{ 

/ GEOLOGICAL SURVEY CIRCULAR 621 

U.S. Geological Survey 

Heavy Metals Program 

Progress Report 1968-

Field Studies 

U.S. Geological Survey 

Heavy Metals Program 

Progress Report 1968-

Field Studies 

---------------------------- uS .GEOLOGICAL SURVEY CIRCULAR 621 

-

Washington 1969 
United States Department of the Interior 

WALTER J. HICKEL, Secretary 

Geological Survey 

William T. Pecora, Director 

Free on application to the U.S. Geological Surlli!y, Washington, D.C. 20242 
CONTENTS 

Introduction ________________________ _ 

Organization _______ _ _______________ _ 

Projects underway ____________________ _ 

Analytical support_ ___________________ _ 

Geologic drilling _____________________ _ 

Geophysical support_ __________________ _ 

Airborne surveys ____________________ _ 

Ground surveys _____________________ _ 

1

:ijorehole investigations ____________ _ ___ -

i'ie\v facilities and equipment_ _________ --_-

Publications _ _ ______________________ _ 

Reports and maps on open file ____________ _ 

Studies on land ______________________ _ 

Alaska __________________________ _ 

Southern Alaska Range ______________ _ 

Central and eastern Alaska Range _______ _ B ttl s-Wis man sr n _______________ _ 

Eastern Brooks Range _______________ _ 

Eagle quadrangle and adjacent areas _____ _ 

E ter-Cleary mineral belt, Fairbanks 

region ________________________ _ 

Hyder district_ _______________ -----

Livengood district_ _________________ _ 

St. Lawrence Island _________________ _ 

Eastern Seward Peninsula ____________ _ 

Western Seward Peninsula ____________ _ 

Southeastern Alaska ________________ _ 

Talkeetna Mountains and central Alaska Range ________________________ _ 

Wrangell Mountains __ --------------- Yakutat region ____________________ -

Arizona ___________________ -_------

Lode and placer gold deposits, Mohave 

County _______________________ _ 

California ________________________ _ 

Geochemical studies at Bodie ___________ _ 

Mother Lode, Amador County __________ _ 

Tertiary gravels, Nevada City area, 

Sierra Nevada ________________ - - _ -

Page 

1 

1 

1 

1 

2 

2 

2 

2 

3 

3 

3 

5 

6 

6 

6 

6 

7 

7 

9 

9 

10 

10 

10 

11 

11 

12 

12 

12 

12 

12 

12 

13 

13 

Page 

Studies on land - Continued 

Colorado __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 14 

Gold in Castle Rock Conglomerate ________ 14 

Ore deposits of Chicago Basin ________ _ _ _ 14 

Geophysical stu die at Cripple Creek ______ 15 

Niobium and other elements, Gem Park 

Complex ________ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 15 

Silver and copper in McEJmo Canyon ______ 15 

Copper and silver in Precambrian rocks near Gunnison __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 16 

Geology of Hahns Peak and vicinity _______ 16 

Lookout Mountain area, eastern San 

Juan Mountains ________ _ _ _ _ _ _ _ _ _ _ _ 16 

orthwestern San Juan Mountains ________ 16 

Silver Cliff-Rosita district_ ____________ 16 

Georgia ____ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 17 

Dahlonega gold belL ___ -------------- 17 

M~ne ____________________________ 1 

Mineral deposits near We t Pembroke _____ _ 

Interpretation of geophysical logs, 

Burnt Nubble area _________________ 1 

Massachusetts _____________________ _ 

Gold in ores from ewburyport district_ ____ 1 

Montana __________________________ 1 

Gravity survey at eihart ____________ _ 

Virginia City district_ _______________ _ evada __________________________ _ 

Aurora district_ ___________________ _ 

arlin mine __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 19 

Copper Canyon _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 20 

Cortez-Mill Canyon-Buckhorn area_ _______ 20 

Gold Acres and Tenabo districts __________ 21 

Goldfield district_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 21 

Independence and Adobe Ranges __ _ _ _ _ _ _ _ 22 

Manhattan mineral belL ______________ 23 

Sheep Creek Range ________ _ _ _ _ _ _ _ _ _ _ 23 

Tuscarora Range ___________________ 23 

Virginia City district__ _______________ 23 

Ilf 
Studies on land-Continued 

New Hampshire _--------------------

Central and northern New Hampshire_-----

Ossipee Lake area_------------------

ew Mexico ____ ----------------- ---

Geochemical anomalies, Sierra Cuchillo --- --

North Carolina ___ -------------------

Burke, Caldwell, and Catawba Coun ties _----

Central North Carolina _--------------

Moore County __ ---------- -- -------

South Carolina ____ -- __ - - ---- -- ------

South Dakota ____ -------------------

Gold deposits in Precambrian rocks, 

northern Black Hills _______________ _ 

Ore deposits in Paleozoic rocks, northern Black Hills _______________ _ Uuh ____________________________ _ 

Silver Reef district_ _________ _______ _ 

Vermon L _________ - - - - - - - - - - - - - - - -

Virginia _________________________ _ 

Gossan Lead ___________ __________ _ 

Reconnaissance geochemical studies, 

southwest Virginia ________________ _ 

Virgilina district, Virginia and North 

Carolina _______________________ _ 

Wyoming ___ ______________________ _ 

Platinum metals, Medicine Bow 

Mountains ____________ _ _____ _ __ _ 

IV 

Page 

23 

23 

·24 

24 

24 

24 

24 

25 

25 

26 

26 

26 

27 

27 

27 

27 

27 

27 

2 

2 

2 

2 

Studies on land- ontinu d 

Wyoming- Continu d 

Quartzite conglomerates, northw st 

Wyoming ____ ------------------- Marine studies ______________ _ _______ _ 

Geology of the Bering and hukchi as, 

Alaska ___ _ ____________ ------

Studies around orne, ward P nin 

Bottom sampling in northern Bering a ___ _ 

Glacial studies, Bering a ____ _ _ _ ____ _ 

General geologic tudies, Bering a _____ _ 

Gulf of Alaska con tin ntal sh If __________ _ 

Heavy minerals, inner contin ntal sh If of 

W a hington _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

Geology of the Six River drainag , Oregon __ ___ _ __ __ _______________ _ 

Heavy mineral , Oregon continental h If ____ _ 

Geology and heavy min rals, contin ntal 

shelf, northern alifornia _____________ _ 

Mineralogy of contin ntal-sh If dim nts, 

southern California _________________ _ 

Heavy minerals, Middle Atlantic 

continental shelf ___________________ _ 

Miscellaneous studie _________________ _ 

Silver content of Foraminifera-b aring 

deep ocean sediments ______________ _ 

References cited _ _ ___________________ _ 

p'We 

29 

29 

29 

30 

30 

30 

31 

31 

31 

31 

32 

32 

33 

33 

33 

34 

~ 

( 

~ 

0 

d 

( 

v 
U.S. Geological Survey Heavy Metals Program 

Progress Report 1968-Field Studies 

INTRODUCTION 

The Heavy Metals program of the U.S. Geological Survey and the U.S. Bureau of Mines 

began in mid-1966 and thus at the end of calendar 

year 1968 was halfway through its third year. 

This progress report summarizes field studies 

1 carried out under the Geological Survey's part of 

3 the program during 1968. Topical studies for 

3 1968 are summarized in U.S. Geological Survey 

Circular 622. Background of the program and 

l3 results during 1966 and 1967 were reported in 

ll U.S. Geological Survey Circular 560 and will not 

be further discussed herein. 

ORGANIZATION 

In 1968, about 260 employees of the Geological 

Survey participated directly in the program. This 

number includes about 140 geologists, 30 chemists, 

and 10 geophysicists of the Geologic Division and 

eight professional employees (hydrologists and 

chemists) of the Water Resources Division. 

Another 135 or so were involved in analytical 

laboratories and publications. 

In addition to Geological Survey personnel, 

scientists from the university community took 

part in the program through research contracts 

and grants. In 1968, 19 contracts were in effect 

at 16 universities. Contract research in the 

marine field was carried out at the University of 

Alaska, University of California (Scripps Institution of Oceanography), Duke University, 

Louisiana State University, University of Oregon, 

Oregon State University, University of Southern 

California, Stanford University, Texas Agricultural and Mechanical University, and University 

of Washington; and land-based research was 

done at the University of Alaska University of 

California (Berkeley), Universit~ of Colorado, 

Colorado School of Mines Colorado State Uni- . ' vers1ty, University of Maryland, Oregon State 

1 

University, South Dakota School of Mines and 

Technology, and University of Texas. 

Contract research also was done by Tracerlab, 

Inc., a commercial research laboratory. 

PROJECTS UNDERW A¥ 

At the end of 1968, the program included 137 

projects in about 25 States. Land-based projects 

totaled 116; those in the marine field, 21. About 

96 projects were district- or region-oriented field 

studies and 41 were dominantly topically oriented 

field or laboratory studies. Geological Survey 

personnel accounted for 118 projects, and contract 

personnel for 19. Distribution of effort was 

approximately as follows: 

Percent 

Land-based district or regional studies ____ 43 

Topical field or laboratory studies _______ 25 

Marine studies _____ _ ______________ 14.5 

Contract research, marine ________ -- -- 6 

Contract research, land ______________ 2.5 

Other contracts _________ --------- =....1__ 

100.0 

ANALYTICAL SUPPORT 

Extensive chemical, spectrographic, and other 

analytical support was provided for the program. 

A substantial part of the analytical work was 

done in 15 to 20 truck-mounted mobile laboratories. 

In 1968, about 110,000 samples were processed. 

Analytical work consisted of 58,000 analyses for 

gold, 755 analyses of platinum metals (platinum, 

palladium, and rhodium), 21,000 analyses for 

mercury, and 72,000 analyses for other elements 

(antimony, arsenic, beryllium, bismuth, cadmium, 

cobalt, copper, lead, manganese, molybdenum, 

nickel, silver, tellurium, tungsten, uranium, 

vanadium, and zinc). Semiquantitative spectrographic analyses for 30 elements each were made 

on 55,000 samples, and 120 complete spectro-
graphic analyses were made to determine the 

trace element content of gold. Neutron-activation analyses for gold were made on 298 samples. 

A total of about 152,000 chemical determinations 

and 1,500,000 spectrographic determinations 

were made. 

GEOLOGI DRILLING 

Geologic core and noncore drilling to obtain 

information on the third dimension was done 

under contract in eight areas, as follows: 

1. Iron Canyon, 10 miles southwest of Battle 

Mountain, Nev. Two core-drill holes, started 

in April 1967, completed in June 1968. 

2. Tenabo-Gold Acres, east side of Shoshone 

Range 30 miles southeast of Battle Mountain, 

Nev. Five core-drill holes, started in July 

1967, completed in July 1968. 

3. Roubaix and Rochford districts, northern 

Black Hills, S. Dak. Two core-drill holes, 

started in July, completed in September. 

4. Ragged Top area, northern Black Hills, S. Dak. 

Two core-drill holes, started in July, completed in September. 

5. Goldfield district, Nev. Two core-drill holes, 

started in July, completed in December. 

6. Virginia City (Comstock Lode) district, Nev. 

Five core-drill holes, started in August, 

drilling still in progress at year's end. 

7. San Juan Ridge, Nevada County, Calif. Four 

rotary-drill holes and some core drilling, 

started in July, drilling still in progress at 

year's end. 

8. Badger Hill-North Columbia area, Nevada 

County, Calif. Six churn-drill holes, started 

in September, completed in December. 

GEOPHY ICAL S PPORT 

A wide variety of geophysical support was 

provided to various projects. These geophysical 

investigations are summarized here; details on 

individual projects are included in the project 

descriptions. 

AlRBOR E SURVEYS 

Aeromagnetic surveys with flight lines spaced 

1 mile apart were done in the Barker and Neihart 

quadrangles southeast of Great Falls in central 

Montana (420 square miles), in the Great Salt 

Lake Desert between Bingham and Wendover in 

Utah (6,480 sq mi), in the Virgin Basin south of 

Lake Mead in northwestern Arizona (2,200 sq 

mi), in the Crown .King area of the Bradshaw 

2 

Mountains south of Prescott in central Arizona 

(1,165 sq mi), in the Y ellowpine district of west· 

central Idaho (1,300 sq mi), and in the San Juan 

Mountains and the Cripple Creek district of 

south-central Colorado (about 8,200 sq mi). A 

detailed aeromagnetic map with flight lines a 

quarter of a mile apart was made of the volcanic 

basin of the Cripple Creek mining district in 

central Colorado, and a similar detailed low-lev~ 

study was made of the Wickes mi~ing district 

between Helena and Butte in western Montana 

Aeromagnetic surveys with 1-mile flight-line 

spacing were made under contract in northeastern 

Idaho and western Montana, an area of about 

8,500 sq mi that includes the Coeur d'Alene 

mining district of Idaho and extends north Ui 

Libby, Mont., east nearly to Kalispell, Mont., and 

south to Superior, Mont.; in several places in 

Alaska with a total extent of about 7,300 sq rni 

and including areas on, north, and east of Seward 

Peninsula, in the southern Alaska Range, and a 

Nixon Forks north of McGrath in southwesterr 

Alaska; and on and offshore from the coast of 

Oregon over an area of about 18,500 sq mi. 

Electromagnetic surveys were made in th! 

Burnt Nubble area northeast of The Forks, Maine 

and the Catheart Mountain area east of Jack· 

man, Maine; and radioactivity surveys cov ri ~ 

about 1500 sq mi were made in Alaska. 

Aeromagnetic maps of 39 15-minute quad 

rangles, the Virginia City quadrangle, and part 

of three other quadrangles in Nevada have be6 

placed on open file. Other aeromagnetic rna~ 

completed are of the Grass Valley-Nevada Ci 

and northern Mother Lode areas, California, an 

the Central City area, Colorado. Some data all 

now available on combined aeromagnetic, electn· 

magnetic, and gamma-ray surveys of the Hail 

and Brewer mine area in north-central Soutl 

Carolina, the Eastport-Calais area in easternm~ 

Maine, and the Grass Valley and Mother ~ 

areas in California. 

GROU 0 SURVEYS 

Ground-based electromagnetic (EM), indue! 

polarization (IP), magnetic, seismic, gravit 

gamma-ray, and very low frequency (VLI 

studies were made for many projects. Stu 

areas included the Chulitna district (EM, IP) 

south-central Alaska; the Nevada City an 

(seismic, gravity, EM, IP, resistivity) in Ca 

fornia; the Ouray-Silverton district (gamma-1'1 
IP, EM, VLF), Cripple Creek district (gravity, 

magnetic, and gamma-ray) and Silver Cliff 

district (gravity, seismic) in Colorado; the Barker 

and Neihart districts (gravity) and Wickes district 

(magnetic) in Montana; Swales Mountain and 

Lone Mountain in Elko County (magnetic, resistivity), Snowstorm mine in the Sheep Creek 

Range north of Battle Mountain (IP), the Midas 

and Ivanhoe districts in Elko County (magnetic), 

and the Tenabo and Cortez districts in Land~r 

County (gravity), all in Nevada; and the Gros 

Ventre River valley (resistivity) in Wyoming. 

BOREHOLE INVESTIGATIO S 

Development and testing of borehole instruments continued, and field tests were made in 

the Nevada City area, California; the Burnt 

ubble area near The Forks and Catheart Mountain east of Jackman, both in Maine; and Cornwall Knob near Virginia City, Iron Canyon south 

of Battle Mountain, and Tenabo and Buckhorn 

districts southeast of Battle Mountain, all in 

Nevada. Methods used included gamma-ray, 

magnetic susceptibility, resistivity, self-potential, 

IP, and temperature. 

NEW FACILITIES AND EQUIPMENT 

To extend and improve laborat ry and fi eld 

support for the program, new mineralogical 

laboratories were completed at field centers in 

Denver, Colo., and Menlo Park, Calif., and considerable new equipment was acquired. A mass 

spectrometer for sulfur isotope studies, an electron 

microprobe, and an X-ray diffractometer were 

installed at the Denver center. 

Analytical laboratories of the Field Services 

Section were consolidated at the Mcintyre Street 

site, in Denver, Colo., and capacity much increased through the lease of two additional 

buildings. Two new fire-assay furnaces are 

planned for this facility. 

PUBLICATIONS 

Publications resulting from or pertaining to 

the Heavy Metals program during 1968 included 

29 Geological Survey Circulars, seven Geological 

, Survey Professional Papers or Bulletins, nine 

articles in Geological Survey research 1968, three 

Geological Survey maps, and nine articles in 

technical journals. Instructions for ordering 

Geological Survey publications appear at end of 

l r.eport. The following reports were published 

(m approximate chronological order): 

3 

Professional Paper 594- F, Hydraulic equivalence 

of grains of quartz and heavier minerals, and 

implications for the study of placers, by H. F. 

Tourtelot, 13 p. Price, 20 cents. 

Circular 553, Silver in veins of hypogene manganese oxides, by D. F. Hewett, 9 p. 

Bulletin 1251- I, Devonian and Mississippian rocks 

and the date of the Roberts Mountains thrust 

in the Carlin-Pinyon Range area, Nevada, by 

J. F. Smith, Jr., and K. B. Ketner, 18 p. Price, 

15 cents. 

Map MF -301, Map of southeastern Maine showing heavy metals in stream sediments, by E. 

V. Post, W. L. Lehmbeck, W. H. Dennen, and 

G. A. Nowlan. Price, 50 cents. 

Bulletin 1242-F, Geochemical cycle of selected 

trace elements in the tin-tungsten-beryllium 

district, western Seward Peninsula, Alaska-a 

reconnaissance study, by C. L. Sainsbury, J. C. 

Hamilton, and Claude Huffman, Jr., 42 p. 

Price, 75 cents. 

Circular 557, Lead, copper, molybdenum, and zinc 

anomalies south of the Summitville district, Rio 

Grande County, Colorado, by W. N. Sharp and 

J. L. Gualtieri, 7 p. 

Circular 560, U.S. Geological Survey Heavy 

Metal Pr gram Progress Report, 1966 and 

1967, 24 p. 

Determination of palladium, platinum, and 

rhodium by fire-assay-emission spectrography, 

by Joseph Haffty and L. B. Riley: Talanta, v. 

15, no. 1, p. 111- 117. 

Spatial relation of metal-mining districts to 

Tertiary volcanic centers in Nevada, by J.P. 

Albers and F. J. Kleinhampl: Am. Inst. Mining 

Metall. Petroleum Engineers mtg., New York, 

N.Y., February 1968; informal distrib. 

Professional Paper 594- C, Silver-rich disseminated sulfides from a tungsten-bearing quartz 

lode, Big Creek district, central Idaho, by B. F. 

Leonard, C. W. Mead, and Nancy Conklin, 24 p., 

4 pl. Price, 35 cents. 

Map. I-530, Regional geologic map of the Selawik 

and southeastern Baird Mountains quadrangle, 

Alaska, by W. W. Patton, Jr., and T. P. Miller. 

Price, $1.00. 

Circular 559, Lead, zinc, and silver deposits at 

Bowser Creek, McGrath A-2 quadrangle, 

Alaska, by B. L. Reed and R. L. Elliott, 17 p. 

Professional Paper 600-B, Geological Survey 

research 1968. Price, $2.00: 

Determination of palladium and platinum in 
rocks, by F. S. Grimaldi and M. M. Schnepfe, 

p. B99-B103. 

Concentration and minor element association 

·of gold in ore-related jasperoid samples, 

by T. G. Lovering, H. W. Lakin, and A. E. 

