,,::-:=======:.·:·==I.'===..,;·;:_.::.:;:::.:,:::;;·;:::-:·: Assessment Program· 

illfJI\{~ Background Information to 

}?f~1&~~!lilM;W!l1W!.l[}t~~ Accompany Folio of Geologic 

~~;~~~~~~~~~~ and Resource Maps of the ~l1WMJt~}}JMWf1~~1Wi:if!: C h · · k d S t · k I I d ff;~;f~{:%~t1~~}ru?~\~i:ir 1 g n 1 a n u WI s a n 

The Alaskan Mineral Resource 

Assessment Program: 

Background Information to 

Accompany Folio of Geologic 

and Resource Maps of the 

Chignik and Sutwik Island 

Quadrangles, Alaska 

By R. L. Detterman, J. E. Case, D. P. Cox, D. E. Detra, 

T. P. Miller, and F. H. Wilson 

G E 0 L 0 G I C A L S U R V E Y C I R C U L A R 802 

1981 
United States Department of the Interior 

JAMES G. WATT, Secretary 

Geological Survey 

Doyle G. Frederick, Acting Director 

Library of Congress Cataloging in Publication Data 

The Alaskan mineral resource assessment program 

(Geological SUrvey Circular 802) 

Bibliography: p. 13-16. 

SUpt. of Docs. no.: I 19.4/2:802 

1. Mines and mineral resources--Alaska. I. Detterman, 

Robert L. II. Series. 

QE75.C5 no. 802 [TN24.A4] 557.3s 

[553 109798 14] 

Free on application to Branch of Distribution, U.S. Geological Survey 

604 South Pickett Street, Alexandria, VA 22304 

81-607821 
CONTENTS 

Page 

Abstract --------------------------------------------------------------------- 1 

Introduction ------------------------------------------------------------------ 1 

Purposeandscope ---------------------------------------------------------- 1 Geography and access __ _ _ _ __ _ _ __ _ __ _ __ _ __ _ _ _ _ _ __ _ __ _ _ _ _ _ _ __ _ _ __ _ __ __ __ _ __ _ _ _ 2 

Summary of mineral and petroleum exploration -------------------------- ______ __ 2 

Acknowledgrnen~----------------------------------------------------------- 3 Geologic investigations _ _ _ _ _ _ _ _ __ _ ___ _ __ _ _ _ __ _ _ _ _ _ ___ _ __ _ ___ _ _ _ __ _ __ _ __ __ _ _ _ __ _ __ 3 

Previous investigations_______________________________________________________ 3 

Presentstudy -------------------------------------------------------------- 4 Description of component maps___________________________________________________ 4 

Geology------------------------------------------------------------------- 4 

Geophysics ---------------------------------------------------------------- 5 

Aeromagnetic map and interpretation --------------------------------------- 5 

Geochemistry -------------------------------------------------------------- 5 Gravity map _ _ _ _ __ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ _ __ _ __ _ __ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ __ _ _ _ _ _ __ _ 6 

Mineral resources _ _ _ _ _ _ _ _ _ __ _ _ __ _ __ _ _ _ _ __ __ _ _ _ __ _ __ _ __ _ _ _ _ _ _ _ _ _ _ __ _ _ __ _ _ _ _ __ 7 

Energyresources ----------------------------------------------------------- 8 

Geochronology ------------------------------------------------------------- 9 

Potassium-argon age determinations _________________ ---------------- ___ ____ 9 

lgneousrocks ----------------------------------------------------------- 10 

Megafossil Summary -------------------------------------------------------------- 11 data _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 11 

References-------------------------------------------------------------------- 13 

ILLUSTRATION 

Page 

FIGURE 1. Location and area of the Chignik and Sutwik Island quadrangles, Alaska _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 2 

TABLE 

Page 

TABLE 1. Component maps of the Chignik and Sutwik Island quadrangles mineral and energy resource assessments____ 1 

m 

The Alaskan Mineral Resource Assessment Program: 

Background Information to Accompany Folio of 

Geologic and Resource Maps of the 

Chignik and Sutwik Island Quadrangles, Alaska 

By R. L. Detterman, J. E. Case, D.P. Cox, D. E. Detra, T. P. Miller, and F. H. Wilson 

ABSTRACT 

The Chignik and Sutwik Island quadrangles ( 1:250,000) are 

a part of the Alaska Peninsula in southwestern Alaska. This 

circular and a companion folio of maps represent results of integrated field and laboratory studies by an interdisciplinary 

team on geology, geophysics, geochemistry, mineral resources, geochronology, and energy resources to provide a 

modern assessment of the mineral and energy resources of the 

quadrangles. The maps contain descriptive text, explanatory 

material, tables and diagrams, and pertinent references. This 

circular provides the background data for the mineral and 

energy resource assessment and integrates the component 

maps. A comprehensive bibliography cites both specific and 

general references relevant to the geology and resources of the 

quadrangles. 

INTRODUCTION 

PURPOSE AND SCOPE 

This circular and the companion folio of related 

maps are a part of the series of U.S. Geological 

Survey reports designed to provide a rapid and 

accurate inventory of Alaska's mineral resources. 

The reports furnish information for minerals and 

energy policy-making decisions by Federal, State, 

and industry concerning the future use of Alaskan 

land and resources. This report was prepared 

under the auspices of the Alaska Mineral Resource Assessment Program (AMRAP) by an interdisciplinary team of earth scientists. Field and 

laboratory studies were conducted during 1977 

and 1978. 

The folio consists of 15 maps that provide information on the geology, geochemistry, 

geophysics, geochronology, minerals, and energy 

resources of the Chignik and Sutwik Island quadrangles (table 1). The primary intent of the folio 

and circular is to furnish mineral- and energyresource data for land-use planning and sound 

long-term national resource policy. Additional 

aims are to increase the geologic knowledge of an 

active continental margin and to determine the 

time and type of mineral emplacement. This circu1 

lar contains an extensive bibliography relevant to 

the geologic aspects of the Chignik and Sutwik Island quadrangles, their mineral and energy resources, geochronology, and paleontology. Individual maps in the folio contain references applicable to their subject matter. 

In addition to the folio maps, which are printed 

in black and white, two companion multicolored 

Miscellaneous Geologic Investigations Maps of the 

Chignik and Sutwik Island quadrangles (Detterman and others, 1981) are in press. 

TABLE 1.-Component maps of the Chignik and Sutwiklsland 

quadrangles mineral and energy resource assessment 

U.S. Geological Survey Miscellaneous 

Field Studies ( MF) Map 

Subject 

MF·1053·A (Detterman and others, 1979) ____________ Geology 

·B (Case and others, 1981) _________________ Aeromagnetic map and 

interpretation. 

·C (Detra and Cooly, 1980a) ---------------- Geochemical distribution 

and abundance of cop· 

per. ·D (Detra and Hopkins, 1980) _. ____________ Geochemical distribution 

and abundance of lead. 

·E (Detra and O'Leary, 1980) _______________ Geochemical distribution 

and abundance of zinc. ·F (Detra and Day, 1980) __________________ Geochemical distribution 

and abundance of 

molybdenum. ·G ( Detra and Cooly, 1980 b) _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Geochemical distribution 

and abundance of silver 

and arsenic. · H ( Detra and Cooly, 1980c) _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Geochemical distribution 

and abundance of bis· 

muth, 

tin, and tungsten. 

·I (Tripp and Detra, 1980) ----------------- Mineralogy of heavy· 

mineral concentrates. ·J (Case and others, 1981) _________________ Gravity map. 

·K (Cox and others, 1981) _________________ Mineral resources map 

-L (Detterman and others, 1981) ____________ Energy resources map 

-M (Wilson and others, 1981) ---------------Geochronology map 

-N (Detterman and others, 1981) ------------ Fossil locality map, 

check lists, and 

stratigraphic sections. 

·0 (LeCompte and Steele, 1981) ------------' Landsat map 

GEOGRAPHY AND ACCESS 

The Chignik and Sutwik Island quadrangles include about 19,435 km2 on the Alaska Peninsula 

in southwestern Alaska, approximately 60 percent 
of which is water (fig. 1). The quadrangles are 

bounded by 56° and 57° N. latitude parallels and 

by 156° and 160°34' W. longitude. The area is 

dominated by the massive volcanic edifice of 

Mount V eniaminof and other mountains of the 

Aleutian Range along the south edge and by 

Aniakchak Volcano on the north border. The Aleutian Range borders the Pacific Ocean, and most of 

the peaks are less than 1,000 m in elevation but 

rise nearly vertically from the ocean; Mount Veniaminof ( 2,507 m; 8,225 ft) is the highest peak. 

The Aleutian Range steeply drops off to the west 

onto the nearly flat Bristol Bay Lowland, which is 

mostly less than 30 m in elevation. The lowland 

bordering Bristol Bay is dominated by the spectacular caldera of Aniakchak Volcano, 9.5 km in 

diameter. The caldera contains a 3-km-long lake 

and several cinder cones, the largest of which is 

580 m high. 

Streams draining into the Pacific Ocean are 

generally short and have steep gradients, whereas 

most streams draining to Bristol Bay are shallow 

and sluggish because they are choked with pumice 

and glacial debris. The Meshik River is the largest 

stream and nearly crosses the peninsula; it follows 

a former arm of Bristol Bay that probably cut 

across the peninsula prior to the last major eruption of Aniakchak Volcano about 3,300 to 3,500 

years B.P. (Miller and Smith, 1977). Chignik and 

Black Lakes are remnants of another arm of the 

sea that was closed by pumice and glacial deposits 

from Mount V eniaminof. Most of the area between the lakes and Bristol Bay is 15 m or less in 

elevation. 

