GEOLOGICAL SURVEY CIRCULAR 617 

Results of Geological and 

Geochemical Investigations 

in an Area Northwest of 

the Chulitna River 

Central Alaska Range 

Results of Geological and 

Geochemical Investigations 

in an Area Northwest of 

the Chulitna River 

Central Alaska Range 

By C. C. Hawley, Allen L. Clark, M. A. Herd rick, 

and Sandra H. B. Clark 

GEOLOGICAL SURVEY CIRCULAR 617 

Washington 1969 
United States Department of the Interior 

WALTER J. HICKEL, Secretary 

Geological Survey 

William T. Pecora, Director 

Free on application to the U.S. Geological Survey, Washington, D.C. 20242 
Abstract---------------------------------

Introduction------------------------------

Geologic setting ----- --- - - - - ------ - - - --- - -

Geologic studies of mineral deposits and 

occurrences-----------------------------

Syngenetic occurrences in serpentinite -- --

Epigenetic deposits and occurrences ------

Mineralized areas in southwestern 

half of area -------------------------

Partin Creek occurrence -------------

Canyon Creek occurrence and 

Ready Cash prospect----------------

Ohio Creek tin-bearing greisen--------

Mineralized areas in northeastern 

half of area --------------------------

CONTENTS 

Page 

1 

1 

1 

3 

3 

8 

8 

8 

8 

8 

9 

Geologic studies of mineral depoE-\its and 

occurrences--Continued 

Mineralized areas in northeastern 

half of area- -Continued 

Costello Creek occurrence -------------

Camp Creek occurrences --------------

Lookout Mountain occurrence-----------

Long Creek prospect------------------

Geochemical anomalies in stream sedimentsAnomalies related to known deposits or 

occurrences---------------------------

Anomalies of unknown origin -------------

Summary and recommendations for 

prospecting-----------------------------

Selected references-----------------------

ILLUSTRATIONS 

Figure 1. Generalized geologic map showing the location of mineral deposits and occurrences 

in the Upper Chulitna district and an area northwest of the Chulitna River, 

Page 

9 

9 

9 

11 

12 

13 

13 

16 

19 

Page 

central Alaska Range ------------------------------------------------------------ 2 

2. Map of serpentinite belt showing concentration of nickel and chromium in streamsediment samples and location of bedrock samples---------------------------------- 7 

3. Maps of the Partin Creek area showing reconnaissance geology, sample localities, 

and concentration of copper and gold----------------------------------------------- 10 

4-6. Geologic map of4. The Canyon Creek area showing sample locations-------------------------------- 12 

5. The northeastern part of the Golden Zone-Silver King mineralized area showing 

sample locations ----------------------------------------------------------- - 14 

6. The Lookout Mountain area---------------------------------------------------- 16 

7. Map of Long Creek prospect showing sample locations-------------------------------- 17 

8. Map showing elements present in anomalous concentration in stream-sediment 

samples------------------------------------------------------------------------ 18 

TABLES 

Page 

Table 1-5. Analyses of1. Serpentinite and associated rocks----------------------------------------------- 4 

2. Samples from the Partin Creek area-------------------------------------------- 9 

3. Samples from the Canyon Creek area------------------------------------------- 11 

4. Samples from the Ohio Creek occurrence---------------------------------------- 13 

5. Samples from occurrences in the Golden Zone-Silver King mineralized area -------- 15 

6. Maximum element concentrations in stream-sediment samples below known deposits 

and occurrences----------------------------------------------------------------- 16 

III 

Results of Geological and Geochemical Investigations 

in an Area Northwest of the Chulitna River 

Central Alaska Range 

By C. C. Hawley, Allen L. Clark, M. A. Herd rick, 

and Sandra H. B. Clark 

Abstract 

Sedimentary and volcanic rock units of Paleozoic and Mesozoic 

age, faults, and elongate bodies of intrusive rock, particularly 

serpentinites, have a dominant northeasterly trend in an area 

northwest of the Chulitna River between Eldridge Glacier and Bull 

River. The serpentinites 1 o c a 11 y contain abnormal (as much as 

0.5 percent) concentrations of nickel, have one newly identified 

occurrence of chromite, and are hosts to small epigenetic lodes 

containing copper, gold, and silver. Other epigenetic concentrations 

of copper or other metals occur in interlayered basalt and limestone at Partin and Canyon Creeks in the southwestern part of the 

area and in porphyry near Costello Creek in the northern part of 

the area. Tin occurs in greisen on upper Ohio Creek, and abnormal 

concentrations of tin also characterize mineralized rocks along 

Canyon Creek and at a prospect near Long Creek. Mineralized 

rocks characterized by silver, lead, and zinc crop out near Lookout Mountain. 