Hubert, p. B112-B114. 

Rapid analysis for gold in geologic materials, 

by C. E. Thompson, H. M. Nakagawa, and 

G. H. VanSickle, p. B130- B132. 

Circular 561, An atomic-absorption method for 

the determination of gold in large samples of 

geologic material, by G. H. VanSickle and H. 

W. Lakin, 4 p. 

Circular 562, Utilization of humus-rich forest soil 

(mull) in geochemical exploration for gold, by 

G. C. Curtin, H. W. Lakin, G. J. Neuerburg, 

and A. E. Hubert, 11 p. 

Circular 563, Favorable areas for prospecting 

adjacent to the Roberts Mountains thrust in 

southern Lander County, Nevada, by J. H. 

Stewart and E. H. McKee, 13 p. 

Circular 564, Occurrences of gold and other 

metals in the upper Chulitna district, Alaska, 

by C. C. Hawley and A. L. Clark, 21 p. 

Bulletin 1278-A, Metal absorption by Equisetum 

(horsetail), by H. L. Cannon, H. T. Shacklette, 

and Harry Bastron, 21 p. Price 15 cents. 

Circular 565, Cassiterite in gold placers at Humboldt Creek, Serpentine-Kougarok area, Seward 

Peninsula, Alaska, by C. L. Sainsbury, Reuben 

Kachadoorian, T. E. Smith, and W. C. Todd, 

7 p. 

Circular 566, Tertiary gold-bearing channel 

gravel in northern Nevada County, California, 

by D. W. Peterson, W. E. Yeend, H. W. Oliver, 

and R. E. Mattick, 22 p. 

Circular 569, Geochemical anomalies and metalliferous deposits between Windy Fork and Post 

River, southern Alaska Range, by B. L. Reed 

and R. L. Elliott, 22 p. 

Circular 570, Suggested areas for prospecting in 

the central Koyokuk River region, Alaska, by 

T. P. Miller and 0. J. Ferrians, Jr., 12 p. 

Circular 587, Gold distribution in surface sediments on the continental shelf off southern 

Oregon: a preliminary report, by H. E. Clifton, 

5 p. 

Evidence for possible placer accumulations on the 

southern Oregon continental shelf, by L. D. 

Kulm, D. F. Heinrichs, R. M. Buehrig, and D. 

M. Chambers: The Ore Bin, v. 30, p. 81-104. 

Circular 588, Geochemical anomalies in the Swales 

4 

Mountain area, Elko County, Nevada, by K. B. 

Ketner, J. G. Evans, and T. D. Hessin, 13 p. 

Circular 589, Distribution of gold, silver, and 

other metals near Gold Acres and Tenabo J 

Lander County, Nevada, by C. T. Wrucke, T. J. 

Armbrustmacher, and T. D. Hessin, 19 p. 

Fluorometric determination of gold in rocks with 

Rhodamine B, by John Marinenko and Irving 

May: Anal. Chemistry, v. 40, p. 1137- 1139. 

Determination of gold in rocks by neutron activation analysis using fire-assay preconcentration, 

by F. 0. Simon and H. T. Millard, Jr.: Anal. 

Chemistry, v. 40, p. 1150- 1152. 

Map I- 554, Regional geologic map of the Shungnak and southern part of the Ambler River 

quadrangles, Alaska, by W. W. Patton, Jr., 

T. P. Miller, and I. L. Tailleur. Price, $1.00. 

Circular 590, Potential for lode deposits in the 

Livengood gold placer district, east-central 

Alaska, by R. L. Foster, 18 p. 

Use of mercurous chloride to recover trace 

amounts of gold from waters, by E. A. Jenne, 

T. T. Chao, and L. M. Heppting: Econ. Geology, 

v. 63, p. 420-21. 

Geologic environment of gold deposits in Nevada 

[abs.], by R. J. Roberts, K. B. Ketner, and 

A. S. Radtke, 1967: Inst. Mining and Metal· 

lurgy [London] Trans., v. 76, sec. B, Bull. 732, 

p. B228-B229. 

Coagulation of humic colloids by metal ions, by 

H. Ling Ong and R. E. Bisque: Soil ci., v. 106, 

no. 3, p. 220-224. 

Circular 591, Direct-current arc and alternating· 

current spark emission spectrographic field 

methods for the semiquantitative analysis of 

geologic materials, by D. J. Grimes and A. P. 

Marranzino, 6 p. 

Circular 592, Interpreting pan-concentrate anal· 

yses of stream sediments in geochemical ex· 

ploration for gold, by R. P. Fischer and F. 

Fisher, 9 p. 

Professional Paper 600- C, Geological Survey 

research 1968. Price, $2.25: 

Geology of the Klamath River delta, 

California, by G. W. Moore and E. A 

Silver, p. C144- Ci48. 

Determination of gold, platinum, and pal· 

ladium by a combined fire-assay, ion· 

exchange, and spectrochemical techniqu 

by P. R. Barnett, D. L. Skinner, and Claudf 

Huffman, Jr., p. C161- C163. 

Circular 593, Distribution of gold and some bast · 
metals in the Slana area, eastern Alaska Range, 

by D. H. Richter and . A. Matson, Jr., 20 p. 

Circular 595, Geochemical and geophysical anomalies in the western part of the Sheep Creek 

Range, Lander County, Nevada, by G. B. Gott 

and C. J. Zablocki, 17 p. 

Circular 596, Preliminary results of geological, 

geochemical, and geophysical studies in part of 

the Virginia City quadrangle, Nevada, by D. H. 

Whitebread and D. B. Hoover, 20 p. 

Circular 597, Distribution of beryllium, tin, and 

tungsten in the Lake George area, Colorado, 

by C. C. Hawley and W. R. Griffitts, 18 p. 

Circular 599, The determination of gold in geologic materials by neutron-activation analysis 

using fire assay for the radiochemical separations, by J. J. Rowe and F. 0. Simon, 4 p. 

Professional Paper 612, Geology of niobium and 

tantalum, by R. L. Parker and Michael 

Fleischer. Price, 50 cents. 

Simultaneous determination of tantalum and 

hafnium in silicates by neutron activation 

analysis, by L. P. Greenland: Anal. Chim. Acta., 

V. 42, p. 365-370. 

Geology of lode tin deposits, by C. L. Sainsbury 

and J. C. Hamilton, in A technical conference 

on tin, London, 1967: London, Internat. Tin 

Council, v. 1, p. 314-349. 

Tin and beryllium deposits of the central York 

Mountains, western Seward Penin ula, Ala ka 

by . L. Sainsbury, in Ore deposit of the 

United tates 1933- 1967: New York, AIMMPE 

Inc., v. 2, p. 1555-1572. 

Profe ional Paper 610, Principal gold-producing 

districts of the United States, by A. H. 

Ko chmann and M. H. Bergendahl, 2 3 p. 

Price, $4. 75. 

Circular 600, Geochemical evidence for pos ible 

concealed mineral deposits near the Monticello 

Box, northern ierra Cuchillo, ocorro County, 

ew Mexico, by W. R. Griffitts and H. V. 

Alminas, 13 p. 

Circular 603, Gold in meteorites and in the 

earth's crust, by R. S. Jones, 4 p. 

ircular 606, Anomalous concentrations of gold, 

silver, and other metals in the Mill Canyon 

area, Cortez quadrangle, Eureka and Lander 

Counties, Nevada, by J. E. Elliott and J. D. 

Wells, 20 p. 

ircular 604, Distribution of gold, copper and 

some other metals in the McCarthy B- 4 and 

I· B-5 quadrangles, Alaska, by E. M. MacKevett, 

5 

Jr., and J. G. Smith, 25 p. 

Circular 605, Gold distribution on the sea floor 

off the Klamath Mountains, California, by 

G. W. Moore and E. A. Silver, 9 p. 

Circular 607, Platinum and associated elements 

at the New Rambler mine and vicinity, Albany 

and Carbon Counties, Wyoming, by P. K. 

Theobald, Jr., and C. E. Thompson, 14 p. 

Professional Paper 600- D, Geological Survey 

research 1968. Price, $3.25: 

Adsorption of traces of silver on sample 

containers, by T. T. Chao, E. A. Jenne, and 

L. M. Heppting, p. D13-D15. 

Prevention of adsorption of trace amounts 

of gold by containers, by T. T. Chao, E. A. 

Jenne, and L. M. Heppting, p. D16-D19. 

Residual enrichment and supergene migration of gold, southeastern United 

States, by A. R. Kinkel, Jr., and F. G. 

Lesure, p. D174-D178. 

Determination of rhodium in rocks, by M. M. 

Schnepfe and F. S. Grimaldi, p. D210- D213. 

REPORTS AND MAPS ON OPEN FILE 

The following reports and maps were placed 

on open file during 1968. 

REPORT 

Gold gradients and anomalies in the Pedro-Cleary 

Summit area, Fairbanks district, Alaska, by 

R. B. Forbes, H. D. Pilkington, and D. B. 

Hawkins. 

GEOLOGIC MAP 

Geochemical reconnaissance maps of granitic 

rocks, Coleen and Table Mountain quadrangles, 

Alaska, by W. R. Brosge and H. N. Reiser. 

Reconnaissance geologic map of the Tanacross 

quadrangle, Alaska, by H. L. Foster. 

AEROMAGNETI MAPS 

evada: aeromagnetic maps covering all or parts 

of the following areas: 

Elko County: Bull Run, Hat Peak, Jarbidge, 

Midas, Mountain City, Mount Velma, North 

Fork, Norths Ranch, Owyhee, Rowland, 

Tuscarora, Wild Horse, and Wilson Reservoir quadrangles. 

Eureka and White Pine Counties: Eureka 

region. 

Humboldt County: Golconda quadrangle. 

Lander County: Battle Mountain quadrangle 

and Austin region. 
Lander and Eureka ounties: Dunphy 

quadrangle. 

Pershing County: nionville region. 

South Carolina: airborne electromagnetic and 

total intensity magnetic profiles in the vicinity 

of the Haile, Brewer, and Blackmon mines, 

Lancaster, Chesterfield, and Kershaw Countie . 

ST DIE ON LA D 

Abbreviations commonly used are: 

ppm= parts per million (1 ppm= 0.0001 percent, 

or about 0.03 oz per ton; for gold at 

$35.00 per oz 1 ppm equals about $1.00 

per ton) 

ppb=parts per billion (1 ppb=0.0000001 

percent) 

Analytical data for gold, platinum metals, and 

silver are usually given in parts per million or 

parts per billion. Results are frequently reported 

as "less than" a certain amount, this amount 

being the limit of detection of the analytical 

method employed. Such a result means that 

the element was not detected and, if present at 

all, occurs only in an amount below the detection 

limit. 

ALA KA 

The second full fi ld eason under the program 

was completed in Alaska in the summer of 196 . 

The Alaska program comprised 16 projects and a 

research contract with the Univer ity of Alaska. 

Work was done in selected areas of southeast, 

central, and southwe t Ala ka and on and 

east of Seward Peninsula. About 25 Geological 

Survey scientists took part, as well as three 

professors from the University of Alaska. Nearly 

32,000 samples were analyzed during the year, 

many of these in a mobile laboratory stationed 

at Anchorage. Publications on Alaskan studies 

included one bulletin, eight circulars, two maps, 

one press release, and two outside publications. 

Southern Alaska Range 

Lead-silver-zinc occurrences between Windy 

Fork and Post River in the southern Alaska 

Range south of Farewell were reported in U.S. 

Geological Survey Circulars 559 and 569. Replacement deposits in limestone are associated 

with felsic breccia pipes. As a result of considerable exploration activity, additional deposits 

were discovered in 1968. 

6 

Ma sive fine-grained copper-silver-zinc sulfide 

deposits were observed in 1967 in the Talkeetna 

- 6 quadrangle 2 mil s north of Shellabarger 

Pas in the Alaska Range. Th deposits were 

mapped and sampled in more detail in 1968. 

The deposits are of two gen ral types, bedding 

replacement of calcareous units in a sequence 

· of chert and argillitic limestone that is cut by 

diabasic dik s, and fractur fillings in chert. The 

dominant min rals are pyrite, chalcopyrite, 

sphalerite, ar enopyrite, and ulfosalts. The 

largest body exposed is slightly more than 100 

feet long and at least 17 feet thick. Massive 

ulfides crop out 1000 f t south and also 00 

feet we t of the main showings. Analyses of 

samples how 0.5 to 5 perc nt copper and zinc, and 

0.2 to 9 ounces of silver per ton. These deposits 

are of a new type and occur in a different geologic setting than tho e south of Farewell. 

Several alteration zone and occurrences of 

float containing lead, ilver, zinc, and molybdenum were noted during reconnaissance mapping 

and ampling of plutonic rock between Two 

Lake and Farewell. 

A eries of biotite granites containing anomalous amounts of tin appears to define a new 

tin belt in the central Ala ka Range. Additional 

mapping and analyse are necessary to further 

define this belt. 

A pilot study using soil sampling in th Nixon 

Fork gold lode district may have defined a new 

ore bod or given an excellent xample of an 

inten e gold anomaly displaced by oil cr p from 

a previou ly worked deposit. Thi pilot study 

should provide guidelines for g ochemical ex· 

ploration in thi part of Ala ka. An aeromagnetic survey of the Nixon Fork di trict 

indicates the presence of covered intru iv bodies 

which cut limestone and a thru t fault. Ina 

much a all the known ore bodies in thi di tric 

are contact metamorphic deposits in limestone 

along the contact of quartz monzonite stocks. 

these magnetic anomalies may be of economic 

significance. (B. L. Reed, R. L. Elliott, ano 

G. D. Eberlein, Menlo P3;_rk, Calif.) 

Central and Eastern Alaska Range 

Geochemical in vestigations in the Slana areJ 

of the eastern Alaska Range, made in cooperatiot 

with the Alaska Division of Mines and Geology. 

were reported in U.S. Geological urvey Circulai 

593. This study suggests that ead-zinc-molybd~ 
num-silver mineralization is associated with a 

large zoned quartz monzonite-granodiorite 

pluton, the Ahtell Creek pluton, whereas goldcopper mineralization is associated with small 

diorite-quartz diorite intrusives. Preliminary 

drilling of an altered area in the Ahtell Creek 

pluton has revealed significant amounts of 

molybdenite. Further exploration is planned 

by industry. 

Reconnaissance geologic mapping and geochemical studies have been completed in the 

Nabesna B- 4 and A-3 quadrangles with some 

overlap into the N'abesna A-2, A-5, B-3, B-5 and 

C-5 quadrangles. All investigations were south 

of the Denali lineament in an area underlain by 

upper Paleozoic and Mesozoic sedimentary and 

volcanic rocks. 

A thick unit of amygdaloidal basalt flows of 

Permian or Triassic age warrants attention as a 

potential source of copper. This unit, which is 

as much as 5000 feet thick, has now been traced 

from the head of the Chistochina River, in the 

Mount Hayes quadrangle, southeast over 140 

miles to the Canadian border. ative copper 

and occasionally copper sulfides occur in minor 

amounts throughout the flows in amygdules, 

scoriaceous flow tops and bottoms, and fractures 

and local shear zones. Mineralogically and 

petrographically the flows appear similar to the 

Precambrian basalts of the Upper Peninsula of 

Michigan and to the Nikolai Greenstone of 

Tria ic age exposed along the south flank of 

the Wrangell Mountain in Ala ka. Amygdule 

minerals consist chiefly of chlorite, cal cit , quartz, 

and epidote with les er amounts of pumpellyite, 

prehnite, heulandite, analcime, and natrolite. 

Preliminary pota sium-argon dates indicate 

emplacement ages of Early Cretaceous for some 

diorite, quartz diorite, and quartz monzonite 

tocks. Field evidence suggests an even younger 

age for orne of the larger complex granodiorite 

intrusives. The granodiorite intrusives appear 

to be more economically significant than the 

smaller less alkalic stocks and plutons. The 

"Bond Creek" batholith in the Nabesna area is 

host for at least one low-grade porphyry copper 

deposit and a number of contact-metamorphic 

base-metal depo its. 

The character and distribution of placer gold 

in the Chistochina district indicate that the 

so urce of the gold is a highly weathered conglomerate, probably of pre-Tertiary age. Signif7 

icant residual concentrations of gold are present 

locally in the conglomerate on upland surfaces. 

Placer gold has been found in Tertiary conglomerate in the elchina district in the western 

part of the Talkeetna Mountains. These rocks 

had been considered as a possible source of 

placer gold in the district but heretofore no gold 

has been found in them. This finding will aid 

in locating areas most likely to contain other 

gold placer deposits. (D. H. Richter, Anchorage, 

Alaska, and 0. J. Ferrians, Menlo Park, Calif.) 

Bettles-Wiseman Area 

Geochemical studies along the upper Kanuti 

River, a tributary of the Koyokuk River south 

of Bettles in north-central Alaska, led to the 

discovery of a small disseminated deposit of lead, 

silver, and zinc. Geochemical sampling along a 

tributary of the Kanuti revealed anomalous concentrations of tin which appear to be related to 

nearby biotite granites, some of which run as 

high as 70 ppm tin in bulk samples. 

A heretofore unknown belt of ultramafic and 

mafic rocks has been mapped from Caribou 

Mountain, southeast of Bettles, at least 65 miles 

southwestward along the margin of the YukonKoyukuk basin. The ultramafic rocks contain 

2,000-5,000 ppm nickel. The possibility of residual concentration, particularly beneath overlapping nonmarine Cretaceous sediments, warrants 

further investigation. 

mall bench placers on the South Fork of the 

Koyukuk River south of Wiseman appear to 

have their source in quartz veins in a belt of 

schist exposed along the south side of the river. 

Reconnaissance mapping and preliminary results 

of geochemical sampling suggest that these 

deposits mark the southern limit of the WisemanChandalar gold district. (W. W. Patton, Jr., 

Menlo Park, Calif.) 

Study of electrical properties of schist bedrock 

along the Middle Fork of the Koyukuk River 

shows that the conductivity of the schist is similar 

to that of the overlying gravels. Study of 

resistivity data indicates a depth to bedrock of 

only about 60 feet on Porcupine Creek, well 

within reach of modern gold dredges. Bedrock 

depth along the Koyukuk at Wiseman is about 

250 feet. (L.A. Anderson, Denver, Colo.) 

Eastern Brooks Range 

Reconnaissance stream sediment sampling in 
the Chandalar quadrangle and the eastern part 

of the Wiseman quadrangle on the south slope 

of the Brooks Range in eastern Alaska has 

revealed only two conspicuous regional anomalies; these coincide with the two known gold 

mining districts near Wiseman and Chandalar. 

A third anomalous area is suggested by the 

clustering of samples with anomalous amounts 

of silver in a zone along the contact between 

granite and carbonate rock north of the mining 

districts. The concentration of silver is not high, 

but silver is known to occur in galena at one 

prospect and as nuggets in a stream placer in the 

area. 

The Old Crow granite pluton, of Carboniferous 

age , in the Coleen quadrangle, easternmost 

Alaska, may be in part a tin granite. Tin has 

not been detected in stream sediments derived 

from Mesozoic granites farther west, but does 

occur with beryllium in sediments of two streams 

near the center of the Carboniferous granite at 

the Canadian boundary. Tin also occurs in 

rhyolite associated with this granite. Analyses 

of the granite are to be made. (W. P. Brosge, 

Menlo Park, Calif.) 