Population in the quadrangles is spare and fluctuates considerably with the fishing season. It is 

concentrated almost entirely around the villages 

of Meshik, Chignik, Chignik Lagoon, Chignik 

Lake, and Chignik Flats. There is scheduled air 

transportation into Port Heiden and Port Moller, 

and all the villages have landing strips for small 

planes. A few miles of gravel roads are in use at 

the abandoned Port Heiden Air Force Base. 

SUMMARY OF MINERAL AND PETROLEUM EXPLORATION 

Exploration for minerals and petroleum in the 

quadrangles by industry has revealed no large 

economic deposits to date. Coal is the only mineral resource ever mined and used commercially 

within the area. It was mined for a number of 

years in the early part of this century at the Chignik River and Whalers Creek mines (Atwood, 

1911) for use in canneries at Chignik Lagoon and 

Anchorage Bay. The amount and value of the coal 

produced are not known. 

Early mineral exploration in the quadrangles 

was mainly centered on large alteration areas surrounding porphyry stocks. Claims were staked 

and some exploration was done between 1900 and 

1910 on deposits at Warner Bay, Mallard Duck 

Bay, and Nakchamik Island where copper, lead, 

zinc, and molybdenum minerals and gold are present. Exploration at all localities was small scale 

and sporadic; at Warner Bay it continued until the 

early 1960's. Modern exploration started in 1964 

when Pan American Oil Company did extensive 

diamond drilling on a molybdenum-copper prosFIGURE 1.-Location of Chignik and Sutwik Island quadrangles, Alaska. 

2 
pect in the mountains between the head of 

Braided and Cathedral Creeks. Interest in young 

porphyry copper deposits revived the drilling 

program in 1975 and 1976 when Bear Creek Mining Company drilled several holes on a prospect 

at the head of a tributary of Dry Creek and on 

Home Creek at the head of Mallard Duck Bay. 

Copper was the main mineral commodity of interest at both localities, but the concentration apparently is not high enough to warrant development under current conditions. 

The thick sedimentary rock sequence exposed in 

the mountains has been of great interest to the 

petroleum industry. Starting in the 1950's, many 

major companies investigated the area in detail. 

The exposed rocks are cut by stocks, plugs, dikes, 

and sills, some of which are related to the volcanoes, but some good reservoir and source rocks 

are present. Two wells were drilled, on the Bristol 

Bay lowland where it was hoped that the beds 

would not have been altered by the intrusive 

rocks. Gulf Oil Corporation's Sandy River Federal 

well was completed in 1963 to a depth of 3,983 m 

( 13,068 ft). Numerous shows of oil and gas were 

found below 3,000 m in the upper part of the 

Tolstoi Formation and the lower part of the Bear 

Lake Formation. Good porosity and permeability 

of the sandstone associated with oil and gas shows 

are encouraging for potential petroleum resource 

development. The Gulf Oil Corporation Port 

Heiden Unit drilled in 1972 to a depth of 4,576.5 

m ( 15,015 ft), was dry. 

ACKNOWLEDGMENTS 

Geologic investigations in the Chignik and Sutwik Island quadrangles were facilitated greatly by 

the efforts of many geologists from the U.S. 

Geological Survey and private industry whose 

many contributions are gratefully acknowledged. 

The work of some visiting scientists, short-term 

workers, and laboratory specialists is acknowledged on individual maps in the folio. The contributions of some specialists, although not mentioned specifically on the maps, were of great 

benefit to the project. Among those to whom special tribute is due are J. A. Wolfe, R. A. Spicer, D. 

L. Jones, Louie Marincovich, J. W. Miller, and R. 

W. Imlay, all paleontologists with the U.S. 

Geological Survey whose identifications of many 

collections of invertebrate and plant fossils helped 

unravel the stratigraphic succession of sedimentary units. R. L. Smith and D. H. Richter made a 

3 

significant contribution to an understanding of 

the complex eruption history of Veniaminof and 

Aniakchak Volcanoes. 

The assistance of many people from private industry engaged in minerals and petroleum exploration is appreciated, particularly that of E. D. 

Fields, William Polski, Scott McCoy, A. W. Erxleben, and C. M. Molenaar. Special thanks are also 

due W. C. Bishop and the Bristol Bay Native Corporation for giving us permission to work in the 

area, and for making data available from the drilling program on the copper prospects of the Bear 

Creek Mining Company. 

Work in a remote area such as the Alaska 

Peninsula would be impossible without the able 

assistance of local residents. Among those who 

were of great service to the project were the 

people at Columbia Ward Fisheries at Chignik Lagoon, especially Ben Bender, who provided the 

project with food and lodging during 1977 and 

1978 and aided in many phases of the logistic 

support that made completion of the- project possible. 

Special thanks and commendation are due Captain Roy Roe beck and the crew of the U.S. 

Geological Survey Research Vessel Don J. Miller 

II, who cheerfully provided us with a base of operations for part of 1977 and 1978. Also, to R. W. 

McDonald of ERA Helicopters and Gordon Hines 

of Air Logistics Helicopter Company, who often 

flew in adverse weather to take us to our work 

sites. 

GEOLOGIC INVESTIGATIONS 

PREVIOUS INVESTlGATIONS 

The first geologic publication covering, in part, 

the area of this report on the Alaska Peninsula, 

was a remarkable compilation by Grewingk 

( 1850). For many years his interpretation and 

analysis of the stratigraphy and structure were 

the basis for the geologic interpretations of this 

part of Alaska. Other important generalized contributions to the geology of this part of Alaska 

were made by Dall and Harris ( 1892) and Dall 

( 1896). 

More detailed geologic investigations of the 

Chignik and Sutwik Island area were made by Atwood ( 1911) and Knappen ( 1929). Martin ( 1926) 

made the first major attempt at correlating the 

Mesozoic stratigraphic units of the Alaska Peninsula and showed how they related to those in the 
rest of Alaska. At about the same time, Smith and 

Baker ( 1924) made important contributions to the 

geology of the Chignik area, and Smith ( 1924) 

made the first detailed study of Aniakchak Crater. 

The foundation for the modern interpretation of 

the stratigraphy and structure of the Alaska 

Peninsula, including the Chignik and Sutwik Island areas, was made by Burk ( 1965) during the 

late 1950's for the Richfield Oil Corporation (now 

a part of the Atlantic Richfield Company), one of 

the many major petroleum companies working on 

the peninsula at that time. 

PRESENT S1U DY 

Fieldwork and laboratory analysis for the present study were started in 1977 and completed in 

1978. T. P. Miller and R. L. Smith had started detailed mapping of Anialchak, Black, and Veniaminof Volcanoes in 1974 and 1975, and this 

work was continued during the present investigation. Most of the geologic mapping was at a detailed reconnaissance scale, but sufficient data 

were gathered in some areas to prepare 15-

minute ( 1:63,360) quadrangles. The geologic 

mapping and geochemical sampling were helicopter supported. 

During the course of the investigation, 1 ,455 

stations were occupied for geologic data; 637 

stream-sediment samples and 623 heavy mineral 

pan-concentrate samples were collected. In addition, 448 bedrock samples were collected at 

geologic stations for analysis; these included both 

mineralized samples and unmineralized specimens 

for a background data base. Prior to the present 

study, only two potassium-argon dates were available for the Chignik and Sutwik Island quadrangles (Kienle and Turner, 1976; Armstrong, 

Harakal, and Hollister, 1976). A total of 40 new 

potassium- argon dates have been added by F. H. 

Wilson and M. L. Silberman; these dates permit a 

determination of the time of mineral emplacement (Wilson, 1981). 

Gravity data were collected at many of the 

geochemical sampling sites. In 1977 they were obtained by M. E. Yount, C. D. Holloway, and D. E. 

Detra and in 1978 by D. R. Jefferis. The 

aeromagnetic interpretation map was compiled 

from data flown by LKB Resources, Inc. in 1977 

on U.S. Geological Survey contract. 

4 

DESCRIPTION OF COMPONENT MAPS 

OF THE CHIGNIK AND 

SUlWIK ISLAND QUADRANGLES FOUO 

GEOLOGY (MAP MF-1053-A) 

The Chignik and Sutwik Island quadrangles are 

a part of the Aleutian volcanic arc, a segment of 

an active continental margin. The modern Aleutian volcanic arc is nearly superimposed over an 

earlier Mesozoic magmatic arc. The oldest 

sedimentary rocks exposed in the quadrangles are 

of Middle Jurassic age and were deposited on a 

shelf area in an arc- trench gap basin ( terminology of Dickinson, 197 4) fronting (south of) the 

Mesozoic magmatic arc. Paleomagnetic data indicate that these rocks were deposited considerably 

south of their present latitude (Packer and Stone, 

1974; Stone and Packer, 1979). Igneous activity 

had waned in the Mesozoic arc by the time the 

oldest sedimentary rocks were being deposited, 

and tectonic activity had uplifted som.e of the 

igneous rocks so that they were contributing to 

the sedimentary cycle. Deposition was continuous 

during Jurassic and into Early Cretaceous time, 

and the arc-trench gap basins were nearly filled. 

A period of crustal mobility followed during middle Cretac~ous time, subjecting these basins to 

erosion so that the latest Cretaceous and early 

Tertiary rocks rest uncomformably on the older 

deposits. 

The late Cretaceous through early Tertiary was a 

time of relative quiescence on the Alaska Peninsula. The Semidi Islands batholith was emplaced, 

and a few flows are present in the early Tertiary 

rocks, but the general absence of igneous activity 

suggests that subduction along this part of the 

continental margin had temporarily ceased. Igneous activity started again in late Eocene time and 

continued through at least part of the Oligocene 

with a flood of extrusive and hypabyssal intrusive 

rocks mainly of basaltic to andesitic character, 

which probably indicates renewed subduction 

along the continental margin. The Aleutian volcanic arc started with this pulse. Another quiet interval lasting about 15 m.y. spans the late 

Oligocene and early Miocene. Volcanic and associated intrusive activity greatly increased in late 

Miocene time and has continued to the present. 

