U.S. GEOLOGICAL SURVEY CIRCULAR 1106 

Mineral-Resource Assessments in AlaskaBackground Information to Accompany 

Maps and Reports about the Geology and 

Undiscovered-Mineral-Resource Potential of the 

Mount Katmai Quadrangle and Adjacent Parts of the 

Naknek and Afognak Quadrangles, Alaska Peninsula 
AVAILABILITY OF BOOKS AND MAPS OF THE U.S. GEOLOGICAL SURVEY 

Instructions on ordering publications of the U.S. Geological Survey, along with prices of the last offerings, are given 

in the current-year issues of the monthly catalog "New Publications of the U.S. Geological Survey." Prices of available U.S. 

Geological Survey publications released prior to the current year are listed in the most recent annual "Price and Availability 

List." Publications that may be listed in various U.S. Geological Survey catalogs (see back inside cover) but not listed in 

the most recent annual "Price and Availability List" may be no longer available. 

Reports released through the NTIS may be obtained by writing to the National Technical Information Service, U.S. 

Department of Commerce, Springfield, VA 22161; please include NTIS report number with inquiry. 

Order U.S. Geological Survey publications by mail or over the counter from the offices given below. 

BY MAIL 

Books 

Professional Papers, Bulletins, Water-Supply Papers, Techniques of Water-Resources Investigations, Circulars, publications 

of general interest (such as leaflets, pamphlets, booklets), single 

copies of Earthquakes & Volcanoes, Preliminary Determination of 

Epicenters, and some miscellaneous reports, including some of the 

foregoing series that have gone out of print at the Superintendent 

of Documents, are obtainable by mail from 

U.S. Geological Survey, Map Distribution 

Box 25286, MS 306, Federal Center 

Denver, CO 80225 

Subscriptions to periodicals (Earthquakes & Volcanoes and 

Preliminary Determination of Epicenters) can be obtained ONLY 

from the 

Superintendent of Documents 

Government Printing Office 

Washington, D.C. 20402 

(Check or money order must be payable to Superintendent 

of Documents.) 

Maps 

For maps, address mail orders to 

U.S. Geological Survey, Map Distribution 

Box 25286, Bldg. 810, Federal Center 

Denver, CO 80225 

Residents of Alaska may order maps from 

U.S. Geological Survey, Earth Science Information Center 

101 Twelfth Ave. -Box 12 

Fairbanks, AK 99701 

OVER THE COUNTER 

Books and Maps 

Books and maps of the U.S. Geological Survey are 

available over the counter at the following U.S. Geological Survey 

offices, all of which are authorized agents of the Superintendent of 

Documents: 

• ANCHORAGE, Alaska-Rm. 101, 4230 University Dr. 

• LAKEWOOD, Colorado-Federal Center, Bldg. 810 

• MENLO PARK, California-Bldg. 3, Rm. 3128, 345 

Middlefield Rd. 

• RESTON, Virginia-USGS National Center, Rm. 1C402, 

12201 Sunrise Valley Dr. 

• SALT LAKE CITY, Utah-Federal-Bldg., Rm. 8105, 125 

South State St. 

• SPOKANE, Washington-U.S. Post Office Bldg., Rm. 

135, West 904 Riverside Ave. 

• WASHINGTON, D.C.-Main Interior Bldg., Rm. 2650, 

18th and C Sts., NW. 

Maps Only 

Maps may be purchased over the counter at the following 

U.S. Geological Survey offices: 

• FAIRBANKS, Alaska-New Federal Bldg., 101 Twelfth 

Ave. 

• ROLLA, Missouri-1400 Independence Rd. 

• STENNIS SPACE CENTER, Mississippi-Bldg. 3101 
Mineral-Resource Assessments in AlaskaBackground Information to Accompany 

Maps and Reports about the Geology and 

Undiscovered-Mineral-Resource Potential of the 

Mount Katmai Quadrangle and Adjacent Parts of the 

Naknek and Afognak Quadrangles, Alaska Peninsula 

By J.R. Riehle, S.E. Church, R.L. Detterman, and J.W. Miller 

U.S. GEOLOGICAL SURVEY CIRCULAR 1106 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1994 
U.S. DEPARTMENT OF THE INTERIOR 

BRUCE BABBITT, Secretary 

U.S. GEOLOGICAL SURVEY 

GORDON P. EATON, Director 

For sale by U.S. Geological Survey, Map Distribution 

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. 

Published in the Eastern Region, Reston, Va. 

Manuscript approved for publication February 18, 1994. 

Library of Congress Cataloging in Publication Data 

Mineral-resource assessments in Alaska : background information to accompany maps 

and reports about the geology and undiscovered-mineral-resource potential of the 

Mount Katmai quadrangle and adjacent parts of the Naknek and Afognak 

quadrangles, Alaska Peninsula I J.R. Riehle ... [et al.]. 

p. em. - (U.S. Geological Survey circular; 1106) 

Includes bibliographical references (p. ). 

Supt. of Docs. no.: I 19.4/2: 1106 

1. Mines and mineral resources-Alaska-Katmai, Mount, Region. 2. Katmai National 

Park and Preserve (Alaska) I. Riehle, J.R. II. Series. 

TN24.A4M466 1995 

553' .09798'4-dc20 94-10108 

CIP 
CONTENTS 

Abstract........................................................................................... 1 

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 

Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 

Mineral-Resource Assessments......................................................... 3 

Definitions and Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 

Recent Mineral Assessments in Alaska . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 

Geographic and Physiograhpic Setting of the Katmai Study Area . . . . . . . . . . . . . . . 5 

Geologic Investigations in the Katmai Region . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 

Previous Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 

Present Study.............................................................................. 6 

Map I-2032: Quaternary geologic map of the Mount Katmai quadrangle 

and adjacent parts of the Naknek and Afognak quadrangles, 

Alaska.................................................................... 6 

Map I-2204: Geologic map of the Mount Katmai quadrangle and 

adjacent parts of the Naknek and Afognak quadrangles, 

Alaska.................................................................... 6 

Open-File Report 86-586: Analytical results and sample locality map 

of stream-sediment and heavy-mineral-concentrate samples 

from the Mount Katmai quadrangle, and portions of the 

Naknek, Afognak, and Iliamna quadrangles, Alaska............. 8 

Open-File Report 87-615: Mineralogy and sample-locality map of the 

nonmagnetic heavy-mineral-concentrate samples from the 

Mount Katmai quadrangle and portions of the Naknek, 

Afognak, and Iliamna quadrangles, Alaska........................ 8 

Open-File Report 88-422: Analytical data and sample locality map for 

aqua-regia leachates of stream sediments analyzed by ICP 

from the Mount Katmai quadrangle, and portions of the 

Naknek, Afognak, and Iliamna quadrangles, Alaska............. 8 

Open-File Report 89-570: Sample locality maps, analytical data, and 

statistical summary of analyses of rock samples from the 

Mount Katmai quadrangle and adjacent portions of the Naknek 

and Afognak quadrangles, Alaska................................... 8 

MF-2021-A: Geochemical map showing the distribution of selected 

elements determined in stream sediments from the Mount 

Katmai and portions of the Afognak and Naknek quadrangles, 

Alaska.................................................................... 9 

MF-2021-B: Geochemical maps showing the distribution of selected 

leachable metals determined by ICP in stream sediments from 

the Mount Katmai and portions of the Afognak and Naknek 

quadrangles, Alaska.................................................... 9 

MF-2021-C: Geochemical map showing the distribution of selected 

elements determined in nonmagnetic heavy-mineral concentrates 

from the Mount Katmai and portions of the Afognak and 

Naknek quadrangles, Alaska. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 

MF-2021-D: Mineralogic map showing the distribution of selected 

minerals identified in nonmagnetic heavy-mineral concentrates 

from the Mount Katmai and portions of the Afognak and 

Naknek quadrangles, Alaska. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 

III 
IV CONTENTS 

Bulletin 2020: Interpretation of exploration geochemical data from the 

Mount Katmai quadrangle and adjoining parts of the Afognak 

and Naknek quadrangles, Alaska . . . . . . . . . .. . . . . . . . . .. . . . . . . . . . . . . . . . 9 

MF-2021-E: Map and table showing K-Ar ages from the Mount Katmai 

and adjacent parts of the Naknek and Afognak quadrangles, 

Alaska.................................................................... 10 

MF-2021-F: Mineral and energy resource assessment maps of the 

Mount Katmai, Naknek, and western Afognak quadrangles, 

Alaska.................................................................... 10 

MF-2021-G: Macrofossil locality map, checklists, and pre-Quaternary 

stratigraphic sections of the Mount Katmai quadrangle and 

adjacent parts of the Naknek and Afognak quadrangles, 

Alaska.................................................................... 11 

References Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 

FIGURES 

1. Map showing location of Mount Katmai study area on the eastern Alaska Peninsula.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 

2. Map showing physiographic features and tracts having favorable potential for mineral deposits, Mount 

Katmai study area... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 

TABLE 

1. Geologic, geochemical, and mineral-resource publications of the Mount Katmai study................................. 4 

Multiply 

meter (m) 

kilometer (km) 

square kilometer (km2

) 

METRIC CONVERSION FACTORS 

By 

Length 

3.281 

0.621 4 

Area 

0.386 1 

To obtain 

foot 

mile 
CONTENTS v 

GLOSSARY OF TERMS 

For a complete glossary of geologic terms, see the 

Glossary of Geology (Bates and Jackson, 1980). 

Airfall. Volcanic particles, typically sand-sized ash but 

including coarser and finer sizes, that are erupted into 

the air and fall therefrom; also the resulting deposit. 

Andesite. A compositional term for a volcanic rock 

having a silica content (Si02) of between 56 percent 

and 63 percent by weight. 

Ash-flow tuff. A volcanic rock that formed from a 

flowing mass of erupted gas and sand-sized particles of 

glass, rock fragments, and minerals. 

