C-14

L/B

C20

N-4

L/B

M-3

M/B

M4

N-2

M/B

I-2

L/B

C-13

L/B

C19

C-12

L/B

C18

C-11

L/B

C-9

M/C

C17

C16

C15 C14 C13

C12

C-10

L/B

C11

I-1

L/B

N-3

L/B

M-1

H/D M3

M2

M1

M-2

M/B

C-8

M/C

C10

C9

C8

C7

N-1

H/C

N1

N2

N3 N4

N5

C-7

L/B

C-6

L/B

C-5

L/B

C-4

M/C

C6

C-3

M/C

C5

C-1

H/D

C4A

C4B

C3

C-2

M/C

C2

C1

G-19

L/B

G1

G-14

L/B

P-3

L/B

P-1

L/B G-11

L/B

G-11

L/B

P-2

L/B

G-11

L/B

G-13

M/B

G-9

M/B

G8

G9 G10

G11

G-11

L/B

G-12

M/C

G6

G7

G-16

M/B

G4

G5

G-17

L/B G3

G-18

L/B

G2

G-8

M/C

G-10

M/B

PL-9

L/C

G-3

H/B

PL-8

M/C

G-10

M/B

G-11

L/B

G-7

G-2 M/C

H/D

G12

G13

G14 G15

G16

G17

G18

G19 G20

G21

G-6 G22

M/C

G-10

M/B

G-10

M/B

G24

G25

G23

G-5

M/C

PL-5

M/C PL-6

H/C

PL-7

M/C

PL-4

M/C G-4

M/C

G-4

M/C

PL-3

M/C

G-4

M/C PL-2

M/C

G61

G60

G59

G57

G58

G-15

L/B

PL-1

M/C

G-1

H/D

G-1

H/D G56

G55

G54

G53

G52 G51

G50

G49

G48

G47

G46

G45 G44

G43

G42 G41

G40

G39

G38

G37

G36

G35

G34

G33

G32

G31

G30 G29

G28

G27

G26

Km

Km

Km

Km

Qs

Th

Jdt

Jdt

Jdt

Jdt

Qs

Th Ji

Th

Th

Ji

Ji

Jum

Jmp Jmp

Jmp

Jmp

Th

Th

TKm Jum

TKm

Qs

Qs

cm

cm

cm

g

g Jhhc

Jhhc

Jmp

cm

Jm

Kvs

Kvs

Qs

Qs

Kvv

cm

g

Kvs Th

Kvs

Th

Qs

Qs

Kvs

Kvs

Kvv

Kvv

g

g

Tos

Tos

Tos

Tov

Tov

Km

Jdt

Qs

Jdt

Ji

Ji

Jmp

Th

cm

cm

Jum

g

Qs

Qs

Th

Jm

Jm

Jum

g Qs

Qs

cm

Kvs

Kvs

Qs

g

g

Kvs

g

Kvv

Kvs

Kvs

Jm

Jdt Ji

Ji

Jmp

cm

cm

Jm

cm

Qs

Th cm

Th

Kvs

Kvs

Qs

Kvs

Kvs

Kvs

Th

g

Qs

Qs

Jdt

Jmp

Kvs

Th

Qs

Qs

Th

Th

Kvv

g

Qs

Kvv

Th

Kvv

Kvv

Jdt

Jmp

Jmp

Qs

cm

Th

Jmp

cm

Jhhc

Jum

Kvs

g

Qs

Th

Qs

Jmp

Jum

cm

Jhhc

Th

Th

Kvv

Jhhc

g

Kvs

Kvs

Kvs

Kvs

Kvs

Kvv

Kvv

Jmp

Jmp

Qs

Qs

QTw

QTw

QTw

QTw

QTw QTw

QTw

Jhhc

Jhhc

dn

Jhhc

Jc

Jc

Jc

Th

Ks

Phs

Jdc

g

Ks Phs KsJdc

Jc

Phs

Phs

Jdc

QTw

Qs

Jc

Jc

Th

dn

g

Jmp

Jmp

Jum

Jm

Jm

Jm

QTw

Jc

Jhhc

dn

Phs

QTw

Jdt

dn

dn

Jhhc

Th

Th

Th

Jum Jm

cm

cm Kvs

Kvs

Jum

Jhhc

Jhhc

Th

Qs

Qs

Jc

Jc

Jc

Jhhc

Jhhc

Jhhc

Jhhc

Ks

dn

dn

dn

Th

Jdc

Jdc

Qs

Qs

Jhhc

Jhhc

Jhhc

Qs

g

Jum

Jum

Th

Jhhc

g

Jum

Qs

g

Kvv

Qs Qs

Qs

Qs

g

g

g

Th

Kvv

Km

Km

Km

Km

Qs

Th

Jdt

Jdt

Jdt

Jdt

Qs

Th Ji

Th

Th

Ji

Ji

Jum

Jmp Jmp

Jmp

Jmp

Th

Th

Jum

TKm

TKm

Qs

Qs

cm

cm

cm

g

g Jhhc

Jhhc

Jmp

cm

Jm

Kvs

Kvs

Qs

Qs

Kvv

cm

g

Kvs Th

Kvs

Th

Qs

Qs

Kvs

Kvs

Kvv

Kvv

g

g

Tos

Tos

Tos

Tov

Tov

Km

Jdt

Qs

Jdt

Ji

Ji

Jmp

Th

cm

cm

Jum

g

Qs

Qs

Th

Jm

Jm

Jum

g Qs

Qs

cm

Kvs

Kvs

Qs

g

g

Kvs

g

Kvv

Kvs

Kvs

Jm

Jdt Ji

Ji

Jmp

cm

cm

Jm

cm

Qs

Th cm

Th

Kvs

Kvs

Qs

Kvs

Kvs

Kvs

Th

g

Qs

Qs

Jdt

Jmp

Kvs

Th

Qs

Qs

Th

Th

Kvv

g

Qs

Kvv

Th

Kvv

Kvv

Jdt

Jmp

Jmp

Qs

cm

Th

Jmp

cm

Jhhc

Jum

Kvs

g

Qs

Th

Qs

Jmp

Jum

cm

Jhhc

Th

Th

Kvv

Jhhc

g

Kvs

Kvs

Kvs

Kvs

Kvs

Kvv

Kvv

Jmp

Jmp

Qs

Qs

QTw

QTw

QTw

QTw

QTw QTw

QTw

Jhhc

Jhhc

dn

Jhhc

Jc

Jc

Jc

Th

Ks

Phs

Jdc

g

Ks Phs KsJdc

Jc

Phs

Phs

Jdc

QTw

Qs

Jc

Jc

Th

dn

g

Jmp

Jmp

Jum

Jm

Jm

Jm

QTw

Jc

Jhhc

dn

Phs

QTw

Jdt

dn

dn

Jhhc

Th

Th

Th

Jum Jm

cm

cm Kvs

Kvs

Jum

Jhhc

Jhhc

Th

Qs

Qs

Jc

Jc

Jc

Jhhc

Jhhc

Jhhc

Jhhc

Ks

dn

dn

dn

Th

Jdc

Jdc

Qs

Qs

Jhhc

Jhhc

Jhhc

Qs

g

Jum

Jum

Th

Jhhc

g

Jum

Qs

g

Kvv

Qs Qs

Qs

Qs

g

g

g

Th

Kvv

Jm Jm

Jm

Jm Jm

Jm

Kvv

Kvv

CONTACT

FAULT

TAZLINA

FAULT

ST ANNE FAULT

ST ANNE

BO

FAULT

RDER

RANGES

FAULT

KLUTINA

FAULT

ICEBERG

FAULT

TAZLINA

FAULT

BORDER

RANGES

FAULT

CHITINA FAULT

TEBAY FAULT

CANYON

CREEK FAULT

BORDER

RANGES

FAULT

BORDER

RANGES

FAULT

SECOND LAKE FAULT

TAZLINA

FAULT

TARAL FAULT

BORDER

RANGES

FAULT

BORDER

FAULT

RANGES

CONTACT

FAULT

TAZLINA

FAULT

ST ANNE

FAULT

ST ANNE

BOR

FAULT

DER

RANGES

FAULT

KLUTINA

FAULT

ICEBERG

FAULT

TAZLINA

FAULT

BORDER

RANGES

FAULT

CHITINA FAULT

TEBAY FAULT

CANYON

CREEK FAULT

BORDER

RANGES

FAULT

BORDER

RANGES

FAULT

SECOND LAKE FAULT

TAZLINA

FAULT

TARAL FAULT

BORDER

RANGES

FAULT

BORDER

FAULT

RANGES

U.S. DEPARTMENT OF THE INTERIOR

U.S. GEOLOGICAL SURVEY

GEOLOGIC INVESTIGATIONS SERIES

I–2652

Pamphlet accompanies map

MAPS SHOWING AREAS OF POTENTIAL FOR METALLIC MINERAL RESOURCES IN THE VALDEZ 1° x 3° QUADRANGLE, ALASKA

By

G.R. Winkler, R.J. Goldfarb, W.J. Pickthorn, and D.L. Campbell

1999

MAP A. GEOLOGY AND AREAS OF POTENTIAL FOR PRECIOUS- AND BASE-METAL VEIN DEPOSITS AND FOR PRECIOUS-METAL PLACERS

MAP B. GEOLOGY AND AREAS OF POTENTIAL FOR BASE AND FERROUS METALS IN VOLCANIC- AND INTRUSIVE-RELATED DEPOSITS

Base from U.S. Geological Survey, 1960.

100,000-foot grid based on Alaska Coordinate System, zone 3.

10,000-meter Universal Transverse Mercator grid ticks, zone 6.

Universal Transverse Mercator Projection. 1927 North American Datum.

Geology modified from Winkler and others (1995)

Geology digitized by Nora Shew

Editing and digital cartography by Alessandro J. Donatich

Manuscript approved for publication July 9, 1998

Any use of trade names in this publication is for

descriptive purposes only and does not imply 

endorsement by the U.S. Geological Survey

For sale by U.S. Geological Survey Information Services

Box 25286, Federal Center, Denver, CO 80225

This map is also available as a PDF at http://greenwood.cr.usgs.gov

5 5 0 10 15 20 25 30 KILOMETERS

SCALE 1:250 000

5 0 5 15 20 MILES 10

CONTOUR INTERVAL 200 FEET

NATIONAL GEODETIC VERTICAL DATUM OF 1929

1960 MAGNETIC DECLINATION AT SOUTH EDGE OF SHEET VARIES FROM 27°00' TO 28°00' EAST

Printed on recycled paper

DESCRIPTION OF MAP UNITS FOR MAPS A AND B

ALL TERRANES

Surficial deposits

Surficial deposits, undivided (Quaternary)

Plutonic rocks

Hypabyssal intrusive rocks (Eocene)—Altered granite, granodiorite, or tonalite

WRANGELLIA TERRANE

Sedimentary and volcanic rocks

Wrangell Lava (Holocene to Miocene)

Marine sedimentary rocks (Early Cretaceous)—As mapped, consists of Berg Creek 

Formation and unnamed marine sedimentary rocks

Marine clastic and carbonate rocks, undivided (Late or Middle Jurassic to Late 

Triassic)—As mapped, consists of Kotsina Conglomerate (Middle or Late Jurassic), lower 

part of McCarthy Formation (Late Triassic), and Chitistone and Nizina Limestones (Late 

Triassic)

Nikolai Greenstone (Late and (or) Middle Triassic)

Skolai Group (Early Permian and Pennsylvanian)

Plutonic rocks

Chitina Valley batholith (Late Jurassic)

Metamorphic rocks

Haley Creek metamorphic assemblage (Late Jurassic and Pennsylvanian or older?)—As 

mapped, consists of Uranatina River metaplutonic unit (Jurassic and Pennsylvanian) and 

Strelna Metamorphics of Plafker and others (1989a) (Early Pennsylvanian and older?)

PENINSULAR TERRANE

Sedimentary and volcanic rocks

Matanuska Formation (Late and Early Cretaceous)

Talkeetna Formation (Early Jurassic and Late Triassic?)

Plutonic rocks

Intrusive rocks (Late Jurassic)—As mapped, consists of tonalite, granodiorite, and graphic 

granite

Layered mafic plutonic rocks (Middle Jurassic and older?)—As mapped, consists of the 

Nelchina River Gabbronorite (Middle Jurassic and older?), layered gabbro of the Tonsina 

ultramafic-mafic sequence, and layered quartz-bearing gabbro of Klanelneechena Creek

Ultramafic rocks (Middle Jurassic and older)—As mapped, consists of harzburgite, dunite, 

and websterite of the Tonsina ultramafic-mafic sequence

CHUGACH TERRANE

Sedimentary and volcanic rocks

Valdez Group (Late Cretaceous)

Sedimentary rocks

Mafic volcanic rocks

McHugh Complex (Mesozoic)

Metamorphic rocks

Melange (Tertiary or Cretaceous)

Greenschist and transitional blueschist facies metamorphic rocks (Jurassic or older)—As 

mapped, consists of schist of Liberty Creek and schist of Iceberg Lake

PRINCE WILLIAM TERRANE

Sedimentary and volcanic rocks

Orca Group (Eocene and Paleocene)

Flyschoid sedimentary rocks

Tholeiitic volcanic rocks

Glaciers and superglacial moraine

Contact—Approximately located. Dotted where concealed; queried where assumed

High-angle fault—Approximately located. Dotted where concealed; queried where assumed

Thrust fault—Approximately located. Sawteeth on upper plate. Dotted where concealed; 

queried where assumed

Qs

Th

QTw

Ks

Jc

Km

Ji

TKm

Jm

Jmp

Jum

Kvv

Kvs

Tov

g

Tos

cm

Jdc

Jdt

dn

Phs

Jhhc

Qs

Th

QTw

Ks

Jc

Km

Ji

TKm

Jm

Jmp Jum

Kvv Kvs

Tov Tos

cm

Jdc

Jdt

dn

Phs

Jhhc

Eocene

Holocene to Miocene

Early Cretaceous

Late or Middle Jurassic

to Late Triassic

Late and (or) Middle Triassic

Late Jurassic

Late and Early Cretaceous

Early Permian and

Pennsylvanian

Late Jurassic and

Pennsylvanian and older(?)

Early Jurassic and

Late Triassic(?)

Late Jurassic

Late Cretaceous

Eocene and Paleocene

Middle Jurassic and

older(?)

QUATERNARY

TERTIARY

QUATERNARY AND TERTIARY

CRETACEOUS

JURASSIC AND TRIASSIC

TRIASSIC

JURASSIC

CRETACEOUS

CRETACEOUS

TERTIARY OR CRETACEOUS

TERTIARY

JURASSIC OR OLDER

JURASSIC AND TRIASSIC(?)

JURASSIC

JURASSIC AND OLDER(?)

PERMIAN AND PENNSYLVANIAN

JURASSIC AND PENNSYLVANIAN

AND OLDER(?)

MESOZOIC

CORRELATION OF MAP UNITS FOR MAPS A AND B

ALL TERRANES

Surficial deposits

WRANGELLIA TERRANE

Sedimentary and volcanic rocks

PENINSULAR TERRANE

Sedimentary and volcanic rocks

CHUGACH TERRANE

Sedimentary and volcanic rocks

PRINCE WILLIAM TERRANE

Sedimentary and volcanic rocks

Plutonic rocks

Plutonic rocks

Plutonic rocks

Metamorphic rocks

Metamorphic rocks

HIGH

POTENTIAL

MODERATE

POTENTIAL

LOW

POTENTIAL

LOW

POTENTIAL

LOW

POTENTIAL

NO

POTENTIAL

UNKNOWN

POTENTIAL

MODERATE

POTENTIAL

MODERATE

POTENTIAL

HIGH

POTENTIAL

HIGH

POTENTIAL

INCREASING LEVEL OF CERTAINTY

INCREASING LEVEL OF RESOURCE POTENTIAL

U/A H/B

M/B

L/B

H/C

M/C

L/C

H/D

M/D

L/D

N/D

AB C D

RELATION BETWEEN LEVELS OF RESOURCE POTENTIAL AND CERTAINTY1

1Levels of certainty:

A Available information is not adequate for determination of the level of mineral resource potential.

B Available information only suggests the level of mineral resource potential.

C Available information gives a good indication of the level of mineral resource potential.

D Available information clearly defines the level of mineral resource potential.

