solutions can create etch features on garnets that are identical to the distinctive, crystallographically controlled etch faces on 

Westwater Canyon Member garnets. These results and known concentrations of organic matter 

in the Westwater Canyon Member suggest that 

the hydrolysis of organic matter may have produced the soluble organic acids responsible for the 

etching. 

These patterns of mineral-fluid reactions 

suggest a basinwide paleohydrologic regime in 

which warm, evolved fluids have migrated updip 

from the center of the basin under the influence 

of a regional hydraulic head. The reactions probably resulted from a brief, tectonically induced 

pulse of fluid. Such a fluid movement event is consistent with the movement of petroleum-related 

fluids in overlying rocks during the Tertiary in 

the San Juan Basin. 

TECTONICS-A FIRST-ORDER CONTROL OF 

SEDIMENT DISTRIBUTION AND HYDROCARBON 

POTENTIAL: EXAMPLES FROM THE 

WESTERN MARGIN OF NORTH AMERICA 

Thomas J. Wiley 

Tectonic setting is one of the first-order controls 

that affect the distribution and hydrocarbon potential of thick sedimentary sequences. Comparative studies of divergent, transform, and convergent margins suggest a positive correlation between tectonic setting and basin morphology, rock 

types, heat flow, and rates of sedimentation, subsidence, and uplift. Tectonic setting therefore affects both the quality of source and reservoir beds 

and the timing of hydrocarbon generation, migration, and pooling. The continental margin of Western North America includes divergent tectonics in 

74 

northern Alaska (production and proven reserves 

of 11.79 billion bbl of oil and 35.34 TCF of gas) 

and the Gulf of California; transfo~ tectonics 

along the San Andreas and Queen Charlotte-Fairweather fault systems (production ard proven reserves of 25.63 billion bbl of oil and 25.14 TCF 

of gas along the San Andreas system); and convergent tectonics in southwestern Alask~ (production 

and proven reserves of 1.15 billion lhl of oil and 

7.99 TCF of gas) and northern California to southwestern British Columbia (production and proven 

reserves of 0.17 TCF of gas). Although hydrocarbon shows have been reported from each margin 

segment, the major producing basins occur along 

the San Andreas fault in central r.nd southern 

California, at Cook Inlet, and on the North Slope. 

Only Neogene-sourced oil and gas accumulations 

along the San Andreas fault syste~ developed 

within a single tectonic setting. Sorro. of California's Great Valley fields, and Alaska'E' North Slope 

and Cook Inlet fields, owe their largo. oil and gas 

deposits to changes in tectonic setthg, to accretion of allochthonous terranes, or to overprinting 

of different tectonic styles. 

Gas-prone Cretaceous and Paleogene source 

beds in the Great Valley of California originally 

formed on a convergent margin. Tl'~ change to 

a transform setting in the San J oacuin segment 

resulted in deep burial of the older section by 

Neogene strata. Transform-related en echelon 

folding in the Neogene created large structural 

traps along the valley's western side, and easterly 

regional dips allowed migration of hydrocarbons 

from deeply buried source rocks to tho.se traps. 

Mesozoic source rocks for Cook Inlet oil and gas 

fields developed on a convergent mar<rin that was 

later modified by wrench tectonics. P.~.leomagnetic 

data from the Peninsula terrane indicate that Mesozoic (Jurassic) source beds were deposited in 

lower latitudes and subsequently transported 

northward and accreted to Alasl·a. Neogene 

wrench faulting buried the Mesozoir. strata with 

a thick Tertiary section, and hydrocarbons moved 

from the older rocks into reserYoirs in the 

younger sequence. 

The North Slope of Alaska lies or a divergent 

margin that formed when the l. .rctic Ocean 

(Canada Basin) opened in Late Jurassic to Early 

Cretaceous time. However, source beds for the 

oil in the large North Slope fields are probably 

Cretaceous strata deposited in the Colville 

foredeep to the south. Presumably a large back-
arc basin related to Alaska's Pacific margin, the 

foredeep was created by isostatic loading of adjacent crust with thrust sheets of the Brooks 

Range. 

The Beringian margin (Bering shelf and slope) 

remains largely undrilled. Seismic data show a 

thick sequence of strata underlain by oceanic crust 

at the base of the slope and en echelon structures 

in acoustic basement overlain by a thick sedimentary sectinn at the edge of the shelf. The most 

likely history for this margin segment is thus a 

combination of transform motion and oblique convergence, a tectonic style that is similar to the 

hydrocarbon-rich central and southern California 

transform margin. 

ENERGY RESOURCE PROGRAMS 

The following abstracts overview and tie together research discussed in detail in preceding 

pages: they show the interrelation and cooperation 

among USGS programs and scientific groups, as 

well as the broad extent of USGS energy research. These abstracts briefly explain the various 

Energy Resource Programs, dealing with oil and 

gas, oil shale, coal, geothermal energy, uranium 

and thorium, and the evolution of sedimentary basins; a detailed explanation of each program is 

presented in a poster session. The programs have 

the following goals: 

To assess the energy resource potential of specific 

areas in the United States (particularly Federal lands) for resource management and Congressional action. 

To provide timely assessments of the Nation's energy resources. Such information is important 

for foreign and domestic policy decisions and 

for long-range planning related to energy supply. 

To develop information on the quality of such energy resources as coal and oil shale and other 

unconventional hydrocarbon resources as a 

basis for decisions on technology development 

and resource utilization. 

To identify new areas for exploration and develop 

new concepts of energy deposit formation and 

distribution to increase our known energy resources. 

To improve current methodology and develop new 

techniques for identifying and evaluating ener75 

gy resources and analyzing resource data more 

efficiently and more precisely. 