Basalt. A compositional term for a volcanic rock having 

a silica content (Si02 ) of less than 53 percent by 

weight. 

Batholith. A mass of intrusive igneous rock, underlying 

hundreds to thousands of square kilometers, typically 

intruded as a series of individual magma masses 

(plutons) that have a variety of compositions. 

Conglomerate. A sedimentary rock formed of gravel, 

cobbles, and boulders. 

Dacite. A compositional term for a volcanic rock having 

a silica content (Si02) of between 63 percent and 68 

percent by weight. 

Diabase. A dark-colored, intrusive igneous rock having a 

low silica content similar to that of basalt or andesite. 

Dike. An intrusive igneous rock in which the form of the 

intruded magma is like a wall that cuts across layering 

in the wall rocks. 

Dome. A volcanic rock consisting of lava that mounded 

above its vent because it was too viscous to flow. 

Fault. A break in the Earth's crust across which the rocks 

have moved relative to one another. 

Flow. The movement of erupted lava laterally on the 

ground surface; also refers to the resulting rock. 

Fumarole. A vent for gases and vapors. 

Gabbro. A dark-colored intrusive rock; the extrusive 

(volcanic) equivalent is basalt. 

Gneiss. A metamorphic rock consisting of alternating 

bands of dark and light minerals. 

Gossan. A mass of rock visually identifiable by a reddish 

color resulting from oxidation of iron; forms by weathering of rocks containing abundant pyrite, typically 

secondary. 

Granite. An intrusive igneous rock consisting mainly of 

quartz and alkali feldspar. 

Granodiorite. An intrusive igneous rock having as much 

quartz as does granite, and an alkali feldspar content 

between that of granite and tonalite. 

Greenschist. A category of metamorphism that occurs at 

low to moderate temperatures (300-500 °C) and pressures (less than 20 km deep); metamorphic minerals 

characteristic of this category include several that are 

green. 

Hydrothermal. An adjective referring to naturally occurring, heated water that contains dissolved solids and 

gases; heat sources are commonly either recently 

intruded magma or deep crustal rocks. 

Indurated. Refers to a sediment hardened by pressure, 

heat, or cement into a rock. 

Intrusion. The process in which magma moves chiefly 

vertically into a host rock where it solidifies by 

cooling; the resulting rock is an intrusive rock. 

Limestone. A sedimentary rock that consists essentially 

of the mineral calcite, formed either of shell fragments 

or, less commonly, by chemical precipitation. 

Metamorphic rock. A rock in which the original mineral 

grains have recrystallized to form new mineral grains, 

or new minerals, due to application of heat and (or) 

pressure. 

Moraine. Any nonsorted glacial deposit, typically consisting of mixed silt, sand, and boulders; also refers to 

the landform resulting from the deposit. 

Porphyritic. An adjective applied to volcanic or intrusive 

rocks having some mineral grains that are distinctly 

larger than others; the implication is that an early 

period of slow cooling (coarse grains) was followed by 

sudden rise of the magma to shallow crustal levels and 

chilling (fine grains). 

Pumice. Volcanic glass that was highly inflated at the 

time of eruption by abundant gas pockets (bubbles). 

Pyrite. Iron sulfide; not an ore-forming mineral but may 

be evidence of mineralizing fluids and so may be 

associated with ore minerals. 
VI CONTENTS 

Quartz diorite. An intrusive igneous rock having little 

quartz or alkali feldspar, and a high content of plagioclase feldspar and dark accessory minerals. 

Quartz monzodiorite. An intrusive igneous rock having 

contents of quartz and alkali feldspar that are between 

those of granite and quartz diorite. 

Quartzite. A metamorphic rock consisting essentially of 

quartz grains; the original rock was typically a quartz 

sandstone. 

Reverse fault. A steeply dipping fault along which the 

rocks above the fault have moved up relative to those 

below. 

Rhyolite. A compositional term for a volcanic rock having a silica content (Si02) of between 68 percent and 

77 percent by weight. 

Silicification. The process of adding silica to a rock by 

chemical precipitation from fluids. 

Sill. An intrusive igneous rock having a tabular form, of 

which the two long dimensions are parallel to bedding 

in the adjacent wall rocks. 

Stratovolcano. A volcano, typically cone shaped and 

more than 300 m above its base, consisting of alternating layers (strata) of lava, cinders, and ash. 

Subduction. A process of plate tectonics in which one 

crustal plate, commonly but not necessarily an oceanic 

plate, slides beneath another plate; the site of contact 

between the plates is usually a physiographic trench, 

and the region behind the trench is one of elevated 

seismicity and active volcanism caused by the downgoing plate. 

Tonalite. An intrusive igneous rock having the same 

content of quartz as does granite, but less alkali 

feldspar than does granodiorite. 

Vein. A fracture in a rock filled by secondary minerals, 

typically formed by chemical precipitation from hydrothermal fluids; such deposits commonly appear veinlike when viewed on rock faces. 

Volcanic arc. A belt of aligned volcanoes that follows an 

arcuate trace in map view; volcanic arcs are typically 

formed above subducting plates. 

Wall rock. Preexisting rock that hosts a younger rock 

such as a magmatic intrusion or a vein. 
Mineral-Resource Assessments in AlaskaBackground Information to Accompany 

Maps and Reports about the Geology and 

Undiscovered-Mineral-Resource Potential of the 

Mount Katmai Quadrangle and Adjacent Parts of the 

Naknek and Afognak Quadrangles, Alaska Peninsula 

By J.R. Riehle, S.E. Church, R.L. Detterman, and J.W. Miller 

ABSTRACT 

Geologic and geochemical field studies were carried 

out from 1983 to 1987 in the Mount Katmai 1 oX 2° 

quadrangle and adjoining region, at the northeast end of the 

Alaska Peninsula. The region is nearly entirely within 

Katmai National Park and Preserve and has had almost no 

mineral production, so prior to this study there were few 

data by which to assess the mineral potential of the region. 

This report describes the folio of publications that have 

resulted from the study: geologic maps, geochemical 

results, fossil identifications, radiometric rock ages, and an 

assessment of the undiscovered-mineral-resource potential 

of the region. 

The Katmai region is inferred to potentially have three 

types of undiscovered mineral deposits: porphyry copper 

(molybdenum), precious-metal vein, and hot-springs gold. 

These deposit types occur elsewhere on the Alaska Peninsula in similar geologic units. Evidence suggesting their 

occurrence in the Katmai region is the presence of trace 

amounts of metals typically associated with these kinds of 

deposits in bedrock of certain tracts and in sediments of 

streams draining those tracts. Magma to provide heat, 

fractures to provide pathways for mineralizing fluids, and 

altered rock are required by genetic models of these deposit 

types. Such features do occur in the Katmai tracts. Confirmation of any mineral deposit in the Katmai region requires 

detailed followup sampling and acquisition of subsurface 

information, which is beyond the scope of this study. 

However, producing porphyry deposits are unknown elsewhere on the Alaska Peninsula in similar rocks, so if any 

such deposits occur in the Katmai region, they are likely to 

be few in number. Conversely, vein deposits are typically 

small in size so there may be several of such deposits. 

The properties and thermal history of the sedimentary 

rocks that could serve as reservoirs for oil or gas are 

unfavorable in adjacent regions. Thus the potential of the 

Katmai region for producible quantities of fossil fuels is 

low. In theory the region has shallow concentrations of 

geothermal fluids, but specific evidence for their presence is 

obscured by heavy precipitation and cold young rocks or 

deposits. Small volumes of coal occur at tidewater sites on 

the Pacific coast. 

INTRODUCTION 

BACKGROUND 

This report describes a set of maps and reports about 

the geology, geochemistry, and mineral resources of the 

Mount Katmai quadrangle and adjacent portions of the 

Naknek and Afognak quadrangles on the Alaska Peninsula. 

The reports, published under the auspices of the former 

Alaska Mineral Resources Assessment Program, provide 

information for decisions about landownership, for landuse planning, and for policymaking concerning the national 

mineral endowment. Such reports should be useful to State 

and Federal agencies, to private landowners, and to the 

mineral industry in Alaska. 

The study area occupies 15,000 km2 that extend 

east-west across the Alaska Peninsula at its northeast end 

(fig. 1). Most of the study area is within Katmai National 

Park and Preserve (fig. 2); a small area at the south margin 

is within Becharof National Wildlife Refuge. Mineral 

production in a national park, part of which is also wilderness, may be unlikely. Regardless, the study has three main 

benefits. First, geologic trends and rock units in adjacent 

areas were either traced through the study area or were 
2 MINERAL RESOURCE ASSESSMENTS IN ALASKA 

15156'~--------------------~15~4° ____ ~~~~ 60° r- ILIAMNA 

Area of study 

Valley of 10,000 

Smokes <v 

"?' 

«-

~ 

0 

B 

QUADRANGLE NAME 

0 

Inlet 

0 10 20 30 40 50 MILES 

10 20 30 40 50 KILOMETERS 

Figure 1. Location of Mount Katmai study area on the eastern Alaska Peninsula. 

shown not to continue across the area. Such information 

aids in interpretation of the geologic history of the adjacent 

areas where mineral extraction is more feasible. Second, 

new insights into the geologic processes responsible for 

mineralization of similar rock units elsewhere on the Alaska 

Peninsula have been gained by their study in the Katmai 

area, regardless of whether any Katmai mineral deposits are 

ever exploited. And third, better understanding of the 

mineral resources of the Katmai area will permit more 

informed decisionmaking about the national mineral 

endowment. 

Fieldwork was carried out from 1983 through 1987 by 

a team of earth scientists having a range of expertise. 

Individuals collaborated to produce specialized maps and 

topical reports. The maps (table 1) focus on bedrock 

geology, fossils, surficial geology, potassium-argon geochronology (rock ages), and the distribution of elements and 

minerals in stream-sediment and bedrock geochemical samples. The reports (table 1) focus on interpretation of the 

exploration geochemical data and its implications for the 

mineral potential of the study area. 

