Geology, Geochemistry, and Uranium Favorability 

of Tertiary Rocks in South-Central Alaska 

A. Geology, Geochemistry~ and Uranium Favorability of the 

Tertiary Kenai Group in the Susitna Lowlands at the 

Northern End of Cook Inlet Basin, Alaska 

:B. Geology, Geochemistry, and Uranium Favoraoility .of 

Tertiary Continentai Sedimentary Rocks in the 

Northwestern. Part of the Cook Ialet Area, Alaska 
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Geology, Geochemistry, and Uranium Favorability 

of Tertiary Rocks in South-Central Alaska 

A. Geology, Geochemistry, and Uranium Favorability of the 

Tertiary Kenai Group in the Susitna Lowlands at the 

Northern End of Cook Inlet Basin, Alaska 

By Kendell A. Dickinson 

B. Geology, Geochemistry, and Uranium Favorability of 

Tertiary Continental Sedimentary Rocks in the 

Northwestern Part of the Cook Inlet Area, Alaska 

By Kendell A. Dickinson, John A. Campbell, and William F. Dula, Jr. 

U.S. GEOLOGICAL SURVEY BULLETIN 2098 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1995 
U.S. DEPARTMENT OF THE INTERIOR 

BRUCE BABBITT, Secretary 

U.S. GEOLOGICAL SURVEY 

Gordon P. Eaton, Director 

Published in the Central Region, Denver, Colorado 

Manuscript approved for publication May 12, 1994 

Edited by Judith Stoeser 

Photocomposition by Shelly Fields 

Graphics prepared by Shelly Fields and Carol Quesenberry 

For sale by U.S. Geological Survey, Information Services 

Box 25286, MS 306, Federal Center 

Denver, CO 80225 

Any use of trade, product, or firm names in this publication is for descriptive purposes only and 

does not imply endorsement by the U.S. Government. 

Library of Congress Cataloging-in-Publication Data 

Dickinson, Kendell A., 1931-

Geology, geochemistry, and uranium favorability of Tertiary rocks in south-central 

Alaska. 

p. em. - (U.S. Geological Survey bulletin ; 2098) 

Includes bibliographical references. 

Contents: A. Geology, geochemistry, and uranium favorability of the Tertiary Kenai 

Group in the Susitna Lowlands at the northern end of Cook Inlet Basin, Alaska I by Kendell 

A. Dickinson- B. Geology, geochemistry, and uranium favorability of Tertiary continental sedimentary rocks in the northwestern part of the Cook Inlet area, Alaska I by 

Kendell A. Dickinson, John A. Campbell, and William F. Dula, Jr. 

1. Geology, Stratigraphic-Tertiary. 2. Geology-Alaska-Cook Inlet 

Region. 3. Uranium ores-Alaska-Cook Inlet Region. I. Campbell, John A. (John 

Arthur), 1930- . II. Dula, William Frederick. III. Title. IV. Series. 

QE75.B9 no. 2098 

[QE691] 

557.3 s-dc20 94-25919 

[553.4'932'097983] CIP 
Geology, Geochemistry, and Uranium Favorability of the 

Tertiary Kenai Group in the Susitna Lowlands at the 

Northern End of Cook Inlet Basin, Alaska 

By Kendell A. Dickinson 

URANIUM FAVORABILITY OF TERTIARY ROCKS, SOUTH-CENTRAL ALASKA 

U.S. GEOLOGICAL SURVEY BULLETIN 2098-A 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1995 
CONTENTS 

Abstract ........................................................................................................................... At 

lntr<Xluction......... ... .. .. ..... ... .. .. ... .. ... .. .. ... .. ... .. .. ... .. ... .. .. ... .. ... .. .. . .. .. ... .. .. ... .. ... .. .. ... .. ... .. .. ... .. 1 

Geology........................................................................................................................... 3 

Tertiary Sedimentary Rocks .............. ... .. .......... .................................... .... ... ................... 3 

Meth<Xls........................................................................................................................... 6 

Statistical Analysis.......................................................................................................... 7 

Clay Minerals.................................................................................................................. 11 

Uranium Favorability ...................................................................................................... 11 

References Cited............................................................................................................. 13 

Appendix I -Chemical and Mineralogical Data for Samples of the Tyonek(?) and 

Sterling(?) Formations of the Tertiary Kenai Group .................................................. 15 

Appendix 2-Measured Sections of the Tyonek(?) and Sterling(?) Formations of 

the Tertiary Kenai Group............................................................................................ 18 

FIGURES 

1. Index map of south-central Alaska showing study area.............................................................................................. A2 

2. Map showing geology of the Susitna Lowlands area and locations of measured sections......................................... 4 

3. Chart showing stratigraphy of Tertiary sedimentary rocks in Cook Inlet Basin and Susitna Lowlands areas........... 5 

4. Photograph showing rocks of the Kenai Group on Fairview Mountain ..................................................................... 6 

5. Scatterplots of uranium versus thorium, copper, and vanadium for samples of the Kenai Group.............................. 10 

6. Photograph showing rocks of the Sterling(?) Formation at Camp Creek ................................................................... 12 

TABLES 

1. X-ray diffractogram peaks (Cu, K-alpha radiation) measured for the rock samples in the study............................... A6 

2. Correlation coefficient matrix for data set ...... ....... .......... .. ... .. ............... .. ..... .. ... .. .. ... ....... .. ... ..... ......... ....... ................. 8 

3. Varimax factor analysis for five factors...................................................................................................................... 9 

4. Clay contents of selected samples............................................................................................................................... 11 
Geology, Geochemistry, and Uranium Favorability of the 

Tertiary Kenai Group in the Susitna Lowlands at the 

Northern End of Cook Inlet Basin, Alaska 

By Kendell A. Dickinson 

ABSTRACT 

The Susitna Lowlands at the northern end of the Cook 

Inlet Basin in south-central Alaska are underlain by more 

than 940 m of continental clastic rocks that are approximately correlative with the Tertiary Kenai Group farther to 

the south in the basin. The Susitna Lowlands section, which 

consists mostly of nonmarine conglomerate, sandstone, and 

shale and smaller amounts of bedded coal, is divided into the 

Tyonek(?) and Sterling(?) Formations. Parts of this section 

were measured and sampled during reconnaissance studies 

in 1977 and 1978 to determine favorability for uranium 

deposits. Samples were analyzed for uranium, thorium, and 

19 other elements, and minerals were identified by X-ray diffraction. Statistical studies of the chemical and mineralogical data suggest that uranium is associated with copper, 

titanium, scandium, and aluminum, that chlorite and illite are 

detrital clay minerals, and that smectite and kaolinite are 

diagenetic. 

Although the Kenai Group in the Susitna Lowlands 

exhibits most if not all of the favorable characteristics for 

epigenetic sedimentary uranium deposits, no significant 

large deposits are known. Uranium is epigenetically 

enriched (72 ppm eU30 8) in a kaolinitic mudstone layer 

associated with a thin coal bed in the Sterling(?) Formation 

at Camp Creek. The Sterling(?) is more highly oxidized t11an 

the underlying Tyonek(?) Fonnation and probably as a 

whole contains more epigenetic uranium. The positive correlation between uranium and copper suggests that copper may 

also have been epigenetically enriched. 

A correlation coefficient matrix and an R-mode factor 

analysis using a five-factor model were determinined for the 

chemical and mineralogical data base of 29 samples. The 

factors are interpreted to represent fine-grained clayey sediments, rare earth elements, feldspathic coarse-grained sediments, iron-manganese, and altered fine-grained sediments. 

INTRODUCTION 

The Susitna Lowlands area (fig. 1) is a northern extension of the Cook Inlet Basin in south-central Alaska (Wahrhaftig, 1965). It contains a sequence of Tertiary continental 

sedimentary rocks of the Kenai Group that includes the 

Miocene Tyonek(?) and the Pliocene Sterling(?) Formations 

(Reed and Nelson, 1980). These rocks approximately correlate with the Kenai Group in the main part of the Cook Inlet 

Basin to the south where the Kenai Group, in ascending 

order, consists of the Oligocene Hemlock Conglomerate, the 

Oligocene and Miocene Tyonek Formation, the Miocene 

Beluga Formation, and the Miocene and Pliocene Sterling 

Formation (Magoon and others, 1976). 

Early interest in Tertiary sedimentary rocks of Cook 

Inlet was motivated by the demand for coal. Coal resources 

of the northwestern part of the Cook Inlet area were 

described by Barnes (1966). Oil was discovered in 1957 

(Parkinson, 1962), and much of the later interest in the area 

was stimulated by the search for petroleum (Calderwood and 

Fackler, 1966, 1972; Crick, 1971; Kirschner and Lyon, 

1973). During the late 1970's interest developed in the uranium potential of the Kenai Group because the unit contains 

the necessary elements of a uranium resource area. Croff and 

others ( 1977) considered the area of this report favorable for 

sandstone-hosted uranium deposits. The area contains potentially favorable uranium sources in the fonn of felsic igneous 

rocks within and near the study area and in the Alaska and 

Aleutian Ranges to t11e northwest. In addition, the potential 

host rocks contain igneous constituents that could have supplied uranium to the circulating ground water. Thick Tertiary 

sequences of porous sandstone and conglomerate form 

favorable uranium host rocks. These possible host rocks contain abundant organic material that could have produced the 

chemically reducing environment necessary for deposition 

of the uranium (Dickinson and Campbell, 1978). 

Al 
A2 URANIUM FAVORABILTIY OF TERTIARY ROCKS, SOU1H-CENTRAL ALASKA 

70'-

Shirley Lakep 

160' 

I 

ALASKA 

500 

'\40' 

\ -lG' 

\ 

\ 

\ 

\ 

\ 

1000 KILOMETERS 

59'.__ _____ ___;_:__ ______________________ ___.. 

100 200 KILOMETERS 

Figure 1. Index map of south-central Alaska showing study area (dark-shaded area) and areas of Tertiary continental 

sedimentary rocks (unit Tc, light-shaded areas). Geology from Biekman (1980). 
KENAI GROUP, SUSI1NA LOWLANDS, NORTHERN END OF COOK INLET BASIN A3 

The study area includes an area of scattered outcrops on 

the west side of the Susitna River valley north of the Castle 

Mountain fault (fig. 1, 2). The study area extends from 

Hewitt Lake on the south to the vicinity of Kahiltna Lake on 

the north. It includes outcrops west of the Yentna River, at 

Fairview Mountain, and in the Peters Hills and Cache Creek 

areas. These outcrops were selected because of their accessibility from a base camp at Talkeetna, Alaska, during the 

period available for fieldwork. Samples of the Tertiary sedimentary rocks as described herein were collected during a 

reconnaissance survey by helicopter August 16-23, 1977 

and on a one-day return trip to one of the sites on July 30, 

1978. 

Eighteen sections were measured, and 29 samples were 

collected (fig. 2). The present report is based on chemical 

and mineralogical analyses of the samples (appendix 1) and 

on the described sections (appendix 2). These data provide 

new insight into diagenesis and sedimentation of the Tertiary 

units, as well as their favorability for uranium deposits. 

Acknowledgments.-Gary Skipp prepared the oriented 

clay mineral mounts for X-ray diffraction studies and operated the X-ray diffraction machine. Samples were chemically analyzed in laboratories of the U.S. Geological Survey 

atLakewood, Colorado. D.M. McKown supervised the radiochemical analysis, J.E. Taggart supervised the X-ray spectroscopy analysis, and D.E. Detra and L.R. Layman 

supervised the optical spectroscopy analysis. 

GEOLOGY 

The Cook Inlet Basin in the coastal area of south-central Alaska is mostly to the southeast of the present study 

area (Wahrhaftig, 1985). The basin separates the Aleutian 

and Alaska Ranges on the northwest from the Kenai and 

Chugach Ranges on the southeast (fig. 1). The Talkeetna 

Mountains and the Copper River Basin are to the northeast 

of Cook Inlet Basin. The Cook Inlet Basin is about 100 by 

300 km; its axis is oriented about N. 25° E. It contains a 

sequence of nonmarine Tertiary sedimentary rocks as thick 

as 8,500 m comprising the Oligocene to Pliocene Kenai 

Group and the underlying Paleocene and Eocene West Foreland Formation (fig. 3). These Tertiary rocks overlie Jurassic 

and Cretaceous rocks (Kremer and Stadnicky, 1985) and 

underlie Quaternary alluvium and glacial deposits. 

The Cook Inlet Basin is generally bounded on the east 

by the Border Ranges fault (Knik fault of Magoon and others, 1976), which strikes about N. 30° E. (fig. 1). The Bruin 

Bay fault, which generally forms the western margin of the 

basin, extends northward about N. 45° E. and intersects the 

Castle Mountain fault in the northern part of the basin. The 

Castle Mountain fault trends about N. 60° E. and generally 

forms the northwestern boundary of the basin (fig. 1). Undivided equivalents of the Kenai Group and the West Foreland 

Formation extend north of the Castle Mountain fault into the 

Susitna Lowlands. Other minor faults and lineaments have 

been mapped on the Kenai Peninsula. Several gentle anticlines and synclines, whose axes parallel the long axis of the 

basin, were mapped by Magoon and others (1976) in the 

eastern half of the Cook Inlet Basin (fig. 1). Water of Cook 

Inlet covers most of the northwest half of the basin. 

The study area, to the north of the Cook Inlet Basin, 

contains scattered outcrops of the Miocene Tyonek(?) and 

Pliocene Sterling(?) Formations. Much of the study area is 

covered by Quaternary sedimentary deposits and glacial ice. 

The Tyonek(?) is unconformably underlain by thick 

sequences of Jurassic and Cretaceous metamorphic and sedimentary rocks including lithic graywacke, phyllite, and 

shale and locally interbedded lenses of quartz and chert conglomerate. This sequence contains thin beds of fossiliferous 

limestone and radiolarian chert with Jurassic and Cretaceous 

fossils in some areas and a few beds of red ferruginous sandstone in other areas. The rocks have been altered by thermal 

metamorphism near plutons and by low-grade metamorphism in other areas (Reed and Nelson, 1980). 

Parts of two early Tertiary plutons are present in the 

study area: the southeastern part of the Kahiltna pluton and 

the southern part of the Ruth pluton (fig. 2). The Kahiltna 

pluton consists of fine- to coarse-grained biotite and biotitemuscovite granite and granodiorite. The southern part of the 

Ruth pluton consists of coarse-grained biotite granite and 

granodiorite that is locally weathered to grus and contains 

rare muscovite and hornblende. Two small granitic intrusive 

bodies also are present in the study area (fig. 2) (Reed and 

Nelson, 1977). 

TERTIARY SEDIMENTARY ROCKS 

The Tertiary sedimentary rocks of the Cook Inlet Basin 

were frrst referred to as the Kenai Group by Dall and Harris 

(1892), who assigned the group to the Miocene. Barnes and 

Cobb (1959) and Parkinson (1962) referred to the same 

rocks as the Kenai Formation. The Kenai Group was later 

divided into five formations (Calderwood and Fackler 1966, 

1972; Crick, 1971; Magoon and others, 1976), in ascending 

order, the West Foreland Formation, Hemlock Conglomerate, Tyonek Formation, Beluga Formation, and Sterling Formation. Subsequently, Magoon and others (1976) removed 

the West Foreland Formation from the Kenai Group (fig. 3). 

In the Susitna Lowlands area, north of the Castle Mountain fault (fig. 1), the Kenai Group, which has a minimum 

thickness of 940 m, was divided into a lower, Miocene unit 

designated the Tyonek(?) Formation and an upper, Pliocene 

unit designated the Sterling(?) Formation (fig. 4) (Reed and 

Nelson, 1980). The Tyonek Formation was also mapped 

along the southern margin of the study area by Magoon and 

others ( 197 6). The West Foreland Formation, Hemlock Conglomerate, and Beluga Formation have not been recognized 

in the study area. The Alaska Range to the northwest and the 
A4 URANIUM FAVORABILITY OF TERTIARY ROCKS, SOUTII-CENTRAL ALASKA 

150.30' 

Figure 2 (above and facing column). Geology of the Susitna Lowlands area, Cook Inlet Basin, south-central Alaska. Locations of measured sections are also shown. Map area is shown in figure 1. Geology modified from Reed and Nelson (1977, 1980). 

Talkeetna Mountains to the northeast were important sediment sources for the Kenai Group in the Susitna Lowlands. 

The Tyonek(?) Formation, which has a minimum thickness of 170 m, is divided into sandstone and conglomerate 

members (fig. 2). The sandstone member conformably overlies or is interbedded with the conglomerate member. The 

conglomerate member of the Tyonek(?) consists of 40 percent or more conglomerate, 20 percent sandstone, and less 

than 40 percent siltstone, claystone, and coal (Reed and Nelson 1977). The conglomerate, which is poorly indurated and 

forms massive beds, is light brown, light gray, or bluish gray. 

Clasts are well rounded and their maximum size is about 10 
KENAI GROUP, SUSITNA LOWLANDS, NORTHERN END OF COOK INLET BASIN A5 

EXPLANATION 

Glacier 

Glacial, alluvial, and mass-wasting deposits, undivided 

(Quaternary) 

Sterling(?) Formation (Pliocene)-Orange, light-tan or lightgray, massive-bedded conglomerate; poorly to moderately well 

indurated with clayey and locally ferruginous matrix; coal 

fragments and locally discontinuous coal beds a few 

centimeters thick 

Tyonek(?) Formation, sandstone member (Miocene)-

Approximately 80 percent sandstone, 20 percent siltstone 

and claystone, and less than 1 percent coal, conglomerate, 

and volcanic ash. Sandstone is light gray to light brown, 

poorly sorted, and crossbedded. Coal is mostly in beds as 

thick as 2m 

Tyonek(?) Formation, conglomerate member (Miocene)-

Approximately 40 percent conglomerate, 20 percent 

sandstone, and less than 40 percent siltstone, claystone, and 

coal. Conglomerate is light brown, light gray, or bluish gray 

and poorly indurated; sandstone is light gray or brown, 

coarse, pebbly, and poorly sorted; siltstone, claystone, and 

coal form sets of fining-upward strata. Coal is in beds as thick 

as 17m 

Muscovite and biotite granite and granodiorite of Kahiltna 

pluton (early Tertiary) 

Biotite granite and granodiorite of Ruth pluton (early 

Tertiary) 

Intrusive rocks, undivided (early Tertiary and (or) Late 

Cretaceous)-Medium-grained biotite granite and other rocks 

~ Marine sedimentary rocks, undivided (Jurassic and Early 

Cretaceous) 

---- Contact-Dashed where approximate or inferred 

----;~-- Fault-Dashed where approximate or inferred, dotted where 

concealed. U (up) and D (down) indicate relative movement 

Location of measured section-Measured sections are shown 

in appendix 2 

em. Sandstone, siltstone, claystone, and coal comprise interbedded fining-upward sequences. The sandstone is arkosic, 

coarse grained, poorly indurated, and conglomeratic. In this 

report only sections 13 and 14 (appendix 2) are from the conglomeratic member of the Tyonek(?). Both of these sections 

consist of a mudstone-coal interval with conglomerate above 

and below. The coal-mudstone intervals probably correlate 

between these two sections, which are less than a kilometer 

apart (fig. 2). 

The sandstone member of the Tyonek(?) consists of 

approximately 80 percent sandstone, 20 percent siltstone, 

and less than 1 percent conglomerate, coal, and volcanic ash 

(Reed and Nelson, 1977). The sandstone is tan or light gray, 

coarse to medium grained, and poorly indurated and contains 

75-85 percent chert and quartz grains, 10-20 percent feldspar, and about 5 percent mafic grains including biotite, 

hornblende, clinozoisite, and chlorite. Sandstone beds are as 

thick as 60 m. The siltstone is light to medium gray and is in 

sequences as thick as 15m. Coal beds are as thick as 3m and 

Age 

Quaternary 

Pliocene 

Q. 

Miocene :I 

0 

t5 

"Cii 

c 

Q) 

::..::: 

Oligocene 

Eocene 

Paleocene 

Cook Inlet 

(Magoon and others, 1976) 

Alluvium and 

glacial deposits 

Sterling 

Formation 

Beluga 

Formation 

Tyonek 

Formation 

Hemlock 

Conglomerate 

West Foreland 

Formation 

Arkose Ridge Formation 

Q. 

:I 

e 

(.9 

"Cii 

c 

Q) 

::..::: 

Mesozoic and older rocks 

Susitna Lowlands 

(Reed and Nelson, 1977) 

Alluvium and 

glacial deposits 

Sterling(?) Formation 

Figure 3. Stratigraphy of Tertiary sedimentary rocks in Cook 

Inlet Basin and Susitna Lowlands areas, south-central Alaska. 

contain partly devitrified volcanic ash in beds as thick as 30 

em. The ash beds have been partly altered to clay minerals, 

probably kaolinite or smectite. 

Eight of the sections shown in appendix 2 (sections 2, 

5-8, 10-12) are from the sandstone member of the 

Tyonek(?) Formation. These sections show about 28 percent 

conglomerate, 39 percent sandstone, and 30 percent claystone, as well as about 3 percent coal. The conglomerate is 

light gray or brown, has a coarse-grained sandstone matrix, 

and is massive. The sandstone is light gray or brown, generally coarse grained, crossbedded, conglomeratic, and arkosic. TI1e mudstone is medium brown to dark gray and 

interbedded with coal. 

The Sterling(?) Formation, which is as thick as 770 m 

on Fairview Mountain and may be thicker in the lowlands, 

unconformably overlies the Tyonek(?) Formation (Reed and 

Nelson, 1977). It is lithologically similar to the Tyonek(?) in 

most respects and, according to Reed and Nelson (1977), 

may be partly derived from it. Conglomerate clasts in the 

Sterling(?) are lithologically similar to those in the 

Tyonek(?), but they are present in different proportions and 

have a larger maximum grain size (as much as 30 em in 

diameter). Conglomeratic sequences in the Sterling(?) are 

streaked with iron oxide at intervals, suggesting that the unit 

was more thoroughly oxidized than the more drab 

Tyonek(?). The Sterling(?) contains less carbonaceous material, which would have been a barrier to oxidation, than the 

underlying Tyonek(?). Little bedded coal is present in the 

Sterling(?) Fmmation in the Susitna Lowlands. 

Eight sections of the Sterling(?) Formation were 

described for this study (appendix 2, sections 1, 3, 4, 9, 

15-18). They consist of 62 percent conglomerate, 13 percent 

sandstone, and 25 percent claystone and mudstone. Coal in 

the Sterling(?) is present only as thin (10 em or less) 
A6 URANIUM FAVORABILITY OF TERTIARY ROCKS, SOUTII-CENTRAL ALASKA 

Figure 4. Several hundred meters of rocks of the Tertiary Kenai Group r on Fairview Mountain, 

Susitna Lowlands, south-central Alaska. Rock units: Ts, Sterling(?) Formation; Tts, sandstone member of Tyonek (?) Formation. 

discontinuous beds or as clasts. One thin coal bed at Camp 

Creek (section 15) is overlain by a bed of kaolinitic mudstone about 30 em thick. One of the samples from this bed 

(sample 28, appendix 1) contained 72 ppm uranium. 

METHODS 

The samples were analyzed for 21 elements and 6 minerals. Sample localities are shown in figure 2 and in measured sections in appendix 2. A data set was prepared 

containing 29 samples. 

Uranium and thorium contents were determined using 

the delayed-neutron method (Millard, 1976). Elemental values were determined using the six-step semiquantitative 

spectroscopy method (Myers and others, 1961). Mineralogical determinations were made by~ -Jay diffraction of wholerock cell mounts. For a few samples, oriented mounts of the 

<2-micron clay fractions were X-rayed after air-drying, glycolation, and heating to 550°C. The whole-rock X-ray diffraction data were obtained under conditions as uniform as 

possible for all of the runs. The same preparation procedures, 

instrument, and instrument settings were used for all samples. All the runs were made continuously, and a standard 

sample was X-rayed before and after each daily run. All 

analyses were made using sample splits. 

The relative abundances of quartz, feldspar, chlorite, 

illite, smectite, and amphibole were determined by measuring the areas of the X-ray diffraction peaks (in square inches) 

Table 1. X-ray diffractogram peaks (Cu, Ka radiation) 

measured for the rock samples in the study. 

Mineral X-ray diffraction Crystallographic 

peak (degrees 28) index 

Feldspar 26.9-27.9 002 

Quartz 20.8 100 

Illite 8.8 001 

Smectite 10.2 002 

Chlorite 12.5 002 

Kaolinite 12.5 001 

as recorded on the whole-rock diffractograms. Illite, as 

determined, includes the clay mineral illite and mica undifferentiated. The peaks measured for each mineral are listed 

in table 1. The areas of individual X-ray diffraction peaks 

provide estimates of the relative abundances of the minerals. 

The X-ray diffraction data do not, however, represent the 

absolute abundances of the minerals. 

A factor analysis and matrix of correlation coefficients 

for the data set in appendix 1 were calculated using a commercial program (Hintze, 1992). These analyses suggest 

many relationships that otherwise might be missed when 

perusing the data. The number of samples analyzed is too 

low, however, to represent comprehensively the total thickness of the combined Tyonek(?) and Sterling(?) Formations. 