USGS energy resource assessments are used in 

land-management decisions at all levels of government, from the Congress and the Executive 

Branch of the Federal Government to S~ate and 

local governments, and may also provide planning 

baseline information to industry. Resource and 

geoscience data generated through the programs 

provide basic information used for long-range 

planning for availability of energy resour-:-es on a 

national and international scale. 

THE U.S. GEOLOGICAL SURVEY 

OIL SHALE PROGRAM 

Thomas D. Fouch and John R. Dy~r~ 

The full responsibility for United States Government geologic studies of oil shale and associated deposits is assigned to the U.S. Geological Survey. The goals of the USGS Oil Ehale Investigations Program are: 

To increase our knowledge of the geology 

and chemistry of oil shales and as8ociated 

metals and industrial minerals; 

To understand the basic geolo[ric and 

geochemical processes that form f.nd preserve oil shale in nature and deter-nine its 

quality; 

To apply this knowledge to the development of regional and national reso·.u-ce assessments; 

To characterize the geology, min o.ralogy, 

and chemistry of oil-shale rocks so that the 

shale-oil resources may be maximally 

exploited with minimum environmental impact; 

To develop laboratory and field methods for 

assessing the quantity and quality of oilshale deposits. 

The Oil Shale Investigations Program concentrates much of its effort on research topics and 

geographic areas in which study results can be expected to affect government and indurtry activities most significantly. Historic oil-sha1o. investigations have concentrated on field and laboratory studies of the lacustrine Eocene Gree"l River 

Formation of Utah, Colorado, and Wyoming, 

focusing on the content and quality of oil shale 
on or near sites of current or proposed mining activity. The results of these studies are published 

resource maps of selected shale units and detailed 

geologic maps of parts of the Piceance and Uinta 

basins in Utah and Colorado. In addition, published reports include multidisciplinary baseline 

studies on the chemistry and mineralogy of oil 

shale and surficial materials. New program objectives place increased emphasis on determining the 

mineralogy and chemistry of oil-shale units. 

Plans for fiscal 1986 underscore compilation of 

the geologic framework, fracture network, 

mineralogy, and geochemistry of Green River 

Formation rocks in the northern part of the 

Piceance basin and for parts of the Uinta Basin. 

Although the general extent of the oil-shale resource is known, its development potential is restricted by water-conducting fracture systems, 

and by chemical and mineralogical variations that 

result from variations in the lake's depositional 

character in space and time. Therefore, the program emphasizes geologic and geochemical studies 

that will determine the amount and distribution 

of (1) associated sodium-aluminum minerals that 

are potentially useful by-products of oil-shale processing, (2) minerals which may adversely affect 

shale-retorting processes, and (3) host minerals 

that might contain minor and trace elements of 

environmental concern. Studies of the chemistry 

and stable isotope composition of mineral species 

will determine the depositional and diagenetic history of the shales and its relation to chemical and 

mineral variations. Ongoing mapping and studies 

of water-conducting fracture systems should allow 

more effective utilization of oil-shale resources. 

Results of these new multidisciplinary studies 

will be compiled as geologic maps and reports that 

discuss a wide range of factors relative to effective 

characterization and utilization of the resources. 

Other efforts will concentrate on mapping and 

study of other oil shales and organically enriched 

rocks in the western part of the United States, 

and on developing and testing new methods for 

determining shale-oil yields and shale-oil quality 

from rocks. Research of the USGS Oil Shale Program has served and will continue to serve the 

geologic needs of industry, members of the scientific public, and governmental agencies involved 

in development planning and regulation. 

THE U.S. GEOLOGICAL SURVEY EV<')LUTION 

OF SEDIMENTARY BASINS PRO~RAM 

Thomas D. Fouch, B. H. Kent, 

J. W. Schmoker, J. L. Ridgley, 

K. J. Englund, and K. J. Bird 

Rocks of sedimentary basins host most of the 

United States' energy resources, m('~t of its industrial and agricultural minerals, and a large 

proportion of its metallic-mineral res'lurces. Several U.S. Geological Survey programr, focused on 

specific energy and metal commodities, presently 

investigate specialized geologic probbms in sedimentary units. Because the collectiY~ impact of 

these studies leaves a large number of basic 

geologic questions unanswered, the Evolution of 

Sedimentary Basins Program (ESB) was initiated 

in October 1984. ESB is a broad-bar~d scientific 

approach to understanding processef at work in 

sedimentary basins and rocks. The p1.;ncipal goals 

of the ESB Program are five-fold: 

1. To provide a coordinated and multidisciplinary approach to research studies of the evolution 

and constituents of sedimentary barins. Studies 

include sedimentary-rock geology, cr:tstal processes, tectonic evolution, geothermometry, 

paleohydrology, petrography, g~ochemistry, 

sedimentologic and depositional eYolution, organic-matter content and thenral history, 

lithofacies and biological facies, and habitats of 

mineral and energy resources. 

2. To explore the chemical and :rhysical composition, history of movement, and i1.teraction of 

mineral and sediment grains, biologic constituents, and fluid or gaseous matter through 

various stages of lithification and alteration during 

basin burial and uplift. 

3. To form an integrated geologi ~ framework 

using new information from surfac~~-rock exposures, in combination with borehole geophysical, 

electrical, and lithologic logs, and cored-rock, 

gravity, magnetic, and seismic-reflection and refraction studies. 

76 

4. To develop and distribute new maps, 

charts, analyses, and other data, and to offer 

state-of-the-art interpretation of this information. 