Geologic information indicates the kinds of geologic 

processes that have occurred in the study area and which 

tracts could have certain kinds of mineral deposits. Geochemical studies provide specific evidence of mineralization. In order to assess the mineral potential, the available 
INTRODUCTION 3 

158° 156° 

Area of study 

154° 

Cook 

Inlet 

Ku kaklek Lake 

~B tle Na nwhyenuk - · - · - · , ~ e 

_ ... Lake · ........ _\::5 

0 10 20 30 40 50 MILES 

10 20 30 40 50 KILOMETERS 

EXPLANATION 

D Tract judged to have favorable mineral-resource potential 

. ..- Present boundary, Katmai National Park and Preserve 

••• •• 1918 boundary, Katmai National Park and Preserve 

Figure 2. Physiographic features and tracts having favorable potential for mineral deposits, Mount Katmai study area. 

geologic and geochemical data from the study area are 

combined with information from other, geologically similar 

areas that have been more thoroughly explored for minerals. 

The assessment is a professional judgment of the likelihood 

that undiscovered mineral deposits having potential economic value occur in the study area. To confirm the 

occurrence of mineral deposits requires subsurface information, typically acquired by drilling, which is beyond the 

scope of the present study and which has never been carried 

out in the region. Thus the assessment does not specify a 

precise number of undiscovered deposits, nor does it 

consider economic conditions of extraction and sale. 

MINERAL-RESOURCE ASSESSMENTS 

DEFINITIONS AND CONCEPTS 

Basic terms and concepts of mineral-resource assessments are defined in this section. Other geologic terms used 

elsewhere in this report are defined in the glossary. 

A mineral resource is a geologic deposit from which 

useful metallic, nonmetallic, or hydrocarbon material could 

potentially be extracted (Harris, 1984). A deposit is a 

volume of rock that formed during a limited interval of 

geologic time in response to a single set of geologic 

processes. A mineral occurrence is a concentration of a 

mineral that is of scientific or economic interest; a mineral 

deposit is an occurrence that could be economically produced under favorable circumstances (Cox and others, 

1986). Mineral deposits can form at the same time as the 

rock in which they occur (primary mineralization) or they 

can form later (secondary mineralization). 

Economic resources are those known to be economically extractable under specified market conditions (U.S. 

Bureau of Mines and U.S. Geological Survey, 1980). 

Undiscovered resources are the subject of this study and 

are hypothetical without intensive sampling, typically by 

drilling, to prove their vertical extent. An assessment of the 

undiscovered resources of the Katmai region is not, however, just speculation. Rather, it is a professional judgment 
4 MINERAL RESOURCE ASSESSMENTS IN ALASKA 

Table 1. Geologic, geochemical, and mineral-resource publications of the Mount Katmai study. 

[Maps are 1:250,000 scale] 

Map or report no. 

Miscellaneous Investigation 

Map I-2032. 

Miscellaneous Investigation 

Map I-2204. 

Open-File Report 86-586 

Open-File Report 87-615 

Open-File Report 87-422 

Open-File Report 89-570 

Miscellaneous Field Studies 

Map MF-2021-A. 

MF-2021-B 

MF-2021-C 

MF-2021-D 

Bulletin 2020 

MF-2021-E 

MF-2021-F 

MF-2021-G 

Description 

Geologic map of Quaternary rocks and deposits (in color) 

Bedrock geologic map (in color) 

Analytical results and localities of stream-sediment samples and 

heavy-mineral concentrates. 

Mineralogy of nonmagnetic heavy-mineral concentrates from 

stream-sediment samples, and localities. 

ICP analytical results for aqua-regia leachates of streamsediment samples. 

Locality map, analytical results, and statistical summary of bedrock samples. 

Map showing distribution of selected elements in streamsediment samples. 

Maps showing distribution of selected leachable metals in 

stream-sediment samples. 

Map showing distribution of selected elements in nonmagnetic 

heavy-mineral concentrates from stream-sediment samples. 

Map showing distribution of minerals in nonmagnetic heavymineral concentrates from stream-sediment samples. 

Interpretation of bedrock and stream-sediment analytical data in 

terms of mineral-deposit types. 

Map showing potassium-argon ages of rocks 

Maps showing assessment of undiscovered mineral and energy 

resources. 

Map of macrofossil localities and stratigraphic sections 

Author 

Riehle and Detterman, 1993. 

Riehle and others, 1993. 

Bailey and others, 1986. 

Bennett and Church, 1987. 

Ehrlich and others, 1988. 

Riehle and others, 1989. 

Church and others, 1989a. 

Church and Motooka, 1989. 

Church and Arbogast, 1989. 

Church and Bennett, 1989. 

Church and others, in press. 

Shew and Lanphere, 1992. 

Church and others, 1992. 

Miller and others, in press. 

based on mineral occurrences at the ground surface about 

the potential that mineral deposits occur at depth. 

Three kinds of data were newly gathered for the 

Katmai assessment. (1) Geologic mapping permits identification of different geologic terranes and, by analogy with 

better studied areas elsewhere, suggests the types of deposits that are likely to occur in those terranes. (2) Stream 

sediments ideally provide a composite sampling of an entire; 

drainage basin. (3) Samples of mineralized bedrock provide 

direct evidence for the occurrence, and something about the 

nature, of mineralization. Mineralized bedrock was specifically sought throughout the course of fieldwork. Based on 

these kinds of information, small tracts having both permissive and specific evidence of mineralization at the ground 

surface were identified. 

Naknek quadrangle where bedrock is deeply buried beneath 

glacial drift. Moreover, the aeromagnetic data are too 

widely spaced to delineate any but the largest areas of 

magnetically anomalous rock. 

The Katmai study lacks subsurface information and so 

does not rigorously assess the size or number of potential 

deposits. Geophysical data can help to constrain the size of 

favorable host rocks for certain deposit types. In the Katmai· 

region, however, aeromagnetic data (Andreasen and others, 

1963) are the only regionally extensive, geophysical data 

that are available, and these are available only for the 

RECENT MINERAL ASSESSMENTS IN ALASKA 

By 1971, two National laws regarding landownership 

in Alaska had been enacted. The Alaska Statehood Act 

(1958) allowed the State to select about one-quarter ofthe 

landmass for State ownership. The Alaska Native Claims 

Settlement Act (ANCSA; 1971) allowed Alaskan Natives to 

select one-eighth of the State for private ownership and 

further authorized the Secretary of the Interior to withdraw 

another one-quarter for potential inclusion in parks or other 

preservation units. ANCSA required identification of the 

withdrawals by December 1978. Consequently, in 1974 

Congress requested that the U.S. Geological Survey 

(USGS) provide information about the mineral potential of 

the probable withdrawals in time for Congress to use in the 

final decisions. Initially multidisciplinary teams undertook 
GEOLOGIC INVESTIGATIONS IN THE KA TMAI REGION 5 

to produce folios of geologic, geophysical, and geochemical data for selected 1:250,000-scale quadrangles. Quadrangles were selected both for their mineral potential and for 

being likely candidates for withdrawal. In order to meet the 

1978 deadline, however, the approach was modified to 

compilation of existing data, supplemented by limited 

fieldwork, at 1:1,000,000 scale (Singer and Ovenshine 

1979). Results at this scale were completed early in 1978 

(MacKevett and others, 1978). 

The original concept of 1:250,000-scale assessments 

was given new impetus with passage of the Alaska National 

Interest Lands Conservation Act (ANILCA) in 1980. 

ANILCA requirements for more detailed information about 

mineral resources on Federal lands, together with continuing State and Native land selections from the territorial 

landpool, provided the basis for the Alaska Mineral 

Resources Assessment Program (AMRAP). The objective 

of AMRAP was to identify areas in Alaska having mineralresource potential and to quantify that potential as far as 

possible (Grybeck and Berg, 1982). The AMRAP approach 

was to first compile available data, then in selected areas to 

carry out fieldwork by multidisciplinary teams for a period 

of 2 to 4 yr to acquire needed information. Such "Level III" 

studies of 1:250 ,000-scale quadrangles provide information 

that is used to periodically upgrade statewide or regional 

assessments (Levels I or II) as well as to focus on specific 

deposits for followup studies at larger scales (Level IV). 

The Katmai study is such a Level III study. Since 

completion of the Katmai study, USGS assessments of 

mineral resources in Alaska have been carried out as part of 

a national assessment program. 

GEOGRAPHIC AND PHYSIOGRAPIDC SETTING 

OF THE KATMAI STUDY AREA 

The Katmai study area is sited on the Alaska Peninsula 

between 58° and 59° north latitude (figs. 1, 2); its northern 

boundary is at Cape Douglas, and the southern boundary 

transects Becharof Lake. The western and eastern boundaries are at the coasts of Bristol Bay and Shelikof Strait, 

respectively. 

Two physiographic provinces compose the study area: 

the Bristol Bay Lowland province in the west and the 

Aleutian Range province in the east (W ahrhaftig, 1965). 

The Bristol Bay Lowland is characterized by broad coastal 

plains, low topographic relief, numerous bogs and small 

lakes, and low-gradient meandering streams. In contrast, 

the Aleutian Range is capped by active volcanoes. Elevations exceed 2,000 mat volcanoes such as Mount Katmai, 

Mount Mageik, Mount Griggs (Knife Peak), Snowy Mountain, Mount Denison, Fourpeaked Mountain, and Mount 

Douglas. Streams in the Aleutian Range have steep gradients and occupy youthful drainages. Glaciers are present on 

the large peaks; both Hallo Glacier and Fourpeaked Glacier 

extend nearly to sea level on Shelikof Strait. The Valley of 

Ten Thousand Smokes contains thick deposits of volcanic 

ash from the 1912 eruption of Novarupta. 