EXPLANATION OF MINERAL RESOURCE POTENTIAL FOR MAP A

Tracts favorable for undiscovered occurrences of mineral deposits of the specified 

types—Number refers to tracts characterized in tables 2–5. G, low-sulfide gold-quartz 

veins (see table 2); P, polymetallic veins (see table 5)

Reach of drainage favorable for occurrences of placer deposits—Number refers to stream 

listed in table 2

Levels of resource potential and certainty—See “Relation between levels of resource 

potential and certainty” diagram on this sheet

Location of known occurrence of low-sulfide gold-quartz vein deposit—Number refers to 

site listed in table 2

EXPLANATION OF MINERAL RESOURCE POTENTIAL FOR MAP B

Tracts favorable for undiscovered occurrences of mineral deposits of the specified 

types—Number refers to tracts characterized in tables 2–5. C, massive sulfide deposits 

(see table 3); M, layered and podiform chromite deposits (see table 4); N, nickel-copper 

sulfide deposits (see table 4); I, porphyry copper-molybdenum deposits (see table 5)

Levels of resource potential and certainty—See “Relation between levels of resource 

potential and certainty” diagram on this sheet

Location of known occurrence of massive sulfide deposit—Number refers to site listed in 

table 3

Location of known occurrence of layered and podiform chromite deposit—Number refers 

to site listed in table 4

Location of known occurrence of nickel-copper sulfide deposit—Number refers to site 

listed in table 4

G-1

H/B

PL-1

G38

C-9

H/B

C16

M3

N1
U.S. DEPARTMENT OF THE INTERIOR

U.S. GEOLOGICAL SURVEY

MAPS SHOWING AREAS OF POTENTIAL FOR METALLIC MINERAL

RESOURCES IN THE VALDEZ 1° x 3° QUADRANGLE, ALASKA

By

G.R. Winkler, R.J. Goldfarb, W.J. Pickthorn, and D.L. Campbell

1999

Pamphlet to accompany

GEOLOGIC INVESTIGATIONS SERIES

I–2652
i

CONTENTS

Page

Summary ....................................................................................................................................... 1

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

Area description ................................................................................................................. 2

Background studies ........................................................................................................................ 2

Geologic mapping ............................................................................................................... 2

Geochemical studies .......................................................................................................... 2 .

Geophysical studies ............................................................................................................ 6

Landsat imagery ................................................................................................................. 6

Mines, prospects, and mineral occurrences .......................................................................... 6

Geologic setting for mineral resources ....................................................................................... 7 .....

Wrangellia terrane .............................................................................................................. 7

Peninsular terrane .............................................................................................................. 7

Chugach terrane .............................................................................................................. 10

Prince William terrane ....................................................................................................... 10

Resource assessment methods 10 .....................................................................................................

Known mineral deposit types .................................................................................................. 11 ......

Vein deposits .................................................................................................................... 11

Low-sulfide gold-quartz veins (precious-metal veins) ................................................ 11

Massive sulfide deposits .................................................................................................... 14

Volcanogenic massive sulfide deposits ................................................................... 14

Kennecott-type deposits ....................................................................................... 16

Magmatic deposits ............................................................................................................ 17

Layered and podiform chromite deposits ................................................................ 17

Nickel-copper sulfide deposits ................................................................................ 18

Placer deposits ................................................................................................................. 19

Precious-metal placers ........................................................................................... 19

Postulated mineral deposit types ............................................................................................. 19 ......

Vein deposits .................................................................................................................... 19

Polymetallic veins (base- and precious-metal veins) ................................................. 19

Stockwork deposits .......................................................................................................... 20

Porphyry copper-molybdenum stockworks and veins ............................................. 20

References cited ........................................................................................................................... 20
ii

FIGURES

1. Map showing major physiographic and cultural features and lithotectonic terranes of the

Valdez 1° x 3° quadrangle, Alaska ........................................................................................... 3

2. Map showing generalized geology of the Valdez 1° x 3° quadrangle, Alaska ................................ 4

3. Map showing metallic mines, prospects, and occurrences in the Valdez 1° x 3° quadrangle,

Alaska ................................................................................................................................... 8

TABLES

1. Classification of mineral deposit types for the Valdez 1° x 3° quadrangle, Alaska ........................ 11

2. Characteristics of tracts favorable for low-sulfide gold-quartz veins and drainages

favorable for precious-metal placers in the Valdez 1° x 3° quadrangle, Alaska .......................... 26

3. Characteristics of tracts favorable for massive sulfide deposits in the Valdez 1° x 3°

quadrangle, Alaska ............................................................................................................... 32

4. Characteristics of tracts favorable for magmatic deposits in the Valdez 1° x 3°

quadrangle, Alaska ............................................................................................................... 36

5. Characteristics of tracts favorable for polymetallic vein deposits and permissive for

porphyry copper-molybdenum deposits in the Valdez 1° x 3° quadrangle, Alaska .................... 38
1

SUMMARY

Interpretation of geological, geochemical,

geophysical, and mineral-deposit data has identified

areas of metallic mineral-resource potential in the

Valdez quadrangle, south-central Alaska, where

undiscovered resources of precious, base, or ferrous

metals are likely to occur. Nineteen areas, encompassing approximately 75 percent of the quadrangle,

have potential for gold (±silver) in low-sulfide goldquartz veins. Two areas underlain by rocks of the

Valdez Group of the Chugach terrane (tracts G-1 and

G-2) have mines with recorded production and have

high potential for hosting additional gold resources;

another area without mines (tract G-3) is presumed

to have high potential also. Sixteen other areas

underlain by the Valdez Group (tracts G-4 through

G-19) are considered to have moderate or low potential. Three addtional areas in the Chugach terrane

(tracts P-1 through P-3) have low potential for

polymetallic veins, although no specific occurrences

are known. Seven streams along the southern or

eastern edges of the quadrangle have moderate

potential for occurrences of placer gold (tracts PL-1

through PL-5 and PL-7 and PL-8), one stream (tract

PL-6) has a high potential, and one stream (tract PL9) has a low potential.

Several areas underlain by rocks of the Valdez

Group also have potential for volcanogenic massive

sulfide deposits. South of the town of Valdez, an

area of high potential for copper resources (tract C1) includes several mines near the head of Solomon

Gulch that have recorded production and indicated

reserves from Besshi-type deposits. Six other areas

with moderate or low potential for the occurrence

of Besshi- or Cyprus-type volcanogenic massive sulfide deposits have been identified within the Chugach

terrane (tracts C-2 through C-7). North of the Border Ranges fault system, copper enrichments are

known in several places in metavolcanic rocks of the

southern margin of the Wrangellia terrane (tracts C-8

and C-10), the type Wrangellia terrane (tracts C-9,

C-11, and C-12), and the Peninsular terrane (tracts

C-13 and C-14). Tracts C-8 and C-9 have moderate

potential for volcanogenic massive sulfide deposits;

tracts C-10 through C-14 have low potential. Generally, these copper occurrences are small veins,

pods, disseminations, and fracture coatings, either

solitary or in closely spaced multiple occurrences. A

few veins or pods are rich, but most contain only

sparse or irregularly distributed metallic minerals. Although these copper deposits are likely to have

formed syngenetically during Late Paleozoic or Early

Jurassic arc-related submarine volcanism (deposits

hosted by the Skolai Group or Talkeetna Formation,

respectively), or during Late Triassic subaerial mafic

volcanism (deposits hosted by the Nikolai Greenstone), a few deposits exhibit some hydrothermal

remobilization. This may be related to Late Jurassic

plutonism that produced numerous mesozonal intrusions known collectively as the Chitina Valley

batholith. Along the eastern edge of the quadrangle

near Copper Creek (tract C-9), a few small discordant lodes in the Upper Triassic Chitistone Limestone

may be of the same type as the stratabound

Kennecott-type deposits in the McCarthy quadrangle

to the east.

Areas of potential for chromium and nickel

resources are associated with mafic and ultramafic

rocks in the Peninsular and southern margin of the

Wrangellia terranes. In the Bernard Mountain area

east of Tonsina, outcrops of layered dunite and tectonized harzburgite contain chromite-rich layers as

much as several meters thick. Inferred total resources in this area of high potential (tract M-1) exceed 440,000 tons of ore at 5–11 percent Cr2 O3,

and constitute a significant resource of chromium.

Several nearby areas of moderate potential for

chromium and nickel resources in tectonized ultramafic bodies also have been identified (tract M-2),

and a low potential exists for magmatic sulfide deposits enriched in nickel and copper in overlying layered gabbroic rocks (tract N-3). East of Tonsina in

the Spirit Mountain area, a tract (N-1) has high potential for nickel and associated copper and platinum

resources. At the Spirit Mountain prospect, massive

and disseminated sulfide minerals occur in small mafic

and ultramafic sills; the occurrences contain as much

as 7.6 percent Ni. Inferred resources total about

6,500 tons averaging 0.7 percent Ni. In the northwestern part of the Valdez quadrangle, a moderate

potential for chromium resources exists in an area

south of the Border Ranges fault between Nelchina

and Tazlina Glaciers (tract M-3). Areas of moderate

and low potential for nickel resources, respectively,

occur in nearby layered mafic intrusions along

Klanelneechena Creek (tract N-2) and north of the

Border Ranges fault (tract N-4).

INTRODUCTION

This report is one of a series of maps and reports produced as part of the U.S. Geological Survey’s Alaska Mineral Resource Assessment Program

(AMRAP) investigations of the geologic setting for

metallic mineral resources in the Valdez 1° x 3 °

quadrangle, south-central Alaska. Other AMRAP

products for the quadrangle summarize bedrock and

surficial geology, geochronology, aeromagnetic and

satellite imagery, and known mineral-resource occurrences, and provide the data from reconnaissance

geochemical studies; references are provided in

Winkler and others (1992), which also includes brief

synopses of each product and related background investigations. The current report is principally based

on information presented in earlier AMRAP reports,

but also draws on addtional older sources of information on mineral-resource occurrences in the quadrangle. Many older sources are incomplete and do

not provide sufficient information for accurate determination of mineral deposit types; however, these

sources do provide valuable historic information on

early exploration and production.

The purpose of this report is to delineate the

boundaries of tracts that are considered to be favorable for the occurrence of undiscovered metallic

mineral resources in the Valdez quadrangle, based on

interpretation of available geological, geochemical,
2

and geophysical data. The maps and accompanying

text and tables synthesize information on known

mines, prospects, and occurrences, mapped geologic

units and structures, and geochemical and geophysical anomalies that may indicate metal concentrations.

Two maps outline tracts with characteristics that favor the occurrences of specific types of mineral deposits: map A shows resource tracts for preciousand base-metal vein deposits and for gold placers;

map B shows resource tracts for base and ferrous

metals in volcanic- and intrusive-related deposits. In

characterizing mineral deposit types, we generally

follow the descriptive classifications of Cox and

Singer (1986) or Bliss (1992). In the case of the

Kennecott-type copper deposits, we follow the

characteristics described by MacKevett and others

(1997). This report should be used in conjunction

with the report by Goldfarb and others (1995),

which provides a concise summary of known mineral

resources in the quadrangle and outlines areas of

mineral-resource favorability based on the presence

of geochemcally anomalous samples.

AREA DESCRIPTION

The Valdez quadrangle (fig. 1) includes an area

of approximately 18,000 km2 of south-central Alaska

bounded by the 61° and 62° North parallels and by

the 144° and 147° West meridans. Much of the

quadrangle is mountainous: the central and southern

parts are dominated by the rugged and glaciated

Chugach Mountains and the northeastern part by the

flanks of the lofty Wrangell Mountains, including

much of the broad volcanic shield of Mt. Wrangell.

The lowlands of the Copper River Basin occupy the

northern part of the quadrangle. Transecting the

lowlands and the Chugach Mountains from north to

south is the Copper River, which is joined by a major

tributary, the Chitina River, near the east-central

edge of the quadrangle. Total relief in the quadrangle is 4,252 m from the summit of Mt. Wrangell in

the northeast corner to sea level in Valdez Arm and

Port Valdez in the southwest corner. The southwest

corner is included within the Chugach National Forest

and the area east of the Copper River is included

within the Wrangell-St. Elias National Park and

Preserve.

Road access to the Valdez quadrangle is limited. The Richardson Highway passes through the

center of of the quadrangle from Copper Center to

Valdez, and the Glenn Highway passes through the

far northwestern corner. Valdez is the largest town

in the quadrangle, with a 1990 population of 4,635.

Copper Center is the only other town in the quadrangle; its 1990 population was 449. Parts of the

east side of the quadrangle are accessible from the

Edgerton Highway, which heads east from the

Richardson Highway to the settlements of Kenney

Lake, Lower Tonsina, and Chitina, and by the Chitina

to McCarthy gravel road, which crosses the Copper

River by a bridge at Chitina and extends eastward

into the Wrangell-St. Elias National Park and Preserve. Port Valdez, the southern terminus of the

trans-Alaska oil pipeline, is accessible by ship from

Prince William Sound. The Valdez airport is served

by commercial air service and there are numerous

other air fields and bush airstrips in the quadrangle,

most of them minimally improved and served only by

charter operations. Widely scattered lakes, mostly in

the Copper River Basin, may be reached by aircraft

on floats. Due to the rugged, steep, glaciated terrain

in much of the remainder of the quadrangle, it generally is accessible only on foot or by helicopter.

BACKGROUND STUDIES

GEOLOGIC MAPPING

The earliest published geologic observations

covering parts of the Valdez quadrangle are from the

late 1800’s in reports from U.S. Army expeditions to

explore the valleys of the Copper and Chitina Rivers.

During the early 1900’s, as exploration for mineral

resources began to spread from Prince William

Sound into the interior of Alaska, many reports included geologic observations or maps of local areas

within the quadrangle. However, it was not until

1981, as part of AMRAP, that the first regional geologic map of the entire Valdez quadrangle (scale

1:250,000) was completed (Winkler and others,

1981b). Subsequently, as part of the USGS TransAlaska Crustal Transect (TACT) project, a more detailed geologic map of a north-south tier of quadrangles (scale 1:125,000) was completed in the

vicinity of part of the Richardson Highway (Plafker

and others, 1989a). Companion TACT reports provided tectonic (Plafker and others, 1989b) and structural (Nokleberg and others, 1989) syntheses, including detailed descriptions of the four lithotectonic terranes that make up the Valdez quadrangle—the

Wrangellia, Peninsular, Chugach, and Prince William

terranes (figs. 1, 2). Regional geologic mapping in

the adjacent Anchorage 1° x 3° quadrangle (Winkler,

1992) clarified relations between terranes and characterized rocks at deep structural levels within the

Peninsular terrane. These maps and studies provide

integrated information regarding the geologic setting

of the Valdez quadrangle; most of the subsequent

descriptions of the quadrangle’s geology are derived

from these publications, and a simplified geologic

map, also derived from them, is used as a base for

maps A and B. A comprehensive bibliography of

geologic investigations in the Valdez quadrangle is

included in Winkler and others (1992).

GEOCHEMICAL STUDIES

Geochemical investigations in the Valdez

quadrangle have derived analytical results primarily

from reconnaissance stream-sediment and bedrock

sampling, with more detailed results available for just

a few areas. In a study of volcanogenic massive sulfide mineral deposits southeast of Valdez, Rose

(1965) reported results of analyses for 18 sulfidebearing rock samples and about 80 samples of

stream sedment. Jasper (1967) collected 102

stream-sedment and panned-concentrates samples

for analysis and visual examination from sites along
R

CI HARDS ON

H GI HWAY

WRANGELL–ST. ELIAS

NATIONAL PARK AND

PRESERVE

EDGERTON HIGHWAY

0 5 10 15 20 25 KILOMETERS

Chitina

Tonsina

LowerTonsina

Copper Center

Valdez

Tiekel

WRANGELL–ST. ELIAS

NATIONAL PARK AND PRESERVE

BORDER RANGES FAULT

CHUGACH 

MOUNTAINS

TARAL FAULT

BlackMountain

BO

R

DER

RANG

ES

F

A

ULT

CHITINA

FAULT

BORDER

RANGES

FAULT

TARAL FAULT

PENINSULAR TERRANE

COPPER RIVER LOWLANDS

TYPE

WRANGELLIA 

TERRANE

WRANGELL MOUNTAINS

SOUTHERN

WRANGELLIA

TERRANE

MARGIN

Mt. Wrangell

KimballPass

C H U G A C H M O U N T A I N S 

MarshallMountain

BernardMountain Bence

Mountain

Heavenly Ridge

CHUGACH

TERRANE

C

PRINCEWILLIAMTERRANE

ONTACT

FAULT

DustMountain

PENINSULAR

TERRANE

SOUTHERN

WRANGELLIA

TERRANE

MARGIN 

Haley

Creek

O'Brien Creek

Uranatina R.