5. To provide data and interpretations so that 

resource and hazard evaluations can be developed 

in a timely manner. 
Initial program studies are directed at understanding the physical and chemical evolution of 

the geologic framework of four geologically diverse basins: (1) the North Slope basin, Alaska; 

(2) the Anadarko basin, Oklahoma, Texas, and 

Kansas; (3) the Powder River basin, Wyoming and 

Montana; and ( 4) the Central Appalachian basin, 

West Virginia, Virginia, Tennessee, and Kentucky. Subsequent paleohydrologic and diagenetic 

studies will rely on and be placed in the context 

of the established basin framework. Additional 

ESB-type efforts are underway in the San Juan 

and Uinta/Piceance basins. 

Results of these Evolution of Sedimentary Basins studies serve ·industry, governmental agencies, colleges and universities and associated scientists, and other members of the technical public 

whose concerns require insight into the evolution, 

nature, and geologic character of sedimentary basins and rocks. 

THE U.S. GEOLOGICAL SURVEY URANIUM 

AND THORIUM PROGRAM 

Thomas D. Fouch and Jennie L. Ridgley 

In 1984, the full responsibility for the geologic 

resources studies of uranium and thorium deposits 

was passed from the U.S. Department of Energy 

(DOE) to the USGS. The transfer of that responsibility has somewhat altered the USGS basic science program of uranium and thorium investigations to reflect the Survey's requirement to respond to the Nation's need for basic information 

on uranium and thorium geology and resources. 

As a result, the current goals of the USGS U ranium and Thorium research program are (1) to improve the understanding of the geologic habitat 

and distribution of identified domestic resources 

of uranium and thorium, (2) to apply this understanding to the development of regional guides to 

assess the undiscovered resources, and (3) to 

develop techniques for increasing the discovery 

rate and exploitation of economically recoverable 

nuclear raw materials. Attainment of these goals 

permits the USGS to advance the basic science 

of uranium and thorium geology, to provide information on undiscovered uranium and thorium endowment to the Energy Information Administra77 

tion (EIA) of the DOE, and to assess the validity 

and utility of data sets and samples collected 

under the DOE's National Uranium Resource 

Evaluation (NURE) program. 

The Uranium and Thorium program concentrates much of its effort on topics or geographic 

areas where study results can be expected to affect estimates of undiscovered uranium and 

thorium endowment most significantly. Four 

major geographic and topical areas for new emphasis have been identified, and program resources are being focused in these areas. They are 

(1) surficial uranium deposits (SUDS) throughout 

the United States, (2) uranium in sedimentary 

breccia pipes of the southern Colorado Plateaus, 

(3) uranium in metamorphic rocks of the Piedmont 

physiographic province of the Eastern United 

States, and (4) uranium in sedimentary rocks of 

the northern Great Plains. These and other program geologic research studies that are continuing 

in sedimentary, igneous, and metamorphic rocks 

in various parts of the United States will produce 

topical scientific products in the fields of 

radiogenic and stable isotopes, paleoground-water 

movement, water-water and rock-water reactions, 

geochemical redox systems, and organic geochemical-metal deposit relations. 

The SUDS project has been examining uraniferous organic-matter-rich sediments in surficial environments in several Western, Rocky Mountain, 

and Northeastern States. These uraniferous sediments commonly are developed in mountain terrain underlain by granitic rocks. A Holocene 

boggy meadow in Washington State is currently 

being mined for uranium. Other surficial deposits 

of the Southwest United States and southwestern 

Great Plains are associated with caliche formation. 

In northern Arizona, Paleozoic formations contain breccia pipes filled with blocks of country 

rock (sandstone, shale, and limestone). Some 

pipes are mineralized with uranium, copper, 

cobalt, and precious metals. Mineralized pipes in 

the region contain small but rich uranium 

orebodies, some of which are now the focus of 

mining activity. 

In Virginia, altered Paleozoic metamorphic 

rocks of the Piedmont province are locally rich in 

uranium minerals. Similar occurrences may exist 

elsewhere in the province where tectonic and 

mineralizing events seem comparable. 
USGS Uranium and Thorium program efforts, 

begun before 1984, will continue in the San Juan 

and other Rocky Mountain basins, in the Lake 

City caldera region of southwest Colorado, and 

through topical studies of world-class uranium deposits. 

Breaking the silence of an Alaskan midsummer night a 3 000-

lb explosion detonated in the terminus of the Rude River 

glacier in the Chugach Mountains generates seismic waves 

being used to decipher crustal structure along the transAlaska pipeline corridor. This glacier pond south of Cordova 

Peak near the Contact fault-suture between Chugach and 

Prince William terranes--was used both as an intermediate 

shotpoint on a 120-km seismic refraction profile extending 

from Copper River delta due north across suture zone and 

as an off-end shotpoint on a 135-km strike profile within 

Prince William terrane extending across Hawkins, Hinchinbrook, and Montague Islands. Original color slide by G. S. 

Fuis, June 1985. 

78 

THE U.S. GEOLOGICAL SURVEY 

COAL RESOURCES PROGRAM 

H. J. Gluskoter 

The USGS coal program is interdisciplinary in 

nature, and much cooperative research involving 

several areas of the USGS is currently underway. 

These efforts include microcomputer system development, organic geochemistry investigations, 

isotopic and elemental analyses, and hydrologic, 

paleontologic, paleoecologic, paleobotanic, and 

mapping studies. The USGS Coal Resources Program has as its primary purpose the development 

of a scientific understanding of the origin, distribution, mode of occurrence, character, and extent 

of the coal resources of the Nation. The coal program consists of three subprograms: (1) Coal Investigation Studies, (2) National Coal Resources 

Data System (NCRDS) and Information Transfer 

Studies, and (3) Coal Basin Analysis, a subprogram designed specifically to contribute to the 

Evolution of Sedimentary Basins Program. 

The goals of the Coal Investigation Program 

are: 

To produce scientifically based assessments 

of the quality and quantity of United States 

coal resources. 

To understand the geological and chemical 

processes and conditions existing during 

coal formation, and the influence of those 

processes and conditions on coal quality. 