There are three permanently inhabited communities in 

the study area: King Salmon, Naknek, and South Naknek. 

All three are sited within 30 km of one another, on the 

Naknek River at the west margin of the study area. The only 

other habitations are seasonally occupied lodges on Brooks, 

Kulik, Grosvenor, and Nanwhyenuk (Nonvianuk) Lakes. 

The lodge on Brooks Lake serves as a staging area for 

visitors to the interior of Katmai National Park and Preserve. 

Katmai National Monument was created in 1918 as a 

consequence of the 1912 eruption of Novarupta dome 

(originally erroneously attributed to Mount Katmai). One of 

the purposes of the monument is to preserve the spectacular 

volcanic deposits of the eruption for scientific study and for 

public education about volcanic eruptions. The monument 

initially extended from the head of Kukak Bay southwest to 

Cape Kubugakli and northwest to encompass all of the lliuk 

Arm of Naknek Lake (4,350 km2

; fig. 2) and was closed to 

mineral entry. There are no mining claims or prospects 

within this core area. Additions to the monument were 

made in 1931 (to 10,788 km2

), in 1942, and again in 1969, 

by which time all of Lake Brooks, Naknek Lake, Lake 

Grosvenor, and Lake Colville as well as offshore islands 

were included in the monument. Under the Alaska National 

Interest Lands Classification Act, the name was changed in 

1980 to Katmai National Park and Preserve, and the total 

area was enlarged to 16,764 km2 . Most of this area is also 

designated as wilderness (Katmai National Park and Preserve, written commun., 1992). 

GEOLOGIC INVESTIGATIONS IN THE 

KATMAI REGION 

PREVIOUS STUDIES 

Geologic fieldwork in the Katmai region prior to 1950 

was infrequent and localized. Spurr and Post (1899) traversed the region from Bristol Bay to Katmai Bay in 1898, 

following an early trade route over Katmai Pass; they noted 

a lack of placer gold along their route and attributed it to 

" ... the volcanic region being apparently without much 

mineralization .... " Atwood (1911) reported no known mineral occurrences in the Katmai region as of 1908. The first 

lengthy, documented explorations followed the catastrophic 

eruption of Novarupta dome in 1912. Such explorations, 

summarized by Griggs (1922), focused on the deposits in 

and around the Valley of Ten Thousand Smokes. 

The oldest claim in the Katmai area, filed in 1918, is 

a gold-placer claim on the American River south of Nanwhyenuk Lake (fig. 2). Martin (1920) reported secondhand 
6 MINERAL RESOURCE ASSESSMENTS IN ALASKA 

on brief prospecting activity at Kukak Bay for copper and 

gold, and prospecting occurred sporadically after 1920 

particularly in the area immediately south of Kulik Lake and 

along Shelikof Strait (see claims summary in Cobb, 1980). 

But owing to the remoteness, lack of producible surface 

mineralization, and withdrawal from mineral entry, the 

Katmai region missed intensive exploratory activity that 

was typical of mining districts elsewhere in Alaska. 

The earliest systematic field studies in the region were 

carried out by industry while exploring for hydrocarbons. 

The publicly available data through 1975 were compiled by 

Magoon and others (1976) as a map, which includes that 

part of the study area north of Cape Chiniak and east of 

Kulik Lake (fig. 2). The first geologic map of the Mount 

Katmai quadrangle (Keller and Reiser, 1959) was based on 

mapping carried out from five fieldcamps occupied over the 

course of one summer, supplemented by air-photo interpretation. Use of helicopters in our study provided vastly better 

access, especially to the more remote parts of the study 

area. 

Numerous studies were carried out in the Valley of Ten 

Thousand Smokes after 1960, focusing on the volcanic 

deposits and history of the 1912 Novarupta eruption. These 

studies continue today (see Eichelberger and others, 1991); 

most have dealt with volcanic processes, although Hildreth 

(1983) mapped the boundary of the 1912 ash-flow deposit. 

The Katmai region is part of the Peninsular terrane of 

Jones and Silberling (1979), which is adjacent to the 

Chugach terrane on the southeast. Wilson and others (1985) 

proposed renaming the Peninsular terrane the Alaska Peninsula terrane and subdividing it into the Chignik and 

Iliamna subterranes. 

PRESENT STUDY 

Fieldwork was carried out during the summers of 1983 

through 1987. Due to the undeveloped nature and remoteness of the study area, self-supporting fieldcamps were 

needed throughout the period of fieldwork. The research 

vessel Don J. Miller served as both helicopter platform and 

living quarters on the Pacific coast (parts of two seasons). 

Fieldcamps were established at Becharof Lake (two seasons), Naknek Lake (one season), and Battle Lake (two 

seasons). Commercial facilities in King Salmon were also 

used briefly. 

MAP I-2032: QUATERNARY GEOLOGIC MAP OF THE 

MOUNT KATMAI QUADRANGLE AND ADJACENT PARTS OF 

THE NAKNEK AND AFOGNAK QUADRANGLES, ALASKA 

Quaternary deposits are those less than 1.65 million 

years old; that is, 1. 65 Ma. Quaternary deposits in the 

Katmai study area are mainly either glacial deposits, or 

volcanic rocks and deposits of the active Aleutian volcanic 

arc. Although the entire Katmai area was glaciated several 

times, thick glacial deposits occur only west of the Aleutian 

Range in the Bristol Bay lowlands. The mountain lakes 

Naknek, Brooks, Grosvenor, Kulik, and Nanwhyenuk are 

dammed by moraines left at their west ends after the last 

major glaciation. The lake basins were ice free by at least 

10,300 yr ago. The glaciers that scoured these basins 

originated in the adjacent Aleutian Range to the east. 

Prominent moraines between the west end of Becharof Lake 

and Bristol Bay were formed by glaciers that had moved 

south in Shelikof Strait and poured northwest through a low 

in the Aleutian Range. 

Volcanic deposits of the Aleutian volcanic arc are 

found chiefly at or near the Aleutian Range crest, which in 

part consists of active stratovolcanoes. Rhyolitic or dacitic 

ash-flow tuffs occur at the south margin of the Katmai study 

area, in the Valley of Ten Thousand Smokes, and at 

Kaguyak Crater. Airfall deposits of the 1912 eruption are 

more than a meter thick in the area from the head of the 

Valley of Ten Thousand Smokes east to Shelikof Strait 

(Judy Fierstein, USGS, written commun., 1991). Several 

warm springs near the crest of the Aleutian Range are 

additional evidence of continuing volcanic activity. 

MAP I-2204: GEOLOGIC MAP OF THE MOUNT KATMAI 

QUADRANGLE AND ADJACENT PARTS OF THE NAKNEK 

AND AFOGNAK QUADRANGLES, ALASKA 

The Katmai study area is a continental margin that has 

been the site of several cycles of subduction-generated 

volcanism and associated intrusive activity. The oldest 

rocks in the study area of certain age are submarine basalt 

flows and diabase sills of the Cottonwood Bay Greenstone, 

now metamorphosed to greenschist facies. In the Katmai 

region, this unit occurs near the south margin of the study 

area as remnants of older rocks (roof pendants) that were 

intruded during Jurassic time (205-138 Ma). The basalt 

flows crop out near interbedded marine limestone and basalt 

flows; the limestone and flows are assigned to the Late 

Triassic (210-205 Ma) Kamishak Formation that overlies 

the Cottonwood Bay Greenstone in the Iliamna quadrangle 

north of the Katmai area (Detterman and Reed, 1980). 

Some metamorphic rocks of Paleozoic(?) (570-240 

Ma) or early Mesozoic (240-190 Ma) age are assigned to 

the Kakhonak Complex and may be older than the Cottonwood Bay Greenstone. The metamorphic rocks crop out in 

a northeast-southwest trending belt as roof pendants within 

Jurassic intrusive rocks. These rocks were probably metamorphosed by heat from the intrusions. Nonmetamorphosed 

parent rocks of the Kakhonak Complex in the Katmai area 

as well as in the Iliamna quadrangle include exposed, 

pre-Middle Jurassic rocks. However, quartzite and 

potassium-feldspar-bearing gneiss exposed on an island in 
GEOLOGIC INVESTIGATIONS IN THE KA TMAI REGION 7 

Naknek Lake have no obvious compositional equivalents 

among exposed nonmetamorphosed rocks, and their parent 

rocks may be otherwise unknown Paleozoic(?) rocks. The 

gneiss may have recrystallized under conditions of regional 

metamorphism prior to intrusion of the batholith. 

The Late Triassic(?) and Early Jurassic Talkeetna 

Formation- volcanic rocks and interbedded marine sedimentary rocks-represents a volcanic arc (Reed and 

Lanphere, 1973) that crops out as far as 500 km to the north 

in the Talkeetna Mountains (Martin, 1926). The volcanic 

rocks are erupted equivalents of magmas that cooled underground to form the Alaska-Aleutian Ranges batholith. The 

intrusive rocks in the Katmai region are chiefly tonalite and 

granodiorite but include quartz diorite and granite. 

Potassium-argon (K-Ar) ages of 11 samples range from 

about 173 Ma to about 153 Ma (Reed and Lanphere, 1972; 

Shew and Lanphere, 1992); that is, from late Early to Late 

Jurassic time. Unlike areas to the north, no intrusive rocks 

of Cretaceous age (138-65 Ma) have yet been found in the 

Katmai region. One reason that some of the batholithic 

rocks have younger ages than the volcanic rocks is that 

K-Ar geochronology measures the time of cooling rather 

than intrusion, and subsurface intrusions cool more slowly 

than volcanic rocks erupted at the ground surface. 

Two important results of the Katmai study are more 

detailed age determinations of the batholithic rocks and a 

better understanding of the distribution of prebatholith wall 

rocks. 