The statistical analyses only represent the distribution and 

relationships of elements and minerals in the sample set. 
KENAI GROUP, SUSITNA LOWLANDS, NORTHERN END OF COOK INLET BASIN A7 

For the few qualified values in appendix 1, the following substitutions were made. For values listed as N (not 

detected), half of the lower detection limit was used; for values listed as L (detected, but not determined), three-fourths 

of the lower detection limit was used; for values prefixed by 

<, three-fourths of the less than value was used; for values 

listed as G (greater than 10 percent), 12.5 percent was used. 

Beryllium, boron, and lead were excluded from the statistical 

calculations because of the large number of qualified values 

for these elements. Kaolinite and smectite were not included 

because most of the samples contained none. Sample number 

28 was excluded because it was enriched in uranium. 

STATISTICAL ANALYSIS 

Mineralogical and chemical data for the Kenai Group in 

the Susitna Lowlands are given in appendix 1. Arithmetic 

means and standard deviations are given for the minerals and 

elements for each of the two stratigraphic units. A correlation 

coefficient matrix (table 2) and a five-factor model of an Rmode factor analysis (table 3) (Harmon, 1960) are presented 

for the data in appendix 1. The degree of correlation for all 

pairs of variables is shown by the correlation coefficients. 

The purpose of the factor analysis is to group related variables to reduce the amount of variation that must be interpreted and to investigate the underlying causes. The factors 

are calculated from the correlation matrix. The factor analysis includes the varimax rotation, which is rotation of the factors around the orthogonal axes. V arimax rotation enhances 

differences in factor loadings (Hintze, 1992). Factor loadings 

are the correlations between each variable and the factors. 

The sum of the squares of the factor loadings for each variable is equal to the communality, the proportion of each variable explained by the analysis. For more complete 

descriptions of factor analysis and its geological application 

see Davis (1986) and Koch and Link, (1971). 

A five-factor model was chosen because it is the simplest model that offers a reasonable explanation of the 

observed data and because it gives high communalities for 

the variables of primary interest, which include uranium and 

thorium. 

The geologic processes that underlie statistical factors 

are interpreted to be source area, sorting and alteration during 

transport and deposition, and postdepositional alteration 

(diagenesis). Differences in mineralogical and chemical 

makeup of the source areas result in differences in the composition of the sediment produced. During transport, the sediment is sorted into finer clay and coarser sand. The sand and 

clay fractions have somewhat different mineralogical and 

chemical makeup. Chemical and mineralogical alteration 

may also occur during sediment transport. Diagenesis results 

in changes in mineralogical and chemical makeup after lithification. The calculated factors represent combinations of 

the above processes that in some cases make interpretation 

speculative. 

Factor one.-Factor one consists of potassium, chlorite, 

chromium, illite, magnesium, and zirconium (table 3). In 

part, this factor represents the claystone and mudstone containing the fine-grained clay minerals chlorite and illite. 

There is a strong correlation between chlorite and illite in the 

rocks of the Kenai Group, not only in this area, but also in 

the Tyonek -Capps Glacier area (Dickinson and others, this 

volume) and on the Kenai Peninsula (Dickinson and Skipp, 

1992). Magnesium and potassium are expected in this factor 

because magnesium is a constituent of chlorite and potassium is a constituent of illite. The occurrence of chromiuim 

and zirconium in this factor is less easy to explain. Magnesium and chromium both suggest a relation to a mafic source 

area. 

Factor two.-Factor two consists of Cu, Sc, Ga, V, Ba, 

AI, Ni, U, and Ti (table 3). The relationships between these 

elements are complex and not entirely clear. The factor contains uranium, which is epigenetically enriched in three of 

the samples (fig. 5A) and otherwise is related to thorium 

(r=+0.36) and other elements. The relation between uranium 

and copper (r=+0.8, table 2, fig. 5B) suggests that some parallel enrichment of the copper in the epigenetic environment 

may also have occurred, as discussed later. Vanadium is 

related to uranium (r=+0.53, table 2, fig 5C). Vanadium is 

typically related to carbonaceous material in sedimentary 

rock, and the relation between uranium and carbonaceous 

material in enriched samples may explain this correlation. 

Uranium ore on the Colorado Plateau also typically contains 

large amounts of vanadium (Fischer, 1968). Nickel and copper together with chromium, which has a high secondary 

loading in this factor, are linked by their common occurrence 

in sulfide minerals. Factor two also includes gallium and aluminum, which are commonly present together in finegrained sediments and sedimentary rocks (hydrolysates) 

because of similar ionic potential (Mason, 1966, 

p. 163-164). Scandium, which is also in this factor, is generally present in greater amounts in fine-grained sedimentary 

rocks than in sandstone. Titanium, which is in this factor 

despite the low value of its loading (-0.59, table 3), is commonly enriched in placer deposits, and its occurrence here is 

not explained. In general, this factor is interpreted to represent altered fine-grained sedimentary rocks. 

Factor three.-Factor three consists of plagioclase, 

sodium, strontium, and calcium (table 3). Plagioclase is 

present mainly as detrital grains in sandstone and coarser 

clastic rocks. Strontium, calcium, and sodium are all present 

in plagioclase. Strontium substitutes for calcium in plagioclase because of similar ionic charge and radius. A correlation between strontium and calcium is expected in granitic 

but not in basaltic rocks. 

Factor four.-Factor four consists only of iron and 

manganese (table 3). These two elements behave similarly in 

oxidation-reduction environments and frequently are present 

together in oxide or hydroxide minerals. They are present 

together in the Sterling and Beluga Formations on the Kenai 
A8 URANIUM FAVORABILITY OF TERTIARY ROCKS, SOU1H-CENTRAL ALASKA 

Table 2. Correlation coefficient matrix for data set. 

[Data set is given in appendix 1] 

Uranium Thorium Iron Magnesium Calcium Titanium 

Uranium 1.00 

Thorium 0.36 1.00 

Iron -0.31 -0.22 1.00 

Magnesium -0.16 0.32 -0.01 1.00 

Calcium 0.27 0.40 0.08 -0.03 1.00 

Titanium 0.58 0.51 -0.23 0.45 0.34 1.00 

Manganese -0.34 -0.19 0.80 -0.10 0.16 -0.39 

Barium 0.24 0.16 0.02 0.47 -0.26 0.54 

Chromium 0.06 0.43 0.08 0.68 -0.25 0.44 

Copper 0.80 0.32 -0.12 0.04 0.04 0.60 

Nickel 0.19 0.18 0.20 0.32 -0.26 0.38 

Scandium 0.50 0.40 -0.07 0.57 -0.15 0.63 

Strontium 0.33 0.33 -0.39 0.35 0.46 0.65 

Vanadium 0.53 0.37 -0.24 0.49 -0.10 0.60 

Yttrium 0.56 0.61 -0.35 0.19 0.26 0.31 

Zirconium 0.07 0.15 -0.10 0.52 0.05 0.31 

Aluminum 0.44 0.49 -0.28 0.45 -0.18 0.50 

Sodium -0.10 -0.05 0.10 0.18 0.21 0.16 

Potassium -0.10 0.38 0.02 0.66 -0.40 0.25 

Gallium 0.43 0.31 -0.14 0.36 -0.22 0.50 

Ytterbium 0.40 0.69 -0.26 0.45 0.11 0.52 

Quartz -0.54 -0.43 -0.22 -0.01 -0.27 -0.29 

Plagioclase 0 0.09 -0.10 0.31 0.41 0.35 

Chlorite -0.22 0.34 -0.13 0.47 -0.36 0.06 

Illite -0.26 0.10 0.06 0.45 -0.37 0 

Manganese Barium Chromium Copper Nickel Scandium 

Manganese 1.00 

Barium -0.19 1.00 

Chromium -0.09 0.70 1.00 

Copper -0.17 0.49 0.29 1.00 

Nickel 0.01 0.69 0.73 0.35 1.00 

Scandium -0.25 0.73 0.79 0.69 0.62 1.00 

Strontium -0.26 0.12 0.07 0.39 -0.08 0.30 

Vanadium -0.35 0.66 0.62 0.68 0.51 0.87 

Yttrium -0.23 -0.07 0.20 0.38 0.14 0.39 

Zirconium -0.34 0.41 0.44 0.07 0.27 0.43 

Aluminum -0.31 0.57 0.64 0.59 0.51 0.71 

Sodium 0.11 0.33 0.14 0.07 0.13 0.16 

Potassium -0.17 0.63 0.81 0.17 0.48 0.64 

Gallium -0.20 0.70 0.62 0.67 0.44 0.70 

Ytterbium -0.41 0..41 0.64 0.36 0.47 0.68 

Quartz -0.36 -0.09 -0.19 -0.56 -0.19 -0.40 

Plagioclase -0.05 0.17 -0.01 0.04 -0.04 0.11 

Chlorite -0.30 0.21 0.57 -0.08 0.11 0.29 

Illite -0.06 0.35 0.53 -0.01 0.26 0.35 

Peninsula (Dickinson and Skipp, 1992) but .not in rocks of 

the Kenai Group in the Tyonek -Capps Glacier area (Dickinson and others, this volume). Manganese is leached before 

iron in soils and follows iron in precipitation in sediments. 

Factor jive.-Quartz is at the positive pole in factor 

five, and ytterbium, thorium, and yttrium are at the negative 

pole (table 3). The distribution of quartz is complex because 

it is present as grains of all sizes, including clay sizes, and 

possibly also as an alteration product, although none was 

identified. Ytterbium and yttrium are rare earth elements 

and, as such, can be expected to be present together because 

of similar geochemical characteristics. 
KENAI GROUP, SUSI1NA LOWLANDS, NORTHERN END OF COOK INLET BASIN A9 

Table 2. Correlation coefficient matrix for data set-Continued. 

Strontium Vanadium Yttrium Zirconium Aluminum Sodium 

Strontium 1.00 

Vanadium 0.36 1.00 

Yttrium 0.22 0.36 1.00 

Zirconium 0.25 0.37 0.11 1.00 

Aluminum 0.24 0.70 0.43 0.23 1.00 

Sodium 0.39 0.08 -0.15 0.41 0.12 1.00 

Potassium 0.01 0.51 0.11 0.52 0.55 0.26 

Gallium 0.29 0.68 0.25 0.18 0.80 0.14 

Ytterbium 0.27 0.60 0.64 0.51 0.54 0.13 

Quartz -0.19 -0.34 -0.55 0.27 -0.34 0 

Plagioclase 0.50 0.18 -0.08 0.29 0.10 0.59 

Chlorite -0.02 0.20 0.14 0.32 0.25 -0.06 

Illite -0.21 0.25 0.07 0.26 0.27 0.23 

Potassium Gallium Ytterbium Quartz Plagioclase Chlorite 

Potassium 1.00 

Gallium 0.51 1.00 

Ytterbium 0.62 0.37 1.00 

Quartz -0.06 -0.45 -0.25 1.00 

Plagioclase 0.10 0.01 0.06 -0.07 1.00 

Chlorite 0.78 0.29 0.48 0.11 -0.20 1.00 

Illite 0.69 0.31 0.31 -0.02 0.19 0.55 

Table 3. Varimax factor analysis for five factors. 

[Primary factor loadings are are underlined] 

Factor 1 Factor 2 Factor 3 Factor4 Factor 5 Communality 

Uranium -0.42 -0.64 -0.01 -0.25 -0.47 0.87 

Thorium 0.28 -0.18 -0.10 -0.09 -0.81 0.79 

Iron 0.06 0.06 0.02 0.90 0.16 0.84 

Magnesium 0.71 -0.21 -0.37 -0.02 -0.14 0.70 

Calcium -0.36 0.23 -0.59 0.14 -0.57 0.87 

Titanium 0.04 -0.59 -0.47 -0.24 -0.35 0.75 

Manganese -0.12 0.17 0.01 0.94 0.04 0.92 

Barium 0.39 -0.78 -0.21 0 0.24 0.86 

Chromium 0.74 -0.56 -0.02 0.10 -0.12 0.89 

Copper 0.21 -0.85 -0.06 -0.05 -0.27 0.85 

Nickel 0.36 -0.66 0.04 0.22 0.06 0.62 

Scandium 0.40 -0.82 -0.12 -0.06 -0.22 0.89 

Strontium -0.13 -0.21 -0.69 -0.31 -0.32 0.74 

Vanadium 0.25 -0.79 -0.15 -0.20 -0.20 0.79 

Yttrium 0.06 -0.21 0.12 -0.17 -0.84 0.79 

Zirconium 0.52 -0.15 -0.46 -0.28 0.04 0.59 

Aluminum 0.31 -0.73 -0.01 -0.17 -0.25 0.72 

Sodium 0.17 -0.10 -0.74 0.16 0.20 0.66 

Potassium 0.89 -0.36 -0.04 0 -0.03 0.92 

Gallium 0.23 -0.81 0 -0.05 -0.10 0.73 

Ytterbium 0.52 -0.37 -0.11 -0.24 -0.57 0.80 

Quartz 0.18 0.45 -0.03 -0.48 0.62 0.85 

Plag. 0.03 -0.01 -0.85 0 0.01 0.73 

Chlorite 0.82 0.03 0.22 -0.22 -0.15 0.79 

Illite 0.74 -0.12 0.01 0.10 0.08 0.58 
AlO URANIUM FAVORABILITY OF TERTIARY ROCKS, SOUTII-CENTRAL ALASKA 

14 I I I I I 

.... 12 - - z /---...... 0 

::J oo I ...J ' 10 - I " - ~ D .... \ 

a: oD \ \ 

LLJ \ \ a.. 8- D .... \ \ - (/) \ 1- \ 

a: .... D \ I <( " .... a.. 6~ .... ~ 

Enriched in uranium/'--...--

I 

~ .... - 9::J .... 2:- .... .... ::l 

a: 4 o ...._ -

0 D 

J: 

1-

2- .... -

0 I I I I I 

2 4 6 8 10 12 14 

A 

250 I I I T I 

z 200 - - 0 

::J 

...J 

~ 

a: 150 - LLJ - a.. 

(/) 

1-

a: 

<( 

a.. 

~ 100 - .... - a:' 

LLJ 

a.. .M:I:II:DD Cil 

a.. 

0 50 ~· .... u -

DIJ .... .... B=l D 

0 I I I I I 

2 4 6 8 10 12 14 

B 

250 

z 200 D .... 0 

::J 

...J 

~ 

a: 

LLJ 150 ~ ..A.D a.. 

(/) 

1-

a: 

<( 

a.. 

~ 100 .... .... 2:-

::l 

i5 IDl D 

<( Figure 5. Scatterplots of uranium versus (A) z 50 <( thorium, (B) copper, and (C) vanadium for > D samples of the Tertiary Kenai Group. Sample 

data are given in appendix 1. Open squares in0 dicate Tyonek (?) Formation; solid triangles in2 4 6 8 10 12 14 

c URANIUM, IN PARTS PER MILLION 

dicate Sterling (?) Formation. Sample number 

28, which is a uranium outlier, is not included. 
KENAI GROUP, SUSITNA LOWLANDS, NOR1HERN END OF COOK INLET BASIN All 

CLAY MINERALS 

Of the clay minerals present in rocks of the Kenai 

Group (table 4), chlorite and illite are interpreted as detrital, 

and kaolinite and smectite are thought to be mostly diagenetic. Chlorite and illite are abundant in samples that show 

no evidence of diagenesis. In addition, chlorite and illite are 

closely associated in samples of the Kenai Group from the 

Susitna Lowlands (r=+0.77), from the Capps Glacier area 

(r=+0.67) (Dickinson and others, this volume), and from the 

Kenai Peninsula area (r=+0.9) (Dickinson and Skipp, 1992). 

This association would be improbable if either the illite or 

the chlorite was of diagenetic origin. 

Most of the smectite probably formed from volcanic 

material originally contained in the sediments, but some of it 

may have been altered prior to sediment deposition and is, 

therefore, detrital (Dickinson and others, this volume). The 

kaolinite has not been extensively studied but apparently is 

associated with coal beds or other occurrences of abundant 

carbonaceous material. The kaolinite probably fonned 

diagenetically from volcanic material in the acidic conditions that developed in the peat-fonning environment. The 

vitreous volcanic component of these sediments is not 

detectable by X -ray diffraction, and the smectite or kaolinite, 

which is detectable by X -ray diffraction, may be a reasonable indicator of original volcanic material in the sediments. 

URANIUM FA VORABILITY 

In the data set for this study, three samples from the 

Sterling(?) Formation contained more than 10 ppm U 

(appendix 1). Uranium at these concentrations in sedimentary rocks probably results from epigenetic enrichment. This 

origin is especially likely for a kaolinitic mudstone sample 

from the Sterling (?) Formation in the Camp Creek area that 

contains 72 ppm U30 8 (sample 28, fig. 6, appendix 1). The 

sample was collected within a few centimeters above a thin 

coal bed that could have produced the reducing environment 

necessary to precipitate uranium from ground water. Epigenetic enrichment of copper, which, similar to uranium, is 

mobilized by oxidizing solutions and precipitated in reducing environments, may also have occurred. The copper values in the data set are not high, averaging 48 ppm for the 

Sterling(?) Formation and 65 ppm for the Tyonek(?) Fonnation (appendix 1), compared to an average of 30 ppm for 

igneous rocks of the upper continental crust (W edepohl, 

1971). There is, however, a fairly strong correlation between 

uranium and copper in the data set presented here (r=+0.8, 

table 2, fig. 5A). The correlation coefficient for uranium and 

copper is +0.48 for the data set from the Tyonek -Capps Glacier area (Dickinson and others, this volume) and +0.31 for 

the data set from Kenai Peninsula area (Dickinson and 

Skipp, 1992). 

Table 4. Clay content of selected samples. 

[Sample numbers refer to appendixes 1 and 2. X indicates present in 

detectable amount; leaders ( --) indicates not detected] 

Field 

number 

2 

4 

5 

10 

11 

Smectite Illite Chlorite 

TYONEK(?) FORMATION 

X X X 

X X 

X X 

X X X 

X X 

STERLING(?) FORMATION 

15 X X X 

Kaolinite 

X 

X 

28 X 

29 X 

Uranium is also positively correlated with Ti, Sc, V, Al, 

Y, Yb, and Ga (table 2). In the Capps Glacier area (fig. 1) 

uranium is associated with Th, Ga, K, Yb, Y, and V (Dickinson and others, this volume), and in the Kenai Peninsula area 

farther to the south the only strong elemental associations 

with uranium are thorium and chromium (Dickinson and 

Skipp, 1992). These associations are believed to be mostly 

detrital in nature in both areas. The strong association 

between uranium and thorium in the Tyonek-Capps Glacier 

and Kenai Peninsula areas indicates that uranium has not 

been mobilized in these rocks. The uranium-thorium association in the Susitna Lowlands is weaker (r=0.36, table 2). 

Figure 5A shows that the correlation between uranium and 

thorium holds true for most of the samples in the S usitna 

Lowlands but not for those with the higher uranium values. 

If the two outliers shown in figure 5 are omitted, the correlation is stronger (r=+0.6). The accuracy of thorium measurements by the delayed neutron method decreases in samples 

having high uranium contents, making the relationships difficult to quantify in samples enriched in uranium. 

Judging from its color, the Sterling(?) Formation is 

more oxidized than the underlying Tyonek(?) Formation. 

The Sterling(?) lacks carbonaceous material and contains 

very little bedded coal that would retard oxidation. The 

Tyonek(?), on the other hand, contains abundant bedded coal 

and other carbonaceous material that could act as a barrier to 

widespread oxidation. Uranium was apparently mobilized 

by oxidizing ground water in the Sterling(?) and deposited in 

locally reducing environments. In the Susitna Lowlands 

area, the Sterling(?) Formation therefore has a higher potential for epigenetically enriched uranium deposits than does 

the Tyonek(?). 

In addition to the uranium occurrences in the Sterling 

(?) Formation, other uranium occurrences are present in and 

near the study area. These include uraniferous resistate minerals in stream placers in the Cache Creek and upper Peters 

Creek areas, high uranium values in heavy-mineral samples 

from the Kahiltna and Ruth plutons (fig. 2), hydrothermal 
A12 URANIUM FAVORABILITY OF TERTIARY ROCKS, SOUlli-CENTRAL ALASKA 

Figure 6. Sterling(?) Formation at Camp Creek (section 15, appendix 2).A, Close-up view; sample 27 is gray clayey sandstone, sample 28 uraniferous kaolinitic mudstone, and sample 29 barren 

kaolinitic mudstone. Sample bags show collections locations. Hammer is shown for scale. B, General view showing approximate area of A (indicated by outline). 

vein deposits in the Tonzona pluton, and mineralization 

along fractures or joints near Shirley Lake (fig. 1). Robinson 

and others (1955) reported eU values as high as 0.009 percent equivalent U30 8 in concentrates from Quaternary 

stream gravels along Cache Creek and upper Peters Creek in 

the study area. Uranium and thorium were contained in 

grains of zircon, monazite, and uranothorianite that were 

found in the concentrates. Reed and others (1978) suggested 

that some of these minerals were derived from erosion of the 

Kenai Group. Curtin and others (1979) reported a uranium 

value of 2,200 ppm for a selected nonmagnetic heavy-mineral concentrate of a stream-sediment sample on the Kahiltna 

pluton. Other samples from the pluton contained much less 

uranium. A significant uranium occurrence is present at the 
KENAI GROUP, SUSITNA LOWLANDS, NORTIIERN END OF COOK INLET BASlN A13 

Mespelt prospect, which is associated with the Late Cretaceous or early Tertiary Tonzona pluton about 35 Ian northwest of the northern margin of the study area (fig. 1). This 

prospect is a hydrothermal vein deposit, and zeunerite and 

metazeunerite (copper-uranium arsenates) are present (Mal .. 

oney and Thomas, 1966). A minor supergene uranium occurrence is present in and around joints and fractures in a 

basaltic and andesitic tuff near Shirley Lake (Freeman, 

1963), about 25 km west of the southwest comer of the study 

area (fig. 1). 

Friedman and Hindennan (1978) described two uranium occurrences in the Talkeetna 2° quadrangle, one at 

Tonzona pluton and one in the Cache Creek area. Both 

occurrences are described preceding. Friedman and Hinderman listed only the Tonzona pluton as an area favorable for 

commercial-size uranium deposits in the Talkeetna quadrangle but did not evaluate the Tertiary sedimentary rocks considered herein for that area. 

REFERENCES CITED 

Barnes, F .F., 1966, Geology and coal resources of the Beluga-Y entna region, Alaska: U.S. Geological Survey Bulletin 1202-C, 

54p. 

Barnes, F.F., and Cobb, E.H., 1959, Geology and coal resources of 

the Homer district, Kenai coal field, Alaska: U.S. Geological 

Survey Bulletin 1058-F, p. 217-260. 

Beikman, H.M., 1980, Geologic map of Alaska: U.S. Geological 

Survey, scale 1:2,500,000. 

Calderwood, K.W., and Fackler, W.C., 1966, Significant oil and 

gas developments in Alaska, 1965-1966 [abs.]: American 

Association of Petroleum Geologists Bulletin, v. 50, no. 9, 

p. 2029-2030. 

---1972, Proposed stratigraphic nomenclature for Kenai 

Group, Cook Inlet Basin, Alaska: American Association of 

Petroleum Geologists Bulletin, v. 56, no. 4, p. 739-754. 

Crick, R.W., 1971, Potential petroleum reserves, Cook Inlet, Alaska: American Association of Petroleum Geologists Memoir 

15,v. 1,p. 109-119. 

Croff, C., Lessman, J., Bigelow, C., and Ruzicka, J., 1977, Uranium 

favorability of the Cook Inlet Basin, Alaska: Prepared by 

WGM Inc., Anchorage, Alaska, for the U.S. Department of 

Energy, Grand Junction Office, v. 19 163 p., v. 2, 138 p., v. 3, 

56 maps. . 

Curtin, G.C., O'Leary, R.M., Tripp, R.B., and Cooley, E.F., 1979, 

Geochemical and generalized geologic maps showing the distribution and abundance of thorium and the distribution of uranium in the central Alaska Range, Talkeetna quadrangle, 

Alaska: U.S. Geological Survey Open-File Report, scale 

1:250,000. 

Dall, W.H., and Harris, G.D., 1892, Correlation papers, Neogene: 

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Davis, J.C., 1986, Statistics and data analysis in geology (2nd ed.): 

New York, Wiley, 646 p. 

Dickinson, K.A., and Campbell, J.A., 1978, Epigenetic mineralization and areas favorable for uranium exploration in Tertiary 

continental sedimentary rock in south-central Alaska, a preliminary report: U.S. Geological Survey Open-File Report 

78-757, 14 p. 

Dickinson, K.A., and Skipp, G.L., 1992, Clay mineral depositional 

facies and uranium resource potential in part of the Tertiary 

Kenai Group, Kenai Peninsula, Alaska: U.S. Geological Survey Bulletin 1999, p. 81-99. 

Fischer, R.P., 1968, The uranium and vanadium deposits of the Colorado Plateau region, in Ore deposits of the United States. 

1933-1967 (Graton-Sales Volume): New York, American 

Institute of Mining, Metallurgical, and Petroleum Engineers, 

v. 1, p. 735-746. 

Freeman, V.L., 1963, Examination of uranium prospects, 

1956-Shirley Lake, in Contributions to economic geology of 

Alaska: U.S. Geological Survey Bulletin 1155, p. 29-30. 