Eagle Quadrangle and Adjacent Areas 

During geologic reconnaissance of the Eagle 

quadrangle, eastern most central Alaska, an 

asbestos occurrence was observed in 1968 and 

reported in U.S. Geological Survey Circular 611, 

(published in 1969). The exposed part of the 

deposit consists of large joint blocks of serpentine 

which are cut by closely spaced subparallel veins, 

mostly about a quarter of an inch thick, of 

cross-fiber chrysotile asbestos. The asbestos 

appears to be of commercial quality, but the total 

quantity is unknown. 

Geochemical sampling and reconnaissance 

geologic mapping along a portion of the Tintina 

fa ult zone in the Seventymile River area indicates a zone of mineralization at least 30 miles 

long and up to 15 miles wide. Gold mineralization appears to be associated with a belt of 

serpentinized ultramafic rocks in the zone of 

faulting, and placer gold in part of the area, 

particularly Flume Creek and vicinity, appears 

to be derived from rocks in the fault zone. At 

Flume Creek, lode gold and arsenopyrite occur 

in quartz-carbonate rock and quartz veins in 

ultramafic and mafic rock. 

Geochemical sampling and reconnaissance 

8 

geologic mapping in the Fortymile River area 

indicate a previously unsuspected possible 

anomaly on Alder Creek and on Champion 

Creek. Near Champion ·Creek a lead-zinc vein 

of unknown size was located. Anomalies found 

in American Creek, North Fork, Gold Run area, 

Montana Creek area, and Ketchumstuk area 

indicate some further investigation may be 

warranted, although placer mining and (or) prospecting has already been done there. Geochemical sampling did not indicate mineralization 

in addition to known prospects in the My CreekOur Creek area. (H. L. Foster and S. H. B. Clark, 

Menlo Park, Calif.) 

Est er-Cieary Mineral Belt, Fairbanks Region 

The Ester-Cleary mineral belt, an area of some 

800 sq mi lying immediately northwest, north 

and northeast of Fairbanks, is being studied 

under a research contract with the University 

of Alaska. 

The area is one of mica schist and micaceous 

quartzite intruded by quartz monzonite plutons 

and dikes and cut by auriferous quartz veins. 

The gold and sulfide lode deposits are chiefly 

localized along domed portions of the Cleary 

anticline and in the southeast quadrant of Ester 

Dome. They seem to be genetically related to 

quartz monzonite intrusive in favorable structural settings. 

Gold anomalies have been found in fracture 

and shear zones, as much as 40 feet in width, in 

quartz monzonite, quartz diorite, and crystalline 

schists. These anomalies are commonly surrounded by haloes with traces of antimony and 

(or) arsenic. Geochemical sampling on the 

southeast slopes of Ester Dome has found several 

wide hydrothermal alteration zones in schists. 

These zones contain anomalous amounts of gold, 

and at least one high-grade gold-quartz vein has 

been found. In the Cleary Summit area, 16 

samples across an alteration zone 20 feet wide 

contained as much as 17 ppm gold, and half of 

these samples had 0.5 ppm or more. Sampling 

of discordant quartz veins beyond the usual 

limits of the Fairbanks lode belt shows that the 

zone of gold enrichment is much broader than 

previously recognized. 

Geochemical and structural data show that 

fracture- and shear-zones along the axial zone 

of the Cleary anticline cut all the major rock 
units and that heavy metals mineralization is 

accompanied by silicification and hydrothermal 

alteration along these zones. Some of the more 

persistent zones in the quartz diorite and crystalline schists may be of potential economic interest. 

Approximately 40 miles of magnetometer, 

gravity, resistivity, and induced polarization 

traverses were made by members of the Regional 

Geophysics Branch. About 370 shallow holes 

were drilled with a truck-mounted mobile drill 

for bedrock mapping and geochemical analysis, 

and about 500 samples were taken from these 

holes. Several hundred geochemical samples 

were taken from surface exposures, rubble-soil, 

prospect trenches, and streams. Several gold 

anomalies (as much as 200 ppm) were found in 

samples from auger holes on the Ester Dome 

road. 

Geochemical sampling in and near the Gilmore 

Dome granite-monzonite pluton showed some 

slightly anomalous metal values, but none of the 

anomalies appear to indicate significant zones of 

mineralization. 

An interesting problem being studied by 

several Heavy Metals projects is the distribution 

of gold in wallrocks of lode deposits-that is, are 

any high grade or bonanza precious metal deposits 

bordered by or enclosed in envelopes of low-grade 

disseminated ore? Field and laboratory investigation of this problem in the Ester-Cleary region 

shows that gold gradients do exist in wallrocks 

adjacent to veins. Gold assays as high as 1.1 

ppm were found as much as 5 feet from a vein, 

and assays of > 1 ppm, as far as 9 feet from a 

vein. At least four veins were found at which 

gold contents of 0.5 ppm or more were found in 

wallrocks several feet from the vein. 

A detailed structure section across the EsterCleary mineralized belt with reasonably good 

geological control and supporting geophysical 

data gives new information on the probable 

thrust fault in the Cleary anticline, on the relationship of two rock units of different metamorphic facies and structural habit, and on the 

structural and facies control of the lode deposits. 

Gravity and magnetometer traverses seem to 

confirm the other geologic field evidence for a 

fault and an eclogitic rock unit in the Cleary 

anticline. The eclogitic rocks are apparently 

within the more complex lower plate, which is 

mostly barren of mineral deposits. (R. M. Chap9 

man, R. B. Forbes, H. D. Pilkington, and D. B. 

Hawkins, Fairbanks, Alaska) 

Hyder District 

Geologic and geochemical studies are being 

made in the Bradfield Canal A- 1 and Ketchikan 

D-1 quadrangles of the Hyder district northeast 

of Ketchikan in southeasternmost Alaska. 

The Bradfield Canal A- 1 quadrangle has been 

mapped in as much detail as vegetation and snow 

cover will allow, and the Ketchikan D-1 quadrange, underlain almost wholly by granitic rock 

and glacial deposits, in slightly less detail. The 

geology along much of the Portland Canal, which 

cuts through the Coast Range batholith, was 

mapped in rapid reconnaissance fashion in conjunction with a gravity survey of southeastern 

Alaska by the Branch of Regional Geophysics. 

Granitic rock samples for potassium-argon and 

fission-track dating were collected. In a general 

way, the average composition of the Coast Range 

batholith changes from diorite and granodiorite 

on the south west to quartz monzonite on the 

northeast. More detailed studies of mineralogical 

and chemical variations in the intrusive rocks 

along the Portland Canal and in the Hyder area 

are underway. 

Detailed geochemical sampling was concentrated in the Bradfield Canal A- 1 quadrangle 

around altered margins of roof pendants of 

Hazelton volcanics and in the sheared granodiorite of Texas Creek where these are intruded 

by rocks of the Coast Range batholith. Reconnaissance geochemical sampling and mapping 

was done in the Bradfield Canal A- 2 quadrangle 

along the eastern margin of the Coast Range 

batholith in the headwaters of the Leduc and 

Chickamin Rivers to search for anomalies similar 

to those associated with the nearby Granduc 

Mine in British Columbia, Canada. Reconnaissance stream sediment sampling in the Ketchikan 

D- 1 quadrangle was also carried out in conjunction with geologic mapping. Several small 

local anomalies of gold, silver, and molybdenum 

were delineated. A geochemical map on the 

results of the geochemical work is in preparation. 

(J. G. Smith, Menlo Park, Calif.) 

Livengood District 

A geochemical anomaly near Ruth Creek in 

the Livengood gold district, about 60 miles northwest of Fairbanks, was reported in U.S. Geological 
Survey Circular 590. The anomaly is defined by -

abnormally high concentrations of several elements (gold, arsenic, mercury, tin, molybdenum, 

and silver) in stream sediments, by highly acid 

stream water, and by gold deposits in bedrock. 

The lode deposits, although small, may be indicative of larger deposits at depth in or below 

major fault zones. (R. L. Foster, Menlo Park, 

Calif.) 

t. Lawrence Island 

The geology of St. Lawrence Island, in the 

Bering Sea about 150 miles southwest of Seward 

Peninsula, is being studied to aid in interpreting 

geologic structures in the Bering Sea and in 

understanding possible controls for the accumulation of gold and other heavy minerals in the 

sea. 

Preliminary investigations in the eastern part 

of the island indicate the presence of a heretofore little known Paleozoic and Mesozoic sequence 

possibly as much as 8,500 feet thick. The oldest 

strata are approximately 4,000 feet of dolomite 

and dolomitic limestone, succeeded disconformably 

by 1,000 to 1,500 feet of cherty limestone. These 

carbonate rocks range in age from Devonian to 

Late Mississippian and include a considerable 

thickness of reefy dolomites. If these rocks 

extend northward and southward beneath the 

shallow Tertiary basins that underlie the Bering 

Sea shelf they could offer major petroleum 

possibilities. 

The Paleozoic rocks are overlain disconformably 

by a 400-foot shaly sequence that is probably of 

Early Triassic or Permian age in the lower part 

and is definitely of Late Triassic age in the 

upper part. The youngest sedimentary rocks are 

a thick section of graywacke and mudstone; no 

fossils have yet been found in them but a Jurassic 

or Cretaceous age is strongly suggested by their 

stratigraphic position and by their similarity to 

rocks of the same age in adjoining parts of mainland Alaska. 

Detailed mapping and geochemical sampling 

in the Boxer Bay area at the west end of the 

island have revealed zinc and molybdenum 

anomalies on the upper Boxer River and lead, 

zinc, and silver mineralization in a belt extending 

northeast from Southwest Cape to the Putgut 

Plateau. (W. W. Patton, Jr., and Bela Csejtey, 

Menlo Park, Calif.) 

10 

East ern Seward Peninsula 

A geochemical and geological reconnaissance 

has been made of part of the western Hogatza 

Trend in the Candl quadrangle (published at 

1:250,000) in the eastern Seward Peninsula. In 

addition, a stream sediment sampling program 

was carried out over a 2,000 sq mi area and the 

intrusive rocks were sampled in detail. This 

work resulted in the discovery of two large 

mineralized areas near Granite Mountain. The 

larger of the two is along Quartz Creek west of 

Granite Mountain where numerous occurrences 

of lead-silver-zinc sulfide minerals were found 

over a length of 18 miles. The other mineralized 

area is east of Granite Mountain in the headwater basin of the upper Peace River, where 

molybdenum-silver-bismuth-lead-uranium minerals were found a sociated with an alkaline 

intrusive stock. These results were reported in 

U.S. Geological Survey Circular 614 (published 

in 1969). 

A zoned alkaline intrusive complex was 

ob erved at Granite Mountain. The complex is 

a circular body 30 sq mi in area with a silicaoversaturated and silica-saturated core and an 

alkaline undersaturated rim. 

Regional mapping and geochemical sampling 

were begun in the eastern half of the Bendeleben 

quadrangle (published at 1:250,000), and several 

mall geochemical anomalies were found . 

Several geochemical anomalies of copper, lead, 

zinc, silver, gold, uranium, and thorium were 

found in the central Koyokuk Ri ver region near 

Hughes and Hog Landing. These findings were 

reported in U.S. Geological Survey ircular 570. 

(T. P. Miller, R. L. Elliott, and 0 . J. Ferrians 

Menlo Park, Calif.) 

Western eward Penin ula • 

Recognition of abundant cassiterite in gold 

placer deposits on Humboldt Creek in the 

Serpentine-Kougarok area was reported in U.S. 

Geological Survey Circular 565. A bedrock 

source for the cassiterite has now been discovered. 

Continued mapping of the Seward Peninsula 

at a scale of 1:250,000 has demonstrated that rocks 

of the entire Seward Peninsula are involved in 

thrust sheets of a major thrust belt. A large ~ terrane of blueschist facies rocks of probable Pre 8 cambrian age has been defined. The Paleozoit t 

stratigraphy, from pre-Ordovician through ~ p 

least the Mississippian, reflects shelf-type sedi-
mentation, and is represented almost entirely by 

carbonate rocks. In the western Seward Peninsula, thrust sheets of unmetamorphosed carbonate 

rocks lie above high rank metamorphic rocks; at 

the east end of the peninsula, the Paleozoic 

carbonate rocks are metamorphosed to marble, 

but rest upon metamorphic rocks of much higher 

rank. 

A regional zonation of mineral deposits is 

suggested, from greisen-type tin deposits on the 

western Seward Peninsula to base-metal deposits 

with silver and moderate amounts of tin in the 

central and eastern Seward Peninsula. (C. L. 

Sainsbury, Denver Colo., and Reuben Kachadoorian, Menlo Park, Calif.) 

outheastern Alaska 

The area around the famous Alaska-Juneau 

and Treadwell gold mines is being studied to 

determine the economic potential of this widely 

mineralized part of Alaska. 

The northeasternmost part of the large Tertiary 

granodiorite-adamellite complex that forms the 

core of the Coast Range northeast of Juneau has 

abundant iron-stained zones within it and near 

it. Spectrographic analysis of samples from 

several of these zones shows that most are not 

economically significant, but one such zone, an 

intensely iron-stained aplite body which is a dik -

like extension of the main composite granodiorite 

complex, wa found to contain as much as 1,000 

ppm molybdenum, 9.6 ppm ilver, and 300 ppm 

copper. The occurrence ha not been mapped or 

sampled in detail. Iron-stained zones are less 

abundant in and near the we t-central part of 

the complex. The complete periphery of this 

Tertiary intrusive complex has not yet been 

studied. 

Study of old reports dealing with the northern 

Juneau Gold Belt suggests that there is a consistent spatial relation between the larger deposits and the contact between a persistent 

metavolcanic unit and a black slate unit. This 

contact is poorly exposed and may warrant 

closer attention than it has received. 

~ S~ream ediment samples from drainages 

1 cuttl~g the host rock unit of the Alaska-Juneau 

, depos1t as much a 15 miles to the northwest and 

'

1 southeast of that deposit give little indication 

;

1 that any similar but undiscovered deposit may be 

i· present. However, some resampling is needed 

11 

in two drainages southeast of the Alaska-Juneau 

mine. 

Large volumes of altered greenschist and 

phyllite containing disseminated sulfides and 

small veins occur on southeastern Douglas Island, 

to the southeast of the Treadwell group of mine . 

The metal content is great enough to cau e 

significant anomalies in stream sediments, but 

analyses of the schists show that the metal content is generally too low to be economically 

significant. However, spectrographic analyses 

of single and composite samples show as much 

as 17 ppm gold, 0.5 ppm silver, 1,000 ppm copper, 

20 ppm molybdenum, 5,000 ppm lead, and 700 

ppm zinc. Stream courses and old mine workings provide the only exposures of the altered 

rocks. (D. A. Brew, A. L. Ford, and A. L. Clark, 

Menlo Park, Calif.) 

Mineral deposits of the belt are characterized 

primarily by arsenic and gold and subordinately 

by silver, lead, zinc, antimony, bismuth, and tin. 

The main deposit ·of the northern part of the belt 

is the Golden Zone, which was discussed in U.S. 

Geological Survey Circular 564. Other principal 

deposits are new identified occurrence at Costello 

Creek and Lookout Mountain and vein and 

associated dis eminated deposits in basalt and 

limestone host rocks at Partin and Canyon Creeks. 

The main deposits of the southern part are placer 

gold depo its of the Cache Creek-Peter reek 

basin in the Yentna district. These placers were 

derived from the erosion of small but rich lode 

depo its uch as those at Bird Creek and probably from erosion of lower grade deposits in 

major shear zones. Arsenic and gold are 

ubiquitou elements of the belt; they characterize 

both lode and placer deposits and have a regionally high abundance in stream sediments. Less 

abundant but diagnostic elements include 

copper, antimony, tin, and bismuth. (C. C. 

Hawley and A. L. Clark, Menlo Park, Calif.) 

Talkeetna Mountains and Centra l Alaska Range 

A mineralized belt called the Chulitna-Yentna 

belt is defined by lode occurrences, geochemical 

anomalies, and placer deposits derived from lodes 

within the belt and extends for more than 100 

miles along the southern flank of the central 

Alaska Range. The belt extends at least from 

Collinsville on the south to Bull River in the 

north and goes through the Yentna, Curry, and 
upper Chulitna districts. It is subparallel to the 

regional strike of rock units and faults and in its 

northern part to elongate serpentinite masses 

which locally contain chromite. 

The Yentna-Chulitna belt is underlain by rocks 

of pre-Permian to Cretaceous age which are cut 

by small igneous bodies of ultramafic to granite 

composition and a major batholith in the Curry 

district. The oldest rocks are in a fault block in 

the valley of the Chulitna River; they are overlain unconformably by red beds, basalt, and 

limestone of Permian and Triassic age which in 

turn are overlain by dark detrital rocks of 

Jurassic(?) and Cretaceous age. The Permian 

and younger rocks were strongly folded and 

faulted in post-Early Cretaceous, pre-Oligocene 

time. 

Wrangell Mountains 

Results of geologic mapping and geochemical 

investigations in the McCarthy B- 4 and B-5 

quadrangles in the southern Wrangell Mountains 

and Chitina Valley were reported in U.S. Geological Survey Circular 604. Anomalous concentrations of copper, silver, antimony, molybdenum, gold, and arsenic and local occurrences 

of tungsten, lead, and zinc were found. (E. M. 

MacKevett, Jr., and J. G. Smith, Menlo Park, 

Calif.) 

Yakutat Region 

Geologic mapping at a scale of 1:250,000 has 

been completed in the Yakutat quadrangle and 

small areas of the adjacent Mount St. Elias 

quadrangle of southern Alaska, and mapping at 

a scale of 1:63,360 is nearly completed in the 

Yakutat D-3 and D-4 quadrangles. All major 

lithologic units and altered zones in the Yakutat 

quadrangle were delineated and sampled, and 

140 stream sediment samples were collected. No 

potentially economic mineral deposits were 

found, although spectrographic analyses indicate 

anomalous concentrations of copper, zinc, vanadium, titanium, manganese, chromium, nickel, 

cobalt, and molybdenum in several altered zones, 

stream sediment samples, and rock specimens. 

In the course of geochemical sampling in the 

Yakutat quadrangle and adjacent areas, float of 

mafic and ultramafic rocks in glacial moraines 

was traced to a pluton on the southwest flank 

of Mount Fairweather. Aerial observation indicated that the float was derived from a stratiform pluton exposed above an altitude of about 

8,000 feet over an area of several square miles. 

The discovery i noteworthy because it extends 

the known occurrence of mafic and ultramafic 

rocks in the Fairweather Range 20 miles farther 

northwest and because nickel-copper deposits are 

known to be associated with bodies of ultramafic 

rock elsewhere in the Range. (George Plafker 

and E. M. MacKevett, Jr., Menlo Park, Calif.) 

AfUZO A 

Lode and Placer Gold Deposits, Mohave County 

Gold deposits in Precambrian rocks of the Gold 

Basin-Lost Basin district in Mohave County are 

closely associated with small masses of quartz 

leucosyenite and aplite that intrude porphyritic 

biotite granite. Fluorite, pyrite, calcite, and gold 

are disseminated in two bodies of leucosyenite. 

Reconnaissance sampling of Quaternal')' 

gravels, colluvium, and prospect dumps. has 

greatly expanded the area of known gold-bearing 

gravels and has revealed appreciable concentra· 

tions of scheelite in some pediment gravels; thE 

source of the scheelite is not yet known. (P. M 

Blacet, Menlo Park, alif.) 