Anomalous concentrations of gold and other metals occur in 

stream sediments at isolated sites in upper Long Creek and at 

Coal Creek, as well as in several areas near known lode mineral 

occurrences. Shotgun and McCallie Creeks both contain stream 

sediments with anomalous concentrations of metals and both head 

into the basalt-limestone unit which is the host rock at Partin and 

Canyon Creeks; these facts suggest that other concentrations may 

be found. 

INTRODUCTION 

A mineralized area near the West Fork of the 

Chulitna River has been known since the early 1900's 

(Capps, 1919; Ross, 1933). The area, called the Upper 

Chulitna district (fig. 1 ), includes the Golden Zone 

mine and Silver King and Copper King prospects which 

were ihvestigated by the U.S. Geological Survey in 1967 

(Hawley and Clark, 1968). 

The aim of the investigations in 1968 was to extend 

geologic mapping and geochemical sampling to areas 

adjacent to the Upper Chulitna district; this report 

summarizes geologic findings and emphasizes results 

that may have economic significance. The main con1 

tributions are the recognition of rocks containing unusual concentrations of copper, silver, tin, and other 

metals at several places and the identification of a 

belt containing bodies of alpine-type serpentinite. The 

main copper-bearing localities are near Partin, Canyon, and Costello Creeks; silver is characteristic of 

rocks near Lookout Mountain; tin is found in greisen 

in upper Ohio Creek and with arsenopyrite at Canyon 

Creek. 

The report also summarizes the results of streamsediment sampling; the data are supplemented by a 

series of geochemical maps in a U.S. Geological Survey open-file report (Hawley and Clark, 1969). 

GEOLOGIC SETTING 

The Upper Chulitna district and ad joining areas have 

a strong northeasterly structural grain shown by the 

orientation of rock 1 ayers, folds, and faults, and by 

the elongation of intrusive bodies of igneous rock (fig. 

1 ). 

Layered rocks of Paleozoic and Mesozoic age predominate, but coal-bearing rocks of Tertiary age crop 

out in the Costello Creek coal fields in the northeastern 

part of the mapped are a (fig. 1). The pre-Tertiary 

layered rocks can be divided into four main units. The 

oldest rocks, principally siliceous argillite and interlayered graywacke-argillite, crop out in the southeastern part of the area. They are over 1 a in with 

angular unconformity by a sequence of red beds and 

limestones that grade upward into argillite. The red 

beds contain much volcanic materia 1. Ross ( 1933, 

p. 298 and 300) assigned the red beds to the Carboniferous, probably Permian, and the limestones to the 

Upper Triassic. In some areas a unit of basalt, subordinate mafic intrusive rock, and bedded chert lies 
Base fro m U.S. Geological Survey 

\,250,000, Healy, 1956 0 2 4 MILES 

Figure 1.--Generalized geologic map showing the location of mineral deposits and occurrences 

in the Upper Chulitna district and an area northwest of the Chulitna River, central Alaska 

Range. 

2 
EXPLANATION 

Sandston e, co nglomerate. coal, and unconsolidated 

deposits 

): 

G ranite. quartz monzonite. quartz porphyry, and aplite ~ 

Quartz diorite. diorite, and garnetiferous porphyry 

Serpentinite Gabbro and basalt 

D ark argillite, graywac

-ke. and co nglom erate 

D + 

+ 

Interl ayered limestone and basalt 

Red beds, limestone, and limy argillite 

Basalt and bedded chert 

Locally includes intrusive mafic rocks 

Siliceous argillite and 

-interlayered graywacke argillite 

Contac t 

Includes approximate and inferred contacts 

Fault 

Long-dashed where approximate: short-dashed 

where inferred; dotted when: concealed 

Quartz v"""""" ein 

Placer gold occurrence 

Known lode mineral dep• osit or mineral occurrence 

described in text 

I o de mineral • occurre nct· 

Figure 1.--Cont i nue d . 

i= 

0: 

w 

1-

u 

0 

N 

0 

{/) 

w 

::;: 

u 

0 

N 

0 

w 

_J 

.. 