Friedman, G.R., and Hinderman, T.K., 1982, National uranium 

resource evaluation, Talkeetna quadrangle, Alaska, U.S. 

Department of Energy Open-File Report PGJ/F--058(82), 27 p. 

Harmon, H.H., 1960, Modern factor analysis (2nd rev. ed.): Chicago, University of Chicago Press, 471 p. 

Hintze, J.L., 1992, Number cruncher statistical system, advanced 

statistics, version 5.3, reference manual: Kaysville, Utah, J.L. 

Hintze, 424 p. 

Kirschner, C.E., and Lyon, C.A., 1973, Stratigraphic and tectonic 

development of Cook Inlet petroleum province, in Pitcher, 

M.G., ed. Arctic geology: American Association of Petroleum 

Geologists Memoir 19, p. 396-407. 

Koch, G.S., Jr., and Link, R.F., 1971, Statistical analysis of geological data, volume 2: New York, Dover, 417 p. 

Kremer, M. C., and Stadnicky, George, 1985, Tertiary stratigraphy 

of the Kenai Peninsula-Cook Inlet region, in Sisson, Alexandra, ed., Guide to the geology of the Kenai Peninsula: Anchorage, Alaska Geological Society, p. 24-42. 

Magoon, L.B., Adkison, W.L., and Egbert, R.M., 1976, Map showing geology, wildcat wells, Tertiary plant fossil localities, K-Ar 

age dates, and petroleum operations, Cook Inlet area, Alaska: 

U.S. Geological Survey Miscellaneous Investigations Series 

I-1019, scale 1:250,000, 3 sheets. 

Maloney, R.P., and Thomas, B.l., 1966, Investigation of Purkeypile 

prospects, Kushkokwim River Basin, Alaska: U.S. Bureau of 

Mines Open-File Report, 12 p. 

Mason, Brian, 1966, Principles of geochemistry (3rd ed.): New 

York, Wiley, 329 p. 

Millard, D.J., Jr., 1976, Determinations of uranium and thorium in 

USGS standard rocks by the delayed neutron technique: U.S. 

GeologicaJ Survey Professional Paper 840, p. 61-65. 

Myers, A.T., Havens, R.G., and Dunton, P.J., 1961, A spetrochemical method for the analysis of rocks, minerals and ores: U.S. 

Geological Survey Bulletin 1084-I, p. 1207-1229. 

Parkinson, L.J., 1962, One field, one giant-The story of Swanson 

River: Oil and Gas Journal, v. 60, no. 13, p. 180-183. 

Reed, B.L., and Nelson, S.W., 1977, Geologic map, Talkeetna 

quadrangle: U.S. Geological Survey Miscellaneous Field Studies Map MF-870-A, scale 1 :250,000. 
A14 URANIUM FAVORABILITY OF TERTIARY ROCKS, SOUTII-CENTRAL ALASKA 

--1980, Geologic map of the Talkeetna quadrangle, Alaska: 

U.S. Geological Survey Miscellaneous Investigations 1-1174, 

scale 1:250,000. 

Reed, B.L., Nelson, S.W., Curtin, G.C., and Singer, D.A., 1978, 

Mineral resources map of the Talkeetna quadrangle, Alaska: 

U.S. Geological Survey Miscellaneous Field Studies Map 

MF-870-D, scale 1:250,000. 

Robinson, G.D., Wedow, Helmuth, Jr., and Lyons, B.B., 1955, 

Radioactivity in the Cache Creek area, Yentna District, Alaska, 

1945: U.S. Geological Survey Bulletin 1024-A, p. 1-23. 

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Geological Survey Professional Paper 482, 52 p. 

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Winston 231 p. 
KENAI GROUP, SUSITNA LOWLANDS, NORlliERN END OF COOK INLET BASIN A15 

APPENDIX I-CHEMICAL AND MINERALOGICAL DATA FOR SAMPLES OF THE 

TYONEK(?) AND STERLING(?) FORMATIONS OF THE TERTIARY KENAI GROUP 

Samples are shown by number in the measured sections of appendix 2. Elements are in parts per million (ppm) or percent, 

as indicated at top of column. Values for quartz, plagioclase, chlorite, illite, smectite, and amphibole are peak area in square 

inches; the crystallographic indices of the peaks measured are given in table 1. Mean is the arithmetic mean; St. Dev. is standard deviation. For values listed as N (not detected), half of the lower detection limit was used; for values listed as L (detected, 

but not determined), three-fourths of the lower detection limit was used; for values prefixed with <, three-fourths of the less 

than value was used; for values listed as G (greater than 10 percent), 12.5 percent was used. 

A. Description of samples 

Sample Measured 

number section 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

25 

26 

27 

28 

29 

7 

8 

6 

2 

13 

11 

10 

5 

5 

14 

14 

12 

12 

9 

17 

18 

3 

15 

16 

1 

4 

15 

15 

15 

15 

15 

15 

15 

15 

Rock type 

TYONEK(?) FORMATION 

Claystone, gray-brown, dense, micaceous 

Sandstone, gray-brown, dense, micaceous 

Claystone, light-brown, dense, micaceous 

Claystone, medium-gray to brown, dense 

Claystone, light-gray, sandy, micaceous, noncalcareous 

Siltstone, medium-gray, noncalcareous 

Mudstone, gray, mottled; reddish-brown siderite 

Sandstone, brown, hard, noncalcareous 

Sandstone, gray, soft, medium- to coarse-grained 

Mudstone, medium- to light-gray, dense; iron oxide 

Sandstone, gray-brown, medium-grained, soft, silty 

Mudstone, gray-brown, dense, micaceous, metallic luster 

Sandstone, brown, very fine grained, soft, silty 

STERLING(?) FORMATION 

Mudstone, medium- to dark-gray 

Claystone, medium-gray, hard; lithic fragments 

Claystone, gray, smooth, varved 

Sandstone, light-brown, fine-grained, silty 

Claystone, medium-gray, carbonaceous, noncalcareous 

Sandstone, brown, soft, coarse-grained, conglomerate 

Siltstone, light-brown, clayey, sandy, mottled 

Claystone, light-gray, dense, micaceous 

Sandstone, red-brown, fine- to medium-grained, clayey 

Sandstone, dark-red-brown, fine- to medium-grained 

Sandstone, red-brown, coarse- to medium-grained, soft 

Sandstone, brown, poorly sorted, clayey, pebbled 

Sandstone, red-brown, fine- to coarse-grained, pebbled 

Mudstone, gray to brown, hard, micaceous 

Mudstone, medium-gray, hard, kaolinitic, uraniferous 

Mudstone, tan, dense, kaolinitic, chalky appearance 
> ...-

0\ 

B. Chemical and mineralogical data 

Sample u Th Fe Mg Ca Ti Mn Ba Cr Cu Ni Sc Sr v 

number (ppm) (PJJITI) (percent)· - (pe!"_cent) (~rcent~ (Eercent) ~EEm) (EEm) (EEm) (EEm~ (EEm) ~EEm~ (EEm~ ~EEm~ 

TYONEK(?) FORMATION ~ 

1 5.5 6.9 3.0 1.5 0.30 0.30 300 1,500 150 70 100 30 150 150 ~ 

2 4.2 8.9 1.5 0.30 0.50 0.15 200 700 70 20 20 10 150 70 ~ 3 5.2 9.8 5.0 1.5 0.50 0.50 300 1,500 150 70 100 30 150 150 ~ 

3: 4 4.3 6.5 3.0 1.5 0.20 0.30 300 1,500 150 70 70 30 150 200 "%1 

5 4.8 10 2.0 1.5 0.30 0.30 150 1,000 150 70 50 30 150 150 ~ 6 4.1 8.1 3.0 1.5 0.30 0.30 300 1,000 100 70 70 20 150 150 0 

7 2.7 5.3 10 0.30 0.70 0.07 3,000 300 30 30 20 5.0 70 30 ·~ 

6; 8 2.6 5.5 3.0 0.70 0.10 0.20 700 700 70 30 70 7.0 70 70 ~ 

9 2.2 3.3 1.5 0.70 0.30 0.20 300 700 30 15 20 7.0 150 70 

10 4.5 10.5 2.0 1.5 0.30 0.30 100 1,000 150 70 50 20 150 150 ~ 11 2.3 3.7 0.70 0.20 0.15 0.10 70 700 30 20 15 7.0 70 70 0 

"%1 12 4.5 9.0 3.0 1.5 0.50 0.30 700 1,000 70 70 10 20 150 150 ~ 13 2.5 6.0 2.0 1.5 0.70 0.30 300 700 50 20 L 15 300 150 ~ 

Mean 3.80 7.21 3.05 1.09 0.37 0.26 517 946 92.3 48.1 46.3 17.8 143 120 ~ 

St. dev. 1.13 2.33 2.25 0.53 0.18 0.11 740 357 49.3 24.0 32.1 9.58 56.2 48.7 > 

~ 

STERLING(?) FORMATION ~ 

~ 

14 5.4 8.2 3.0 1.5 0.30 0.30 700 1,500 150 70 150 30 150 200 R 15 2.8 4.6 2.0 1.5 0.70 0.30 700 700 70 50 30 15 300 100 

16 4.2 6.5 5.0 1.5 0.30 0.30 1,500 1,500 150 100 100 30 150 150 ~ 17 5.8 1.9 3.0 1.0 0.30 0.30 300 700 70 50 70 15 150 100 en 

0 

18 2.7 7.0 3.0 0.70 0.30 0.30 30 300 30 100 30 20 150 150 ~ 

19 11 9.8 0.50 0.30 1.0 0.30 300 1,000 70 30 50 15 100 100 ~ 20 5.1 12 3.0 1.5 1.50 0.50 700 1,000 100 50 50 15 300 100 h 

tr:l 

21 3.8 6.1 5.0 1.5 0.30 0.30 700 700 150 70 70 30 200 150 z 

22 3.5 5.7 5.0 0.70 0.50 0.30 700 1,000 100 30 70 15 100 100 ;d 

23 2.6 6.0 5.0 0.70 0.50 0.20 1,500 1,000 100 50 70 15 100 150 F= 

24 2.4 6.0 5.0 0.70 0.50 0.20 700 1,000 100 50 70 15 100 100 F= 25 2.8 3.8 5.0 1.0 0.50 0.20 700 1,000 50 50 10 15 100 100 > 

26 3.3 5.0 7.0 1.0 0.50 0.20 700 1,000 70 50 70 15 100 100 en 

27 5.2 5.4 5.0 1.0 0.70 0.30 500 1,000 100 50 70 20 100 150 ~ 28 72 <16 0.50 0.20 0.70 0.30 30 500 50 50 50 30 100 70 

29 12 <6.7 2.0 0.20 0.50 0.50 50 1,500 70 200 70 30 300 200 

Mean 9.06 6.94 3.69 0.94 0.57 0.30 613 963 89.4 65.6 64.4 20.3 156 126 

St. dev. 16.5 3.30 1.78 0.46 0.31 0.09 421 330 35.4 39.7 30.4 6.72 74.7 37.4 
Sample y 'h: AI Na K Ga Yb Quartz Plag. Chlorite lllite Smectite Kaolinite 

Number ([![!m~ ([![!m~ (~rcent~ ~[!ercent) ~~rcent~ (~m) (~m~ ~in. ) (in. 

2

) (in. ~ (in.

2

) (in.

2 ) (in?) 

TYONEK(?) FORMATION 

1 30 150 7.0 0.70 3.0 20 3.0 0.29 0.04 0.12 0.08 0 0 

2 30 150 7.0 1.5 3.0 15 3.0 0.33 0.06 0.14 0.07 0 0 ~ z 

3 30 100 10 1.0 3.0 20 3.0 0.25 0.03 0.10 0.06 0 0 i!= 

4 30 150 10 0.70 3.0 30 3.0 0.28 0.02 0.12 0.07 0 0 0 

5 30 150 G 0.70 3.0 20 3.0 0.39 0.04 0.09 0 0 0 ~ 

0 

6 30 100 10 0.70 3.0 15 3.0 0.32 0.06 0.12 0.07 0 0 c 

7 15 15 1.5 0.50 0.70 10 N 0.02 0 0 0 0 0 :0 

en 8 30 70 7.0 0.30 1.5 15 1.5 0.35 0.01 0.05 0.05 0 0 c 

15 70 7.0 0.70 1.5 15 1.5 0.50 0.06 0.06 0.02 0.01 0 en 9 ~ 

10 30 100 G 0.30 3.0 30 2.0 0.30 0 0.18 0.07 0 0 ;i 

11 L 70 2.0 0.50 0.70 7.0 L 0.66 0.02 0.01 0.02 0 0 > 

r 

12 30 150 7.0 0.70 3.0 15 2.0 0.30 0.10 0.10 0.08 0 0 

13 15 100 7.0 1.0 1.5 15 1.5 0.35 0.13 0.03 0.04 0 0 ~ Mean 24.8 106 8.12 0.72 2.30 17.5 2.13 0.33 0.04 0.09 0.05 0 0 ~ St. dev. 8.08 41.1 3.86 0.31 .92 6.42 0.90 0.14 0.04 0.05 0.02 0 0 0 

STERLING(?) FORMATION sn 

14 30 150 G 1.0 3.0 20 3.0 0.34 0.06 0.04 0.03 0 0 ~ 15 30 150 7.0 1.5 1.5 15 1.5 0.44 0.07 0.06 0.03 0 0 ~ 

16 30 100 G 1.5 3.0 30 2.0 0 0.12 0.03 0.20 0.12 0 ~ m 

17 20 100 7.0 0.70 2.0 15 2.0 0.44 0.05 0.07 0.08 0 0 ~ 

z 

18 70 70 10 0.30 N 15 3.0 0.02 0.03 0 0.02 0 0.12 m 

19 15 150 7.0 0.70 1.5 15 1.5 0.55 0.04 0.03 0.05 2.00 0 z 

0 

20 30 150 7.0 1.0 1.5 15 3.0 0.33 0.11 0.03 0.02 0 0 0 

21 30 150 7.0 0.70 3.0 15 3.0 0.30 0.04 0.14 0.07 0 0 ~ 

22 10 100 7.0 0.70 2.0 15 1.5 0.36 0.08 0.08 0.03 0 0 § 23 15 100 7.0 1.0 2.0 15 2.0 0.38 0.03 0.05 0.06 0 0 ~ 

24 15 100 7.0 1.0 2.0 15 2.0 0.51 0.06 0.07 0.08 0 0 ~ 

z 

25 10 100 7.0 1.0 2.0 15 1.5 0.48 0.05 0.06 0.07 0 0 r 

26 20 200 7.0 1.0 2.0 15 2.0 0.50 0.04 0.04 0.03 0 0 m 

t-3 

27 20 150 7.0 1.0 2.0 15 2.0 0.30 0.10 0.03 0.07 0 0 to 

> 28 100 150 10 0.30 N 15 5.0 0.04 0 0 0 0 0.10 2 29 20 100 G 1.0 1.5 30 2.0 0.11 0.06 0 0 0 0.20 

Mean 29.1 126 8.72 0.90 1.87 17.2 2.31 0.32 0.06 0.05 0.05 0.13 0.03 

St. dev. 22.9 33.0 2.84 0.32 0.74 4.99 0.88 0.18 0.03 0.03 0.05 0.48 0.06 

> 

~ 

-..J 
A18 URANIUM FAVORABILITY OF TERTIARY ROCKS, SOUTII-CENTRAL ALASKA 

APPENDIX 2-MEASURED SECTIONS OF THE TYONEK(?) AND STERLING(?) 

FORMATIONS OF THE TERTIARY KENAI GROUP 

Locations of sections are shown in figure. 2. Section scales are in meters; sample numbers are circled and in bold, alongside scale. 

20 

10 

Section 1. Sterling(?) Formation. Along Cottonwood Creek 2.8 km northeast of the junction of Cottonwood and Peters Creeks. 

SE1/4NW1fitNW% sec. 33, T. 29 N., R. 8 W., Seward Meridian 

6 ·. ·?·.· · ~ ·. ·-o?> ·.":o 

.6. :? · ... ·o .. o· .o .. ." ·. 

. ·. 0 ..... 0 . o. 

0()~00~~0 0 oOo o o o~' o 

Claystone, medium- to light-gray, poorly bedded, crumbly; sandy at top, silty zones, wood fragments, horizontal 

yellowish-brown streaks, and scattered pebbles 

Sandstone, light-gray, fine- to coarse-grained; fines upward; vague bedding marked by pebble zones and lenses 

Conglomerate, light-gray; fine-grained sand matrix; fines upward from pebbles to granules; fine- to medium-grained 

lenticular sandstone interbeds, with channeled bases and tabular-planar crossbeds 

@ ---1---:>:::. :'---. ---,.....,.-,-. ;--~--•• .,.---. __ --;-. __ ----1 

..... 

Claystone, medium-gray to reddish-brown, massive; silty zones and color laminations 

Sandstone, fine-grained, and siltstone, light-brown, massive; interbedded at base and top with light-gray claystone 

0 layers 5-10 em thick 

20 

__:___, ---· ~ ___:_ ·-.--·---

Section 2. Tyonek(?) Formation. On Cottonwood Creek 1.4 km northeast of the junction of Cottonwood and Peters Creeks. 

SW%SW1/4SE% sec. 32, T. 29 N., R. 8 W., Seward Meridian 

Recent soil 

-:-·. ~.·--:-.· ~ ----;- ._--.--

Sandstone, light-brown, coarse-grained to very coarse grained; scattered granules; vague horizontal bedding; 

granule-pebble lenses 20 cm-1 m thick; clayey at top 

Conglomerate, light-brown; well-rounded pebbles 1-2 em in diameter; sand matrix; horizontal interbeds of 

medium-grained sandstone 

Conglomerate, light-brown; well-rounded pebbles 1-2 em in diameter; sand matrix; horizontal interbeds of 

medium-grained sandstone 

Coal, black, shaly; mostly covered 

Sandstone, medium-gray, fine-grained, clayey; interbedded claystone layers 5 em thick; partly covered 

Coal, black, shaly; mostly covered 

Claystone, medium-bluish-gray, crumbly; mostly covered 

Coal, black, shaly; weathers to orange streaks; wood fragments 

Claystone, medium-bluish-gray, poorly bedded, silty, crumbly; mostly covered 

Coal, black, shaly; weathers reddish brown; fibrous wood fragments 

Claystone, medium-bluish-gray, poorly bedded, silty, crumbly; mostly covered 
KENAI GROUP, SUSITNA LOWLANDS, NORTIIERN END OF COOK INLET BASIN 

Section 3. Sterling(?) Formation. On Columbia Creek 0.6 km northeast of the junction of Columbia and Cache Creeks. 

NW1ANW%NW1!4 sec. 14, T. 18 N., R. 9 W., Seward Meridian 

A19 

Conglomerate, light-grayish-brown; pebbles to cobbles; medium-grained sandstone matrix; interbedded sandstone 

lenses 2-5 em thick; fines upward to claystone; imbricated pebbles 

Sandstone, light- to reddish-brown, medium- to coarse-grained; conglomeratic at top; interbedded with granulepebble lenses; tabular-planar crossbeds 

Section 4. Sterling(?) Formation. Along Cache Creek at the junction of Cache and Trout Creeks. 

NE1ASE1,4SEIA sec. 20, T. 28 N., R. 9 W., Seward Meridian 

Conglomerate, medium- to grayish-brown; pebbles 3-5 em in diameter; poorly developed horizontal beds 1-2 m 

thick; argillaceous sandstone lenses 

Claystone, medium- to bluish-gray, massive; vague bedding 2-10m thick 

Sandstone, medium-brown, medium-grained; beds 3-20 em thick; low-angle foreset crossbeds and granule-pebble 

lenses 5-10 em thick 

Conglomerate, light- to medium-brown; pebbles to cobbles 3-20 em in diameter; grain-supported sandstone matrix, 

sequence fines upward; very low angle foreset crossbeds of longitudinal bar type 
A20 

® 

URANIUM FAVORABILITY OF TERTIARY ROCKS, SOUTII-CENTRAL ALASKA 

Section 5. Tyonek(?)Formation. On Peters Creek 2.4 km south of Petersville. Center sec. 33, T. 28 N., R. 8 W., 

Seward Meridian 

. :o: .. ...... :. ?· .. · . 

. 0 .•.• 

. . . ·. · .. ·.·. · ... ·. o· .· .. 

. . . .. 0: .· :: . . . . 

0 

. · ..... 0 . 

. . . . . . 

.... "?:. .-: .... · ..... . 

. : :_-:· . . ·~···: :o;.: :o 

Mudstone, brownish-gray 

Coal 

Mudstone, brown, crumbly; plant fragments 

Sandstone, brown-mottled, reddish-brown, fine-grained, oxidized, soft; calcareous concretions 0.2 m by 1 m at 

132.5 m, clay veins, and thinly bedded mudstone at 135.0 m 

Covered 

Claystone, medium-gray, dense, chunky; some silty beds and interbedded fine-grained sandstone and mudstone 

Coal, black, flaky 

Mudstone, brown, crumbly, sandy; carbonaceous fragments; poorly exposed 

Sandstone, gray, coarse-grained; pebbly conglomerate; discontinuous thin coal seam 
KENAI GROUP, SUSI'INA LOWLANDS, NORTIIERN END OF COOK INLET BASIN 

Section 5 (continued) 

/~ ... ": ·."·.: .... · ·.· 0 •.•. · · .. 

• 0 .: • • •. • • .' •• • • •• Sandstone, gray, coarse-grained; pebbly conglomerate; discontinuous thin coal seam 

- ....... 0 ..... . • ••• 0 0 : • •• 

: . ~ :: ·. ·>: 0 : :·~. • • • •• 0 

60- : .......... ··. · .. :·.·.· Sandstone, grayish- to light-brown, medium-grained; massive bedding 

"" Mudstone, dark-gray, flaky, very carbonaceous; coal seam at top 2 em thick 

r- ~~~~~ ~~ Coal, black, flaky 

-~ -: Mudstone, gray, crumbly 

r~~~~~~~~ 

Coal, black, flaky 

50_. •••• 

••• ••• ••• 0 

Mudstone, medium-gray, crumbly 

Coal, black, flaky 

A21 

..... ... 

40- .· ......... ··. ·. ·:·. ·.· 

Sandstone, medium-gray, fine-grained, soft, poorly sorted; flaserlike bedding, thin calcite-cemented pods at 45.0 m 

and carbonaceous partings at 46.5 m 

... ·.· .... 

• •••• • •• • 0 

••• •••• 0 •• 

. . 

. . 