To determine the basic chemical nature of 

coal and the distribution of contaminants 

such as sulfur, ash and other impurities 

which affect the environmentally acceptable 

utilization of the coal. 

To develop predictive models for the origin 

and distribution of the chemical components 

of coal. 

To develop and maintain a computerized 

National Coal Resources Data System that 

provides USGS scientists, other Federal 

and State scientists, and the public sector 

ready access to a large collection of information on the Nation's coal resources. 

To provide geotechnical, geochemical, and 

other basic geologic data to those concerned 

with coal exploration, coal production, and 

coal utilization, so that these activities may 

be carried out in an efficient, safe, and environmentally acceptable manner. 
Major accomplishments of the program in fiscal 

1985 include (a) transfer of NCRDS from a central 

computer to a mini-computer system, which will 

lower operating costs, allow for the addition of a 

geostatistical program for performing coal deposit 

assessments, and make the system more accessible to all users; (b) entry of 30,000 records of drillhole data in NCRDS; (c) completion of coal resources assessments for 30 counties in 7 States 

(Colorado, Kansas, Missouri, Montana, Pennsylvania, Texas, and Virginia); (d) completion of a 

summary report for the U.S. Department of Energy on the distribution of certain chemical elements in the coals on record in the U.S. Bureau 

of Mines Coal Reserve Base; (e) completion of 

coal-geologic and engineering and hazards studies 

for ten 1:100,000-scale quadrangles in the West as 

part of the coal-folio project; (0 realignment of 

coal basin studies to concentrate about 50 percent 

of effort on analyses of coal-bearing basins; (g) 

support for rlP.velopment of a method to remove 

pyrite from coal by first producing a ferro-magnetic particle (patent applied for); (h) completion 

of reports on a study of the geologic factors that 

control variations of mineral matter in the Upper 

Freeport coal bed, central Pennsylvania; (i) completion of a summary of the coal resources of the 

National Petroleum Reserve of Alaska; (j) compilation of the coal geology map of North America; 

(k) assistance with coal geology studies in China, 

Costa Rica, and the Philippines; and (l) publication 

of a predictive model of the development of fossil 

fuels and mineral deposits in rift valleys. 

THE U.S. GEOLOGICAL SURVEY 

GEOTHERMAL RESEARCH PROGRAM 

L. J. Patrick MuHier and Manuel Nathanson 

The goal of the USGS Geothermal Research 

Program is to understand the nature, distribution, 

and magnitude of geothermal resources of the 

United States, as a basis for determining the 

proper role of geothermal energy as one alternative energy source in national energy policy. This 

goal is accomplished through multidisciplinary research designed to (1) determine the geological 

and hydrological factors that control the characteristics, occurrence, longevity, and size of all 

types of geothermal systems; (2) estimate the location and magnitude of the Nation's geothermal 

resources, periodically updating these assess79 

ments as new information becomes availr.ble and 

assessment methodologies are refined; and (3) 

evaluate geoenvironmental effects atten1ant to 

extraction and injection of geothermal fluids. 

The Geothermal Research Program in the 

1970's and early 1980's focused on hydr<'i;hermal 

convection systems, generally at depths less than 

3 km. Major accomplishments included (1) three 

national assessments of geothermal resources; (2) 

comprehensive multidisciplinary studies of major 

geothermal regions, including The Geyser~. Long 

Valley, Coso, Yellowstone, Raft River, and the 

Snake River Plain; (3) development of new 

methods to interpret water and gas ana lyses to 

give subsurface temperatures and to elucidate reservoir processes; (4) development of electlical and 

electromagnetic techniques to determine the 

geometry of geothermal systems; (5) development 

of various passive and active seismic techniques 

for investigation of hydrothermal systems and underlying intrusive complexes; and (6) development 

of hydrologic models to describe matheratically 

the behavior of geothermal systems. 

The current trends of the Geothermal Research 

Program are a decreasing emphasis on the shallower hydrothermal convection systems and increasing emphasis on all types of geothenr 111 energy (including magma and hot dry rock) as~0ciated 

with young igneous systems. The current program 

has five major components: 

A multiyear, multidisciplinary pro:rram to 

understand the tectonics, geology, and hydrology of the Cascade Range as a 

framework for characterizing and quantifying the geothermal resources of the range. 

Isotopic and chemical studies to refine 

geothermometers, elucidate hydrcthermal 

processes, determine the origin of chemical 

constituents in geothermal fluids, r.nd contribute to the reservoir engineering of geothermal reservoirs under development. 

Increased study of young igneous ~ystems, 

in particular, development of advanced seismic tomographic techniques to identify and 

characterize magma bodies. 

Studies of the interaction of magma and 

geothermal fluids in the roots of hydrothermal systems, focusing on the physical and 

chemical processes by which energy and 

mass are transported through the crust in 

volcanic areas. 
Investigations into selected geoenvironmental concerns of geothermal development, including seismic activity in areas 

under production and evaluation of the extent to which thermal features in national 

parks might be affected by geothermal development in adjacent areas. 

Cooperation with the U.S. Department of 

Energy, the U.S. Agency for International 

Development, and foreign governments in 

the evaluation of geothermal energy in 

Latin America. 

U.S. GEOLOGICAL SURVEY ONSHORE 

OIL AND GAS PROGRAM 

Dudley D. Rice 

The Onshore Oil and Gas Program consists of 

basic and applied research focused on both topical 

and regional problems related to the origin, migration, accumulation, and resource assessment of 

hydrocarbons. The objectives of the program are 

to develop and apply concepts and techniques that 

will improve our ability to better understand 

mechanisms that lead to generation of hydrocar80 

bons from suitable source beds, as well as identify 

resource potential, especially in Fro11tier areas, on 

Federal lands, and from unconventional sources. 

