GEOLOGICAL SURVEY CIRCULAR 758

The Alaskan Mineral Resource 

Assessment Program:

Guide to Information Contained in the

Folio of Geologic and

Mineral Resource Maps of

the Chandalar Quadrangle, Alaska
The Alaskan Mineral Resource 

Assessment Program:

Guide to Information Contained in the

Folio of Geologic and

Mineral Resource Maps of

the Chandalar Quadrangle, Alaska

By H. N. Reiser, W. P. Brosge, J. H. DeYoung, Jr., S. P. Marsh, 

T. D. Hamilton, J. W. Cady, and N. R. D. Albert

GEOLOGICAL SURVEY CIRCULAR 758

1979
United States Department of the Interior

CECIL D. ANDRUS, Secretary

Geological Survey

H. William Menard, Director

Library of Congress Cataloging in Publication Data

Main entry under title:

The Alaskan mineral resource assessment program.

(Geological Survey circular ; 758)

Bibliography: p. 21-23.

1. Mines and mineral re sources-Alaska. 2. Mines and mineral

resources Alaska Maps. I. Reiser, H. N. II. Series:

United States. Geological Survey. Circular 758. 

QE75.C5 no. 758 [TN24.A4] 557.3'08s[553'.09798] 79-607035

Free on application to Branch of Distribution, U.S. Geological Survey, 1200 South Eads Street, Arlington, VA 22202
CONTENTS

 Page

Abstract ______________________________________________ 1

Introduction ________________________________________________ 1 

Purpose and scope _______________________________________ 1 

Geography and access ____________________________________ 1 

Mineral production and exploration _____________________________ 2 

Acknowledgments ______________________________________ 3

Geological investigations ______________________________________ 4 

Previous geological investigations _____________________________ 4 

Recent studies _________________________________________ 5

Geology of the Chandalar quadrangle ______________________________ 5 

Potassium-argon ages ____________________________________ 7

Description of component maps of the Chandalar quadrangle folio ______________ 8

Geology (map 1-375) ______________________________________ 8

Revisions of map 1-375 _________________________________ 8

Mapping _______________________________________ 8

Nomenclature ____________________________________ 8

Age assignments __________________________________ 10

Surficial geologic map (map MF-878-A) _________________________ 16

Mineral resources map (map MF-878-B) ___________________________ 18

Aeromagnetic map and interpretation (map MF-878-C, 2 sheets) ____________ 19

Geochemical maps (maps MF-878-D to I) _________________________ 19

Interpretation of Landsat imagery (map MF-878-J, 2 sheets), by Nairn R. D. Albert 20

References ____________________________________ 21

ILLUSTRATIONS

FIGURE 1. Index map of Alaska showing location of Chandalar quadrangle 3

2. Physiographic divisions of the Chandalar quadrangle ______ 4

3. Index map of the Chandalar quadrangle showing location of the Alyeska haul road and large airfields

(airplane symbols) ____________________________ _ 5

4. Metamorphic facies and K/Ar ages of rocks in the Chandalar quadrangle 6

5. Localities where the geologic map of the Chandalar quadrangle (Brosgg and Reiser, 1964) has been

revised in the compilation of the generalized geologic map for the AMRAP folio 8

6. Revisions of the northwest part of geologic map of Chandalar quadrangle (Brosgg and Reiser, 1964) 9

7. Revisions of north-central part of geologic map of Chandalar quadrangle (Brosgg and Reiser, 1964) 9

8. Revisions of northeast part of geologic map of Chandalar quadrangle (Brosg6 and Reiser, 1964) 10

9. Revision of west-central part of geologic map of Chandalar quadrangle (Brosg6 and Reiser, 1964) 10

10. Revisions of central part of geologic map of Chandalar quadrangle (Brosgl and Reiser, 1964) 11

11. Revision of southwest part of geologic map of Chandalar quadrangle (Brosg6 and Reiser, 1964) 12

12. Correlation and description of the map units shown on the generalized geologic map of the Chandalar

quadrangle _________________________________ 14

13. Generalized geologic map of northern part of Chandalar quadrangle showing the possibly unconformable

relation of the Upper Devonian Hunt Fork Shale to the older Paleozoic sedimentary rocks, to the schist, 

and to the calcareous rocks that ar3 equivalent to part of the schist 16

TABLE

Page

TABLE 1. Component maps of the Chandalar quadrangle mineral resource assessment program _____________ 2

m
The Alaskan Mineral Resource Assessment Program: Guide to

Information Contained in the Folio of Geologic and Mineral

Resource Maps of the Chandalar Quadrangle, Alaska

By H. N. Reiser, W. P. Brosge, J. H. DeYoung, Jr.,

S. P. Marsh, T. D. Hamilton, J. W. Cady, and

N. R. D. Albert

ABSTRACT

The Chandalar quadrangle in east-central Alaska was investigated 

by a multidisciplinary research group to assess the mineral resource 

potential of the quadrangle. This circular serves as a guide to and 

integrates with a folio of 10 miscellaneous field study (MF) maps and 2 

open-file (OF) reports (table 1) concerned with the geology, 

geophysics, geochemistry, Landsat imagery, and mineral resources 

of the area.

Revisions to the previously published Chandalar quadrangle 

geologic map, a new radiometric age determination, and a bibliography are also included.

INTRODUCTION

PURPOSE AND SCOPE

This circular and the related but separately available 

folio of maps and open-file reports of the Chandalar 

quadrangle, Alaska, are one of a series of similar publications resulting from the Alaskan Mineral Resource 

Assessment Program (AMRAP). Their purpose is to 

provide the basis for a sound long-range national minerals policy and also to aid in Federal, State and industry 

decisions in planning exploration and development of 

Alaskan resources.

The Chandalar quadrangle was selected for early 

study under AMRAP because of impending land selection decisions, the area's potential as the possible eastern extension of the southwestern Brooks Range copper belt (Hawley, 1976), its known gold mineralization, 

and because the area has recently been made more 

accessible by completion of the Alyeska Haul Road.

The present report integrates geologic data and 

mapping collected prior to AMRAP Quly 1975), and the

recent data acquired during the AMRAP-sponsored investigation.

GEOGRAPHY AND ACCESS

The Chandalar quadrangle is located in eastcentral Alaska between lat 67° and 68° N. and 

long 147° and 150° W. (fig. 1) and comprises approximately 14,200 km2 . The area includes five 

sections of two major physiographic provinces, the 

Arctic Mountains province, and the Northern 

Plateaus province (Wahrhaftig, 1965).

The rugged glaciated highlands of the eastern 

Brooks Range and Porcupine Plateau sections occupy the northern two-thirds of the quadrangle 

(fig. 2). The rounded uplands of the KokrineHodzana Highlands make up the southern part of 

the quadrangle except for a small area of the 

Yukon Flats section in the extreme southeast.

A prominent topographic low, the Kobuk 

Trench, which is probably a fault-controlled feature (Payne, 1955; Grantz, 1966), separates these 

northern and southern physiographic sections. 

Most of the Kobuk Trench coincides with the 

Ambler-Chandalar Ridge and Lowland physiographic section of Wahrhaftig, but he included the 

easternmost part of the trench along the main 

Chandalar valley in the Porcupine Plateau (fig. 2).

Drainage within the quadrangle is divided between two major tributaries of the Yukon River; 

the Chandalar River drains the quadrangle to the 

east and the Koyukuk River to the west. The valleys of the main drainages have been glaciated and 

have broad flat floors covered by alluvium and 

, glacial deposits.
TABLE 1. Component maps of the Cbandalar quadrangle mineral resource assessment program

Report Subject

U.S. Geol. Survey Misc. Geol. Inv. Map 1-375 (Brosge and Reiser, 1964) __________Reconnaissance geology. 

U.S. Geol. Survey Misc. Field Studies (MF) Maps:

MF-878- A (Hamilton, 1978) _________________________Surficial geology.

B (DeYoung, 1978) _________________________Mineral resources.

C (Cady, 1978) ____________________________Aeromagnetic contours and

interpretation.

D (Marsh and others, 1978) ____________________Geochemical distribution and

abundance of copper, 

molybdenum, and lead.

E (Marsh and others, 1978) ____________________Geochemical distribution and

abundance of zinc.

F (Marsh and others, 1979) ____________________Geochemical distribution and

abundance of nickel, cobalt, 

lanthanum, and yttrium.

G (Marsh and others, 1978) __ ________ _________Geochemical distribution and

abundance of barium, arsenic, 

boron, and vanadium.

H (Marsh and others, 1979) ____________________Geochemical distribution and

abundance of antimony and 

niobium.

I (Marsh and Wiltse, 1979) ______________________Composite geochemical map.

J (Albert, LeCompte, Landsat image and interpretations, 

and Steele, 1978). ,

U.S. Geol. Survey Open-File Report OF-76-492 (O'Leary and others, 1976)_________Geochemical analyses and statistical data for stream sediment 

samples.

U.S. Geol. Survey Open-File Report OF-77-543 (Detra and others, 1977) Geochemical analyses and statistical data for heavy mineral 

concentrations and organic 

samples.

The Alyeska haul road is the only usable road 

into the quadrangle. It crosses into the Chandalar 

quadrangle at about the midpoint of the western 

boundary and follows the valley of the Middle Fork 

of the Koyukuk River and the Dietrich River to the 

northern boundary (fig. 3). The haul road extends 

to Prudhoe Bay to the north and to Livengood to 

the south, where it joins the public highway. 

Airstrips at Chandalar Lake and at the Dietrich 

Alyeska campsite (fig. 3) as well as the several 

larger lakes in the quadrangle afford access by 

multi-engine fixed wing aircraft. Winter trails and 

the now abandoned Beaver-Caro Road served in 

the past to meet the freighting needs of the gold 

miners.