: : · ... -'-. ·~: -~· 7-;- :~ 

~~--/X~:;i·:·; - . : ... . : ....... . •• 0 •••• 

. :. : 

... • • ..:........ ':.._.!. ..___ 

Sandstone, medium-gray, fine-grained; irregular carbonaceous partings and some fine-grained sandstone 

Sandstone, medium-gray, medium-grained, soft; poorly exposed; coarse-grained sand and clayey zones at various 

horizons 

Conglomerate, gray; sandy matrix 

. . . Sandstone, grayish-brown, fine- to medium-grained, soft, micaceous; poorly exposed 

~----~~~--~ 

-=-~~ ~ -=-~~~I - ~ .. :- ---~ ::__ >Claystone and mudstone, medium- to dark-gray, crumbly; thin bedded in part and dense in part; abundant 

·:s;;;;--,..,.;.:._··:: ... ~:;. carbonized wood and coal bed 15 em thick ··~··· ::: .. -:-

Coal, black, flaky ~~~-.; 

~~~~~..;. 

o ·· · · · · · · · · · · · · · Sandstone, medium-gray, very fine grained, clayey 
A22 URANIUM FAVORABILITY OF TERTIARY ROCKS, SOUTI-1-CENTRAL ALASKA 

Section 6. Tyonek(?) Formation. On the east side of Peters Creek 4.1 km south of Petersville. SEI.4NEI.4NW1.4 sec. 3, T. 27 N., 

R. 8 W., Seward Meridian 

Sandstone, light-gray, medium-grained, and interbedded pebble conglomerate, light-gray, grain-supported, 

medium-grained sand matrix 

Sandstone, light-gray, medium- to coarse-grained; weathers brown; grades upward to sandy conglomerate; granule 

lenses, drift ripples, low-angle foresets, and horizontal laminations 20 em thick 

Conglomerate, medium-gray, horizontally bedded; pebbles and cobbles 1-30 em in diameter; mudstone matrix with 

some grain support; fines upward 

Claystone, medium-gray, medium- to coarse-grained, sandy; grades upward to conglomerate 

Sandstone, light-gray, medium-grained to very coarse-grained; interbedded granule-pebble and claystone lenses 

Coal, black, clayey, woody 

Sandstone, light-gray; medium- to coarse-grained lenses and discontinuous beds of granules 0-5 em thick and 

20-30 em apart 

Conglomerate, light-gray; granules to pebbles; grain-supported matrix 

Sandstone, light-gray, medium-grained, clayey 

Coal, black, shaly, woody 

Claystone, light-gray, massive 

Coal, black, shaly; beds 5-10 em thick 

Claystone, medium-gray, silty, massive, very poorly bedded; grades laterally into coal; coal clasts and coalified 

roots; reddish-brown streaks 

Covered 

Coal, black, shaly 
70 

60 

50 

40 

30 

20 

KENAI GROUP, SUSITNA LOWLANDS, NORTIIERN END OF COOK INLET BASIN 

Section 7. Tyonek(?) Formation. On Cache Creek 1.0 km north of the junction of Cache and Spruce Creeks. 

NE%SW%SE% sec. 13, T. 27 N., R. 10 W., Seward Meridian 

Sandstone 

Coal, black, shaly; wood fragments 

Claystone; mostly covered 

Sandstone, light-gray to reddish-brown, medium- to coarse-grained; partly covered; tabular crossbeds, low-angle 

foresets, and large tabular-planar crossbeds 

Claystone, medium-gray, and interbedded sandstone, light-gray, medium- to coarse-grained; sandstone contains 

scattered pebbles and tabular-planar crossbeds 

Sandstone, medium-gray, medium- to coarse-grained; reddish-brown streaks mark horizontal beds and tabularplanar crossbeds; coarse-grained to very coarse grained granules concentrated in crossbeds 

Claystone, light- to brownish-gray, massive; horizontal laminations 1 mm-1 em thick 

A23 

Sandstone, medium- to brownish-gray, medium-grained; clayey upward; reddish-brown streaks; tabular-planar and 

trough crossbeds 1-2 m thick 

Claystone, light-gray, poorly bedded, and interbedded sandstone, 1-2 em thick, fine-grained 

Sandstone, medium-gray, medium- to coarse-grained; grades upward to claystone; coarse-grained to very coarse 

grained sand lenses, claystone clasts, scattered wood fragments, and rock fragments 

Claystone, light-gray, massive; reddish-brown streaks 

Sandstone, medium-gray, fine-grained 

Claystone, light-gray, massive; reddish-brown streaks 

Sandstone, medium-gray, medium- to coarse-grained, massive; ripple-drift crossbeds and coal fragments 

Claystone, light-gray, massive, very poorly bedded; reddish-brown streaks 

Coal, black, shaly, medium-bedded, very woody 

Claystone, medium-bluish-gray; mostly covered 
A24 URANIUM FAVORABILITY OF TERTIARY ROCKS, SOU1li-CENTRAL ALASKA 

Section 8. Tyonek(?) Formation. On west bank of Cache Creek 0.5 km north of the junction of Cache and Dollar Creeks. 

SE%NW%SE% sec. 1, T. 27 N., R. 10 W., Seward Meridian 

:: :. 

. . .. . · .. ·~ ... · .. : .. ~:· .. · 

Sandstone, medium-brown to medium-gray, fine- to coarse-grained; claystone 20 em thick at base 

Conglomerate, light-gray; abundant pebbles 2-4 mm in diameter; medium-grained, grain-supported sand matrix; 

sandstone lenses 2Q-30 em thick 

Conglomerate, light- to medium-gray, pebbles, cobbles, and scattered boulders; reddish-brown, coarse-grained, 

grain-supported sandstone matrix 

Sandstone, medium-gray, medi'um to fine-grained; wood fragments 20 em by 1 m ~uspended in sandstone; mostly 

covered 30-+~~~~--~~ ... ·.· .... . . 0. 0.. .• · .. ·.· ._. .. 

·:~ .... ·.:·:..:"-:~:.: .. ;.: 

Sandstone, medium-gray to brown, medium-grained, clayey; scattered wood fragments 

Coal, shaly, woody; fibrous plant material 

-------= 

20 - ;_~~ ~ ~~} Claystone, medium- to light-gray, massive to crumbly; reddish-brown streaks; shale at top 

Coal, interbedded with clayey coal in seams 5-10 em thick and crumbly, light-gray claystone 

Claystone, medium-bluish-gray to light-gray, crumbly; a few brown, fine- to medium-grained clayey sandstone 

lenses 

Sandstone, brown, fine- to medium-grained; woody fragments 4 by 40 em; mostly covered 

Claystone, light-gray, massive at base; reddish-brown streaks parallel with bedding; crumbly and shaly at 4.0 m; 

dark- and light-gray laminations 1-3 em thick 
KENAI GROUP, SUSI1NA LOWLANDS, NORTIIERN END OF COOK INLET BASIN 

Section 9. Sterling(?) Formation. On the east bank of Cache Creek 2.6 km south of the junction of Cache and Spruce Creeks and 5.8 km 

northeast of the junction of Cache Creek and the Kahiltna River. NW1.4SW1.4NW1.4 sec. 30, T. 27 N., R. 9 W., Seward Meridian 

Sandstone, reddish-brown, coarse-grained, crossbedded 

Conglomerate, reddish-brown, sandy 

Sandstone, light-brown, medium-grained; poorly exposed 

Mudstone, dark-gray, flaky; wood fragments including long shreds of wood at base 

A25 

Conglomerate, medium-gray; maximum grain diameter 10 em; sandstone matrix; trough-shaped sandstone lenses 

Sandstone, medium-gray, interbedded with conglomerate; maximum grain diameter 12 em; some grains have 

limonitic coating; gray conglomeratic sandstone matrix 

Conglomerate, gray; maximum grain diameter 15 em; faint large-scale crossbeds, fragments of wood, and finegrained poorly sorted sandstone lenses; clayey limonite-stained coarse-grained sandstone matrix 

Covered 
A26 URANIUM FAVORABILITY OF TERTIARY ROCKS, SOUTII-CENTRAL ALASKA 

Section 10. Tyonek(?) Formation. On the east bank of Cache Creek 2.8 km south of the junction of Cache and Spruce Creeks and 

5.6 km northeast of the junction of Cache Creek and the Kahiltna River. SW1,4NW1,4 sec. 30, T. 27 N., R. 9 W., Seward Meridian 

Sandstone, light-reddish-brown, medium-grained, well-sorted, massive 

Mudstone, medium- to light-gray 

Sandstone, light-reddish-brown, fine-grained, soft; poorly exposed 

Mudstone, gray, crumbly; plant fragments 

Sandstone, reddish-brown, fine-grained 

Siltstone, brown, soft 

Sandstone, brown, fine-grained; poorly exposed 

Coal and mudstone; poorly exposed 

Mudstone, medium-gray; poorly exposed 

Sandstone, brown with gray streaks, fine- to medium-grained; oxidized iron zones; crossbed sets 10-20 em thick 

Coal, black, flaky; wood fragments 

Mudstone, gray, micaceous, oxidized; reddish-brown at base; poorly exposed 

Sandstone, brown, medium-grained, poorly sorted, soft; no structure apparent; mostly covered by slope wash 

Coal, black, flaky; wood; two beds 10-20 em thick of light-gray, very fine grained, moderately hard sandstone 

Sandstone, gray, soft, clayey; abundant plant fragments and mica 

r:-..:....:.......:..c:...;:...:....--=--.:....::..::~..:..:..;~ Mudstone, medium-grained; grades upward to fine-grained, soft sandstone; plant fragments 

Sandstone, brown, fine-grained, soft; gray streaks; reddish-brown oxidized beds, carbonized plant fossils, and traces 

of mica 

Mudstone, medium-gray; few brown streaks 

Sandstone, gray and brown, fine-grained; irregular horizontal beds, carbonized plant matter, and mica 

Mudstone, gray, crumbly, carbonaceous 

Coal 

Mudstone, medium-gray, partly iron stained, carbonaceous, hard, flaky; thin coal bed at 34.4 m, carbonaceous 

material at 35.0 m, and scattered plant matter 

Covered 

Coal 

30 -i~ijiiiiit Mudstone, medium-gray, flaky; abundant carbonized wood fragments and 6 em thick coal bed at 31.3 m 

Covered 

Coal and interbedded mudstone 

l<c'-:._._~.:.._-=-----'-.:.._?1\ Sandstone, medium-gray, very fine grained to fine-grained, soft; fines upward to medium-gray, crumbly mudstone 

Coal, black, crumbly 

Mudstone, brown, crumbly 

Sandstone, medium-gray, fine- to coarse-grained; interbedded gray and brown oxidized clayey sandstone 
200 

190 

180 

170 

160 

150 

140 

130 

KENAI GROUP, SUSITNA LOWLANDS, NORTHERN END OF COOK INLET BASIN A27 

Section 11. Tyonek(?) Formation. On Lake Creek 6.3 km west of Shulin Lake. SW%SE1.4NW% sec. 30, T. 42 N., R. 9 W., 

Seward Meridian 

0 0 oo 0 

oo 0 0 

0 0 0 0 0 

0 0 0 0 0 0 

0 °o 0 o o 0 go Oo 0 o Ooooo0 0 0 0 0 0 0 00 0 0 0 0 

0 0 0 0 

00 0 0 0 0 0 

0 0 0 

00 0 coco 

00 0 0 0 0 0 0 0 

0 0 0 0 

0 0 0 0 0 0 0 0 0 0 0 0 0 

. ·. 0 

. ··: 0 

0 0 0 0 0 

: 0 0 0 

0 0 co o oooooo 0 0 ~ 00 00 0 0 0 0 0 

co 0 o o o c:J:.:::·.:·:·.:.·:Dooo 

0 0 0 00 0 0 0 

0 0 0 0 

oooooOO 

oOooo. 

o oo o o·o . 0 . 0 0 

o.o . 

' ... :o 

0 

Mudstone, light-medium-gray, mostly covered, contains floating pebbles and cobbles 2-20 em in diameter; zones of 

grain support 

Conglomerate, light-reddish-brown; rounded pebbles and cobbles 1-5 em in diameter; massive horizontal beds 

1-2 m thick; vague suggestion of low-angle crossbeds 

Conglomerate, light-gray; pebbles, cobbles, and boulders 1.0-2.0 min diameter; sandstone-granule matrix 

Mudstone, medium-gray, conglomeratic; granules and scattered pebbles; mostly covered 

Conglomerate, light-gray to reddish-brown; grain-supported sand matrix; pebbles and cobbles 1-40 em in diameter; 

medium- to coarse-grained sandstone lenses 5-10 em thick and 1Q-20 m long; low-angle foreset crossbeds 
A28 

® 

URANIUM FAVORABILITY OF TERTIARY ROCKS, SOUTII-CENTRAL ALASKA 

Section 11 (continued) 

Conglomerate, light-gray to reddish-brown; grain-supported sand matrix; pebbles and cobbles 1-40 em in 

diameter; medium- to coarse-grained sandstone lenses 5-10 em thick and 10-20 m long; low-angle foreset 

crossbeds 

Covered 

Claystone, light-gray, sandy; mostly covered 

Covered 

Coal to clayey coal, black, massive; seams 2-4 em thick 

Claystone and very fine grained clayey sandstone, light-gray to reddish-brown, streaked, massive 

Coal, black, channeled 

Claystone, light-gray, arenaceous, partly covered 

Sandstone and claystone interbedded with granule-pebble conglomerate, light-gray to light-reddish-brown; 

horizontal beds 1-2 m thick 

Sandstone interbedded with pebble-granule conglomerate, light-brown to light-reddish-brown, and claystone, 

light-gray, well-sorted 
@ 

KENAI GROUP, SUSITNA LOWLANDS, NORTHERN END OF COOK INLET BASIN A29 

Section 12. Tyonek(?) Formation. On the east bank of Lake Creek 3.3 km west of Shulin Lake. 

NW14NW14NEI.4 sec. 33, T. 24. N., R. 9 W., Seward Meridian 

60-.-o~o-_____ o_o_o~o--o-o~ 

0 0 0 o ~ o 0 

0

o 0 

~o;;-0 ~ 0 ~ __ o 

0 

Conglomerate, very clayey; maximum grain diameter 30 em 

0 0 ooo 0 0o 

. o: .·· 

·.~: ~:.. 6: :~. :_r/ : ·~. "_"o0

. :_o: 

·:~ ::·:·.· >·. ·.:·::_:::-_:;:E.=:'-.·9:: 

.... o·."· · .. ·.. .· .·. 

o"oooo6. .· >:/·::~:::? 

Sandstone, light-brown, pebbly; trough crossbeds as thick as 1 m, conglomerate layers in troughs; scoured base 

Sandstone, brown, fine-grained to very fine grained; iron oxide bands; gray, thin-bedded, fairly well sorted 

sandstone bed about 0.5 m from top 

Mudstone, medium-brown, flaky, soft, crumbly, dense, very sandy; medium- to dark-gray near top; carbonized wood 

fragments 

Sandstone, medium-brown, fine-grained, well-sorted, soft; horizontal beds in lower part, crossbed sets 0.7 m thick 

near top; gravel in lower part 

Conglomerate, brown, pebbly; maximum grain diameter 2 em; reddish-brown sandy matrix; scoured base 

Sandstone and conglomerate, brown, medium- to coarse-grained; crossbed sets 30 em thick; abundant mudstone 

clasts 

Sandstone, light- to medium-brown, medium-grained, conglomeratic; some near horizontal beds, low-angle 

crossbeds, and vague troughs 

Mudstone, dark-gray, sandy; fine-grained mica and carbonaceous fragments 

Conglomerate, brown, moderately hard; maximum grain diameter 7 em; grades upward to dark fine-grained 

sandstone; medium-brown, medium-grained sandstone interbeds 30 em thick 
A30 URANIUM FAVORABILITY OF TERTIARY ROCKS, SOUTII-CENTRAL ALASKA 

Section 13. Tyonek(?) Formation. On the northwest flank of Fairview Mountain above the head of Cottonwood Creek. 

SE%NE%NE% sec. 13, T. 26 N., R. 12 W., Seward Meridian 

40 ----.--0-o_o __ O_o_o_o~ 

0 oo 0 00 

0 0 0 00 0 0 0 0 Conglomerate, light-gray, medium-grained, very poorly sorted; sand matrix; pebbles and cobbles 1-20 em in 

diameter, rounded; vague horizontal bedding; mostly covered 

30 

0 0° ~ 0 0 0 0 

oOO 0 o 0 0 0 0 0 0 

Oo 0 oo Ooo~ 

. . ·.·.:~: 

·~ .. -----~ __:__ ____:__:__ __:___:__ 

.....:.....~:--.--,-~~-:-

~-:::::...·-=-·~--=-~ 

2~~~?.~ .. oo 0 ·o.·.0· 'O.o·0 .oo·0· 

:.:~·-::·.·.·~.·: 

Sandstone, light-greenish-gray, coarse-grained; fines upward; pebble conglomerate lenses 10 em thick 

Coal, black, shaly, crumbly; reddish-brown streaks and plant fossils 

Claystone, light-gray, fine-grained, sandy at base; mostly covered 

Sandstone, brown to reddish-brown; coaly lenses, granule-pebble conglomerate layers, and reddish-brown streaks 

20 -::: ..... >. .. ~:~. :.;;~:.~.~~ Conglomerate, brown; sandstone matrix; mostly covered 

Coal, black, blocky, crumbly; beds 2-5 em thick 

Claystone, medium-gray, crumbly, poorly bedded; brown to red streaks; black laminations 1 mm thick 

Sandstone, medium-gray, medium-grained; mostly covered 

Conglomerate, medium-gray; grain-supported sandstone matrix; sand lenses; mostly covered 

Conglomerate, medium-gray to reddish-brown; sandstone matrix; pebbles and cobbles 1-15 em in diameter; mostly 

covered 

Section 14. Tyonek(?) Formation. On the west flank of Fairview Mountain at the head of Cottonwood Creek. 

NE%NW%NW% sec. 7, T. 26 N., R. 12 W., Seward Meridian 

Sandstone, gray, fine-grained; mudstone layers; very poorly exposed 

Sandstone, reddish-brown, coarse-grained, soft; poorly exposed 

Conglomerate, light-brown; maximum grain diameter 15 em; gray sandstone matrix 

Coal, black, flaky to hard, laminated; poorly exposed 

Mudstone, medium-gray, very silty; sandy near base 

Conglomerate, medium-gray; grain size increases upward to cobbles; pebbles and grit near base and sandstone 

beds 15 em thick near top 

Conglomerate and sandstone, gray, coarse-grained, soft; poorly exposed 

Siltstone, gray, clayey, laminated; some mudstone 

Coal, partly hard, partly flaky, laminated 

Mudstone, gray, thin-bedded to laminated; oxidized near surface; poorly exposed in places; some very silty and 

very clayey layers 
0 

KENAI GROUP, SUSITNA LOWLANDS, NORTHERN END OF COOK INLET BASIN A31 

Section 14 (continued) 

Mudstone, gray, thin-bedded to laminated; oxidized near surface; poorly exposed in places; some very silty and 

very clayey layers 

Mudstone, medium-gray; dark-gray and carbonaceous at base; surface oxidized brown; laminated, very clayey; a 

few layers of siltstone and carbonized plant fragments at top 

Coal; lower half dense and laminated, upper part flaky 

Claystone, medium-gray, crumbly, silty; thinly bedded to laminated, micaceous intervals 

Coal, hard, dense, laminated 

Mudstone, light-medium-gray, soft, crumbly; some fine-grained mica 

Covered 

Mudstone, as above 

Sandstone, light-gray, poorly sorted; subangular grains; few dark grains 

Conglomerate, light-gray, soft, partly bedded; maximum grain diameter 3-4 em; coarse sandstone matrix; some 

horizontal bedding apparent 

Section 15. Sterling(?) Formation. On Camp Creek 0.8 km west of the junction of Camp and Pass Creeks. 

NW1.4SE%NE% sec. 29, T. 27 N., R. 12 W., Seward Meridian . 

Modern soil 

Conglomerate and sandstone, light-greenish-gray; pebbles and cobbles 1-10 em in diameter; horizontal beds of 

0~1~ conglomerate interbedded with sandstone lenses; low-angle foreset beds 

1--------...;..--_--__;l.-.. Claystone, light-orange to brown and pale-yellowish-orange, kaolinitic, uraniferous 

f-'-'-..:.....:.::..;,;.--:.:..:.::....,,:..::.:..::....:.::.::.::.~ Coal, brown; black streaks; beds 10 em thick; discontinuous 

·::·.~ ~::;.~ .. •

0

:c.:.o.•... o·.:·,··.r . :.

0

'.··:

0

·.· .... ·. ~:···,:o·_··=·.···:···:_:··.·.o.· ···~.··· ~::;l:::,::::n:·:~~:::::. 1~;ht-b•own; lnte,bedded medium- to coa.se-g•alned sandstone lenses; pebbles 

o~o_ooooog· ·o 

oo .oo9ooo·. o. 

0 0 0 0 0 

0 0 0 0 0 0 

0 0 0 0 0 0 0 0 

o 0 o o o 

0 0 0 0 

o oo ooo 

1-3 em in diameter; medium-grained grain-supported sandstone matrix; low-angle foreset beds; oxidized 

intervals 

Conglomerate, light-grayish-brown, massive; pebbles 1-5 em in diameter; medium-grained to very coarse grained 

matrix; reddish-brown streaks and scattered clasts; partly covered 
A32 

10 

URANIUM FAVORABILITY OF TERTIARY ROCKS, SOUTII-CENTRAL ALASKA 

Section 16. Sterling(?) Fonnation. On Camp Creek 0.8 km north of airstrip. SE%SE%SE% sec. 20, T. 27 N., R. 12 N., 

Seward Meridian 

Conglomerate, light-gray; grain-supported, medium- to coarse-grained sandstone matrix; low-angle foresets and 

tabular-planar crossbeds, granule lenses, and suspended pebbles in sandstone lenses 

@) --t~:-::::-c~~~~.,..;.~~Conglomerate, reddish-brown; pebbles 1-4 em in diameter; coarse-grained sandstone matrix 

~~~~~~~~-Sandstone, brown to reddish-brown, coarse-grained 

0 

Claystone, medium- to bluish-gray, massive; possibly varved 

Coal, black; reddish streaks 1-2 em thick; blocky beds 

Claystone, light- to reddish-brown; sandy lower part, silty middle part 

Sandstone and conglomerate, greenish-gray; pebbles and cobbles 1-10 em in diameter; partly covered 

Section 17. Sterling(?) Formation. On the Kichatna River on a northwest-facing cliff on the south side of the river. 

SE%NW%NE4 sec. 33, T. 24 N., R. 14 W., Seward Meridian 

.. . . . 

. •' . . . . 

Claystone, medium-gray, massive, poorly-sorted; contains floating pebbles and cobbles 

Claystone, medium-gray, blocky; beds 5-10 em thick 

Sandstone, medium-gray, massive; mostly covered 

Claystone, medium- to light-gray; very blocky, varved 

Sandstone, medium-gray, medium-grained; granule lenses, horizontal beds, low-angle crossbeds 

Claystone, medium-grained; very blocky, varved 

Sandstone, reddish-brown, coarse-grained to very coarse grained; fines upward to very fine grained sandstone 

containing granule lenses 

Conglomerate, light- to reddish-brown; pebbles and cobbles 1-20 em in diameter; coarse-grained sandstone matrix; 

a few lenses &-20 em thick of medium- and coarse-grained sandstone; a few low-angle foreset beds 
40 

KENAI GROUP, SUSITNA LOWLANDS, NORTHERN END OF COOK INLET BASIN 

Section 18. Sterling(?) Formation. On Johnson Creek on the southwest-facing cliff. SElMSWlMNW% sec. 24, T. 23 N., 

R. 14 W., Seward Meridian 

Claystone, dark-gray, crumbly, silty; very poorly sorted, vague horizontal bedding 

A33 

@ ---i~~=--=--=--..;=,j 

30 

20 

10 

0 

Conglomerate, light-brown; reddish-brown streaks; grain-supported, fine- to medium-grained sandstone matrix; 

pebbles and cobbles 1-20 em in diameter; reddish-brown, medium-grained sandstone lenses and low-angle and 

trough crossbeds 

Geology, Geochemistry, and Uranium Favorability of 

Tertiary Continental Sedimentary Rocks in the 

Northwestern Part of the Cook Inlet Area, Alaska 

By Kendell A. Dickinson, John A. Campbell, and William F. Dula, Jr. 

URANIUM FA VORABILITY OF TERTIARY ROCKS, SOUTH-CENTRAL ALASKA 

U.S. GEOLOGICAL SURVEY BULLETIN 2098-B 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1995 
CONTENTS 

Abstract........................................................................................................................... B 1 

Introduction .................................................................................................................... . 

Geology .......................................................................................................................... . 

Tertiary Sedimentary Rocks ......................................................................................... .. 

West Forelalld Formation .................................................................................... . 

Tyonek Formation ............................................................................................... .. 

Beluga Formation ................................................................................................ .. 

Methods .......................................................................................................................... . 

Statistical Analysis ........................................................................................................ .. 

Sediment Sources .......................................................................................................... .. 

Clay Minerals and Zeolites ............................................................................................ . 

Uranium Favorability .................................................................................................... .. 

Conclusions ................................................................................................................... .. 

References Cited ............................................................................................................ . 

Appendix 1-Chemical and Mineralogical Data for Samples of the 

1 

3 

3 

3 

5 

6 

6 

8 

9 

10 

12 

14 

15 

West Foreland, Tyonek, and Beluga Formations........................................................ 17 

Appendix 2-Measured Sections of the West Foreland, Tyonek, and 

Beluga Formations ....................................................................................... ;.............. 20 

FIGURES 

1. Index map of south-central Alaska showing study area.............................................................................................. B2 

2. Map showing geology of the Tyonek -Capps Glacier area and locations of measured sections................................. 4 

3. Chart showing stratigraphy of Tertiary sedimentary rocks in Cook Inlet Basin area................................................. 5 

4. Photograph showing Tyonek Formation along Coal Creek........................................................................................ 6 

5. Photographs showing Tyonek Formation near toe of Capps Glacier.......................................................................... 7 

6. Electron micrograph showing detrital texture in mudstone of the Beluga Formation ................................................ 9 

7. Photographs showing tuffaceous sedimentary rocks of the West Foreland Formation .............................................. 13 

8. Scatterplot of uranium versus thorium for samples of the West Foreland, Tyonek, and Beluga Formations............ 14 

TABLES 

1. X-ray diffractogram peaks (Cu, K-alpha radiation) measured for rock samples in the study.................................... B8 

2. Correlation coefficient matrix for data set .... .............................................................................................................. 10 

3. Varimax factor analysis for five factors...................................................................................................................... 12 

4: X-ray diffraction counts for clay minerals and zeolites for samples having high clay contents................................. 12 
Geology, Geochemistry, and Uranium Favorability of 

Tertiary Continental Sedimentary Rocks in the 

Northwestern Part of the Cook Inlet Area, Alaska 

By Kendell A. Dickinson, 1 John A. Campbell? and William F. Dula, Jr.3 

ABSTRACT 

The Paleocene and Eocene West Foreland Fonnation, 

the Oligocene and Miocene Tyonek Fonnation, and the 

Miocene Beluga Fonnation are present in the Tyonek -Capps 

Glacier area northwest of Cook Inlet, south-central Alaska. 

Several thousand feet of Tertiary continental sedimentary 

rocks having many characteristics favorable for uranium 

deposits are present in these units. These rocks consist 

mainly of mudstone, sandstone, and conglomerate that contain abundant carbonaceous material. · 

Samples of mudstone, sandstone, and conglomerate 

collected from 21localities were analyzed for uranium, thorium, and 19 other elements, and minerals were detennined 

by X-ray diffraction. Analysis of chemical and mineralogical data suggests that the primary source area for the West 

Foreland Fonnation is the Alaska Range to the northwest 

and for the Tyonek and Beluga Fonnations the Chugach and 

Kenai Ranges to the east. Smectite and zeolite fonned diagenetically from volcanic materials in the sediments. The West 

Foreland Fonnation contains more volcanic material, zeolite, and smectite than the overlying units. Although the 

potential for commercial-sized uranium deposits is low, the 

West Foreland Fonnation is believed to be more favorable 

for significant uranium deposits than the other units because 

of the greater amount of volcanic detritus within it and the 

greater amount of alteration that took place in this unit. 