The Naknek Formation, the most extensive rock unit 

of the Alaska Peninsula, was formed in Late Jurassic time 

(160-135 Ma). Subdivision of this widespread rock unit 

into five members (Detterman and others, in press) has been 

another important contribution of the Katmai study. The 

sequence of members indicates inundation of a continental 

margin by seas, ending with rapid uplift of the source area 

in the Alaska-Aleutian Range batholith to the northwest. 

The lowermost member is conglomerate and fluvial (river) 

sandstone; next is mixed marine and nonmarine sandstone 

and marine siltstone. The three youngest members are all 

marine rocks. The uppermost member occurs almost exclusively in the Katmai study area and consists of marine 

sandstone and conglomerate. 

Cretaceous rocks in the Katmai region are, from oldest 

to youngest, the Staniukovich, Herendeen, Pedmar, and 

Kaguyak Formations. All are marine rocks, the Kaguyak 

Formation having structures indicative of deposition in a 

deep marine basin by submarine landslides (Keller and 

Reiser, 1959; Detterman and Miller, 1985). Some of these 

rocks in the northeast part of the study area were well 

known beforehand, but their distribution in the central and 

southern part of the study area was poorly known. In 

particular, the Pedmar Formation is one of only two local 

occurrences of rocks of Albian age (125-115 Ma) on the 

Alaska Peninsula (Detterman and others, in press); during 

the course of this study a third occurrence was discovered, 

and the unit was formally defined. 

Thick sequences of marine and continental rocks of 

Tertiary age (65-1.65 Ma) occur on the southern Alaska 

Peninsula (Detterman and others, in press) and in the 

subsurface of the Cook Inlet region (Calderwood and 

Fackler, 1972). Tertiary strata are thin, however, in the 

Katmai area where they are preserved mainly along Shelikof Strait. The lower Tertiary Copper Lake Formation 

occurs near Cape Douglas, and the upper Oligocene to 

lowermost Miocene (30-20 Ma) Hemlock Conglomerate is 

exposed near Cape Nukshak. The Copper Lake Formation 

consists of well-indurated conglomerate, fluvial sandstone, 

and siltstone. The younger Hemlock Conglomerate comprises poorly indurated conglomerate, fluvial sandstone 

including volcanic tuff beds, shale, and coal. Tertiary 

sedimentary rocks occur locally west of the Aleutian Range 

crest in the Katmai region; their localized development 

suggests deposition in small isolated basins. 

Early to middle Tertiary lava flows, domes, and dikes 

crop out in the Bristol Bay lowlands in the western part of 

the Katmai area. The flows are mainly andesitic in composition, whereas crosscutting dikes and plugs are basaltic. 

These western volcanic rocks are little altered, which may 

reflect a shallow level of erosion and (or) absence of major 

centers of hydrothermal or magmatic activity. Five K-Ar 

ages of the western lava flows range from about 44 to 34 

Ma, and a single dike is about 25 Ma (Shew and Lanphere, 

1992). 

Tertiary plutons northwest of the Bruin Bay fault, in 

the Alaska-Aleutian Ranges batholith, are chiefly granodiorite and quartz monzodiorite. K-Ar ages of nine samples 

range from about 38 to 26 Ma (Reed and Lanphere, 1972; 

Shew and Lanphere, 1992). Contact metamorphic effects 

(silicification and gossan development) are locally prominent where Tertiary plutons have intruded Mesozoic sedimentary rocks east of the Bruin Bay fault. 

Sills, dikes, and plutons of tonalite or quartz diorite 

occur northwest of the Aleutian Range crest in the central 

part of the study area. These shallow intrusives are associated with gossans developed both in the intrusives and in 

their sedimentary wall rocks. Due to common alteration of 

the intrusive rocks, no radiometric ages are available. The 

rocks intrude sedimentary units as young as Cretaceous. 

Late Tertiary lava flows, dikes, sills, and small plutons 

east of the Aleutian Range crest are a part of the Aleutian 

volcanic arc that was active during Miocene and Pliocene 

(24-1.65 Ma) time. Extrusive rocks are chiefly andesitic 

and dacitic lava flows that overlie and locally deform the 

sedimentary rocks of the Hemlock Conglomerate. Both 

sedimentary and volcanic rocks have been intruded by small 

plugs and plutons associated with extensive hydrothermal 

alteration, which is manifested primarily as gossans. Two 

lava flows of the eastern volcanic group are about 14 Ma, 
8 MINERAL RESOURCE ASSESSMENTS IN ALASKA 

and several samples of the intrusive rocks range from about 

10 to 2.5 Ma (Shew and Lanphere, 1992). 

Another important result of the Katmai AMRAP study 

has been more detailed definition of the distribution, nature, 

and age of these Tertiary intrusive and volcanic rocks. 

The major structural feature of the study area is the 

Bruin Bay fault, a high-angle reverse fault that extends from 

400 km to the north in Cook Inlet (Detterman and others, 

1976) to Becharof Lake at the south margin of the Katmai 

study area. Movement is clearly up on the west side of the 

fault in the Katmai study area. In the Iliamna quadrangle, as 

much as 3 km of vertical offset (stratigraphic throw) can be 

demonstrated, and there is evidence for as much as 65 km 

of right-lateral offset (Detterman and Reed, 1980; Detterman and Hartsock, 1966). Uplift began in Late Jurassic 

time, leading to deposition of the Naknek Formation to the 

southeast of the fault (Egbert and Magoon, 1981). The last 

movement occurred no later than middle Tertiary time, 

based on the ages of two plutons intruded along the fault 

near Kulik Lake. 

Two main periods of folding have occurred in the 

Katmai region. Northwest of the Bruin Bay fault, rocks 

older than the Late Triassic(?) and Early Jurassic Talkeetna 

Formation are clearly folded, probably due to intrusion of 

adjacent plutons in Early to Middle Jurassic time. The 

Talkeetna Formation is tilted but is not folded. Southeast of 

the Bruin Bay fault, rocks as young as the Miocene volcanic 

rocks are regionally folded. In both areas fold axes trend 

generally northeast-southwest, parallel to the structural 

grain of the Alaska Peninsula elsewhere (Burk, 1965). 

Southeast of the Bruin Bay fault, sedimentary and volcanic 

rocks are commonly fractured or have minor faults, quartz 

veins, or dikes of average northwesterly trend. 

OPEN-FILE REPORT 86-586: ANALYTICAL RESULTS AND 

SAMPLE LOCALITY MAP OF STREAM-SEDIMENT AND 

HEAVY-MINERAL-CONCENTRATE SAMPLES FROM THE 

MOUNT KA TMAI QUADRANGLE, AND PORTIONS OF THE 

NAKNEK, AFOGNAK, AND ILIAMNA QUADRANGLES, 

ALASKA 

Stream sediments are, ideally, an average sample of 

the bedrock underlying an entire drainage basin and can 

provide a rapid, cost-effective method for systematically 

sampling a large area. In glaciated regions, however, the 

results must be interpreted with caution because of the 

potential for contamination by glacial deposits. During this 

study, a sample of stream sediments was collected at nearly 

all junctions of two streams that had no more junctions 

upstream (about one sample every 5-10 km2

). 

Results of analyses by semiquantitative emission spectrograph for 31 elements potentially indicative of mineralization are presented in this report for the bulk streamsediment samples and for high-density concentrates. A map 

showing localities of 1 ,243 sampling sites is presented as 

well. The following elements are included: copper, silver, 

molybdenum, lead, zinc, boron, gold, nickel, cobalt, 

arsenic, antimony, and tungsten. 

OPEN-FILE REPORT 87-615: MINERALOGY AND 

SAMPLE-LOCALITY MAP OF THE NONMAGNETIC 

HEAVY -MINERAL-CONCENTRATE SAMPLES FROM THE 

MOUNT KATMAI QUADRANGLE AND PORTIONS OF THE 

NAKNEK, AFOGNAK, AND ILIAMNA QUADRANGLES, 

ALASKA 

Identifications of ore-forming minerals in the streamsediment samples are tabulated. Samples are high-density, 

low-magnetic concentrates from bulk stream-sediment samples. Identifications are by visual examination aided by 

X-ray diffraction. 

OPEN-FILE REPORT 88-422: ANALYTICAL DATA AND 

SAMPLE LOCALITY MAP FOR AQUA-REGIA LEACHATES OF 

STREAM SEDIMENTS ANALYZED BY ICP FROM THE 

MOUNT KATMAI QUADRANGLE, AND PORTIONS OF THE 

NAKNEK, AFOGNAK, AND ILIAMNA QUADRANGLES, 

ALASKA 

Analytical results for 34 elements in aqua-regia leaches 

of the stream-sediment samples are presented. Leaching 

preferentially oxidizes sulfide minerals and minerals formed 

during rock alteration, as well as others, so the leaches 

ideally concentrate elements that reflect mineralization and 

alteration. Analytical results include copper, silver, lead, 

molybdenum, zinc, boron, gold, nickel, cobalt, arsenic, 

tin, antimony, tungsten, chromium, bismuth, cadmium, 

barium, and manganese. 