Q_ 

between the argillite-graywacke unit and the red beds. 

Overlying the argillite in the red-bed and limestone 

unit is a distinctive unit of interlayered limestone and 

basalt which apparently thickens southward. The 

uppermost unit is composed of dark-colored detrital 

rocks-argillite, graywacke, and conglomerate. A 

pelecypod, Buahia sub ~ae s (Imlay, not Keyser ling), 

collected from the dark -colored detrital sequence near 

upper Costello Creek is of Early Cretaceous age 

(David L. Jones, written commun., 1968). 

The layered sedimentary and volcanic rocks are 

highly folded and faulted. The folds (not shown in fig. 

3 

l) are asymmetric anticlines and synclines with 

northwest-dipping axial planes. Fold axes generally 

plunge northeastward. 

The sedimentary and volcanic rocks of the area are 

cut by igneous bodies which are ultramafic to granitic 

in composition. Serpentinite and gabbro are found in a 

belt along the southeast flank of the area. Granite and 

porphyry of intermediate composition occur in stocks 

and numerous bodies too small to show, particularly 

in the northern part of the area. The igneous rocks 

were emplaced after folding and some faulting, but 

before the deposition of the coal-bearing beds of Tertiary age. 

Faults, including a complex zone called the Upper 

Chulitna fault (fig. 1), also trend northeasterly; most 

are high angle. The Upper Chulitna fault and subsidiary 

subparallel faults controlled the emplace m en t of 

masses of serpentinite and fine-grained gabbro. A 

second major fault separates the red-bed, limestone, 

and ar gillite unit from the interlayered basalt and 

limestone in the southwest part of the area. 

GEOLOGIC STUDIES OF MINERAL DEPOSITS 

AND OCCURRENCES 

The mineral deposits or occurrences of the area 

comprise syngenetic or nearly syngenetic bodies of 

chromite and nickel-bearing minerals and epigenetic 

bodies containing copper, arsenic, gold, and other 

metals. Chr omium and nickel occur in serpentinized 

ultramafic rocks; epigenetic bodies occur in several 

host rocks. 

The epigenetic deposits and occurrences are distributed widely but are more numerous and larger in 

the area north of Long Creek (fig.1). That area contains the known deposit at the Golden Zone mine and 

the prospects at Silver King and Copper King. Other 

occurrences include the Long Creek prospect and the 

ones at Costello C r e e k and Lookout Mountain (fig. 1 ). 

Another zone where epigenetic occurrences seem to 

be relatively numerous extends northeastward from 

south of Partin Creek to Canyon Creek in the southwest part of the area. 

SYNGENETIC OCCURRENCES IN SERPENTINITE 

A discontinuous belt of alpine-type serpentinite 

bodies can be traced about 25 miles northeastward 

from Eldridge Glacier to just south of the Dunkle coal 

mine (figs. 1 and 2). Individual bodies are as much 

as 1,000 feet thick and can be traced for more than 

4 miles; the largest masses are in the Upper Chulitna 

fault zone. The serpentinite is interesting economically 

because locally it contains anomalous amounts of 

nickel, chromium, copper, and gold (table l ). 

The serpentinite bodies include dark-green to black 

massive serpentinite, sheared serpentinite and soapstone, and pale- to dark-greenish-brownquartzcarbonate rock formed by alteration of serpentinite. 

Most serpentinite samples contain 1,000-3,000 ppm 
Table 1.--An~lyses of serpen-

[Analysts: Joe Curry, R. L. Miller, Buryl Wescott, Richard Tripp, Harriet Neiman, C. L. Forn. 

Riley, W. D. Goss, and Joseph Haffty. Determination of Fe and Cr on sample 10 by Claude 

given in percent. Analyses, unless noted, are semiquantitative spectrographic and are reing symbols: N, not detected; L, detected but beiow limit of determination; ---, not looked 

tion, limit of determination shown in parentheses: Be (1), Bi (lO), Cd (20), La (20), Sb 

14 (ACL035) and 100 ppm in 18 (AGJ602); Cd, 300 ppm in 18 (AGJ602); La, 20 ppm in 1 (AGJ878) 

shown in figure 2] 

Sample 

No. 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

Lab. 

No. 