INTRODUCTION 

The Cook Inlet area in south-central Alaska (fig. 1) contains a thick sequence of Tertiary continental sedimentary 

1

U.S. Geological Survey, Lakewood, Colorado. 

2

Fort Lewis College, Durango, Colorado. 

3

ARCO Exploration and Production Technology Co., Plano, Texas. 

rocks that includes, in ascending order, the Paleocene to 

Eocene West Foreland Fonnation, the Oligocene Hemlock 

Conglomerate, the Oligocene to Miocene Tyonek Fmmation, the Miocene Beluga Fonnation, and the Miocene and 

Pliocene Sterling Fonnation. Except for the West Foreland 

Fonnation, these fonnations are included in the Kenai 

Group. Interest in the possibility of uranium deposits in these 

rocks developed mainly because the sequence contains thick 

arkosic sandstone beds and abundant carbonaceous material 

and has possible sources of uranium in volcanic rocks of the 

Aleutian and Alaska Ranges to the northwest. 

Early interest in the Tertiary sedimentary rocks of Cook 

Inlet was motivated by the demand for coal. Coal resources 

of the northwestern part of the Cook Inlet area were 

described by Barnes (1966). Oil was discovered in the area 

in 1957 (Parkinson, 1962), and much of the later interest in 

the area was stimulated by the search for petroleum (Calderwood and Fackler, 1966, 1972; Crick, 1971; Kirschner and 

Lyon, 1973; Hayes and others, 1976). Interest in uranium 

during the late 1970's resulted in further study of the Tertiary 

sedimentary sequence (Croff and others, 1977; Dickinson 

and Campbell, 1978). The Beluga and Sterling Fonnations 

were described by Kremer and Stadnicky (1985) and 

Magoon and Egbert (1986). 

The area as discussed herein extends from the vicinity 

of Tyonek on the northwest shore of Cook Inlet inland northwestward along the Chuitna and Beluga Rivers to the area of 

Capps and Triumvirate Glaciers. Samples of Tertiary rocks 

were collected during a reconnaissance survey by helicopter 

between August 6 and 13, 1977. Twenty-six sections (fig. 2) 

were measured in the study area, and samples were collected. The present report is based on chemical and mineralogical analyses of the samples (appendix 1) and on the 

measured sections (appendix 2). These data provide new 

insight into the depositional and diagenetic history of these 

units as well as their favorability for uranium deposits. 

Acknowledgments. -Gary Skipp prepared oriented clay 

mineral mounts for X-ray diffraction studies and operated 

Bl 
B2 URANIUM FAVORABILITY OF TERTIARY ROCKS, SOU1H-CENTRAL ALASKA 

70'-

ALASKA 

TONZONA PLUTON 

Shirley Lakep 

Study Area 

\ 

\ 

\ 

\ 

\ 

45' 

58'~------------~~----------------------------------------------------~ 

100 200 KILOMETERS 

Figure 1. Index map of south-central Alaska showing study area (dark screen) and areas of Tertiary continental 

sedimentary rocks (unit Tc). Geology modified from Diekman (1980). 
CONTINENTAL SEDIMENTARY ROCKS, NORTIIWESTERN COOK INLET AREA B3 

the X-ray diffraction machine. Samples were chemically 

analyzed in the analytical laboratories of the U.S. Geological 

Survey at Lakewood, Colorado. Radiochemical and X-ray 

fluorescence analyses were made under the supervision of 

D.M. McKown and J.E. Taggart. X-ray spectroscopy analyses were made under the supervision of D.E. Detra and L.R. 

Layman. 

GEOLOGY 

Scattered outcrops of the Tertiary continental sedimentary rocks are present along the northwest edge of the Cook 

Inlet Basin (fig. 2) (Magoon and others, 1976). Much of the 

study area is covered by Quaternary sediments, glacial ice, 

and the waters of Cook Inlet. The area also contains Tertiary 

and Quaternary volcanic rocks of basaltic and andesitic composition, Cretaceous and Tertiary felsic igneous rocks, and 

Jurassic and Cretaceous metamorphic and sedimentary 

rocks. The Tertiary sedimentary rocks generally dip at low 

angles southeastward into the Cook Inlet Basin. 

The Cook Inlet Basin, in the coastal area of south-central Alaska, separates the Aleutian and Alaska Ranges to the 

northwest from the Kenai and Chugach Ranges to the southeast (fig. 1). The Talkeetna Mountains and the Copper River 

Basin are to the northeast. The Cook Inlet basin is about 100 

by 300 km in area; its long axis is oriented about N. 25° E. It 

contains about 8,500 m of mostly nonmarine Tertiary sedimentary rocks that comprise the Oligocene to Pliocene 

Kenai Group and the underlying Paleocene and Eocene West 

Foreland Formation (fig. 3). The Tertiary rocks overlie 

Jurassic and Cretaceous rocks (Kremer and Stadnicky, 1985) 

and underlie Quaternary aliuvium and glacial deposits. 

The Cook Inlet Basin is generally bounded on the east 

by the Border Ranges fault (Knik fault of Magoon and others, 1976), which trends about N. 30° E. (fig. 1). The Bruin 

Bay fault, which forms the western margin of the basin, 

extends northward about N. 45° E. It intersects the Castle 

Mountain fault in the northern part of the basin. The Castle 

Mountain fault trends about N. 60° E. and generally forms 

the northwestern boundary ·of the basin (fig. 1). Undifferentiated lithic equivalents of the Kenai Group and the West 

Foreland Formation extend north of. the Castle Mountain 

fault into the Susitna Lowlands. Other minor faults and lineaments have been mapped on the Kenai Peninsula. Several 

anticlines and synclines, whose axes approximately parallel 

the long axis of the basin, were mapped by Magoon and others (1976) in the eastern half of the Cook Inlet Basin. Water 

of Cook Inlet covers most of the northwest half of the basin. 

TERTIARY SEDIMENTARY ROCKS 

Tertiary sedimentary rocks of the Cook Inlet Basin 

were named the Kenai Group by Dall and Harris (1892), who 

assigned the group to the Miocene. Barnes and Cobb (1959) 

and Parkinson (1962) called these same rocks the Kenai 

Formation. Subsequently, the Kenai Group was divided into 

five formations, in ascending order, the West Foreland Formation, Hemlock Conglomerate, Tyonek Formation, Beluga 

Formation, and Sterling Formation (Calderwood and Fackler 

1966, 1972; Crick, 1971). Later, Magoon and others (1976) 

removed the West Foreland Formation from the Kenai 

Group (fig. 3). 

In the study area the Tertiary sequence, in ascending 

order, consists of the West Forelan~ Formation (Paleocene 

and Eocene) and the Tyonek (Oligocene and Miocene) and 

Beluga (Miocene) Formations of the Kenai Group (fig. 3). 

The Hemlock Conglomerate was not identified, and the Sterling Formation does not crop out in the Tyonek -Capps Glacier area. Basal rocks of the Kenai Group are separated in 

places from the underlying West Foreland Formation by an 

angular unconformity. 

WEST FORELAND FORMATION 

The Paleocene and Eocene West Foreland Formation 

consists mostly of claystone and tuffaceous sandstone at the 

type section, which was established by CalderWood and 

Fackler (1972) in the subsurface in Pan American Oil Company's West Foreland no. 1 well, in sec. 21, T. 8 N., R. 

14 W., Seward Meridian. The thickness at the type section, 

which is at West Foreland on the west shore of Cook Inlet 

about 25 km south of the study area, is 271m. In the study 

area the Hemlock Conglomerate has not been identified, and 

the West Foreland is unconformably overlain by the Tyonek 

Formation. In some areas the West Foreland Formation 

overlies the Paleocene Arkose Ridge Formation (Magoon 

and others, 1976), but at the type section and in the report 

area it unconformably overlies Jurassic rocks (Calderwood 

and Fackler, 1972; Kremer and Stadnicky, 1985). 

About two-thirds of the outcrops of the West Foreland 

Formation in the study area consists of brown to grayishbrown polymictic conglomerate. The remaining one-third 

consists mostly of light-brown lithic sandstone but also 

includes small amounts of claystone and coal (sections 1-9, 

appendix 2). The conglomerate clasts are mostly granite, 

volcanic rocks, and metamorphic rocks (Adkison and others, 

1975). Barnes (1966) reported a tuff bed more than 9 m thick 

in the southern part of the study area. An ash bed 7 m thick 

is also present at the type section (Calderwood and Fackler, 

1976). The volcanic beds were not sampled for this study. 

Descriptions of the West Foreland are given in Barnes 

(1966), who considered it part of the Kenai Formation, and 

in Adkison and others (1975) and CalderwoOd and Fackler 

(1972). 

In the study area the West Foreland was deposited primarily as alluvial fans. The massive conglomerate beds were 

deposited close to the mountain front and may have formed 

as debris flows on alluvial fans while uplift was occurring. 

The remaining sandstone and mudstone beds are fluvial 

deposits. 
61

°30' 

Os 

~Kgd 

(7ook Inlet 

Tb 

0 5 10 20 30 KILOMETERS 

I I I I I I I I I I I I I 

Qs 

tc 

~ 

c::: 

i 

s: 

'Tl 

~ 0 

:;11:1 

6; 

~ 0 

'Tl 

~ ~ 

R 

~ 

~ c::: 

:d 

h 

m 

~ ~ 

~ ~ 
tl 

I'C:l 

"E 

0 

u 

CONTINENTAL SEDIMENTARY ROCKS, NORTHWESTERN COOK INLET AREA B5 

C7l 

• 

Age Unit 

Quaternary Alluvium and glacial deposits 

Pliocene 

Sterling 

Formation 0. 

Miocene ::J 

e Beluga Formation 

(.9 

'co 

c Tyonek (!) 

~ Formation 

Oligocene 

Hemlock Conglomerate 

Eocene West Foreland 

Formation 

Paleocene 

Arkose Ridge Formation 

Mesozoic and older rocks 

Figure 3. Stratigraphy of Tertiary sedimentary rocks in Cook Inlet Basin area. Ages from Magoon and others (1976). 

TYONEK FORMATION 

The type section of the Tyonek Formation designated 

by Calderwood and Fackler (1972) is the sequence from 

1,311 to 3,642 m depth in the Pan American Petroleum Corporation's Tyonek State 17587 Number 2 well in sec. 30, 

T. 11 N., R. 11 W., Seward Meridian. Almost two-thirds of 

this 2,331-meter-thick unit consists of massive gray fme- to 

medium -grained sandstone and interbedded gray claystone. 

The remainder of the unit consists mostly of light-to darkgray partly carbonaceous thin-bedded claystone. The 

Tyonek was placed in the Seldovian (provincial) Stage by 

Wolfe and others (1966). The Tyonek conformably overlies 

the Hemlock Conglomerate and is conformably overlain by 

the Beluga Formation. 

Measured sections of the Tyonek Formation in the 

study area are about 45 percent sandstone, 40 percent claystone or mudstone, and 15 percent coal (sections 10-16, 

appendix 2). The sandstone is light gray or brown and fine to 

medium grained, the claystone is light to medium gray, and 

the coal is black and flaky or shaly. Typical sequences are 

fming upward, generally starting with crossbedded mediumto coarse-grained sandstone at the bottom, extending upward 

into mudstone or claystone, and, fmally, to coal (figs. 4, 5). 

According to Hite (1976) the Tyonek was deposited in a 

poorly drained alluvial valley. The fining-upward sequences 

probably represent deposition in and near meandering fluvial 

channels. 
B6 URANIUM FAVORABILITY OF TERTIARY ROCKS, SOUTI-1-CENTRAL ALASKA 

Figure 4. Tyonek Formation along Coal Creek 3 km north of Beluga Lake. Near measured section 13 (fig. 2, appendix 2). 

BELUGA FORMATION 

The type section of the Beluga Formation consists of 

1,265 m of thin interbedded sandstone, siltstone, claystone, 

and lignitic to subbituminous coal. The type section is the 

Beluga River No. 1 well in sec. 35, T. 13 N., R. 10 W., 

Seward Meridian, drilled in 1962 by Standard Oil Company 

of California at the village of Beluga (fig. 2) (Crick, 1971; 

Calderwood and Fackler, 1972). The composition of the Beluga at the type section is similar to exposures near Homer at 

the south end of the Kenai Peninsula (Adkison and others, 

1975). Rock types similar to those of the type section are 

present in the Deep Creek Unit well on the Kenai Peninsula 

(Adkison and Newman, 1973). Outcrops of the Beluga on 

the Kenai Peninsula were assigned to the Homerian (provincial floristic) Stage by Wolfe and others (1966). Wolfe and 

Tanai (1980) determined that these rocks are middle and late 

Miocene in age based mainly on plant fossils. 

Outcrops of the Beluga Fonnation in the lower reaches 

of the Chuitna and Beluga Rivers consist of mudstone and 

claystone, sandstone, conglomerate, and coal in order of 

decreasing proportions (sections 17-21, appendix 2). The 

mudstone and claystone are medium gray and are intercalated with thin wavy beds of coal and carbonized plant 

debris. The sandstone is light gray to brown, fine to coarse 

grained, and partly crossbedded and has a clayey matrix. 

The formation was probably also deposited on a poorly 

drained alluvial plain, but fming-upward sequences are 

lacking and the units are thicker than those in the Tyonek 

Formation. 

METHODS 

Nine sections of the West Foreland Fonnation, seven 

sections of the Tyonek Formation, and five sections of the 

Beluga Formation were described and sampled (fig. 2, 

appendix 2). Twenty-eight samples, intended to be representative of the formations, were collected. Samples were collected from the predominant litologic types at each measured 

section. The samples were analyzed for 21 elements and 6 

minerals (appendix 1). Sample localities are shown in figure 

2 and in measured sections in appendix 2. 

Uranium and thorium contents of the samples were 

determined using the delayed-neutron method (Millard, 

1976). Elemental abundances were determined using sixstep semiquantitative spectroscopy (Myers and others, 

1961). Beryllium, boron, and lead were omitted in the statistical calculations because of the large number of qualified 

values in these analyses. Mineralogical determinations were 

made by X-ray diffraction of whole-rock cell mounts. Oriented mounts of the <2-micron clay fractions for a few samples were X-rayed after air-drying, glycolation, and heating 

to 550°C. The whole-rock X-ray diffraction data were 

obtained under conditions made as uniform as possible for 

all of the runs. The same preparation procedures and instrument settings were used for all samples. All the runs were 

made continously, and a standard sample was X-rayed 

before and after each daily run. All analyses were made from 

sample splits. 

The relative abundances of quartz, feldspar, chlorite, 

illite, smectite, and a zeolite were determined by measuring 
CONTINENTAL SEDIMENTARY ROCKS, NOR1HWESTERN COOK INLET AREA B7 

Figure 5. Tyonek Formation near toe of Capps Glacier. Fining-upward sequences containing coal 

beds (dark layers) at the top of each sequence. Near measured section 14 (fig. 2, appendix 2).A, Outcrop is approximately 80 m thick. B, Closer view of A. Sequence is about 20m thick. 

the areas of selected X-ray diffraction peaks (in square 

inches) as recorded on the whole-rock diffractograms. The 

zeolite is clinoptilolite or heulandite and perhaps a mixture 

of the two. Illite, as detetmined, includes mica and the clay 

mineral illite. The peaks measured for each mineral are listed 

in table 1. The areas of individual X-ray diffraction peaks 

provide estimates of the relative abundances of minerals. 

The data do not, however, represent the absolute abundances 

of minerals. Two thin sections also were made, and two samples of clay-bearing mudstone were examined using a scanning electron microscope. 

A factor analysis was calculated using a conunercial 

program (Hintze, 1992). The analysis suggests many interesting relationships that otherwise might be missed when 

perusing the data. Some of the results, however, seem to defy 

interpretation; this may reflect lack of randomness in sample 
B8 URANIUM FAVORABILI1Y OF TERTIARY ROCKS, SOUTII-CENTRAL ALASKA 

Table 1. X-ray diffractogram peaks (Cu, Ka radiation) 

measured for the rock samples in the study. 

X-ray diffraction Crystallographic 

Mineral peak (degrees 28) index 

Feldspar 26.9-27.9 002 

Quartz 20.8 100 

Illite 8.8 001 

Smectite 10.2 002 

Chlorite 12.5 002 

Clinoptiloliteheulandite 9.8 800 

collection, too few samples, or various degrees of departure 

from normal distribution of the data. 

STATISTICAL ANALYSIS 

Mineralogical and chemical data for the West Foreland, 

Tyonek, and Beluga Formations in the Tyonek -Capps Glacier area are given in appendix 1. Arithmetic means and standard deviations are given for the minerals and elements for 

each of the three stratigraphic units. A correlation coefficient 

matrix (table 2) and a five-factor model of an R-mode factor 

analysis (table 3) (Harmon, 1960) are presented for the data 

in appendix 1. The degree of correlation for all pairs of variables is shown by the correlation coefficients. The purpose 

of the factor analysis is to group related variables to reduce 

the amount of variation that must be interpreted and to investigate the underlying causes. The factors are calculated from 

the correlation matrix. The factor analysis includes the varimax rotation, which is rotation of the factors around the 

orthogonal axes. Varimax rotation enhances differences in 

factor loadings (Hintze, 1992). Factor loadings are the correlations between each variable and the factors. The sum of the 

squares of the factor loadings for each variable is equal to the 

communality, the proportion of each variable explained by 

the analysis. For more complete descriptions of factor analysis and its geological application see Davis (1986) and 

Koch and Link ( 1971 ). A five-factor analysis was chosen for 

presentation because of its relative simplicity and because 

reasonably high communalities were obtained for the variables of primary interest including uranium, thorium, smectite, and chlorite. 

The geologic conditions that control the calculated factors are believed to be source area, sorting and alteration during transport and deposition, and postdepositional alteration 

(diagenesis). Differences in mineralogical and chemical 

makeup of rocks of the source area result in differences in the 

composition of the sediments produced. During transport, 

the sediments are sorted into finer clay and coarser feldspathic and lithic sand. Chemical and mineralogical alteration 

may also occur during sediment transport. Diagenesis, such 

as alteration of volcanic materials to clay and zeolite, may 

also result in differences in mineralogical and chemical 

makeup of the rocks. The calculated factors represent combinations of the above processes that in some cases make 

interpretation speculative. 

Factor one.-Factor one consists of Th, Yb, U, Y, AI, 

K, Ga, Sc, and Zr (table 3). Uranium and thorium are in minerals such as monazite or uranothorianite that are commonly 

present in heavy-mineral concentrates. This factor probably 

represents sandstone and conglomerate that have concentrations of heavy minerals. Many examples of uranium and thorium concentration-s have been found in heavy-mineral' 

deposits in modern stream sediments in Alaska (Eakins, 

1969). Yttrium and ytterbium are rare earth elements commonly present in monazite, a placer constituent Zirconium 

is present in zircon, which is also common in placer concentrates. Potassium, gallium, scandium, and aluminum are concentrated in the silicate phases that are present in sandstone 

and conglomerate. 

Factor two.-Factor two consists of copper, illite, chlorite, nickel, vanadium, and chromium (table 3). This factor 

apparently represents fine-grained sediments from a terrane 

rich in metamorphic and basic igneous rocks. According to 

Hayes and others (1976), illite and chlorite in the Beluga 

Formation on the Kenai Peninsula suggest a sediment source 

from metamorphic rocks in the Chugach Mountains. Illite 

and chlorite are also concentrated in the finer grained mudstone and claystone. The copper, nickel, and chromium commonly are present together in sulfide minerals and suggest a 

mafic source of the sediments. Vanadium is associated with 

carbonaceous materials, abundant in most of these rocks but 

more abundant in the Tyonek and Beluga Formations than in 

the West Foreland Formation (appendix 1). ·· 

Factor three.-Factor three contains smectite, iron, 

strontium, and titanium (table 3). Smectite apparently 

formed diagenetically from volcanic materials either before 

or after deposition of the sediments (fig. 6). The occurrence 

of strontium in this factor suggests that the strontium may 

have been involved in the diagenetic alteration, perhaps in 

the smectite as an exchangeable cation. Iron and titanium are 

present together in the mineral ilmenite, a heavy-mineral 

constituent. The association of ilmenite with smectite and 

strontium in this sample set is not understood. 

Factor four.-Factor four includes calcium, manganese, and magnesium at the positive pole and barium at the 

negative pole (table 3). The calcium, manganese, and magnesium probably represent plagioclase and chlorite from a 

predominantly mafic source. Barium may have substituted 

for potassium in feldspar from a more felsic source. A relatively strong secondary loading of barium in factor five suggests involvement in diagenesis. 

Factor five.-Factor five contains zeolite, feldspar, and 

sodium with positive loadings and quartz with a negative 

loading (table 3). This factor probably represents feldspathic 

volcanic clastic rocks in which zeolite has grown in the interstices (fig. 6). The relatively low primary loading and 
CONTINENTAL SEDIMENTARY ROCKS, NORTIIWESTERN COOK INLET AREA B9 

Figure 6. Electron micrograph showing detrital texture in mudstone of the Beluga Formation. Sample 2 (table 4, appendix 1). 

communality for sodium indicate that the distribution of 

sodium is not well explained by the factor model. The presence at the opposite pole of quartz, which is complexly distributed among most sediments, suggests, perhaps, that the 

sediment source high in volcanic materials was low in quartz 

or that quartz was dissolved during diagenesis. 

SEDIMENT SOURCES 

Some obviously important sediment sources for the 

various Tertiary stratigraphic units in the Cook Inlet Basin 

are the Aleutian and Alaskan Ranges to the northwest and 

the Kenai and Chugach Ranges to the southeast (Hayes and 

others, 1976). Other possible sources include the ancestral 

drainages of the Matanuska and Susitna Rivers (fig. 1), 

which drain the Talkeetna Mountains and the Copper River 

Basin. All of these sources probably contributed sediments 

to the Tertiary stratigraphic units during the Tertiary; however, certain generalizations can be made as to the relative 

importance of each (Dickinson and Skipp, 1992). The Aleutian-Alaskan Ranges source has been characterized as granitic and felsic volcanic in character and the Kenai-Chugach 

Ranges source as metamorphic in character (Hayes and others, 1976). Heavy minerals also have been used to distinguish the two major sediment source areas (Hite, 1976; 

Biddle, 1977). The Aleutian-Alaska Ranges sediment 

sources contain more hornblende and the Kenai-Chugach 

Ranges sources contain more epidote and possibly more 

garnet. The heavy-mineral contributions of the Talkeetna 

Mountains and the Copper River Basin sources are 

unknown. 

The distribution of minerals and elements in the data for 

the study area suggests that the Beluga and Tyonek Formations received their sediments primarily from the Kenai and 

Chugach Ranges to the southeast and that the West Foreland 

Formation received its sediments primarily from the Aleutian and Alaska Ranges to the northwest. The low chloriteillite content and the volcanic component in the West Foreland (appendix 1) suggest ·the Aleutian-Alaskan Ranges 

source to the northwest. If the West Foreland Formation was 

deposited on alluvial fans near the mountain front, the sediment source would have necessarily been the AleutianAlaska Ranges. On the other hand, if we follow Hayes and 

others (1976), the high chlorite and illite content in the 

Tyonek and Beluga Formations suggests a predominant sediment source in the Kenai-Chugach Ranges to the southeast. 

The setting of the surrounding terrane and the location of the 

deposits suggest that the source was valleys drained by the 

ancestral Susitna and Matanuska Rivers. Either of these 

areas could have supplied a large variety of .igneous, metamorphic, and sedimentary source materials. 

Certain chemical and mineralogic differences are noted 

between the stratigraphic units described herein. Based on 

the data presented in appendix 1, the West Foreland Formation is different from the Kenai Group in that it contains 

more postassium, gallium, uranium, thoriium, ytterbium, 

sodium, barium, feldspar, smectite, and zeolite and less 
BlO URANIUM FAVORABILTIY OF TERTIARY ROCKS, SOU1H-CENTRAL ALASKA 

Table 2. Correlation coefficient matrix for data. 