The Miocene to Holocene volcanic rocks are 
mainly andesite and dacite. Detritus from these 

volcanic rocks has contributed to the severalthousand-meter thickness of volcaniclastic rock 

deposited in back-arc basins and deltas along the 

north side of the Alaska Peninsula. 

Tectonic activity associated with subduction has 

resulted in numerous thrust and high-angle reverse faults mainly in· the mountainous Pacific 

coast side of the peninsula where there has been 

considerable foreshortening and juxtaposing of 

stratigraphic units. Large scale transverse fracturing is also common. One such fracture trending N. 

40 o W. in the Mount V eniaminof area is marked 

by a cluster of cinder and spatter cones. 

GEOPHYSICS 

AEROMAGNETIC MAP AND INTERPRETATION. 

(MAP MF-1053-B, 2 sheets) 

The aeromagnetic survey of the Chignik-Sutwik 

Island quadrangles is one of the most detailed, 

systematic surveys made across a modern volcanic arc setting, where both Holocene volcanic 

edifices and possible older volcanic centers occur. 

Four main groups of magnetic anomalies have 

been identified in the area. ( 1) Ovoid clusters of 

positive and negative anomalies occur over 

Holocene volcanic edifices at Mount Veniaminof, 

Black Peak, and Aniakchak Crater. ( 2) Ovoid 

clusters of positive and negative anomalies occur 

over volcanic- plutonic complexes near Kujulik 

Bay, Chiginagak Bay, Sutwik Island, and Nakchamik Island. Isotopic ages of igneous rocks 

from these older groups tend to fall into two 

ranges: 38-30 m.y. for the Kujulik Bay and Sutwik 

Island complexes and 10-5 m.y. for the 

Chiginagak Bay and N akchamik Bay complexes. If 

the volcanic complexes are related to subduction 

·in the Aleutian trench, the site of volcanism has 

remained nearly unchanged (within +75 km) 

with respect to the present trench axis since 38 

m.y. ago. ( 3) Large positive ovoid magnetic 

anomalies occur over Tertiary and Quaternary 

igneous rocks that range in age from 38 m.y. to 

about 1.0 m.y. These rocks are dioritic to granitic 

in composition and presumably are related to 

subduction in the Aleutian trench. Several of the 

plutons contain porphyry copper-molybdenum 

deposits, so that their distinctive aeromagnetic 

expression is a regional ore guide. Local areas of 

extreme hydrothermal alteration are expressed by 

flat magnetic gradients or by negative 

aeromagnetic anomalies, and such anomalies are 

a more specific ore guide. ( 4) Broad, gentlegradient anomalies occur over sedimentary basins 

on both the Bristol Bay side and Pacific side of the 

Alaska Peninsula. Local anomalies related to volcanic intercalations or small intrusions are 

superimposed on the deep basin anomalies. The 

basement is 2 km, or deeper, on both the Bristol 

Bay and Pacific margins of the peninsula, but the 

basins are interrupted on both sides of the peninsula by volcanic-plutonic complexes that range in 

age from at least 38 m.y. to 1.0 m.y. 

Chignik anticline, which might appear to be a 

favorable target for exploratory drilling for oil 

and gas, has a core of sedimentary rocks, but 

many small, high-amplitude magnetic anomalies 

in the core region indicate the presence of many 

small intrusive bodies or the presence of volcanic 

rocks of the Meshik Formation below thrust faults. 

Thus, the Chignik anticline should not be considered a major prospect for oil and gas exploration 

until much additional detailed geophysical work· 

has been done. 

GEOCHEMISTRY 

(MAPS M F-1053-C TO I) 

A geochemical survey was made during the 1977 

and 1978 field seasons. The data obtained from 

this survey provided plots showing abundance and 

distribution patterns of specific elements from 

which mineral occurrences of possible economic 

interest were outlined. 

The geochemical investigation was conducted 

over an area covering 18,000 km2 • Streamsediment samples were collected at 637 sites from 

the channels of active streams that were draining 

catchment areas approximately 8 to 12 km2 in 

area. The stream-sediment sample·s were dry 

sieved to minus-80 mesh and- then analyzed for 30 

elements using a semiquantitative emission spectrographic method (Grimes and Marranzino, 

1968). In addition, a fraction of the minus-SOmesh fraction was analyzed for copper, lead, and 

zinc by atomic absorption (Ward and others, 

1969). . 

Heavy-mineral concentrates. were made from 

stream sediment at 623 of the sample sites. A 

, nonmagnetic fraction was obtained from thee 

5 
heavy-mineral concentrate samples and analyzed 

for 31 elements by semiquantitative emission 

spectrography (Grimes and Marranzino, 1968). 

Analytical data, a comprehensive description of 

sample preparation and analysis, and a statistical 

summary of these results, for stream-sediment 

and heavy-mineral concentrate samples, have 

been presented in an Open-File Report ( Detra 

and others, 1978 a,b). 

The distribution and abundance of copper ,lead, 

zinc, molybdenum, silver, arsenic, bismuth, tin, 

and tungsten in nonmagnetic heavy-mineral concentrate and minus-80 mesh stream-sediment 

samples are presented on Miscellaneous Field 

Studies Maps that accompany this circular ( Detra 

and others, 1980 a,b,c). Maps showing the distribution of selected minerals found in the nonmagnetic fraction of heavy-mineral concentrate 

samples are also presented (Tripp and Detra, 

1980). 

The nonmagnetic fraction of heavy-mineral concentrate samples proved to be the most useful 

.-;··sample medium for outlining potential mineral 

occurrences because dilutional effects produced 

by the presence of common rock-forming minerals and barren rock fragments making up the bulk 

of the stream sediment are significantly reduced. 

The isolation of this heavy-mineral fraction effec· 

tively improved the contrast between backgrouna 

and anomalous values obtained by spectrographic 

analysis. 

An effort was made to determine background 

concentrations of specific elements in the major 

rock units as described on the geologic map (Detterman and others, 1979). Representative rock 

samples were collected and analyzed using the 

semiquantitative spectrographic method. Statistical data based on the analytical results appear, 

where applicable, on the element plots (Detra and 

others, 1980). The intended purpose is to provide 

a basis of comparison between the anomalous 

ranges of element content determined for stream 

sediments and heavy-mineral concentrates and 

that of the source rocks from which the sediment 

was derived. 

The most significant anomaly patterns on the 

geochemical maps outline occurrences of copper, 

molybdenum, zinc, and other associated elements 

of interest. Some specific localities are Cape Kumlik, Cathedral Creek, and Warner Bay areas, 

where mineralization is associated with Tertiary 

intrusive rocks. 

GRAVITY MAP (MAP MF-1053-J) 

The simple Bouguer anomaly map of the Chignik and Sutwik Island quadrangle is dominated by 

several northeast-trending gravity highs having 

values of +30 to more than +50 mgals. A relative 

gravity low having values of 0 to-10 mgals occur 

over the Bristol Bay Basin in the Bristol Bay Lowlands. According to Barnes' gravity anomaly map 

( 1977), Bouguer anomalies offshore in Bristol 

Bay to the northwest are about +20 to +30 

mgals, so the residual gravity low over the basin 

is about 30 mgals with respect to the Bristol Bay 

shelf. From the positive anomaly over the peninsula, gravity values decrease southward to values 

of +20 mgals at Sutwik Island, to +10 mgals at 

the Semidi Islands, and to -30 mgals near the east 

edge of the map. Immediately southeast of the 

map area, over the Shumgin Basin, which contains as much as 2 km of stratified sedimentary 

rocks, Bruns and von Huene ( 1977) reported a 

gravity low of about -20 mgals. Separating the 

gravity low of the Bristol Bay Lowlands from the 

high over the mountainous parts of the peninsula 

is a major northeast-trending zone of steepened 

gravity gradient that reflects a major late Tertiary 

tectonic boundary that may represent a rejuvenated feature as old as Jurassic (Bruin Bay fault). 

The general gravity low over the basin beneath 

the Bristol Bay Lowlands is consistent with the 

great thickness of Tertiary sedimentary rocks that 

occurs in the basin. Drill holes have penetrated 

about 4,000-4,500 m of Tertiary sedimentary and 

volcanic rocks. 

Southwest of Mount Veniaminof, a positive 

gravity nose, having values greater than +50 

mgals, is the northeast end of a major gravity 

high that extends far to the southwest along the 

Alaska Peninsula and continues into the Aleutian 

Islands (Barnes, 1977). Values in excess of +80 

mgals to the southwest strongly suggest that the 

crust is oceanic rather than continental. 

A second major gravity high coincides very 

closely with the Chignik anticline. Structural relief, for example at the base of the Tertiary rocks, 

across the southeast flank of the anticline is as 

much as 3,000 m from Castle Bay to the anticlinal 

crest (Burk, 1965, fig. 22), and structural relief 

from the Port Heiden well in the Bristol Bay Lowlands to the crest of the anticline (where Jurassic 

strata are exposed) is at least 5,500 m and may be 

7,500 m or more. Again, simple Bouguer 

6 
anomalies in excess of +50 mgals are suggestive 

of oceanic rather than continental crust, especially where the stations are in mountainous terrane. 

One of the more significant anomalies of the 

area, from a mineral resource viewpoint, is a 

negative anomaly of -10 to -15 mgals in the 

Warner Bay-Devils Bay-Kuiukta Bay region in the 

southeast part of the Chignik quadrangle that 

generally coincides with the complex of granitic 

plutonic rocks of the area. The granitic rocks contain copper and molybdenum mineralization at 

several localities, especially at Warner Bay. It 

seems evident that the granitic rocks, which have 

been extensively altered, are considerably less 

dense than the adjacent rocks that they intrude; 

wallrocks include considerable hornfels. 