OPEN-FILE REPORT 89-570: SAMPLE LOCALITY MAPS, 

ANALYTICAL DATA, AND STATISTICAL SUMMARY OF 

ANALYSES OF ROCK SAMPLES FROM THE MOUNT KATMAI 

QUADRANGLE AND ADJACENT PORTIONS OF THE NAKNEK 

AND AFOGNAK QUADRANGLES, ALASKA 

Results are presented on 1 ,205 bedrock samples analyzed by semiquantitative emission spectrograph for 31 

elements potentially indicative of mineralization. Results 

are also included for analyses of selected samples by 

methods more sensitive for elements of particular interest 

such as gold and mercury. Results are grouped according to 

geologic unit and are statistically analyzed to determine the 

concentration of each element that is considered unusually 

high (anomalous) for each rock type in the study area. A 

map showing the localities of sample sites is included. Of 

the ore-related elements, anomalous concentrations were 

noted in copper, molybdenum, lead, and zinc, less commonly in silver, and uncommonly in gold. The geologic 

setting of each of the 197 anomalous samples is discussed in 

Bulletin 2020. 
GEOLOGIC INVESTIGATIONS IN THE KA TMAI REGION 9 

MF-2021-A: GEOCHEMICAL MAP SHOWING THE 

DISTRIBUTION OF SELECTED ELEMENTS DETERMINED IN 

STREAM SEDIMENTS FROM THE MOUNT KATMAI AND 

PORTIONS OF THE AFOGNAK AND NAKNEK 

QUADRANGLES, ALASKA 

Maps MF-2021-A through 2021-D show the spatial 

distribution of anomalies identified by the different analytical techniques reported in Open-File Reports 86-586, 

87-615, and 88-422 for the set of stream-sediment samples. The analytical results of all techniques are interpreted 

together in Bulletin 2020. 

Results are statistically analyzed to determine the 

concentration of each element that is unusually high (anomalous) in stream sediments according to the dominant type 

of bedrock that underlies the drainage basin of the sample. 

Spatial clustering of samples having anomalous concentrations and the occurrence of multiple elements in anomalous 

concentrations in those samples indicate likely sulfide (iron, 

copper, lead, zinc, or arsenic) and (or) precious-metal 

(gold, silver) mineralization in tracts near Cape Douglas 

and Kulik Lake and in the central part of the study area 

(fig. 2). 

MF-2021-B: GEOCHEMICAL MAPS SHOWING THE 

DISTRIBUTION OF SELECTED LEACHABLE METALS 

DETERMINED BY ICP IN STREAM SEDIMENTS FROM THE 

MOUNT KATMAI AND PORTIONS OF THE AFOGNAK AND 

NAKNEK QUADRANGLES, ALASKA 

Results confirm most of the three tracts outlined in 

MF-2021-A. A fourth tract defined exclusively by leachates is the area underlain by Tertiary volcanic rocks north 

of Naknek Lake. Such an alteration signature may reflect 

widespread, low-grade cooling alteration of the lava flows; 

it may also reflect older deposits of glacial till, or buried 

altered rocks. 

MF-2021-C: GEOCHEMICAL MAP SHOWING THE 

DISTRIBUTION OF SELECTED ELEMENTS DETERMINED IN 

NONMAGNETIC HEAVY -MINERAL CONCENTRATES FROM 

THE MOUNT KATMAI AND PORTIONS OF THE AFOGNAK 

AND NAKNEK QUADRANGLES, ALASKA 

The high-density concentrates should contain most 

ore-forming minerals. Samples anomalous in copper, lead, 

gold, or silver occur near Cape Douglas; anomalous concentrations of copper, lead, zinc, molybdenum, and boron 

occur from Kukak Bay southwest to Katmai Bay, near 

Kejulik Pass at the south margin of the study area, and in 

the central part of the study area. Anomalous concentrations 

of copper, molybdenum, lead, and zinc occur immediately 

south of Kulik Lake. A few samples having anomalous 

concentrations of gold, molybdenum, and silver occur in 

the northwest part of the map area, in the tract underlain by 

Tertiary volcanic rocks. 

MF-2021-D: MINERALOGIC MAP SHOWING THE 

DISTRIBUTION OF SELECTED MINERALS IDENTIFIED IN 

NONMAGNETIC HEAVY-MINERAL CONCENTRATES FROM 

THE MOUNT KATMAI AND PORTIONS OF THE AFOGNAK 

AND NAKNEK QUADRANGLES, ALASKA 

Pyrite-, copper-, lead-, and zinc-sulfide minerals, and 

uncommon gold occur in samples from southwest of Cape 

Douglas. A few samples from a tract underlain by altered 

volcanic rocks at the south margin of the study area have 

copper- and zinc-sulfide minerals. A few samples from the 

center of the study area and from a tract south of Kulik Lake 

have copper-, lead-, or zinc-sulfide minerals and a tungsten 

mineral. The tract north of Naknek Lake, underlain by 

Tertiary volcanic rocks, yielded a few samples having 

tungsten, tin, or zinc minerals. 

BULLETIN 2020: INTERPRETATION OF EXPLORATION 

GEOCHEMICAL DATA FROM THE MOUNT KATMAI 

QUADRANGLE AND ADJOINING PARTS OF THE AFOGNAK 

AND NAKNEK QUADRANGLES, ALASKA 

Interpretation of analytical results for the bedrock and 

stream-sediment samples is aided by comparison with 

results from mineralized tracts in adjacent areas. In the 

Chignik-Sutwik Island quadrangles south of the Katmai 

area, porphyry mineralization occurs near Tertiary or Quaternary intrusions in marine and nonmarine sedimentary 

rocks (Wilson and Cox, 1983). The metals of interest in a 

porphyry mineral deposit are chiefly copper and molybdenum but may include gold, silver, or zinc. The ore minerals 

occur in thin veins at the margins of plutons or in adjacent 

wall rocks. Areas of possible porphyry mineralization occur 

in the Ugashik and Karluk quadrangles as well, immediately south of the Katmai area (Church and others, 1989b). 

In these areas, stream sediments have anomalous concentrations of copper, molybdenum, and one or more of lead, 

zinc, arsenic, silver, and gold; rock samples have anomalous concentrations of these elements and tin or tungsten. 

Precious-metal veins occur at the Apollo mine on Unga 

Island 470 km southwest of Katmai. The Apollo produced 

$3 million worth of gold and silver between 1893 and 1908. 

The occurrence is as near-vertical quartz veins in Tertiary 

lava flows and domes (Wilson and others, 1988). The 

Apollo and other prospects on Unga Island are sited on 

faults that have localized quartz veins, silicification, and 

alteration (White and Queen, 1989). Stream sediments in 

the area of the Apollo mine have anomalous concentrations 

of silver, copper, lead, molybdenum, and zinc; bedrock 

samples have anomalous concentrations of these elements 

as well as gold (J. Frisken, written commun., 1988). 

Numerous prospects and mineral claims for gold, 

silver, copper, and iron have been filed in the Iliamna 

quadrangle north of the Katmai region. These occurrences 

are either replacement deposits (skarns) formed in limestone 
10 MINERAL RESOURCE ASSESSMENTS IN ALASKA 

or volcanic rocks of the Talkeetna Formation at the contact 

with intrusive rocks or are magnetite in gabbro of the 

Jurassic batholith (Detterman and Reed, 1980). Gabbro and 

limestone are uncommon in the Katmai study area, and 

there are few appropriate geochemical anomalies. Thus, 

there is little evidence for similar deposits in the Katmai 

region. A gold-, silver-, and copper-bearing quartz vein 

occurs 13 km north of Kulik Lake in slightly altered, 

Tertiary volcanic rocks; the vein probably formed above a 

buried pluton. 

Bedrock and stream-sediment samples from the Katmai area that have anomalous concentrations of ore-related 

elements were examined for spatial clustering. Some anomalous samples occur isolated from others and (or) have 

concentrations that only marginally meet the definition of 

anomalous. These samples probably represent weakly 

developed mineralization. Other anomalous streamsediment samples occur in tracts having few anomalous 

bedrock samples and no other geologic evidence for mineralization. These results are provisionally interpreted to be 

due to contamination of stream sediments by glacial deposits. Tracts having ( 1) clusters of both bedrock and stream 

sediment samples that are (2) anomalous in several elements, and (3) evidence for geologic processes favorable 

for mineralization, are discussed in detail. 

Anomalous concentrations in both bedrock and streamsediment samples of copper, molybdenum, lead, zinc, 

silver, arsenic, tin, and tungsten are suggestive of undiscovered porphyry copper or molybdenum deposits. Such 

anomalies occur in tracts at the center of the study area, at 

Cape Douglas in the northeast, and immediately south of 

Kulik Lake at the north margin of the study area. Less 

intensely developed patterns of anomalies occur as well at 

the south margin of the study area near Kejulik Pass and in 

the northwest. In all of these tracts there are porphyritic 

intrusive rocks or there is permissive evidence for the 

occurrence of such rocks at shallow depth. 

Anomalous concentrations of copper, molybdenum, 

lead, zinc, silver, and arsenic may indicate the presence of 

polymetallic veins. Where gold, silver, mercury, or arsenic 

occur in anomalous concentrations, potential gold-silver 

(precious metal) veins are suggested. Samples having 

anomalous concentrations of such elements occur in the 

same tracts as those outlined for porphyry deposits: in the 

center of the study area, near Kulik Lake, and at Cape 

Douglas. Another tract having a large number of samples 

anomalous in the vein suite is the area from Cape Douglas 

south to Katmai Bay. This tract is underlain by altered 

Tertiary and Quaternary volcanic rocks that have abundant 

quartz veins, fractures, and dikes and other small intrusive 

masses that may have been sources of mineralizing fluids. 

The occurrence of active fumaroles or warm springs 

near some of the Quaternary volcanoes is permissive of 

undiscovered hot-springs gold deposits. Some streamsediment samples collected in basins draining the flanks of 

active volcanoes· have anomalous concentrations of elements characteristic of hot-springs deposits (such as mercury, lead, arsenic, and silver). However, specific sites 

having well-developed geochemical anomalies were not 

identified. 

MF-2021-E: MAP AND TABLE SHOWING K-AR AGES FROM 

THE MOUNT KATMAI AND ADJACENT PARTS OF THE 

NAKNEK AND AFOGNAK QUADRANGLES, ALASKA 

Analytical data are presented for 46 new potassiumargon ages determined on samples of intrusive and volcanic 

rocks collected during the course of this study. Data are 

included for 18 additional ages that were previously determined but some not previously published. Sample localities 

are plotted on a base geologic map. The ages define two 

main clusters: an early to middle Jurassic intrusive event 

(the Alaska-Aleutian Ranges batholith) and a middle Tertiary to Quaternary, intrusive and volcanic event that includes 

the modem Aleutian volcanic arc. The new sample ages 

have important implications for the mineral-resource assessment: for example, mineralization in areas underlain by 

batholithic rocks is preferentially concentrated near plutons 

of Tertiary age. 