[Data set isgiven in appendix 1] 

Uranium Thorium Iron Magnesium Calcium Titanium 

Uranium 1.00 

Thorium 0.81 1.00 

Iron 0.35 0.29 1.00 

Magnesium -0.11 -0.11 0.38 1.00 

Calcium -0.31 -0.39 0.12 0.35 1.00 

Titanium 0.27 0.32 0.66 0.28 0.07 1.00 

Manganese -0.09 -0.17 0.34 0.37 0.64 0.17 

Barium 0.47 0.30 0.27 -0.29 -0.48 0.15 

Chromium 0.37 0.29 0.24 0.07 -0.12 0.32 

Copper 0.48 0.30 0.42 0.27 0.11 0.49 

Nickel 0.39 0.36 0.47 0.38 -0.11 0.54 

Scandium 0.46 0.41 0.71 0.37 0.15 0.86 

Strontium -0.30 -0.32 0.35 0.14 0.27 0.32 

Vanadium 0.51 0.37 0.61 0.35 -0.05 0.72 

Yttrium 0.63 0.65 0.70 0.21 -0.07 0.58 

Zirconium 0.26 0.49 -0.05 -0.25 -0.15 0.10 

Aluminum 0.58 0.58 0.74 0.16 -0.03 0.69 

Sodium 0.07 0.11 0.19 0.03 0.26 0.41 

Potassium 0.75 0.60 0.34 -0.18 -0.20 0.27 

Gallium 0.78 0.64 0.32 -0.11 -0.12 0.40 

Ytterbium 0.65 0.68 0.52 -0.04 -0.10 0.42 

Quartz -0.32 -0.09 -0.53 -0.03 -0.33 -0.45 

Feldspar -0.04 -0.02 -0.08 -0.16 -0.03 -0.04 

Illite 0.26 0.12 0.18 0.31 -0.12 0.25 

Chlorite 0.34 0.11 0.08 0.14 -0.07 0.11 

Smectite -0.08 -0.02 0.34 0.06 0.12 0.24 

Zeolite -0.10 -0.05 0.13 -0.13 0.06 0.11 

Manganese Barium Chromium Copper Nickel Scandium 

Manganese 1.00 

Barium -0.33 1.00 

Chromium 0.10 0.08 1.00 

Copper 0.30 0.20 0.64 1.00 

Nickel 0.15 0.19 0.68 0.78 1.00 

Scandium 0.25 0.13 0.34 0.50 0.55 1.00 

Strontium 0.05 0.05 -0.33 -0.23 -0.37 0.28 

Vanadium 0.20 0.19 0.63 0.83 0.77 0.74 

Yttrium 0.17 0.35 0.20 0.31 0.43 0.73 

Zirconium -0.16 0.17 -0.27 -0.29 -0.30 0.05 

Aluminum 0.12 0.30 0.19 0.31 0.36 0.79 

Sodium 0.14 0.07 -0.03 0.11 0.06 0.37 

Potassium -0.10 0.37 0.24 0.31 0.19 0.42 

Gallium -0.05 0.26 0.30 0.38 0.18 0.56 

Ytterbium -0.01 0.41 -0.11 -0.01 0.05 0.55 

Quartz -0.20 -0.32 0.10 -0.30 0.04 -0.51 

Feldspar -0.11 0.10 -0.44 -0.28 -0.33 -0.03 

Illite 0.15 0.09 0.67 0.68 0.73 0.27 

Chlorite 0.14 0.22 0.58 0.68 0.59 0.23 

Smectite -0.06 0.18 -0.24 -0.27 -0.24 0.23 

Zeolite -0.09 0.30 -0.34 -0.03 -0.30 -0.13 

manganese, chromium, copper, vanadium, chlorite, and CLAY MINERALS AND ZEOLITES 

illite. These differences, although slight for some minerals or 

elements, reflect differences in source area, lithology, and 

alteration of the sediments during transport or after 

deposition. 

Clay minerals in the Kenai Group and West Foreland 

Formation in the Cook Inlet Basin can be divided into detrital and diagenetic groups (table 4). The zeolite, which 
CONTINENTAL SEDIMENTARY ROCKS, NORTHWESTERN COOK INLET AREA Bll 

Table 2. Correlation coefficient matrix for data set-Continued. 

Strontium Vanadium Yttrium Zirconium Aluminum Sodium 

Strontium 1.00 

Vanadium -0.01 1.00 

Yttrium 0.09 0.44 1.00 

Zirconium 0.17 -0.28 0.30 1.00 

Aluminum 0.26 0.60 0.72 0.22 1.00 

Sodium 0.18 0.05 0.40 0.40 0.35 1.00 

Potassium 0.07 0.41 0.56 0.35 0.63 0.22 

Gallium 0.07 0.50 0.49 0.35 0.66 0.18 

Ytterbium 0.17 0.16 0.81 0.55 0.75 0.39 

Quartz -0.49 -0.28 -0.50 -0.10 -0.50 -0.40 

Feldspar 0.26 -0.21 0.09 0.40 0.10 0.40 

Illite -0.34 0.68 0.05 -0.32 0.02 -0.14 

Chlorite -0.46 0.51 0.03 -0.42 0.05 -0.18 

Smectite 0.48 -0.12 0.26 0.15 0.16 0.04 

Zeolite 0.41 -0.25 0.10 0.40 -0.08 0.30 

Potassium Gallium Ytterbium Quartz Feldspar Illite 

Potassium 1.00 

Gallium 0.68 1.00 

Ytterbium 0.61 0.56 1.00 

Quartz -0.41 -0.40 -0.53 1.00 

Feldspar 0.30 -0.04 0.25 -0.36 1.00 

Illite 0.01 0.08 -0.29 0.24 -0.41 1.00 

Chlorite -0.01 0.21 -0.21 -0.01 -0.48 0.67 

Smectite -0.27 0.06 0.34 -0.38 0.02 -0.31 

Zeolite 0.09 -0.03 0.20 -0.45 0.28 -0.44 

Chlorite Smectite Zeolite 

Chlorite 1.00 

Smectite -0.34 1.00 

Zeolite -0.40 0.33 

probably is mostly heulandite but may also contain some 

clinoptilolite, is diagenetic. 

Chlorite and illite are interpreted as detrital in origin 

because they are abundant in the unconsolidated, unaltered, or slightly altered rocks of the Tyonek and Beluga 

Formations and common in the West Foreland Fonnation 

over a wide area, and because they are abundant in the 

Chugach-Kenai Ranges source rocks (Hayes and others, 

1976; Dickinson and Skipp, 1992). In addition, they display a detrital texture in electron micrographs (fig. 6). 

Chorite and illite are strongly correlated in the sample set 

(r=+0.67, table 2), probably because both chlorite and 

illite were deposited in the fine-grained fraction of the fluvial mudstone and claystone. 

Some of the smectite may also be detrital, but most of 

it fonned diagenetically from tuffaceous material originally 

a part of the sediments. Volcanic grains in the mudstone are 

coated by smectite in the West Foreland Formation (fig. 7). 

Smectite bas a negative correlation with chlorite (r=-0.34) 

and illite (r=-0.31) (table 2) in the sample set (appendix 1). 

This relation could not be explained if the smectite was 

deposited as part of the fme fraction of the detrital component; therefore, much of the smectite must be diagenetic. 

1.00 

Abundant kaolinite and small amounts of montmorillonite (smectite), together with mixed-layer (layers not specified) clay, have been reported from the Capps and Chuitna 

coal fields (Odum and others, 1988). The absence of kaolinite in the samples of this report is probably because the 

kaolinite is in rocks related to the coals, and samples of these 

rocks were not analyzed for clay minerals. 

The zeolites, which consist of clinoptilolite and (or) 

heulandite, are in the interstices of sandstone and mudstone 

and are diagenetic (fig. 7). X-ray energy-dispersive spectrometry indicates that the zeolite is rich in calcium relative 

to potassium, which favors heulandite rather than clinoptilolite. 

In the study area (fig. 1) the West Foreland Fonnation 

contains more volcanic material than do units of the overlying Kenai Group (Adkison and others, 1975; Magoon and 

others, 1976, Croff and others, 1977), and it also contains 

more zeolite and smectite (table 4, appendix 1). The West 

Foreland contains less chlorite and illite than do the overlying units. Perhaps some smectite and zeolite formed from 

the volcanic component of the sediments, and the sediments were diluted by illite- and chlorite-barren volcanic 

materials. 
B12 URANIUM FAVORABILITY OF TERTIARY ROCKS, SOU1H-CENTRAL ALASKA 

Table 3. Varimax factor analysis for five factors. 

[Primary factor loadings are underlined] 

Factor 1 Factor 2 Factor 3 Factor 4 Factor 5 Communality 

Uranium 0.81 0.34 -0.11 -0.27 0.03 

Thorium 0.87 0.11 -0.09 -0.24 -0.18 

Iron 0.44 0.33 0.66 0.19 0.13 

Magnesium -0.03 0.26 0.37 0.56 -0.22 

Calcium -0.20 -0.05 0.09 0.80 0.25 

Titanium 0.46 0.38 0.54 0.22 0.17 

Manganese -0.01 0.19 0.05 0.76 0.09 

Barium 0.26 0.22 0.21 -0.70 0.36 

Chromium 0.19 0.76 -0.10 -0.02 -0.18 

Copper 0.22 0.89 -0.03 0.13 0.24 

Nickel 0.28 0.82 0.09 0.09 -0.18 

Scandium 0.62 0.39 0.48 0.32 0.07 

Strontium -0.06 -0.31 0.64 0.14 0.42 

Vanadium 0.40 0.81 0.24 0.12 0.02 

Yttrium 0.79 0.14 0.37 0.08 0.09 

Zirconium 0.55 -0.53 -0.11 -0.12 0.18 

Aluminum 0.79 0.17 0.38 0.12 0.09 

Sodium 0.38 -0.11 -0.02 0.35 0.52 

Potassium 0.77 0.13 -0.18 -0.14 0.33 

Gallium 0.76 0.20 0.02 -0.10 0.12 

Ytterbium 0.86 -0.23 0.30 -0.07 0.15 

Quartz -0.33 -0.06 -0.40 -0.12 -0.73 

Plagioclase 0.18 .45 -0.15 0.04 0.54 

Illite -0.01 0.84 -0.08 0.03 -0.24 

Chlorite -0.03 0.83 -0.17 -0.07 -0.09 

Smectite 0.01 - 0.32 0.80 -0.11 0.03 

Zeolite -0.06 -0.29 0.24 -0.20 0.69 

Table 4. X-ray diffraction counts of oriented, glycolated mounts for clay minerals and zeolites from samples having 

high clay contents. 

[Sample descriptions, analyses, and locations are given in appendixes 1 and 2. Cystallographic index for peak measured is given in 

parentheses (table 1). Leaders ( --) indicate peak not detected] 

Sample Stratigraphic 

number unit 

Beluga Formation 

2 Beluga Formation 

9 Tyonek Formation 

12 Tyonek Formation 

21 West Foreland Formation 

22 West Foreland Formation 

24 West Foreland Formation 

Smectite Illite 

(001) (001) 

113 63 

79 116 

100 45 

127 48 

139 28 

87 

656 28 

Chlorite 

(002) 

123 

255 

54 

230 

27 

24 

Zeolite and (or) 

heulandite (800) 

106 

29 

0.86 

0.87 

0.80 

0.57 

0.76 

0.73 

0.63 

0.78 

0.65 

0.92 

0.80 

0.88 

0.70 

0.88 

0.79 

0.65 

0.83 

0.54 

0.77 

0.64 

0.90 

0.82 

0.55 

0.76 

0.73 

0.75 

0.66 

URANIUM FAVORABILITY 

Tertiary sedimentary rocks in the study area probably 

have relatively low favorability for uranium deposits. This 

estimation is based on lack of evidence for widespread alteration of the potential host rocks in the study area and the lack 

of known uranium deposits. The high correlation between 

uranium and thorium (fig. 8, table 2) and the low ThiU ratio 

( <2 for each of the three formations) are regarded as unfavorable. The Utrh ratio is erratic in rocks that have been subjected to epigenesis because uranium is mobilized by 

oxidizing ground water and thorium is not. The uranium 

content of the samples analyzed for this study ranges from 

2.0 to 4.9 ppm for the West Foreland F01mation, from 1.4 to 

5 ppm for the Tyonek Formation, and from 1. 7 to 4.9 ppm 

for the Beluga Formation (appendix 1). 

The West Foreland Formation may have a slightly 

higher favorability for uranium deposits in the study area 

than the overlying Tyonek and Beluga Formations. The 

West Foreland Formation has a more granitic and felsic volcanic source than the Tyonek and the Beluga. In addition, 

more samples of the West Foreland contain diagenetic minerals, especially montmorillonite and zeolite (table 4, appendix 1). The presence of diagenetic minerals in the West 
CONTINENTAL SEDIMENTARY ROCKS, NORTI-IWESTERN COOK INLET AREA B13 

Figure 7. Tuffaceous sedimentary rocks of West Foreland Formation. A, Photomicrograph showing zeolite crystals that grew in interstices of tuffaceous sandstone. Sample 27 

(table 4, appendix 1). B, Electron micrograph of siltstone showing zeolite (1) and smectite 

(2). Sample 22 (table 4, appendix 1). 

Foreland Formation increases the likelihood that epigenetic 

uranium mineralization occurred in these rocks. 

The overall favorability for uranium in the Cook Inlet 

Basin was rated as low by Croff and others (1977). They 

stated (p. 3, v. 1), however, "that certain formations contain 

favorable environments for sandstone-type uranium deposits." Of the formations studied herein, they ranked the 

Tyonek Formation frrst in uranium favorability, the West 

Foreland Formation second, and the Beluga Formation third. 

Their ratings were based on numerous factors including geologic age, depositional environment, provenance, and lithofacies of potential host rocks. Dickinson and Campbell 

(1978) rated the undivided Kenai Group and the West Foreland Formation in the Tyonek -Capps Glacier area higher in 

uranium favorability than corresponding rocks on the Kenai 

Peninsula and lower than generally correlative rocks in the 
B14 URANIUM FAVORABILITY OF TERTIARY ROCKS, SOU1H-CENTRALALASKA 

12 ,-------,--------,-------.--------~------~-------.--------~----~~------~ 

• I 

10 I-

+ * z 

0 8 - ::J 

_J * ~ 

c:r:: 

L.U 

a... 

(J) + + 1-

c:r:: 6 I--

<( •* a... 

* ~ 

~ • * :J * a: 4 I-- * 0 + I 

1- • • 

+ • • 

2 - + * + 

I • 

0 I I I I I I I I 

1 1.5 2 I 

2.5 3 3.5 4 4.5 5 5.5 

URANIUM, IN PARTS PER MILLION 

Figure 8. Scatterplot of uranium and thorium from samples of the West Foreland (asterisks), Tyonek (pluses), and Beluga Formations (rectangles) in the Cook Inlet Basin area. 

Susitna Lowlands, based primarily on uranium and thorium 

content of the potential host rocks. 

In a study of the Tyonek 1 :250,000-scale quadrangle 

area, Manning and Hinderman (1982) found no geologic 

environments favorable for uranium; however, they 

included the Cook Inlet Basin in their category of "unevaluated environments." They listed two uranium occurrences 

in the Tyonek quadrangle. One of these is near Shirley 

Lake in the northwestern part of the quadrangle, about 

55 km north of the northwest comer of the present study 

area. At Shirley Lake the uranium is on and adjacent to 

joints or fractures in basaltic and andesitic tuff and breccia (Freeman, 1963) and most likely was precipitated 

from ground water. The second uranium occurrence is in 

the Tyonek Formation along the Kahiltna River, about 52 

km north of the northeast comer of the present study 

area; no geologic or geochemical information is available. 

A radioactive spring has been reported near Beluga Lake 

(Sainsbury, 1990). Neither the exact location of the spring 

nor its relation to the Tyonek Formation, which crops out 

northeast of the lake, is known to the authors. Sainsbury 

(1990) claimed that both the spring water and the spring 

sediments are high in uranium and that the spring water is 

high in radon. 

CONCLUSIONS 

1. Uranium potential for the Tertiary Kenai Group 

and the Paleocene and Eocene West Foreland Formation is 

low in the study area. 

2. Uranium potential is higher for the West Foreland 

Formation than for the overlying Kenai Group because the 

West Foreland contains more volcanic materials and more 

evidence of epigenesis. 

3. Volcanic materials in the Tertiary sedimentary 

rocks in the study area have altered to a zeolite and to smectite. 

4. A strong correlation between thorium and uranium 

(r=+0.81) in samples of Tertiary sedimentary rocks in the 

study area suggests that substantial amounts of uranium have 

not been mobilized in oxidizing ground water. 

5. Association of uranium with other rare earth ele.:. 

ments including ytterbium suggests that uranium is abundant 

in a placer constituent of the sandstone. 

6. Three principal clay mineral suites are present in 

Tertiary sedimentary rocks of the study area: kaolinite, 

which is related to coal beds; chlorite and illite, which are 

closely associated (r=+0.67) detrital clays common in all 

of the sediment source areas but more abundant in the 
CONTINENTAL SEDIMENTARY ROCKS, NORTIIWESTERN COOK INLET AREA B15 

Kenai-Chugach Ranges-derived sediments than in the 

Aleutian-Alaska Ranges-derived sediments; and smectite, 

which resulted from alteration of the volcanic materials 

derived from the Aleutian-Alaska Ranges. 

7. Copper, nickel, and chromium, which are more 

abundant in mafic rocks and which are present in sulfide 

minerals, are associated with the illite-chlorite clays of the 

study area The clays suggest a relation to the KenaiChugach Ranges source, which is probably more mafic than 

the Aleutian-Alaska Ranges source. 

8. Titanium and iron are closely associated (r=+0.66) 

and probably are present together in the mineral ilmenite. 

Ilmenite represents a more felsic source, probably the Aleutian-Alaska Ranges. Titanium and iron are also associated 

with smectite, which is an alteration product of the volcanic 

materials more common in the Aleutian-Alaska Ranges 

source. 

9. The cations of calcium, manganese, and magnesium are associated with and probably represent the plagioclase and chlorite from mafic igneous rocks and 

metamorphic rocks of the Chugach-Kenai Ranges sediment 

source area. 

REFERENCES CITED 

Adkison, W.L., Kelley, J.S., and Newman, K.R., 1975, Lithology 

and palynology of the Beluga and Sterling Formations exposed 

near Homer, Kenai Peninsula, Alaska: U.S. Geological Survey 

Open-File Report 75-383, 239 p. 

Adkison, W.L., and Newman, K.R., 1973, Lithologic characteristics and palynology of Upper Cretaceous and Tertiary rocks in 

the Deep Creek Unit well, Kenai Peninsula, Alaska: U.S. Geological Survey Open-File Report, 271 p. 

Barnes, F.F., 1966, Geology and coal resources of the Beluga-Yentna region, Alaska: U.S. Geological Survey Bulletin 1202-C, 

54p. 

Barnes, F.F., and Cobb, E.H., 1959, Geology and coal resources of 

the Homer district, Kenai coal field, Alaska: U.S. Geological 

Survey Bulletin 1058-F, p. 217-260. 

Beikman, H.M., 1980, Geologic map of Alaska: U.S. Geological 

Survey, scale 1:2,500,000. 

Biddle, K.T., 1977, Preliminary study of heavy minerals from the 

Beluga and Sterling Formations exposed near Homer, Kenai 

Peninsula, Alaska: U.S. Geological Survey Open-File Report 

77-874, 12 p. 

Calderwood, K.W., and Fackler, W.C., 1966, Significant oil and 

gas developments in Alaska, 1965-1966 [abs.]: American 

Association of Petroleum Geologists Bulletin, v. 50, no. 9, 

p. 2029-2030. 

--1972, Proposed stratigraphic nomenclature for Kenai 

Group, Cook Inlet Basin, Alaska: American Association of 

Petroleum Geologists Bulletin, v. 56, no. 4, p. 739-754. 

Crick, R.W., 1971, Potential petroleum reserves, Cook Inlet, Alaska: American Association of Petroleum Geologists Memoir 

15,v. 1,p. 109-119. 

Croff, C., Lessman, J., Bigelow, C., and Ruzicka, J., 1977, Uranium 

favorability of the Cook Inlet Basin, Alaska: Prepared by 

WGM Inc., Anchorage, Alaska, for the U.S. Deparbnent of 

Energy, Grand Junction Office, v. 1, 163 p., v. 2, 138 p., v. 3, 

56 maps. 

Dall, W.H., and Harris, G.D., 1892, Correlation papers, Neogene: 

U.S. Geological Survey Bulletin 84, p 234-236. 

Davis, J.C., 1986, Statistics and data analysis in geology (2nd ed.): 

New York, Wiley, 646 p. 

Dickinson, K.A., and Campbell, J.A., 1978, Epigenetic mineralization and areas favorable for uranium exploration in Tertiary 

continental sedimentary rock in south-central Alaska, a preliminary report: U.S. Geological Survey Open-File Report 

78-757, 14 p. 

Dickinson, K.A., and Skipp, G.L., 1992, Clay mineral depositional 

facies and uranium resource potential in part of the Tertiary 

Kenai Group, Kenai Peninsula, Alaska: U.S. Geological Survey Bulletin 1999, p. 81-99. 

Eakins, G.R., 1969, Uranium in Alaska: Division of Mines and 

Geology, Department of Natural Resources, State of Alaska, 

Report 38, 49 p. 

Freeman, V.L., 1963, Examination of uranium prospects, 

1956-Shirley Lake, in Contributions to economic geology of 

Alaska: U.S. Geological Survey Bulletin 1155, p. 29-30. 

Harmon, H.H., 1960, Modem factor analysis (2nd rev. ed.): Chicago, University of Chicago Press, 471 p. 

Hayes, J.B., Harms, J.C., and Wilson, T., Jr., 1976, Contrasts 

between braided and meandering stream deposits, Beluga and 

Sterling Formations (Tertiary), Cook Inlet, Alaska, in Miller, 

T.P., ed., Recent and ancient sedimentary environments of 

Alaska: Alaska Geological Society Symposium, Proceedings, 

p. Jl-J26. 

Hintze, J.L., 1992, Number cruncher statistical system, version 5.3, 

reference manual: Kaysville, Utah, J.L. Hintze, 424 p. 

Hite, D.M., 1976, Some sedimentary aspects of the Kenai Group, 

Cook Inlet, Alaska, in Miller, T.P., ed., Recent and ancient sedimentary environments in Alaska: Alaska Geological Society 

Symposium, Proceedings, p. I1-122. 

Kirschner, C.E., and Lyon, C.A., 1973, Stratigraphic and tectonic 

development of Cook Inlet Petroleum Province, in Pitcher, 

M.G., ed., Arctic geology: American Association of Petroleum 

Geologists Memoir 19, p. 396-407. 

Koch, G.S., Jr., and Link, R.F., 1971, Statistical analysis of geological data, volume 2: New York, Dover, 417 p. 

Kremer, M.C., and Stadnicky, George, 1985, Tertiary stratigraphy 

of the Kenai Peninsula-Cook Inlet region, in Sisson, Alexandra, ed., Guide to the geology of the Kenai Peninsula: Anchorage, Alaska Geological Society, p. 24-42. 

Magoon, L.B., Adkison, W.L., and Egbert, R.M., 1976, Map showing geology, wildcat wells, Tertiary plant fossil localities, K-Ar 

age dates, and petroleum operations, Cook Inlet area, Alaska: 

U.S. Geological Survey Miscellaneous Investigations Series 

Map I-1019, scale 1:250,000, 3 sheets. 

Magoon, L.B., and Egbert, R.M., 1986, Framework geology and 

sandstone composition, in Magoon, L.B., ed., Geologic studies 

of the lower Cook Inlet COST No. 1 well, Alaska outer continental shelf: U.S. Geological Survey Bulletin 1596, p. 65-90. 

Manning, K.H., and Hinderman, T.K., 1982, National uranium 

resource evaluation-Tyonek quadrangle, Alaska: U.S. 

Department of Energy Open-File Report PGJ 059(82) 18 p. 
B16 URANIUM FAVORABIUTY OF TERTIARY ROCKS, SOU1H-CENTRAL ALASKA 

Millard, D.J., Jr., 1976, Determinations of uranium and thorium in 

USGS standard rocks by the delayed neutron technique: U.S. 

Geological Survey Professional Paper 840, p. 61-65. 

Myers, A.T., Havens, R.G., and Dunton, P.J., 1961, A spetrochemical method for the analysis of rocks, minerals and ores: U.S. 

Geological Survey Bulletin 1084-1, p. 1207-1229. 

Odum, J.K., Yehle, L.A., Schmoll, H.R., Gardner, C.A., Dearborn, 

L.L., 1988, Lithological, geotechnical properties analysis, and 

geophysical log interpretation of U.S. Geological Survey drill 

holes 1C-79, 2C-80, CW 81-2, and CE 82-1, Tyonek Formation, UpperCooklnletregion, Alaska: U.S. Geological Survey 

Bulletin 1835, 27 p. 

Parkinson, L.J., 1962, One field, one giant-The story of 

Swanson River: Oil and Gas Journal, v. 60, no. 13, 

p. 180-183. 

Sainsbury, C.L., 1990, Rocks and wings: Denver, C.L. Sainsbury, 

273p. 

Wolfe, J.A., Hopkins, D.M., and Leopold, E.R., 1966, Tertiary 

stratigraphy and paleobotany of the Cook Inlet region, 

Alaska: U.S. Geological Survey Professional Paper 398-A, 

32p. 

Wolfe, J.A., and Tanai, Toshimasa, 1980, The Miocene Seldovia 

Point flora from the Kenai Group, Alaska: U.S. Geological 

Survey Professional Paper 1105, 52 p. 
CONTINENTAL SEDIMENTARY ROCKS, NORTHWESTERN COOK INLET AREA B17 

APPENDIX I-CHEMICAL AND 1\1INERALOGICAL DATA FOR 

SAMPLES OF THE WEST FORELAND, T,VONEK, AND BELUGA FORMATIONS 

Samples are shown by number in measured sections of appendix 2. Elements are in parts per million (ppm) or percent, 

as indicated at top of column. Values for quartz, feldspar, chloritle, illite, smectite, and zeolite are peak areas in square inches; 

the crystallographic indices of the peaks measured are given in table I. Mean is the arithmetic mean; St. dev. is standard 

deviation. 