MINERAL PRODUCTION AND 

EXPLORATION

With the exception of recent quarrying of roadbuilding materials, the only mineral production 

from the Chandalar quadrangle consists of gold 

and byproduct silver from lode and placer deposits 

in the area east of Chandalar Lake and from placer

deposits along tributaries of the Koyukuk River at 

the western edge of the quadrangle. References to 

these deposits are included in a summary of published reports on mineral occurrences in the quadrangle (Cobb, 1976). Gold placers were discovered 

in the Koyukuk region about 1885 and in the 

Chandalar Lake area in 1905 (Chipp, 1970, p. 

3-5). Placer mining was done by hand methods 

until the 1940's; after then, mechanical methods 

were used on some deposits. Gold production from 

the deposits in the Koyukuk-Chandalar district 

(which extends west into the Wiseman, Survey 

Pass, and Hughes quadrangles) has been estimated at 12 million g (380,000 troy oz) by Berg, 

Eberlein, and MacKevett (1964, p. 106). Gold production from placer deposits in the Chandalar 

Lake area has been estimated at 1.2 million g 

(40,000 troy oz) of which 400,000 g (14,000 troy oz) 

were recovered from Big Creek, primarily from 

mechanized operations since 1950 (Heiner and 

Wolff, 1968, p. 14). About one gram of silver was 

produced for every 7 grams of gold from placer 

deposits of the Chandalar district. Myrtle Creek
Pribilof' 

Islands/ PACIFIC OCEAN

rKodiakl

100

I

200 300 KILOMETERS 

I 

 

I 

100 200 MILES

FIGURE 1. Index map of Alaska showing location of Chandalar quadrangle (pattern).

has been one of the biggest gold producers in the 

Koyukuk mining district (Mulligan, 1974, p. 6). 

Some small placer operations are currently active.

Gold-quartz vein deposits in the Chandalar 

Lake area were identified in the early 1900's and 

some gold-silver ore was produced from underground workings at the Mikado, Little Squaw, and 

Summit mines. Since 1960, about 30,000 g (1,000 

troy oz) of gold and about 6,000 g (200 troy oz) of 

silver have been reported produced from the 

Mikado mine.

Recent exploration activity (as of 1977) is evidenced by a considerable amount of claim staking 

since 1969, especially in the Big Spruce CreekNorth Fork Chandalar River area (1969-1975), in 

the Geroe Creek area (1975-1977), and along the 

North Fork of the East Fork of the Chandalar

River (1976-1977). Exploration targets include 

porphyry copper and molybdenum deposits and 

contact metamorphic copper deposits.

Over 4 million cubic meters of sand, gravel, fill, 

and other road building materials have been quarried along the Koyukuk and Dietrich Rivers for 

use in the construction of the trans-Alaska 

pipeline and the pipeline road.

ACKNOWLEDGMENTS

The authors express their appreciation of the 

work of the scientists who pioneered topographic 

and geologic mapping of the Chandalar quadrangle (Schrader, 1900 and 1904; Maddren, 1913; 

Mertie, 1925); their work is incorporated in the 

present map and reports. Thanks are due to the 

Alyeska Pipeline Service Company and its per-
Eastern^ Brooks Range

| Porcupine 

Ptafeau

-----J 

Koikrine-hodzana Highlands i , Yuk6n Flats

4 - -T - I Action

0 5 10 15 20 25 KILOMETERS

[. rill I I I

I ' i ' ' i n r

0 5 10 15 MILES

FIGURE 2. Physiographic divisions of the Chandalar quadrangle.

sonnel for permitting refueling at construction 

campsites along the pipeline route, thus greatly 

improving the efficiency of our helicopter operations, and to local Alaskans whose helpful cooperation ranged from providing housing to providing 

details of local geological information. In particular, special thanks are due the late Wayne (Red) 

Adney prospector, guide, and homesteader of 

Chandalar Lake; Eskil Anderson and the late 

Frank Birch of Chandalar Mining and Milling 

Company; John Graham of Placid Oil Company, 

and Russell Babcock of Bear Creek Mining Company.

We are indebted to many people within the 

Geological Survey, especially to Betty Mclntire, 

who coped so ably with our logistic and supply 

problems, and Henry C. Berg, coordinator of AMRAP, who assisted throughout the project.

GEOLOGICAL INVESTIGATIONS

PREVIOUS GEOLOGICAL INVESTIGATIONS

Geological investigations in the Chandalar 

quadrangle began in 1899 when F. C. Schrader 

and T. G. Gerdine, topographer, made the first 

geologic and topographic map of the Koyukuk and
450 147'

0 10 20 KILOMETERS 

0 10 MILES

FIGURE 3. Index map showing Alyeska haul road and 

large airfields.

Chandalar area (Schrader, 1900,1904). In 1903, S. 

J. Marsh prospected along the eastern part of the 

quadrangle while traversing the Brooks Range. 

He provided a brief written report with a rough 

map to the U.S. Geological Survey. A. G. Maddren 

in 1909 made a detailed study of the gold placer 

occurrences of the Koyukuk and nearby parts of 

the Chandalar drainage (Maddren, 1913). J. B. 

Mertie (1925) refined and extended the mapping of 

the Chandalar mining district to essentially coincide with the present 3° quadrangle. Reports on 

gold occurrences, prospects, mining developments, 

and related geology have been made over the intervening years, at first by personnel of the Alaska 

Territory Department of Mines (Thompson, 1925; 

Reed, 1927,1929,1930,1938; Stanford, 1934), and 

after Alaska statehood by Saunders (1963) and 

Chipp (1970) of the Alaskan Department of Natural Resources, Division of Mines and Geology. 

Chipp's detailed study of the geology and geochemistry relating to the gold mineralization in 

the Chandalar mining district refined the stratigraphy and structural interpretation of the regional 

mapping.

RECENT STUDIES

The present study incorporates field and laboratory work started in 1959 and carried out intermittently to 1977. Helicopter-supported reconnaissance geologic mapping that started in August of 

1959 and concluded in the 1960 field season resulted in publication of a l:2,r>0,000-scale geologic 

map of the Chandalar quadrangle (Brosge and 

Reiser, 1964). In response to a national heavy 

metals investigation program in 1967, limited 

geochemical sampling and geologic mapping were 

carried out over an area which included part of 

the Chandalar quadrangle. Results of this work 

were published as U.S. Geological Survey Professional Paper (Brosge and Reiser, 1972).

In 1972 and 1973 aeromagnetic surveys of the 

western and eastern halves of the Chandalar 

quadrangle were flown under contract for the 

Geological Survey by Aeroservice and geoMetrics, 

and the aeromagnetic maps subsequently were released as separate sheets (U.S. Geol. Survey, 1973, 

1974). Regional gravity data were collected 

primarily during the summers of 1964 and 1972 as 

part of the effort to prepare the State gravity map 

(Barnes, 1977). The geology of a few small areas in 

the northern part of the quadrangle was remapped 

in 1974, 1975 and 1976 in the course of work in 

adjacent quadrangles (Dutro and others, 1976; 

Brosge and others, 1977). In 1975 a helicoptersupported field program directed by S. P. Marsh 

completed systematic geochemical reconnaissance 

sampling of the entire Chandalar quadrangle. 

Slightly more than 2,100 samples consisting of 

stream sediments, soil, heavy concentrates, vegetation, and rock were collected and analyzed. The 

analytical data have been placed on open file 

(O'Leary and others, 1976; Detra and others, 

1977). At the same time, detailed mapping and 

investigation of three of the mineral prospects was 

completed by M. A. Wiltse, who was affiliated with 

the Alaska Division of Geological and Geophysical 

Surveys, and samples were collected for K/Ar age 

determinations.

GEOLOGY OF THE CHANDALAR 

QUADRANGLE

The Chandalar quadrangle is underlain predominantly by low-grade metasedimentary rocks 

of Devonian and older age (fig. 4). The metamorphic facies represented in the Chandalar quadrangle are the greenschist facies and glaucophane 

schist facies of Turner and Verhoogen (1960) and 

the prehnite-pumpelleyite and hornblende 

hornfels facies as described by Hyndman (1972). 

Granitic rocks of several ages underlie about 15 

percent of the quadrangle. Numerous small bodies 

of mafic greenschist, greenstone, and slightly al-
0 5 10 15 20 25 KILOMETERS

11 ^ ^ i j i i i i

0 5 10 15 MILES

FIGURE 4. Metamorphic facies and K-Ar ages of rocks in the Chandalar quadrangle.

tered mafic volcanic rocks, as well as one small 

ultramafic body, occur in the quadrangle. Folding 

and faulting are complex; several thrust faults 

have been mapped, but the full extent of the 

thrusting is not known. Within the quadrangle the 

physiographic divisions correspond with three 

geologically distinct terranes.

The southern part of the quadrangle, coinciding 

with the Kokrine-Hodzana Highlands is mostly 

underlain by granodiorite, quartz monzonite, granite, and gneissic granite of Cretaceous age. Migmatite and thermally altered schist border these 

intrusives in discontinuous outcrop.

The Kobuk Trench, flanking the north side of 

the Kokrine-Hodzana Highlands, is for the most 

part a wide flat valley covered by surficial deposits. 

Slightly metamorphosed sedimentary rocks form 

subdued outcrops in small areas, but probably represent the major rock type underlying the lowland. 