Summit  Lake

Canyon Ck.

Lowe River Wortmanns Glacier

Woodworth Glacier

Marshall Glacier

Cheshnina Glacier

Jack Bay

Tebay Lakes 

Chitina River

Nelch ni a River

ul K it na R vi re

Nelchina Glacier

Tazlina Glacier

Columbia Glacier

Shoup

G al c ei r

Port Valdez

Tasnu n a River

Tiekel River

Tonsina Glacier 

Tonsina 

River

Tonsina Lake

COPPER RIVER

Kotsin a River

Dust Creek

Tsina Gl.

Cleave Creek Glacier

Valdez

 Arm

WorthingtonGlacier

nit ul K a aL ek

L anilzaT eka

COPPER RIVER

Little Bremner River

r B

me ner River

Valdez 

Glacier

Elliot Creek

GreylingLake 

Barnett e Creek

l K na l e en ce eh na Creek

Kaina Lake

147°00' 146°00' 145°00' 144°00' 62°00'

61°30'

61°00'

EXPLANATION

National Park and Preserve boundaryRoad

Fault—Dotted where concealedThrust fault—Sawteeth on upper plate.

Dotted where approximately located

GLENN H GI HWAY

OIL PIPELINE

TERMINUS

Kenney

Lake

3

Figure 1. Major physiographic and cultural features and lithotectonic terranes of the Valdez 1°x

3° quadrangle, Alaska. The quadrangle is underlain

 by rocks of the Wrangellia, Peninsular, Chugach, and Prince William terranes. The Wrangellia terrane is subdivided into the type Wrangellia terrane

 and the southern Wrangellia terrane margin.
    

   





























 







 





 











 





 



 























 

 



 

 











































 











































   



Jbr

Jbr

Jbr

Km

Mzm

Jbr



 Qs

 Qs

 Qs

 Qs

 Qs

 Qs

 Qs

 Qs

 Qs

Qs

 Qs

 Qs

QTw

Jc

Jc

144° 147° 62°

61°

Jc

Jc

Jc

Jc

COPPER RIVER

0 5 10 KILOMETERS 15 25 20

TARAL FAULT

QTw

QTw

Jbr Jbr

Jbr

Jbr

Jm

Km

Km

To

Jm

Jm

M mz

M mz

M mz

M mz

M mz M mz M mz

M mz M mz

M mz

M mz

Jbr Jbr Jbr

Jbr

M mz

M mz

R JTt R JTt

R JTt

R JTt

R JTt

R JTt

R JTt

JPc

JPc

JPc

JPc

JPhc

JPhc

JPhc

JPhc

JPhc

JPhc

JPhc

M mz



JPhc

JPhcJbr

g

g

g

g

g

g

g

g

g g

g

g

g

g

TKm

CHITINA FAULT

Port Valdez

Tazlina Lake

TARAL FAULT

SECOND LAKE FAULT

BORDER R NA

EG

SFAULT

ICEBERG FAULT

TAZL NI A

F AULT

ST. A

NNE FAUL T

BO

R

DER

RA

NGES FAUL T

Kv

Jc

JPhc

Kv

Kv

Kv

BORDER

RANGES

FAULT

BOR

DER

R

ANGES FA

ULT

CONTACT

FAULT Kvv

Kvv Kvv

Kvv 





















Kvv

Kvv

Kvv

Kvv

Kvv

Kvv

Kvv

Kvv

 Qs

Kvv

4
PENINSULAR TERRANE





zy

|{KmJbr

R JTt

Matanuska Formation (Cretaceous)Border Ranges ultramafic-mafic assemblage (Middle Jurassic)

Talkeetna Formation (Early Jurassic and Late Triassic?)

Contact

Fault—Dotted where approximately located

Thrust fault—Sawteeth on upper plate. Dotted where approximately located

PRINCE WILLIAM TERRANE 

Orca Group (Eocene and Paleocene)—Flyschoid sedimentary and tholeiitic

volcanic rocks

To

CHUGACH TERRANE

Melange (Tertiary or Cretaceous)

Valdez Group (Late Cretaceous)

Sedimentary rocksVolcanic rocks

McHugh Complex (Mesozoic) Greenschist and transitional blueschist facies metamorphic rocks (Jurassic 

or older)—As mapped includes schist of Liberty Creek and schist of Iceberg Lake

TKm

M m

Jm

z

Kv

Kvv

Glaciers and superglacial moraine

Surficial deposits, undivided (Quaternary)

g

Qs yz{|Jc 

yz{|QTw JPhc WRANGELLIA TERRANE Wrangell Lava (Holocene to Miocene) Chitina Valley batholith (Late Jurassic) Haley Creek metamorphic assemblage (Late Jurassic and 

Pennsylvanian and older?)

EXPLANATION

5

Figure 2. Generalized geology of the Valdez 1°x

3° quadrangle, Alaska. Modified from Winkler and others (1981b), Plafker and others (1989a, b), and 

Nokleberg and others (1989).
6

the Richardson and Edgerton Highways. Streamsediment, lake-sediment, and water samples were

collected from sites across most of the Valdez

quadrangle by the Los Alamos National Laboratory

for the U.S. Department of Energy’s National Uranium Resource Evaluation (NURE) program (Sharp

and Hill, 1978; D’Andrea and others, 1981; Los

Alamos National Laboratory, 1983). Detailed

stream-sediment sampling in the vicinity of the Spirit

Mountain nickel-copper prospect and stream-sediment and concentrate sampling around Bernard

Mountain were performed by Herreid (1970) and

Sutley and others (1990), respectively. Streamsedment and concentrate samples were collected

from 98 sites in the southern part of the quadrangle

as part of the Chugach National Forest RARE II

studies (Goldfarb and others, 1984). The most

comprehensive geochemical study was conducted in

conjunction with the AMRAP project, and included

bedrock, stream-sediment, and heavy-mineral-concentrate sampling and analysis from throughout the

quadrangle (Miller and others, 1982). Statistical analyses of all these data and descriptions of geochemical

anomalies in the Valdez quadrangle were completed

by Goldfarb and others (1995)—the principal source

of geochemical interpretation for this report. Goldfarb and others (1995) delineated 31 areas defined by

the presence of geochemical anomalies for various

suites of elements that characterize particular mineral

deposit types. Most of those areas are included

within the tracts of mineral-resource potential described in later sections of this report.

GEOPHYSICAL STUDIES

Shallow crustal geophysical investigations of

the Valdez quadrangle have been mostly reconnaissance in scope. Regional contouring of gravity data

for the entire Valdez quadrangle is included in a

1:2,500,000-scale Bouguer gravity map of the State

of Alaska (Barnes, 1977), and more detailed data

have been collected, contoured, and interpreted for

the southern one-third of the quadrangle in the area

of Chugach National Forest (Barnes and Morin,

1990). During regional studies of the Copper River

Basin, an aeromagnetic survey was flown over the

northern part of the Valdez quadrangle in 1954 and

1955 (Andreason and others, 1958), and the remainder of the quadrangle was flown in 1978 in conjunction with the AMRAP project. From these two surveys, Case and others (1986) published an interpretation of the aeromagnetics for the entire quadrangle. Other interpretations of aeromagnetic data from

parts of the quadrangle have been published separately (Andreason and others, 1964; Burns, 1982;

Plafker and others, 1989b). Case and others (1986)

found that the regional magnetic highs characteristically produced by particular bodies of rocks constituted indirect exploration guides for some types of

mineral deposits—particularly in areas where bedrock

is covered by unconsoldated deposits, glaciers, or

bodies of water. For example, high-amplitude

aeromagnetically postive features coincide with layered mafic and ultramafic igneous rocks that extend

nearly the full width of the northern part of the

quadrangle. These rocks locally host magmatic enrichments of nickel, chromium, copper, and

platinum-group elements (see subsequent sections);

even where the rocks are deeply covered, their

presence is substantiated by the aeromagnetic data.

In the 1980’s, geophysical investigations of

the deep crustal structure of southern Alaska along

the southern part of the TACT corridor provided

abundant data on earthquake seismicity (Page and

others, 1989), seismic reflection (Fisher and others,

1989) and refraction (Fuis and others, 1989), and

aeromagnetic and gravity fields (Campbell, 1991).

The combined data show that the upper crust beneath the Valdez quadrangle consists of sheets less

than 10 km thick of rocks from the Chugach,

Wrangellia, and Peninsular terranes underlain by

north-dipping thrust faults. Undulating reflectors at

depths between about 6 and 10 km are inferred by

Fuis and Plafker (1991) to be tonalitic plutons,

sources for the dikes and sills exposed in the Chugach

terrane at the land surface above that apparently are

concentrated in areas where low-sulfide gold-quartz

vein deposits formed.

LANDSAT IMAGERY

As part of the AMRAP project, Landsat images

of the Valdez quadrangle were evaluated to identify

lineaments and circular and arcuate features as possible aids to locating mineral-resource occurrences.

Although many linear, arcuate, and circular features

were observed, there apparently is no consistent

correlation between them and areas of known mineral occurrences (Le Compte, 1981) or areas

thought to have potential.

MINES, PROSPECTS, AND MINERAL

OCCURRENCES

Data from known mines, prospects, and mineral occurrences (fig. 3) were gathered from several

compilations on mining and prospecting in the Valdez

quadrangle, most notably Cobb (1979) and Jansons

and others (1984). Cobb (1979) compiled all published references to mines, prospects, and mineral

occurrences in the quadrangle, listing each by name

with a brief synopsis of the geology and mining history, if available. Jansons and others (1984) compiled mineral occurrences in the Chugach National

Forest, including the southern part of the Valdez

quadrangle, and included contemporary information

on mining claims filed with the Bureau of Land Management (BLM) and assessment studies by the former

U.S. Bureau of Mines. Additional descriptions of

mines and prospects in the Valdez quadrangle are

found in Cobb and Matson (1972), MacKevett and

Holloway (1977), and Winkler and others (1981a).

The latter report also provided a preliminary analysis

of general mineral deposit types in the quadrangle.
7

GEOLOGIC SETTING FOR MINERAL

RESOURCES

The Valdez quadrangle is underlain by four

distinctive, fault-bounded lithotectonic terranes of

contrasting stratigraphy, age, and structural and

metamorphic style. Each terrane also has associated

with it a characteristic suite of mineral commodities

and types of mineral deposits. From north to south,

the terranes are the Wrangellia, Peninsular, Chugach,

and Prince William terranes (figs. 1, 2). The

Wrangellia composite terrane, consisting of the late

Paleozoic or older amalgam of the Wrangellia and

Peninsular terranes (Plafker, 1987), was accreted to

the south-central Alaska margin by mid-Cretaceous

time (Csejtey and others, 1982; Hillhouse and

Grommé, 1984). Accretion and underplating of the

Chugach terrane against the backstop of the

Wrangellia composite terrane probably occurred

during much or all of Jurassic and Cretaceous time

(Plafker, 1987; Plafker and others, 1989b, 1994),

and the Prince William terrane was accreted by about

51 Ma (Plafker, 1987). Together the Chugach and

Prince William terranes form the Southern Margin

composite terrane (Plafker, 1990), one of the largest

subduction-related accretionary complexes in the

world (Plafker and others, 1994). Subsequent to

accretion, all four terranes were intruded by Eocene

felsic to intermediate dikes, sills, and small stocks. In

the northeastern part of the quadrangle, Miocene

and younger andesitic lavas were extruded on the

Wrangellia terrane, and summit craters on the Mt.

Wrangell shield volcano contain active fumaroles and

also occasionally emit ash.

WRANGELLIA TERRANE

The Wrangellia terrane (Jones and others,

1977) underlies the northeastern part of the Valdez

quadrangle and is bounded on the south by the Border Ranges fault system and on the west by the Taral

fault (fig. 2). The Wrangellia terrane is divided into

two distinct domains separated by the Chitina fault.

The southern domain, called the southern Wrangellia

terrane (Plafker and others, 1989b), consists of Early

Pennsylvanian to Jurassic plutonic and andesitic island

arc rocks and Early Pennsylvanian to Permian sedimentary and submarine volcanic rocks, all of which

have been penetratively deformed and metamorphosed to greenschist to lower amphibolite facies.

These metamorphic rocks, for which various names

have been used locally, are grouped into the Haley

Creek metamorphic assemblage. North of the

Chitina fault are rocks of the type Wrangellia terrane:

nearly unmetamorphosed Upper Paleozoic andesites

and plutonic rocks and Mesozoic rift-fill tholeiitic

basalts and shallow-marine calcareous and argillaceous sedimentary rocks. The most characteristic

rocks of the type Wrangellia terrane are the Triassic

Nikolai Greenstone and Chitistone Limestone—host

rocks for numerous copper-rich mineral deposits, including the Kennecott-type (discussed below). The

Upper Paleozoic rocks also host copper-rich

volcanogenic deposits—occurrences that are much

smaller than those hosted in the Mesozoic rocks that

typify Wrangellia. Prior to accretion of the Chugach

terrane along the southern margin of Wrangellia,

Upper Jurassic quartz monzodiorite, quartz diorite,

tonalite, and granodiorite of the Chitina Valley

batholith intruded the Wrangellia terrane, remobilizing pre-existing copper deposits in the older rocks.

The Jurassic plutons generally are intermediate to

mafic in composition; although they locally are

weakly enriched in molybdenum and copper, they

apparently are eroded below the level at which mineralized porphyry systems might have existed. Unconformably overlying the Wrangellia rocks in the

Valdez quadrangle are Holocene and Pleistocene

flows and pyroclastic rocks of the Wrangell Lava,

which are predominantly andesitic in composition, issued from the shield volcano of Mt. Wrangell (D.H.

Richter, in Miller and Richter, 1994). No hydrothermal deposits are assocated with these Neogene volcanic rocks.

PENINSULAR TERRANE

Along the northern edge of the Valdez quadrangle, west of and separated from the Wrangellia

terrane by the Taral fault and bounded on the south

by the Border Ranges fault, is the Peninsular terrane

(fig. 2). Within the quadrangle, the Peninsular terrane consists predominantly of the extrusive and intrusive phases of a Late Triassic to Middle Jurassic

intraoceanic magmatic arc (Barker and Grantz, 1982;

Burns, 1985; DeBari and Coleman, 1989). The extrusive rocks include bedded basaltic, andesitic, and

dacitic tuffaceous rocks, flows, shallow intrusions,

and volcanogenic sedimentary rocks of the Talkeetna

Formation. Although rocks representing relatively

shallow intrusive and extrusive levels of the Talkeetna

magmatic arc are widely exposed, only a few small

metal-bearing volcanogenic sulfide occurrences and

associated hydrothermal veins and breccias are

known to occur in this part of the quadrangle; no

major porphyry systems have been discovered. The

roots of the magmatic arc are exposed along the

southern edge of the Peninsular terrane along the

Border Ranges fault as a belt of mafic and ultramafic

plutonic rocks, informally named the Border Ranges

ultramafic-mafic assemblage (Hudson, 1983; Burns,

1985; DeBari and Coleman, 1989). The plutonic assemblage extends across the entire southern boundary of the Peninsular terrane and consists principally

of layered gabbronorite, perdotite, and dunite.

Magmatic enrichments of chromium, copper, nickel,

and platinum-group elements are associated with the

deep-seated ultramafic-mafic assemblage at several

places. A klippe of metamorphosed Peninsular terrane, consisting of Jurassic amphibolite, orthogneiss,

and layered gabbro, is found south of the Border

Ranges fault in the Chugach terrane, between the

Tazlina and Nelchina Glaciers (fig. 2). Cretaceous

clastic sedimentary rocks deposited in a fore-arc

basin, the Matanuska Formation, crop out in the extreme northwest corner of the quadrangle.
Chitina

Tonsina

LowerTonsina

Copper Center

Valdez

           

             

   

       

6

7

9

23

12

14

16

22 18

31

8

11 10

19

20

13

5 4

1

25 26

27

28

24

30

29

30

30

30

32

8 8

8

36

37

33

34

35

Port Valdez 

district

17

21

Elliot  Ck. Kotsina 

district

Tonsina 

district

15

BORDER RANGES FAULT

TARAL FAULT

BlackMountain

BO

R

DER

RA

N

G

ES

F

A

ULT

CHITINA

FAULT

BORDER

RANGES

FAULT

TARAL FAULT

PENINSULAR TERRANE

TYPE

WRANGELLIA 

TERRANE

WRANGELL MOUNTAINS Mt. Wrangell

MarshallMountain

BernardMountain

BenceMountain

Heavenly Ridge

C

PRINCEWILLIAMTERRANE

ONTACT

FAULT

DustMountain

PENINSULAR

TERRANE

SOUTHERN

WRANGELLIA

TERRANE

MARGIN 

ICEBERG FAULT

SOUTHERN

WRANGELLIA

TERRANE

MARGIN

SOUTHERN

WRANGELLIA

TERRANE

MARGIN

Lowe River

Woodworth Glacier

Cheshnina Glacier

Jack Bay

Tebay Lakes 

Chitina River

Nelch ni a River

ul K it na R vi re

Nelchina Glacier

Tazlina Glacier

Columbia Glacier

Port Valdez

Tasnu n a River

Tiekel River

Tonsina Glacier 

Tonsina 

River

Tonsina Lake

COPPER RIVER

Kotsin a River

Dust

Creek

Tsina Gl.