No deep crustal refraction measurements have 

been made in this part of Alaska, so the gravity 

data provide the main geophysical basis for speculation about crustal composition and thickness. 

The strongly positive gravity anomalies over the 

Aleutian Islands extend northeast along the 

peninsula to about lat 58° N., near Becharof Lake, 

in the Ugashik quadrangle. A major negative 

anomaly in the vicinity of Katmai National Park 

continues northeastward into Cook Inlet and 

beyond to the Matanuska Valley (Barnes, 1977). 

Using the empirical relations between Bouguer 

anomalies and mean elevation, derived by Woollard and Strange ( 1962) and Deminitskaya and 

Belyaevsky ( 1969), we suggest that oceanic crust 

forms the pre-Triassic basement of the peninsula 

south of Becharof Lake and continental or transitional crust north of Becharof Lake. 

MINERAL RESOURCES MAP (MAP MF-1053-K) 

Many areas within the Chignik-Sutwik Island 

quadrangles have a high potential for discovery of 

porphyry copper-molybdenum deposits. One such 

deposit called Bee Creek was drilled in 1976 by 

Bear Creek Mining Company in cooperation with 

Bristol Bay Native Corporation, and the drill core 

and drilling records were made available to the 

U.S. Geological Survey for study. At Bee Creek, 

disseminated chalcopyrite and molybdenite are 

associated with intense biotite alteration of arkosic graywacke of the Jurassic Naknek Formation intruded by a small quartz diorite stock. Although the prospect has all of the characteristics 

of a porphyry-type deposit (intense fracturing, 

7 

biotite alteration, abundant halite- bearing fluid 

inclusions), both tonnage and metal grade, as revealed by drilling, are low, and no further work 

has been done. Five other mineral occurrences 

suggesting porphyry- type deposits are known in 

the two· quadrangles. 

Studies of the distribution of metallic elements 

in fine- grained stream sediments and nonmagnetic heavy-mineral concentrates of stream sediments have revealed significant anomalies in arsenic, bismuth, copper, gold, lead, molybdenum, 

silver, tin, tungsten, and zinc. When these metal 

anomalies were plotted on the map within the 

drainage areas in which they occur, a distinct 

clustering was evident, and metal anomalies 

within clusters were found to be distributed in a 

zonal order. Molybdenum, copper, and locally, 

tungsten anomalies occur in centrally located 

drainage areas that are flanked or surrounded by 

drainage areas containing anomalous copper, 

lead, zinc, arsenic, silver, or gold. Some clusters 

have an outer fringe of drainage areas containing 

anomalous bismuth and tin. 

Centrally located copper and molybdenum 

anomalies coincide with the Bee Creek deposit 

and five other porphyry-type mineral occurrences. Seven other copper-molybdenum 

anomalies are suspected to have been derived 

from concealed or otherwise undetected 

porphyry-type mineral occurrences. 

Flanking and peripheral metal anomalies are believed to be derived from small veins deposited in 

a zonal pattern around volatile-rich igneous plutons where porphyry-type mineralization may 

have taken place. The zoning of the groups of 

elements is caused by the stability of their sulfide 

minerals in hydrothermal fluids at decreasing 

temperatures relative to increasing distance from 

the plutonic-hydrothermal heat source. 

The zoning patterns revealed in this study indicate that the hydrothermal mineralization effects 

of volatile-rich plutons may extend outward as 

much as 10 km. The zoning patterns also indicate 

that most, if not all, anomalies of the 10 metals 

cited above are due to hydrothermal activity, and 

the presence of deposits of these metals formed 

by other processes can be effectively ruled out. 

Finally, recognition of 13 distinct clusters of 

anomalies with copper-molybdenum-rich central 

zones makes it possible to narrow the probability 

limits associated with estimates of the number of 

undiscovered porphyry deposits in the study area. 
The possibility of sedimentary uranium deposits 

in the Chignik and Sutwik Island quadrangles 

cannot be disregarded even though no supporting 

mineralogic or geochemical evidence for such deposits was revealed in this study. The sedimentary 

and structural environments of the Chignik ( Cretaceous), Tolstoi (Paleocene and Eocene), and 

Bear Lake (Miocene) Formations were compared 

with the Regional Western States Sandstone 

Uranium Model (Racklay, 1976) using the PROSPECTOR computer model implemented by John 

Gaschnig at Stanford Research Institute (see 

Gaschnig, 1980). Both the Chignik and Tolstoi 

Formations received high values for favorability 

for occurrence of roll-front type uranium deposits. Unfavorable features were the absence of 

direct evidence of mineralization and the degree 

of structural tilting and folding of the units. The 

dacitic to andesitic composition of tuff beds interlayered with these units may also be an unfavorable feature since most uranium deposits are 

genetically associated with more felsic tuffaceous 

deposits. 

Values resulting from application of this program to field data from the study area are expressed as degree of certainty with which the field 

data fit the model. A perfect fit is +5, insufficient 

information is zero, and a perfect nonfit is -5. 

Values for the three formations are as follows: 

Bear 

Chignik Tolstoi Lake 

Formation Formation Formation 

Favorable tectonic 

and other regional conditions _ _ _ _ _ _ _ _ _ _ _ 3.59 

Favorable sedimentary 

environment _________ 4.81 

Favorable 

mineralization and 

alteration _ _ _ _ _ _ _ _ _ _ _ _ 1.08 

Overall favorability 

for Western States 

sandstone uranium 

deposits _ _ _ _ _ _ _ _ _ _ _ _ _ 2.91 

4.01 

4.68 

.58 

2.28 

ENERGY RESOURCES (MAP MF-1053-L) 

4.32 

3.64 

.19 

1.06 

Energy resources investigations of the Chignik 

and Sutwik Island quadrangles included: detailed 

measurement of selected representative sections 

of sedimentary rock to determine origin, depositional environment, and post-depositional alter ation; collection of samples for porosity, permeability, organic carbon, total carbon, and degree of 

maturation as an indication of their petroleum potential; mapping the location and extent of all coal 

and carbonaceous shale beds and collection of 

samples for analysis; investigation of the 

Holocene volcanic centers as potential geothermal 

sites. 

Sections of the Naknek, Chignik, Tolstoi, and 

Bear Lake Formations were measured in detail; 

other sections are generalized. These stratigraphic units are the main sandstone sequences 

that could be potential source or reservoir rock. 

The lower sandstone unit of the Naknek Formation is about 68 percent arkosic sandstone mainly 

of fluvial, fluvial deltaic, and beach depositional 

environment. Samples checked for porosity and 

permeability were uniformly low- about 1.1 percent porosity and 0.01 md permeability. Postdepositional diagenesis is the main cause of the low 

values in the Naknek Formation. The foreshore to 

fluvial deltaic cyclic sequence of the Chignik 

Formation produced sandstones with somewhat 

better values; the range in porosity was from 1.0 

to 8.0 percent and permeability from 0.20 to 2.06 

md. A typical section at Chignik Lagoon (Detterman, 1978) is about 56 percent sandstone and 

conglomerate. The few samples collected from the 

Tolstoi Formation had about the same range as 

the Chignik samples. By far, the highest values 

were found in the few samples collected from the 

Bear Lake Formation. Ranges were from 15.1 to 

18.2 percent porosity and 333 to 520 md permeability. 

Shale and siltstone samples from the Chignik, 

Hoodoo (Cretaceous), and Tolstoi Formations 

were analyzed for carbon content and degree of 

maturation. The carbon content of samples from 

the Chignik ranged between 0.53 and 29.65 percent, values for the Hoodoo were 0.48 to 9.82, 

and those for the Tolstoi ranged between 4.93 and 

8.8 7 percent. Maturation data have not been determined, but coal from the Chignik Formation is 

classified as high-volatile B bituminous (Conwell 

and Triplehorn, 1978), which indicates a degree of 

maturation that would produce oil and gas. The 

presence of oil-saturated sandstone in the Chignik 

Formation at Chignik Lagoon (Keller and Cass, 

1956) indicates that hydrocarbons have been generated. 

8 

Coal beds crop out throughout the area underlain by rocks of the nonmarine cycles of the Chignik and Tolstoi Formations. Most of the coal occurs in beds 0.3 to 1 m thick, generally with three 
to five beds separated by shale and bone at any 

one locality. Beds are locally as thick as 3 m. 

Analysis of coal from the Chignik Formation 

(Conwell and Triplehorn, 1978) indicates that it is 

high -volatile B bituminous with a high ash content 

and a BTU value of about 12,000. Coal from the 

Tolstoi Formation is untested but appears to be of 

slightly lower grade. 

Carbonaceous shale, also, is common throughout the Tolstoi Formation, and thin seams of coal 

and carbonaceous shale are found in parts of the 

Bear Lake Formation. 

The rank of the coal in the Chignik Formation 

indicates a degree of maturation that would produce oil and gas in the same rocks provided that a 

source were present; the analyses of the samples 

suggest that a source exists. The point of 

maximum oil and gas generation occurs at the 

same point that produces high-volatile B bituminous coal (Dow, 1977). Local oil staining of 

sandstone of the Chignik Formation at Chignik 

Lagoon indicates that some petroleum has been 

generated. However, the chance of finding a 

major oil field is greatly reduced by the presence 

of numerous stocks and plugs intruded into the 

sedimentary sequence. Interpretation of the 

aeromagnetic map (MF-1053-B, Case and others, 

1981, this folio) indicates that intrusive rocks 

probably are present in the core of some structures. 