The dominant outcrops are an ophiolitic assemblage of mafic volcanic rocks including pillow 

basalt, chert, some greenstone, and one ultramafic 

body. A narrow band of buried volcanic rocks 

aligned with the mafic outcrops is also indicated by 

the aeromagnetic studies. Both the sedimentary 

and volcanic rocks are metamorphosed to the

6
EXPLANATION

Unconsolidated surficial deposits

Rocks not metamorphosed

Prehnite-pumpellyite fades

Greenschist fades

Hornblende hornfels fades

Glaucophane schist facies, overprinted by 

hornblende hornfels facies

Ultramafic rocks

Granitic rocks

Migmatite

SYMBOLS

Geologic contact, approximately located; 

where contact separates metamorphic rock 

units, it indicates approximate location of a 

facies change

Radiometric age sample locality in granitic 

rocks, and ages determined for biotite (B), 

hornblende (H), and zircon (Z)

Radiometric age sample locality in thermally 

metamorphosed schist, and ages determined 

for biotite (B) and muscovite (M)

FIGURE 4. Continued.

prehnite-pumpellyite facies. The age of the metasedimentary rocks is uncertain, possibly Devonian; the volcanic rocks are probably not older 

than Mississippian or younger than Jurassic. The 

youngest rocks in the quadrangle are in the 

trench. Cretaceous polymictic conglomerates with 

interbedded gray wackes occur near the southwest 

corner and basalt flows of probable Tertiary age 

near the southeastern corner of the quadrangle. 

The mountainous terrane of the northern threefourths of the quadrangle comprising the eastern

Brooks Range and Porcupine Plateau physiographic sections is underlain by schist, phyllite, 

slate, limestone, marble, greenstone, and granitic 

intrusives. Generally the metasedimentary rocks 

belong to the low-grade greenschist facies, but 

somewhat higher grade metamorphosed rocks 

occur in T. 34 N., R. 2 W., where relict glaucophane 

in chloritized amphibole schist indicates a retrograded former glaucophane schist facies. The extent that the greenschist may have replaced 

former glaucophane schist facies elsewhere in the 

quadrangle is unknown (U.S. Geol. Survey, 1975). 

Contact aureoles of hornblende hornfels facies 

occur around the granitic intrusives. Biotitegarnet schist and tactite are the typical contact 

rocks of the northern plutons, whereas 

andalusite-staurolite-biotite schists are associated with the southeastern granitic body. Unmetamorphosed sedimentary rocks, consisting 

mostly of Mississippian limestone, shale, and conglomerate are exposed beneath Devonian rocks in 

a structural window in the northwest corner of the 

quadrangle.

Complex folding and thrust faulting are evident 

in the mountains north of the Kobuk Trench. The 

plate of Devonian rocks thrust over the 

Mississippian rocks has a minimum displacement 

of 18.5 km. A thrust plate of similar minimum 

displacement but involving pre-Mississippian 

schist is mapped in the vicinity of Chandalar Lake 

and is in turn overlain by another thrust plate 

containing calcareous schist and the northernmost 

granitic pluton. The Kobuk Trench itself may 

mark a major linear fault zone (Grantz, 1966); the 

volcanic rocks and chert within the trench have 

been interpreted to be oceanic rocks that have been 

obducted onto the continental crust represented by 

the Brooks Range (Patton and others, 1977).

POTASSIUM-ARGON AGES

Isotopic age determinations made prior to 

AMRAP on micas and zircons from one southern 

and one northern granitic pluton (Brosge and 

Reiser, 1964) are shown on figure 4. The micas 

from both plutons and the zircon from the southern pluton gave compatible ages, indicating a 

Middle Jurassic to middle-Cretaceous age. The 

zircon from the northern pluton, however, indicated a Late Devonian minimum age.

Recent K/Ar determinations for hornblende in a 

granodiorite collected at Big Spruce Creek indicate an Ordovician or older age (D.L. Turner and
M. L. Silberman, written commun., 1977). This 

new age determination makes uncertain the previously inferred Devonian age of the sequence of 

calcareous and quartz-muscovite schists apparently intruded by the granodiorite.

DESCRIPTION OF COMPONENT MAPS OF 

THE CHANDALAR QUADRANGLE FOLIO

GEOLOGY (MAP 1-375)

The multicolored geologic map of the Chandalar quadrangle at 1:250,000 scale (Brosge and 

Reiser, 1964) is based on the reconnaissance 

mapping done in 1959 and 1960. In the course of 

the 1975 and 1976 AMRAP studies some additional mapping was done, but not enough to 

warrant publication of a revised geologic map. 

Detailed maps of three copper prospects in the 

quadrangle are included in the folio (Marsh and 

Wiltse, 1979). Other new information obtained 

since 1960 by the U.S. Geological Survey and the 

Alaska Division of Geological and Geophysical 

Surveys has been combined with the previous 

mapping in the compilation of a generalized 

geologic map which is used as the base for the 

maps in the Chandalar AMRAP folio. Revised 

parts of the generalized geologic map that incorporate this new information are outlined on figure 

5, and they are reproduced in this circular as

68'

150° 147°

67°

Fig. 6 Fig. 7

Fig. 8

FIGURE 5. Localities where the geologic map of the Chandalar quadrangle (Brosgg and Reiser, 1964) has been revised in 

the compilation of the generalized geologic map for the 

AMRAP folio.

figures 6 to 11, with the revised contacts, faults, 

or map unit symbols shown by full black lines. 

The revised correlation and description of the 

generalized map units is shown as figure 12. The 

more significant revisions of the mapping, 

stratigraphic nomenclature, and age assignments 

are described below.

REVISIONS OF MAP 1-375 

MAPPING

Most of the slate and phyllite exposed beneath 

the Lisburne Group in the northwest corner of the 

quadrangle (fig. 6) was originally mapped as the 

Devonian Hunt Fork Shale and as Mississippian 

Kayak Shale. The rocks in this small area have 

since been recognized as part of a phyllite unit of 

probable Cambrian or Ordovician age that crops 

out extensively farther west (Dutro and others, 

1976). Because of their small area they are here 

included in the undifferentiated Paleozoic and 

Mesozoic(?) phyllite unit. Some mafic sills and a 

pillow basalt flow in the northcentral and northeast parts of the quadrangle that were not recognized in the original mapping have been added to 

the present map (figs. 7 and 8). In addition, the 

contacts of the Hunt Fork Shale and of the Skajit 

Limestone have been revised at several places 

along the northern edge of the quadrangle (figs. 6, 

7, and 8). At Big Spruce Creek in the west-central 

part of the quadrangle a sill of hornblende 

granodiorite has been added to the map within an 

area previously mapped as tactite (fig. 9). This sill 

is shown in more detail on the map of the Venus 

prospect by M. A. Wiltse (Marsh and Wiltse, 

1979). In the central part of the quadrangle (fig. 

10) the areas of tactite north of Squaw Lake and 

of greenstone and greenschist south of Squaw 

Lake are smaller than originally shown. The flat 

thrust faults that dip beneath the Chandalar gold 

mining area from the north and from the south 

have been relocated to conform to the detailed 

mapping by Chipp (1970), and a few high-angle 

faults have been added.

In the southwest part of the quadrangle (fig. 11) 

a small body of serpentinite that was previously 

mapped as volcanic rocks has been separately 

mapped as ultramafic.

NOMENCLATURE

Quartz pebble conglomerate (Cretaceous). The 

name "Bergman group" used on map 1-375 has

8
149° 30'

10 KILOMETERS

_I

5 MILES

FIGURE 6. Revisions of the northwest part of the geologic map of Chandalar 

quadrangle (Brosge and Reiser, 1964).

148° 30' 148° 00'

5 MILES

FIGURE 7. Revisions of north-central part of geologic map of Chandalar quadrangle (Brosge and Reiser, 1964).

been abandoned (Patton, 1973) and has been replaced by informal descriptive terms for these 

rocks in the adjacent Wiseman and Bettles quadrangles (Patton and Miller, 1973).

Hunt Fork Shale (Upper Devonian). The Hunt 

Fork Shale has been mapped continuously from 

its type area in the Killik River quadrangle 

(Chapman and others, 1964) to the Chandalar 

quadrangle. The term "slate and sandstone" used 

on map 1-375 has therefore been replaced by the 

name Hunt Fork Shale on the generalized map. 

As outlined, the lower part of the Hunt Fork 

Shale as generalized includes some thin interbedded reefs that were previously mapped as "Skajit 

Limestone." It also includes some brownweathering shale that occurs locally below the 

horizon of these reefs and that has now been recognized in the adjacent Philip Smith Mountains 

quadrangle as the upper part of a newly recognized unnamed Upper Devonian formation that is 

in part coeval with the Hunt Fork (Brosge and 

others, 1977; Dutro and others, 1977). The basal 

conglomerate of the "slate and sandstone" unit 

that was differentiated in a few places on map 

1-375 may also be equivalent to the upper part of 

this new formation. The rocks equivalent to the 

lower part of the new formation are mapped separately as the purple and green slate and phyllite 

unit and the limestone and siltstone unit which 

underlie the Hunt Fork.
147° 30'

5 MILES

FIGURE 8. Revisions of northeast part of geologic map of Chandalar quadrangle (Brosge and Reiser, 1964).

149° 30'

10 KILOMETERS

0 5 MILES

FIGURE 9. Revision of west-central part of geologic map of 

Chandalar quadrangle (Brosge and Reiser, 1964).

AGE ASSIGNMENTS

Lisburne Group (Pennsylvanian and Mississippiari) and Kayak Shale (Mississippian). 

New collections of fossils from the Wiseman 

quadrangle show that the Lisburne Group about 

25 km west along strike from the Lisburne in the 

northwest corner of the Chandalar quadrangle

includes Pennsylvanian as well as Mississippian 

limestone (Armstrong and others, 1976). 