Cleave Creek Glacier

Valdez

 Arm

WorthingtonGlacier

nit ul K a aL ek

L anilzaT eka

COPPER RIVER

Little Bremner River

r B

me ner River

Valdez 

Glacier

GreylingLake 

Barne t te Creek

l K na l e en ce eh na Creek

Kaina Lake

0 5 10 15 20 25 KILOMETERS

147° 146° 145° 144° 62°

61°

30'

61°

2

TAZLINA

FAULT

3

8

Central sulfide 

belt
EXPLANATION

Mine—Identified by numberProspect—Identified by numberOccurrence—Identified by numberPlacer—Identified by numberMining district—Area includes numerous mines and prospectsGlaciers and superglacial moraineFault—Approximately locatedThrust fault—Approximately located.

Sawteeth on upper plate

 



Mines, prospects, and occurrences 1 Cliff mine 2 Ramsey-Rutherford mine 3 Gold King mine 4 Orion prospect

5 Curly-Kidney prospect6 Benito Creek prospect7 Kaina Lake prospect8 Kimball Pass prospects9 Quartz Creek mine

10 Opal mine11 Fivemile Creek occurrence12 Hundell Creek prospect13 Worthington Glacier prospect14 Little Bremner River placer15 Boulder Creek placer16 Tasnuna River placer17 Unnamed placers in central  sulfide belt. 18 Midas mine

19 Jack Bay copper prospect20 Jack Bay prospect21 Addison-Powell prospect22 Wortmann Glacier occurrence23 Tsina Glacier occurrence24 Marshall Mountain prospect25 Blackney prospect26 Surprise prospect27 Divide Creek prospect28 Falls Creek prospect29 Spirit Mountain prospect30 Summit Lake prospects31 Heavenly Ridge occurrence32 Liberty Falls prospect 33 Sheep Hill prospect34 Dust Mountain prospect35 Bernard Mountain prospect36 Barnette Creek occurrence37 Scarp occurrence

9

Figure 3. Metallic mines, prospects, and occurrences in the Valdez 1°x

3° quadrangle, Alaska. These mostly consist of 

small gold-bearing quartz veins. They also include placer gold; copper sulfide-dominant volcanogenic, magmatic, and 

Kennecott-type deposits; and podiform chromite mines, prospects and (or) occurrences.
10

CHUGACH TERRANE

The Chugach terrane, which forms most of

the remaining southern two-thirds of the Valdez

quadrangle, is separated from the Wrangellia and

Peninsular terranes by the Border Ranges fault

system. The Chugach terrane consists of three major

fault-bounded sequences (fig. 2). From north to

south, they include: (1) Jurassic and older greenschist and blueschist of the informally named schists

of Liberty Creek and Iceberg Lake; (2) Upper Triassic to Lower Cretaceous melange and broken formation of the McHugh Complex; and (3) Upper Cretaceous flysch and oceanic basaltic rocks of the Valdez

Group.

The schist of Liberty Creek forms a belt 28 km

long along the northern margin of the Chugach terrane between Dust Creek and the Copper River.

This unit is intensely deformed and consists of greenschist and minor blueschist. Relict textures and geochemistry suggest that it originally was an oceanic assemblage of basalt flows, breccias, and tuffs, and minor sedimentary rocks, which may have orignated as

the subduction assemblage related to magmatism in

the Talkeetna arc (Plafker and others, 1989b, 1994).

A fault-bounded slab of greenschist and blueshist 40

km long by as much as 2 km wide (the schist of Iceberg Lake) is enclosed within the McHugh Complex

along the Iceberg fault between Klutina Lake and

Nelchina Glacier (Winkler and others, 1981b).

Faulted against the schist of Liberty Creek

along the Second Lake fault or against the Border

Ranges ultramafic-mafic assemblage along the Border Ranges fault is the McHugh Complex, a structurally-dismembered melange and broken formation

composed predominantly of tholeiitic pillowed basalt

and fragmental mafic volcanic rocks, with less abundant pelitic sedmentary rocks, radiolarian chert, and

carbonate units. Locally, the McHugh Complex contains olistostromal blocks derived from the Wrangellia

and Peninsular terranes, with which it now is tectonically juxtaposed. Rocks of the McHugh Complex

generally are metamorphosed to prehnite-pumpellyite facies. They are interpreted to have formed by

sedimentary and structural mixing of oceanic and arcderived rocks during Jurassic and Cretaceous convergence between an oceanic plate and the southern

margin of the Wrangellia-Peninsular composite terrane.

The third and most widespread unit of the

Chugach terrane consists of flysch and tholeiitic basalt

of the Upper Cretaceous Valdez Group. The flysch

facies consists of an extremely thick and lithologically

montonous sequence of interbedded argillite, siltstone, sandstone, and conglomeratic sandstone. The

minor basalt facies, which is exposed principally

along the southern edge of the quadrangle, consists

of pillow basalt, pillow breccia, and aquagene mafic

tuff. These metavolcanic rocks commonly contain

lenses of massive to disseminated pyrite, pyrrhotite,

chalcopyrite, cubanite, and sphalerite (Winkler and

others, 1981a)—volcanogenic sulfide deposits of the

Besshi- and Cyprus-types. In the Valdez quadrangle,

the Valdez Group is highly deformed and regionally

metamorphosed to greenschist facies. Metamorphic

grade increases eastward, culminating in the Cordova

and Bering Glacier 1° x 3° quadrangles in a schist and

gneiss complex cored by migmatite and anatectic

plutons. The metamorphism and plutonism are

Eocene in age (Hudson and others, 1979; Hudson

and Plafker, 1982) and occurred during accretion of

the Valdez Group against the melange to the north.

In the Valdez quadrangle, this regional high-temperature, low-pressure thermal event is manifested by

felsic to intermediate dikes, sills, and plugs that are

present throughout the Chugach terrane, but are

particularly common in the Valdez Group.

Mesothermal or low-sulfide gold-quartz veins are

equally widespread in the greenschist facies

metasedimentary rocks and are associated with the

hypabyssal intrusions in many places in the Chugach

terrane (Goldfarb and others, 1986; Goldfarb, 1989).

PRINCE WILLIAM TERRANE

Rocks of the Prince William terrane, which

crop out in the southwest corner of the Valdez

quadrangle, are a Paleogene accretionary assemblage, which has been strongly deformed and underplated against the Valdez Group along the Contact fault system (fig. 2). These Paleogene rocks, the

Orca Group, consist principally of low-grade metamorphosed flysch—argillite, siltstone, and conglomerate—which were deposited in deep-sea fans adjacent to a convergent continental margin (Winkler and

Plafker, 1993). Tholeiitic basalt, pillow breccia, and

mnor mafic tuff commonly are interbedded with the

sedimentary rocks. In the Valdez quadrangle, these

mafic volcanic sequences are relatively thin, but to

the south and southwest, in the Cordova and Seward

quadrangles, they are voluminous and form—at

Knight Island in western Prince William Sound—a

complete ophiolitic sequence with sheeted dikes, intrusive gabbro, and sheared ultramafic rocks (Richter,

1965; Tysdal and Case, 1979; Nelson and others,

1985). At Rua Cove on Knight Island in the Seward

quadrangle, and in the vicinity of Ellamar and Landlocked Bay in the Cordova quadrangle, the ophiolitic

rocks and interbedded argillaceous sequences enclose

volcanogenic massive sulfide deposits of the Cyprusand Besshi-types, which have had large past production of copper and contain significant unmined resources (Nelson and others, 1984). No similar occurrences are known in rocks of the Orca Group in the

Valdez quadrangle, however.

RESOURCE ASSESSMENT METHODS

This assessment reviews known metalliferous

mineral deposits and evaluates the potential for

undiscovered deposits by describing and classifying

the types of mineral deposits present and delineating

areas likely to contain additional undiscovered deposits of the classified types. Known and potential

mineral deposits in the Valdez quadrangle are classified according to eight descriptive mineral deposit

models, as shown on table 1. Most exploration and

much small-scale mining took place in the Valdez
11

Table 1. Classification of mineral deposit types for the Valdez 1° x 3° quadrangle, Alaska

[Known mineral deposit types are those present in the quadrangle, which—in most cases—have been mined or

thoroughly prospected. Postulated mineral deposit types are those that are not known to occur within the

quadrangle, but for which geologic features or geochemical anomalies commonly associated with the deposit

type are present]

KNOWN MINERAL DEPOSIT TYPES

Vein deposits:

Low-sulfide, gold-quartz veins (precious-metal veins)

Massive sulfide deposits:

Volcanogenic massive sulfide deposits

Kennecott-type deposits

Magmatic deposits:

Layered and podiform chromite deposits

Nickel-copper sulfide deposits

Placer deposits:

Precious-metal placers

POSTULATED MINERAL DEPOSIT TYPES

Vein deposits:

Polymetallic veins (base- and precious-metal veins)

Stockwork deposits:

Porphyry copper-molybdenum stockworks and veins

quadrangle between the late 1890’s and circa 1920.

For that time, the surface prospecting was relatively

thorough, but little information was published, and

production data seldom were made available. Reported descriptions of claims and operations are

brief, imprecise, and qualitative. There has been no

major mining and very little modern exploration in

the quadrangle. Given these serious limitations in

available information, our assignments of mineral deposit model types are tenuous and general.

Nonetheless, we have identified tracts whose characteristics are favorable for additional occurrences of

the eight types. Since our model types are so

poorly constrained by available information, we do

not make distinctions between less favorable (or

“permissive”) and more favorable (or “prospective”)

tracts, nor do we estimate numbers of undiscovered

deposits. The tracts we delineate may be a hybrid of

the “permissive” and “prospective” concepts, and

with so little data, there is no rigorous way to distinguish them, nor to produce a quantitative estimation.

The resulting areas of mineral-resource potential are shown on maps A and B, and levels of resource potential and certainty are assigned to each of

the tracts. All known occurrences within the

mapped tracts are characterized on tables 2 through

5 (tables 2–5 begin on p. 26 of this pamphlet).

In our assignments, we conform to tradtional

definitions of mineral-resource potential and certainty

(Taylor and Steven, 1983). High mineral-resource

potential exists where geologic, geochemical, and

geophysical characteristics favorable for resource accumulation are known to be present, or where

enough of these characteristics are present to give

strong evidence that mineral concentration has taken

place. (These conditions normally are met in tracts

that enclose known mineral occurrences of the

specified types.) Moderate mineral-resource

potential exists where geologic, geochemical, or

geophysical characteristics favorable for resource accumulation are known or can be reasonably inferred

to be present, but where evidence of specific mineral

concentration is less certain. Low mineral-resource

potential exists in areas where geologic, geochemical, or geophysical characteristics permit deposits of

a classified type to be present, but where no evidence of mineral concentration is present. The certainty of the assigned level is based on the availability

and reliability of relevant information, which ranges

from clearly defining the level of mineral-resource

potential (certainty level D)—a condition met in very

few cases in the Valdez quadrangle—to inadequate

or unavailable information on potential mineral resources (level A ). Intermediate levels of certainty, C

and B, indicate that good or suggestive information,

respectively, is available to assign a likelihood of

mineral-resource occurrences. Implicit within our

use of these defintions is the assumption that any occurrences that are found will conform to the sizes

and grades of other known deposits of the classified

type, where such a grade-tonnage model has been

developed.

The following sections of the report discuss

examples of each deposit type in the quadrangle,

briefly elaborating characteristics that are likely to

make nearby areas of the quadrangle prospective for

additional as-yet undiscovered occurrences.

KNOWN MINERAL DEPOSIT TYPES

VEIN DEPOSITS

Low-sulfide gold-quartz veins (precious-metal veins)

(table 2; map A)

Lode gold deposits are widespread in the

Valdez quadrangle, with gold occurrences having

been found in all four lithotectonic terranes (map A).
12

However, most gold occurrences are present in the

lower to middle greenschist facies rocks of the

Valdez Group. In quadrangles adjacent to the Valdez

quadrangle, gold-producing districts also are located

in Valdez Group rocks: the Girdwood district

(Anchorage quadrangle) (Park, 1933); Port Wells,

Hope-Sunrise, and Moose Pass districts (Seward

quadrangle) (Johnson, 1914, 1915; Tuck, 1933); and

Nuka Bay district (Seldovia quadrangle) (Richter,

1970). An estimated 132,400 ounces (oz) of gold

have been produced from lode deposits in these

quadrangles, including 61,646 oz from the Valdez

quadrangle (Jansons and others, 1984). All known

lode precious-metal production in the Valdez quadrangle has come from rocks of the Valdez Group,

mostly from a few large gold-quartz vein systems

mined near Valdez—the Cliff, Ramsey-Rutherford,

and Gold King mines (Johnson, 1915). The Cliff

mine (tract G-1, site G44) produced more than twice

as much lode gold as any other mine in the Prince

William Sound area—51,740 oz, as well as 8,153 oz

Ag. In the Port Valdez district (fig. 3), the RamseyRutherford (site G27) was second, having produced

5,375 oz Au and 1,194 oz Ag, and the Gold King

(site G52) was third, having produced 1,997 oz Au

and 187 oz Ag (Jansons and others, 1984, Appendix). Analyses of extensive chip and grab samples

from these deposits during U.S. Geological Survey

and U.S. Bureau of Mines investigations in the early

1980’s (Goldfarb and others, 1984; Jansons and

others, 1984) indicate that many veins average between 0.2–2.0 oz/ton Au and 0.2–1.0 oz/ton Ag;

several properties in the Port Valdez district have

between several hundred and several thousand tons

of reserves (Jansons and others, 1984).

Within the Valdez Group rocks, gold-bearing

quartz veins occur in shear zones and joints and as

saddle reefs, in metasedimentary rocks and intermediate-composition dikes and stocks that have undergone brittle deformation. The veins commonly contain native gold, pyrite, arsenopyrite, chalcopyrite,

sphalerite, galena, and occasionally stibnite or scheelite. Total sulfide content is low, generally only a few

percent (Pickthorn, 1982; Goldfarb, 1989). Although these veins are as thick as several meters in

many places, they seldom are continuous for more

than 100 m and pinch and swell markedly along

strike. In some occurrences, the veins may contain

economic concentrations of silver, which, therefore,

is a potential byproduct resource (Goldfarb and

others, 1992). Nonmetallic gangue minerals are

predominantly quartz, but include calcite, albite,

chlorite, and limonite. Near-surface oxidation is

present locally, but veins generally are not deeply

weathered and oxidized enrichment zones are not

typical. The gold is free-milling.

Gold-bearing quartz veins of the type found in

rocks of the Valdez Group have commonly been

refered to as orogenic metamorphic-hosted veins

(Bohlke, 1982), low-sulfide gold-quartz veins

(Berger, 1986), or mesothermal veins (Nesbitt and

others, 1986). Examples of this deposit type include

the Juneau gold belt in Alaska and the California

Mother Lode (Goldfarb and others, 1997).

However, the Juneau gold belt and the Mother Lode

are spatially assocated with major crustal lineaments,

whereas the deposits in rocks of the Valdez Group

do not exhibit such fundamental structural control.

This absence of fluid-focussing crustal lineaments may

explain the generally lower tonnages of deposits

hosted by the Valdez Group, although their grades

are relatively high.

The genesis of these mesothermal gold-bearing veins has engendered considerable debate.