AGJ876 

877 

878 

879 

880 

835 

837 

846 

847 

848 

843 

844 

830 

831 

832 

840 

841 

842 

874 

875 

ACL536 

901 

902 

903 

904 

905 

906 

AGJ210 

801 

803 

ACL035 

037 

036 

ACF063 

ACE614 

AGJ615 

616 

601 

604 

602 

Field 

No. 

Sll-H6A 

H6B 

H6C 

H6D 

H6E 

ACK293 

294 

299 

301 

304 

ACS811 

818 

CK279 

279A 

282 

ACS801 

802 

803 

S6-H50A 

B 

M824 

ACK207A 

207B 

207C 

207E 

207F 

207G 

ACK210 

201 

205 

67HX26 3 

HX329A 

HX327 

67AHX177 

67HX227 

SK40 

SK40B 

SK-7 

SK-11 

SK-8 

Ag 

N 

N 

15 

1 

N 

N 

N 

N 

N 

N 

N 

L 

N 

N 

N 

N 

N 

N 

N 

N 

N 

N 

N 

N 

N 

L 

N 

N 

N 

N 

N 

N 

N 

N 

N 

• 7 

• 7 

• 7 

• 7 

500 

Limits of determination----- 0.5 

As 

N 

N 

N 

L 

N 

N 

N 

N 

N 

N 

N 

N 

N 

L 

N 

N 

N 

N 

N 

N 

N 

N 

N 

N 

N 

N 

N 

N 

N 

N 

300 

N 

N 

N 

N 

N 

N 

L 

300 

>10,000 

Au 1 B 

N 

N 

.1 

.04 

.02 

L 

30 

30 

30 

N 

Ba Co 

70 50 

N 70 

100 200 

100 150 

50 5 

N 50 70 150 

.02 L 50 70 

N L 1,500 50 

N L L 50 

N 30 L 150 

Cr 

500 

2,000 

20 

150 

10 

1,500 

1,500 

1,000 

2,000 

2,000 

N N L 

N L 150 

.06 10 70 

.04 L 1,000 

.04 20 50 

50 3,000 

N N 

N 200 

N L 

N 50 

N 20 

20 

N L 

N 150 

N 70 

N 70 

N 

N 

.06 

• 3 

.02 

N 

N 

.02 

N 

N 

15 

10 

20 

20 

L 

10 

70 

50 

30 

20 

N 500 

N 150 

N 300 

.02 200 

6.6 30 

7 30 

50 1,500 

70 1,500 

N 300 

L 70 

L 500 

L 150 

N 200 

50 70 

100 100 

300 50 

N 150 

N 150 

N 150 

N 100 

N 30 

70 70 

70 150 

L 70 

20 50 

5 150 

30 5 

N 100 

N 100 

N 200 

N 200 

N 100 

N 150 

70 L 

3,000 

>5,ooo 

3,000 

>5,ooo 

5,000 

3

27 

1,500 

2,000 

2,000 

2,000 

150 

150 

2,000 

1,500 

1,500 

1,500 

3,000 

150 

2,000 

5,000 

3,000 

5,000 

2,000 

1,500 

15 

200 0.02 10 5 5 5 

1 Atomic absorption. 2 Specific instrumental or chemical method. 3 Given in percent. 

4 

Cu Hg 2 Mo Mn 

1 750 

20 1

75,000 

1

20' 000 

1120 

L 

10 

150 

7 

15 

7 

7 

200 

70 

7,000 

70 

5 

7 

20 --- i 

50 

2 

70 

10 

7 

15 

L 

7 

L 

3,000 

10 

100 

20 

30 

5 

L 

20 

50 

100 

30 

2,000 

0.03 

.01 

.06 

.08 

2.0 

N 1,000 

N 500 

15 15 

L 300 

L 15 

L 700 

L 700 

N 1,500 

N 2,000 

N 700 

N 1,500 

N l,QOO 

5 1,500 

L 2,000 

7 3,000 

N 700 

N 1,000 

N 1,000 

L 700 

N 700 

N 2,000 

N 300 

N 300 

N 300 

N 300 

5 2,000 

N 1,000 

L 700 

10 500 

N 700 

N 1,000 

N 700 

N 1,000 

N 700 

L 1,500 

N 700 

N 3,000 

N 700 

N 500 

N 15 

Nb 

L 

L 

L 

L 

L 

L 

L 

L 

L 

L 

L 

L 

L 

L 

L 

L 

L 

L 

L 

L 

N 

L 

L 

L 

L 

10 

L 

L 

L 

L 

L 

L 

N 

N 

30 

L 

L 

L 

L 

10 

5 0.01 5 10 10 
tinite and associated rocks 

Fire assay and quantitative spectrographic analyses for platinum-group metals by L. B. 