Fieldwork in that area has also shown that the 

thin conglomerate at the base of the Kayak Shale 

is part of the Mississippian, and not the Devonian 

Kanayut Conglomerate as it was shown on map 

1-375. Therefore the Kanayut Conglomerate has 

been deleted from the map, and the age of the 

Lisburne has been revised to Pennsylvanian and 

Mississippian, although it is not known that beds 

as young as Pennsylvanian are actually preserved in the small area of Lisburne outcrop 

within the Chandalar quadrangle.

Skajit Limestone (Silurian to Upper 

Devonian). The age of the Skajit Limestone recently has been revised to Silurian and Devonian 

on the basis of Silurian brachiopods found in the 

western Brooks Range (Oliver and others, 1975, 

p. 27 and fig. 12). This revision has been confirmed by the discovery of Silurian brachiopods in 

limestone boulders in the stream that bisects the 

large anticlinal exposure of the Skajit in the 

northeast corner of the Chandalar quadrangle (J. 

T. Dutro, Jr., written commun., 1977).

Granitic rocks (Mesozoic and older). The 

granitic rocks were assigned a Mesozoic or late 

Paleozoic age on map 1-375. Micas from two of the 

plutons gave K/Ar ages of 101 to 125 m.y. (Early

10
148° 30" 148° 00'

10 KILOMETERS

5 MILES

FIGURE 10. Revisions of central part of geologic map of Chandalar quadrangle (Brosg6 and Reiser, 1964).

Cretaceous), while zircons from the same localities gave a confirmatory Pb/alpha age of 140 

m.y. (latest Jurassic or earliest Cretacous) for the 

Hodzana pluton in the southwest part of the 

quadrangle and a discordant Pb/alpha age of 380 

m.y. (Devonian) for the Baby Creek pluton west of 

Chandalar Lake (see fig. 4). No mineral ages were 

measured for the Geroe Creek pluton.

A Cretaceous age for emplacement of the Hodzana pluton is probably correct. The analytical

age of the zircons agrees fairly well with that of 

the biotite, and the pluton contains mafic 

schlieren and small roof pendants which suggests 

that the granite has intruded part of the adjacent 

Mississippian to Jurassic volcanic rocks. This pluton appears to be one of the many closely spaced 

Cretaceous plutons that have invaded the schist 

of the Kokrine-Hodzana Highlands (Patton and 

Miller, 1973; Brosge and others, 1973). However, 

recent analyses of hornblende indicate that at

11
149° 30'

1O KILOMETERS

5 MILES

FIGURE 11. Revision of southwest part of geologic map of 

Chandalar quadrangle (Brosge and Reiser, 1964).

least some of the granitic rocks in the northern 

part of the quadrangle are Ordovician or older.

During his 1975 mapping of the Venus prospect 

on Big Spruce Creek, M. A. Wiltse sampled a 

small, previously unmapped sill of partly 

metamorphosed hornblende granodiorite 

porphyry similar to that in some of the larger 

bodies of "gneissic granitic rocks" previously 

mapped northeast of Big Spruce Creek and along 

the northern margin of the Geroe Creek pluton. 

Replicate samples of hornblende and of partially 

chloritized and sericitized hornblende from the 

sill on Big Spruce Creek have been analyzed by D. 

L. Turner and M. L. Silberman (written commun., 

1977). The average K/Ar ages determined were 

286 m.y. (Permian) for the partially chloritized 

hornblende and 486 m.y. (Ordovician) for the 

purer samples of hornblende. These analytical 

ages appear to be reliable; however, some uncertainty remains about the age of these granitic 

rocks because Wiltse also found two small bodies 

of sheared granodiorite in the Skajit Limestone at 

the Gayle prospect (Marsh and Wiltse 1979), 

where the Skajit contains brachiopods of Devonian or Silurian age. Because of this uncertainty 

the granitic rocks in the northern part of the 

quadrangle are not assigned to any specific part of 

the Paleozoic, and the generalized unit of all 

granitic rocks is shown as Mesozoic and older.

Mafic rocks and chert (Mississippian to 

Jurassic). On map 1-375 the unmetamorphosed 

volcanic rocks and chert in the southern part of 

the quadrangle were considered to be Late Devon-

) in age, although a note was added just before publication that similar rocks in the adjacent 

Christian quadrangle are Carboniferous or 

younger in age. The volcanic rocks and chert of 

this southern belt have recently been assigned a 

Jurassic to Permian age (Patton and Miller, 1973) 

on the basis of Permian fossils found in the Wiseman quadrangle and Jurassic K/Ar dates on mafic 

rocks in the Christian quadrangle. The whole 

suite of volcanic rocks, ultramafic rocks, and chert 

around the Koyukuk Basin has more recently 

been assigned a Mississippian to Jurassic age 

(Patton and others, 1977), and this age has been 

shown for those rocks in the generalized map of 

the Chandalar quadrangle.

Greenstone and greenschist; hornblende schist 

(Mesozoic(?) and Paleozoic). Metamorphosed 

mafic rocks in the central and northern parts of 

the quadrangle were assigned a probable Devonian age on map 1-375 and were considered to be 

probably age equivalents to the volcanic rocks in 

the southern part of the quadrangle. Inasmuch as 

the volcanic rocks are now thought to be 

Mississippian to Jurassic, some of the 

metamorphosed mafic rocks may be as young as 

Jurassic. However, many of the mafic rocks in the 

northern part of the quadrangle are probably Devonian. Recent fieldwork has shown that part of 

the tabular body in the Hunt Fork Shale along 

the north edge of the quadrangle at longitude 

148° (fig. 7) is a pillowed flow, rather than a sill 

and that a few more flows occur in the Devonian 

shale north of the quadrangle (Brosge and others, 

1977). In addition, a K/Ar age of 363±11 m.y. 

(Devonian) has been measured for albite from a 

gabbro sill that intrudes the Hunt Fork 33 km 

north of the Chandalar quadrangle (M. L. Silberman, written commun., 1977). The generalized 

unit of metamorphosed mafic rocks and the unit of 

thermally metamorphosed mafic rocks are therefore shown as Mesozoic(?) and Paleozoic in age.

Quartz-muscovite schist; garnet-mica schist; 

biotite-staurolite schist; calcareous schist and 

marble; feldspathic chloritic schist; chloritized 

amphibole schist (Paleozoic or older). The schist 

units were previously assigned a Devonian age, 

but new radiometric dates indicate that the protolith of the schist may be early Paleozoic or Precambrian image. On map 1-375 each of the schist 

units was correlated with a less metamorphosed 

Devonian unit of similar composition. The pelitic 

quartz-muscovite schist was correlated with the

12
Hunt Fork Shale, and the calcareous schist with 

the limestone and siltstone unit. This lithologic 

correlation is supported by the apparent geographical and structural continuity between each 

of the schist units and its presumed Devonian 

counterpart where these units cross the axis of 

the large anticlinorium that plunges northeastward from the granite near Chandalar Lake. The 

calcareous schist crops out on the axis of this anticlinorium on the west side of the Middle Fork of 

the Chandalar River, while just across the river, 

the slightly less metamorphosed limestone and 

siltstone unit crops out on the axis (fig. 13). The 

structural continuity of the calcareous schist with 

the limestone and siltstone unit at this place is 

evident from the continuity of a long linear magnetic anomaly that follows the strike of the calcareous schist along the anticlinorium for about 

40 km and continues on eastward into the area of 

limestone and siltstone (Cady, 1978). The Hunt 

Fork Shale overlies the limestone and siltstone 

and also some of the calcareous schist on the axis 

of the anticlinorium and extends southward to the 

area of quartz-muscovite schist on the south 

flank. Since all the rocks involved have been regionally metamorphosed to greenschist facies, the 

geographic relations suggest that the wellfoliated schist units simply grade northeastward 

into the less metamorphosed bedded Devonian 

rocks.

A post-Devonian, probably Cretaceous age for 

this regional metamorphism can be inferred from 

the metamorphism of the fossiliferous Devonian 

rocks, from the presence of schist clasts in the 

Cretaceous conglomerate, and from the Cretaceous radiometric dates of micas in the Baby 

Creek pluton and adjacent schist. However, recent radiometric dating by D. L. Turner of 

glaucophane, paragonite, and actinolite from 

schist in the western Brooks Range gives evidence that two other metamorphic events preceded the Cretaceous granitic intrusions a late 

Precambrian blueschist event (Forbes and others, 

1977) and a Triassic event that retrograded the 

blueschist (Alaska Division of Geological and 

Geophysical Surveys, 1973, p. 27-30, 34-36). The 

schist in the Chandalar quadrangle probably has 

a metamorphic history similar to the schist in the 

western Brooks Range because the schist belt is 

continuous between the two places and because 

the chloritized amphibole schist in the Chandalar 

area is at least in part retrograded glaucophane

schist. This, these new radiometric data would 

indicate that the schist is Precambrian. A Precambrian or early Paleozoic age of the schist is 

also indicated by the Ordovician K/Ar age of the 

granodiorite that intrudes the calcareous schist 

on Big Spruce Creek.

The Precambrian or early Paleozoic age of the 

schist is not certain, however, because both of the 

lines of evidence based on radiometric ages seem 

to be in conflict with paleontologic data. The 

blueschist facies terrane in the western Brooks 

Range includes beds of marble that contain 

Paleozoic (probably Devonian) fossils (Alaska Division of Geological and Geophysical Surveys, 

1973, p. 28). At the copper prospects of the Chandalar area small bodies of granodiorite occur in 

fossiliferous Devonian or Silurian limestone as 

well as in the calcareous schist where the dated 

granodiorite sample was obtained. These apparent conflicts have several possible solutions, but 

since they are not resolved, an indefinite age has 

been assigned to the schist.