Four large volcanic centers of Quaternary age 

occur in the Chignik- Sutwik Island study area, 

and at least three have high potential for geothermal energy. Aniakchak and V eniaminof Volcanoes are caldera systems whose youthfulness, 

size, and past volcanic history strongly indicate a 

large, near-surface heat reservoir. Smith and 

Shaw ( 1975) have calculated a heat content of 

129x 1018 cal for Aniakchak Volcano and 115x1018 

cal for V eniaminof Volcano. 

Black Peak is a smaller volcanic center that, 

however, represents a very long-lived igneous system with recent volcanic activity from a nearsurface magma chamber. The heat content associated with this chamber has been estimated at 

12x1018 cal by Smith and Shaw ( 1975). 

Kupreanof Volcano, although not yet completely 

mapped, appears to be a large stratovolcanic 

complex that, unlike the other three volcanic centers, has not yet been the site of explosive silicic 

volcanism. The occurrence of at least two major 

sites of fumarolic activity and recent silicic dacitic 

9 

flows may indicate that a near-surface magma· 

chamber is forming with a resulting reservoir. 

GEOCHRONOLOGY (MAP MF-1053-M) 

POTASSIUM-ARGON AGE DETERMINATIONS 

As part of the Chignik-Sutwik Island AMRAP 

project, potassium-argon studies of igneous rocks 

were undertaken. Two strategies were used in dating: ( 1) dating of primary minerals or whole rocks 

to determine crystallization ages and ( 2) dating of 

secondary or hydrothermal minerals to determine 

the time of alteration and mineralization. 

For whole-rock samples, other than quartzsericite samples, preparation was by crushing to 

60-100 or 100-200 mesh, depending on mineral 

grain size, followed by a hydrofluoric acid leaching. The leaching process removes secondary minerals and glass and etches the remainder. Experimentally, this procedure has been shown to 

dramatically increase the relative percent 

radiogenic argon in the sample while apparently 

not affecting the determined age ( M. L. Silberman, oral commun., 1978). This measurably decreases the analytical error in the age determination. 

Rocks that were to be processed to yield mineral 

separates were crushed, washed, separated using 

methylene iodide for density separation, a Franz 

Isodynamic Separator1 for magnetic separation, 

and a vibrating inclined table for separation of 

platy minerals. Purities of the mineral separates 

in most cases exceeded 99 percent. Splits of these 

separates were then made for potassium analysis 

and argon extraction. 

Argon extraction and mass spectrometry were 

carried out in the U.S. Geological laboratories in 

Menlo Park, California, generally following the 

methods of Dalrymple and Lanphere ( 1969). Paul 

Klock was the potassium analyst, and all analyses 

were made by flame photometry using a lithium 

metaborate flux and lithium internal standard 

(Engels and Ingamells, 1970). All potassium 

analyses were in duplicate, and most wer.e in 

quadruplicate. 

1 Any use of trade names is for descriptive purposes only and does not imply endorsement by the U.S.Geological Survey. 
As of July, 1976, all potassium-argon age determinations from the U.S. Geological Survey are 

reported using the following new isotope abundance and decay constants: 

Ae = 5.72 X 10·11 year·1 

Ae' = 8.78 X 10-13 year· 1 

X p = 4.93 x 10-10 year· 1 

4

0Jc1Ktotal < 1.167 x 10·4 mol/mol 

(Beckinsale and Gale, 1969; Garner and others, 

1975). The age equation resulting from use of 

these constants is: 

t(yrs) = 1.804 X 109 /n (9.541( 40Ar/4°K) + 1.0). 

For ages between 1 and 100 m.y. this change adds 

approximatly 2 percent to ages calculated using 

the previous constants. 

IGNEOUS ROCKS 

Intrusive rocks in the area range in age from 

Paleocene to Quaternary. The igneous terminology used here follows that of Streckeisen ( 1976, 

1979). Many hypabyssal rocks are plutonic in 

form and texturally intermediate between volcanic and plutonic; volcanic names are used for 

these. Compositionally they range from leucobasalt to dacite, although the bulk are near andesite in composition. Most intrusive rocks are 

hypabyssal; relatively deep seated plutons are 

represented by three major occurrences; ( 1) the 

large late Miocene quartz diorite(?) body extending along the coast to the northeast from 

Chiginagak Bay in the Sutwik Island and Ugashik 

quadrangles; ( 2) the Devils batholith, a late 

Miocene granodiorite to tonalite multiphase intrusive body south of Chignik centered on Devils Bay 

in the Chignik quadrangle; and ( 3) the Paleocene 

biotite granodiorite (Kienle and Turner, 1976) in 

the Semidi Islands in the Sutwik Island quadrangle. Minor occurrences of plutonic rocks include a number of small tonalite bodies at Mallard 

Duck Bay. 

The exposed intrusive rocks of the study area 

can be considered the roots of eroded volcanoes, 

and as such they tend to be saturated with silica 

and poor in alkali. The intrusive rocks commonly 

are closely associated with volcanic rocks. The 

major mafic mineral is hornblende, though 

pyroxene and biotite are also present. No rocks, 

other than eroded debris of the Alaska-Aleutian 

Range batholith, were found to contain primary 

muscovite. Primary biotite and potassium 

feldspar are rare in all but the Devils batholith. 

The volcanic rocks mapped as the Meshik Formation are dacitic to leucobasaltic flows, agglomerates, and breccias. These are usually hydrothermally altered, although in a number of 

areas, fresh, columnar- jointed andesite and dacite plugs are included in the formation. Several 

of these plugs have been dated at 35 to 30 m.y., 

thereby providing a probable upper limiting date 

on the formation. The samples dated range in 

composition from hornblende dacites to two 

pyroxene andesites. 

In several areas, particularly on Cape Kumlik 

and Kumlik Island, hypabyssal hornblende 

leucobasalt and andesite porphyry plutons intrude 

sedimentary rocks of the Tolstoi Formation. 

Potassium-argon ages of these intrusions, all of 

which cluster about 35 m.y. (Oligocene) (samples 

77AWs 30, 40, 46, 74, 78AWs 17, 18, and 24), indicate that the intrusions may be the roots of volcanoes that were sources for some of the volcanic 

rocks of the Meshik Formation. The previously 

mentioned dacite and andesite plugs may also be 

necks of volcanoes that were sources for some of 

the Meshik Formation. 

On Cape Kumlik and Kumlik Island, several 

hypabyssal hornblende andesite and leucobasalt 

pophyry intrusives are found. Each of these rocks 

is associated with areas of extensive alteration 

and possible mineralization. Phenocrystic amphibole is the dominant mafic mineral in all of 

these rocks; however, a few samples contain relicts or pseudomorphs of pyroxene. The 

groundmasses of these rocks are fine grained and 

are composed of plagioclase feldspars and opaque 

minerals. Potassium- argon age determinations on 

the amphiboles range from 39.1 +2.54 to 

34.2+2.07 m.y. (Eocene and Oligocene), indicating that the hypabyssal bodies are approximately 

coeval with the Meshik Formation. 

Similar to these rocks are the intrusive rocks 

found on Cape Kunmik. At Cape Kunmik, autoliths of pyroxene and amphibole are quite 

common and from a distance give the rock a porphyritic appearance. Mineralization and alteration 

of the surrounding country rocks are not so extensive as at Cape Kumlik. A potassium-argon age 

of 33.5+2.33 m.y. (Oligocene) has been determined on a green pleochroic amphibole from a 

10 
hornblende andesite where the plagioclase is so 

altered as to be virtually unrecognizable. 

A very strongly altered rock mass that was apparently a biotite-hornblende dacite dome was 

found on the northwest side of Sutwik Island. This 

is one of the few rocks in the study area with 

primary biotite. Alteration of the plagioclase is 

such that the composition is indeterminate; 

hornblende has been resorbed or altered to calcite 

and opaques. Quartz is common and apatite is extremely abundant. The biotite appears quite fresh 

and has yielded a potassium-argon age of 

34.5+1.66 m.y. (Oligocene). 

Pinnacle Mountain, near Meshik Lake, is a 

hornblende andesite(?) porphyry pluton intruding 

the Tolstoi and Meshik Formations. The texture is 

porphyritic, and the fine-grained groundmass 

composes about 50 percent of the rock. A 

potassium-argon age of 34.5+0.85 m.y. was determined on hornblende from this rock. 

A plagioclase separate from a two-pyroxene 

andesite from near N akalilok Bay in the Sutwik Island quadrangle yielded an age of 48.1 +o.89 m.y. 

The texture is porphyritic; plagioclase composes 

the bulk of the phenocrysts and pyroxene primarily in the groundmass. 

Throughout the study area are many intrusive 

and volcanic rocks of late Tertiary age, particularly near presently active volcanoes. These include numerous volcanic rocks around Mount 

Veniaminof, most of the small intrusive bodies 

associated with alteration zones, and other scattered intrusive bodies in the northeastern part of 

the Sutwik Island quadrangle. 

Most of the small intrusive bodies are petrographically similar. Either phenocrystic 

hornblende and (or) hypersthene or augite are 

the mafic mineral ( s); they have resorted edges 

and are probably partially chloritized. The 

plagioclase, where it can be determined, is of 

An45-55 composition, and is usually much altered. Quartz may or may not be present in the 

groundmass or as phenocrysts. The texture is 

porphyritic with a fine-grained to aphanitic 

groundmass and phenocrysts of plagioclase and 

the mafic mineral. 

A hornblende separate from a sample of an 

andesite sill collected at Anchorage Bay near 

Chignik yielded a 16.5+1.48 m.y. age. The dated 

sample is hydrothermally altered, with strongly 

sericitized and kaolinized feldspars both in 

phenocrysts and groundmass. The amphibole is 

pleochroic in deep browns and has resorbed 

edges; the clinopyroxene is very pale green and 

has sharp subhedral grain boundaries. This rock, 

one of the very few that has been dated, has an 

age between 10 and 20 m.y., which is considered a 

minimum age. 