Huffman, Jr. Results are given in parts per million except Fe, Mg, Ca, and Ti, which are 

ported in the series 0.1, 0.15, 0.2, 0.3, 0.5, 0.7, 1.0, 1,5, and so on, or by the followfor; H, interference. Looked for but not detected or detected but below limit of deter~ina-

(100), Sn (10), and W (50). Exceptions are (lab numbers in parentheses): Bi, 10 ppm in sample 

and 1 (AGJ879); Sb, 3000 ppm in 18 (AGJ602); and Sn, 10 ppm in 7 (AGJ832). Sample numb~rs are 

Ni Pb Pd 2 Pt 2 Rh 2 Sc Sr v y Zn Zr Fe Mg Ca Ti 

150 L 30 200 150 20 200 30 7 3 5 0.2 

1,500 L 15 N 30 L L N 7 10 L .03 

50 10 5 N 70 L 200 L 20 • 3 L .05 

70 L 20 N 200 15 200 20 20 2 .05 . 2 

L 15 5 N 15 10 L 20 3 . 05 N . 2 

2,000 N <o.oo4 <0.01 <o.oo5 5 N 30 L N L 7 10 L .01 

1,500 10 <.004 <.01 <.oo5 7 70 30 L N L 5 10 3 .005 

150 L 70 150 300 10 N 30 10 7 7 • 7 

1,500 L 5 300 30 L L L 5 7 7 .03 

3,000 L 7 L 30 L L L 10 >10 . 3 H 

1,500 L 7 300 30 N N L 7 7 3 L 

30 L 7 N 70 N N 50 10 . 7 .05 .15 

700 L .005 <.01 <.oo5 15 70 150 15 L 50 7 7 5 . 5 

1,000 L <.004 <.ol <.oo5 10 150 70 10 L 20 7 7 10 .15 

100 L 20 N 200 15 L 30 15 7 .07 . 3 

1,500 L 5 N N N N L 7 7 1 .007 

2,000 L L N 20 N L L 15 10 .15 .002 

1,500 L 15 N 30 N N L N 10 . 7 .005 

5,000 N 10 N 50 N L N 10 >10 L .007 

1,500 L 10 L 70 10 L 30 7 5 1 .15 

1,000 N <.004 <.01 .019 7 10 700 N N N lg,l >10 0.7 0.07 

150 N 30 200 150 L N 30 3 3 . 3 .15 

1,500 N 7 N 20 N N N 3 7 L .003 

1,500 N 5 N 15 N N N 3 10 L .005 

1,500 N L N 15 N N N 3 7 L .003 

100 L 30 1,500 300 30 N 70 10 2 2 . 3 

200 N L N 15 N N N 2 L L .007 

1,000 N 5 150 10 N N N 3 3 >20 L 

1,500 N <.004 <.01 <.005 7 70 15 N 200 N 20 7 • 7 .005 

1,500 N .004 <.01 <.005 5 300 10 N N N 3 7 5 L 

1,500 L 5 N L N N N 7 7 . 5 .01 

2,000 N 10 N L N N N 10 >10 .07 <.001 

50 L 5 150 30 N N L 1.5 10 20 .1 

1,000 N 10 N 15 N N N 5 7 . 7 .007 

1,500 L 5 N 15 N N N 10 7 . 5 .003 

5,000 N 5 L 15 N L N 15 -10 3 L 

5,000 N 5 L 15 N L N 10 > 10 5 L 

5,000 L 7 100 50 N N N 7 10 5 .015 

5,000 10 7 N 10 N N N 15 >10 L L 

10 7,000 L N 20 L 10,000 N 10 L L .03 

5 10 0.004 0.01 o:oo5 5 50 10 10 200 20 0.05 0.02 0.05 0.001 

5 
Description of samples given in table 1 

Sample No. 

sho1J1n in 

fig. 2 Lab. No. Description 

1----------AGJ876----- Malachite-stained s e rp en tin it e; 

staining confined to fracture surfaces. 

877----- -Blocky massivegr een i sh-b la'Ck 

serpentinite. 

878------Pyrite-rich and chalcopyrite-rich 

(more than 50 percent) rock; 

quartz matrix. 