Relations between the Hunt Fork Shale and the 

schists can be interpreted to fit either a Precambrian or a Devonian age of the schist protolith 

because there is a regional unconformity beneath 

the Hunt Fork. The Hunt Fork contains a basal 

conglomerate in many places and rests unconformably (Brosge and Dutro, 1973) on the Skajit 

Limestone and on several Devonian units 

younger than the Skajit. If the schists are Precambrian, the Hunt Fork was probably deposited 

unconformably upon them. On the east side of the 

Middle Fork of the Chandalar the basal conglomerate of the Hunt Fork rests on the moderately 

metamorphosed calcareous rocks of presumed 

Devonian age that are the lateral equivalents of 

the calcareous schist unit (see fig. 13). If the schist 

is Precambrian these less metamorphosed rocks 

must also be part of the Precambrian rather than 

part of the Devonian limestone and siltstone unit, 

and the basal contact of the Hunt Fork at this 

place is a profound unconformity rather than a 

minor one. The contact of the Hunt Fork with the 

calcareous schist and the feldspathic schist units 

west of the Middle Fork might also be such an 

unconformity, although the basal conglomerate 

was not found in that area. The nature of the contact between the Hunt Fork and the quartzmuscovite schist unit is uncertain in the two 

places where it has been mapped, partly because 

of poor exposures and partly because of the diffi13
EXPLANATION

Geology generalized and revised from Brosge and Reiser (1964) and Qiipp (1970)

CORRELATION OF MAP UNITS

SURFICIAL DEPOSITS

J QUATERNARY

FOSSILIFEROUS, PARTLY METAMORPHOSED 

SEDIMENTARY ROCKS METAMORPHIC, INTRUSIVE, AND V

Unconformity

Unconformity

CRETACEOUS

PENNSYLVANIAN 

] AND 

J MISSISSIPPIAN

Dpsa

DCS

Dls

DSsk

> DEVONIAN

DEVONIAN AND 

SILURIAN

gs

ph

hs

cfs

csmm

fcs

MESOZOIC(?)

AND 

PALEOZOIC

PALEOZOIC 

OR OLDER

mig

:(?)

1C

[C 

R

gr
DESCRIPTION OF MAP UNITS

IPMls

Dhf

Dps

This map is generalized from Brosge and Reiser (1964). Many of these map units 

are combinations of units shown separately on the older map. The Devonian and 

Devonian(?) age that was assigned to the metamorphic rocks by Brosge and Reiser 

(1964) is herein revised to early Paleozoic or older.

SURFICIAL DEPOSITS

Unconsolidated sedimentary deposits (Quaternary)

FOSSILIFEROUS PARTLY METAMORPHOSED 

SEDIMENTARY ROCKS

Quartz pebble conglomerate (Cretaceous)

Lisburne Group (Pennsylvania!! and Mississippian) and Kayak Shale 

(Mississippian)-Limestone, dolomite, shale, and conglomerate

Hunt Fork Shale (Upper Devonian) Slate and phyllite

Purple and green slate and phyllite (Devonian)

Purple and green andesitic volcanic sheared conglomerate (Devonian)

Chloritic siltstone and grit (Devonian)-Schistose; in part graywacke

Limestone and siltstone (Upper Devonian)-Schistose; includes some 

green slate locally

Skajit Limestone (Upper and Middle Devonian and Upper 

Silurian)-Limestone, dolomite, and marble

METAMORPHIC, INTRUSIVE, AND VOLCANIC ROCKS

Vesicular olivine basalt flows (Tertiary?)

Migmatite-Intercalated mica schist and granite; granite with mafic 

inclusions

Granitic rocks K/Ar dates of biotite are 101 m.y. and 125 m.y. 

(Brosge and Reiser, 1964); of hornblende, 486 m.y. (M.L. 

Silberman and D.L. Turner, written commun., 1977)

Dpsa

DCS

Dls

DSsk

ch

umf

hs

ph

qms

gms

bss

cfs

fcs

Mafic rocks and chert-P

diabase and gabbro. C

Ultramafic rocks

Greenstone and greensc

Shale (Dhf) in northe

Hornblende schist Most

Phyllite and schistose w

Quartz muscovite schist

Garnet mica schist-Mos

Biotite staurolite schist 

Calcareous schist, marble

Undifferentiated calcare

schist (fcs)

Feldspathic chloritic sch

quartzite

Chloritized amphibole sc

GE

Contact-Dashed where 

Normal fault-Dashed w

dotted where concea

Thrust fault-Queried wh

Sawteeth on upper p

FIGURE 12. Correlation and description of the map units shown on the generalized geologic map of the C
0 5 10 15 20 25 KILOMETERS

KM',', i I h ' H

10 15 MILES

FIGURE 13. Generalized geologic map of northern part of Chandalar quadrangle showing the possibly unconformable relation 

of the Upper Devonian Hunt Fork Shale to the older Paleozoic sedimentary rocks, to the schist, and to the calcareous rocks 

that are equivalent to part of the schist.

culty in distinguishing the more phyllitic phases 

of the Hunt Fork from some of the phyllitic 

schists.

SURFICIAL GEOLOGIC MAP (MAP MF-878-A)

Initial fieldwork along the Dietrich River and 

the Middle Fork of the Koyukuk River was carried out in connection with trans-Alaska pipeline 

activities in 1969-1971, and the entire Chandalar 

quadrangle subsequently was covered by ground 

and helicopter traverses during 1975 and 1976.

Able field and office assistance was provided by 

Robert M. Thorson during 1975 and 1976 and by 

James P. McCalpin during 1976 and 1977.

The surficial geologic map of the Chandalar 

quadrangle is based on (1) surface observations of 

morphology and composition of unconsolidated 

deposits, (2) examination of test pits, trenches, 

road cuts, and other shallow excavations, (3) 

stratigraphic study of bluff exposures, and (4) 

analyses of maps and drill logs prepared by U.S. 

Geological Survey personnel and Alyeska consul16
EXPLANATION

Unconsolidated Quaternary deposits

Mostly Mississippian sedimentary rocks 

Hunt Fork Shale (Upper Devonian)

Undivided Paleozoic sedimentary rocks older 

than the Hunt Fork Shale

Calcareous rocks mapped as probably the 

Devonian limestone and siltstone unit that 

occurs in unit (Pzs). These rocks are also 

equivalent to the calcareous schist unit in 

the lower part of the undivided schist and 

granitic rocks

Undivided schist and granitic rocks

SYMBOLS 

Geologic contact, includes some faults

 Contact of base of Hunt Fork Shale on older

rocks. Dashed where doubtful; dotted where 

concealed

Thrust fault contact of Hunt Fork Shale. 

Sawteeth on upper plate

Axis of anticlinorium, showing direction of 

plunge

FIGURE 13. Continued.

tants for the corridor occupied by the transAlaska pipeline (see map MF-878-B). Placement 

of glacial deposits within the standard central 

Brooks Range stratigraphic sequence was based 

on similarities in position, extent, and postglacial 

modification to Anaktuvuk, Sagavanirktok, Itkillik, and Echooka drift sheets at type localities 

designated by Detterman, Bowsher, and Dutro 

(1958) and on subsequent correlations by 

Williams (1962), Hamilton (1969), and Hamilton 

and Porter (1975). Drift nomenclature has been 

revised in accordance with the recommendations 

of Keroher and others (1966) and Hamilton and 

Porter (1975). The former Anaktuvuk and 

Sagavanirktok glacial advances and deposits are 

currently termed Anaktuvuk River and

Sagavanirktok River to avoid conflict with previously named rock units (Keroher and others, 

1966, p. 91 and 3379; Sable, 1977, p. 24-30). Itkillik and Echooka are replaced by Itkillik I, Itkillik 

II, and late Itkillik, which correspond to the drift 

sequence described and illustrated by Hamilton 

and Porter (1975).

Surficial geology of the Chandalar quadrangle 

is dominated by the effects of successive episodes 

of Pleistocene valley-glacier activity which deeply 

scoured mountain passes and valley systems and 

deposited vast quantities of drift and outwash at 

and beyond the south flank of the Brooks Range. 

Glacier erosion oversteepened the walls of 

mountain valleys, creating unstable rock faces 

subject to falls, slides, and flows of rock and debris 

and to the accumulation of talus rubble (tr) and of 

landslide (Is) and flow-slide (fl) deposits. Glacier 

retreat from massive end moraines near the south 

flank of the range left extensive closed basins 

(stippled pattern) which received thick deposits of 

lacustrine sediment (1), alluvium (al), fluvial and 

eolian sand (sa), and fan delta sediment (fd) at the 

mouths of tributary streams. The older glacial 

deposits generally are more weathered, more dissected by stream erosion, and often bear relatively thick blankets of ice-rich, frozen silt and 

muck. Younger deposits are less altered by postglacial processes and hence provide more suitable 

and readily accessible construction materials.