12 

ALIFOR lA 

Geochemical tudie at Bodie 

The Bodie district in Mono County appears tr 

be in the resurgent center of a large volcani 

collapse feature. Th south rim of the featun 

is intruded by one or more rhyodacite plugs an 

is overlain by rhyodacite tuff breccia. In th 

resurgent core, andesite tuff breccia is intrude 

by a north-trending faulted body of porphyri · 

andesite. Although the andesite is not extet 

sively exposed, its occurrence on mine dump 

indicates that it underlies most of the district! 

less than a thousand feet. Quartz veins cut tb 

intrusive andesite and the overlying lavas a 

tuffs. 

At Bodie approximately 400 samples, most 

surface, were collected, including about 100 th! 

were taken in a detailed traverse of the Bod 

Tunnel, which provides a good profile across t1 

major structural trends.. of the district. Mostf 

these samples have now been analyzed. In adG 

tion, 60 orientation samples collected earlier hal 

also been analyzed. The analytical results aJ 

being studied statistically and are summariZi 

as follows: 

1. The average content of gold and silver foUl 

in 29 specimens of vein quartz and ore 
lected on dumps was 19 ppm gold and 216 

ppm silver. In samples of wallrock these 

values drop off sharply, especially those for 

gold. 

2. A correlation analysis on the total set of 

samples shows that the following elements 

have significant positive correlation with 

gold: Bismuth, tin, silver, arsenic, antimony, 

and zinc. The following elements are 

positively correlated with silver: Molybdenum, zinc, gold, lead, antimony, and 

copper. In addition, measurable quantities 

of tungsten and beryllium occur in samples 

that have higher than average contents of 

gold and silver. 

3. Correlation analyses on the 29 samples of vein 

quartz show the same element correlations, 

although the numerical values of the correlation coefficients are higher. 

Potassium-argon ages on adularia-quartz veins 

from different parts of the district indicate that 

mineralization occurred approximately 8 million 

years ago. Three potassium-argon age determinations of plagioclase separated from two 

different samples of the intrusive andesite yield 

an average age of 8.8 m.y. (million years). A 

rhyodacite body intruded along the probable extension of a fault that may limit the collapsed 

part of the district on the south west yielded a 

potassium-argon age of 8.9 m.y. on biotite and 

9.0 m.y. on hornblende. This body may be the 

arne age as, or slightly younger than, the 

postulated collapse. Results so far appear to indicate near contemporaneity of collapse and 

intrusion of the andesite, with mineralization 

following shortly thereafter. 

Fluid-inclusion studies on the adularia used for 

dating the mineralization indicate a temperature 

of homogenization of 245 -+- 5o C. Oxygen-isotope 

studies by J. R. O'Neil on quartz-adularia mineral 

pairs yielded similar results. (F. J. Kleinhampl 

and M. L. Silberman, Menlo Park, Calif.) 

.Mother Lode, Amador ounty 

Detailed mapping of part of the Mother Lode 

in western Amador County has defined the 

probable sequence of geologic events as follows: 

1. Sedimentation, with possible unconformities. 

2. Regional tilting and folding, with development of foliation; possible metamorphism? 

3. Intrusion of basic and ultrabasic rocks at 

depth generally below present exposures. 

13 

4. Faulting in polygonal sets, with probable 

north-south extension and east-west 

shortening. 

5. Intrusion of hypabyssal rocks. 

6. Metamorphism to greenschist facies. 

7. Intrusion of granitic rocks. 

8. Local penetrative deformation forming 

mylonite; second folding? 

9. Faulting to bring about present gross distributional pattern of Paleozoic metamorphic 

rocks and Mesozoic rocks; probable vertical 

extension and east-west shortening. 

10. Fracturing with deposition of quartz veins, 

locally associated with sulfides and gold. 

11. Erosion. 

The structure and, possibly, the stratigraphy 

of the area are extremely complex. The Foothills fault zone of Clark now appears to be a belt 

of complex steeply-dipping polygonal fractures 

in Paleozoic and Mesozoic metasediments and 

metavolcanics, complicated further by igneous 

intrusion. Minor folds can be seen at some outcrops, but the distribution of lithologic units and 

determinations of tops of beds preclude the possibility of large-scale folding in this particular 

region. 

A preliminary aeromagnetic map shows two 

conspicuous north-northwest-trending belts of 

magnetic highs. The western highs correspond 

to a belt of erpentinit xpo ures at the western 

edge of the Foothills fault zone. The eastern 

highs are centered over belts of green phyllite 

and schist, and in part coincide with the Mother 

Lode belt of gold-bearing quartz veins; however, 

this high correlates more closely with the Melones 

fault of Clark. 

The quartz veins of the Mother Lode system 

are poorly exposed in western Amador County, 

and the mine workings are now inaccessible. 

Nevertheless, several samples of altered rock 

adjacent to quartz veins have been collected and 

analyzed for gold and certain other metals. In 

most samples, the gold content is less than 0.02 

ppm, and in nearly all the other samples the gold 

content is less than 0.20 ppm. (W. A. Duffield 

and R. V. Sharp, Menlo Park, Calif.) 

Tertiary Gravels, evada City Area, Sierra Nevada 

Preliminary results of a study of gold-bearing 

Tertiary gravels in the .Sierra Nevada near 

Nevada City were reported in U.S. Geological 

Survey Circular 566. 
Detailed seismic and gravity surveys were 

made on San Juan Ridge to refine earlier interpretations of the position of the buried bedrock 

depression. Rotary drilling of four holes proved 

the existence of expected sands, clays, and 

gravels beneath the volcanic breccia on San 

Juan Ridge but failed to prove the existence of 

a defined channel in the bedrock as indicated by 

the seismic work. A cursory examination of the 

panned concentrates of the cuttings from the 

buried gravels revealed very little gold. 

Three churn-drill holes penetrated 325-465 feet 

of gold-bearing gravel near the center uf the 

wide channel at North Columbia. These holes 

were drilled to check drilling done in 1939 and 

the seismic and resistivity surveys done in 1967. 

Panned concentrates from these three holes are 

being analyzed for gold. Abundant secondary 

sulfides were found in all holes. The depths to 

bedrock in all three holes were very close to those 

predicted from the seismic surveys. 

Two additional shallow holes were drilled near 

the margins of t he hydrauli c pit at North 

Columbia. One drilled near a high gravity 

anomaly entered bedrock at 27 feet, and it is 

reasonable to think that the near-surface occurrence of bedrock at this locality is responsible for 

the gravity anomaly. Another hole drilled at the 

position of an electromagnetic anomaly cut 

several tens of feet of bentonite before hitting 

bedrock at 77 feet. It seems clear that the relatively thick section of clay is responsible for the 

electromagnetic anomaly. 

Density, seismic, electrical, gamma-ray, and 

susceptibility logs are being obtained in the open 

holes on San Juan Ridge, and seismic and gammaray logs, in the cased hol es at North Columbia. 

The susceptibility log is most useful for differentiating between the Tertiary gravels and the 

volcanic breccia; self-potential logs define most 

of the clay-rich zones within the gravel section; 

density and velocity logs show marked contrasts 

at the gravel-basement contact. The contacts 

between the volcanics, gravel, and Calaveras 

basement are difficult to identify on resistivity 

logs. 

Mapping of the ancestral Yuba River drainage 

continued to the south on Washington Ridge. 

The area being mapped includes such notable 

gold mining areas as Sailor Flat, Blue Flat, and 

Scotts Flat. 

14 

On the basis of work of the U.S. Geological 

Survey on the Tertiary gravels, the U.S. Bureau 

of Mines is carrying out detailed geophysical 

exploration, mapping, and sampling within the 

Badger Hill hydraulic pit. This area is on the 

divide between the Middle and South Forks of 

the Yuba River in Nevada County. (W. E. Yeend, 

Menlo Park, Calif.) 

COLORADO 

Gold in astle Rock onglomerate 

In the Ca tle Rock area of Douglas County, 

gold in modern tream alluvium is derived from 

reworking of fossil placers in the Castle Rock 

Conglomerate, of early Oligocene age. Electron 

microprobe studies indicate that individual gold 

grains originating from the Castle Rock Con· 

glomerate average more than 99 percent gold; 

the remainder i chiefly silver. Most of the gold 

grain are less than 1 mm aero s and some are 

as mall as 0.10 mm. Paleocurrent studies indicate that the primary source of the gold apparently is not the Georgetown-Central City 

area to the northwest a previously thought, but 

rather is an area to the west or outhwest of the 

town of Castle Rock, either in th Front Range 

or possibly a far west a th headwaters of the 

Platte River. At present it is not known whether 

the primary source of the gold has been completely removed by erosion or is concealed by 

sediments or faulting of post-early Oligocen age. 

(G. A. Desborough, W. H. Raymond, and . E. 

Soule, Denver, Colo.) 

Ore Deposits of Chicago Basin 

In the Chicago Basin district of th Needle 

Mountains in southwestern Colorado, two hypa· 

byssal porphyries of possible Tertiary age intrude 

Precambrian granite. The older hyperalkalic 

quartz porphyry is pervasively altered and locally 

mineralized, whereas the younger rhyolite por· 

phyry is less altered and appears to be barren. 

Intensely sericitized and silicified porphyry con· 

tains anomalous amounts of arsenic, gold , copper. 

molybdenum, antimony, and tin, particularly on 

the west side of the older porphyry. Anomalom 

amounts of silver, lead, and zinc are more wide])' 

distributed but are also somewhat concentrated 

on the western side. 

The granite enclosing the porphyry complex ~ 

cut by numerous fractures and quartz vein 

Most pyritic quartz veins containing shoots of 
base and precious metal ores are along a belt 

more than 4 miles long and about 2 miles wide 

that trends north-north west. Veins are along 

regional sets of joints, along fractures radiating 

from intrusive centers, and along fractures that 

follow no regional trend. Geochemical anomalies 

of lead and zinc show a zonal distribution around 

the intrusive center, whereas molybdenum is 

distributed along the entire north-north westtrending belt. 

Much of Chicago Basin and Vallecito Basin to 

the southeast lie within an area of intersecting 

east-trending fractures or faults and northtrending joints. This area of structural weakness 

includes the mineralized intrusive center of 

Chicago Basin, vein-associated fluorite mineralization, and the strongest vein-associated silver, 

bismuth, copper, antimony, and tin anomalies in 

the district. Vein-filled joints appear to be concentrated in Vallecito Basin, and most veinassociated metal anomalies are centered in that 

basin rather than in Chicago Basin. An intrusive 

body related to the Chicago Basin center may 

underlie the metal anomalies in Vallecito Basin. 

(L. J. Schmitt, Denver, Colo.) 

Geophysical tudies at Cripple Creek 

Model studies of gravity data along a structure section across t he Cripple Creek volcanic 

basi n, Tell er County, support the concept of a 

ub idence basin whose ba e con ists of a eries 

of granite ridge . These ridges are defined by 

a system of northwest-trending fracture which 

al o were the loci for ore-bearin olution . A 

reasonable fit to observed g ravity is obtained 

using a density contrast of 0.25 g/cm3 between 

volcanic and granitic rock. 

The low-level aeromagnetic map of the Cripple 

Creek caldera is based on 22 lines about 5 miles 

long spaced a quarter of a mile apart and flown 

at 10,700 feet altitude and shows the caldera to 

b marked by a well-defined magnetic low. The 

axis of the principal low correlates with an area 

of minimum gravity and the geochemical anomaly over the Cresson-Mollie Kathleen mineralized 

zone. An east-trending magnetic low is over the 

south part of the district, in which most of the 

gold was produced. Gold content was still high 

at the time mining ceased. Magnetic lows are 

believed to correlate with areas of greatest 

pyritization or maximum alteration of magnetite. 

Strong potassium anomalies recorded during 

15 

ground gamma-ray spectrometry surveys correlated with areas of hyd rothermal alteration 

previously identified by geochemical studies. An 

airborne survey of the area is planned next year. 

(M. D. Kleinkopf and J. A. Pitkin, Denver, Colo.) 

Niobium a11 d Other Elements, Gem Park Complex 

Work in the laboratory and field on the Gem 

Park Complex of mafic-ultramafic igneou rocks 

and associated carbonatites in Custer and Fremont Counties 11 miles northwest of Westcliffe 

has shown that some carbonatite dikes and fenite 

contain concentrations of niobium, rare-earth 

elements, thorium, phosphorus, some other elements, and vermiculite. 

The Gem Park Complex is a small funnelshaped composite body related to the McClure 

Mountain alkalic complex a few mil es to the 

northeast. The Gem Park Complex consists 

mostly of pyroxenite and gabbro with minor 

dikes and bodies of lamprophyre, syenite porphyry, and nepheline yenite pe.gmatite, and 

abundant dikes and irregular bodies of carbonatite, all of Cambrian age. A mass of fenite lie 

near the center of the complex. The whole complex lies discordantly in Precambrian gneis ic 

terrane and is overlain by Tertiary volcanic rocks. 

Large areas in the complex are covered by Quaternary alluvium and colluvium. The arrangement of carbonatite dikes, t he position of t he 

f nite, and other f ature ugg t that a large 

carbonatite body lies beneath the surface near 

the center of the complex. 

The hydrou nickel arsenate annabergite has 

been identified in one of the carbonatite dikes. 

This finding indicates the presence of a primary 

nickel mineral, probably niccolite. The mine reported long ago by Cros and Genth to have 

produced niccolite ore may have been here. 

U.S. Geological Survey Prof. Paper 612, Geochemistry of niobium and tantalum, by R. L. 

Parker and Michael Fleischer, wa published in 

1968. (R. L. Parker, Denver, Colo.) 

Silver and Copper in McElmo Canyon 

The Bluff Sandstone (Upper Jurassic) in a 

west-northwest-striking shear zone which passes 

through Battle Rock in McElmo Canyon, ~ontezuma County, contain anomalously high amounts of silver (4 to 50 ppm) and copper (270 

to 14,000 ppm) for at least a mile west-northwest of the Battle Rock prospect. The prospect 

and the Karla Kay uranium mine, 2 miles west-
northwest, appear to lie on the same shear zone. 

A wide fault zone that strikes northeast intersects the Battle Rock shear zone about 1 mile 

west-northwest of Battle Rock. Anomalous 

copper and detectable gold were found in one 

locality in the Entrada Sandstone (Upper Jurassic) in the fault zone 3 miles northeast of Battle 

Rock, and samples of mud from a carbon dioxide 

well 0.3 mile north of this locality showed high 

copper (70 ppm) and silver (1.6 ppm) and detectable gold (0.02 ppm). Bluff Sandstone in the 

fault zone at its intersection with the McElmo 

Canyon road contains high silver (2 ppm). Results of the geochemical study to date suggest 

that the fault and shear zones contain the highest metal anomalies and probably contain or lie 

adjacent to any economically important metal 

deposits which may be present in the area. (R. 

A. Cadigan, Denver, Colo.) 

Copper and Silver in Precambrian Rocks Near Gunnison 

Anomalous amounts of copper have been found 

in Precambrian metamorphic rocks exposed in a 

roadcut along U.S. Highway 50 in sec. 30, T. 49 N., 

R. 2 W., about 11 miles west of Gunnison in Gunnison County. Analyses of samples from 14 50-

foot intervals along the roadcut show that samples in five of these intervals have median 

contents of copper ranging from 20 to 230 ppm; 

from five to 11 samples in each interval were 

analyzed. The richest sample contained 26 percent copper. Median silver content ranged from 

0.4 to 1.0 ppm. (R. A. Cadigan, Denver, Colo.) 

Geology of Hahns Peak and Vicinity 

The study of the general geology and mineral 

deposits in the Hahns Peak and Farwell Mountain quadrangles, Routt County, has been completed. Reports in preparation will include 

geologic maps and sections of the two 71

h-minute 

quadrangles; descriptions of the stratigraphy; 

igneous and metamorphic geology; structure of 

the area; chemical, mineralogical, and petrographic data; and the results of radiometric age 

determinations. 

A detailed geologic map of Hahns Peak and 

vicinity will depict the geology of a mineralized 

area of approximately 2.5 sq mi at a scale of 1 

inch equals 400 feet. The map will also show 

silver, lead, and zinc geochemical anomalies, and 

induced polarization and electrical resistivity 

anomalies. (Kemieth Segerstrom, Denver, Colo.) 

Lookout Mountsin Area, Eastern an Juan Mouutains 

A base-metal geochemical anomaly in the Lookout Mountain area on upper Alamosa Creek south . 

of Summitville was reported in U . . Geological 

Survey Circular 557. A lead anomaly more than 

1.5 sq mi in extent and lesser anomalies of copper, 

molybdenum, and zinc occur in altered silicic volcanic rocks, quartz monzonite, and quartz latite 

porphyry. The area is geologically similar to the 

productive Summitville district and is an attractive exploration target. (W. N. Sharp and J. L. 

Gualtieri, Denver, Colo.) 

16 

orthwestern San Juan Mountains 

A detailed geologic and geochemical study of 

the strongly mineralized area around Ouray in 

the northwestern San Juan Mountains was begun 

in 196 . 

Fieldwork to date has included detailed mapping of the Red Mountains area and pilot sampling 

studies for geochemical control. Reconnaissance 

examination of the extensive vein ystems in the 

area suggests that studies of trace-element content of selected ore and gangue minerals will 

perhaps be the most fruitful method of examining 

possible zonation and paragenetic relationships 

of the vein sy tern, and some initial sampling of 

vein material was done. tudies are also being 

made on experimental design and development 

of the computer programs necessary to handle 

the statistical and geochemical data. (F. . Fisher, 

Denver, Colo.) 

ilver Iiff-Rosits District 

Restudy of the Silver Cliff volcanic center in 

the Silver Cliff-Rosita district, which in the past 

was prospected extensively and mined for silver 

and some base metals, has defined two early volcanic throats and a foundered block of layered 

volcanic rocks centered between the two volcanoes. 

The rather small area of volcanic rocks (6-7 sq 

mi) remaining at Silver Cliff represents only the 

remnant of a much greater volcanic inundation. 

The two volcanoes, which appear to have been 

predominantly latitic in character at the outset, 

apparently broke through onto a Precambrian 

terrane in late Oligocene time and must have 

poured out several cubic miles of ash and breccia, 

very little of which is presently exposed A block 

several square miles in area, including a thick sec· 

tion of these early ejecta, dropped gradually into 

the underlying magma chamber. Rhyolitic flows 

and ash vented along the faults bounding thi 
downdropped block and continued to ov~rflow 

the area and fill in the subsiding block. Cores 

from a series of exploratory drill holes put down 

by Congdon and Carey Mining Co. in 1966-67 disclose that the lower parts of some of the holes 

cut thinly layered "lake beds" of volcanic ash 

and pellet conglomerate. The deepest holes, 700 

to 800 feet long, bottom in "lake beds"; therefore, 

the foundered volcanics are dropped at least that 

amount relative to exposed peripheral Precambrian rocks. 

Gravity surveys suggest that volcanic centers 

may be outlined by this method. Measurements 

have been made at more than 200 tations. A 

gravity minimum of 5 milligals or more corresponds with a subsidence area underlain by rhyolite, and local lows near Round Mountain and 

Ben West Hill may outline volcanic centers. 

A seismic refraction profile 3 miles long south 

of Westcliffe crossed a suspected fault bounding 

the northea t side of Wet Mountain Valley. 

Minor faults may have been recognized near the 

south end of the profile. Three other lines across 

a volcanic ubsidence area for 4 miles north from 

Westcliffe revealed a strong velocity contrast between Precambrian ba ement (about 23,000 f t 

per econd) and overlying olcanic breccia (about 

12,000 fp ). Thick volcanic breccia was indicated 

ju t north of Ben We t Hill and about threequarters of a mile north of We tcliffe, an area indicated by geological and gravity data to be the 

d epest part of the volcanic basin. 