A. Description of samples 

Sample ~easured 

number section 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

25 

26 

27 

28 

19 

17 

17 

18 

18 

21 

20 

20 

10 

11 

14 

13 

13 

13 

16 

15 

9 

12 

2 

3 

8 

8 

6 

6 

4 

7 

5 

1 

Rock type 

BELUGA FORMATION 

Mudstone, gray to brown, calcareous, conglomeratic 

Siltstone, gray, dense, calcareous 

Siltstone, gray, platy, calcareous, carbonaceous 

Siltstone, light-brown, dense, micaceous 

Sandstone, light-brown, fine- to medium-grained, unconsolidated 

Conglomerate, light-brown, silty, soft 

Sandstone, fine-grained, gray, silty, friable 

Sandstone, reddish-brown, medium-grained, poorly sorted 

TYONEK FORMATION 

Siltstone, brown to gray,. dense 

Siltstone, brown to gray, micaceous, iron-oxide-stained 

Sandstone, gray, soft, conglomeratic, noncalcareous 

Conglomerate, soft, sandy, silty 

Sandstone, tan, fine-grained, silty 

Claystone, brown-gray to gray, carbonaceous 

Siltstone, light-brown, micaceous, clayey 

Siltstone, brown, dense, micaceous, noncalcareous 

Siltstone, brown, dense, micaceous, noncalcareous 

Siltstone, tan, crumbly, trace carbon 

WEST FORELAND FORMATION 

Conglomerate, brown, soft, sandy 

Conglomerate, brown, hard, lithic 

Conglomerate, brown, hard, clayey, noncalcareous, volcanic grains 

Siltstone, brown, dense, noncalcareous 

Sandstone, light-brown, coarse-grained, noncalcareous 

Claystone, light-gray, brown, crumbly 

Siltstone, tan, dense, trace iron oxide stain 

Conglomerate, brown, soft, sandy, silty 

Sandstone, brown, fine- to coarse-grained, hard, tuffaceous 

Conglomerate, brown, hard, calcareous 
to 

..... 

00 

B. Chemical and mineralogical data 

Sample u Th Fe Mg Ca Ti Mn Ba Cr Cu Ni Sc Sr v 

number (EEm2 (,E,Em) (.eercent) (.eercent2 (,Eercent) ~.eercent) (EEm) (EEm2 (,E,Effi) (,E,Effi) ~EEm2 (E,Em) (,E,Em) (,E,Em) 

BELUGA FORMATION 

1 2.1 3.3 3.0 1.5 2.0 0.50 700 700 50 50 30 15 300 150 c: 

~ 

2 3.1 5.4 3.0 1.5 0.30 0.50 700 700 150 70 70 20 200 150 

4 

3 

4.9 

2.4 

7.7 

2.7 

5.0 

2.0 

0.70 

1.0 

0.70 

7.0 

0.50 

0.30 

700 

300 

1,000 

500 

100 

70 

70 

50 

70 

30 

20 

15 

200 

200 

150 

70 ~ s:: 

5 2.1 3.7 1.5 0.70 0.70 0.30 300 700 30 15 20 7.0 150 70 "t1 

6 1.9 4.8 2.0 1.5 1.5 0.30 700 700 30 30 30 15 200 70 ~ 7 2.7 3.8 3.0 2.0 0.30 0.30 300 700 70 50 50 15 150 100 ~ 8 1.7 0.59 3.0 1.5 2.0 0.30 300 700 15 15 7.0 15 700 100 ~ Mean 2.62 4.00 2.81 1.30 1.81 0.38 500 713 64.4 43.8 38.4 15.3. 263 80.0 - St. dev. 0.97 1.95 1.00 0.43 2.07 0.10 200 127 41.3 20.4 1.41 3.77 171 54.3 § TYONEK FORMATION 0 

9 4.9 8.1 3.0 1.0 0.30 0.30 300 1000 100 70 50 15 150 150 "t1 

10 2.5 2.3 3.0 1.5 7.0 0.30 3,000 500 70 70 30 15 150 100 ~ 11 1.9 2.9 0.70 0.30 0.15 0.15 70 700 20 15 15 5.0 70 30 ~ 

12 2.1 0 0.50 0.15 0.15 0.07 70 1,000 15 30 7.0 3.0 50 30 

13 1.4 2.1 0.70 0.20 0.20 0.15 70 700 150 10 15 3.0 70 30 ~ to( 

14 5.1 6.2 1.0 0.50 0.30 0.30 30 700 100 70 15 15 150 150 ~ 

15 3.0 6.3 3.0 1.5 0.50 0.50 300 700 70 70 70 20 15 150 R 

16 4.6 4.0 5.0 1.5 0.70 0.30 700 1,000 100 70 70 15 15 150 ~ 17 5.0 11.9 3.0 1.5 0.30 0.50 150 1,000 100 70 70 20 20 150 w 

18 4.1 9.4 5.0 0.70 0.30 0.30 700 700 70 30 15 15 200 100 ~ 

Mean 3.45 5.32 2.49 0.89 0.99 0.29 539 800 79.5 50.5 30.7 12.6 89.0 104 c: 

s St. dev. 1.35 3.52 1.62 0.55 2.01 0.13 854 173 38.2 24.5 26.7 6.17 64.4 52.0 h WEST FORELAND FORMATION m 

20 

19 

3.7 

2.5 4.5 

7.6 

1.5 

1.5 

0.50 

0.50 0.70 

0.50 0.15 

0.20 

300 

300 

700 

700 15 

15 10 

15 

10 

7.0 10 

7.0 

200 

150 30 

30 ~ F= 21 3.2 5.6 3.0 0.70 1.5 0.30 300 1,000 30 70 15 7.0 300 70 

22 2.0 2.1 5.0 1.5 3.0 0.50 500 1,000 15 15 5.0 20 700 70 

23 3.6 5.3 1.0 0.15 0.50 0.15 150 1000 7.0 7.0 3.5 10 150 30 til 

~ 24 4.3 9.7 3.0 0.70 0.70 0.30 150 700 30 15 15 15 100 70 ~ 25 4.9 7.9 2.0 0.70 0.30 0.30 200 1,000 70 30 20 15 150 70 

26 3.4 4.0 3.0 1.0 2.0 0.50 700 700 15 15 7.0 20 300 70 

27 2.2 4.2 1.5 0.50 0.70 0.30 150 700 15 15 15 7.0 200 30 

28 2.4 2.7 1.5 3.0 3.0 0.07 700 500 15 15 15 5.0 70 30 

Mean 3.23 5.36 2.30 0.93 1.29 0.28 345 800 22.7 20.7 11.3 11.6 232 44.0 

St. dev. 0.89 2.28 1.14 0.77 0.98 0.14 204 173 17.2 17.4 5.19 5.26 172 28.0 
Sample 

number 

1 

2 

3 

4 

5 

6 

7 

8 

Mean 

St. dev. 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

Mean 

St. dev. 

19 

20 

21 

22 

23 

24 

25 

26 

27 

28 

Mean 

St. dev. 

Y 'h: AI Na K Ga Yt Quartz Feldspar Chlorite Illite Smectite 

(ppm) _ ___{Qpm) _ _fu~cent) -~rcent) _ ___fuercent} ____ (ppm) (ppm) (in.

2

) (in.

2

) (in. 

2) (in. 

2

) (in. 

2

) 

15 

30 

15 

30 

7.0 

20 

15 

15 

18.4 

7.48 

30 

20 

7.0 

7.0 

7.0 

10 

30 

30 

30 

30 

20.1 

10.5 

15 

30 

20 

30 

20 

30 

30 

30 

15 

15 

23.5 

6.73 

100 

100 

70 

100 

70 

100 

100 

70 

88.8 

14.5 

100 

70 

70 

30 

70 

70 

15 

10 

150 

100 

68.5 

40.5 

150 

150 

150 

100 

150 

150 

150 

150 

150 

70 

137 

26.9 

10 

7.0 

7.0 

13 

7.0 

7.0 

7.0 

10 

8.44 

1.99 

7.0 

7.0 

3.0 

1.5 

3.0 

7.0 

10 

10 

13 

13 

.7.35 

3.74 

7.0 

7.0 

7.0 

10 

7.0 

10 

13 

10 

3.0 

3.0 

7.65 

2.92 

3.0 

3.0 

3.0 

2.0 

1.0 

2.0 

1.5 

0.30 

1.98 

0.94 

0.70 

1.5 

0.50 

0.30 

0.70 

0.30 

2.0 

1.0 

0.70 

1.0 

0.87 

0.51 

1.5 

2.0 

3.0 

2.0 

3.0 

1.5 

3.0 

3.0 

0.70 

0.70 

2.04 

0.89 

1.5 

2.0 

2.0 

3.0 

1.5 

1.5 

1.5 

3.0 

2.00 

0.61 

.0 

1.5 

0.70 

0.70 

1.5 

3.0 

2.0 

3.0 

3.0 

3.0 

2.14 

0.93 

2.0 

3.0 

3.0 

1.0 

3.0 

2.0 

3.0 

3.0 

1.5 

1.0 

2.25 

0.81 

BELUGA FORMATION 

15 

15 

15 

20 

10 

10 

15 

15 

14.4 

3.00 

1.5 0.33 

1.5 0.36 

1.5 0.20 

3.0 0.17 

1.5 0.46 

1.5 0.50 

1.5 0.38 

1.5 0.16 

1.69 0.32 

0.50 0.12 

TYONEK FORMATION 

20 

15 

7.0 

5.0 

7.0 

30 

15 

15 

20 

20 

12.4 

6.79 

2.0 0.32 

1.5 0.17 

1.0 0.60 

0.70 0.24 

0.70 0.59 

1.5 0.25 

2.0 0.25 

2.0 0.29 

3.0 0.36 

3.0 0.29 

1.74 0.34 

0.79 0.14 

WEST FORELAND FORMATION 

15 1.5 0.58 

15 3.0 0.24 

15 2.0 0 

15 3.0 0 

15 3.0 0.30 

20 3.0 0.16 

30 3.0 0.23 

15 3.0 0.10 

15 1.5 0.48 

7.0 1.5 0.50 

16.2 2.45 0.26 

5.47 0.69 0.20 

0.12 

0.10 

0.06 

0.05 

0.09 

0.06 

0.07 

0.24 

0.10 

0.06 

0.06 

0.06 

0.03 

0.09 

0.04 

0.0 

0.09 

0.04 

0.03 

0.02 

0.05 

0.03 

0.10 

0.11 

0.23 

0.02 

0.30 

0.25 

0.07 

0.21 

0.05 

0.05 

0.14 

0.09 

0.05 

0.10 

0.07 

0.09 

0.02 

0.04 

0.14 

0 

0.06 

0.04 

0.10 

0.11 

0.04 

0.17 

0.04 

0.11 

0.09 

0.10 

0.13 

0.06 

0.10 

0.04 

0.01 

0 

0.02 

0 

0 

0 

0.11 

0.01 

0.01 

0.03 

0.02 

0.03 

0.05 

0.07 

0.02 

0.04 

0.02 

0.02 

0.05 

0 

0.03 

0.02 

0.07 

0.03 

0.01 

0.03 

0.02 

0.04 

0.02 

0.05 

0.05 

0.01 

0.03 

0.02 

0.03 

0 

0 

0 

0 

0 

0 

0 

0 

0.02 

0.01 

0.01 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0.81 

0 

0.46 

0 

0 

0.11 

0 

0.14 

0.26 

Zeolite 

(in. 

2

) 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0.05 

0.23 

0.12 

0.03 

0 

0 

0.05 

0.10 

0 

0.06 

0.07 

(") 

i 

~ Vl 

m 

~ m 

~ ~ 

.-< 

~ 

R 

~ 

i 

~ ~ 

z 

§ 

~ 

~ 

~ 

~ 

\0 -
B20 URANIUM FAVORABIUTY OF TERTIARY ROCKS, SOUTII-CEN1RAL ALASKA 

APPENDIX 2-MEASURED SECTIONS OF THE WEST FORELAND, TYONEK, 

AND BELUGA FORMATIONS 

Locations of sections are shown in figure. 2. Section scales are in meters; sample numbers are circled and in bold, alongside scale. 

Section 1. West Foreland Formation. Theodore River. NWif4sec. 22, T. 15 N., R. 10 W., Seward Meridian 

_ o~o ?~o ~<Qo'o.~o q~o.'o ~OQ·d~ . . . ... . . . . . . . '0_,0

o.:odo ~ .o ~ oO~ ·o~o ·o .~~p"oo 

Conglomerate, brown, hard, sandy; poorly exposed 

Sandstone, brown, fine-grained, hard, dense; coarse and gritty near top; interbedded conglomerate, brown, 

hard, rounded pebbles, poorly exposed, maximum grain size 3 em 

Conglomerate, brown, hard, sandy; poorly exposed 

Sandstone, brown, hard, medium-grained, lenticular; poorly exposed 

Sandstone, brown, fairly hard; poorly exposed; conglomerate beds at various intervals 

Conglomerate, grayish-brown, thick-bedded; well-rounded grains as much as 6 em in diameter; some beds 

hard 
CONTINENTAL SEDIMENTARY ~OCKS, NORTIIWESTERN COOK INLET AREA 

Section 2. West Foreland Formation. East bank of the Theodore River. SE1/4 sec. 23, T. 15 N., R. 10 W., Seward Meridian 

5o-= o-- 0 _- _ 0 0 0 0 

-O=o-=-o-=._o 

·cj:Pocfb. · · ... ·~ fJl). .·~ 

·

0 oo ... <?o .. . ~ 0 ·0 . 0 C3:J> .. oo o 40 - 0 0 0 0 0 . 0 

@ 0 o·O o 0 o 0 - oooo 0.00 oooooo 

oo o o o 0 00 oo 09 .. o,P .. O 

30 

·.·."i;~~4··:·: . o o. ·o· o... . .o. 

.··H···~···.· 20-· :~·: · ....... : .· 

10-

0 

·.. . . . .. . 

- o- o- o- - 0-()_9-_ 

- o- - o o-o~o- o 

0 - o- o - o- o-=. _Q 

-_ o--=-- o-_o _2 

-o-O-o0-

_9 0 - 0-

o--

0 

Sandstone, light-brown, friable, covered 

Conglomerate claystone, bluish-gray; rounded pebbles 1-5 em in diameter suspended in matrix; top 1.0 m 

dark-gray mudstone 

Conglomerate, orang ish-red; horizontal beds 0.5-1.0 m thick; abundant rounded pebbles 2-5 em in diameter; 

grain-supported medium- to coarse·-grained sand matrix; foreset and tabular-planar crossbeds; coal clasts; 

channel deposits and sand lenses 1.0-2.0 m thick; crossbeds typical of longitudinal bars 

Sandstone, brown, fine-grained; silty, light-gray claystone interbeds 1.0-2.0 em thick 

Conglomerate, yellowish-brown; granules to pebbles; coarse-grained sand matrix 

Sandstone, reddish-brown, fine-grained; silty clay lenses 

Conglomerate, yellowish-brown; granules and pebbles; grain-supported medium-grained sand matrix; coal 

clasts in channels 

Sandstone, light-brown, fine-grained, friable; thickens laterally; pebble conglomerate lenses 0.5 em thick 

Claystone, conglomeratic, dark-gray, massive; pebbles and cobbles 2-10 em in diameter suspended in 

matrix; pebbles 1-3 em in diameter at top; locally oxidized to deep orange red; local zones of grain 

support 

Claystone, dark-bluish-gray; dark and light horizontal laminations 2-4 em thick (organic rich); scattered 

granules and pebbles as large as 5 em; few reddish-brown streaks 

Conglomerate, yellowish-brown, moderately well rounded; grain supported; oxidized, granules, pebbles, 

and cobbles 2.0 mm-10 em in diameter; tabular planar crossbeds 1.0 m thick 

Section 3. West Foreland Formation. West bank of the Theodore River 15.5 km upstream from its mouth. 

SW1

/4 sec. 36, T. 15 N., R. 10 W., Seward Meridian 

20-+~--~~~--~ 

10 

..... 

0 0 0 0 

0 0 0 0 . 0 0 0 

o 0 o 0

0 · o 8 

0 . 

0 o o o 0 

0 0 . oo. o o. oo 

0 0 ° 0 0 0 

0 . 0 0 o. 0 0 0 o. o 0 o 0 o 

.?? oooo .oo o 

Conglomerate, same as below; cliff-forming; top 1.0 m is dark-brown, medium to coarse-grained sandstone 

Conglomerate, reddish-brown, granular, crumbly; partly covered 

Sandstone, dark-brown, medium- to coarse-grained, poorly bedded 

Conglomerate, light-gray; well-rounded pebbles in 1.0 by 10.0 m channels 

Sandstone, dark-brown, medium-grained, poorly bedded; conglomeratic lenses, channels, and pebbles 

Conglomerate, medium-gray; pebbles and cobbles 2-8 em in diameter; grain-supported sand matrix 

Sandstone, dark-gray, coarse-grained, poorly bedded; rounded pebbles; lenses 20-30 em thick; channels 

2-3m long 

B21 
B22 

10 

URANIUM FAVORABILTIY OF TERTIARY ROCKS, SOU1H-CENTRAL ALASKA 

Section 4. West Foreland Formation.· On Bishop Creek 9.0 km southwest of Bishop Lake. SW1/4 sec. 22, T. 14 N., 

R. 13 W., Seward Meridian 

. ·. . . ·a· ? o. . 0. a ·O : 0. ·. 0 .... 0 · 0 b ·· ... ·~ o .a· :. . . . . 

· · . a··. · .. :a::. 

~ ·l~~~.*~~ ... ~l· . ·9 .. . · ... · .. ·a:'?· . . · 

Conglomerate, yellowish-brown (oxidized), well-rounded pebbles 1-3 em in diameter; coarse-grained 

sandstone matrix; mostly covered 

Sandstone, oxidized yellowish- to orang ish-brown, medium- to coarse-grained 

Conglomerate, yellowish-red; rounded pebbles 1-3 em in diameter; coarse-grained to very coarse grained 

matrix; oxidized sand lenses 

Sandstone, reddish-brown (oxidized), coarse-grained; pebbles; channels containing horizontal laminations 

of pebbles and granules 

®o-=--==-= Claystone, light-brown, poorly bedded, locally silty, crumbly; abundant oxidized yellowish-orange to 

reddish-brown streaks; mostly covered 

Section 5. West Foreland Formation. 1.5 km north of Lone Ridge and 6.4 km south of Bishop Lake. SE1/4 sec. 32, T. 14 N., 

R. 12 W., Seward Meridian 

Soil 

-. ·a· o· ... 

·. q:: : 6.··. ·g· rQ9.b·g· . . (}DO . 0 ·· ·Ob·.: . :. · · o· ·a". ·:a· <:Y 

30- ·~··8~~:6~~.~: 

:±<~ a·. ·a : .. · ... · .. : :.·a . 

Conglomerate, light-gray to brown; vague horizontal bedding; fine-grained sandstone matrix, variable grain 

to matrix support; pebbles generally-5 em in diameter; maximum clast size 10.0 em 

Sandstone to conglomerate, reddish- to yellowish-brown, tuffaceous, oxidized; granule-sized clasts; thin clay 

lenses and coaly layers 

Conglomerate, light-brown; vague horizontal bedding; mostly covered; well-rounded pebbles 2-3 em in 

diameter 

Sandstone and interbedded conglomerate, light-brown; medium-grained sand in lenses; pebble 

conglomerate 0.5 m thick in middle 

Conglomerate, light-reddish-brown, oxidized; pebbles 1-3 em in diameter; matrix supported; massive 

horizontal layers 

Sandstone, light-tan, medium-grained, hard; reddish-orange streaks 

10 - .·~~C?(?q~9c§8. Conglomerate, light-gray to dark-brown; fine- to medium-grained grain-supported sand matrix 

Sandstone, light-tan, medium-grained, hard, lenticular 

.

0 ·~o : 0 ·9 6: ·a O()C? · Conglomerate, dark-reddish-brown; medium-grained sand matrix, pebbles 2-5 em in diameter o.o · o· .. o :a. o 

0 

.o.Qo·o· o :o :0 ·.0 

o"· ·a:. .c:i"-o"o· 9: o .. b ·o·o 6· "<;). o·o .. . 9. ·~··?oq·b:<?:? (?· 

Sandstone, light-gray, medium- to coarse-grained, thick-bedded; reddish-brown streaks 

Conglomerate, dark-reddish-brown, horizontally bedded; medium-grained sand matrix; oxidized pebbles 

1-3 em in diameter 
CONTINENTAL SEDIMENTARY ROCKS, NORTIIWESTERN COOK INLET AREA 

Section 6. West Foreland Formation. 5.4 km north of Lone Ridge. Section 30, T. 14 N., R. 12 W., Seward Meridian 

-------

-------

· ... ·~··. 

... -:---:--

20 - =_:____, =__:_-=-~ =· 

(.)A\ _f=-_~ -=-_i=-_-=--~---=­ 'e' ------

~-=-=-=-=-= -:.~· .··:-.-:· .. · ...... ---r---:-· ··~· 

· .. ·.· 

-~~··>.·.· .. ·: ... @-:·· .. ·.··:·· 

Covered 

o~------------~ 

Clay, gray, crumbly, soft; interbedded with 0.5-cm-thick layers of carbonized wood 

Sandstone, light-brown, fine-grained, soft, clayey 

Clay, light-brown, soft; interbedded black carbonaceous clay and light-brown sandstone 

Sandstone, light-brown, soft, clayey, micaceous 

Clay, light-brown, crumbly 

Sandstone, light-brown, fine-grained, clayey 

Sandstone, light-brown, fine- to medium-grained 

Sandstone, light-brown, medium- to coarse-grained; conglomerate beds and lenses as thick as 30 em 

Section 7. Lower part of the West Foreland Formation. South side of Capps Glacier. NW1/4 sec. 22, T. 14 N., R. 15 W., 

Seward Meridian 

@ 

80 

o. 0 0 0 ~ 0 ~ 

o· 0· 0 0 

0 0 0 0 

0 0 

0 0 0 

0 ·0 

0 

0 0 0 

: . . : .. ·.··.· ... /.. 

0.0 0 0·0 

·0·0-000 

0 0 . o _o o. 

0 0 0 

o. o ·o. o_ 

0 0 0 0 

. 0· 0 . 0. 0 

0 . 0 0 

Conglomerate, yellow to brown and yellowish-orange; oxidized zones; coarse-grained to very coarse 

grained sand matrix; rounded pebbles, cobbles, and boulders 1-40 em in diameter 

Sandstone, brown to grayish-brown, medium-grained to very coarse grained, crumbly, friable, massive; 

poor horizontal bedding; light-brown to green, very fine grained sandstone and claystone lens, 0.5-40. 

em thick 

Claystone, dark-reddish-brown, silty, very poorly bedded, sparsely carbonaceous 

Sandstone, green to buff, very fine grained, poorly bedded, well-cemented, noncalcareous, shaly; horizontal 

layers of wood fragments, green patches, and layers of clay clasts 

Conglomerate, light-brown, medium-grained to very coarse grained; sand matrix, massive horizontal beds 

4 m thick; conglomeratic sandstone lenses 0.5 m thick by about 15 m wide 

B23 
B24 

40 

30 

20 

10 

0 

URANIUM FAVORABILITY OF TERTIARY ROCKS, SOU1H-CENTRAL ALASKA 

Section 7 (continued) 

. ·. ·. ·.· .. ~ : 

. · .. ." ~ · ........ o .. 

... . . 

. : · .. ·.~ .... · .·.: . ·.o·· . 

•. · .. 

:~·. >: . ·.: .. .. ·~···· ·. · .. ·.o· 

·~.··.·.c>.·.··.· 

·.··.·. ·.·:. . . 

Sandstone, dark-brown, medium-grained; mostly covered; horizontally massive horizontal bedding; 

conglomeratic zones with rounded pebbles 1-5 em in diameter; more conglomeratic upward 

Conglomerate, dark- to yellowish-brown, horizontally bedded; sandy matrix; pebbles 1-4 em in diameter 

Sandstone, yellow to brown, coarse-grained, conglomeratic, thick-bedded; partly covered; scattered, 

rounded, green to gray volcanic pebble~; medium-grained sandstone lenses in bottom 1 m; yellow to 

brown, medium-grained sandstone near top 

Sandstone, light-green to gray, clayey; fines upward to siltstone and silty claystone 

Conglomerate, yellow to brown, sandy; rounded, scattered pebbles 

Conglomerate, light-brown to gray; abundant rounded pebbles 3-5 em in diameter; maximum particle size 

15 em; top layer of yellow to brown, oxidized sandstone 
CONTINENTAL SEDIMENTARY ROCKS, NORTIIWESTERN COOK INLET AREA 

Section 8. Upper part of the West Foreland Formation. 12.5 km west of toe of Capps Glacier. NW1/4 sec. 22, T. 14 N., 

R. 15 W., Seward Meridian 

o~~o~6 ~~~o·%Oo~: 

- :~-~~0-~6 _c1:J ·~:_~-~ ~ .. ~ 

@ -----,..~-,-----,-~--,---~-----:-~......--! 

140- .. 

. ?··.· .. ·.··.··c?.: ~.·.···a . . . o.. . . . 