Attainment of these objectives requires a multidisciplinary approach, utilizing both field and laboratory studies. 

At present, the Onshore Oil and Gas Program 

is concentrated on (a) hydrocarbon resource assessment of Federal lands of United States and 

foreign countries; (b) production of maps for the 

Atlas of Oil and Gas Information; (c) geologic 

characterization of unconventional hydrocarbon 

resources, such as coal-bed gas, gas hydrates, Devonian black shales, and tight gas s~nds; (d) construction of Thermal Maturation Map of the 

United States; (e) geologic characterization and 

hydrocarbon resource assessment of the Arctic 

National Wildlife Refuge (ANWR); (f) seismic 

studies concerned with mapping of subsurface 

structures and stratigraphy; (g) the use of Artificial Intelligence (AI) as an aid in identifying depositional environments; (h) geoche:"llical investigations of hydrocarbon-forming p ... ocesses and 

their relation to mineral-forming processes; (i) 

studies of modern and ancient sec1'mentary sequences, leading to prediction of r~servoir- and 

source-rock distribution and properties; and (j) 

structural studies focusing on overthr11st belts. 
ORGANIZATION OF THE U.S. GEOLOGICAL SURVEY 

Office Name Telephone City 

OHice of the Director 

Director Dallas L. Peck 703/860-7 411 Reston 

Associate Director Doyle G. Frederick 703/860-'7 412 Reston 

Assistant Director for Research 703/860-7 488 Reston 

Assistant Director for Engineering Geology James F. Devine 703/860-7491 Rest,Jn 

Assistant Director for Administration Edmund J. Grant 703/860-7201 Reston 

Assistant Director for Programs Peter F. Bermel 703/860-7 435 Reston 

Assistant Director for Intergovernmental Affairs John J. Dragonetti 703/860-7 414 Reston 

Chief, Public Affairs Office Donovan B. Kelly 703/860-7 444 Reston 

Assistant Director for Information Systems James E. Biesecker 703/860-7108 Reston 

National Mapping Division 

Chief Rupert B. Southard 703/860-6231 Reston 

Geologic Division 

Chief Geologist Robert M. Hamilton 703/860-6531 Reston 

Water Resources Division 

Chief Hydrologist Philip Cohen 703/860-6921 Reston 

ORGANIZATION OF THE GEOLOGIC DIVISION 

OHice of the Chief Geologist 

Chief Geologist Robert M. Hamilton 703/860-6531 Reston 

Associate Chief Geologist William F. Cannon 703/860-6532 Reston 

Assistant Chief Geologist for Program Benjamin A. Morgan 703/860-6584 Reston 

Assistant Chief Geologist, Eastern Region Bruce R. Doe 703/860-6631 Reston 

Assistant Chief Geologist, Central Region Harry A. Tourtelot 303/236-5438 Denver 

Assistant Chief Geologist, Western Region Carroll Ann Hodges 415/323--8111 Menl~ Park 

OHice of Mineral Resources 

Chief Glenn H. Allcott 703/860-6561 Reston 

Chief, Branch of Alaskan Geology Donald J. Grybeck 9071786--7 403 Anch"~rage 

Chief, Branch of Eastern Mineral Resources Bruce R. Lipin 703/860-6913 Reston 

Chief, Branch of Central Mineral Resources Charles H. Thorman 303/236--5568 Denver 

Chief, Branch of Western Mineral Resources Edwin H. McKee 415/323--8111 Menl1 Park 

Chief, Branch of Exploration Geochemistry Byron R. Berger 303/236--1800 Denver 

Chief, Branch of Resource Analysis Lawrence J. Drew 703/860-6446 Reston 

Chief, Branch of Analytical Chemistry Philip A. Baedecker 703/860-7246 Reston 

Chief, Branch of Geophysics Frank C. Frischknecht 303/236--1212 Denver 

OHice of Energy and Marine Geology 

Chief Terry W. Offield 703/860-6431 Reston 

Chief, Branch of Oil and Gas Resources Dudley D. Rice 303/236--5711 Denver 

Chief, Branch of Coal Resources H. J. Gluskoter 703/860-7734 Reston 

Chief, Branch of Energy Minerals Thomas D. Fouch 303/236--1644 Denver 

Chief, Branch of Pacific Marine Geology Monty A. Hampton 415/856--7141 Menh Park 

Chief, Branch of Atlantic Marine Geology Robert B. Halley 617 /54S-8700 Woods Hole 

81 
Office Name Telephone 

Office of Regional Geology 

Chief Eugene H. Roseboom 703/86{}..-6.411 

Chief, Branch of Eastern Regional Geology Gregory S. Gohn 703/86{}..-6404 

Chief, Branch of Central Regional Geology Kenneth A. Sargent 303/236-1258 

Chief, Branch of Western Regional Geology Robert 0. Castle 415/323-8111 

Chief, Branch of Isotope Geology John Rosholt 303/236-7882 

Chief, Branch of Astrogeology Gerald G. Schaber 602/527-7015 

Chief, Branch of Paleontology and Stratigraphy Richard Z. Poore 703/860-728!} 

Office of Earthquakes, Volcanoes, and Engineering 

Chief John R. Filson 703/86{}..-6.47:' 

Chief, Branch of Engineering Seismology and Geology Thomas C. Hanks 415/323-8111 

Chief, Branch of Global Seismology and Geomagnetism Robert P. Masse 303/236-1510 

Chief, Branch of Seismology William L. Ellsworth 415/323-8111 

Chief, Branch of Engineering Geology and Tectonics Albert M. Rogers 3031236-1585 

Chief, Branch of Tectonophysics Wayne R. Thatcher 415/323-8111 

Chief, Branch of Igneous and Geothermal Processes L.J. Patrick Muffler 415/323-8111 