MF-2021-F: MINERAL AND ENERGY RESOURCE 

ASSESSMENT MAPS OF THE MOUNT KATMAI, NAKNEK, 

AND WESTERN AFOGNAK QUADRANGLES, ALASKA 

These maps summarize the evidence and interpretations in the other publications, and outline tracts having 

evidence permissive or suggestive of undiscovered mineral 

deposits. A major contribution of the Katmai study is the 

first systematic resource assessment of the region. 

In the north-central part of the study area, near Kulik 

Lake, evidence is favorable for the occurrence of an 

undiscovered porphyry-copper deposit and (or) for polymetallic vein deposits. There is also potential for placer gold 

deposits in this tract. Bedrock in this tract includes Tertiary 

plutons that have intruded Jurassic plutons and their older 

wall rocks, similar to the types of bedrock that occur around 

claims and mineral occurrences in the Iliamna quadrangle. 

Specific evidence for mineralization includes quartz veins, 

disseminated pyrite, rock alteration, and anomalous concentrations of metals including copper, gold, and silver in 

both rock samples and stream sediments. Some claims and 

prospect pits occur in the area. 

No direct evidence for replacement (skarn) deposits at 

the margins of Jurassic or Tertiary plutons was found in the 

Katmai region during the course of this study. 

There is potential for a porphyry copper (molybdenum) 

deposit and (or) for polymetallic vein deposits in the central 

part of the study area. The geologic setting is Tertiary 

plutons that have intruded fractured and locally altered, 
REFERENCES CITED 11 

Mesozoic sedimentary rocks. Anomalous quantities of copper, lead, zinc, silver, and gold occur in both bedrock and 

stream-sediment samples. Alteration and quartz veins are 

present in the plutonic rocks. A similar geochemical signature occurs in a tract of altered volcanic rocks near Kejulik 

Pass, at the south margin of the study area. There are, 

however, no exposed intrusive rocks at Kejulik Pass except 

for small sills and dikes, and the geochemical signature is 

less intensely developed than in the central tract. 

The entire Aleutian Range, from Cape Douglas south 

to Katmai Bay, is judged to have potential for undiscovered 

deposits of porphyry copper, hot-springs gold, and (or) 

polymetallic veins. The underlying bedrock is late Tertiary 

and Quaternary volcanic rocks and small intrusive masses, 

and older Mesozoic and Tertiary sedimentary wall rocks. 

All rock types are altered or fractured, providing pathways 

for mineralizing fluids, and have quartz veins that are 

parallel to the prevalent northwest-trending fractures. Some 

geochemical anomalies are associated with areas of particularly intense alteration and veining. Anomalous concentrations of zinc, silver, copper, molybdenum, and gold are 

identified in both stream-sediment and bedrock samples. 

The number and size of undiscovered mineral deposits 

that may occur in the Katmai region are unknown. No 

producing porphyry deposits occur in similar rocks elsewhere on the Alaska Peninsula, thus it is unlikely that many 

such undiscovered deposits would occur in the study area. 

On the other hand, vein deposits may extend for only tens 

to hundreds of meters along a narrow zone, so there could 

be numerous undiscovered vein deposits within the study 

area. 

The only known mineral production from the study 

area has been from a gold-placer claim on the American 

River south of Nanwhyenuk Lake. A few tidewater claims 

for pumice (lightweight aggregate) are still valid on the 

Shelikof Strait; there has been no known production from 

these claims. Sand and gravel for construction are abundant 

in the inhabited western portion of the study area. The few 

known warm springs are too low in temperature for direct 

uses. Hydrocarbon potential within the study area is low, 

due to unfavorable rock characteristics and geologic history. Minor coal seams in Tertiary rocks along Shelikof 

Strait could constitute a small, locally marketable resource 

under favorable conditions of economics and land classification. 

MF-2021-G: MACROFOSSIL LOCALITY MAP, CHECKLISTS, 

AND PRE-QUATERNARY STRATIGRAPIDC SECTIONS OF 

THE MOUNT KATMAI QUADRANGLE AND ADJACENT 

PARTS OF THE NAKNEK AND AFOGNAK QUADRANGLES, 

ALASKA 

A total of 338 collections of macrofossils were made 

during the course of the study, many from measured 

stratigraphic sections. The report presents fossil identities, 

localities, ages, and measured sections. The combination of 

fossil and stratigraphic data is useful not only for determining the exact ages of the rocks but for describing precisely 

the sequence of environmental changes during deposition of 

the rock layers. 

Most collections are from the Naknek Formation, the 

main rock unit of the Alaska Peninsula. Marine deposits of 

the upper part of the Naknek Formation are richly fossiliferous, the clamlike genus Buchia predominating. Different 

species of Buchia indicate different marine environments. 

Ammonites-marine invertebrates related to modem 

squids-and the clam Inoceramus are important fossils in 

the Cretaceous rocks of the area. Ages of nonmarine 

Tertiary rocks are determined from plant fossils. 

REFERENCES CITED 

Andreasen, G.E., Dempsey, W.J., Vargo, J.L., and others, 1963, 

Aeromagnetic map of part of the Naknek quadrangle, Alaska: 

U.S. Geological Survey Geophysical Investigations Map 

GP-353, scale 1:125,000. 

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

the Alaska Peninsula: U.S. Geological Survey Bulletin 467, 

137 p. 

Bailey, E.A., Sutley, S.J., Arbogast, B.F., Willson, W.R., and 

Church, S.E., 1986, Analytical results and sample locality 

map of stream-sediment and heavy-mineral-concentrate samples from the Mount Katmai quadrangle, and portions of the 

Naknek, Afognak, and Iliamna quadrangles, Alaska: U.S. 

Geological Survey Open-File Report 86-586, scale 

1:250,000, 126 p. 

Bates, R.L., and Jackson, J.A., 1980, Glossary of geology: Falls 

Church, Va., American Geological Institute, 751 p. 

Bennett, G.J., and Church, S.E., 1987, Mineralogy and samplelocality map of the nonmagnetic heavy-mineral-concentrate 

samples from the Mount Katmai quadrangle and portions of 

the Naknek, Afognak, and Iliamna quadrangles, Alaska: 

U.S. Geological Survey Open-File Report 87-615, scale 

1:250,000, 39 p. 

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

and continental margin: Geological Society of America Memoir 99, 250 p. 

Calderwood, K.W., and Fackler, W.C., 1972, Proposed stratigraphic nomenclature for the Kenai Group, Cook Inlet basin, 

Alaska: American Association of Petroleum Geologists Bulletin, v. 56, p. 739-754. 

Church, S.E., and Arbogast, B.F., 1989, Geochemical map 

showing the distribution of selected elements determined in 

nonmagnetic heavy-mineral concentrates from the Mount 

Katmai and portions of the Afognak and Naknek quadrangles, Alaska: U.S. Geological Survey Miscellaneous Field 

Studies Map MF-2021-C, scale 1:250,000. 

Church, S.E., Bailey, E.A., and Riehle, J.R., 1989a, Geochemical map showing the distribution of selected elements determined in stream sediments from the Mount Katmai and 

portions of the Afognak and Naknek quadrangles, Alaska: 
12 MINERAL RESOURCE ASSESSMENTS IN ALASKA 

U.S. Geological Survey Miscellaneous Field Studies Map 

MF-2021-A, scale 1:250,000. 

Church, S.E., and Bennett, G.J., 1989, Mineralogic map showing 

the distribution of selected minerals identified in nonmagnetic 

heavy-mineral concentrates from the Mount Katmai and 

portions of the Afognak and Naknek quadrangles, Alaska: 

U.S. Geological Survey Miscellaneous Field Studies Map 

MF-2021-D, scale 1:250,000. 

Church, S.E., Frisken, J.G., and Wilson, F.H., 1989b, Interpretation of exploration geochemical data from the Ugashik, 

Bristol Bay, and western Karluk quadrangles, Alaska: U.S. 

Geological Survey Bulletin 1858, 45 p. 

Church, S.E., and Motooka, J.M., 1989, Geochemical maps 

showing the distribution of selected leachable metals determined by ICP in stream sediments from the Mount Katmai 

and portion of the Afognak and Naknek quadrangles, Alaska: 

U.S. Geological Survey Miscellaneous Field Studies Map 

MF-2021-B, scale 1:250,000. 

Church, S.E., Riehle, J.R., and Goldfarb, R.J., in press, Interpretation of exploration geochemical data from the Mount 

Katmai quadrangle and parts of the Mognak and Naknek 

quadrangles, Alaska: U.S. Geological Survey Bulletin 2020. 

Church, S.E., Riehle, J.R., Magoon, L.B., and Campbell, D.L., 

1992, Mineral and energy resource assessment maps of the 

Mount Katmai, Naknek, and western Afognak quadrangles, 

Alaska; U.S. Geological Survey Miscellaneous Field Studies 

Map MF-2021-F, scale 1:250,000 

Cobb, E. H., 1980, Summaries of data on and lists of references to 

metallic and selected nonmetallic mineral deposits in fifteen 

quadrangles in southwestern and west-central Alaska: U.S. 

Geological Survey Open-File Report 80-909, 103 p. 

Cox, D.P., Barton, P.B., and Singer, D.A., 1986, Mineral 

deposit models, in Cox, D.P., and Singer, D.A., eds., 

Mineral deposit models: U.S. Geological Survey Bulletin 

1693, p. 1-10. 

Detterman, R.L., and Hartsock, J.K., 1966, Geology of the 

Iniskin-Tuxedni region, Alaska: U.S. Geological Survey 

Professional Paper 512, 78 p. 