Faults radial and peripheral to the volcanic 

throats are mineralized almo t exclu ively with 

ulfides of iron zinc, lead, and copper with minor 

ilver and gold. The foundered block itself is unevenly broken and fractures are filled . ' w1lh veinlet of predominantly iron, manganese, 

a~d calcium carbonates carrying unevenly distributed sulfide of iron, lead, zinc, and silver. 

In the near surfac part of thi block (down to 

100- 200 feet) the e carbonate veinlets are weath1 ered and oxidized so that t he rocks are stained 

with iron and manganese. Veinlets of black 

1 o~id~s of iron and manganese contain unevenly 

d1stnbuted silver and are locally enriched in silver halides. 

K Preliminary analyses indicate that all the rocks 

of the foundered block are enriched in chlorine 

o bromine, and iodine. The distribution of halide~ ?ver ~h~ Silver Cliff volcanic rocks may aid in 

1dentlfymg exploration targets. (W. N. Sharp 

and M. D. Kleinkopf, Denver, Colo.) 

17 

GEORGlA 

Dahlonega Gold Belt 

A geochemical reconnaissance of the Dahlonega 

gold belt has been completed. Rocks of the belt 

consist of interlayered mica, graphitic and garnet-rich schist, quartzite, and amphibolite that 

generally trend northeastward. Near Dahlonega . 

and in parts of Cherokee, Paulding, and Carroll 

Counties the schists are intruded by dike and 

small plutons of granite. From central Cherokee 

County northeast to Rabun County, a fault or 

shear zone probably separates the Dahlonega belt 

on the northwest from an extensive area of migmatite and granite on the southeast. In this part 

of the belt the mica schists seem to grade westward into mica gneiss typical of the Blue Ridge. 

In the southwestern part of the belt the eastern 

boundary may be the Brevard fault zone, and the 

western boundary the Cartersville or po sibly the 

Whitestone fault. Locally the mica schist seems 

to grade we tward into less metamorphosed phyllites and graywackes of the Ocoee Series. 

Reconnaissance sampling in the Dahlonega belt 

indicates that small amounts of gold can be obtained from mo t of th old min s, and trace 

amounts, generally less than 0.2 ppm, are widespread in the country rock throughout the area. 

Over 1,6 0 ample of various rock types, minerals, and soil were collected in 40 old mines and 

along roadcuts across the trend of the gold belt 

in an area 145 miles long and 2 to 25 miles wide. 

Three hundred and six or 69 percent of the 558 

mine amples and 236 or 21 percent of the 1,106 

roadcut samples contained 0.02 ppm or more gold. 

About 90 percent of the samples are saprolite 

or weathered rock. A comparison of sample data 

for fresh and weathered samples suggests some 

residual enrichment of gold in weathered rocks of 

the mine areas. Such enrichment is indicated at 

the Calhoun mine in Lumpkin County, where samples of mica schist saprolite from the opencut contained 0.02-0.1 ppm gold, whereas 17 samples of 

fresh mica schist from underground workings 

below the opencut contained no detectable gold. 

Although gold is distributed widely throughout 

the district, the gold content of the average goldbearing sample is small. Half of the mine samples 

and three-quarters of the roadcut samples that 

are gold-bearing contain less than 0.2 ppm gold, 

and only 20 mine samples contain 5 ppm gold or 

more. (F. G. Lesure, Washington, D. C.) 
MAINE 

Mineral Deposits ear West Pembroke 

Detailed mapping in the area of the Barrett and 

Big Hill prospects near West Pembroke in Washington County, and study of approximately 0,000 

feet of drill core that were made available by 

Consolidated Dolsan Mines, Ltd., have disclosed a 

well-defined pattern of mineral zoning. The sulfide deposits are along irregular fractures and 

small faults in weakly metamorphosed felsic and 

spilitic flows, tuffs, and shallow marine shales of 

Silurian age. The central part of the zoned area 

is about 1,000 by 500 feet in extent at the surface, 

but broadens in depth. It i characterized by intensely altered rock, some copper, and sporadic 

gold. It is succeeded upward and outward by a 

zone rich in zinc and then by a peripheral zone of 

lead, zinc, and silver. Ore mineral are chalcopyrite, sphalerite, galena, tetrahedrite, arsenopyrite, 

pyrite, possible silver sulfarsenides, native gold, 

and pos ible gold telluride minerals. Gangue 

minerals are carbonates, quartz, and barite. 

The regional geochemical work generally confirmed the work of Post and others (1967). However, inasmuch as the gold contents of panned 

concentrates of stream and beach ediments that 

were sampled in 1967 correlated approximately 

with the distribution of sandstone of the Perry 

Formation, a largely fluvial deposit of Late Devonian age, the sandstone itself was sampled for 

its gold content in 1968 but samples gave entirely 

negative results. Panned concentrates of beach 

sediments adjacent to the Perry Formation were 

obtained at the same time. Of 97 concentrates, 

25 showed detectable amounts of gold, ranging 

from 0.02 to 2.2 ppm. Concentration factors in 

samples with detectable gold range from 3,000 to 

one to 400 to one. Using approximate concentration factors, the maximum gold content of 

beach sediments obtained during 1967 and 1968 

sampling is about 0.04 ppm. (R. H. Moench, 

Denver, Colo.) 

Interpretation of Geophysical Logs, Burnt ubble Area 

Preliminary interpretation of geophysical logs 

of drill holes at the Burnt ubble prospect northeast of The Forks indicates the following: 

1. Unmineralized gabbro and norite h.ave 

moderate to high resistivity (10 3- 10 4 ohm-meters), 

relatively low gamma-ray intensity, and low magnetic susceptibility. · 

2. Hornfels has very high resistivity (> 105 

ohm-m), relatively high gamma-ray intensity, and 

18 

low magnetic susceptibility. 

3. More than 15 percent of pyrrhotite by volume 

apparently is n ces ary to make these rocks electrically conductive. 

4. The pyrrhotite in rocks of thi area appears 

not to be ferromagnetic, as measured susceptibility is less than 10 - 3 cgs units. 

Airborne electromagnetic urveys of a small area 

near the Burnt Nubble prospect revealed good 

anomalies probably cau ed by pyrrhotitic slate 

and the pyrrhotite body that was drilled in 1967. 

Chemical analyses of drill cores for copper, 

cobalt, and nickel have been completed; in general, 

the combined content of thes metals is 0.1 to 0.3 

percent, but a few analyses give somewhat higher 

re ults. (F. C. Canney, Denv r, Colo.) 

MA ACH U EITS 

Gold in Ores From ewbu ryport District 

Closely paced sampling in the Newburyport 

silver-lead district in northeasternmost Massa· 

chu etts has revealed two distinct northeast· 

trending gold anomalies, possibly along the 

Newburyport fault ystem. Samples of gangue 

minerals from the dumps of the Chipman mine 

as ayed about 2 to ppm gold, those from the 

ewhall Farm prospect 0.2 to 2 ppm, and those 

from the Dodge prospect 0.1 to 0.2 ppm. Gangu 

material from copper prospects, as well a samplel 

of barren rock and alluvial soils, contained 0.04 to 

0.1 ppm gold. (J.P. D'Agostino, Beltsville, ~d. 

MO TANA 

Gravity urvey at Neihart 

A gravity survey has been made in th Little 

Belt Mountains at Neihart, Cascade County, in an 

effort to delineate the subsurface extent of the 

Snow Creek Porphyry (post-Cretaceous(?)), which 

is associated with deposits of silver, gold, and bast 

metals in the Neihart district. Gravity observa· 

tions were made at 342 sites across exposed ana 

postulated buried parts-of the porphyry and al 

around the periphery of the porphyry body. ( I 

D. Kleinkopf, Denver, Colo.) 

Virginia City Di trict 

Geologic mapping in the Virginia City district 

Madison County, indicates that the gold-silver· 

quartz veins are discontinuous and of restrict€( 

extent. Beds of dolomite, 5-50 feet thick, local!. 

define structure and limit the postulation of faulb 

in the Precambrian gneissic rocks. 
Analyses of the gold content of soils indicate 

that soil sampling may aid in detecting and tracing gold veins in the district; most high gold 

analyses could be correlated with known ore deposits. Of 911 samples, 38 had 0.1 ppm gold or 

more, 45 had 0.04- 0.09 ppm, 58 had 0.02- 0.03 ppm, 

and 770 had < 0.02 ppm. 

Ages of some of the Tertiary volcanic rocks in 

the general area of Virginia City have been measured by the potassium-argon method. Biotite 

from andesite porphyry gave 49.3 m.y., biotite 

from a rhyolite plug gave 44.7 m.y., whole rock 

from two basalt flows gave 32.7 m.y. and 30.3 m. 

y., and whole rock of basalt from Black Butte (a 

probable volcanic neck 20 miles south of Virginia 

City) gave 23.1 m.y. The ages suggest a more 

complex igneous history than is apparent from the 

geologic relationships. (K. L. Wier and R. F. 

Marvin, Denver, Colo.) 

EVADA 

Aurora District 

The ore-bearing rock in the Aurora district, 

Mineral County, is andesite of unknown age, overlapped and intruded by younger andesitic to 

rhyolitic volcanic rocks. Som of the young r 

rocks appear to be postmineralization in age. Approximately 00 ample of altered (argillized, 

propylitized, and ilicified) rock and quartz veins 

were collected in 196 for pectrographic analysis 

and ch mica! analy i for gold, ilver, arsenic, antimony, zinc, tellurium, molybdenum and mercury. 

Approximately 200 samples of altered rocks from 

outside the main Aurora district will be analyzed 

to evaluate the potential for additional ore deposits outside the main district. About one-half 

of the Aurora amples have been analyzed. Prel~minary geochemical anomaly maps for gold, 

sliver, and molybdenum indicate the following: 

1. Silver and gold values are highest in the 

northern part of the district and are concentrated 

around a small rhyodacite intrusive. A secondary 

and areally smaller concentration occurs on Silver 

Hill in the southern part of the district. 

2. No low-grade wallrock mineralization has 

been found in the di trict. Quartz veins yield 

spotty assay results, although gray.:streaked 

t quartz, which is mentioned as a guide to ore in 

numerous old reports, generally contains several 

parts per million gold, and as much as ten times 

greater amounts of silver. 

19 

3. Background values of 0.02 to 0.06 ppm gold 

and 0.5 ppm silver in the propylitized, argillized, 

and silicified rocks of the district are anomalously 

high when compared to the average for the particular rock type in question. The values approach 

the detectability limits for these elements and 

may not be reliable. 

4. Anomalously high values of molybdenum (up 

to 2 percent) have been found in quartz veins and 

limonite-coated fractures in a small area in the 

northern part of the district. Molybdenum apparently is not found elsewhere in the district in 

anomalous amounts, nor in the surrounding 

region. It may be related to a Mesozoic(?) granite 

lying beneath the basal andesite of Aurora, which 

is approximately 1,000 feet thick. 

5. A possible breccia pipe complex crops out on 

the summit and southern flank of "East" Brawley 

Peak, approximately 1 mile south of the main part 

of the district. The outcrops consist for the most 

part of dense, silicified, extremely brecciated rock. 

The rock is commonly bleached white and has 

scattered hematite- and limonite-stained patches 

as well as a few concentrations of sulfides. Chemical analyses of samples are as yet incomplete, 

but amples not parti ularly rich in ulfide how 

a low but anomalous silver content, averaging 0.4 

ppm. The presence of sulfides and the brecciated 

rock, which might produce a good host for ore at 

depth beneath the oxidized zone, make this an 

interesting area for further exploration. 

Several volcanic units of basic to felsic composition intrude and overlap the mineralized andesite 

at Aurora. Potassium-argon analysis by Gilbert 

and others (1968) on an andesite flow overlying 

the mineralized andesite yielded an age of 12.4 

m.y., indicating that mineralization occurred before that date. Potassium-argon ages on biotite 

and hornblende, 2.6 and 2.5 m.y. respectively, were 

obtained on a latite plug that forms a part of the 

eastern margin of the district. These dates 

indicate that volcanism was continuous in the 

Aurora district over a period of at least 10 

million years and that ore mineralization was 

early in the sequence of events. (F. J. Kleinhampl 

and M. L. Silberman, Menlo Park, Calif.) 

Carlin Mine 

Geologic mapping in and around the Carlin gold 

mine in Eureka County shows that the gold mineralization is strongly influenced by structural 

controls. Premineralization faults and shear 
zones, and the intersections of these features, 

provided channels for ore solutions. The amount 

and extent of shattering in the surrounding rock 

controlled the lateral movement of the solutions 

outward from the main structures. 

In addition to gold, numerous other elements 

were introduced into or concentrated within area 

of mineralization. These include arsenic, antimony, barium, boron, cobalt, copper, lanthanum, 

lead, manganese, mercury, molybdenum, nickel, 

niobium, scandium, tungsten, and zinc. The total 

abundance range for any element is much greater in mineralized than in unmineralized rocks. 

Normal fresh Roberts Mountains Formation, the 

host rock for the gold deposit, contains only very 

minor amounts of most elements. 

Three distinct types of carbonaceous material 

are present in the Roberts Mountains Formation. 

These include an activated carbon, mixtures of 

high molecular weight hydrocarbons, and an 

organic acid similar to humic acid. All three are 

important in controlling deposition of gold from 

hydrothermal solutions. Gold complexes in the 

ore solution interacted with these materials and, 

in the case of humic acids, the gold was removed 

from solution and chemically bound to the acid 

molecule. During late oxidation these compounds 

were decomposed and metallic gold was released. 

(A. S. Radtke, Menlo Park, Calif.) 

Copper Canyon 

A detailed study is being made of the Copper 

Canyon copper-gold deposit southwest of Battle 

Mountain in Lander County. The project includes 

a detailed study of stratigraphy and structure 

around the deposit; detailed mineralogy of 

sulfides, oxides, and silicates; wallrock studies to 

determine hydrothermal alteration assemblages; 

and geochemical studies to determine distribution 

and concentration of elements in fresh and altered 

rocks. 

A broad pyritic halo surrounds the Copper 

Canyon deposit, and initial efforts have been directed toward determining the primary rock 

dispersion pattern of gold and other major and 

minor elements around the deposit. Deep core 

drilling by the U.S. Geological Survey at Iron 

Canyon has provided geochemical information on 

the pyritic alteration in the third dimension. The 

fact that a hole 2,672 feet deep and collared within 

the halo penetrated altered rocks only to to a 

depth of about 1,100 feet suggests that the halo 

dips in toward the center of metallization. The 

drill hole was entirely in chert and argillite of the 

Scott Canyon Formation (Lower or Middle Cam. 

brian(?)). In the alter d drill core, copper, barium, 

manganese, zinc, chromium, nickel, and to a lesser 

extent lead and molybdenum, ar several times 

greater than background. Barium and manganese 

are the elements that best reflect the extent of altered rock. (T. G. Theodor , M nlo Park, Calif.) 

ortez-Mill Canyon-Buckhorn Area 

Detailed g ologic studies are being made 

around the Cortez and Mill Canyon districts in 

Lander County and the nearby Buckhorn area it 

Eureka County. Results of geochemical inve tigations at Mill Canyon wer reported in U.S. Geological Survey Circular 606. 

20 

The Cortez di seminated gold deposit is ir 

laminated silty dolomitic, pyritic, carbonaceou: 

limestone in the upper part of the Roberts MoUJr 

tain Formation in a fracture zone near a biotitequartz- anidine porphyry dik of Oligocene age 

The host rock has been hydrothermally altered b: 

oxidation and leaching from a dark-gray rock 

on e grading from light gray to r ed dish gra) 

Mineralization was accompanied by leaching o 

carbonate and carbon and addition of silica. Th 

iron content remained constant. Gold wa at 

companied by trace amounts of m rcury, arsenic 

antimony, tungsten, and copper. 

At Buckhorn Mine, gold and ilver occc 

with pyrite and marcasite along faul associat~ 

with horst and graben structure in Pliocene basa 

tic andesite. Progressive alteration has changf 

the andesite to montmorillonite and then to ka 

linite through a leaching proces . Gold and ilv 

accompanied by trace amounts of ar enic ar 

mercury, are found in the altered material. 

Regional geochemical maps of the ortez-Bu 

horn area show that carbonate rocks in the Jow1 

plate of the Roberts Mountains thru t fault co: 

tain stronger anomalies than cherts of the upp 

plate. Metals that commonly occur in anomaio· 

amounts with gold and silver are mercury, arsell 

antimony, copper, lead, and zinc. Molybdenu 

and tellurium anomalies are also present. 'll 

stronger anomalies in both upper and lower-pia 

rocks are near granitic igneous rock masses a' 

are localized along fracture systems, commonly 

association with altered wallrock. Mineralizaf 

does not appear to be selectively associated wi 

the Roberts Mountains thrust. (J.D. Wellsa 

J. E. Elliott, Denver, Colo.) 
Gold Acres and Tenabo Districts 

The results of a geochemical study along the 

east flank of t.he Shoshone Range in the vicinity 

of Tenabo and Gold Acres, Lander County, were 

presented in B.S. Geological Survey Circular 589. 

Chemical analyses of 1,875 rock samples show 

that the gold-mining centers at Tenabo and Gold 

Acres lie in well-defined northwest-trending belts 

enriched in many elements. 

Part of the mineral belt through Gold Acres 

contains bleached bedrock and has fractures along 

which rocks are greatly enriched in bismuth, 

copper, mercury, zinc, and other metals. The 

Roberts Mountains thrust in this area might reasonably provide an exploration target, because 

the nearby large open-pit mine at Gold Acres 

lies in the breccia zone of the thrust and was one 

of the largest producers of gold in evada in the 

1950's. To determine the depth to the thrust, 

drilling was conducted in the spring and summer 

of 1968 at a site of 0.85 mile northwest ·of the 

open-pit mine. The thrust was cut at a depth of 

1,706 feet, but no appreciable breccia zone was 

found. Rocks above the thrust consi t of chert 

and argillite; those below the t hrust consist of 

lime tone and tactite to the bottom of the hole 

at 1,926 feet. The hole was drilled a few hundred feet north of the enriched area of bleached 

bedrock, mainly to avoid penetrating granitic 

rock before intersecting th thru t, and only trace 

amounts of gold were found, mo tly above 1 200 

feet. 

A cor hoi , completed in th summ r of 196 

at the former site of the town of Gold Acres, wa 

drilled to obtain stratigraphic information in the 

lower plate of the Roberts Mountain thru t. 

The drill penetrated carbon-rich limeston of 

probable Devonian age from the urfac to the 

bottom of the hole at 663 feet. Deeper drilling 

was not attempted becau e of the inten ely fractured condition of the rock. A few samples from 

the core contained gold at the lower limit of detection (0.02 ppm). 

Studie of the open-pit min at Gold Acres 

show that numerous steep and some flat-lying 

faults of probable Tertiary age cut the breccia 

zone of the Roberts Mountains thrust. High 

gold values occur (1) along the fau lts, (2) in tabular and lensoid blocks of sedimentary rocks 

dragged into the breccia zone, and (3) in fractured 

fel ic dikes that cut thrust blocks. Mineralized 

21 

blocks from the lower plate consi t of the Roberts 

Mountains Formation of Silurian age, and block 

from the upper plate belong to the Slaven Chert 

of Devonian age. 