Office of Scientific Publications 

Chief John M. Aaron 703/860-6575 

Office of International Geology 

Chief A. Thomas Ovenshine 703/86{}..-6.418 

Addresses 

U.S. Geological Survey 

Reston, VA 22092 

U.S. Geological Survey 

Box 25046 

Denver Federal Center 

Denver, CO 80225 

U.S. Geological Survey 

345 Middlefield Road 

Menlo Park, CA 9402f 

City 

Reston 

Reston 

Denver 

Menlo Park 

Denver 

Flagstaff 

Reston 

Reston 

Menlo Park 

Denver 

Menlo Park 

Denver 

Menlo Park 

Menlo Park 

Reston 

Reston 

U.S. Geological Survey 

Branch of Alaskan Geology 

4200 University Drive 

Anchorage, AK 99508-4667 

U.S. Geological Survey 

2255 North Gemini Drive 

Flagstaff, AZ 86001 

U.S. Geological Survey 

Quissett Campus, Bufding B 

Woods Hole, MA 02M3 

U.S. Geological Survey 

Hawaiian Volcano Observatory 

Hawaii National Park 

HI 96718 

82 

U.S. Geological Survey 

David A. Johnston Cascades Volcano Observatory 

5400 MacArthur Boulevard 

Vancouver, WA 98661 
AUTHOR INDEX 

Page 

Affolter, R. H. ................................................... 59, 65 

Ambos, E. L. . . . . . . . . .. . . . . . . . . . . .. . . . . . ... .. . . . . . . . . . .. . . . .. . . . . .. . . . 50 

Anders, D. E. .. . . . . . . .. . . . . . .. . .. . . . . . . . . . . .. . . . . .. . . . .. . .. . . . . . . . 1, 61 

Attanasi, E. ............................................................ 27 

Back, J. M. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9, 11 

Ball, M. M ................................................................ 2 

Baltz, E. H. ............................................................. 3 

Barron, J. A. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 

Barton, C. C. .. . . .. . .. . . . . . . .. . . . . . . . . . .. . . .. ... . . .. . ... . .. . . . . . . . .. .. . . 4 

Beyer, L. A. .......................................................... 19 

Biewick, L. H. . . . .. . . . . . . .. . .. . . . . . . . . . . . . . .. . . . . . . .. . .. . . . . . . . . . ... . . 43 

Billingsley, G. H. .................................................... 72 

Bird, K. J. .............................................. 6, 11, 43, 76 

Bisdorf, R. J. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 

Blank, Herma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 

Boger, L. W. .... ....•.... ...... ....................................... 43 

Breit, G. N. ........................................................... 70 

Bromfield, C. S. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 

Brown, F. W. ......................................................... 36 

Brown, Z. A. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 

Brownfield, M. E. ................................................... 65 

Burruss, R. C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. . 21, 57 

Cacchione, D. A. ..................................................... 13 

Cameron, C. C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 

Campbell, D. L. ...................................................... 50 

Cecil, C. B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8, 9 

Chao, E. C. T. . . . . . . . .. . . .. . . . . . . . . ... . .. .. . . . . .. . .. . . .. . .. . 9, 11, 42 

Claypool, G. E. ................................................... .... 11 

Clayton, J. L. ......................................................... 21 

Collett, T. S. ..................................................... 11, 43 

Cooper, A. K. . .. . . . . . . . . . .. . . . . . . . . . .. . . .. . .. . . .. . . .. . . . . . . . . . . . . .. . . . 12 

Crowley, S. S. . . . . . . . . . . .. . .. . . . . . . .. . . .. . . .. . .. . . .. . .. . . . . . . . .. . . . . . . 11 

Dawson, P. B. ........................................................ 15 

Desborough, G. A. .................................................. 30 

Dolton, G. L. . . .. . . . . . . . . . .. . . . . . . . . . .. . . .. . .. . . .. . . .. . . . . . .. . . . . . 27, 37 

Donnelly-Nolan, J. M. ...... ........................................ 12 

Drake, D. E. :......................................................... 13 

Drew, L ................................................................. 27 

Dulong, F. T. ........................................................... 9 

Dyni, J. R. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 

Edwards, B. D. ...................................................... 13 

Englund, K. J. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 

Evans, J. R. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 

Field, M. E. ........................................................... 13 

Finch, W. I. ........................................................... 17 

Fisher, M. A. ......................................................... 50 

Fishman, N. S. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58, 67 

Fitterman, D. V. . . . . .. . .. . . . . . .. . . . . .. . . . . . . . . . . . . . . . . . .. . .. . . .. . . .. . 16 

Fletcher, J. D. ......... .. .. ........ ............ .... ..... ......... ..... 36 

Flores, R. M. ......................................................... 20 

Fouch, T. D. ................. .. ............................. 75, 76, 77 

Fox, J. E. .............................................................. 37 

Franczyk, K. J. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 

Frishman, David . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 

Froelich, A. J. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 

Fuis, G. S. ............................................................. 50 

Gardner, J. V. ........................................................ 13 

Page 

Gardner, N. K. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . 43 

Gautier, D. L. ................................................... 16, 61 

Gluskoter, H. J ... ,................................................... 78 

Goldhaber, M. B. ................................... 44, 58, 68, 70 

Gottfried, R. M. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 

Granger, H. C. ....................................................... 17 

Grauch, R. I. .......................................................... 45 

Green, M. W. . . . . . . . . . . . . . .. . . . .. . . . . . . .. . .. . . . . . . . . . . . .. .. . .. . ... .. . . 17 