Detterman, R.L., Hudson, Travis, Plafker, George, Tysdal, R.G., 

and Hoare, J.M., 1976, Reconnaissance geologic map along 

the Bruin Bay and Lake Clark faults in the Kenai and Tyonek 

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

Report 76-477, scale 1:250,000. 

Detterman, R.L., and Miller, J.W., 1985, Kaguyak FormationAn Upper Cretaceous flysch deposit, in Bartsch-Winkler, 

Susan, and Reed, K.M., eds., The United States Geological 

Survey in Alaska-Accomplishments during 1983: U.S. 

Geological Survey Circular 945, p. 49-51. 

Detterman, R.L., Miller, J.W., Case, J.E., Wilson, F.H., and 

Yount, M.E., in press, Stratigraphic framework of the Alaska 

Peninsula: U.S. Geological Survey Bulletin 1969-A. 

Detterman, R.L., and Reed, B.L., 1980, Stratigraphy, structure, 

and economic geology of the Iliamna quadrangle, Alaska: 

U.S. Geological Survey Bulletin 1368-B, 86 p. 

Egbert, R.M., and Magoon, L.B., 1981, Petrography, provenance, and tectonic significance of Middle and Upper Jurassic sandstone from Tuxedni Bay, Cook Inlet, Alaska, in 

Albert, N.R.D., and Hudson, Travis, eds., The United States 

Geological Survey in Alaska-Accomplishments during 

1979: U.S. Geological Survey Circular 823-B, p. 86-88. 

Ehrlich, Olga, Motooka, J.M., VanTrump, George, Jr., and 

Church, S.E., 1988, Analytical data and sample locality map 

for aqua-regia leachates of stream sediments analyzed by ICP 

from the Mount Katmai quadrangle, and portions of the 

Naknek, Afognak, and Iliamna quadrangles, Alaska: U.S. 

Geological Survey Open-File Report 88-422, scale 

1:250,000, 72 p. 

Eichelberger, J.C., Hildreth, Wes, and Papike, J.J., 1991, The 

Katmai Scientific Drilling Project, surface phase: Investigation of an exceptional igneous system: Geophysical Research 

Letters, v. 18, p. 1513-1517. 

Griggs, R.F., 1922, The Valley of Ten Thousand Smokes: 

Washington, D.C., The National Geographic Society, 341 p. 

Grybeck, Donald, and Berg, H.C., 1982, The Alaska mineral 

resource assessment program: U.S. Geological Survey OpenFile Report 82-441, 61 p. 

Harris, D.P., 1984, Mineral resources appraisal-Mineral endowment, resources, and potential supply: Concepts, methods, 

and cases: Oxford, Clarendon Press, 445 p. 

Hildreth, Wes, 1983, The compositionally zoned eruption of 1912 

in the Valley of Ten Thousand Smokes, Katmai National 

Park, Alaska: Journal of Volcanology and Geothermal 

Research, v. 18, p. 1-56. 

Jones, D.L., and Silberling, N.J., 1979, Mesozoic stratigraphy-The key to tectonic analysis of southern and central 

Alaska: U.S. Geological Survey Open-File Report 79-1200, 

37 p. 

Keller, A.S., and Reiser, H.N., 1959, Geology of the Mount 

Katmai area, Alaska: U.S. Geological Survey Bulletin 

1058-G, scale 1:250,000, p. 261-298. 

MacKevett, E.M., Jr., Singer, D.A., and Holloway, C.D., 1978, 

Maps and tables describing metalliferous mineral resource 

potential of southern Alaska: U.S. Geological Survey OpenFile Report 78-1-E, scale 1:1,000,000. 

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. 

Martin, G.C., 1920, The Alaska mining industry in 1918: U.S. 

Geological Survey Bulletin 712, p. 11-52. 

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

Miller, J.W., Detterman, R.L., and Elder, W.P., in press, 

Macrofossil locality map, checklists, and pre-Quaternary 

stratigraphic sections of the Mount Katmai quadrangle and 

adjacent parts of the Naknek and Afognak quadrangles, 

Alaska: U.S. Geological Survey Miscellaneous Field Studies 

Map MF-2021-G, scale 1:250,000. 

Reed, B.L., and Lanphere, M.A., 1972, Generalized geologic 

map of the Alaska-Aleutian Range batholith showing 

potassium-argon ages of the plutonic rocks: U.S. Geological 

Survey Miscellaneous Field Studies Map MF-372, scale 

1:1,000,000. 

---1973, Alaska-Aleutian Range batholith: Geochronology, 

chemistry, and relation to circum-Pacific plutonism: Geological Society of America Bulletin, v. 84, p. 2583-2610. 

Riehle, J.R., Bailey, E.A., Church, S.E., and Yount, M.E., 

1989, Sample locality maps, analytical data, and statistical 

summary of analyses of rock samples from the Mount Katmai 
REFERENCES CITED 13 

quadrangle and adjacent portions of the Naknek and Afognak 

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

Report 89-570, scale 1:250,000, 136 p. 

Riehle, J.R., and Detterman, R.L., 1993, Quaternary geologic 

map of the Mount Katmai quadrangle and adjacent parts of 

the Naknek and Afognak quadrangles, Alaska: U.S. Geological Survey Miscellaneous Investigations Series Map I-2032, 

scale 1:250,000. 

Riehle, J.R., Detterman, R.L., Yount, M.E., and Miller, J.W., 

1993, Geologic map of the Mount Katmai quadrangle and 

adjacent parts of the Naknek and Afognak quadrangles, 

Alaska: U.S. Geological Survey Miscellaneous Investigations Map Series I-2204, scale 1:250,000. 

Shew, Nora, and Lanphere, M.A., 1992, Map and table showing 

K-Ar ages from the Mount Katmai and adjacent parts of the 

Naknek and Afognak quadrangles, Alaska: U.S Geological 

Survey Miscellaneous Field Studies Map MF-2021-E, scale 

1:250,000. 

Singer, D.A., and Ovenshine, A.T., 1979, Assessing metallic 

resources in Alaska: American Scientist, v. 67, p. 582-589. 

Spurr, J.E., and Post, W.S., 1899, Report of the Kuskokwim 

expedition, in Maps and descriptions of routes of exploration 

in Alaska in 1898: Report of the Director of the U.S. 

Geological Survey, Government Printing Office, p. 28-39. 

U.S. Bureau of Mines and U.S. Geological Survey, 1980, 

Principles of a resource/reserve classification for minerals: 

U.S. Geological Survey Circular 831, 5 p. 

Wahrhaftig, Clyde, 1965, Physiographic divisions of Alaska: U.S. 

Geological Survey Professional Paper 482, 52 p. 

White, W.H., and Queen, L.D., 1989, Preliminary geologic and 

rock-chip geochemical data from drill core and trenches at the 

Shumagin gold deposit, Unga Island, Alaska: U.S. Geological Survey Open-File Report 89-361, 36 p. 

Wilson, F.H., and Cox, D.P., 1983, Geochronology, geochemistry, and tectonic environment of porphyry mineralization in 

the central Alaska Peninsula: U.S. Geological Survey OpenFile Report 83-783, 24 p. 

Wilson, F.H., Detterman, R.L., and Case, J.E., 1985, The 

Alaska Peninsula terrane: A definition: U.S. Geological 

Survey Open-File Report 85-450, 12 p. 

Wilson, F.H., White, W.H., and DuBois, G.D., 1988, Brief 

descriptions of mines, prospects, and occurrences in the Port 

Moller and Stepovak Bay quadrangles, Alaska Peninsula: 

U.S. Geological Survey Open-File Report 88-666, 128 p. 

*U.S, G.P.0.:1994-301-077:80087 

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 hydrogeology, 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 Investigations Reports are papers of an 

interpretive nature made available to the public outside the formal 

USGS publications series. Copies are reproduced on request 

unlike formal USGS publications, and they are also available for 

public inspection at depositories indicated in USGS catalogs. 

Open-Flle 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 7.5- 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 structures that are of 

economic or geologic significance. Many maps include 

correlations with the geology. 

Miscellaneous Investigations 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 7.5-minute quadrangle photogeologic maps on planimetric bases that show geology as interpreted 

from aerial photographs. 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 fields and other areas having 

petroleum potential. 

MisceUaneous Field Studies Maps are multicolor or blackand-white maps on topographic or planimetric bases for 

quadrangle or irregular areas at various scales. Pre-1971 maps 

show bedrock geology in relation to specific mining or mineraldeposit 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-and-white maps on topographic or planimetric bases 

presenting a wide range of geohydrologic data of both regular and 

irregular areas; 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, gtvmg 

comprehensive listings of U.S. Geological Survey publications are 

available under the conditions indicated below from the U.S. 

Geological Survey, Map Distribution, Box 25286, Bldg. 810, 

Federal Center, Denver, CO 80225. (See latest Price and 

Availability List.) 

''Publications of the Geological Survey, 1879-1961" may 

be purchased by mail and over the counter in paperback book form 

and as a set of microfiche. 

''Publications of the Geological Survey, 1962-1970" may 

be purchased by mail and over the counter in paperback book form 

and as a set of microfiche. 

"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 

subsequent years since the last permanent catalog may be 

purchased by mail 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 

Publications," issued annually, is available free of charge in 

paperback booklet form only. 

Selected copies of a monthly catalog ''New Publications 

of the U.S. Geological Survey" are available free of charge by 

mail or may be obtained over the counter in paperback booklet 

form only. Those wishing a free subscription to the monthly 

catalog "New Publications of the U.S. Geological Survey" should 

write to the U.S. Geological Survey, 582 National Center, Reston, 

VA 22092. 

Note.-Prices of Government publications listed in older 

catalogs, announcements, and publications may be incorrect. 

Therefore, the prices charged may differ from the prices in 

catalogs, announcements, and publications. 
~·