Gold deposits at Tenabo are spatially associated 

with dikes of felsite porphyry and are thought 

to have formed more or le s contemporaneously 

with them. Biotite from a dike near Tenabo 

has been dated at 34.4 =: 1.0 m.y., and anidine 

from the same dike, at 34.7 _ 1.6 m.y. (C. T. 

Wrucke and T. J. Armbrustmacher, Menlo Park, 

Calif.) 

Goldfield District 

Detailed geologic mapping of the western twothirds of the altered area at Goldfield E meralda 

County, has been completed. The area mapped 

to date is approximately 5 miles square, with its 

southwest corner near the town of Goldfield. As 

a result of the mapping, the stratigraphy of mo t 

of the prealteration volcanic unit i being revised. The oldest volcanic unit is a rhyolitic 

welded tuff (formerly called Vindicator Rhyolite). 

It is overlain by a sequence of latitic and quartz 

latitic tuffs and flow latite (all previou ly called 

la tit ), followed by another eq uence of tuff 

and a flow, thi time of rhyoli tic compo ition (all 

previously call ed Sandstorm Rhyolite). Andesite flows blanket these uni ts and spread over 

pr -TertiaiJ rocks to.the southeast and probably 

to the north a well. Dacite domes and flows 

locally intrude and cover the ande ite. The 

largest dacite intru ive-extru ive complex is located on the ea t ide of the area, at Diamond 

Peak; here one or more early dacite domes are 

locally covered by a thick dacitic laharic breccia, 

and both domes and breccia are covered by a 

thick, extensive dacite flow. The dacitic welded 

tuff on the south side of the area (formerly called 

dacite vitrophyre), previously thought to be the 

oldest postalteration unit, i altered itself and 

may also be a product of the Diamond Peak volcanic center. 

The complex fault pattern shown so far by the 

detailed mapping cannot be explained ea ily as 

one et of concentric collapse features, or even 

as an asymmetric collapse followed by partial 

resurgence. Features formed during one or two 

periods of collap e were apparently modified by 

a major east-west fracture zone on the outh ide 

of the area and later by westward tilting and 

north- to northwest-trending basin-range fault-
ing. Although orne collapse may have followed 

both the latitic and rhyolitic eruption cycle , 

most of the collapse features now visible formed 

after eruption of the andesitic and dacitic pyroclastic materials that now occur in the eastern, 

southeastern, and southern parts of t he area. 

Almost all the ore deposits are along fault sy -

terns that probably represent the margins of the 

oldest collapse area. The unique complexity of 

these particular fault systems may be the result 

of repeated movement produced by later structural events. 

Analyses of geochemical sample collected in 

1966 and 1967 have been completed. Background 

values are being determined for the various rock 

units described above and for their altered equivalents. Geochemical data for surface samples 

showed a lead anomaly in the vicinity of Preble 

Mountain, but sub urface samples indicate that 

this anomaly probably does not extend to depths 

greater than a few hundred feet. The origin of 

the anomaly is not yet known. 

Whole-rock X-ray tudy of amples along 10 

profiles across veins in the altered area confirms 

earlier work howing that the assemblage quartzalunite-kaolinite is typical of zone of intense 

ilicification. Other minerals in and near silicified zones include halloysite, nacrite(?), diaspore, 

and beta-cristobalite. At increasing distances 

from silicified zon es, t he assemblages quartzillite-kaolinite (pootassium feldspar of hydrothermal origin occurs in some rocks) and quartzmontmorillonite-illite-relict plagioclase are characteristic. Mineral a semblages resulting from 

hydrothermal alteration are the same over the 

entire district, r egardl ess of proximity to orebearing areas and of the nature of the original 

rock (latite, dacite, or andesite). (R. P. Ashley, 

Menlo Park, Calif.) 

Independence and Adobe Ranges 

Geologic and geochemical studies are being 

made in central Elko County as part of a broad 

study of the mineral potential of north-central 

evada. 

The southern Independence Range, extending 

40 miles northward from Carlin, includes peaks 

at Swales Mountain, Lone Mountain, and Wheeler 

Mountain. The range consists of carbonate rocks 

of Ordovician to Mississippian age in the lower 

plate of a major thrust fault and rocks of Ordovician to Devonian age in the upper plate. The 

22 

fault eparating t he e plates of contrasting rock 

type can be regard d a th Rob rts Mountains 

t hrust fault, although orne vidence indicates 

it is much you nger tructure. Both the upper 

and lower plates and the thrust fau lt have been 

folded into a compl x anticline by forcible intrusion of quartz monzonit . Radiometric dating 

indicate thi ev nt took plac in Oligocene time, 

38 million years ago. Intru ive rocks are exposed 

along th crest of the anticlin at wale Mountain and Lone Mountain, and aeromagnetic data 

indi cate intrusive ro ks lie beneath Wheeler 

Mountain. Intrusive contact zon s have been 

mineralized at Swales Mountain and Lone Mountain, and the thru t zon at Lone Mountain 

wa min ralized in th area of the Rip Van 

Wink! mine. Weak geochemical anomalie at 

Wheeler Mounta in point to po si ble subsurface 

mineral deposits imilar to the xposed deposits 

at wales Mountain and Lone Mountain. Reults of geochemical tudi at wale Mountain 

were reported in U.S. Geolo ical urvey Circular 

5 

The Adob Range, ext nding about 40 mile 

northeastward from arlin, con i t mainl y of 

upp r Paleozoic rocks. At the northern nd of 

the range, iliceous Ordovician and ilurian rock 

overlie Missi ippian hale on a thru t fau lt which 

extends across t he northern half of T. 3 

R. 56 E. Some of the altered br cciated rock 

along t his fault contain anomalously high amounts 

of lead and zinc, but no ample wa found that 

contained more t han 1 percent of ith r m tal, 

and the quantities of gold and sil v r w r negligible. 

On the we t side of Marys Ri ver on the bound· 

ary between T. 3 N., R. 59 E., and T. 39 ., 

R. 59 E., upper plate rocks of the Rob rts Moun· 

tains thrust fault are intruded and altered by a 

large stock of quartz diorite. ndoubtedly thi 

intrusive intersects lower/ plate carbonate rock 

and the thrust fault at depth. Subsurface min· 

era! depo its are possible along the intru ive 

contacts, especially those with lower plate rocks 

and along the thrust zone. 

Siltstone, limestone, and chert beds of Permian 

age in the Adobe Range in T. 34 ., R. 54 E. , and 

T. 38 ., R. 56 E., are significantly phosphatic. 

The phosphate resembles that of the Phosphoria 

Formation, consisting of rounded pellets, irreg· 

ular grains, and fillings and replacements of 

spicules and pelecypods. The average P2 0 s con· 
tent of 75 samples selected at arbitrary intervals 

from 5,000 feet of section is more than 1 percent 

and the maximum is 13 percent. (K. B. Ketner, 

Denver, Colo.) 

Manhattan Mineral Belt 

The Manhattan mineral belt in Nye County is 

a northwesterly-trending zone that includes, 

from northwest to southeast, the Lodi mining 

district in the Broken Hills Range, the Mammoth 

district in the Paradise Range, the Union district 

in the Shoshone Mountains, and the Manhattan 

district in the Toquima Range. Published geologic maps of these districts clearly how that 

northwesterly faults older than Tertiary volcanic 

rocks have localized many of the important mineral deposits. Together the faults form a zone 

alined within the Manhattan mineral belt and 

bordering the northwestward-trending Walker 

Lane of right-lateral strike-slip movement. In 

this zone, much of the country lying between the 

mining districts is covered by Tertiary volcanic 

and sedimentary rocks which undoubtedly conceal other northwesterly faults or extensions of 

those shown on the published maps. The frequency of mineral deposits known in the exposed 

rock of pr volcanic age sugge t that numerou 

undiscover d deposit lie beneath the Tertiary 

rocks along buried trand of th north we terly 

fault zone. (D. R. haw and F. G. Poole, D nver, 

Colo.) 

heep reek Range 

Highly anomalous concentrations of zinc, arsenic, mercury, silver, copper, and lead in siliceou 

rocks in the upper plate of the Roberts Mountains thrust fault along the we t side of the 

Sheep Creek Range north of Battle Mountain in 

Lander County were reported in U.S. Geological 

Survey Circular 595. The pre ent evidence indicates that these anomalies are leakage halos from 

a mineralized source below, possibly along the 

thrust or in the carbonate rock below the thrust. 

(G. B. Gott and C. J. Zablocki, Denver, Colo.) 

Tuscarora Range 

Geologic mapping to date in the Tuscarora 

M?untains, Elko County, shows that these mounta~ns are a relatively simple horst of lower PaleoZOic roc~s of the western assemblage, overlain 

by Tertiary rhyolite tuff and andesite and intruded by a stock of quartz diorite. Downthrown 

blocks on both sides of the horst are mineralized 

but the greatest production has come from th~ 

23 

Tuscarora mines in the block on the east. Gold, 

silver, and mercury have been produced from both 

downthrown blocks, and a crude zonal structure 

can be recognized, with the mercury peripheral 

to the gold and silver deposits. The age of neither 

the volcanic activity nor the mineralization has 

yet been determined. (R. R. Coats, Menlo Park, 

Calif.) 

Virginia City District 

Results of geological, geochemical, and geophysical studies north of the Comstock mining 

district, Virginia City, Storey County, were published in U.S. Geological Survey Circular 596. 

Reconnaisance geochemical sampling of altered 

volcanic rocks revealed anomalous amount of 

mercury in the Cornwall Knob and Washington 

Hill areas, about 5 and 11 miles respectively 

north of Virginia City. An induced-polarization 

anomaly was recognized in an alluvium-covered 

area north of the Cornwall Knob. Core drilling 

to acquire more data on the geophysical anomaly 

was begun in August, and additional drilling is 

scheduled in the Cornwall Knob and Washington 

Hill areas to obtain geologic information and to 

compare geochemical data from depth with that 

obtained at the surface. Preliminary results 

suggest that the large areas of bleached rock are 

underlain by rock that ha undergone intense 

argillic alteration and that contains finely disseminated pyrite. (D. H. Whitebread, Menlo 

Park, Calif.) 

Positive aeromagnetic anomalie ranging from 

200 gammas to more than 400 gammas are associated with mafic parts of the Kate Peak 

Formation in the Flowery and Virginia Ranges 

of the district, and prominent magnetic maximums of 750 and 500 gammas, attributed to intrusive rocks, occur over Mount Davidson and 

Clark Mountain. Bleached rocks of the Alta and 

Kate Peak Formations and much of the Lousetown Formation are reflected by broad zones of 

low magnetic intensity. Unknown mineralized 

zones may occur in parts of the contact between 

Alta and Kate Peak Formations near anomaly 

sources and in Alta rocks on the north and west 

sides of the Mount Davidson intrusive mass. 

(W. E. Davis, Menlo Park, Calif.) 

NEW HAMPSHIRE 

Central and Northern New Hampshire 

Investigations and sampling continued on the 

mineralized rocks in central New Hampshire ex-
tending from the Gardner Mountain prospects 

along the Connecticut River northeast to the 

Milan mine in north-central New Ramp hire and 

beyond to near Errol in the northeast corner. 

The Milan mine, inactive but a former producer of copper and precious metals, is along the 

contact between volcanic rocks (Ammonoosuc 

volcanic belt) of Middle Ordovician age and 

granitic rocks of the Oliverian belt, of Middle or 

Late Devonian(?) age. Sulfide concentrations 

are associated with hornblende-rich dikes and 

very coarse-grained granitic pegmatites. 

Sulfides, mostly pyrite and chalcopyrite with 

minor sphalerite and galena, were found north 

and outh of the Milan mine in the Ellsworth 

Schist. However, no massive sulfides such as 

those at the Milan mine were seen in many prospects and surface exposures found in the area. 

A few very fine specks of gold were seen in 

gravels in a small stream at Stark. 

About 5 miles west of the Milan mine, Ordovician volcanic rocks are cut by the Conway Granite (Jurassic or Triassic). Contacts between 

granite and wall rocks are sharp, and small alt ration halo and spar e sulfides are seen only 

occasionally in the migmatites. 

Samples of Clough Quartzite (Silurian) from 

the eastern belt of outcrops on the east side of 

the Connecticut River in western New Hampshire 

contain 0.02 to 0.06 ppm gold. Samples from 

the western belt of outcrops were mostly ba1Ten. 

Pyritic schistose rhyolite near Gardner Mountain north of Woodsville in northwestern ew 

Hampshire contains as much as 6 to 14 ppm gold 

as well as traces of chalcopyrite. Samples from 

various copper prospects contain from 0.2 to 3 

ppm gold. 

The Gile Mountain Formation in northeast 

ew Hampshire showed only trace amounts of 

heavy metals. Sediments in northwest-flowing 

tributaries of Indian Stream contain small 

amounts of gold, but no gold has been found in 

southeast-flowing tributaries. (J. F. Harrington 

and J.P. D'Agostino, Washington, D.C.) 

Ossipee Lake Area 

Stream sediment sampling of the Ossipee 

Lake quadrangle, east-central ew Hampshire, 

has been completed and the data prepared for 

publication. Cold-citrate-soluble heavy metal 

analyses of 602 samples show four anomalies 

directly related to outcrops of quartz veins and 

24 

silicified fault breccia. Other anomalies not 

related to surface expr ssion of hydrothermal 

activity are also pre ent. The western partof 

the quadrangle, which is underlain by two large 

plutons of Conway Granite of Jurassic or Triassir 

age, has background values 60 percent higher 

than the eastern part. The silver-lead-zinc veiru 

in the quadrangle are beli ved to be related to 

the last stage of cry tallization of the Conway 

Granite, and the high backgrou nd over the 

granite may represent disseminations or many 

small concentrations of sulfide minerals. (D.P. 

Cox, Washington, D .. ) 

EW MEXICO 

Geochemical Anomalies. ie rra Cuchillo 

Geochemical anomalies of lead, molybdenum 

zinc, copper, tellurium, and barium in altere{ 

volcanic rocks in the Monticello Box area of th1 

northern Sierra Cuchillo, Socorro County, wen 

reported in U .. Geological Survey Circular 600 

In other areas molybdenum and tellurium an 

present in anomalous amounts wherever then 

is some other evidence of metallization; the1 

may be generally useful indicators of metalliza· 

tion in the region. (W. R. Griffitts, Denver Colo. 

ORTH CAROL! A 

Burke, Caldwell, and Catawba Counties 

During regional geochemical studie in w sten 

orth Carolina, more than 200 bulk samples a 

panned heavy mineral concentrates wer collecre 

from soil and aprolite. A few other ample e~~ 

collected from prospect dumps, and mor than 2(X 

from stream sediments. Most of the oil and sar 

rolite samples are from the vicinity of the hufoF 

gold mine in Catawba County, and many of tb 

stream sediment samples are from areas th& 

were mined for placer gold. Mineral occurrence ~ 

reported in the region were of no inter st. 1 

Visible gold was fourrd in 67 samples of hea1: ~ 

mineral concentrates from stream sedi men~ 

Most of these samples were collected in two ar~ 

near and south of the Shuford gold mine, and c 

Burke and Caldwell Counties near the comm 

corner for the Chestnut Mountain, Collettsvill! s 

Oak Hill, and Morganton North 7'h-minute quaH 

rangles. The Burke County-Caldwell Coun P 

area also contain anomalous niobium, tin, tun! 

sten, and molybdenum. Gold was al o found t 

concentrates from other parts of the area, be 

seldom in samples from three or more clos 
spaced localities Gold was seen in 51 concentrates of heavy minerals.from soil and saprolite; 

however, 48 of these were from near the Shuford 

gold mine. 

Some areas contain anomalous gold, niobium, 

tin, tungsten, molybdenum, lanthanum, and 

yttrium, and mineral analyses of the concentrates 

indicate areas containing rutile, monazite-xenotime, sillimanite, kyanite, garnet, zircon, and columbite-tantalite. However, no possibly commercial deposit of any element or mineral was found. 

Rutile occurs locally in crystals greater than onefourth of an inch across, but no significant concentration of rutile was found, and it is very doubtful 

that any minable concentrations of rutile are in 

the area. Local placer deposits are too small to 

be of interest. Gold, monazite-xenotime, columbite-tantalite, rutile, and zircon could possibly be 

byproducts of sand and gravel operations on the 

flood plains of streams, but a relatively easy and 

cheap methods to recover the heavy minerals 

would have to be developed. 

Studies and sampling of mined areas in the 

South Mountains of North Carolina and northward to lat. 36 ° . indicate that no minable deposits of gold or other minerals are in aprolite or 

bedrock in the area. Most of the mine either 

were placers or were located where water could be 

used to separate the hea y minerals from the unsolidated debri or aprolit . The few haft mine 

were mall. Miner report that the gold found 

in saprolite and b drock wa in thin quartz veins 

that rarely contained nough gold to mine unle 

several veins wer clo enough to mine a a ingle 

vein, a rare occurrence. No urfa e evidence of 

mineralized, rock was een. (J. W. Whitlow, 

1 Wa hington, D.C.) 

entral orth arolina 

1 Studies of the Carolina slate belt in central 

l North Carolina indicate that the Silver Hill-Gold 

Hill fault-shear zone is several miles wide and can 

ro be traced for many miles, probably northeast into 

Virginia and southwest into South Carolina. East 

: of this fault-shear zone, volcanic- edimentary 

t rocks of low-grade greenschist facies show both 

broad and minor open folds. West of the fault-

]: ~hear ~one, volcanic-sedimentary rock are cut by 

1u mtrus1ve rocks and are more highly metamor1 phosed, disturbed, and weathered than tho e to 

1 the east. 

It The gold and sulfide deposits are tructurally 

JCControlled and to some degree are related to spec25 

ific rock types. Mo t of the larger gold mines 

and prospects in North Carolina are in Mecklenburg Rowan, Cabarrus, and David on Countie . 

In these counties, the main mining districtsConrad Hill, Silver Hill, Gold Hill, and Georgeville- are west of the Silver Hill fault. Th ho t 

rock are sericitized and chloritized schi ts derived 

from sheared interbedded felsic and mafic volcanic-sedimentary rocks. The deposits east of 

the Silver Hill-Gold Hill shear zone lie in smaller 

shears that cut a equence of volcanic-sedim ntary rocks. In this area, the depo its are riche t 

where the hear zone cuts rhyolitic lay rs or tuffaceous mudstone; the Hoover-Jone -LaughlinCid(?) line of prospects is an example. 

During regional geochemical studie of residual 

soils, soils derived from rhyolitic rocks or tuffaceous mudstones were found to have the highe t 

content of copper, 60 to > 100 ppm, a well as 

traces of gold. One sheared gabbro lens within 

the Silver Hill-Gold Hill shear zone contains 0 to 

500 ppm copper along a strike length of about 

1 00 feet. Other gabbro lense or ill-like bodies 

contain < 0 ppm copper. (A. A. tromquist, 

Denver, Colo.) 

Moore County 

Sample from 245 localities in road outcrops, 

nine gold mines, and six pyrophyllit mine collected during reconnaissance geochemical tudies 

in Moore County, south-central orth Carolina, 

have been analyzed for gold. The area tudied 

was 1 miles long and 6 mile wide. Eighty samples from the gold mine contained 0.15 to 0.71 

ppm gold, and 46 samples from the pyrophyllite 

mine , a trace to 0.12 ppm gold. The highe t 

analysi , of thin quartz vein in a roadcut, was 2.4 

ppm gold, and only eight samples, all from gold 

mines or prospects, contained > 1 ppm gold. 