Grow, J. A. ............................................................ 57 

Gundersen, L. C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 

Hackney, P. I. ........................................................ 62 

Halley, R. B. .......................................................... 19 

Hampton, M. A. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 

Hanley, J. H. ......................................................... 20 

Hansley, P. L. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64, 73 

Harris, A. G. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 

Hatch, J. R. . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . .. . .. . . .. . . .. . . . . . . .. . . 21 

Hatcher, P. G. .......... .......................................... 3, 33 

Hendricks, J. D. ..................................................... 60 

Hercules, D. M. . .. . . . . . . . . . . . . . . . . . . . . . .. . .. . . . . . . . . . .. . . .. . .. . . .. . .. 36 

Herring, J. R. ........................................................ 24 

Hildebrand, R. T. .................................................... 25 

Hill, G. H. . . .. . . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . .. . . .. . .. . . . . . . .. . ... . . 33 

Hills, F. A. ............................................................ 17 

83 

Hinrichs, E. N. . .... .................... .............................. 27 

Hladky, F. R. ......................................................... 30 

Houghton, J. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 

Howell, D. G. ......................................................... 28 

Hudson, M. R. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 

Ingebritsen, S. E. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 

Isaacs, C. M. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 

Jackson, L. L. .. . . . . . .. . . . . . . . . . . .. . .. . . . . . . . . . ... . . . . . . . . . . . . . . . .. . . . 30 

Janik, C. J. ............................................................ 66 

Johnson, E. A. ........................................................ 31 

Jones, D. L. . . . . . . .. . . .. . .. . . . . . . . . . . . .. . .. . .. . . .. . .. . . .. .. . . . . . . . .. . .. 28 

Karachewski, J. A. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 

Karl, H. A. . . . . .. . . . . . . . . . . . . . . . . . . . . . .. . .. . .. . . .. . . .. . .. .. . . . . .. . .. . . . 13 

Kellogg, K. S. . . . . . . . .. . . . . . .. . . . . . .. . . .. . . . . . . . . . . . .. .. . .. . . .. .. . . . . .. 30 

Kent, B. H. . . . . .. . . . . . .. . . . . . . . . . . . . . . . . . .. . .. . . .. . . .. . . . . . . . . . . . . 31, 76 

Kenyon, N. H. ........................................................ 13 

Keys, W. S. .. .. ... .. .. .. .. .... .. .. .. . .. . .... .... ... . .. .. . .. .. .. .. .... .. 51 

Kirschbaum, M. ....................................................... 40 

Klitgord, K. D. .. .. .. .. .... .. .. .. .. .. .. .... .. .. .. .... .. .. ... .. . .. 33, 39 

Kotra, R. K. .. .. .. .. .. .. .. .. .. .. .. . .. . .. .. . .. .. .. .. . .. .. .. .. .. .. .. .. ... 33 

Krasnow, M. R. ........... ........................................... 36 

Krohn, K. K. . . .. . . . . . .. . . . . . . . . . . .. . . .. . .. . . .. . .. . . . . . . .. . . . . . .. . .. . .. 43 

Krystinik, K. B. . . . . . . . . .. . .. . . .. . .. . . . .. . .. . . . . . . .. . .. . . .. . .. . . .. . ... 34 

K venvolden, K. A. . . . . . . . . . . . .. . . . .. . .. . . . . . . . . . .. . . . . . .. . . .. . .. . .. . 11 

Lane, H. R. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . .... .. ... .. .... .. .. .. ... 21 

Law, B. E.............................................................. 35 

Lee, M. W. ............................................................ 36 

Leinbach, Jim . .. . . .. . . .. . .. . . . . . . . . . . .. . .. . . . . . . .. . .. .. . .. .. . . .. . .. . .. . .. 2 

Lickus, M. R. .. . . .. . . .. . .. . . . . . . . . . . .. . . . . . . . . . .. . .. .. . .. . .. . .. . . .. .. . 35 

Ludwig, K. R. . . .. . . . . . . . . . . . . . .. . .. . . . .. . . . . . . .. . . . . .. . . .. . . . . . .. . .. . 45 

Lyons, P. C. ................... ................................... 36, 53 

Magoon, L. B. .. .... .... .. .. . .. .. .. .... .. .. .... .. . .. . .. . .. .. .. 1, 6, 11 

Mariner, R. H. .. .. .. . .. .. .. .. .... .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .... ... 64 
Page 

Marlow, M. S. ........................................................ 12 

Masson, D. G. . . . . .. . . ... .. . . .. . . . . . . .. . .. . . . . . . ... ... . .. . .. . .. . .. . . . .. 13 

Mast, R. . . . . . . . . . .. . .. . . .. . . . . . .. . . . . . . .. . . .. . . . .. .. . . .. . .. . . .. . . . .. 27, 37 

McCulloch, D. S. ..................................................... 13 

McGregor, B. A. ..................................................... 39 

McLean, Hugh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 

Medlin, A. L. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 

M'Gonigle, J. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 

Miller, J. J. ............................................................ 41 

Miller, R. T .......................................................... -.. 41 

Minkin, J. A. ···························~-·················-·····- 9, 11,42 

Molenaar, C. M. ···········································~······ -6-, 43 

Molnia, C. L .............. -................. : .......... ,............ 31, 43 

Mooney, W. D ..... '....•............•.. : ......... ; .................. ~~ 50 

Moore; D. W ................. : ... : .. ·.................................. 48 

Morelli, J. J ... _ ......... -; ............................ ~ ................ .':. 36 

Morin, R. H ....... :: .......................... ,........................ 51 

Muffler, L.--J. P .......... ; ......... ;-.................... · ....... ;..... 79 

Nash, J. T .................. :........................................... 45 

N athenson;- Manuel ... .-.......................... -..... .• . . . . . . . . . . . . . 79 