A dating sample collected from the north edge 

of the Sutwik Island quadrangle is a hornblende 

hypa-andesite that is virtually a perfect match for 

the late Tertiary rocks. The amphibole is in good 

condition and has yielded an age of 19.4 +0.16 

m.y. The feldspar is nearly completely altered to 

sericite; what remains is strongly zoned with 

Carlsbad and minor albite twinning. 

SUMMARY 

The geochronologic work undertaken here has 

indicated two important Tertiary magmatic 

episodes in the Chignik-Sutwik Island area. These 

episodes may correspond to similar events in the 

Aleutian Island (DeLong and others, 1978) 

though here they occur about 5 to 10 m.y. later. 

This lapse may be related to the propagation rate 

along the Aleutian Trench. One episode, occurring 

about 34 m.y., represents the Tolstoi-Meshik arc. 

The large volume and wide distribution of volcaniclastic rocks of the Tolstoi Formation and volcanic rocks of the Meshik Formation tend to confirm the importance of this event. 

MEGAFOSSIL DATA MAP (MF-1053-N) 

A considerable amount of new data on the fossil 

megafauna and flora was obtained during the 

present investigations. About 200 collections, 

many of them from areas that had never been collected, added considerably to the data base for 

this part of Alaska and helped greatly in the interpretation of the stratigraphy. Fossils were collected from rocks ranging in age from Middle 

Jurassic (Callovian) to late Miocene (Wishkahan). 

The localities shown on the map and the fossils 

listed in the tables were all collected during 1977 

and 1978. Previous Mesozoic (post-Callovian) collections in the area are listed in Jones and Miller 

( 1976). The Middle Jurassic (Callovian) fossils 

are of particular interest as they extend the 

known area of exposed Shelikof Formation 

(Jurassic) 150 km to the southwest down the 

11 
Alaska Peninsula. The many excellent collections 

of Tertiary plants will add greatly to our knowledge of the flora of this area and include many 

new undescribed genera and species. 

The large collections of late Tertiary mollusks 

were identified by L. N. Marincovich of the 

Geological Survey and the echinoids by C. W. Allison of the University of Alaska, Fairbanks, 

Alaska. The numerous specimens of early and 

middle Tertiary megaflora were identified by J. A. 

Wolfe of the Geological Survey, and the Late Cretaceous specimens by R. A. Spicer, Imperial College, London, England. J. W. Miller and D. L. 

Jones of the Geological Survey identified the Cretaceous megafauna and the Jurassic pelecypods. 

The Jurassic ammonites were identified by R. W. 

Imlay. 

12 
REFERENCES 

Starred references indicate those cited 

in this report 

Part 1. Specific References (Principally restricted to the 

Chignik and Sutwik Island quadrangles or references in 

which the quadrangles constitute a significant part of the 

report.) 

*Atwood, W. W., 1911, Geology and mineral resources of parts 

of the Alaska Peninsula: U.S. Geological Survey Bulletin 

467, 137 p. 

Berryhill, R. V., 1963, Reconnaissance of beach sands, Bristol 

Bay, Alaska: U.S. Bureau of Mines Report of Investigations 6214, 4S p. 

*Burk, C. A., 1965, Geology of the Alaska Peninsula--Island 

arc and continental margin (Part 1): Geological Society of 

America Memoir 99, 250 p. 

*Case, J. E., Cox, D.P., Detra, D. E., Detterman, R. L., and 

Wilson, F. H., 19Sl, Maps showing aeromagnetic survey 

and interpretation of the Chignik and Sutwik Island 

quadrangles, Alaska: U.S. Geological Survey Miscelhineous Field Studies Map MF-1053-B, scale 1:250,000, 2 

sheets (in press). 

*Case, J. E., Barnes, D. F., Detterman, R. L., Morin, Robert, 

and Sikora, Robert, 19Sl, Gravity anomaly and interpretation map of the Chignik and Sutwik Island quadrangles, 

Alaska: U.S. Geological Survey Miscellaneous Field 

Studies Map MF-1053-J, scale 1:250,000 (in press). 

Cobb, E. H., 1972, Metallic mineral resources map of the 

Chignik quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-374, scale 1:250,000. 

*Cmiwell, C. N., and Triplehorn, D. M., 197S, Herendeen 

Bay-Chignik coals, southern Alaska Peninsula: State of 

Alaska Department of Natural Recources, Special Report 

s, p. 15. 

*Cox, D.P., Detra, D. E., and Detterman, R. L., 19Sl, Mineral 

resource maps of the Chignik and Sutwik Island quadrangles, Alaska: U.S. Geological Survey Miscellaneous 

Field Studies Map MF-1053-K, 2 sheets, scale 1:250,000. 

*Dall, W. H., 1S96, Report of coal and lignite of Alaska: U.S. 

Geological Survey Annual Report. 17th, 1, p. 763-90S. 

*Dall, W. H., and Harris, G. D., 1S92, Correlation papers: 

Neocene: U.S. Geological Survey Bulletin S4, 349 p. 

*Detra, D. E., and Cooley, E. F., 19SOa, Distribution and 

abundance of copper in minus-SO-mesh stream-sediment 

and nonmagnetic heavy-mineral- concentrate samples, 

Chignik and Sutwik Island quadrangles, Alaska: U.S. 

Geological Survey Miscellaneous Field Studies Map MF1053-C, 2 sheets, scale 1:250,000. 

*--19SOb, Distribution and abundance of silver and arsenic 

in _no~magnetic heavy-mineral-concentrate samples, 

Chigmk and Sutwik Island quadrangles, Alaska: U.S. 

Geological Survey Miscellaneous Field Studies Map MF1053-G, 2 sheets, scale 1:250,000. 

Detra, D. E., Cooley, E. F., Day, G. E., O'Leary, R. M., Holloway, C. D., and Yount, M. E., 197S, Results and statistical summary from analysis of stream sediment and 

heavy-mineral-concentrate samples, Chignik and Sutwik 

Island quadrangles, Alaska: U.S. Geological Survey 

Open-File Report 7S-345, 96 p. 

*Detra, D. E., Cooley, E. F., Hopkins, R. T., Jr., O'Leary, R. 

M., and Jefferis, D. R., 197S, Final results and statistical 

summary from analysis of stream-sediment and heavy13 

mineral-concentrate samples, Chignik and Sutwik Island 

quadrangles, Alaska: U.S. Geological Survey Open-File 

Report 7S-1090, 105 p. 

*Detra, D. E., and Cooley, E. F., 19SOc, Distribution and 

abundance of bismuth, tin, and tungsten in nonmagnetic 

heavy-mineral-concentrate samples, Chignik and Sutwik 

Island quadrangles, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-1053-H, scale 

1:250,000. 

*Detra, D. E., and Day, G. W., 19SO, Distribution and abundance of molybdenum in minus-SO-mesh streamsediment and nonmagnetic heavy- mineral-concentrate 

samples, Chignik and Sutwik Island quadrangles, Alaska: 

U.S. Geological Survey Miscellaneous Field Studies Map 

MF-1053-F, 2 sheets, scale 1:250,000. 

*Detra, D. E., and Hopkins, R. T., Jr., 19SO, Distribution and 

abundance of lead in minus-SO-mesh stream-sediment 

and nonmagnetic heavy-mineral- concentrate samples, 

Chignik and Sutwik Island quadrangles, Alaska: U.S. 

Geological Survey Miscellaneous Field Studies Map MF1053-D, 2 sheets, scale 1:250,000. 

*Detra, D. E., and O'Leary, R. M., 19SO, Distribution and 

abundance of zinc in minus-SO-mesh stream-sediment 

and nonmagnetic-heavy-mineral concentrate samples, 

Chignik and Sutwik Island quadrangles, Alaska: U.S. 

Geological Survey Miscellaneous Field Studies Map MF1053-E, 2 sheets, scale 1:250,000. 

*Detterman, R. L., 197S, Interpretation of depositional environments in the Chignik Formation, Alaska Peninsula, in 

Jonson, K. M., ed., The United States Geological Survey 

in Alaska: Accomplishments during 1977: U.S. Geological 

Survey Circular 772-B, p. B62-B63. 

*Detterman, R. L., Case, J. E., Miller, T. P., and Yount, M. E., 

19Sl, Energy resource maps of the Chignik and Sutwik 

Island quadrangles, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-1053-L, 3 sheets, scale 

1:250,000 (in press). 

*Detterman, R. L., Miller, T. P., Yount, M. E., and Wilson, F. 

H., 1979, Generalized geologic map of the Chignik and 

Sutwik Island quadrangles, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-1053-A, scale 

1:250,000. 

-19Sl, Geologic map of the Chignik and Sutwik Island 

quadrangles, Alaska: U.S. Geological Survey Miscellaneous Geologic Investigations Map I -1229, scale 1:250,000 

(in press). 

--19Sl, Quaternary geologic map of the Chignik and Sutwi_k Island quadrangles, Alaska: U.S. Geological Survey 

Miscellaneous Geologic Investigations Map I -1292, scale 

1:250,000 (in press). 

*Detterman, R. L., Yount, M. E., and Case, J. E., 19Sl, 

Megafossil sample locality map, checklists, and stratigraphic sections for the Chignik and Sutwik Island quadrangles, Alaska: U.S. Geological Survey Miscellaneous 

Field Studies Map MF-1053-N, 2 sheets, scale 1:250,000 

(in press). 

Fairchild, D. K. T., 1977, Paleoenvironments of the Chignik 

Formation, Alaska Peninsula: College, University of 

Alaska, M.S. thesis, 16S p. 

Jones, D. L., 1963, Upper Cretaceous (Campanian and Maestrichtian) ammonites from southern Alaska: U.S. Geological Survey Professional Paper 432, 53 p. 