The entire area seem to show a low-grade gold 

anomaly. Locally, concentrations of gold in 

heared fel ic tuff and thin earn of vein quartz 

were rich enough to encourage small- cale mining 

in the late 19th century. Thick quartz veins are 

abundant in the area but generally contain little 

or no gold. Trace amounts of gold in the pyrophyllite zones produced small placer deposits 

which were pro pected before the discovery of the 

pyrophyllite. Total production from Moore 

County is unknown but probably small. (F. G. 

Lesure, Washington, D.C.) 
SO TH CAROLI A 

Geochemical studies in outh Carolina have 

been made in three areas- Me ormick County, 

Spartanburg-Union Counties, and the vicinity of 

Mount Rehovah, Fairfield County. Samples have 

been collected from stream sediments and saprolite to test both for the distribution of gold and 

other heavy metals over a fairly wide area and for 

extensions of mineralized ground near old mine . 

In McCormick County, reconnai ance geochemical sampling showed that gold- and copperbearing silicic to intermediate pyroclastic rock 

are associated with a mass of leucocratic quartz 

porphyry locally called metadacite. Geologic 

mapping and geochemical sampling along roads, 

supplemented by ground magnetometer traverses, 

indicate that the gold-bearing rocks at the Jennings mine extend along strike at lea t 1.6 mile 

and are 25 to 75 feet thick. The rock average 

0.03 ppm gold, and no high assays have been reported to date. Spectrographic analyses of tream 

alluvium, however, indicate that gold, barium, 

copper, lead, and tin may be distributed zonally 

around part of the metadacite. The association 

of manganese deposits with the gold mines 

near Graves Mountain in nearby Lincoln and 

Wilkes Counties, Ga., and the similarity of the 

mineralogy of the gold mines suggest that all are 

related to widespread mineralization in ilicic volcanic rocks. 

In Spartanburg and Union Counties, ampling 

of stream alluvium indicates that gold is widespread, and preliminary geologic mapping suggests that most of old mine workings are along 

an extensive shear zone. 

In Mount Rehovah area of Fairfield County, a 

belt of gold-bearing quartz-sericite schists is 

probably an extension of the Haile-Brewer-Lamar 

belt farther to the east. Geochemical sampling 

along road traverses will test this connection and 

possible further extensions to the west, where 

samples of well water of unusual mineral content 

have been reported. (Henry Bell , Washington, 

D.C.) 

OUTH DAKOTA 

Gold Deposits in Precambrian Rocks, Northern Black Hills 

Geologic mapping of Precambrian rocks in the 

Rochford district, 20 miles south of Lead, i nearly 

completed. The principal structure is a refolded 

anticlinorium in which the oldest rocks exposed 

are probably Ellison Formation of Hosted and 

Wright (1923), a quartzite unit that overlies the 

gold-bearing Hom stake Formation of Hoste: 

and Wright (1923) at Lead. Three rock units re-

. sembling th Homestake li e above the Ellison a

Rochford, one clo e to the quartzite in a slate 

quence that may correlate with the orthwesten 

Formation of Ho t d and Wright (1923) at L 

and two associated with graphitic schi t and elli~ 

soidal gre n ton . Th chi t, greenstone, am 

ch rt-cummingtonite rock of th Homestake-likt 

units coli ctively could b corr lative with t~ 

vagu ly defined Flag Rock Formation of Dodge 

(1942) at L ad. A at L ad, th chert-cummin 

tonite rock is gold-bearing locally. Also as 6' 

Lead, the gold seems to prefer plunging an · 

cline , but there are a few exc ptions. A fe1 

mineraliz d localities contain abundant pyrrhoti 

and are therefore anomalou ly magnetic. 

Of 465 ro k sample analyz d for gold, 221 ha1 

more than 0.02 ppm (the limit of detection); 

have more than 0.10 ppm; and 22 exceed 1.0 ppn 

The highest gold content found to date in an ou' 

crop amp! i 15 ppm. Thi sample cam fror 

a small plunging antic! in inch rt-cummingtoni 

rock. Six other ampl s from the same place h& 

more than 3.5 ppm. The principal structure! 

Rochford wa b I i v d previously to b an up ill< 

down yncline, but new d tailed mapping sho 

it to be an anticline similar to tho eat L ad at 

involving the same rocks, and thou h r folded ar 

rather complicated, it offer everal exploratic 

possibilities. For example, mo t mining to da· 

has been in the uppermost chert-cummingtonr 

unit. It now seems probable that on or two sill 

Jar units lie tratigraphically below and have 

been tested. Also, a dozen mildly min rali 21 

plunging anticline of good iz hould b tes 

to a depth, as they are in every way similar tot 

26' 

Homestake structures. 

Two diamond-drill holes tot st stratigra ~ 

concepts were put down in overturned folds in 

Precambrian. The fiJst, 3 miles southeast 

Lead, started in pillow lava (probably Flag Ro 

Formation), passed at about 1,000 feet into grar 

itic pyrrhotite schist, and then pass d into uno: 

relatable banded garnet slate at about 1,250 fe 

This hole was started at 5o and flattened to ~ 

so that the expected vertical depth was not 

tained. Total length of the hole was 1,850 ~ 

The pyrrhotite schist is arsenic-poor and theref! 

gold poor, as is typical in this region. The hig~ 

value is 1.0 ppm. The second hole was starteC 

the Ellison Quartzite in the principal anticline 
Rochford and was aimed at finding the underlying 

Homestake Formation. The hole started in slate 

and quartzite and ended in quartzite without penetrating below the Ellison. It was started at 85 ° 

and then flattened to 25 o so that the expected 

vertical depth again was not attained. Total 

length wa 1,500 feet. Pyritic rocks with pyrrhotite veinlets were cut, but all were low in arsenic 

and gold. The high est gold content wa about 

0.60 ppm. (R. W. Bayley, Menlo Park, Calif.) 

Ore Deposits in Paleozoic Rocks, orthern Black Hills 

Ore deposit in Paleozoic rocks of the northern 

Black Hills are being studied under a re earch 

contract with South Dakota School of Mines and 

Technology, Rapid City. These deposits have 

produced nearly 2 million ounces of gold and 4 million ounces of silver. The gold deposits are veins 

and replacement bodies of the telluride sylvanite,. 

(Ag,Au) Te2, in Missi sippian limeston or dolomite and am brian quartzite. Stratigraphic control is well establi hed in at least one district 

(Bald Mountain) and suspected in several others 

(Ragged Top, quaw Creek, Carbonate). 

Th tudy has volv d through thr e phas s: (1) 

compilation of all availabl data on or d po its, 

(2) photogeologic study of the north rn Black 

Hill to work out r gional tructure patterns, and 

(3) geologic mapping of elect d area , upplemented by geochemical inve tigations. Pha es 

1 and 2 have b n completed· photog ologic mapping proved to be un ati factory because of heavy 

vegetation and tructural complexiti . 

Mapping of about 100 quare mile at a cale of 

1:12,000 ha be n aimed at correlating mineralized 

horizons from di trict to district in order to predict 

likely new area for exploration. In addition to 

surface work, two diamond-drill hole , 1,215 and 

1,1 5 feet deep resp ctively, were put down north 

of Ragged Top Mountain to test tratigraphic and 

structural concept developed during mapping. 

(J.P. Gries, L. H. Shapiro, and J. K. Fisher, Rapid 

City, S.Dak.) 

UTAH 

ilver Reef District 

Preliminary study of the depo it of silver, copper, and uranium of the Silver Reef district at 

Leeds in Wa hington County indicates that they 

occur as disseminations, roll , and blankets, as do 

the uranium-vanadium depo it of the Colorado 

27 

Plateau. The principal silver mineral is cerargyrite in minute, nearly invisible grains or cru ts, 

and the concentration of silver varies with copper 

rather than with uranium. Although the ilver 

minerals are generally considered to be supergene, 

some possiblity exi t that they were deposited a 

silver ch lorides directly from sodium- and potassium-rich brines. Some light redi tribution of 

the silver may have occured along a few fault 

zones since the original deposition, but permeable 

zones, clay layers, and lenses of carbonaceous 

tra hare the main loci of ore depo ition. (A. V. 

Hey!, Denver Colo.) 

VERMONT 

Copper prospect were found in road outcrop 

and a quarry in northwe t Vermont almost on the 

border of Canada, between Berk hire and East 

Berkshire. Stringers of chalcopyrite occur in an 

area of mafic schists and greenstone . ampling 

over minabl e width showed only 50 ppm copper 

but additional work may find higher grade ore . 

Analyses howed only traces of gold and silver. 

ample of pelitic schists of the Moretown Formation were collected in seven roadcuts in southeast Vermont near Dover. Th amp! how d 

from 50 to 3,000 ppm nickel and no platinum. 

Additional work will be needed to determine the 

extent of nickel mineralization. (J. F. Harrington 

and J. P. D'Agostino, Washington D. C.) 

VTRGI lA 

Gossan Lead 

The Great Go an Lead is a major mineralized 

ulfide zone near Galax in Carroll County. The 

Lead con ists of a series of elongated sulfide lenes extending over a strike length of 17 miles; 

they are enclosed in Precambrian schist and 

gnei s and generally conform to the schistosity 

of the wallrock. Recurrent faulting along the 

hear zone may have reopened fractures for ore 

olutions which have partly replaced breccias and 

conglomerate . Mineralization ranges from 

massive to cattered sulfides in quartz, schist, 

and aplite. Gangue material contains hydrothermal silicate mineral uch as biotite and 

amphibole. Some fractures and pebble surfaces 

are replaced by ore minerals. Width of ore 

lenses range from a few feet to about 80 to 100 

feet in parts of the Betty Baker segment. Inferred reserves are at least several tens of millions 

of tons. · 
The Gossan Lead was mined only for supergene 

copper sulfate prior to World War I. Later, until 

shortly after World War II, it was exploited for 

manufacture of ulfuric acid and iron ore that 

remained after roasting. Principal sulfide 

minerals are pyrrhotite, pyrite, chalcopyrite, and 

sphalerite, with a little galena. Copper zinc, 

and lead were not recovered, but the e metals 

may be important byproducts if this large deposit 

is again worked for sulfur and iron. Preliminary 

samples a long exposures in old workings that 

how primary ulfides gave the following analyses: 

Copper ______ _ _ _ _ _ _ 3,000-20,000 ppm. 

Gold _______________ one-trace. 

Lead _______________ 500-1,000 ppm. 

Molybdenum ________ 5-20 ppm. 

ickeL ____________ 0-200 ppm. 

Silver ______________ 0- 10 ppm. 

Sulfur ______________ 25 percent. 

Zinc ________________ 100- 15,000 ppm. 

(J. F. Harrington and J.P. D'Agostino, Washington, D. C.) 

Reconnaissance Geochemical tudies, outhwe ·t Virginia 

Reconnai sance geochemical inve tigations in 

outhwest Virginia have revealed four area that 

merit additional study. 

In Floyd County, samples taken from roadcuts 

near the Vest nickel mine contain 0.20 ppm gold, 

and samples of low-grade arsenic ore from the 

Old Arsenic mine contain 0.30 ppm gold. Ore 

and waste material have been largely removed 

from the Ve t pro pect and the pro pect pits are 

filled with water. Some ore and large dump 

are still present at the Old Arsenic mine, where 

about 11h underground acres have been mined. 

I n addition to ar enic, material on the dumps 

contains 1,000 to 3,000 ppm copper, 100 to 1,000 

ppm t in, 6 to 20 ppm silver, and 100 to 500 ppm 

bismuth. 

umerous barren-appearing quartz vein occur 

in Floyd County. Of the few sampled, none contained gold. One sample of massive pyrrhotite 

with minor chalcopyrite from the Toncrae mine 

in western Floyd County assayed 0.06 ppm gold. 

In Pulaski County along Reed Island Creek 

j ust west of Boom Fu rnace, brecciated Shady 

Dolomite (Cambrian) contains a few small disseminated pyrite cubes. Three assays of one 

sample gave 0.07, 0.10, and 0.40 ppm gold; the 

other sample was barren. The rocks are probably 

within the Gleaves Knob-Popular Camp overthrust 

zon , a part of th Great Go an Lead overthrust 

belt about 5 mile north of the nort hern part of 

the Gossan Lead. 

In Gray on ounty about 9 mil due west of 

Galax, phyllite of the Lynchburg Formation (Precambrian) i in contact with th Grayson Granodiorite Gnei . The area is about 10 miles 

south we t of the Great Gossan Lead and on the 

am structural trend. A sampl e of siliceous rock 

with minor ulfid s from th contact zone contained no gold, but a barren-app aring phyllite 

sample from near the contact zone assayed 0.60 

ppm gold. 

28 

In Gray on County about 6 mile southwest of 

Galax, barren-appearing quartz tringers cut 

phyllitic bedrock of the Lyn ·hburg Formation 

(Pre ambrian). The locality is about 200 yards 

north we t of pro pect tr nches of the Davis manganese mine, and the area is about miles south 

of the outhern most part of the Great Gossan 

Lead. The only amp! of vei n quartz collected 

a ayed 0.20 ppm gold. Other amples were from 

the immediate mine area; most contained man· 

gan e wad, but non had any gold. (J.P. 

D'Agostino, Washington, D. .) 

Virgilina District, Virginia and orth arolina 

A reconnaissance geochemical study of the 

Virgilina district in Virginia and North arolina 

was started in 1968. A preliminary geologic 

map by Lynn Glover of the U.S. Geologi cal 

Survey and other published geologic maps were 

used as guides in collecting 230 amples of 

mineralized and barren rock in an area about ~ 

miles long and 14 miles wide. Only four of the 

first 40 samples contain detectable gold. These 

contained 0.02 to 0.08 ppm gold and came from 

the vein and adjacent wallrock of the Durgy 

copper mine in Person Co unty, N. C. Other 

samples remain to be analyzed. (F. G. Lesure. 

Washington, D. C.) 

WYOM ING 

Platinum Metals, Medi cine Bow Mou ntains 

An area of 100 sq mi or more in t he east· 

central part of the Medicine Bow Mountains 

Al bany and Carbon Counties, has been identifili 

as a region relatively rich in platinum metals anl 

sil ver. Field studies and analytical data well 

reported in U.S. Geological Survey Circul ar 6~ I 

(published in 1969). The waste dump at t he Nev 

Rambler mine, the principal mine in the area, ~ 
estimated to have 50,000 tons of material containing 0.3 percent copper, 7 ppm silver, 1 ppm 

platinum plus palladium, and 0.7 ppm gold. The 

platinum and silver content of samples from the 

entire region appears to be an order of magnitude 

higher than the estimated average crustal abundance. (P. K. Theobald, Jr., and C. E. Thompson, 

Denver, Colo.) 

Quartzite Conglomerates, Northwest Wyoming 

Reconnaissance sampling of quartzite conglomerates from seven formations of Late Cretaceous 

to Miocene age was completed in 1968. Analytical data on more than 10,000 samples are now 

being compiled. These data supplement the 

preliminary report published as U.S. Geological 

Survey Circular 541 in February 1967 and will 

probably show somewhat lower average gold 

contents in most of the formations. An exception 

may be the Pass Peak Formation of Eardley 

and others (1944) which crops out southeast of 

the southern part of the Pinyon Conglomerate. 

Higher values than those previously reported 

have been found in some Quaternary deposits 

derived from the onglom rat s, parti ularly 

along Pacific and Lava Creeks. 

Samples from some localities of the Wind 

River Formation, in addition to having gold, 

contain appreciable quantities of rare earths 

thorium, uranium, zirconium, and other metals: 

The following analysis is from the South Fork 

of Warm Spring Creek, where a sluice concentrate 

contained 5 ppm gold: 

Percenl. 

Ti _ _ _ _ _ _ _ _ _ _ _ _ 3.0 

Ce _ _ _ _ _ _ _ _ _ _ _ _ 5.0 

La ____________ 3.0 

Th _ _ _ _ _ _ _ _ _ _ _ _ 1.5 

u -- -- -- ---- -- .1 

Zr- ___________ 10.0 

Sluice concentrates from gravels of Pacific 

Creek carry as much as 50 ppb platinum. Spec-

' trographic analyses on gold from Pacific Creek, 

· Box Creek, and Green River (near Big Piney) 

I show as much as 30 ppm palladium. 

t Virtually all the gold is smaller than 0.3 mm in 

·' maximum dimension. Removal of cobbles 

)' pebbles, and coarse sand by screening increas~ 

' the gold content of the remaining material by a 

t factor of 2 to 5, as is illustrated by the following 

29 

typical example on gravel from Lava Creek (gold 

price, $35 per oz): 

Value of gold in 1 cubic yard of in-place 

gravel----------------------------$0.17 

Value of gold in 1 cubic yard of -60 

mesh sand __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ .54 

(J. C. Antweiler, Denver, Colo.) 

Information bearing on the source and provenance of the quartzite-cobble conglomerates 

of the Harebell Formation (Upper Cretaceous) 

and Pinyon Conglomerate (Paleocene) is being 

analyzed. Paleocurrent directions deduced from 

crossbedding, imbrication, and roundstone diameter indicate sources to the west and northwest of Jackson Hole. Pebble counts and thinsection studies of clasts indicate a quartzitevolcanic-sedimentary source terrane. The Wyoming conglomerates bear numerous petrographic 

similarities to the Divide conglomerate lithosome 

of Ryder (1967) of the Beaverhead Formation, 

west of Jackson Hole. Paleocurrent directions 

indicate that the Divide conglomerate lithosome 

was derived from the southwest. It is likely that 

all these quartzite-cobble conglomerates were 

derived from the present vicinity of Belt Supergroup quartzite in Idaho. 

Study of nonopaque heavy minerals from 26 

samples of Harebell Formation and Pinyon Conglomerate from Jackson Hole, and of 12 samples 

from the time-equivalent Lance and Fort Union 

Formations on the west flank of the Bighorn 

Basin, suggests that rocks in the two basins were 

derived from different sources. In particular, 

monazite and epidote are more abundant in the 

Jackson Hole rocks. Petrographic study of 

quartzite cobbles in these rocks also suggests 

different sources; cobbles containing abundant 

feldspar and with xenoblastic mica are common 

in Jackson Hole rocks but do not occur in Bighorn Basin .rocks. (D. A. Lindsey, Denver, Colo.) 

MARINE STUDIES 

GEOLOGY OF THE BERING AND CHUKCID SEAS, ALASKA 

A broad study of the geology, heavy minerals, 

glaciology, and bathymetry of the Bering and 

Chukchi Seas, in particular the region off the 

Seward Peninsula around Nome, is being made 

through a cooperative research contract with the 

University of Washington, Seattle, Wash., and 

also in cooperation with the U.S. Coast and 

Geodetic Survey, Environmental Science Services 

Administration, U.S. Department of Commerce. 
Oceanographic studies have been made on board 

the University of Washington research vessel 

Thomas G. Thompson and the Coast and Geodetic 

Survey ships Surveyor and Oceanographer. 

Studies Around ome, Seward Peninsula 

The richest offshore gold concentrations found 

to date in the northern Bering Sea are in relict 

coarse sediments near Nome. Relict sediments 

were found to extend along the shore however ' ' as far as Solomon, some 30 miles east of Nome 

and traces of gold were found throughout th~ sampled area. Sparse reconnaissance sampling 

defined a promising area for further exploration 

offshore between Cape Rodney and Cape Wooley, 

30 to 40 miles west and northwest of orne; this 

area may be one in which shallow bedrock 

extends exceptionally far offshore, and the gold 

content may reflect a local source of bedrock 

mineralization. 