879------Pyrite-rich (more than 50 percent) 

rock. 

880------Vuggy quartz. 

2----------AGJ835------Serpentinite. 

837------Quartz-carbonate rock. Pyrite locally abundant. 

3----------AGJ846----- -Serpentinized basalt cut by jasperoid veinlets. 

84 7------Altered ultramafic rock, chiefly 

quartz-carbonate rock; vuggy. 

4-------- --AGJ848----- -Highly sheared serpentinite. 

5----------AGJ843---- --Limonite-stained quartz-carbonate 

rock which forms a 75-foot-wide 

zone between serpentinite and 

basalt. 

6----------AGJ844------20- to 30-foot-wide serpentinite 

with local q u a r t z -c a r bon a t e 

zones. 

7----------AGJ830--- ---Dark-green sheared serpentinite. 

831------Serpentinite in fault zone. 

832------Malachite-stained sheared basalt 

adjacent to serpentinite. 

8----------AGJ801------S-foot-wide zone of quartz-carbonate rock between basalt and serpentinite. 

802----- -Serpentinite with well-developed 

antigorite(?) films in veinlets and 

on fracture surfaces. 

803------Limonite-stained quartz-carbonate 

zone about 20 feet wide in serpentinite. 

9----------AGJ874- -----Greenish-black massive serpentinite. 

875------Pale-brown quartz-carbonate rock. 

Disseminated pyrite. 

10--------- ACL536----- -Massive chromite. 

ll----------ACL901------Altered quartz monzonite; forms 

the south border of serpentinite 

mass. Unit about 7 feet wide. 

(parts per million) of both nickel and chromium (table 

1) or approximately their normal amounts in ultramafic rocks (Turekian and Wedepohl, 1961). Locally, 

however, the samples contain as much as 5,000 ppm 

(0.5 percent) nickel and more than 5,000 ppm chromium. The rocks highest in nickel were found at localities 9, 17, and 18 in figure 2; the rocks highest in 

chromium, at localities 10 (massive chromite), 8, 9, 

16, and 17. 

The. coppe.r content of serpentinite is generally low, 

but epigenetic copper occurrences in serpentinite near 

Eldridge Glacier (locality 1, fig. 2) contain as much as 

7.5 percent copper. The serpentinite at locality 1 is 

cut by irregular and veinlike zones of massive pyrite 

6 

Sample No. 

sho1J1n in 

fig. 2 Lab. No. Description 

11--------- ACL902- -----Quartz-carbonate-rich serpentinite, locally massive quartz-carbonate material. Zone 3 feet wide, 

adjacent to ACL90l. 

903------Dense black serp~ntinitecutbythin 

veinlets of sheared antigorite(?). 

Zone approximately lOOfeet wide. 

Adjacent to ACL902. 

904---- --Serpentinite. 

905------Sheared and alt~red basalt. Zone 

about 25 feet wide. Adjacent to 

ACL904. 

906------Sheared fibrous material (antigorite(?)) from b~ack serpenitinite 

(ACL903). 

AGJ210------Jasperoid-calcite rock from small 

plug in basalt. Basalt is adjacent 

to serpentinite. 

12----------AGJ801------Sheared black se:--pentinite, locally 

contains incl ·sions of jade(?). 

Disseminated r"rite, locally as 

much as 20 pen:ent. 

13----------AGJ803------Strongly sheared and silicified serpentinite. 

14--------- ACL035------Sheared serpentirrte. 

037------Strongly shearec\ greenish-black 

serpentinite in a fault zone. 

038------Pale-gray bleachAd brecciated basalt. 

15--------- ACF063------Brownish-whit~ altered serpentinite. 

16--------- ACE614------Dark-grey serpentinized pyroxenite, locally cut by 1/16-inch 

veinlets of cross-fiber mineral. 

17----------AGJ615------Massive to sheared greenish-black 

serpentinite. 

616------Same as AGJ615. 

18----------AGJ601- -----Quartz-carbonate rock. 

604------Quartz-carbonate rock. 

602------Arsenopyrite-qua-:-tz vein (Eagle 

vein) on hangin1' wall of serpentinite body. V e i n as much as 1 

foot w ide, corr.ains 50 percent 

arsenopyrite. 

and chalcopyrite at least 3 feet across. Localities 7, 

12, and 18 also have epigenetic occurrences of copper 

or silver and gold. 