*Jones, D. L., and Miller, J. W., 1976, Preliminary geologic 

map of the Alaska Peninsula showing post-Callovian 

Mesozoic fossil localities: U.S. Geological Survey OpenFile Report 76-76, 2 sheets, scale 1:500,000. 
*Keller, A. S., and Cass, J. T., 1956, Petroliferous sand of the 

Chignik Formation at Chignik Lagoon, Alaska: U.S. 

Geological Survey Open-File Report 56-71, 5 p. 

*Kienle, Juergen, and Turner, D. L., 1976, The ShumaginKodiak batholith-- A Paleocene magmatic arc?: State of 

Alaska Department of Natural Resources, Geology Report 

51, p. 9-11. 

*Knappen, R. S., 1929, Geology and mineral resources of the 

Aniakchak district: U.S. Geological Survey Bulletin 797, 

p. 161-227. 

LeCompte, J. R., and Steele, W. C., 1981, Maps showing interpretation of Landsat imagery of the Chignik and Sutwik Island quadrangles, Alaska: U.S. Geological Survey 

Miscellaneous Field Studies Map MF-1053-0, 2 sheets, 

scale 1:250,000. 

Lyle, W. M., and Dobey, P. 1., 1973, Geology and mineral 

evaluation of the Aniakchak drainage, Alaska Peninsula: 

Alaska Division of Geological and Geophysical Surveys 

Open-File ReportAOF-26, 18 p. 

Martin, G. C., 1925, The outlook for petroleum near Chignik: 

U.S. Geological Survey Bulletin 773, p. 209-213. 

*-1926, The Mesozoic stratigraphy of Alaska: U.S. Geological Survey Bulletin 776, 493 p. 

McLean, Hugh, 1977, Organic geochemistry, lithology, and 

paleontology of Tertiary and Mesozoic rocks from wells on 

the Alaska Peninsula: U.S. Geological Survey Open-File 

Report 77-813, 68 p. 

Miller, T. P., and Smith, R. L., 1977, Spectacular m~bility of 

ash flows around Aniakchak and Fisher calderas, Alaska: 

Geology, v. 5, p. 173-176. 

Pickthorne, W. J., Yount, M. E., Cooley, E. F., O'Leary, R. 

M., Detra, D. E., and Ito, Gail, 1979, Sample location map 

and analytical data for rock samples collected in 1978, 

Chignik and. Sutwik Island quadrangles, Alaska: U.S. 

Geological Survey Open-File Report 79-1506, scale 

1:250,000. 

*Smith, W. R., 1924, Aniakchak Crater, Alaska Peninsula: 

U.S. Geological Survey Professional Paper 132-J, p. 

J139-J145. 

*Smith, W. R., and Baker, A. A., 1924, The Cold Bay-Chignik 

district, Alaska: U.S. Geological Survey Bulletin 755, p. 

151-218. 

*Tripp, R. B., and Detra, D. E., 1980, Maps showing 

mineralogical data of selected minerals for the nonmagnetic heavy-mineral concentrates of stream sediments in the Chignik and Sutwik Island quadrangles, 

Alaska: U.S. Geological Survey Miscellaneous Field 

Studies Map MF-1053-I, 2 sheets, scale 1:250,000. 

United States Geological Survey, 1978a, Aeromagnetic map 

of Chignik and Sutwik Island quadrangles, Alaska: U.S. 

Geological Survey Open-File Report 78-262, scale 

1:250,000. 

-1978b, Aeromagnetic maps of the Chignik and Sutwik Is· 

land quadrangles, Alaska: U.S. Geological Survey OpenFile Report 78-263, 11 sheets, scale 1:63,360. 

*Waring, G. A., 1917, Mineral springs of Alaska, with a chapter on the chemical character of some surface waters of 

Alaska, by R. B. Dole and A. A. Chambers: U.S. Geological Survey Water-Supply Paper 418, 118 p. 

Wilson, F. H., 1978, Map showing preliminary results ofK-Ar 

studies in the Chignik and Sutwik Island quadrangles, 

Alaska: U.S. Geological Survey Open-File Report 78· 

1064. 

-1980, Late Mesozoic and Cenozoic tectonics and the age 

of porphyry copper prospects; Chignik and Sutwik Island 

quadrangles, Alaska, Hanover, Dartmouth College, Ph.D. 

thesis, 178 p. 

Wilson, F. H., Detterman, R. L., and Silberman, M. L., 1978, 

New ages on intrusive rocks and altered zones on the 

Alaska Peninsula, in Johnson, K. M., ed., The United 

States Geological Survey in Alaska: Accomplishments 

during 1977: U.S. Geological Survey Circular 772-B, p. 

B63-B65. 

Wilson, F. H., Gaum, W. C., and Herzon, P. L., 1981, Map 

and tables showing geochronology and whole rock 

chemistry, Chignik and Sutwik Island quadrangles, 

Alaska: U.S. Geological Survey Miscellaneous Field 

Studies Map MF-1053-M, scale 1:250,000 (in press). 

Yount, M. E., Cooley, E. F., and O'Leary, R. M., 1978, Sample location map, analytical data, and statistical summary 

of analyses of rock samples, Chignik and Sutwik Island 

quadrangles, Alaska: U.S. Geological Survey Open-File 

Report 78-557, scale 1:250,000. 

Part 2. General References (Principally references of regional 

scope in which the Chignik and Sutwik Island quadrangles are incidental to the main theme of the paper.) 

Alaska Division of Geological and Geophysical Surveys, 1974, 

Annual Report 1973: Anchorage, Alaska, 59 p. 

Alaska Division of Geological Survey, 1970, Report for the 

year 1970: College, Alaska, 86 p. 

-1972, Annual report 1971: Anchorage, Alaska, 109 p. 

Alaska Division of Mines and Minerals, 1965, Report for the 

year 1965: Juneau, Alaska, 99 p. 

Alaskan Geology Branch, U.S. Geological Survey, 1972, The 

status of mineral resource information on the major land 

withdrawals of the Alaska Native Claims Settlement Act 

of 1971: U.S. Geological Survey Open-File Report 72-394, 

164 p. 

Armstrong, R. L., Harakal, J. E., and Hollister, V. F., 1976, 

Age determinations of late Cenozoic porphyry copper deposits of the American Cordillera: Institute of Mining and 

Metallurgy Transactions, Section B, v. 85, p. 239-244. 

Atwood, W. W., 1909, Mineral resources of southwestern 

Alaska: U.S. Geological Survey Bulletin 379-C, p. 

108-152. 

*Barnes, D. F., 1967, Four preliminary gravity maps of parts 

of Alaska: U.S. Geological Survey Open-File Report 

67-10,5 p. 

*-1977, Bouguer gravity map of Alaska: U.S. Geological 

Survey Geophysical Investigations Map GP-913, scale 

1:2,500,000. 

Barnes, F. F., 1967, Coal resources of Alaska: U.S. Geological 

Survey Bulletin 1242-B, p. B1-B36. 

Becker, G. F., 1898, Reconnaissance of the gold fields of 

southern Alaska, with some notes on general geology: 

U.S. Geological Survey 18th Annual Report, Part 3, p. 

1-86. 

*Beckinsale, R. D., and Gale, N. N., 1969, A reafpraisal of the 

decay constants and branching ratio of 1 K: Earth and 

Planetary Science.Letters, v. 6, p. 239-294. 

14 

Beikman, H. M., 1975, Preliminary geologic map of the 

Alaska Peninsula and Aleutian Islands: U.S. Geological 

Survey Miscellaneous Field Studies Map MF-674, 2 

sheets, scale 1:1,000,000. 

Berg, H. C., and Cobb, E. H., 1967, Metalliferous lode de-
posits of Alaska: U.S. Geological Survey Bulletin 1246, 

254 p. 

Brockway, Ron, Chairman, Bristol Bay Stratigraphic Committee, 1975, Bristol Bay region, stratigraphic correlation 

section, southwest Aluka: The Alaska Geologic Society. 

Brooks, A. H., 1902, The coal resources of Alaska: U.S. 

Geological Survey Annual Report. 22d, 3, p. 515-571. 

--1906, The geography and geology of Alaska, a summary 

of existing knowledge, with a section on Climate by Cleveland Abbe, Jr., and A topographic map and description 

thereof, by R. U. Goode: U.S. Geological Survey Professional Paper 45, 327 p. · 

-1908, The mining industry in 1907: U.S. Geological Survey Bulletin 345, p. 30-53. 

- 1909, Mineral resources of Alaska, in U .8. Geological 

Survey, Papers on the conservation of mineral resources 

(reprinted from report of the National Conservation 

Commission, February, 1909): U.S. Geological Survey 

Bulletin 394, p. 172-207. 

-1910, Alaska coal and its utilization: U.S. Geological Survey Bulletin 442, p. 47-100. 

-1912, The mining industry in 1911: U.S. Geological Survey Bulletin 520, p. 17-44. 

-1921, The future of Alaska mining: U.S. Geological Survey Bulletin 714, p. 5-57. 

-1923, The Alaskan mining industry in 1921: U.S. Geological Survey Bulletin 739, p. 1-44. 

*Bruns, T. R., and von Huene, Roland, 1977, Sedimentary basins of the Shumagin shelf, western Gulf of Alaska: Houston, Offshore Technology Conference, 9th, p. 41-45. 

Capps, S. R., 1934, Notes on the geology of the Alaska Peninsula and Aleutian Islands: U.S. Geologieal Survey Bulletin 

857-D, p. 141-153. 

Coats, R. R., 1950, Volcanic activity in the Aleutian arc: U.S. 

Geological Survey Bulletin, 974-B, p. 35-49. 