Mitchell (1979) first suggested a metamorphic dewatering model for vein formation in the Valdez Group;

however, Mitchell and others (1981) and Silberman

and others (1981) interpreted limited stable isotope

and fluid inclusion data from the Hope-Sunrise district

as indicating ore deposition by meteoric water at

shallow depths. These authors estimated vein formation at temperatures of approximately 190° C and

pressures of 1–25 bars, and classified these veins as

epithermal deposits. Pickthorn (1982) and Pickthorn

and Silberman (1984) suggested that initial fluids in

veins in the Port Valdez district formed from metamorphic dewatering and that vein deposition occurred from a mixture of boiling metamorphic and

meteoric fluids. Goldfarb and others (1986) interpreted fluid inclusion and stable isotope data for goldbearing veins throughout the Valdez Group and determined that ore deposition was from a non-boiling

fluid at temperatures of at least 210°–280° C and

pressures of 1–1.5 bars. They related ore genesis to

metamorphic devolatilization within deeper parts of

an accretionary wedge, where the higher pressures

and temperatures characterized a mesothermal, not

epithermal, environment. The vertical extent of the

gold-bearing veins, at least 2 km, by itself is suggestive of a mesothermal environment. In the Valdez

district, limited K-Ar geochronologic data indicate

that the regional metamorphic mineral assemblages,

the vein mineral assemblages, and the minerals in discordant felsic dikes all span the same Eocene period

of time, circa 53–47 Ma (Goldfarb and others, 1986;

Plafker and others, 1989b), strongly suggestive of a

common regional genesis. Haeussler and others

(1995) suggested that subduction of an oceanic

spreading center may have been the ultimate driving

force for both magmatism and gold-related hydrothermal activity.

Within the Valdez quadrangle, magnetic and

gravity data provide no direct indication of areas of

gold mineralization within the Valdez Group or other

rock units. In a few places, gold-bearing veins cut

mafic metavolcanic rocks and are marked by weak

gossans (map A, tract G-4); the metavolcanic rocks

engender a weak positive aeromagnetic signature.

However, most of the known gold-bearing deposits

(table 2) are hosted by metasedimentary rocks and

are located in areas of deep magnetic basement (5–

10 km), varable magnetization, and shallow gravity

gradents; thus, they cannot be associated directly

with features responsible for the magnetic or gravity

anomalies.

Geologic criteria are also of limited use in gold

exploration in the Valdez quadrangle. The lack of

major structural features associated with the
13

occurrences and the fairly uniform metamorphic

grade of the Valdez Group rocks do not allow for direct geologic targeting of favorable areas. Throughout the Valdez Group, however, there does appear

to be a spatial relation between areas of felsic dikes

and gold mineralization. This relation may indicate

areas that were more prone to brittle deformation

and (or) more conducive to dike and vein formation.

Geochemical data are the best indicators of areas favorable for the presence of gold-bearing quartz

veins, but are nonetheless not everywhere reliable.

For example, stream-sediment and panned-concentrate sampling in the Valdez quadrangle failed to delineate the Tonsina district (map A, tract G-2), where

deposits within the Valdez Group have had known

minor lode production. This probably is due to the

very steep topography and active alpine glaciation in

the district, and the small tonnage typical of the deposits.

Several tracts of high potential for lode-gold

deposits in the Valdez Group have been identified

(map A, tracts G-1 through G-3). Tract G-1, just

north of the town of Valdez, is the Port Valdez district, an area approximately 45 km by 15 km with

numerous mines, prospects, and occurrences. Most

lode gold produced in the Valdez quadrangle was

from this district (Nelson and others, 1984, table 2).

Grab samples of vein quartz from the Alice (site

G46), Cliff (G44), Little Giant (G32), and Millionaire

(G35) mines contain as much as 5,000 parts per million (ppm) Au, 700 ppm Ag, 11,000 ppm As, as

well as anomalous Bi, Cd, Cu, Hg, Pb, Sb, W, and

Zn (Goldfarb, 1989). Stream-sediment and concentrate samples anomalous in Ag, Au, Co, Cu, Fe, Ni,

or Pb (±As, Mo, Zn) also characterize this tract and

expand the borders of the district to include new favorable ground to the northwest along Divider

Mountain and Pandora Peak (Goldfarb and others,

1995). Jansons and others (1984) also reported the

occurrence of a small gold-bearing quartz vein in the

extension (site G56). Based on the existence of producing mines and the extent of geochemical anomalies, tract G-1 is assigned a high potential, certainty

level D (H/D), for lode gold and associated silver resources in small quartz veins.

Tract G-2 (map A) is the Tonsina district, a

300-km2 area just southeast of Tonsina Lake in the

center of the quadrangle that also has been identified

as having high potential, certainty level D (H/D), for

lode gold resources. Although several mines in this

district have recorded production, very few streamsediment or concentrate samples were anomalous in

elements, such as Ag, As, Au, Cu, Pb, and Zn, that

are indicative of gold mineralization; the boundary of

this tract is based principally on the presence of

mines and prospects. Goldfarb and others (1995)

speculated that this lack of geochemical anomalies

may reflect either the presence of very fine grained

gold in the source lodes or relatively limited outcrops

of the gold-bearing quartz veins.

A large tract in the south-central Valdez

quadrangle, centered around Cleave Creek Glacier

and extending eastward across the Copper River

(map A, tract G-3) has been identified as having a

high potential, certainty level B (H/B), for undiscovered lode gold deposits, based on geochemical

anomalies in stream-sediment and concentrate samples. Concentrate samples collected from near the

toe of the Cleave Creek Glacier contain as much as

700 ppm Ag, >20,000 ppm As, and >1,000 ppm

Au. Microscopically visible grains of native gold and

sulfide minerals are relatively abundant in many of

the samples (Goldfarb and others, 1995). East of the

Copper River, concentrate samples contain anomalous gold but less commonly silver or arsenic. Although no mineral occurrences have been recognized in this tract, a placer gold prospect along the

West Fork of the Little Bremner River was reported

by Moffit (1914), and a quartz vein sampled by Miller

and others (1982) contained 200 ppm As, 500 ppm

Cu, and 150 ppm Ni. This tract also is underlain by

metasedimentary rocks of the Valdez Group.

Tracts G-4 through G-8 (map A) also contain

geochemical anomalies suggestive of areas of lode

gold occurrences within the Valdez Group, and have

been assigned a moderate potential, certainty level C

(M/C). These tracts of resource potential are defined

by anomalous concentrations of gold, commonly

with silver, in analyses of stream-sediment and

heavy-mineral-concentrate samples (Goldfarb and

others, 1995). Tract G-4 along the southern edge of

the quadrangle is an extensive belt enclosing anomalous gold and base-metal-bearing samples collected in

an area of mixed metasedimentary and metavolcanic

rocks. Although most mines and prospects in this

tract are massive sulfide occurrences, several gold

quartz veins have been explored. A vein sample

from the Orion prospect (site G60), at the west end

of the tract, contained 26,000 ppm As, 300 ppm

Cd, 16 ppm Sb, and 5,200 ppm Zn (Goldfarb and

others, 1995). Anomalous gold was detected in

concentrate and stream-sediment samples from several sites in the tract. Several concentrate samples

from below Sulphide Gulch and near Canyon Slough

contained 700–1,000 ppm Au. A concentrate sample from the outwash of Marshall Glacier contained

detectable gold, and is the only concentrate sample

from the Valdez quadrangle that contained detectable

antimony (500 ppm). Mcroscopic examination of

these samples also detected visible gold (Goldfarb and

others, 1995). Tracts G-5 through G-8 also are defined by samples containing anomalous gold and assocated indicator elements, such as Ag, As, Pb, Zn,

and Cu (Goldfarb and others, 1992).

South of the settlement of Tonsina in the

vicinity of Kimball Pass, several gold-bearing quartz

veins have been prospected (MacKevett and Holloway, 1977), and stream-sediment samples from

this tract (map A, tract G-9) contained 0.05–0.95

ppm Au (Miller and others, 1982). Quartz veins in

windows of Valdez Group that are exposed between

traces of the strongly folded Border Ranges fault are

likely sources of this gold. This tract has been assigned a moderate potential, certainty level B (M/B),

for gold resources. Based upon geochemical sampling and the presence of the scattered prospects,

most of the southern part of outcrop areas of the

Valdez Group (tract G-10) also has been assigned a
14

moderate potential, certainty level B (M/B), for lode

gold resources. Although samples from this tract

contain little or no detectable gold, elements generally considered to be indicative of gold occurrences,

such as Ag, As, Cu, Pb, W, and Zn, are commonly

elevated in analyses (Miller and others, 1982).

Because rocks of the Valdez Group are permissive

for the formation of lode gold deposits, all the

remainder of the Valdez Group (tract G-11) has been

assigned a low potential, certainty level B (L/B), for

containing undiscovered occurrences of lode gold.

Other indications of lode gold resources in the

Chugach terrane occur in rocks of the McHugh

Complex. Just west of Chitina, mines and prospects

of the Opal group (map A, tract G-12, site G6) consist of several quartz veins less than 1 m thick that

contain arsenopyrite, pyrite, galena, and sphalerite,

and yield values of gold and silver (MacKevett and

Holloway, 1977). Winkler and others (1981a) considered these veins to be cogenetic with small

Eocene plutons. This tract is considered to have a

moderate potential, certainty level C (M/C), for gold

resources in quartz veins. Two other tracts underlain

by rocks of the McHugh Complex have been identified by geochemical sampling as favorable for goldbearing veins. Tract G-13, south of Tonsina, and

tract G-14, along Klanelneechena Creek in the

northwestern part of the quadrangle, yield concentrate samples with anomalous gold and other elements (Miller and others, 1982) suggestive of

precious-metal mineralization. These tracts are assigned a moderate potential, certainty level B (M/B),

and a low potential, certainty level B (L/B), respectively, for gold resources in small vein systems.

South of the Contact fault in rocks of the Orca

Group, several sulfide-bearing quartz veins are present, indicating a possibility of potential lode gold

resources (Winkler and others, 1981a; Nelson and

others, 1984). Stream-sediment and concentrate

samples that are weakly anomalous in Au (0.5 ppm),

Ag, As, and Cu (Goldfarb and others, 1995) also may

reflect the presence of gold-bearing quartz veins in

this tract (map A, tract G-15). Elsewhere, rocks of

the Orca Group generally lack gold-bearing quartz

veins. The only known occurrences are in the

McKinley Lake area of the Cordova quadrangle,

where veins are proximal to a granitic stock

(Goldfarb and others, 1992). Rocks of the Orca

Group are geochemically similar to those of the

Valdez Group, and, if exposed to low- to moderategreenschist facies metamorphic conditions similar to

the Valdez Group, may be favorable for formation of

low-sulfide gold-quartz veins. Because of the lack of

strong geochemical indicators, tract G-15 is considered to have low potential, certainty level B (L/B),

for undiscovered lode gold occurrences.

Northeast of Chitina in the Wrangell Mountains, several gold-bearing quartz veins are present in

low-grade metamorphic rocks of the Skolai Group

(Wrangellia terrane). At Benito Creek (map A, tract

G-16, site G5), a 1-m-thick quartz vein containing

pyrite, arsenopyrite, chalcopyrite, tetrahedrite, and

native gold was exposed for 200 m along strike.

Although no production has been recorded, this vein

was reputed to have contained beautiful gold-quartz

specimens (Moffit, 1915; Moffit and Mertie, 1923).

To the north, placer gold occurrences have been reported at the mouth of Copper Creek (tract G-17,

site G3) (Winkler and others, 1981a), and one concentrate sample contained 5 ppm Au (Goldfarb and

others, 1995). A Jurassic granodioritic pluton intrudes Triassic carbonate rocks nearby; unrecognized

skarn mineralization is one possible source for the

placer gold. Alternatively, several copper prospects

near the headwaters have byproduct gold or silver

(Moffit and Mertie, 1923), and also are possible

sources. Other stream-sediment samples in this tract

(G-17) contain anomalous antimony, an indicator of

possible gold enrichment (Goldfarb and others,

1995). The Benito Creek area (G-16) is assigned a

moderate potential, certainty level B (M/B), and the

Copper Creek area (G-17) is assigned a low potential, certainty level B (L/B), for gold resources in

low-sulfide quartz veins. North of these areas on the

west flank of Mt. Wrangell, several bulldozer cuts

have been made on lode gold claims in iron-stained

talc schist and greenschist of the Haley Creek metamorphic assemblage (tract G-18). Apophyses of the

Jurassic Chitina Valley batholith crop out nearby and

may have induced the formation of small, weakly

mineralized vein systems in the metamorphic rocks.

Analyzed rock samples from this prospect contained

no detectable gold, but did have as much as 5,000

ppm Ba and 5 ppm Ag (Miller and others, 1982).

The tract is assigned a low potential, certainty level B

(L/B), for precious-metal resources in small vein

systems.

A lone occurrence of gold in rocks of the

Peninsular terrane in the northwestern part of the

Valdez quadrangle (map A, tract G-19) was reported

by the U.S. Bureau of Mines (1980). Little is known

about this location, except that several lode claims

were staked along a contact between the Talkeetna

Formation and a Jurassic intrusion (Winkler and

others, 1981a). This tract has been assigned a low

potential, certainty level B (L/B), for gold resources.

MASSIVE SULFIDE DEPOSITS

Volcanogenic massive sulfide deposits

(table 3; map B)

The south-central part of the Valdez quadrangle is underlain by interbedded metasedimentary and

mafic metavolcanic rocks of the Valdez Group. The

metavolcanic rocks are interpreted as upper levels of

oceanic basaltic crust, formed at a spreading center,

with which sediments derived from a nearby continental margin magmatic arc were interlayered

(Plafker and others, 1989b). A broad and generally

gentle gravity high, termed the “Prince William

Sound high” (Barnes and Morin, 1990), is associated

with much of this area and is attributed to the relative

abundance of metavolcanic rocks. The metavolcanic

rocks are moderately magnetic, in marked contrast

to the enclosing nonmagnetic metasedimentary

rocks; thus, although they occur only in thin sequences, they impart a characteristic positive
15

magnetic high on the regional aeromagnetic coverage (Case and others, 1986), and can be traced confidently beneath glaciers along the southern edge of

the quadrangle.

Massive and semi-massive stratiform ironcopper-zinc sulfide deposits are present at scattered

locations within, or proximal to, the mafic metavolcanic rocks (Crowe and others, 1992). The Midas

mine (map B, tract C-1, site C3), the fourth largest

copper producer in the Prince William Sound region

and the largest copper producer in rocks of the

Valdez Group, is located south of Valdez, as are

several significant prospects (Winkler and others,

1981a). The two principal ore horizons at the Midas

mine produced over 500 tons of Cu, and 2,569 oz

Au and 15,157 oz Ag were produced as byproducts

(Rose, 1965). Jansons and others (1984) estmated

additional reserves of 62,000 tons grading 1.6 percent Cu. The ore bodies are hosted princpally in

shear zones in metasedimentary rocks (Johnson,

1915), which are interbedded with tholeiitic basalt

breccias and tuffs and tuffaceous sedimentary rocks.

Ore at the Midas mine consisted principally of chalcopyrite, pyrite, pyrrhotite, sphalerite, and minor

galena, and also contained as much as 0.42 oz/ton

Ag and 0.062 oz/ton Au (Rose, 1965). These occurrences are classified either as Besshi-type massive

sulfide deposits if the lodes are hosted by metasedimentary rocks or Cyprus-type if the lodes are in

metavolcanic rocks (Nelson and Koski, 1987; Crowe

and others, 1992).

Stream-sediment samples from near the southern margin of the quadrangle are seldom anomalous

in elements indicative of nearby massive sulfide deposits, but panned-concentrate samples are consistently anomalous in Ag, As, Co, Cu, Fe, and Ni. Bi,

Pb, and W also are anomalous at some sites

(Goldfarb and others, 1995). Concordant lenses and

disseminations of sulfide minerals, as well as discordant sulfide-bearing quartz veins in shear zones, are

common in the metavolcanic rocks of this area. This

trend of anomalous geochemical samples forms a

northern extension of the informally named “Central

Sulfide Belt” of the Cordova quadrangle immediately

to the south (Goldfarb and others, 1992). The tract

proximal to the Midas and Addison-Powell properties

(map B, tract C-1) is assigned a high potential, certainty level D (H/D), for the occurrence of volcanogenic massive sulfide deposits with resources of

copper and byproduct gold, silver, lead, or zinc.

Eastward and westward extensions of the metavolcanic rocks and associated geochemical anomalies

(tracts C-2 and C-3) are considered to have moderate potential, certainty level C (M/C), for volcanogenic massive sulfide deposits. Samples of sulfide-bearing metavolcanic rocks and veins near

Wortmanns Glacier (tract C-3, site C5) are characterized by as much as 1.5 ppm Ag, 500 ppm Cr, 1,500

ppm Cu, 15 percent Fe, 7 percent Mg, 300 ppm

Pb, and 7,000 ppm Zn (Miller and others, 1982).