Seismic records obtained along closely spaced 

lines in Norton Sound off Nome show that bedrock has only a relatively thin cover of sediments 

west of Nome and that bedrock crops out as 

much as 2 miles offshore. Bedrock deepens 

eastward and directly off N orne is covered by as 

much as 500 feet of sediment. Buried terraces 

seem to be present at depths of 120 and 1 0 feet 

below sea level. 

Evidence from pollen and Foraminifera recovered from drill holes in Norton Sound 2 to 3 

miles off Nome indicates that marine beds of 

late Miocene or early Pliocene age are covered 

by less than 50 feet of younger sediments. A 

buried beach 50 feet below sea bottom and 70 feet 

below sea level may mark the inner limit of the 

Miocene beds. 

A recently competed bathymetric map of an 

a.rea 30 to 40 miles west of Nome shows positiOns of submerged shorelines at depths of about 

35 and 75 feet, as well as former courses of the 

Sinuk River and a linear scarp (fault?) southeast 

of Sledge Island. The area around this scarp 

may constitute a new exploration target, as 

faults associated with similar scarps in the Nome 

area are mineralized. The map is at a scale of 

1:20,000, with a 2-foot contour interval. 

Bottom Sampling in Northern Bering Sea 

About 700 bottom samples have been collected 

from the northern Bering Sea and analyzed for 

their gold content; about half of these were collected in a closely spaced grid along the coast of 

southwestern Seward Peninsula, and the re. 

mainder were collected elsewhere. Nearly even 

sample contains traces of gold, reflecting th; 

high background of gold that appears to be 

ch~racter~stic of the northern Bering Sea. Coarse, 

rehct sediments were found in several areas in· 

eluding two large patches that extend north~aro from St. Lawrence Island. The gold content of 

these coarse sediments is commonly higher that 

the background values in finer grained sedi. 

ments, and the coarse sediments merit mon 

detailed sampling to define areas likely to con· 

tain economic placer deposits. Coarse botton 

sediments near and north of western St. Law 

renee Island contain small quantities of nativf 

copper. These sediments appear to consist o! 

glacial morainal material derived from thf 

Siberian mainland, and the presence of nativf 

coppe: may point toward undiscovered coppe1 

deposits on the Chukotsk Peninsula of nor ~ 

eastern Siberia. 

Fine-grained gold in amounts ranging frorr 

0.03 to 0.10 ppm has been identified in firn 

muddy sands. Although the particle size of thi 

gold is as yet unknown, the partie! s app ar tt 

be hydraulically equivalent to quartz grains ~ 

coarse silt or fine sand size (0.05 to 0.01 mm). 

Glacial St•dies, Bering Sea 

Glacial drift has been identified in dredge halli 

from the Bering Sea between St. Lawren& 

Island and Bering Strait, and the nature of ttr 

material has been confirmed by electron mic · 

photographs of surface textures of sand grain: 

In addition, new information on the extent an 

stratigraphic position of the drift has esul~ 

from study of high-resolution seismic reflectia 

profiles. The drift was derived from highlanc 

on Chukotsk Peninsula and Seward Peninsub 

both of which have deposits of gold and til 

Thus, recognition of the extent of drift delimii 

areas within which concentrations of th e~ 

metals may occur along submerged beaches an 

stream channels. 

Seismic records indicate that the edges oft~ 

separate drift sheets can be recognized off tt 

coast of Nome. One sheet centers roughly o 

Nome, and its western edge crosses the bear 

about 7 miles west of Nome. The east edge c 

the second sheet crosses the beach near tt 

30 
same place and then extends westward parallel 

with the beach and about 3 miles offshore. 

General Geologic Studies, Bering Sea 

Deep penetration seismic profiles in the Bering 

Sea have revealed a series of basins containing 

as much as 7,000 feet of Neogene sediments. 

The size of the basins, the nature of their sediments, and the presence of minor broad folds 

suggest the possibility of accumulations of petroleum. 

The cooperative project of the Geological 

Survey and the Environmental Science Services 

Administration for geophyscial studies and 

sampling in the Bering Sea was carried out between July 24 and August 2. During this cruise, 

214 grab samples and 38 box core samples were 

collected at 201 stations along a track 921 nautical miles long. (D. M. Hopkins, A. R. Tagg, 

and C. H. Nelson, Menlo Park, ·calif.; D. A. 

McManus, Seattle, W asbington.) 

GULF OF ALASKA CO TI ENTAL SHELF 

The geology and possible heavy mineral potential of the nearshore Gulf of Alaska are being 

studied through a cooperative research contract 

with the Univer ity of Ala ka. Fi ldwork i 

being done on the oceanographic research ve el 

Acona. Cruises ba ve been made off Yakutat 

Bay, southern Kenai Peninsula, and Kodiak 

Island. Yakutat Bay is in an area of black sand 

beaches that have produced some gold and 

platinum. 

Samples collected around Yakutat at 135 localities using the Shipek grab sampler show that 

most of the uncon olidated sediments are muds. 

Only 36 samples contained material coarser than 

silt (0.062 mm). Small amounts of gold were 

found in nine samples. 

Seismic profiling between Cross Sound, west 

of Juneau, and Yakutat Bay has not revealed 

any submerged beaches, but the outer limit of 

glacial moraine, which may be a site for heavy 

mineral accumulation, was recognized. Southeast of Yakutat Bay the outer margin of the 

continental shelf has a well-developed anticlinal 

structure and good petroleum potential. 

In the Nuka Bay area of southern Kenai Peni~sula, acoustical ubbottom profiling and samplmg were done in 1968, isopach maps were 

made for bottom sediments, and sedimentation 

rates were determined. The bay is a recently 

31 

deglaciated fiord, and the area around the bay 

bas rich gold deposits which are now being 

eroded. Local concentrations of gold may have 

formed during the present and earlier glacial 

cycles, and the study is aimed at discovering 

how gold is caried at present and where it is deposited. No gold has been found to date in 28 

analyzed samples of sediment pockets in the 

fiord. (R. E. Von Huene, Menlo Park, Calif. and 

F. F. Wright, Fairbanks, Alaska) 

HEAVY MINERALS, I NER CO TINE TAL HELF OF 

WASHINGTO 

Preliminary studies of the inner continental 

shelf off Washington have been as part of a 

cooperative research contract with the University of Washington at Seattle. 

Two hundred grab samples have been collected using VanVeen and Shipek samplers. In 

the area around Cape Flattery, 35 samples contained from 0.3 to 5.5 percent of heavy mineral 

(sp gr > 3.18), with one sample containing 40 

percent. Opaque minerals constitute about 15 

percent of the total heavy minerals. No data 

are available yet on metal content. 

Heavy mineral content of samples elsewhere 

in the sampl ed ar a i generally < 5 perc nt; 

orne higher concentrations occur northwest of 

Grays Harbor. Anal y es of 29 randomly selected sample indicate a very low background 

content of gold, less than 0.001 ppm; only one 

sample contained as much as 0.01 ppm. (P. D. 

Snavely, Menlo Park, Calif., and D. A. McManus, 

Seattle, Wash.) 

GEOLOGY OF THE !XES RIVER DRAI AGE, OREGON 

The Sixes River enter the Pacific Ocean just 

north of Cape Blanco and directly east of the 

most extensive and highest concentration of gold 

and other heavy minerals found thus far on the 

Oregon continental shelf. The river appears to 

be a major source of heavy minerals and therefore a detailed study of its drainage basin is 

being made through a research contract with 

the University of Oregon at Eugene. 

Bedrock in the drainage area has been mapped, 

and stream sediments at about 20 stations have 

been sampled in detail and analyzed chemically 

and petrographically. The work i aimed at 

determining the sources of heavy minerals in the 

drainage, the nature of their fluvial transport, 

and the amount and physical characteristics of 

gold and platinum contributed by the river. 
The major source rock appears to be the Galice 

Formation (Jurassic) and associated small intrusive bodies. The Galice Formation consists 

mainly of slaty to phyllitic mudstone, siltstones, 

and sandstones. The intrusives, emplaced during 

the Late Jurassic Nevadan orogeny, are mainly 

diorites and quartz diorites. The Galice, where 

it is free of intrusives, and the larger masses of 

dioritic intrusive rock are less important gold 

sources. Conglomerate of Cretaceous age, which 

overlies the Galice Formation and associated intrusives, is apparently not a major contributor of 

second-cycle gold. Rocks of post-Nevadan 

Jurassic age, the Colebrooke Schist and associated ultramafic rocks and Cretaceous and Tertiary shales and sandstones are minor to negligible 

contributors of gold. (Sam Boggs, Jr. and E. M. 

Baldwin, Eugene, Ore.) 

HEAVY MI ERALS, OREGO CO Tl ENTAL SHELF 

The mineralogy and heavy metal potential of 

sediments on the continental shelf of Oregon 

are being studied under a cooperative research 

contract with Oregon State University at 

Corvallis. Two cruises totalling 1 days were 

made on the research vessel Cayu e, between 

Tillamook Bay and the California border. 

Thus far in the project, 3 box cores, 23 piston 

cores, 16 rock cores, 10 pipe or rock dredge hauls, 

and 30 Shipek samples (at 22 localities) were 

taken, and 75 deep sea camera stations were 

occupied, most at depths ranging from 16 to 

200 m. 

Studies of heavy mineral mineralogy of the 

four principal drainage basins contributing sediment to the continental shelf (Klamath - South 

Coast, Umpqua - Mid Coast, North Coast, and 

Columbia), of beach sands at 70 localities, and of 

relict sands on the continental shelf have shown 

that the predominant direction of sediment 

transport along the Oregon coast has been northward, both in the past and at present. The 

thickness of unconsolidated sediments on the 

southern part of the shelf averages about 20m, 

and maximum thickness is about 40 m. 

Study of heavy mineral concentrates has shown 

that from 3 to 59 percent of the heavy fraction 

consists of black opaque minerals, of which more 

than half locally is a magnetic mineral, magnetite or ilmenite. Magnetic anomalies were 

recognized off the mouths of the Rogue and 

Sixes Rivers in 1967, and therefore about 320 km 

of magnetometer track lines wer run in 1968 t1l 

check these areas and to test several new areas. 

New anomalies were found off the Pistol River . l 

south of Rogue River, at a water depth of 43 m, 

the same depth a the large anomalous area off 

Rogue River. The ocean floor at the Pistol River 

anomaly has a high concentration of heavy 

minerals. 

A number of anticlines and synclines in Mesozoic and Cenozoic rocks underlying unconsolid· 

ated sediments trend roughly parallel to the 

present coastline between the Rogue River and 

Cape Blanco. The major folds still have slight 

topographic expression and may have controlled 

transport and accumulation of heavy minera~ 

on the shelf during the Holocene; this possible 

structure control is being studied. 

The distribution of gold in surface sediments 

on the Oregon continental shelf was reported in 

U.S. Geological Survey Circular 587. In sum· 

mary, concentrations of 50 ppb or more were 

found at three places between the Coquille and 

Rogue Rivers; the largest area of gold concentra· 

tion, 15- 20 q mi, was off Cape Blanco. Gold 

occurs in black sands believed to be relict beach 

placer formed during a previous low stand of 

the sea. Concentrations of black sand have al 

been found at the edge of the continental shelf; 

the finding of black sands at such depth and at 

such a distance from shore extends considerably 

the range of potential submarine placer deposit: 

on the continental shelf. (H. E. Clifton, Menlo 

Park, Calif., and L. D. Kulm, Corvallis, Ore.) 

32 

GEOLOGY AND HEAVY MINERALS, CONTINENTAL HEIJ. 

ORTHER CALIFOR lA 

The geology and heavy metal potential of thr 

continental shelf of northern California is under 

investigation through a cooperative researct 

contract with Scripps Institution of Ocean· 

ography, La Jolla, Calif. The oceanographit 

vessel Oconostota is participating in the work ' 

Gold distribution on the sea floor off thf 

Klamath Mountains was reported in U.S. G!lfr ' 

logical Survey Circular 605. Analyses of : • 

samples of surficial sediment in this area sho9 E 

that the background gold content is about 0.1 1 

ppb. Four anomalous areas, as much as ~ I 

square kilometers in extent, have sediment coli" ~ 

taining 10 ppb or more of gold; the highest goll ~ 

content found to date is 390 ppb. 

Analysis of these samples has revealed i a 
hitherto unrecognized relationship between gold 

and heavy minerals. Contour maps showing 

percentages, in a group of samples, of minerals 

heavier than a given heavy liquid were prepared 

for several heavy liquids. These maps indicate 

that maxima for the various liquids are displaced systematically from the gold maxima, 

with the maxima for the heaviest liquid being 

closest to the gold maxima. The heavy-mineral 

trends may be useful in directing sampling toward areas of highest gold concentration. 

An area of about 6 square degrees has been 

mapped on the continental margin off northern 

California during a 1-month cruise of the 

Ocono tota. Some 4,100 km of subbottom 

profiling were run, and 33 dredge samples, including four large sand samples for platinum 

analysis, were collected. 

Basement rock of a submarine plateau 25 km 

wide that lies west of the continental shelf off 

northermost California at depths of 800- 1,000 m 

is of Eocene age. Dredge samples containing 

late Eocene Foraminifera were taken 75 km offshore. This finding approximately doubles the 

known width of possibly petroleum-bearing 

Tertiary rocks at the contin ntal margin. (G. W. 

Moore and E. A. Silver, La Jolla, Calif.) 

Ml ERALOGY OF 0 Tl ENTAL- HELF EDIMENT • 

0 THER CALIFOR lA 

The mineralogy of continental-shelf s diments 

off southern California is being investigated by 

scienti ts of the University of outhern California under a research contract. The oceanographic re earch v s el Vel ro IV is being 

used. 

Analyses are being made of the light and 

heavy mineral fractions of and and ilt in 57 

samples of sediments being carried by all the 

main riv rs between the Mexican border and 

Point Conception, a distance of about 220 mile . 

Shallow-water sediments off Santa Ro a Santa 

Cruz, and Santa Catalina Island als; were 

sampled. Work will continue to e tabli h the 

sedi~entolog~cal regime of the region - proven_ance of sed1 ments, effects of weathering on 

mmeral components in each river, dispersal 

patterns, and so forth. Preliminary results show 

· that t~e percentage of heavy mineral (sp gr 

> 2.9) m stream sediments increases from less 

than 1 percent between Jalama and Carpinteria 

1 at the northwest end of the sampled area, to 2 

33 

percent between Carpinteria and Palos Verdes, 

and to 6 or 7 percent southeast of Palos Verde ; 

the highest heavy mineral content is 25 percent. 

Neither river nor beach sediments appear likely 

to contain sizable concentrations of heavy minerals. Further work will be needed to evaluate 

the heavy mineral potential of shelf sediments. 

(D. S. Gorsline, Los Angeles, Calif.) 

HEAVY Ml ERALS, MIDDLE ATLANTIC CONTINE TAL 

HELF 

Heavy minerals on the continental shelf of the 

middle Atlantic coast are being studied under a 

research contract with Duke ni versity. The 

oceanographic research vessel Ea tward is 

being used. This part of the continental helf i 

characterized by low sedimentation rate, low 

proportions of and-sized or coarser sediment 

and abundance of calcium carbonate. 

Samples collected by box dredge at more than 

2,000 sites on the continental shelf between Cape 

Hatteras, . C., and Cape Roman, S. C., and 

another 200 ample collected from dunes and 

beaches in North and South Carolina and in 

Virginia are being studied. 

Heav min raJ con ntrat s from 60 amp! 

of continental-shelf edi ments and from eigh t 

beach ands have been analyzed for heavy metal . Most analyse for gold show < 0.1 ppm, 

but one from the outer helf off Cape Lookout, 

. ., contain more than 2 ppm. (0. H. Pilkey, 

Durham, . .) 

11 CELLA ' EO . T UDIE 

il"er ontent of Foraminifera-Bearing Deep Ocean Sediments 

The silver content of 80 Foraminifera-bearing 

samples from three cores collected at high latitudes in the South Pacific, of 12 grab samples 

from the continental slope and rise off the North 

Carolina coast, and of 30 sample of carbonate 

ediments from the continental rise and Sigsbee 

Abyssal Plain in the Gulf of Mexico has been 

determined. The silver content, several parts 

per million , is more than an order of magnitude 

higher than previously reported amounts in deep 

ocean ediments. The new analyses a! o suggest that the content of silver, copper, zinc, and 

lead in these deep ocean sediments varie directl y with water temperature condition . 

Further analyses are being made on samples 

from deep parts of the Atlantic Ocean. (H. L. 

Berryhill and C. W. Holmes, Corpus Chri ti, Tex.) 
REFERENCES CITED 

Dodge, T. H., 1942, Amphibolites of the Lead area, northern Black Hills, South Dakota: Geol. Soc. America 

Bull. , v. 53, no. 4, p. 561-583. 

Eardley, A. J. , and others, 1944, Hoback-Gros VentreTeton [Wyo.] Field Conference: Michigan Univ. Geol. 

map, scale about 1 inch to 2 miles, a nd tectonic map, 

scale 1 inch to 4 miles with sections, 2 sheets. 

Gilbert. C. M., hristensen, M. N., Al-Rawi, Yehya, and 

Lajoie, K. L., 1968, Structural and volcanic history of 

Mono Basin, California-Nevada, in R. R. Coa ts, R. L. 

Hay, and C. A. Anderson, eds., Studies in Volcanology : 

Geol. Soc. of America Memoir 116, p. 275-329. 

34 

Hosted, J. 0 . and Wright, L. B., 1923, Geology of t

Home take ore bodies and the Lead area of Sou

Dakota: Eng. Mining Jour. Press, v. 115, no. 18 and 

p. 783- 799, 836-843. 

Post, E. V., Lehmbeck, W. L., Denn n, W. H., and Nowla

G. A., 1967, Map of southeastern Maine showing heav

metals in stream sediments: U .. Geol. Survey Miner

Inv. Field Studies Map MF-301. 

Ryder, R. T., 1967, Lithosomes in the Beaverhead Form

tion, Montana-Idaho : apr liminary report, i n L. 

He nde rson, C. W. pe nce r, a nd W. B. Hopkins, ed 

Montana Geol. Soc. Guid book, 1 t h Ann. Field on

Centennial Basin southw st Montana, p. 63-70. 
INSTRUCTIONS FOR ORDERING U.S. GEOLOGICAL SURVEY PUBLICATIONS LISTED IN 

SECTION "PUBLICATIONS" 

Maps: Order from the Washington Distribution 

Section, U.S. Geological Survey, 1200 South 

Eads Street, Arlington, Va. 22202, or from the 

Denver Distribution Section, U.S. Geological 

Survey, Federal Center, Denver, Colo. 80225. 

Prepayment by check or money order in U.S. 

funds, payable to the Geological Survey, is required. 

Circulars: Free on request to the U.S. Geological Survey, Washington, D.C. 20242. 

Professional Papers: Order from the Superintendent of Documents, Government Printing 

Office, Washington, D.C. 20402. Prepayment 

by check or money order in U.S. funds, payable to the Superintendent of Documents, is 

required. 

On all mail orders, includes series and number 

(that is, Map MF-301 ; Professional Paper 

600-B), and title. Please print complete mailing 

address plainly (zip code required). 

Main U.S. Geological Survey centers: 

Main Office- Washington, D.C. 20242 

Rocky Mountain Center-Denver Federal 

Center, Denver, Colo. 80225 

Pacific Coast Center-345 Middlefield Road, 

Menlo Park, Calif. 94025 

35 G P 0 875 · 6 60