The oldest glacial deposits, presumably of the 

Anaktuvuk River Glaciation (ad), consist of 

highly eroded and fragmentary weathered drift 

patches and erratics beyond the limits of later ice 

advances in Funchion Valley and the main valley 

of the Chandalar. Outwash related to this advance forms terraces incised within older preglacial terrace gravel (Tpt). During the subsequent 

Sagavanirktok River Glaciation, large valley 

glaciers flowed south through the Brooks Range 

along the Chandalar and Koyukuk drainage systems (Williams, 1962) and coalesced with one or 

more smaller ice tongues that originated in unnamed highlands south of the range. The coalescent piedment glacier complex deposited an extensive drift sheet (sd) within the broad structural trough presently occupied by the South Fork 

of the Koyukuk River and the West Fork and 

trunk stream of the Chandalar system. Ice flowed 

eastward nearly to the southeast corner of the 

Chandalar quadrangle and westward beyond the 

quadrangle's western boundary. Drift deposited

17
during the subsequent Itkillik Glaciation (id:) 

defines a piedmont lobe formed by the coalescence 

of glaciers at the mouths of the Koyukuk's South 

Fork and the Chandalar's North Fork (Williams, 

1962). Less extensive glaciers farther east deposited individual drift sheets within the Brooks 

Range and at its southern flank. Itkillik II deposits (id2, io2 , and ik), which formed within the main 

forks of the Chandalar Valley and the South Fork 

of the Koyukuk Valley (Williams, 1962), include 

extensive ice-contact gravel and outwash deposits 

and generally lack significant cover of ice-rich or 

organic silt. These deposits provide particularly 

well drained and stable surfaces and abundant 

borrow materials. Late Itkillik deposits (id3 and 

io3), which generally occur in tributary valleys, 

consist largely of poorly sorted till, fine-grained 

glaciolacustrine sediments, and outwash overlying lake beds.

Holocene glaciation has been restricted to relatively high altitudes predominantly in a 25-kmwide belt centered on the Continental Divide 

(Hamilton, 1977), and only a few small drift 

bodies (nd, ndi, and nd2) are present in the Chandalar quadrangle. Rock glaciers are more abundant and widespread. They occur to altitudes as 

low as 600 m (2,000 ft) along the South Fork of the 

Koyukuk and at altitudes of 900 m (3,000 ft) and 

above along tributaries to the Chandalar's North 

Fork. Rock glaciers formed from talus cones and 

aprons along valley sides are most abundant, but 

many others occupy abandoned cirques at valley 

heads. Additional Holocene deposits include 

beach deposits (b) along lake shores, solifluction 

sheets and aprons (s) on slopes, alluvium (al) 

along valley centers, and fans (f) at the mouths of 

tributary streams. Many of these deposits are 

much more abundant than indicated on the map, 

because the scale is too small to show alluvium 

along smaller tributary valleys, minor beach deposits, and small or thin sheets of talus and solifluction debris.

With the exception of sediments beneath the 

larger rivers and lakes, all surficial deposits of the 

Chandalar quadrangle are perennially frozen. 

Permafrost lies at shallow depth (0.2 to 1 m) beneath poorly drained or well insulated surfaces 

such as peat and organic silt; its depth is greater 

and more variable (1-5 m) beneath more opentextured deposits such as sand, gravel, and rock 

rubble.

Radiocarbon dates from the central Brooks

Range have been discussed by Hamilton and 

Porter (1975). We concluded that the Itkillik I ice 

advance was broadly contemporaneous with the 

Late Wisconsin advance of the Laurentide ice 

sheet, that the Itkillik II readvance probably occurred about 14,000 14 C yr B.P., and that late 

Itkillik fluctuations may represent individual 

events that terminated by 10,000 yr B.P. or earlier. More recent preliminary radiocarbon dates 

from the Koyukuk and Chandalar Valleys suggest that initial deposition of Itkillik I drift may 

have occurred more than 30,000 14 C yr B.P. and 

that this ice advance may be older than previously believed. Dating and identification of peat 

and wood specimens collected in the Chandalar 

quadrangle during 1975 and 1976 are now in 

progress, and results will be published when they 

are available. Since publication of the surficial 

geologic map (MF-878-A), seven radiocarbon 

dates have become available for the Chandalar 

quadrangle; dates and measured sections were 

published by Hamilton (1979).

MINERAL RESOURCES MAP (MAP MF-878-B)

The locations of mines, prospects, and mineral 

occurrences and favorable areas for the occurrence of mineral deposits are shown on the mineral resources map and described in the tables 

accompanying the map. In addition, the resource 

potential of the principal mineral commodities is 

discussed, and, where possible, quantitative estimates are made of resource potential. The assessments of favorable areas have been made 

with respect to the possible existence of mineral 

deposits within an area. The probability of discovery of existing mineral deposits is contingent 

upon the intensity of search effort and the effectiveness of the methods used and is not considered 

in this evaluation. The terminology used in discussing mineral resources has been jointly 

adopted by the Bureau of Mines and the Geological Survey (U.S. Bur. Mines and U.S. Geol. Survey, 1976).

Mineral resource potential areas have been 

selected on the basis of information about known 

deposits, combined with geologic, geophysical, 

geochemical, and earth satellite data presented in 

other components of the Chandalar quadrangle 

folio. The particular criteria used to delineate 

each area are listed on the map sheet. In some 

areas, mineral deposits of the specified type(s) are 

known to exist. Other areas, although not known

18
to contain mineral deposits, are considered permissible for the occurrence of some type(s) of mineral deposits because of geology and exploration 

history. The concept of geologic permissibility 

was proposed by Lasky (1947, p. 3) to consider the 

question of "Could ore be here?" in contrast to the 

concept of geologic probability "Should ore be 

here?" In this report, areas are considered to be 

permissible for the occurrence of deposits of a 

specified type if they have not been explored to 

the extent that any undetected mineral deposits 

would have already been discovered, and if they 

contain specific indicators of the deposit type such 

as characteristic alteration, geochemical 

anomalies, or related types of mineralization, or 

they contain geologic units, relations, or environments similar to those of areas that are known 

to contain deposits of the type under consideration.

The boundaries of the mineral resource areas 

have been determined with the assistance of the 

authors of the component maps of this study with 

final responsibility resting on the author of the 

mineral resources map. The relationship between 

geologic environments and various types of mineral deposits as described in Brobst and Pratt 

(1973) was used in considering the limits of a favorable area. The report of Boyle (1974) was of 

valuable assistance in interpreting the relationship between geochemical information and possible deposit types. The interpretation of 

aeromagnetic data provided some indication of 

subsurface structure and plutons. Although circular and linear features interpreted from earth 

satellite imagery were not a primary consideration in delineating any of the areas, the coincidence of these features with mineral resource 

potential areas has been noted on the mineral resources map in order to provide a basis for possible future applications of this technology to mineral resource appraisal.

The possibility exists that areas designated as 

favorable may not contain deposits and that areas 

not commented upon may contain deposits. This 

is of particular importance in areas where bedrock exposure is poor, such as along the Middle 

Fork of the Chandalar River. Despite this limitation, the mineral resource assessment provides 

usable information for decisionmakers in government and industry.

Seven types of deposits have been described as 

favorable within the selected areas. Examples of

four of these types have been observed: placer 

gold deposits, vein-type gold deposits, contactmetamorphic copper bodies, and porphyry copper 

or molybdenum deposits. Although strata-bound 

base metal deposits in sedimentary rocks, massive sulfide deposits in volcanic rocks, and rareearth deposits associated with pegmatitic rocks 

have not been found, these types of deposits occur 

elsewhere in similar geologic environments to 

those of the areas in the Chandalar quadrangle 

and may occur in the areas designated on the 

mineral resources map.

AEROMAGNETIC MAP AND INTERPRETATION (MAP 

MF-878-C, 2 SHEETS)

The western and eastern halves of the 

aeromagnetic map (sheet 1) and of the Chandalar 

quadrangle were flown separately and were released as open-file reports by the U.S. Geological 

Survey in 1973 (western half) and 1974 (eastern 

half). Regional trends calculated from the International Geomagnetic Reference Field were removed from both maps, but a difference in datums 

prevented connecting the contour lines across the 

join. Very complex variations of the magnetic 

field in the Chandalar quadrangle indicate 

significant variations in magnetite content of 

rocks exposed at the surface and also buried at 

depth.

The interpretive map (sheet 2) identifies magnetic rock units, many of which differ in their 

distribution from mapped geologic formations.

Among the rock units delineated by highs on 

the aeromagnetic map are an anticline of 

contact-metamorphosed calc-mica schist; a highly 

complex and variable band of quartz-muscovite 

schist; volcanic rocks associated with the Kobuk 

Trench; and granitic plutons south of the Kobuk 

Trench. In contrast to those south of the trench, 

granitic rocks north of the Kobuk Trench are 

nonmagnetic. Magnetic mapping may help to delineate copper, molybdenum, lead, and zinc deposits associated with the magnetic calc-mica schist 

and nonmagnetic granite and limestone. Detailed 

magnetic mapping may be useful in delineating 

faults in the quartz-muscovite schist which may 

contain gold-bearing veins. Two magnetic lows 

may mark nonmagnetic, possibly mineralized 

shear zones or alteration zones in the quartzmuscovite schist.

19
GEOCHEMICAL MAPS (MAPS MF-878-D to I)

The distribution and abundance of selected 

elements as obtained from stream sediment samples are shown on a series of geochemical maps. 

These elements were selected on the basis of their 

potential economic importance, their ranges of 

concentrations, or on their importance as 

geochemical pathfinders to economic deposits. 

The geochemical data are plotted on a screened 

base map showing the generalized geology, topography, and sample localities. Values of the 

selected elements are shown by map symbols, and 

the ranges of values are indicated on accompanying histograms. Statistical data are shown along 

with a perspective plot of each element. The 

geochemical maps show the results of minus 80 

mesh (177 micrometers) stream sediment samples. Panned concentrates, rock, and vegetation 

samples were also taken and have been used in 

the mineral resource evaluation. Raw geochemical data as well as an explanation of sampling, 

preparation, and analytical procedures of all 

samples are given in U.S. Geol. Survey Open-File 

Report OF-76-492 (O'Leary and others, 1976) 

and in U.S. Geol. Survey Open-File Report OF77-543 (Detra and others, 1977). The minus 80- 

mesh (177 micrometers) stream sediment 

medium was used in this study because of the 

regional setting in the north-central Brooks 

Range. The study area is one of generally high 

relief with short, fast moving streams and broad 

glacial valleys. All samples were taken from active streams, as close to the center channel as 

possible. All sediments were considered to be locally derived. Care was taken, when sampling an 

obviously glaciated terrane, to sample above or 

upstream from morainal material, wherever possible. Most samples were taken in areas where 

bedrock was within 30 meters of the sample site. 