-:0 t .. \ 

130-

00

.·~··.·.···· o 

.q: ._"-:· ¢· .. · .... ·_o" .: : .. . : . 0 ... 

- ·.: . . : : : ··~ · ... · 

:_q.··.·~·o:·.·.·.· ·.· .. ·s· .. ·. . 0 . . 0 · . 

120 - · ·? : .·· .· . ·. ·o·.: .. : · . ·o· .... 

. ·.·. 6 ··:·_·?· .... · b:: - . SJ"". .o. 

· ...... ~_ ..... --~· .. ·· :6·: .. 0 : : . p .... 

· ..... o.· .· 110 - . ·. c: . ·. . . 0 .. 

. p··.· .. · .. 

. : · .. ·. ~ ~- ~6· . . . o· ·. . · .. o:·. 

100- ... : ............ ·· ~~~~~~ 

·.·.·.·. · ... ·.· ··.· .·: 

~~~~ ............... 

~~~~~~ 

-o." .Q. · . · _.o·. Oo .· .. '? 

90- ~o: ~-:o}jo" . 0. 

_:?.-o: o .. o. · . · o ·c( ~ . o." 

: 0:9 .... c:.·~·. -~.· .. o ... 0 ·. 

20 _ .• 

0 

.~··.:·· 6· .... · .. ... · .. t ....:...._· z 

·o :"Q:· ··o" .. ·· o_:·_. 

-:.·_.¢: .. o:· ·.6 o o . ." 

_0_ · .. :c? ." :<;)· P:· 

: .··9.· .·.o: -~.: ·q:·: 

10-·:o ..... q ... . · 0 ·.a.: 

Q ":. -~_ ... 0·_·. Q. :·~. 

·.-o··>o ·. -o·.· o: 

-oa(oo/ 

Sandstone, light-grayish-brown, fine- to coarse-grained, soft, poorly sorted; a few thin conglomerate beds 

Mudstone, grayish-brown, crumbly, blocky; dark-gray coating on fractures 

Sandstone, grayish-brown, fairly soft, crumbly 

Conglomerate, gray to grayish-brown, very sandy, soft 

Mudstone, light-grayish-brown, brittle, sandy at intervals; conchoidal fracture with dark-gray coating on 

surfaces; scarce carbonized plant fragments 

Conglomerate, light- to medium-gray, sandy, soft, massive; maximum clast size 20 em; a few thin beds of 

grayish-brown hard sandstone containing volcanic pebbles, plant fragments, and interbedded gray 

mudstone 

B25 
B26 URANIUM FAVORABILITY OF TERTIARY ROCKS, SOUTII-CENTRAL ~ASKA. 

Section 9. West Foreland Formation. Along the Chuitna River 8.0 km northwest of its confluence with Chuit Creek. 

SE1

/4sec. 19, T. 13 N., R. 13 W., Seward Meridian 

Recent soil 

OOQOQOOooOoO 

oooooooooooo 

- .. · .· .·: .· .· .· .· .· .· .· .·.· .· ... · 000000000000 

co ooooooooo o 0 00 0 0 0 0 0 0 0 0 0 

~O.no~ 0~ On·O~ o, ~~O~o,"o~;n 0 

Conglomerate, light-brown, horizontally bedded; granules and pebbles, maximum clast size of 2 m; very 

coarse grained interbedded sandstone 

30 - J~.~~:~:· .. : =~ i ~L;/: .......... · ... Sandstone and conglomerate, light-brown; pebbles 1-2 em in diameter in bedding planes; troughs with low 

-angle foresets 

o· oooqooGc·, 

•. • pco~o: • • 0 O.o oo' • 

. o·o !~·o~·; ·• 0 , ·~ o• 

' :;.o 'ooo' •' ·. ·?~·o ~· . , 

Sandstone and conglomerate, light-brown; same as below but coarser; pebbles to cobbles 

Sandstone, light-brown, coarse-grained to very coarse grained, conglomeratic; some low-angle foresets; 

some pebble-bearing horizontal beds 

Sandstone, brown; interbedded with light-gray claystone 

Conglomerate and sandstone, reddish-brown (oxidized), coarse-grained to very coarse grained; scattered 

granules and cobbles and lenses with low-angle crossbeds 

Sandstone, grayish-brown, fine-grained; partly covered 

Conglomerate, brown; yellowish-brown oxidized zones; granules to pebbles; coarse sand matrix; a few coaly 

lenses; crossbeds; clay lenses 

Conglomerate and sandstone, light-brown, medium- to coarse-grained; low-angle foreset crossbeds and 

trough crossbeds 

Sandstone, medium- to coarse-grained, friable; scattered pebbles; partly covered 
CONTINENTAL SEDIMENTARY ROCKS, NORTIIWESTERN COOK INLET AREA 

Section 10. Tyonek Formation and Pleistocene glacial till. Along Coal Creek 5 km south of Coal Creek Lake. 

SE1/4 sec. 26, T. 16 N., R. 13 W., Seward Meridian 

Conglomerate, reddish-brown (Pleistocene glacial till) 

Coal, black, flaky, silty; light colored on weathered surfaces 

Mudstone, gray to brown, micaceous; a few beds of medium-gray to grayish-brown sandstone 

Section 11. Tyonek Formation and Pleistocene glacial till. Along Coal Creek 3 km north of Beluga Lake. 

SW1

/4 sec. 31, T. 16 N., R. 12 W., Seward Meridian 

Conglomerate, reddish-brown; Pleistocene glacial till; boulders as much as 1 m in diameter 

B27 

Sandstone, light-grayish-brown, medium- to coarse-grained; reddish-brown at base; varicolored grains; th 

irregular beds have oxidized tops and layers of carbonaceous particles; interbedded conglomerate at 

various horizons; coal fragments at top, rounded coal pebbles at base; some layers contain pebbles and 

cobbles as much as 10 em in diameter 

Coal, black, flaky 

Clay, gray, soft; oxidized reddish-brown at base; carbonaceous fragments 

Coal, black, flaky 

Mudstone, medium-gray; blocky fracture; brown on weathered surfaces; carbonized wood in thin layers at 

intervals; traces of mica; calcareous concretions 0.15 by 0.5 m 
B28 

80 

70 

60 

50 

URANIUM FAVORABILTIY OF TERTIARY ROCKS, SOUTII-CENTRAL ALASKA 

Section 12. Tyonek Formation on the south side,and·near the toe of Capps Glacier. SW1/4, sec. 10, T. 14 N., R. 14 W., 

Seward Meridian ·-

. : . ::: · .. : .. :-.. 

··-······- :-:-:"':"'.·.·.:..:.:..:;-:-;-;.:·.:..:..:.:;-:-;-;.:· .. : .. : .. :...: 

Claystone, gray; interbedded with shaly coal beds about 30.0-40.0 em thick 

Claystone, gray, sandy 

Coal, gray, shaly; 0.5-1.5 m thick 

Claystone, gray; partly covered 

Claystone, light-gray; thin coal beds about 1 m apart at top 

Shale, gray, interbedded with shaly coal; coal beds about 1 m thick separated by shale beds 1-2 m thick; 

uppermost coal bed contains less shale 

Sandstone, brown; deposited in channels cut into underlying beds; channel sandstone is generally massive 

and has slight horizontal color banding 

Siltstone and fine-grained sandstone, light-brown; siltstone and sandstone beds 1.0-1.5 m thick separated 

by shale beds 10-20 em thick that form small escarpments 

Coal, black, shaly 

Claystone, light- to dark-gray, crumbly, shaly; darker layers are coaly 

Claystone and crumbly shale, light-gray; grades upward to shaly coal beds 10-20 em thick separated by 

claystone beds 30-40 em thick 

Coal, black, shaly, crumbly, lenticular 

Claystone, light-gray; darker zones; partly covered 

Sandstone, light-gray, medium-grained; clayey upward 

Claystone, light- to bluish-gray, poorly bedded; mostly covered 

Coal, black, shaly, interbedded with claystone; pinches out 

Claystone, light-gray, crumbly; reddish-brown color bands; light and dark (carbonaceous) laminatrons 

Coal, black to grayish-brown, shaly; grades upward to clayey shale 

Sandstone, light-gray, medium-grained; interbedded with gray claystone at 

Sandstone, light-gray to brown, fine-grained; shaly and coaly at top 

Claystone, gray to brown, very poorly bedded, crumbly, shaly; coaly at top 
CONTINENTAL SEDIMENTARY ROCKS, NORTHWESTERN COOK INLET AREA 

Section 13. Lower part of the Tyonek Formation. On Capps Creek, 3 miles south of the toe of Capps Glacier. 

SW1/4 sec. 24, R. 14 W., T. 14 N., Seward Meridian 

. ·.· . 

Coal, black, hard; blocky fractures (Capps coal bed) 

Claystone, medium-brown and light-gray; yellowish-brown at top 

Sandstone, medium-gray, soft; faintly laminated near top 

Claystone, medium-gray, blocky; poorly exposed 

Coal, black, hard; blocky fracture 

Claystone, light-gray to grayish-brown, crumbly; interbedded with siltstone 

· -.. ·-. . . . Sandstone, light-gray to brown, fine-grained, clayey 

Sandstone, light-gray, fine- to medium-grained, faintly crossbedded 

@ -lr-----'---. ,__· . ...._· ."'-- . ...._·. ~ 

.· .. q·~:?·o.o· 

. ·c:· · .. ? :. : ~.: q. : 

· -~ .. ·.·?.· 6 · ·. ·.0 0 Sandstone, light-gray, conglomeratic; subtle planar bedding throughout; maximum clast size 23 em 

@ 

Conglomerate, light-gray, soft, very sandy; maximum clast size 6 em 

B29 
B30 URANIUM FAVORABIUIY OF TERTIARY ROCKS, SOU1H-CENTRAL ALASKA 

Section 14. Tyonek Formation. On Chuitna River, 5 km northwest of entrance of Chuit Creek. NW1

/4 sec. 28, 

T. 13 N., R. 13 W., Seward Meridian 

30-.------------~ Covered 

Mudstone and siltstone, grayish-brown 

~::r:zr::==:::r:z:::o:r::::j-Limestone, brown, hard; plant fossils 

Claystone, medium-gray, crumbly 

-=--=--=--=--=--=- ..--Siltstone, light-brown, thin-bedded, soft 

20 -Limestone, brown, hard; leaf fossils 

Claystone, medium-gray, crumbly; subject to landslides 

Claystone, medium-gray, sticky, crumbly; interbedded with light-brown siltstone 

Covered 

Coal 

Covered 

Sandstone, gray, soft, conglomeratic 
CONTINENTAL SEDIMENTARY ROCKS, NORTIIWESTERN COOK INLET AREA 

Section 15. Upper part of Tyonek Formation. Along Chuit Creek at its junction with Chuitna River. 

SW1/4 sec. 1, T. 12 N., R. 13 W., Seward Meridian 

Sandstone, light-brown to buff, medium-grained, well-sorted; crossbeds and iron-stained lenses 

Claystone, grayish-brown, crumbly; interbedded with fine-grained sandstone 

Sandstone, orange-red, fine-grained, well-sorted, very friable 

Claystone, dark-reddish-brown, carbonaceous, horizontally bedded 

Sandstone, light-brown, fine- to medium-grained; iron-stained zones; some clay matrix and clay lenses 

Coal and coaly shale, fibrous; woody texture 

Sandstone, reddish-brown, iron-stained, medium- to fine-grained; interbedded with bluish-gray shale 

Coal to coaly shale, limonite-hematite-stained 

Sandstone, light-gray, fine- to medium-grained; finer at top; partly covered; interbedded with a few bluish-

. gray claystone beds 10.0 em thick 

Sandstone, gray; scattered, rounded granules to pebbles, tabular-planar crossbeds 

Sandstone, gray, medium-grained; thin beds of coarse-grained to very coarse grained sand; crossbeds and 

pebbles in sand matrix at the top 

Sandstone, light-brown to buff; limonite-hematite stains along some contacts between beds; tabular 

crossbeds, curved laminations of coarse-grained to very coarse grained sand, coal seams, and lenses of 

iron-stained clay 

Coal, black, shaly, crumbly, friable, fibrous; weathers into ledges (Chuitna coal bed) 

B31 
B32 

@ 

URANIUM FAVORABILTIY OF TERTIARY ROCKS, SOU1H-CEN1RAL ALASKA 

Section 16. Upper part of the Tyonek Formation. Along the Chuitna River 18.0 km upstream from its mouth. 

NE1/4 sec. 8, T. 12 N., R. 12 W., Seward Meridian 

40~--------------~ 

Sandstone, light- to reddish-brown, very friable, well-sorted, medium-grained, crossbedded; well-developed 

horizontal planar beds 0.5-1.0 m thick with coal layers and rounded pebbles along contacts between beds; 

crossbeds have tangential bases 

Coal, black, very shaly, flaky; fibrous wood, wood fragments, and horizontal laminations 

Chuitna coal bed 

Claystone, light-greenish-gray, irregularly bedded; interbedded with sandstone lenses; shaly at top 

Sandstone, light-brown, fine- to medium-grained; reddish brown staining; a few clay layers 13 em 

thick Claystone, light-gray; beds 12 em thick; medium-grained sandstone lenses 

Sandstone, light- to reddish-brown, fine- to medium-grained; scattered pebbles at base, lenses of pebbles, 

and beds and lenses of clay 

Claystone, medium-gray, sandy; scattered igneous pebbles and some coal clasts 
CONTINENTAL SEDIMENTARY ROCKS, NORTHWESTERN COOK INLET AREA 

Section 17. Beluga Formation. On the south bank of the Beluga River 4.0 km southeast of Felt Lake. 

NW1/4 sec. 10, T. 13 N., R. 11 W., Seward Meridian 

Claystone, medium- to dark-gray, crumbly; partly covered 

Coal, shaly, crumbly; poorly exposed 

Claystone, medium- to dark-gray, poorly bedded, crumbly; partly covered 

Coal, black, shaly, very crumbly; partly covered 

Claystone, medium- to dark-gray, poorly bedded, crumbly; partly covered 

Siltstone, dark-gray, calcareous, platy, carbonaceous; horizontal laminations 

Claystone, medium- to bluish-gray, poorly bedded; partly covered 

Coal, very shaly; partly blocky and partly crumbly; few blocks thicker than 10 em but some as thick as 20 

em near top 

B33 
B34 

60 

50 

30 

20 

10 

URANIUM FAVORABILITY OF TERTIARY ROCKS, SOU1H-CENTRAL ALASKA 

Section 1 7 (continued) 

·o· ..... 

~· 

c:::::=:::::::: ..... 

. ·::·.·.~ 

.. ,.c:=. . : : .::.·. 

·.~·.·.· 

. . 

Sandstone, light-gray, friable, crumbly; medium gray on fresh surfaces; partly covered; scattered, rounded 

granules and pebbles; locally cemented with medium- to fine-grained calcite; good horizontal laminations 

about 1-3 em apart 

Coal; bottom 2 m shaly, top blocky; a few crumbly beds 

Sandstone, light-gray, medium grained; scattered pebbles and lenses 5-10 em thick of granule 

conglomerate and claystone that has red to brown oxidized laminations; weathers into mostly covered 

pinnacles 

Sandstone, light-gray, medium-grained; clay matrix; lenses of medium-grained sandstone; hard beds with 

brown rim 20 em 1.0 m thick; weathers into vertical spires of badlandlike topography 

0 ~~---·--·~·--·~·~·~· 
CONTINENTAL SEDIMENTARY ROCKS, NORTIIWESTERN COOK INLET AREA 

Section 18. Beluga Formation. On Beluga River 13.5 km northwest of Beluga. NE1/4 sec. 14, T. 13 N., R. 11 W., 

Seward Meridian 

90 -,--------,-------, 

Sandstone, gray and brown, medium- to coarse-grained, crossbedded; crossbed sets 15 em thick and faint 

large-scale crossbeds 

Conglomerate, gray and brown, soft, sandy; maximum grain size 3 em; clast upward to mudstone and 

sandstone 

Sandstone, light-gray, fine-grained, soft 

Mudstone, medium-gray, dense, soft, crumbly 

Sandstone, light-gray and brown, fine-grained, crossbedded; interbeds and clasts of reddish-brown clay 

Mudstone, medium-grayish-brown, laminated 

Sandstone, grayish-brown, fine-grained, soft 

Mudstone, medium-grayish-brown, laminated; grades upward to fine-grained sandstone 

Covered; reddish-brown cindery material from burning coal 

Coal; some woody fragments; partly covered 

Mudstone, medium-grayish-brown, soft, crumbly; laminated or thin bedded at intervals; grades to finegrained sandstone in places 

Sandstone, medium-grayish-brown, soft, fine-grained, clayey; grades upward to siltstone and mudstone 

Mudstone, medium-grayish-brown, silty, carbonaceous, faintly thin bedded to laminated; interbedded with 

soft fine-grained grayish-brown sandstone 

Coal, black, hard, flaky; wood 

B35 
B36 

· .. 

10 

. ·.· .... 

® 

URANIUM FAVORABILITY OF TERTIARY ROCKS, SOU1li-CENTRAL ALASKA 

Section 19. Beluga Formation on the north bank of the Beluga River at the confluence with Coffee Creek. 

SW1/4 sec. T. 13 N., 7, R. 10 W., Seward Meridian 

. .. 

Claystone, brown to yellowish-brown, sandy; coal clasts, scattered pebbles, and granules; grades upward to 

sandstone 

Claystone, dark-gray, conglomeratic, sandy; brown zones; vague horizontal bedding; granule filled channel 

Sandstone, light- to medium-brown, medium-grained, very friable, oxidized 

Conglomerate, light-gray to light-brown, laminated; pebbles 1-4 em in diameter; granules 0.5-0.7 em in 

diameter abundant; medium- to fine-grained matrix; beds 0.5-5.0 m thick; interbedded medium-grained 

sandstone lenses with pebble and granule laminations; clay galls and wood molds in clay and sandstone 

lenses; low-angle foresets; a few filled channels have low-angle foresets 

Section 20. Beluga Formation. Along the Chuitna River 13.0 km upstream from its mouth. 

NE1/4 sec. 22, T. 12 N., R. 11 W., Seward Meridian 

Sandstone, brown, oxidized, fairly well sorted, crossbedded; some pebbles and small-scale contorted beds 

Mudstone, light-brown; laminated with thin coal beds; poorly exposed 

Sandstone, light-brown to gray; carbonaceous fragments and clayey coal beds at various horizons 

Coal, black, flaky 

Mudstone, gray, laminated; thicker layers are oxidized brown on surface and drape over logs in coal below; 

grades upward to thin-bedded siltstone at top 

1-ioiioloi._ _____ -r---- Coal; fossil tree bark and partially carbonized wood 

Mudstone, grayish-brown, dense, fairly hard; carbonized and partly carbonized wood fragments; some dark (j) ---'----''-'-...:..._ __ ...:...__"'- brown streaks 

Sandstone, grayish-brown, coarse-grained, poorly sorted, thinly to irregularly bedded; oxidized horizons and 

varicolored grains 
CONTINENTAL SEDIMENTARY ROCKS, NORTIIWESTERN COOK INLET AREA 

Section 21. Beluga Formation. On the south bank of the Chuitna River 8.0 km upstream from its mouth. 

SW1/4 sec. 20, T. 12 N., R. 11 W., Seward Meridian 

B37 

50 --r--------, 

30 

Covered 

Conglomerate, gray to brown; grain-supported, sandy matrix is more sandy upward; pebbles to cobbles, 

maximum clast size 2.0 em 

Conglomerate, gray to brown, sandy; interbedded with thin sandstone layers 

Conglomerate, gray to brown, sandy; granules to pebbles, maximum clast size 1-3 em; interbedded with 

medium-grained sandstone beds 10 em thick; scattered igneous clasts as large as 10 em 

Conglomerate, gray to brown, sandy; granules to pebbles; grain-supported coarse-grained to very coarse 

grained sand matrix; coal seam 2 m thick 

Sandstone, light-brown to brown; fines upward from fine-grained to very fine grained; oxidized reddishbrown lenses, bluish-gray clay beds, reddish-brown coaly laminations, and coal clasts 

Sandstone, brown, fine- to medium-grained; sandstone beds 10-30 em thick interbedded with bluish-gray 

clay beds 10 em thick; igneous pebbles; zones of reddish-brown, oxidized pebbly sandstone 

Claystone, light- to bluish-gray, shaly; irregular horizontal laminations; pods of coal10-20 em thick and 

1-2 m wide; partly covered 

*U.S. ~ PRINriN:i OFFICE: 1995- 673-Q46/86094 



SELECTED SERIES OF U.S. GEOLOGICAL SURVEY PUBLICATIONS 

Periodicals 

Earthquakes & Volcanoes (issued bimonthly). 

Preliminary Determination of Epicenters (issued monthly). 

Technical Books and Reports 

Professional Papers are mainly comprehensive scientific reports 

of wide and lasting interest and importance to professional scientists and 

engineers. Included are reports on the results of resource studies and of 

topographic, hydrologic, and geologic investigations. They also include 

collections of related papers addressing different aspects of a single scientific topic. 

Bulletins contain significant data and interpretations that are of 

lasting scientific interest but are generally more limited in scope or geographic coverage than Professional Papers. They include the results of resource studies and of geologic and topographic investigations; as well as 

collections of short papers related to a specific topic. 

Water-Supply Papers are comprehensive reports that present significant interpretive results of hydrologic investigations of wide interest 

to professional geologists, hydrologists, and engineers. The series covers 

investigations in all phases of hydrology, including hydrology, availability of water, quality of water, and use of water. 

Circulars present administrative information or important scientific information of wide popular interest in a format designed for distribution at no cost to the public. Information is usually of short-term interest. 

Water-Resources ][nvestigations Reports are papers of an interpretive nature made available to the public outside the formal USGS publications series. Copies are reproduced on request unlike forma] USGS 

publications, and they ar•e also available for public inspection at depositories indicated in USGS catalogs. 

Open-File Reports include unpublished manuscript reports, maps, 

and other material that are made available for public consultation at depositories. They are a nonpermanent form of publication that may be cited in other publications as sources of information. 

Maps 

Geologic Quadrangle Maps are multicolor geologic maps on topographic bases in 7 1/2- or 15-minute quadrangle formats (scales mainly 1:24,000 or 1:62,500) showing bedrock, surficial, or engineering 

geology. Maps generally include brief texts; some maps include structure 

and columnar sections only. 

Geophysical Investigations Maps are on topographic or planimetric bases at various scales, they show results of surveys using geophysical 

techniques, such as gravity, magnetic, seismic, or radioactivity, which reflect subsurface structure:s that are of economic or geologic significance. 

Many maps include comelations with the geology. 

Miscellaneous Im"estigations Series Maps are on planimetric or 

topographic bases of regular and irregular areas at various scales; they 

present a wide variety of format and subject matter. The series also includes 7 1/2-minute qUtadrangle photogeologic maps on planimetric 

bases which show geology as interpreted from aerial photographs. The 

series also includes maps of Mars and the Moon. 

Coal Investigations Maps are geologic maps on topographic or 

planimetric bases at various scales showing bedrock or surficial geology, 

stratigraphy, and structural relations in certain coal-resource areas. 

Oil and Gas Investigations Charts show stratigraphic information for certain oil and gas fie_lds and other areas having petroleum poten- . 

tial. 

Miscellaneous Field Studies Maps are multicolor or black-andwhite maps on topographic or planimetric bases on quadrangle or irregular areas at various scales. Pre-1971 maps show bedrock geology in relation to specific mining or mineral-deposit problems; post-1971 maps 

are primarily black-and-white maps on various subjects such as environmental studies or wilderness mineral investigations. 

Hydrologic Investigations Atlases are multicolored or black-andwhite maps on topographic or planimetric bases presenting a wide range 

of geohydrologic data of both regular and irregular areas; the principal 

scale is 1:24,000, and regional studies are at 1:250,000 scale or smaller. 

Catalogs 

Permanent catalogs, as well as some others, giving comprehensive 

listings of U.S. Geological Survey publications are available under the: 

conditions indicated below from USGS Map Distribution, Box 25286, 

Building 810, Denver Federal Center, Denver, CO 80225. (See latest 

Price and Availability List.) 

"Publications of the Geological Survey, 1879-196l"may be purchased by mail and over the counter in paperback book form and as a set. 

microfiche. 

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"Publications of the U.S. Geological Survey, 1971-1981"may be 

purchased by mail and over the counter in paperback book form (two volumes, publications listing and index) and as a set of microfiche. 

Supplements for 1982, 1983, 1984, 1985, 1986, and for subs~: 

quent years since the last permanent catalog may be purchased by mat 

and over the counter in paperback book form. 

State catalogs, "List of U.S. Geological Survey Geologic and Water-Supply Reports and Maps For (State)," may be purchased by mail and 

over the counter in paperback booklet form only. 

"Price and Availability List of U.S. Geological Survey Publica .. 

tions," issued annually, is available free of charge in paperback bookie•. 

form only. 

Selected copies of a monthly catalog "New Publications of thf'. 

U.S. Geological Survey" is available free of charge by mail or may be obtained over the counter in paperback booklet form only. Those wishing a 

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Note.-Prices of Government publications listed in older catalogs, 

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charged may differ from the prices in catalogs, announcements, and publications.