Several other geochemically anomalous tracts

associated with metavolcanic rocks of the Valdez

Group have been identified. Winkler and others

(1981a) described sulfide-bearing quartz veins and

disseminated sulfide minerals in mafic metavolcanic

rocks near the toe of Tsina Glacier (map B, tract C4, site C6). This tract contains metavolcanic rocks

similar to those in the vicinity of the Midas and Addison-Powell properties and is considered to have a

moderate potential, certainty level C (M/C), for

undiscovered resources of copper in volcanogenic

massive sulfide deposits. In the south-central and

southeastern parts of the quadrangle, anomalous

geochemical samples and known occurrences of sulfide-bearing metavolcanic rocks (Goldfarb and others,

1995; Winkler and others, 1981a) define a discontinuous arc of tracts (C-5 through C-7) with low potential, certainty level B (L/B), for volcanogenic massive

sulfide deposits.

Volcanogenic copper deposits of a different

character occur in pre-Cretaceous rocks at many

places north of the Border Ranges fault in the Valdez

quadrangle. In the southern domain of Wrangellia,

south of the Chitina fault, Pennsylvanian and Permian

mafic flows and volcanclastic rocks host disseminated

and massive sulfide deposits in at least four locations.

The host rocks, weakly foliated greenstones of the

Strelna Metamorphics, are interpreted to have

formed in the early tholeiitic phase of a late Paleozoic

intraoceanic arc, the Skolai arc (Richter and Jones,

1973). Just north of the Tebay fault along the eastcentral edge of the quadrangle (map B, tract C-8),

copper- and iron-rich sulfide bodies are present at

the Falls Creek, Divide Creek, Surprise Creek, and

Blackney prospects (sites C7–C10, respectively)

(Moffit, 1914; MacKevett and Holloway, 1977;

Winkler and others, 1981a). Both the Blackney and

Surprise Creek prospects occur near the margins of

large Jurassic tonalite intrusions, which may account

for both the brecciation and the hydrothermal alteration that characterize them. These prospects consist

principally of veins of chalcopyrite and pyrite, and

are much smaller than the volcanogenic deposits in

the Prince William Sound region. Concentrate samples from tract C-8 generally contain 200–300 ppm

Cu, and one sample from the headwaters of Taral

Creek contained 10,000 ppm Cu and 5 ppm Ag

(Goldfarb and others, 1995). This highly anomalous

sample probably represents material weathered directly from the Blackney prospect, which contains a

pyrite-chalcopyrite vein 0.5 m wide that extends for

at least 60 m (Moffit, 1914). The tract is thought to

have moderate potential, certainty level C (M/C), for

undiscovered small copper lodes.

Records of the U.S. Bureau of Mines (1980)

include a location of patented lode claims for copper

in veins near Iron Creek (map B, tract C-10, site

C11). We did not visit this site; host rocks for the

prospect apparently are Upper Paleozoic metavolcanic rocks close to the concealed trace of the

Chitina fault and also close to outcrops of Jurassic

monzodiorite exposed in the canyon of the Kotsina

River. Goldfarb and others (1995) did not show

geochemical anomalies that might indicate nearby

occurrences in this tract. The tract is considered to

have low potential, certainty level B (L/B), for small

copper lodes.
16

Another tract of moderate potential for volcanogenic copper deposits is present in rocks of the

type Wrangellia terrane north of the Chitina fault

(map B, tract C-9). In the Wrangell Mountains, east

of the Kotsina River, numerous copper occurrences

define the Kotsina district (Moffit and Mertie, 1923;

Van Alstine and Black, 1946). The occurrences

occupy complexly faulted and sheared zones in the

Middle and Upper Triassic Nikolai Greenstone, and in

the lowermost part of the overlying Upper Triassic

Chitistone Limestone. The occurrences in the Nikolai

Greenstone probably were generated by the same

processes that formed the rich lodes in the Chitistone

Limestone at the Kennecott mines to the east in the

McCarthy quadrangle (MacKevett, 1976—see next

section). However, since the greenstone clearly is

the source of the copper and since most greenstonehosted occurrences in the Valdez quadrangle are not

proximal to lodes in the overlying carbonate rocks,

they are described briefly here.

The Nikolai Greenstone was formed by voluminous, largely subaerial effusions of tholeitic basalt

at low paleolatitudes (Hillhouse, 1977), either in a rift

(Jones and others, 1977) or above an elongate mantle plume (Richards and others, 1991). The greenstone is intrinsically elevated in copper—geochemical

analyses, formation-wide, average 155 ppm Cu

(MacKevett and others, 1997). At the time of subaerial eruption, the copper probably was incorporated in a silicate mineral phase, then leached by lowtemperature brines, which may have formed during

and following deposition of the overlying Upper

Triassic limestones (MacKevett and others, 1997). In

the Valdez quadrangle, copper deposits in the Nikolai

Greenstone generally consist of discordant veins and

adjacent disseminations of bornite and chalcopyrite,

with lesser pyrite, covellite, and enargite. Veins

generally are thin and discontinuous, averaging about

5–10 cm wide and extending for only tens of meters

laterally. Isolated masses of bornite and chalcopyrite

as large as 0.5 m by 1.5 m have been found along

some of the veins (Moffit and Mertie, 1923), but no

large or high-grade deposits have been found and no

tonnage or grade information has been published. In

tract C-9, in the vicinity of Copper and Elliott

Creeks, some deposits contain slightly elevated gold

and silver values, as well as native copper (Moffit,

1915; Moffit and Mertie, 1923). Although underground workings in tract C-9 may total over 700 m,

there is no record of production. Stream-sediment

samples in the tract contain as much as 340 ppm Cu,

and concentrate samples as much as 2,000 ppm Cu

(Goldfarb and others, 1995). This tract is considered

to have moderate potential, certainty level C (M/C),

for undiscovered copper resources in small veins and

lodes in the Nikolai Greenstone.

Tracts C-11 and C-12 (north of the Kotsina

and Cheshnina Rivers, respectively) are geologically

similar to tract C-9 and therefore permissive for the

formation of volcanogenic copper resources in the

Nikolai Greenstone. These tracts have been

prospected, but generally lack geochemical anomalies that would be expected in the vicinity of volcanogenic deposits. They are considered to have

low potential, certainty level B (L/B), for volcanogenic sulfide deposits.

Two tracts of low potential, certainty level B

(L/B), for copper resources in disseminated volcanogenic deposits have been identified by geologic

mapping in the Peninsular terrane. In the northwestern part of the quadrangle, the Heavenly Ridge

prospect (map B, tract C-14, site C20) is a large

iron-stained pyritic zone in Lower Jurassic volcanic

and volcaniclastic rocks of the Talkeetna Formation.

Newberry (1986) considered this occurrence to be a

volcanogenic massive sulfide deposit. Although there

is no recognized copper anomaly, the site may have

some potential. An area similarly pyritized volcanic

and volcaniclastic rocks of the Talkeetna Formation

also occurs in the north-central part of the quadrangle at Willow Mountain (tract C-13, site C19), where

weak iron- and copper-staining are distributed over a

large area (Winkler and others, 1981a), and weak

geochemical anomalies for copper and zinc have

been reported (Miller and others, 1982).

Kennecott-type deposits (table 3; map B)

Within a few years after the discovery of the

Bonanza lode near McCarthy in 1900, every outcrop

of the contact between the Nikolai Greenstone and

the Chitistone Limestone in the southern Wrangell

Mountains—the stratgraphic interval in which the rich

deposits of the Kennecott mines near McCarthy occur—had been prospected thoroughly (Mendenhall,

1905). Although numerous occurrences were noted

in the Nikolai Greenstone throughout the region, the

richest lodes were found to be confined to the lower

part of the overlying Chitistone Limestone, principally in the vicinity of the Kennecott mines.

MacKevett and others (1997) provided a thorough descriptive and genetic model for stratabound

copper deposits of the type occurring at the Kennecott mines in the McCarthy quadrangle about 60

km east of the eastern edge of the Valdez quadrangle. The following summary is abstracted from their

definitive paper.

Following formation of the copper-enriched

Nikolai Greenstone, carbonate sediments were deposited in a Late Triassic marine embayment upon

the low-relief volcanic platform in an arid, nearequatorial environment, forming the Chitistone Limestone and overlying units. Local basins in the embayment contained sabkha-facies carbonate sediment

rich in sulfates and organic matter, which became

concentrated in evaporative brines. These brines circulated downward through joints and solution cavities

into the underlying basalt. Subsequently, Late Jurassic and Early Cretaceous regional orogeny promoted

further circulation of the brines, scavenging copper

from the basalt and forming small early veins and

disseminations in the basalt. When the circulating

copper-rich brines migrated into solution fissures and

breccias in the lower parts of the overlying carbonate rocks, however, they formed large and rich

lodes, which are surrounded by envelopes of hydrothermal dolomite. In the McCarthy quadrangle to

the east, where the carbonate sequence is thickest
17

and the sabkha facies rocks are most extensive,

enormous northeast-striking stratabound lodes (such

as those at the Bonanza, Jumbo, Mother Lode, and

Erie mines) form upward-tapering wedges as large as

580 m long, 50–60 m high, and 0.5–15 m wide at

the base—the dimensions of the main Bonanza vein.

This one ore body produced 720,000 tons of

chalcocite-rich ore grading 13.44 percent copper;

the ore also contained about 0.77 oz/ton silver.

Somewhat smaller subparallel orebodies were spaced

about 60 m apart, plunging northeastward essentially

parallel to dips of the host Chitistone Limestone.

In the Valdez quadrangle, small bornite-chalcopyrite-malachite-pyrite veins are hosted in the

Chitistone Limestone near its contact with the Nikolai

Greenstone at the Swayze prospect on Elliott Creek

(map B, tract C-9, site C12) and at the Ammann and

Mullen prospects on Copper Creek (tract C-9, sites

C16, C17, respectively). The mineralized veins apparently are continuations of sulfide-bearing veins in

the underlying Nikolai Greenstone and do not widen

into large lodes within the calcareous rocks (Moffit

and Mertie, 1923). In 1943, reserves at the Mullen

property were calculated to be about 1,300 tons at

1.55 percent copper (Van Alstine and Black, 1946)—

a figure that is dwarfed by any of the known Kennecott-type deposits of the McCarthy area. Thin sequences of the Chitistone Limestone also overlie the

Nikolai Greenstone on both the north and south sides

of Elliott Creek. Although many copper-bearing

veins have been prospected in the greenstone, none

are known to extend upward into the limestone, nor

are any independent lodes or veins known in outcrops of the Chitistone Limestone. In the Valdez

quadrangle, the Chitistone apparently lacks the critical sabkha, organic-shale, and fetid-limestone facies

of the lower member that are characteristic of the

McCarthy area (Armstrong and MacKevett, 1982).

Furthermore, the calcareous sequence in the Valdez

quadrangle is one-tenth to one-third as thick as in the

vicinity of the Kennecott mines (Moffit, 1938)—a

thickness that is unlikely to generate a sufficient volume of copper-mobilizing brines to create large deposits, even if evaporite minerals had been present

originally in the Chitistone in the Valdez quadrangle.

Nonetheless, there is a slight possibility that small

stratabound lodes of the Kennecott-type remain to

be discovered in Upper Triassic carbonate rocks of

the northeastern part of the Valdez quadrangle (map

B, tracts C-9, C-11, C-12). A moderate potential,

certainty level C (M/C), is assigned to tract C-9 because prospects are present, and a low potential,

certainty level B (L/B), is assigned to tracts C-11 and

C-12, which lack prospects.

Except for local occurrences of native copper

in brecciated flow tops, amygdaloidal fillings, or rare

disseminations, “volcanogenic” deposits hosted in the

Nikolai Greenstone share several characteristics with

Kennecott-type ores (MacKevett and others, 1997).

Curiously, however, no Nikolai-hosted deposits are

known within about 10 km of the main Kennecott

mines. Most deposits in the Nikolai, like those in the

overlying carbonate rocks, follow northeast-trending

structures and contain minerals with low

sulfur/copper ratios, but generally form only small

veins of short lengths. Wallrock alteration adjacent

to veins, unless there are nearby plutons, is negligible. Silberman and others (1980) presented compelling evidence that Nikolai-hosted veins formed at

the same time and in equilibrium with regional

metamorphism of the Nikolai at about 112±11 Ma.

[That terrane-wide metamorphism is presumed to

have resulted from the accretion of the Wrangellia

composite terrane to the Alaskan continental margin.]

Presumably, formation of the Nikolai veins constituted an early phase of a continuum that led to much

richer and more voluminous copper deposition in

more favorable superjacent carbonate host rocks.

Thus, it is possible that some Nikolai-hosted veins

represent feeders for Kennecott-type deposits.

Whether the deposits are hosted in greenstone or

carbonate rocks, however, the presence of volcanic

rocks enriched in copper was critical for ultimate

genesis of the deposits.

MAGMATIC DEPOSITS

Layered and podiform chromite deposits

(table 4; map B)

Several areas of chromium occurrences are

found associated with layered mafic and ultramafic

plutons along the Border Ranges fault in the Valdez

quadrangle. The rocks are part of the Border

Ranges mafic-ultramafic assemblage (Hudson, 1983),

which exposes deep, primitive levels of the Peninsular terrane, formed as a Late Triassic–Middle Jurassic

intraoceanic island arc (Burns, 1985). The Bernard

Mountain (map B, tract M-1, site M3), Sheep Hill (or

Dust Mountain/West) (site M2), and Dust Mountain

(site M1) prospects southeast of Tonsina, are located

on conspicuous, tectonized and cumulate ultramafic

bodies within a belt 40 km long and as wide as 4 km

that contains discontinuous outcrops of strongly deformed dunite, pyroxenite, peridotite, and garnetbearing layered gabbronorite separated by glacial

valleys. This belt is called the Tonsina ultramaficmafic sequence (Winkler and others, 1981a; Plafker

and others, 1989b). Regional aeromagnetic data

show that the sequence is continuous beneath the

Quaternary cover and dips north to northwest toward a concealed contact with the Nelchina River

gabbronorite, which makes up the rest of the Border

Ranges mafic-ultramafic assemblage (Case and others, 1986).

At a prospect on the south side of Bernard

Mountain (site M3), chromite occurs as sporadic pods

and contorted masses 1–15 cm thick and 15–75 cm

long in a tectonized harzburgite (Newberry, 1986).

This prospect contains an estimated 5,000–15,000

tons at 5 percent Cr2O3, with a Cr:Fe ratio of 2.5

(Newberry, 1986, table 2). In contrast, at a

prospect on the north side of Bernard Mountain,

eight chromitite-rich bands 0.3–1.5 m thick are exposed in a 300-m-wide zone in cumulate dunite.

This prospect contains an estimated 100,000–

200,000 tons at 11 percent Cr2 O3, and the Cr:Fe

ratio is more favorable at 3.0 (Newberry, 1986,
18

table 2). Foley and Barker (1985, table 1) identfied a

total resource of 343,000 tons at 5 percent Cr2O3 at

deposits at the southwest end of the mountain with

Cr:Fe ratios from 1.9 to 2.6. These deposits apparently are in cumulate dunite (Newberry, 1986, figs.

11–12). Foley and Barker (1985) noted numerous

additional small chromite occurrences on Bernard

Mountain. Inasmuch as the large deformed ultramafic body crops out over a 2 km by 3.5 km area

(Hoffman, 1974), other unevaluated chromite occurrences are likely.

At Sheep Hill (“Dust Mountain” of Newberry,

1986—map B, site M2), two poorly exposed

chromite-bearing zones in cumulate dunite occur on

the west and east sides of the hill, but are separated

by about 1,000 m of barren perdotite. According to

Newberry (1986, table 2), layers 0.6–1.6 m thick

and at least 15–25 m long in these zones contain an

estimated 3,000–10,000 tons at 7 percent Cr2O3

with Cr:Fe at 1.2. Foley and Barker (1985, table 2)

indicate that these deposits contain >26,000 tons at

5 percent Cr2 O3 with Cr:Fe at 1.9.