The minus 80-mesh (177 micrometers) stream 

sediment has proved to be the most effective 

medium where clastic sediments are being derived from local bedrock (Foster and others, 

1976). Stream sediment samples were air dried 

and prepared by shaking through an 80-mesh 

(177 micrometers) stainless steel sieve. The 

minus 80-mesh (177 micrometers) fraction was 

saved for analysis. The samples were analyzed by 

a six-step, DC-arc semiquantitative spectrographic method described by Grimes and Marranzino (1968) for the analysis of geologic material. 

Owing to the high limits of determination for zinc

(200 parts per million) by the semiquantitative 

spectrographic method, all samples were 

analyzed for zinc by atomic absorption methods 

described by Ward, Lakin, Canney, and Van 

Sickle (1969).

Because of previous work done (Chipp, 1970; 

Brosge and Reiser, 1972; Mertie, 1925; Reed, 

1927; Stanford, 1934; Thompson, 1925) no sampling was done in the gold district in the central 

part of the quadrangle, although geochemical 

data from previous work are included (Brosge and 

Reiser, 1972).

A composite geochemical map showing major 

alteration zones and detailed geologic maps of 

selected mineral prospects are shown in a 

geochemical interpretation map.

INTERPRETATION OF LANDSAT IMAGERY

(MF-878-J, 2 sheets)

By NAIRN R. D. ALBERT

Interpretations of Landsat data were made on 

(1) a black and white Landsat mosaic (band 7) of 

the State of Alaska compiled by the U.S. Department of Agriculture and (2) computer-enhanced 

black and white and color Landsat imagery processed by the U.S. Geological Survey in Flagstaff, 

Arizona. Landsat scenes selected for computer 

enhancement are 1772-20565, taken September 

3, 1974; 1773-21020, taken September 4, 1974; 

and 2208-20425, taken August 18, 1975.

The black and white computer-enhanced products include horizontal, vertical, and diagonal 

first derivative images. Color computer-enhanced 

Landsat products include linearly "stretched" 

standard false color, sinusoidally "stretched" false 

color, and simulated natural color images. Because of geometric aberrations, image 2208- 

20425 could not be mosaicked by computer to the 

other two images. Thus, all computer-enhanced 

products are in two sections (see MF-878-J, sheet 

1). As a geologic mapping tool, Landsat imagery 

is probably most effective for reconnaissance 

studies, contributing remotely sensed information about geomorphology, structural features, 

and variations in spectral response of surficial 

materials, which can be used to plan and direct 

geologic mapping and geochemical sampling. 

However, in the Chandalar quadrangle, where 

reconnaissance geologic mapping and geochemical sampling were completed prior to the Landsat 

study, the Landsat interpretation augmented 

geological and geophysical observations by (1)

20
identifying the possible extensions of numerous 

mapped faults; (2) providing additional evidence 

for the presence and location of several possible 

faults that were not clearly evident on the ground 

or on aerial photographs; (3) identifying numerous lineaments that were undetected previously; 

(4) analyzing joint and fracture patterns on a 

quadrangle-wide basis; (5) identifying numerous 

circular features, some of which have diameters of 

over 150 km; (6) identifying arcuate features; and 

(7) detecting several iron oxide colored areas that 

have escaped recognition on the ground.

Several of these observed Landsat phenomena 

seem to be directly related to mineral resources. 

One of the more notable conjectured fault extensions passes through the two known porphyry 

copper deposits and closely coincides with the 

northern limit of the gold-bearing quartz-mica 

schist unit. A number of lineaments show a 

strong correlation with known mineralization 

and geochemical anomalies, suggesting a strong 

likelihood for significant mineralization in the 

Your Creek-Middle Fork area. Several of the observed concentric circular and arcuate features 

coincide with anticlines or synclines and with 

areas of copper or gold mineralization. Several 

iron oxided colored areas were identified on Landsat imagery and may warrant further field investigation.

Many of the methods used to apply Landsat imagery to mineral resource assessment in the 

Chandalar quadrangle are relatively new and 

their potential contribution toward better understanding of the areal geology remains to be fully 

explored. Several of the various computer enhancement techniques used to generate the Landsat imagery in this study have not yet been reported in the literature. Additionally, because a 

large number of lineaments and circular features 

observed on this imagery do not correspond to 

geologically known or geophysically inferred features and seem to indicate the workings of poorly 

understood, or perhaps even unknown, geologic or 

tectonic processes, their role in mineralization is 

rather vague at present.

REFERENCES

Alaska Division of Geological and Geophysical Surveys, 1973,

Annual Report: p. 27-30, p. 34-36. 

Albert, N. R. D., LeCompte, J. R., and Steele, W. C., 1978,

Interpretation of Landsat imagery of the Chandalar

quadrangle, Alaska: U.S. Geol. Survey Misc. Field 

Studies Map MF-878 J, 3 sheets, scale 1:250,000.

Armstrong, A. K., Mamet, B. L., Brosge, W. P., and Reiser, H. 

N., 1976, Carboniferous section and unconformity at 

Mount Doonerak, Brooks Range, northern Alaska: Am. 

Assoc. Petroleum Geologists Bull., v., 60, no. 6, p. 962- 

972.

Barnes, D. F., 1977, Bouguer gravity map of Alaska: U.S. 

Geol. Survey Geophys. Inves. Map GP-913, 1:2,500,000 

scale.

Berg, H. C., Eberlein, G. D., and MacKevett, E. M., Jr., 1964, 

Metallic mineral resources, in Mineral and water resources of Alaska: U.S. 88th Cong., 2d sess., Senate 

Comm. Interior and Insular Affairs, Comm. Print, p. 95- 

125.

Boyle, R. W., 1974, Elemental associations in mineral deposits 

and indicator elements of interest in geochemical prospecting (revised): Energy, Mines and Resources, Canada 

Geol. Survey Paper 74-45, 40 p.

Brobst, D. A., and Pratt, W. P., 1973, United States mineral 

resources: U.S. Geol. Survey Prof. Paper 820, 722 p.

Brosge, W. P., and Dutro, J. T. Jr., 1973, Paleozoic rocks of 

northern and central Alaska: Am. Assoc. Petroleum 

Geologists Mem. 19, p. 361-375.

Brosge, W. P., and Reiser, H. N., 1964, Geologic map and section of the Chandalar quadrangle Alaska: U.S. Geol. Survey Misc. Geol. Inves. Map 1-375, 1:250,000 scale.

 1972, Geochemical reconnaissance in the Wiseman and 

Chandalar districts and adjacent region, southern Brooks 

Range, Alaska: U.S. Geol. Survey Prof. Paper 709, 21 p.

Brosge, W. P., Reiser, H. N., and Yeend, Warren, 1973, Reconnaissance geologic map of the Beaver quandrangle, 

Alaska: U.S. Geol. Survey Misc. Field Studies Map MF525, 1:250,000.

Brosge, W. P., Reiser, H. N., Dutro, J. T., Jr., and Detterman, 

R. L., 1977, Generalized geologic map of the Philip Smith 

Mountains quadrangle, Alaska: U.S. Geol. Survey OpenFile Map OF-77-430, 1:200,000.

Cady, John W. 1978, Aeromagnetic map and interpretation of 

the Chandalar quadrangle, Alaska: U.S. Geol. Survey 

Misc. Field Studies Map MF-878-C, 2 sheets, scale 

1:250,000.

Chapman, R. M., Detterman, R. L., and Mangus, M. D., 1964, 

Geology of the Killik-Etivluk Rivers area, Alaska: U.S. 

Geol. Survey Prof. Paper 303-F, p 325-407.

Chipp, E. R., 1970, Geology and geochemistry of the Chandalar Area, Brooks Range, Alaska: Alaska Div. Mines and 

Geology, Geol. Rept. 42, 39 p.

Cobb, E. H., 1976, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Chandalar and Wiseman quadrangles, 

Alaska: U.S. Geol. Survey Open-File Rept. 76-340, 205 p.

Detra, D. E., Smith, S. C., Risoli, D. A., and Day, G. W., 1977, 

Spectrogaphic analyses of heavy mineral concentrate 

samples and chemical analyses of organic samples from 

the Chandalar quadrangle, Alaska: U.S. Geol. Survey 

Open-File Report 77-543, 151 p.

Detterman, R. L., Bowsher, A. L., and Dutro, J. T., Jr., 1958, 

Glaciation on the arctic slope of the Brooks Range, northern Alaska: Arctic, v. 11, no. 1, p. 43-61.

DeYoung, J. H., Jr., 1978, Mineral Resources Map of the 

Chandalar quadrangle, Alaska: U.S. Geol. Survey Misc. 

Field Studies Map, MF-878-B, one sheet, 1:250,000 scaje.

21
Dutro, J. T. Jr., Brosge, W. P., Lanphere, M. A., and Reiser, H. 

N., 1976, Geologic significance of Doonerak structural 

high, central Brooks Range, Alaska: Am. Assoc. Petroleum Geologists Bull., v. 60, no, 6, p 952-961.

Dutro, J. T., Jr., Brosge, W. P., and Reiser, H. N., 1977, Upper 

Devonian depositional history, central Brooks Range, 

Alaska: U.S. Geol. Survey Circ. 751-B, p. B16-B18.

Forbes, R. B., Garden, J. R., Turner, D. L., and Connelly, 

William, 1977, Tectonic implications of Alaskan blueschist terranes: Alaska Geol. Soc. Symposium Program 

and Abstracts, p. 21-22.