Nokleberg, W. J •..... , ...................... .-................ -...... 50 

Northrop, H. R._ ........................................ .' ....... : -44, 73 

Nutt, C. J. ............ ................................................. 45 

O'Connor, J. T. ...... .......................... ... ................ 3, 46 

Oppenheimer, D. H. ..... ....... .................................... 47 

Oriel, S. S. .. .-........................ .' ......... _ ................. ~...... -48 

Otton, J. K ...................................................... :...... 49 

Page, R. A ............................................... ........ :..... 50 

Paillet, F. L ................................ -....... , ... _ ... ~ ....... ~~... 51 

Palacas, J. G. . ............ ;; ........................ _: .... : ... -..... ~... 5.3 

Palmer, C. A: ........................................... : ..... -._ .. - 36, 53 

Parrish, J. T ............................................. :............. 54 

Pawlewicz, M. J. .. ............................................... : ... - 35 

Perry, W. J.·, Jr ................................................ -..... 54 

Peterson, Fred .................................................... 17,- 44 

Pierce, F. W. .. . . .. . . . . . . . . . .. . .. . . . .. . . . . . .. . . . . . . . . . .. . .. . . .. . . . . . . . 31 

Pitman, J. K. . .. . . .. . . . . . . . . .. . . .. . . .. . . .. . . .. . . . . . . . . . .. . . . . . .. .. . . . . . 55 

Plafker, George . . . . . . . . . .. . .. . . .. . . . . . . . . . . .. . .. . .. . . . . . . . . . .. . . .. . .. . 50 

Poag, C. W ... , ........... u........................................... 57 

Pratt, L. M. ...................................................... 16, 57 

Priest, S. S. . . . .. . .. .. . . . . .. . . . . . . .. . . . . . .. . . . . . . .. . .. . .. . . . . . . . . . . . . . . 60 

--tru.s. GOVERNMENT PRINTING OFFICE:1986- 26011 

Page 

Reimer, G. M. ........................................................ 24 

Reynolds, R. L. . .................................................. .-.. 58 

Rice, D. D .............................................. '~...... .... 21, 80 

Ridgley, J. L. .. . . . .. . .. . . . . . . . . . . .. . . . . .. .. . .. . . .. . . . . . .. . . .. . .. . 76, 77 

Robison, L. C. .. . . .. . .. . . . .. . . . . . . . . . . . .. .. . .. . .. . . . . .. .. . .. . . . . . .. .. . 60 

Root, D. ................................................................. 27 

Sable, E. G. .. .. .. .. .. .. . .. . ... .. . .... . .. .. .. .. .. .. ... . .. .. ... .. .. . .. .. 59 

Sanford, R. F. ........................................................ 17 

Sass, J. H. ............................................................. 60 

Schenk, C. J. .......................................................... 61 

Schlee, J. S. ........................................................... 39 

Schmoker, J. W ................................................. 21, 61 

Sch6ll, D. W .............................................. ::........... 12 

Schuenemeyer, J. . . . . . . . . . . . . . . .. . . . .. . . . . . .. . . .. . .. . . .. . .. . .. . . . . .• . . 27 

Schultz, A. P. ......................................................... 61 

Senftle, F. E. .. . . .. . . . . . . . . . . . . .. . . . .. . . .. . .. . . .. . .. . . .. . . .. . .. . . . . .. . 62 

Shinn, E. A ........................................................... _. 19 

Sorey, M. L. ................. ......... ................................ 64 

Spiker, E. C. .. .. . .. . .. .. .... . .. ..... .. .. ... ... . .. .. .. ... .. .. . .. . .. 9, 33 

Spirakis, C. S. ........................................................ 64 

Stanley, .W. D. ........................................................ 16 

Stanton, R. W. . . .. . . . . . . .. . .. . . . .. . .. . . .. . .. . ... . . .. . . .. . . . . . . . . . 9, 71 

Stauber, D. A. . . . . . . . . . . . .. . . . . . . .. . .. . . .. . .. . . .. . . .. . .. . . .. . .. . . .. .. . 15 

Stewart, K~ C. . . . .. . . . . . . .. . . . . . . .. . .. . . .. . .. . . .. . . .. . .. . . .. . .. . . .. . . . 30 

Stricker, G. D. . .. .. .. .. . .. .. .. .... .. .. . .. .. ... ... ... .. .. .... . .. .. 59, 65 

Tailleur, 1.- L. .. .. .. .. . .. .. . .. .. .. . .. .. .. ..... .. .. .... .... . .. . .. .. .. .. . 21 

'True~ell; A. H. ...................................................... 66 

Turner-Peterson, C. E. ............................................ 67 

Tuttle, M. L. . . . . . . .. . . . . . . . . .. . . . .. . . .. . .. . . . . .. .. . .. . . .. . .. . . .. . . .. . . 68 

von Huene; R. E._ .. .. .. . .. .. .... . .... ... .... .... .. .. .. .. ... .. .. 41, 69 

Vuletich, A. ·K. .... ................................................... 57 

Wallace, R. H., Jr. ................................................. 69 

Wanty, R. B. .... ... .. .. .. . .. .. . .. . .. .. . .. .. .. .... . .. . .... ... . .. . .... .. 70 

Wa:i-wick·, P. D. ....................................................... 71 

Weaver,, J .. ;............................................................ 40 

Wenrich, K. J. .. . . . .. . . . . . . . . . . . . . . . . .. . .. . . . . .. .. . . . . . . . .. .. . .. . .. . . . 72 

Whelan, J. _F. . .. .. . . . . . . . .. . .. . . . .. . . . . . .. .. . . .. . . . . . . .. . . . . .. . .. .. . .. . . 9 

Whitney; Gene ................................................... 44, 73 

~~ti!~J,· ~: A.'.::::::::::::::::::::::::::::::::::::::::::::::::::::::: !! 

Zohdy, A. A._ R. ..................................................... 16