According to Berg and Cobb (1967), a

prospect at Dust Mountain (east of Dust Creek—map

B, site M1), exposes a massive body of chromite as

much as 3 m thick and 25 m long, apparently in tectonized harzburgite (Newberry, 1986). Berg and

Cobb (1967) reported hand samples assaying as high

as 57 percent Cr2O3, with a range in Cr:Fe ratio in

the chromite of 1.20–3.06. In contrast, Foley and

Barker (1985) and Newberry (1986) reported only

low-grade zones of disseminated or thinly banded

chromite on Dust Mountain, with bulk samples containing only 2.6 percent Cr2 O3 with Cr:Fe at 1.1.

Foley and Barker (1985) reported that samples of

dunite from Dust Mountain are more magnetic than

from Bernard Mountain and Sheep Hill. They speculated that lower Cr:Fe ratios at Dust Mountain may

reflect increased magnetite and decreased chromite

in the spinel mineral fraction.

Anomalous concentrations of Ni (1,000–5,000

ppm), Co (150–200 ppm), Cu (1,000 ppm), and

platinum-group elements have been detected at the

Bernard Mountain, Sheep Hill, and Dust Mountain

sites (Mulligan, 1974; MacKevett and Holloway,

1977; Miller and others, 1982), both in dunite and in

associated peridotite or pyroxenite layers. The platinum-group element contents of chromite concentrates are as much as 3.4 ppm at Dust Mountain, 1.0

ppm at Sheep Hill, and 1.7 ppm at Bernard Mountain (Foley and others, 1987, 1989). At Dust

Mountain, one chromite-rich segregation contained

10.5 ppm Pd and 7.9 ppm Pt and chrome spinel

bands in pyroxenite also contain as much as 610 ppb

Au (Foley and others, 1987). Stream-sediment

samples are anomalous in Cr (as much as 5,000

ppm), Ni (as much as 1,000 ppm), and Fe (as much

as 15 percent), and clearly define this area of chromite occurrences (Goldfarb and others, 1995). Tract

M-1 is assigned a high potential, certainty level D

(H/D), for chromite-enriched magmatic deposits and

likely also contains byproduct platinum-group elements. Magmatic sulfide minerals, pyrite, marcasite,

chalcopyrite, and lesser pentlandite occur in

overlying garnet-bearing gabbronorite (or “granulite”) layers. Selected rock samples from near

benchmark “Scarp,” at the northeast end of tract M1, contain 2–6 percent sulfide minerals (Newberry,

1986).

There are two additional areas of anomalous

chromium: (1) a tract extending eastward from the

Bernard Mountain–Dust Mountain area along the

Second Lake fault (tract M-2); and (2) at the northwest edge of the quadrangle just east of Nelchina

Glacier (tract M-3). Although these occurrences are

located within areas of melange (McHugh Complex

or younger melange unit), the source of the

chromium is considered to be structural slabs of serpentinized ultramafic rocks of the Peninsular terrane

that have been brought up along the faults and incorporated in melange in the fault zones (Winkler and

others, 1981b). Some rock samples from tract M-3

contain >5,000 ppm Cr and as much as 1,000 ppm

Ni (Goldfarb and others, 1995). Tracts M-2 and M-3

are assigned a moderate potential, certainty level B

(M/B), for undiscovered resources of chromium and

associated nickel in magmatic deposits.

Nickel-copper sulfide deposits (table 4; map B)

Several nickel-copper sulfide prospects are located between the Tebay and Border Ranges faults

at the eastern edge of the Valdez quadrangle. These

prospects are located on small mafic and ultramafic

sills in metamorphosed schist and limestone of the

Strelna Metamorphics of the southern Wrangellia

terrane (Winkler and others, 1981b; Plafker and

others, 1989b). The deposits are magmatic in origin

and consist of massive and disseminated sulfide minerals—pyrite, pyrrhotite, pentlandite, chalcopyrite,

bravoite, and sphalerite—in the mafic and ultramafic

intrusions. Hand samples of massive sulfide minerals

have contained as much as 7.61 percent Ni, 1.56

percent Cu, 0.18 percent Co, and 2 oz/ton Ag

(Overbeck, 1920; Kingston and Miller, 1945;

Herreid, 1970); geochemical analyses show as much

as 15 ppm Ag, 2,000 ppm Co, >20,000 ppm Cu,

>5,000 ppm Ni, and 0.4 ppm Au (Goldfarb and

others, 1995). Associated sulfide-bearing quartz

veins contain >10,000 ppm As, 3,000 ppm Cu,

>5,000 ppm Ni, and 7.0 ppm Pd, and an ultramafic

rock sample contains 50 ppb Pt (Miller and others,

1982). Estimates of inferred resources at the Spirit

Mountain prospect (map B, tract N-1, site N2) are

6,500 tons of material averaging 0.7 percent Ni and

0.5 percent Cu (Cornwall, 1968). Tract N-1 is assigned a high potential, certainty level C (H/C), for

undiscovered copper and nickel resources in small

magmatic sulfide deposits.

Several other areas considered to have potential for magmatic copper-nickel resources have been

identified in rocks of the Peninsular terrane. In the

northwestern corner of the quadrangle, streamsediment samples collected from Klanelneechena

Creek and tributaries,which are underlain by a klippe

of layered gabbro and ultramafic rocks, were

anomalous in Fe, Co, Cu, Cr, or V—the values for

Co, 150 ppm, and Cu, 300 ppm, were the highest
19

reached for stream-sediment samples in the quadrangle (Goldfarb and others, 1995). This tract, N-2,

is assigned a moderate potential, certainty level B

(M/B), for magmatic nickel-copper resources. Two

other anomalous tracts in gabbroic rocks of the

Peninsular terrane, N-3 east of Tonsina and N-4 in

the northwest corner of the quadrangle, also have

been identified by geochemical sampling. Layered

gabbronorite of the Tonsina ultramafic-mafic sequence in the vicinity of the “Scarp” benchmark,

tract N-3, contained as much as 1,000 ppm Ni and

1,000 ppm Cu in rock samples with visible pyrite,

marcasite, and chalcopyrite (Newberry, 1986; Goldfarb and others, 1995). In the Barnette Creek tract,

N-4, a sulfide-bearing mafic dike in the Nelchina

River gabbronorite contains as much as 15 percent

Fe, 10 percent Mg, 5 ppm Ag, 1,000 ppm Co,

1,500 ppm Cr, 28,000 ppm Cu, 3,000 ppm Ni, and

0.55 ppm Au (Miller and others, 1982). Newberry

(1986) described layers in the Barnette Creek area,

at a relatively high stratigraphic level within the

4,000-m-thick Nelchina River gabbronorite, that

contained from 2 to 7 percent interstitial sulfide

minerals, principally pyrrhotite and chalcopyrite, but

with minor pentlandite as well. His analyses of

sulfide-bearing rock showed anomalous Cu (2 percent) and Ni (240 ppm), but insignificant amounts of

Au, Pt, and Pd. Intersttial grains of sulfide minerals,

chiefly pyrrhotite, and possibly chalcopyrite and

pyrite, are disseminated in layered gabbronorite of

the Border Ranges ultramafic-mafic assemblage in

many places; slightly elevated concentrations locally

characterize gossans. Inasmuch as gold and

platinum-group elements are enriched in magmatic

sulfide layers in layered mafic-ultramafic plutonic

complexes elsewhere in the world, Newberry (1986)

speculated that such enriched horizons might occur

stratigraphically lower in the Nelchina River gabbronorite. No such occurrences have been located

downsection to the south, but the terrane is rugged

and very difficult to explore; prospecting has been

minimal. Tracts N-3 and N-4 are both considered to

have low potential, certainty level B (L/B), for undiscovered copper and nickel occurrences, with possible byproduct resources of gold or platinum-group

elements.

PLACER DEPOSITS

Precious-metal placers (table 2; map A)

Approximately one-half of the gold produced

from the Valdez and adjacent Seward, Anchorage,

and Cordova 1° x 3° quadrangles has been from

placer deposits (Nelson and others, 1984). However, almost all of this placer gold production was

from the Girdwood district and from districts on the

Kenai Peninsula (Tysdal, 1978), not from placers in

the Valdez quadrangle. Much of the Valdez quadrangle is characterized by very steep topography and

active alpine glaciation. Unlike the fluviatile environments of the placer districts at Girdwood and on

the Kenai Peninsula, the predominantly fluvioglacial

environments of the Valdez quadrangle are generally

unfavorable for the development of economic placer

deposits. In areas underlain by rocks of the Valdez

Group, most drainages near known lode gold mines

also were placered, but generally the deposits were

low-grade and the gold was very fine (Winkler and

others, 1981a). In the Chugach National Forest, an

investigation of potential placer gold resources was

carried out by the U.S. Bureau of Mines (Jansons and

others, 1984). Of 20 sites examined, 7 with gold

values ranging from 0.0023 to 0.028 oz/yd3 were

considered to have moderate potential, certainty

level C (M/C), for development. On map A and

table 2 these are: Tasnuna River (PL-7), Cleave

Creek (PL-8), Bench Creek (PL-5), Brown Creek

(PL-4), Solomon Gulch (PL-3), Salmon Creek (PL-2),

and Mineral Creek (PL-1). One site, Marshall Glacier

(PL-6), tested at 0.14 oz/yd3 , and was considered by

the U.S. Bureau of Mines to have high potential, certainty level C (H/C), for development (Jansons and

others, 1984). Gold-bearing placers were identified

in the early 1900’s on the Little Bremner River just

downstream from its unnamed source glacier (site

PL-9) in a relatively inaccessible basin where quartz

veins with anomalous gold values also were discovered (Moffit, 1914). A short distance to the west

near the headwaters of Dewey Creek, which drains

to the Copper River from the same unnamed glacier,

gold-bearing placers also occur (Miller and others,

1982). This short, steep drainage apparently was

not prospected during the early 1900’s. In the Little

Bremner drainage, prospecting was thorough, but

values were low. The prospectors soon moved

eastward to richer placers discovered on Golconda

Creek in the McCarthy quadrangle. Site PL-9 is

given a low potential, certainty level C (L/C), for

unworked resources of precious-metal placers.

Because rocks of the Valdez Group are permissive as bedrock sources for gold in placers, all

drainages (exclusive of sites PL-1 to PL-9) underlain

by rocks of the Valdez Group are considered to have

a low potential, certainty level B (L/B), for undiscovered resources of placer gold. In areas outside of

Valdez Group bedrock, all drainages underlain by

bedrock areas with anomalous gold values also are

considered to have a low potential, certainty level B

(L/B), for undiscovered resources of placer gold.

POSTULATED MINERAL DEPOSIT TYPES

VEIN DEPOSITS

Polymetallic veins (base- and precious-metal veins)

(table 5; map A)

According to generally accepted models (Cox

and Singer, 1986), polymetallic veins can be distinguished from low-sulfide gold-bearing quartz veins

by their greater content of sulfide minerals and by

their inclusion of a broader suite of base and ferrous

metals in addition to the typical precious metals. In

polymetallic veins, Zn, Cu, and Pb values will be significantly higher, and Fe and Mn generally also will

be much higher than in typical precious-metal veins.

Because of the increased presence of base and
20

ferrous metals, weathering of polymetallic veins typically produces gossans. In the steep, rapidly eroding

terrane of southern Alaska, however, where oxidation zones generally are thin (if present at all), even

weak gossans seldom form over polymetallic veins.

Inasmuch as the geochemical signature of polymetallic veins includes metals that also are anomalous in

many precious-metal veins, the two vein types really

may represent a continuum. The presence of felsic

dikes in the vicinity of both types of geochemical

signatures in the Valdez quadrangle also supports the

inferred genetic link between low-sulfide goldbearing quartz veins and polymetallic veins.

Three tracts in the Valdez quadrangle (map A,

tracts P-1 through P-3) are considered to have potential for polymetallic vein deposits, based on geochemical sampling. No occurrences are known

presently. In two tracts south of Klutina Lake (P-1

and P-2), heavy-mineral-concentrate and streamsediment samples contained anomalous amounts of

Ag, Fe, As, Cu, Mo, Pb, W, or Zn, including several

of the highest values reported in the quadrangle

(Goldfarb and others, 1995). These tracts are underlain by metasedimentary rocks of the Valdez Group.

Minor intercalated metavolcanic rocks and abundant

felsic dikes also are present. The third tract (P-3) is

east of the Tazlina Glacier and is underlain by rocks

of the McHugh Complex. Concentrate and sediment

samples contained anomalous Zn and Sb, and less

commonly Ag, Mg, Co, Ni, Cu, Cr, or Ti. Goldfarb

and others (1995) suggested that these suites of elements possibly indicate polymetallic veins in source

rocks for the sediment. All three tracts are assigned

a low potential, certainty level B (L/B), for the occurrence of undiscovered polymetallic veins.

STOCKWORK DEPOSITS

Porphyry copper-molybdenum stockworks and veins

(table 5; map B)

Two sulfide-bearing occurrences assocated

with plutons have been prospected in the last 30

years in the Valdez quadrangle. In the east-central

part of the quadrangle near the mouth of the Chitina

River (map B, tract I-1), disseminations and small

clots of chalcopyrite and molybdenite have been

found in an Upper Jurassic biotite granodiorite pluton

near its contact with greenstone of the Strelna

Metamorphics; the occurrence was tentatively considered to be a porphyry system by MacKevett and

Holloway (1977). However, stockwork quartz

veining and alteration that might be indicative of extensive hydrothermal alteration are notably lacking

(Winkler and others, 1981a). In the northwestern

part of the quadrangle, sulfide-bearing quartz veins

occur in iron-stained, brecciated Talkeetna Formation

near its contact with a small Jurassic or Eocene pluton (tract I-2), but the veining and gossan are only

very local. Analyses of stream-sediment samples

from drainages in the adjacent area have some minor

enrichments in molybdenum, copper, and zinc (Miller

and others, 1982). Although we regard undiscovered porphyry-related deposits as unlikely, we assign

a low potential, certainty level B (L/B), to tracts of

small extent that include both of these occurrences.

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Open-File Report, August 1980, scale

1:250,000.

Van Alstine, R.E., and Black, R.F., 1946, Copper

deposits of the Kotsina-Kuskulana district,

Alaska: U.S. Geological Survey Bulletin 947–

G, p. 121–141.

Winkler, G.R., compiler, 1992, Geologic map, cross

sections, and summary geochronology of the

Anchorage quadrangle, southern Alaska: U.S.

Geological Survey Miscellaneous Investigations

Series Map I–2283, scale 1:250,000.

Winkler, G.R., Goldfarb, R.J., and Borden, J.C.,

1995, Map showing geology and geochemically anomalous areas, Valdez 1° x 3° quadrangle, south-central Alaska, in Goldfarb, R.J.,

Borden, J.C., and Winkler, G.R., Geochemical

survey of the Valdez 1° x 3° quadrangle,

south-central Alaska: U.S. Geological Survey

Bulletin 2084, 77 p., 1 sheet, scale

1:250,000.

Winkler, G.R., Goldfarb, R.J., Pickthorn, W.J., and

Plafker, George, 1992, The Alaska Mineral

Resource Assessment Program—Background

information to accompany geologic and mineral-resource maps of the Valdez quadrangle,

south-central Alaska: U.S. Geological Survey

Circular 1087, 25 p.

Winkler, G.R., Miller, R.J., MacKevett, E.M., Jr.,

and Holloway, C.D., 1981a, Map and summary table describing mineral deposits in the

Valdez quadrangle, southern Alaska: U.S.

Geological Survey Open-File Report 80–892–

B, 2 sheets, scale 1:250,000.

Winkler, G.R., and Plafker, George, 1993, Geologic

map and cross sections of the Cordova and

Middleton Island quadrangles, southern Alaska:

U.S. Geological Survey Miscellaneous Investigations Series Map I–1984, scale 1:250,000.

Winkler, G.R., Silberman, M.L., Grantz, Arthur,

Miller, R.J., and MacKevett, E.M., Jr., 1981b,

Geologic map and summary geochronology of

the Valdez quadrangle, southern Alaska: U.S.

Geological Survey Open-File Report 80–892–

A, 2 sheets, scale 1:250,000.
drainages favorable for Table 2. Characteristics of tracts favorable for low-sulfide gold-quartz veins and drainages favorable for

ka precious-metal placers in the Valdez 1° 

x 3° quadrangle, Alaska—CONTINUED

esence of quartz

ar structures;

mmodities Geochemical Geophysical Site no./Names Location Principal references

sent anomalies present features T., R.