Cobb, E.H., Wanek, A. A., Grantz, Arthur, and Carter, Claire, 

1968: Summary report on the geology and mineral resources of the Bering Sea, Bogoslof, Simeonof, Semidi, 

Tuxedni, St. Lazaria, Hazy Islands, and Forrester Island 

National Wildlife Refuges, Alaska: U.S. Geological Survey 

Bulletin 1260-K, p. K1-K28. 

Cobb, E. H., 1973, Placer deposits of Alaska: U.S. Geological 

Survey Bulletin 1374, 213 p. 

*Dalrymple, G. B., and Lanphere, M. A., 1969, Potassiumargon dating-Principles, techniques and applications to 

geochronology: San Francisco, W. H. Freeman, 258 p. 

*DeLong, S. E., Fox, P. J., and McDowell, F. W., 1978, Subduction of the Kula Ridge at the Aleutian Trench: Geological Society of America Bulletin, v. 89, p. 83-95. 

Demenistskaya, R. M., and Belyaevsky, N. A., 1969, The relation between the Earth's crust, surface relief, and gravity 

field in the U.S.S.R., in Hart, P. J., ed., The Earth's crust 

and upper mantle: American Geophysical Union Monograph 13, p. 312-319. 

Dickinson, W. R., 1974, Sedimentation within and beside ancient and modern magmatic arcs, in Dott, R. G., Jr., and 

Shaver, R. H., eds., Modern and ancient geosynclinal 

sedimentation: Society of Economic Paleontologists and 

Mineralogists Special Publication 19, p. 230-239. 

*Dow, W. G., 1977, Kerogen studies and geologic interpretations: Geochemical Exploration, v. 7, p. 79·99. 

*Engels, J. C., and lngamells, C. 0., 1970, Effect of sample 

inhomogeneity in K-Ar dating: Geochimica et CosmochimicaActa, v. 34, p. 1007-1017. 

*Garner, E. L., Murphy, T. J., Gramlich, J. W., Paulson, P. J., 

and Barnes, I. L., 1975, Absolute isotopic abundance 

ratios and the atomic weight of a reference sample of 

potassium: Journal of Research, National Bureau of 

Standards - A. Physics and Chemistry, v. 79A, p. 

713-725. 

•Gasching, J. C., 1980, Development of uranium exploration 

models for the Prospector Consultant System: Final Report, Stanford Research Institute, Project 7857, SRI In· 

ternational, Menlo Park, Ca. 

Grewingk, Constantin, 1850, Beitrag zur Kenntnws der oro· 

graphischen und 1eognoetischen Beschaffenheit der 

Nordwest Kiiste Amerikas mit den anliegen Inseln: V erh· 

andlungen der Russisch-Kaiserlichen Min. Geseel, zu St. 

Petersburg, 1848-1849,p.76-424. 

•Grimes, D. J., and Marranzino, A. P., 1968, Direct-current 

arc and alternating-current spark emission spectrographic field methods for the semiquantitative analy1is of 

geologic materials: U.S. Geological Survey Circular 591, 

6p. 

Hollick, Arthur, 1930, The Upper Cretaceous floras of 

Alaska, with a description of the plant-bearing beds, by 

G. C. Martin: U .8. Geological Survey Professional Paper 

159, 123 p. 

-1936, The TertiarY- floras of Alaska, with a chapter on The 

geology of the Tertiary deposits, by P. 8. Smith: U.S. 

Geological Survey Professional Paper 182, 185 p. 

Holloway, C. D., 1977, Map showing coal fields and distribu· 

tion of coal- bearing rocks in the western part of southern 

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

77-169-1, scale 1:1,000,000. 

Imlay, R. W., 1975, Stratigraphic dittribution and zonation of 

Jurassic (Callovian) ammonites in southern Alaska: U.S. 

Geological Survey Professional Paper 836, 28 p. 

Imlay, R. W., and Detterman, R. L., 1973, Jurassic 

paleobiogeography of Alaska: U.S. Geological Survey Professional Paper 801, 34 p. 

Knowlton, F. H., 1898, A catalogue of the Cretaceous and 

Tertiary plants of North America: U .8. Geological Survey 

Bulletin 152, 247 p. 

MacKevett, E. M., Jr., and Holloway, C. D., 1977, Map showing metalliferous mineral deposits in the western part of 

southern Alaska: U.S. Geological Survey Open-File Report 77-169-F, scale 1:1,000,000. 

-1977, Table describing metalliferous mineral deposits in 

the western part of southern Alaska: U.S. Geological SurveyOpen-FileReport 77-169-F, 39 p. 

15 

Mancini, E. A., Deeter, T. M., and Wingate, F. H., 1978, 

Upper Cretaceous arc-trench gap sedimentation on the 

Alaska Peninsula: Geology, v. 6, p. 437-439. 

Marlow, M.S., Alpha, T. R., Scholl, D. W., and Buffington, E. 

C., 1975, Bering Sea shelf, Alaska: U.S. Geological Survey Open-File Report 75-1, 2 sheets. 

Martin, G. C., 1907, The Alaska coal fields: U.S. Geological 

Survey Bulletin 314, p. 40-46. 

-1921, Preliminary report on petroleum in Alaska: U.S. 

Geological Survey Bulletin 719,83 p .. 

McGee, D. L., 1972, Gulf of Alaska petroleum seeps: Alaska 

Division of Geological and Geophysical Surveys Open-File 

ReportAOF-32, 7 p. 

Miller, D. J., Payne, T. G., and Gryc, George, 1959, GeoloiJ 

of possible petroleum provinces in Alaska, with an Anno· 

tated bibliography by E. H. Cobb: U.S. Geological Survey 

Bulletin 1094, 131 p. 

Miller, T. P., 1973, Distribution and chemical analyses of 

thermal springs in Alaska: U.S. Geological Survey Open· 

File Report 73-187, scale 1:2,500,000. 

Moore, J. C., 1973, Cretaceous continental margin sedimen· 
tation, southwestern Alaska: Geological Society of 

America Bulletin, v. 84, p. 595-614. 

Moxham, R. M., 1951, Pumice deposits in the Alaska 

Peninsula-Cook Inlet region, Alaska: U.S. Geological Survey Open-File Report 52-103,21 p. 

*Packer, D.R., and Stone, D. B., 1974, Paleomagnetism of 

Jurassic rocks from southwestern Alaska and their implication: Canadian Journal of Earth Sciences, v. 11, p. 

976-997. 

*Racklay, R. I., 1976, Origin of western states-type uranium 

mineralization, in Wolf, K. H., ed., Handbook of 

stratabound and strataform deposits: Amsterdam, 

Elsevier, p. 89-152. 

Smith, P. S., 1939, Areal geology of Alaska: U.S. Geological 

Survey Professional Paper 192, 100 p. 

*Smith, R. L., and Shaw, H. R., 1975, Igneous-related geothermal systems, in White, D. E., and Williams, D. L., 

eds., Assesment of geothermal resources of the United 

States-1975: U.S. Geological Survey Circular 726, p. 

58-83. 

*Stone, D. B., and Packer, D. R., 1979, Paleomagnetic data 

from the Alaska Peninsula: Geological Society of America 

Bulletin, Part 1, v. 90, p. 545-560. 

Stone, R. W., 1905, Coal resources of southwestern Alaska: 

U.S. Geological Survey Bulletin 259, p. 151-171. 

*Streckeisen, Albert, 1976, To each plutonic rock its proper 

name: Earth- Science Reviews, v. 12, p. 1-33. 

--1979, Classification and nomenclature of volcanic rocks, 

lamprophyres, carbonatites, and melilitic rock: Recommendations and suggestions of the lUGS Subcomission on 

the Systematics of Igneous Rocks: Geology, v. 7, p. 

331-335. 

U.S. Bureau of Mines, 1946, Analyses of Alaska coals, with a 

section on Coal fields of Alaska, by G. 0. Gates: U.S. 

Bureau of Mines Technical Paper 682, 114 p. 

16 

U.S. Geological Survey, 1899, Maps and descriptions of 

routes of exploration in Alaska in 1898, with general information concerning the Territory: U.S. Geological Survey Special Publication, 138 p. 

Von Huene, Roland, Smith, Rodney, Hampton, Monty, 

Moore, George, and Dolton, Gordon, 1975, A preliminary 

summary of petroleum potential, environmental geology, 

and the technology, time-frame, and infrastructure for 

exploration and development of the western Gulf of 

Alaska: U.S. Geological Survey Open-File Report 75-536, 

54 p. 

Warfield, R. S., 1967, Resume of information on Alaskan 

bituminous coals with particular emphasis on coking 

characteristics: U.S. Bureau of Mines Open-File Report 

11-67, 20 p. 

*Ward, F. N., Nakagawa, H. M., Harms, T. F., and Van Sickle, 

G. H., 1969, Atomic-absorption methods of analysis useful in geochemical exploration: U.S. Geological Survey 

Bulletin 1289, 45 p. 

Wedow, Helmuth, Jr., White, M. G., and Moxham, R. M., 

1952, Interim report on an appraisal of the uranium possibilities of Alaska: U.S. Geological Survey Open-File Report 52-165, 123 p. 

Wolfe, J. A., 1972, An interpretation of Alaskan Tertiary 

floras, in Graham, A., ed., Floristics and paleofloristics of 

Asia and eastern North America: Amsterdam, Elsevier, p. 

201-233. 

Wolfe, J. A., Hopkins, D. M., and Leopold, E. B., 1966, Tertiary stratigraphy and paleobotany of the Cook Inlet region, Alaska: U.S. Geological Survey Professional Paper 

398-A, p. A1-A29. 

Wollard, G. P., and Strange, W. E., 1962, Gravity anomalies 

and crust of the Earth in the Pacific Basin, in MacDonald, 

G. A., and Kuno, Hisashi, eds., The crust of the Pacific 

Basin: American Geophysical Union Geophysical Monograph 6, p. 60-80. 

GPO 789-036/17