Foster, H. L., Albert, N. R. D., Barnes, D. F., Curtin, G. C., 

Griscom, Andrew, Singer, D. A., and Smith, J. G., 1976, 

The Alaskan Mineral Resource Assessment Program; 

Background information to accompany folio of geologic, 

and mineral resource map of the Tanacross quadrangle: 

U.S. Geol. Survey Circ. 734, 23 p.

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

and alterating-current spark emission spectrographic 

field methods for the semiquantitative analysis of geologic 

materials: U. S. Geol. Survey Circ. 591, 6 p.

Grahtz, Arthur, 1966, Strike-slip faults in Alaska: U.S. Geol. 

Survey open-file report, 82 p.

Hamilton, T. D., 1969, Glacial geology of the lower Alatna 

Valley, Brooks Range, Alaska, p. 181-223, in Schumm, S. 

A., and Bradley, W. C., eds., United States Contributions 

to Quaternary Research: Geol. Soc. Spec. Paper 123,305 p.

 1978, Surficial Geologic map, Chandalar quadrangle, 

Alaska: U.S. Geol. Survey Misc. Field Studies Map MF878A, 1 sheet, scale 1:250,000.

 1978, Surficial geologic map of the Philip Smith 

Mountains quadrangle, Alaska: U.S. Geol. Survey Misc. 

Field Inv. Map MF-879-A, scale 1:250,000.

1979, Quaternary stratigraphic sections with radiocarbon dates, Chandalar quadrangle, Alaska: U.S. Geol. 

Survey Open-File Report 79-751.

Hamilton, T. D., and Porter, S. C., 1975, Itkillik glaciation in 

the Brooks Range, northern Alaska: Quaternary Research, v. 5, no. 4, p. 471-497.

Hawley, C. C., 1976, Exploration and distribution of stratiform 

sulfide deposits in Alaska, in Recent and ancient sedimentary environments in Alaska, Symposium proceedings: 

Alaska Geol. Soc., p. T1-T23.

Heiner, L. E., and Wolff, E. N., 1968, Final report mineral 

resources of northern Alaska: MIRL Kept. 16, College 

Alaska, 306 p.

Hyndman,.D. W., 1972, Petrology of igneous and metamorphic 

rocks: N. Y., McGraw-Hill Book Co., 533 p.

Keroher, G. C., and others, 1966, Lexicon of geologic names of 

the United States for 1936-1960: U.S. Geol. Survey Bull. 

1200, 4341 p.

Lasky, S. G., 1947, The search for concealed deposits a 

reorientation of philosophy: Am. Inst. Mining Metall. Engineers Tech. Pub. No. 2146, 8 p.

Maddren, A. G., 1913, The Koyukuk-Chandalar Region, 

Alaska: U.S. Geol. Survey Bull. 532,119 p.

Marsh, S. P., Detra, D. E., and Smith, S. C., 1978, Geochemical 

and generalized geologic map showing distribution and 

abundance of copper, molybdenum, and lead in stream 

sediments in the Chandalar quadrangle, Alaska: U.S. 

Geol. Survey Misc. Field Studies Map MF-878-D, 1 sheet, 

scale 1:250,000.

 1978, Geochemical and generalized geologic map showing distribution and abundance of zinc in stream sediments in the Chandalar quadrangle, Alaska: U.S. Geol. 

Survey Misc. Field Studies Map MF-878-E, 1 sheet, scale 

1:250,000

 1978, Geochemical and generalized geologic map showing distribution and abundance of barium, arsenic, boron, 

and vanadium in stream sediments in the Chandalar 

quadrangle, Alaska: U.S. Geol. Survey Misc. Field 

Studies Map MF-878-G, 1 sheet, scale 1:250,000

 1979, Geochemical and generalized geologic map showing distribution and abundance of nickel, cobalt, lanthanum, and yttrium in stream sediments in the Chandalar 

quadrangle, Alaska: U.S. Geol. Survey Misc. Field 

Studies Map MF-878-F, 1 sheet, scale 1:250,000 (in 

press).

1979, Geochemical and generalized geologic map showing distribution and abundance of antimony and niobium 

in stream sediments in the Chandalar quadrangle, 

Alaska: U.S. Geol. Survey Misc. Field Studies Map MF878-H, 1 sheet, scale 1:250,000 (in press).

Marsh, S. P., and Wiltse, M. A., 1979, Composite geochemical 

map showing major alteration zones, and detailed 

geologic maps of selected mineral prospects, Chandalar 

quadrangle, Alaska: U.S. Geol. Survey Misc. Field 

Studies Map MF-878-1,1 sheet, scale 1:250,000 (in press).

Mertie, J. B., Jr., 1925, Geology and gold placers of the Chandalar district, Alaska: U.S. Geol. Survey Bull. 773-E, p. 

215-263.

Mulligan, J. J., 1974, Mineral resources of the trans-Alaska 

pipeline corridor: U.S. Bur. Mines Inf. Circ. 8626, 24 p.

O'Leary, R. M., McDanal, S. K., McDougal, C. M., Day, G. W., 

and Marsh, S. P., 1976, Chemical analyses and statistical 

data for stream sediment samples from the Chandalar 

quadrangle, Alaska: U.S. Geol. Survey Open-File Report 

OF-76-492,115 p., 1 map.

Oliver W. A., Merriam, C. W., and Churkin, Michael, Jr., 

1975, Ordovician, Silurian and Devonian corals of Alaska: 

U.S. Geol. Survey Prof. Paper 823-B, p. 13-44.

Patton, W. W., Jr., 1973, Reconnaissance geology of the northern Yukon-Koyukuk Province, Alaska: U.S. Geol. Survey 

Prof. Paper 774-A, 17 p.

Patton W. W., Jr., and Miller, T. P., 1973, Bedrock geologic 

map of Settles and southern part of Wiseman quadrangles, Alaska: U.S. Geol. Survey Misc. Field Studies Map 

MF-492,1:250,000.

Patton, W. W., Jr., Tailleur, I. L., Brosge, W. P., and Lanphere, 

M. A., 1977, Preliminary report on the ophiolites of northern and western Alaska, in North American Ophiolites: 

Oregon State Dept. Geol. and Mineral Industries Bull. 95.

Payne, T. G., 1955, Mesozoic and Cenozoic tectonic elements of 

Alaska: U.S. Geol. Survey Misc. Geol. Inv. Map 1-84, 

scale 1:5,000,000

Reed, I. M., 1927, Report on some of the quartz prospects of the 

Chandalar district: Alaska Terr. Dept. Mines, Misc. Inv. 

31-2, 4 p.

 1929, Report on mining conditions in the Chandalar 

district: Alaska Terr. Dept. Mines, Misc. Inv. 31-3, 5 p.

 1930, Report on the Little Squaw area of the Chandalar 

Mining district: Alaska Terr. Dept. Mines, Misc. Inv. 

31-4,17 p.

 1938, Upper Koyukuk region, Alaska: Alaska Dept.

22
Mines unpublished report, 169 p. 

Sable, E. G., 1977, Geology of the western Romanzof

Mountains, Brooks Range, Alaska: U.S. Geol. Survey

Prof. Paper 897, 84 p. 

Saunders, R. H., 1963, Report on exploration in the Chandalar

district, 1962, Alaska Div. Mines and Geology, Misc.

Inv., 4 p. 

Schrader, F. C., 1900, Preliminary report on a reconnaissance

along the Chandalar and Koyukuk Rivers, Alaska, in

1899: U.S. Geol. Survey Twenty-first Ann. Rept., pt. 2, p

441-486. 

Schrader, F. C., 1904, A reconnaissance in northern Alaska:

U.S. Geol. Survey Prof. Paper 20,139 p. 

Stanford, J. V., 1934, Report on Little Squaw, Bonanza, and

Mikado groups of claims, Chandalar, Alaska: Alaska

Terr. Dept. Mines, Misc. Inv. 31-5,10 p. 

Thompson, G. L., 1925, Report on the property of the Chandalar Gold Company: Alaska Terr. Dept. Mines, Misc. Inv.

31-1, 36 p. 

Turner, F. J., and Verhoogen, John, 1960, Igneous and

Metamorphic Petrology: N.Y., McGraw-Hill Book Co.

Inc., 694 p.

U.S. Bureau of Mines and U.S. Geological Survey, 1976, Principles of the mineral resource classification system of the 

U.S. Bureau of Mines and U.S. Geological Survey: U.S. 

Geol. Survey Bull. 1450-A, 5 p.

U.S. Geological Survey, 1973, Aeromagnetic Survey, western 

half of Chandalar quadrangle, northeast Alaska: U.S. 

Geol. Survey open-file map, 1 sheet, scale 1:250,000

 1974, Aeromagnetic map of eastern half of the 

Chandalar quadrangle, northeastern Alaska: U.S. Geol. 

Survey open-file map, 1 sheet, scale 1:250,000 

-1975, Mated metamorphic beds (sic) in southern Brooks

Range, in Geological Survey research 1975: U.S. Geol.

Survey Prof. Paper 975, p. 66. 

Wahrhaftig, Clyde, 1965, Physiographic divisions of Alaska:

U.S. Geol. Survey Prof. Paper 482, 52 p. 

Ward, F. M., Lakin, H. W., Canney, F. C., and Van Sickle, G.

H., 1969, Atomic absorption methods of analysis useful in

geochemical exploration: U.S. Geol. Survey Bull. 1289, 45

PWilliams, J. R., 1962, Geologic reconnaissance of the Yukon 

Flats District, Alaska: U.S. Geol. Survey Bull. 1111-H, p. 

289-331.

23