LOW-SULFIDE GOLD-QUARTZ VEINS (MAP A)—CONTINUED

Ag Ag, As, Au, Ba, None noted G26 T8S, R5W U.S. Bureau of Mines (1980)

Bi, Cd , Co, Cu, G27/Ramsey-Rutherford T8S, R5W Johnson (1915), Moffit (1954)

Fe, Mo, Ni, Pb, G28/Pinochle T8S, R5W Johnson (1915)

Sb, W, Zn. G29/Rose Johnson T8S, R5W Johnson (1915)

G30/Valdez Bonanza, Ibex, Valdez T8S, R6W Brooks (1912), Brooks (1922), Johnson (1915)G31/Ethel, Blue Ribbon T7S, R6W Brooks (1912), Johnson (1915), Smith (1930)G32/Mountain View, July, Little T7S, R6W Johnson (1915), Smith (1937) Giant, Mountain King, Rose, Star.G33/Alaskan T8S, R6W Johnson (1915)G34/Quitsch T7S, R6W Johnson (1915G35/Hercules, Chesna, Monte Carlo, T7S, R6W Brooks (1912), Johnson (1915), Johnson Sunshine, Slide, Millionaire. (1919a).G36/Forty-Five, High Grade T8S, R6W Johnson (1915)G37/Big Four T7S, R7W Johnson (1915), Smith (1937)G38/McCallum T8S, R7W Johnson (1916), Johnson (1918)G39/Alaska Gold Hill T8S, R7W Johnson (1919a)G40/Owl/Thompson-Ford T8S, R7W Johnson (1915)G41/Guthrie and Belloli T8S, R7W Johnson (1915)G42/Bunker Hill, Seacoast Mining Co. T8S, R8W Johnson (1915)G43/Cube T8S, R7W Johnson (1915), Johnson (1919a)G44/Cliff T9S, R8W Johnson (1915), Moffit (1954)G45/Gold Bluff, Sealey-Davis T8S, R8W Johnson (1915)G46/Alice T8S, R8W Johnson (1915)G47/IXL, Shoup Bay Mining Co., T8S, R8W Brooks (1912), Johnson (1915) Silver Gem, Spanish.G48/Palmer T8S, R8W Brooks (1912)G49/Bluebird, Whistler T8S, R8W Brooks (1912), Johnson (1915)G50/Big Four, Hecla T8S, R8W Brooks (1912)G51/Cameron-Johnson, Minnie, T8S, R8W Johnson (1912), Johnson (1918) Olson, Rambler.G52/Gold King T8S, R8W Johnson (1915)G53/Bessie Williams T8S, R9W Johnson (1915)G54/National, Mayfield T8s, R9W Johnson (1915), Johnson (1916)G55/Rough and Tough, Ruff and T8S, R9W Smith (1939) Tuff, Thompson.G56/Divider Mountain T7S, R9W Jansons and others (1984)

Ag Ag, As, Au, Cu, None noted G12 T5S, R2W U.S. Bureau of Mines (1980)

 Fe, Pb. G13/Quartz Creek T5S, R1W Moffit (1918)

G14/Telluride, Wetzler T6S, R1W Moffit (1918), Moffit (1935)G15/Squaw Creek T6S, R1E U.S. Bureau of Mines (1980)G16/Tiekel T6S, R1E MacKevett and Holloway (1977)G17/Glacier Creek T6S, R1W U.S. Bureau of Mines (1980)G18/Knowles T6S, R1W Moffit (1935)G19/Eagle T6S, R1W Moffit (1935)G20/Ross T6S, R1W Moffit (1935)G21/Portland T7S, R1E Moffit (1918)G22/Reis T7S, R1E Moffit (1918)

Ag Ag, As, Au, B, None noted None noted

Be, Co, Cu, Ni,

Sn, W, Zn.

Ag (±Cu, Ag, As, Au, B, Ba, Positive G59/Curly Kidney T10S, R8W Johnson (1919b)

 Zn). Bi, Cd,Co, Cu, aeromagnetic G60/Orion T10S, R7W Johnson (1919b)

Fe, Mn, Mo, Ni, anomalies G61/Patten Mining Co., Golden, T9S, R7W Johnson (1919b), Mulligan (1974)

Pb, Sb, V, W. over areas of Happy Days.

 mafic meta- volcanic rocks.
drainages favorable for Table 2. Characteristics of tracts favorable for low-sulfide gold-quartz veins and drainages favorable for

ONTINUED precious-metal placers in the Valdez 1° 

x 3° quadrangle, Alaska—CONTINUED

mmodities Geochemical Geophysical Site no./Names Location Principal references

sent anomalies present features T., R.

D LOW-SULFIDE GOLD-QUARTZ VEINS (MAP A)—CONTINUED

Ag Au, Zn None noted G23/Townsend and Holland T8S, R1W Moffit (1935)Ag Ag, As, Au, Cu None noted None noted T7S, R3W This reportAg Ag, Au, Cu, Fe, None noted None noted T6S, R2E Goldfarb and others (1995)

 Mn, Pb, W, Zn.

Ag Ag, Au, Cr, Fe, None noted None noted T8S, R7E Goldfarb and others (1995)

 Mo, W.

Ag Ag, Au, Ba, Co, None noted G8/Kimball Pass T4S, R2E U.S. Bureau of Mines (1980), Goldfarb and

 Cr, Cu, Zn. others (1995).

G9/Kimball Pass East T4S, R2E U.S. Bureau of Mines (1980), Goldfarb and

 others (1995).

G10 T4S, R2E U.S. Bureau of Mines (1980), Goldfarb and

 others (1995).

G11 T4S, R2E U.S. Bureau of Mines (1980), Goldfarb and

 others (1995).

Ag None noted None noted G24/Worthington Glacier T8S, R3W U.S. Bureau of Mines (1980)

G25 T8S, R3E U.S. Bureau of Mines (1980)

None noted None noted None noted Goldfarb and others (1995)

Ag, As, Au, Cu, None noted G6/Opal, Tiger Mining Co. T4S, R4E MacKevett and Holloway (1977)

Pb, Zn. G7/Fivemile Creek T1S, R5E Berg and Cobb (1967)

Au, W None noted None noted T4S, R1W Goldfarb and others (1995)Au, B, Co, Cr, Ni None noted None noted T2S, R8W Goldfarb and others (1995)Ag, As, Au, Cu None noted G57/Columbia Glacier West T9S, R10W U.S. Bureau of Mines (1980)

G58/Columbia Glacier East T9S, R10W U.S. Bure au of Mines (1980)

Ag, As, Au, Cu, None noted G4/Loraine Creek T3S, R7E U.S. Bureau of Mines (1980)

Fe. G5/Benito Creek T3S, R7E Moffit and Mertie (1923)

Cu None noted G3/Copper Creek T2S, R7E U.S. Bureau of Mines (1980)

Ba, Cu, Fe None noted G2/Chetaslina Ri ver T2N, R5E U.S. Bureau of Mines (1980)

None noted None noted G1/Kaina Lake T1N, R6W U.S. Bureau of Mines (1980)
drainages favorable for Table 2. Characteristics of tracts favorable for low-sulfide gold-quartz veins and drainages favorable for

ONTINUED precious-metal placers in the Valdez 1° 

x 3° quadrangle, Alaska—CONTINUED

mmodities Geochemical Geophysical Site no./Names Location Principal references

sent anomalies present features T., R.

PRECIOUS-METAL PLACERS (MAP A)—CONTINUED

Ag, As, Au, Co, Mineral Creek T8S, R6W Jansons and others (1984), Goldfarb and Cu, Pb, Zn. others (1995).Ag, As, B, Pb Salmon Creek T9S, R7W Jansons and others (1984), Goldfarb and

 others (1995).

As, Co, Cr, Cu, Ni Solomon Gulch T9S, R6W Jansons and others (1984), Goldfarb and

 others (1995).

Ag, As, Au, Ba, Bi, Browns Creek T20S, R4W Jansons and others (1984), Goldfarb and Co, Cu, Mn, Pb. others (1995).Ag, As, Bi, Co, Bench Creek T9S, R3W Jansons and others (1984), Goldfarb a nd Cu, Mn, Pb. others (1995).Ag, As, Au, Co, Marshall Glacier T9S, R2W Jansons and others (1984), Goldfarb and Cu, Mn, Pb. others (1995).Ag, As, Au, B, Tasnuna River T10S, R3E Jansons an d others (1984), Goldfarb and Bi, Co, Cu, Mn, others (1995). Pb, Sb.Ag, As, Au, B, Cleave Creek T9S, R2E Moffit (1914), Jansons and others (1984), Bi, Co, Cu, Mn, Golfarb and others (1995). Pb, W, Zn.Ag, Au, Cu, Pb Little Bremner River T8S, R5E Moffit (1914), Jansons and others (1984),

 Goldfarb and others (1995).
eposits Table 3. Characteristics of tracts favorable for massive sulfide deposits

in the Valdez 1° x 3° quadrangle, Alaska—CONTINUED

esence of mafic

copper (±iron-zinc)

 northwest-trending

mmodities Geochemical Geophysical Site no./Names Location Principal references

sent anomalies present features T., R.

VOLCANOGENIC DEPOSITS (MAP B)—CONTINUED

Au, Ag, Ag, As, Au, B, Bi, Positive C3/Midas, All American T10S, R6W Johnson (1915), Moffit and Fellows (1950),

Co, Cr, Cu, Fe, aeromagnetic Rose (1965), Crowe and others (1992).

Mn, Ni, W. highs located C4A, B/Addison-Powell, Sulphide T10S, R5W Johnson (1916), Moffit and Fellows (1950),

 over mafic Gulch. Rose (1965). igneous rocks.

Zn Ag, As, Cr, Cu, Ditto C1/Jack Bay (1) T9S, R8W Johnson (1919b), Moffit and Fellows (1950)

Fe, Pb, Zn. C2/Jack Bay (2) T9S, R8W Johnson (1919b), Moffit and Fellows (1950)

Ag, As, Co, Cr, Cu, Ditto C5/Wortmanns Glacier T10S, R3W Winkler and others (1981a), Goldfarb and

Fe, Pb, W, Zn. others (1995).

Ag, As, Cu, Fe, Pb, None noted C6/Tsina Glacier T7S, R3W Winkler and others (1981a) Zn.Ag, As, Au, Cr, Cu, None noted None noted T8S, R1E Goldfarb and others (1995) Fe, Mn, Pb, W, Zn.

As, Au, Cu, Mn None noted None noted T8S, R4E Goldfarb and others (1995)

Ag, Co, Cu, Fe, None noted None noted T9S, R7E Goldfarb and others (1995)

 Mn, Pb, Zn.Ag, B, Co, Cu None noted C7/Falls Creek T6S, R6E Moffit (1914), Goldfarb and others (1995)

C8/Divide Creek T6S, R6E Moffit (1914)C9/Surprise Creek T5S, R6E Moffit (1914)C10/Blackney T5S, R6E Moffit (1914), Goldfarb and others (1995)

B, Cu, V, Zn None noted C12/Copper Queen, Copper King, T3S, R8E Moffit and Mertie (1923)

 Mineral King, Swayze.C13/Curtis, Goodyear, Elizabeth, Henry T2S, R7E Moffit (1915), Moffit and Mertie (1923) Prather, Lizzie G., Louise, Marie Antoinette, Mary Ellen, Marmot.C14/Lawton, Leland, Albert Johnson, T2S, R7E Mendenhall (1905), Moffit and Mertie (1923) Guthrie, Cliff, Fog, Elliott Creek.C15/Chance T2S, R7E Moffit and Mertie (1923)C16/Blue Bird, Bunker Hill, T2S, R8E Moffit and Mertie (1923), Van Alstine and Forget-Me-Not, Montana Boy. Black (1946).C17/Mullen, Cave, Mountain Sheep, T2S, R7E Moffit and Mertie (1923), Van Alstine and Peacock. Black (1946).

None noted None noted C11/Iron Creek T3S, R7E U.S. Bureau of Mines (1980)

None noted None noted None noted T1S, R7E This report

Cu, Fe None noted C18/Cheshnina River T1N, R6E U.S. Bureau of Mines (1980)

Cu, Fe, Zn None noted C19/Willow Mountain T1S, R1E Berg and Cobb (1967), MacKevett and

 Holloway (1977).

Ag, As, Ba, Zn None noted C20/Heavenly Ridge T1N, R9W Winkler and others (1981a), Newberry (1986)
eposits Table 3. Characteristics of tracts favorable for massive sulfide deposits

in the Valdez 1° x 3° quadrangle, Alaska—CONTINUED

mmodities Geochemical Geophysical Site no./Names Location Principal references

sent anomalies present features T., R.

KENNECOTT-TYPE DEPOSITS (MAP B)—CONTINUED

Au, B, Cu, V, Zn None noted C12/Swayze T3S, R8E Moffit and Mertie (1923), Van Alstine and Black

 (1946).

C16/Ammann T2S, R8E Moffit and Mertie (1923), Van Alstine and Black

 (1946).

C17/Mullen, Cave T2S, R7E Moffit and Mertie (1923), Van Alstine and Black

 (1946).

e noted None noted None noted None noted T1S, R7E This reporte noted None noted None noted None noted T1N, R6E This report
osits Table 4. Characteristics of tracts favorable for magmatic deposits

in the Valdez 1° x 3° quadrangle, Alaska—CONTINUED

esence of ultramafic

e of mines or prospects;

mmodities Geochemical Geophysical Site no./Names Location Principal references

sent anomalies present features T., R.

B) LAYERED AND PODIFORM CHROMITE DEPOSITS (MAP B)—CONTINUED

platinum- Co, Cr, Cu, Fe, Pronounced M1/Dust Mountain T3S, R3E Foley and Barker (1985) , Newberry (1986)

up Ni, Pd, Pt. positive M2/Sheep Hill T3S, R2E Foley and Barker (1985), Newberry (1986)

ments). aeromagnetic M3/Bernard Mountain T3S, R1E Hoffman (1974), Foley and Barker (1985),

 anomalies. Newberry (1986).

Cr, Cu, Ni, V Ditto None noted T3S, R4E Goldfarb and others (1995)

Co, Cr, Cu, Fe, Ditto M4/Barnette Creek T1S, R9W Winkler and others (1981a), Newberry (1986)

 Ni, V.

NICKEL-COPPER SULFIDE DEPOSITS (MAP B)—CONTINUED

Cu (Co, Ag, Ag, As, Au, B, Local, high- N1/Summit Lake T7S, R6E MacKevett and Holloway (1977), U.S. Bureau

tinum- Co, Cr, Cu, amplitude of Mines (1980 ).

up Fe, Ni, Pb, positive aero- N2/Spirit Mountain T6S, R6E Kingston and Miller (1945), Herreid (1970)

ments). Pd, Pt, Zn. magnetic N3/Summit Lake T6S, R6E MacKevett and Holloway (1977)

 anomalies. N4/Summit Lake T6S, R7E U.S. Bureau of Mines (1980)

N5/Summit Lake T6S, R7E" U.S. Bureau of Mines (1980)

 Cu? Ag, B, Co, Cr, Cu, Pronounced None noted T3S, R8W Goldfarb and others (1995)

Fe, Mg, Ni, V. positive

 aeromagnetic

anomaly.

Cu Co, Cr, Cu, Fe, Ditto None noted T3S, R3E Newberry (1986), Goldfarb and others (1995)

tinum- Mg, Ni, Pd, Pt.

up

ments.

Cu Ag, Au, Co, Cr, Ditto None noted T1S, R9W Newberry (1986), Goldfarb and others (1995)

Cu, Fe, Mg, Ni, V.
ermissive for porphyry Table 5. Characteristics of tracts favorable for polymetallic vein deposits and permissive for porphyry

Alaska copper-molybdenum deposits in the Valdez 1° 

x 3° quadrangle, Alaska—CONTINUED

esence of quartz

ssive geochemical

mmodities Geochemical Geophysical Site no./Names Location Principal references

sent anomalies present features T., R.

POLYMETALLIC VEINS (MAP A)—CONTINUED

data Ag, As, Au, Cu, None noted None noted T4S, R3W Goldfarb and others (1995)

Fe, Mo, Pb, W,

 Zn.

data Ditto Ditto None noted T5S, R5W Goldfarb and others (1995)

data Ag, Co, Cr, Cu, Ditto None noted T3S, R6W Goldfarb and others (1995)

 Mg, Sb, Ti, Zn.

(MAP B) PORPHYRY COPPER-MOLYBDENUM STOCKWORKS AND VEINS (MAP B)—CONTINUED

Mo Cu, Mo None noted None noted T4S, R6E MacKevett and Holloway (1977)

data Co, Mo, V Ditto None noted T1N, R6W Goldfarb and others (1995 )