Massive chromite (locality 10, fig. 2) is associated 

with serpentinite that is locally a 1 t ere d to quartzcarbonate rock. The serpentinite body is lenticular 

and is as much as 1,000 feet across ardmore than 3 

miles long. Locally, the quartz-carbonate rock contains disseminated pyrite and is stain~d with garnierite. The c h rom it e was not- found in place, but 

massive chromite blocks as much as a foot across 

were found in talus. A sample of mate~ial estimated 

to contain more than 95percent chromitecontains 39.5 
5232-8 Ruby 

63"15' 

EXPLANATION 

Mafic and ultramafic rocks s. serpentinite 

bg. basalt and gabbro m, mafic dike rock 

Concentration of nickel, 

in parts per million 

0 ~70 

~ 100-150 

• 200-300 

® ~500 

(Concentration shown) 

Concentration of chromium shown if 

greater than 500 parts per million 

Examples 

e2000Cr 

200-300Ni; 2000Cr 

~500Cr 

100-150Ni; 500Cr 

&2 

Rock sample locality, table I 

63"00"L-~----------~~----~~~L-~~~L-----~----~~~--------------------------------~ 

150"00' 149" 30' 

Base from U.S. Geological Survey 

1:250,000, Healy, 1956 

2 0 2 4 MILES 

Figure 2.--Map of serpentinite belt showing concentration of nicKel and chromium 

in stream-sediment samples and location of bedrock samples. 

7 
percent Crz03 and has a Cr203:Fe203 ratio of 3.1:1. 

The chromite has only a trace of p 1 at i·n u m metals 

(sample 10, table 1), principally rhodium. 

EPIGENETIC DEPOSITS AND OCCURRENCES 

Epigenetic deposits and occurrences described below are characterized by arsenic, copper, and gold; 

generally subordinate but locally dominant are silver, 

antimony, lead, zinc, tin, and bismuth. 

Mineralized areas in southwestern 

half o:f area 

Extensive mineralized areas are located near Partin 

and Canyon Creeks in the southern part ofthe mapped 

area (fig. 1). The mineralized area in Partin Creek 

is probably the one discovered by Albert Partin in 

1917 and formerly covered by the Combination and 

Caribou claims (F. L. Thurmond, unpub. data, 1918). 

The mineralized area on Canyon Creek includes the 

Ready Cash prospect (Capps, 1919, p. 228-229; Ross, 

1933, p. 318-320) and extends for at least a mile north 

of it. 

Both mineralized areas are west of a major fault 

that is subparallel to and about 1M miles to 4 miles 

west of the Upper Chulitna fault (fig. 1); they are in 

a unit of interlayered basalt and limestone which is 

faulted against red beds, argillite, and limestone to 

the east. 

Partin Creek occurrence 

Sulfides in the Partin Creek area (fig. 3) occur in a 

zone at least 3,000 feet long and as much as 1,000 feet 

wide, elongated parallel to the local structural grain. 

Rocks within the area contain visible pyrite, arsenopyrite, pyrrhotite, and chalcopyrite. The calcareous 

rocks of the area are stained with limonite; locally, 

only a limonite gossan remains. Sulfides in the basaltic 

units are generally fresh and occur as disseminations 

and veinlets and locally, in vesicules in amygdaloidal 

basalt. Analyses of random composite sam p 1 e s of 

sulfide-bearing rock (samples A-G, I, J)andofa grab 

sample from a quartz-arsenopyrite vein (sample H) 

are given in table 2. The samples contain 20-7,000 

ppm (0. 7 percent) copper, and most contain barely 

detectable to abundant silver, gold, and arsenic. Analysis of sample K (table 2) is from copper-bearing rocks 

exposed south of Partin Creek approximately at long. 

150°00" w. (fig. 1). 

Canyon Creek occurrence and Ready 

Cash prospect 

Mineralized rocks in the Canyon Creek area occur 

in a unit of basalt and interlayered limestone with 

minor amounts of hornfelsed argillite (fig. 4 ). The area 

containing sulfides is more than a mile long and is 

elongated subparallel to a north-trending fault. A 

second fault is inferred in the valley of Canyon Creek. 

The mineralized bodies are veins of quartz, arsenopyrite, and other sulfides, and sulfides are disseminated in basalt, limestone, and hornfels. Occurrences 

8 

of mineralized rock were sampled in three parts of 

the area (fig. 4). Analyses of these samples (samples 

1-8, table 3) suggest that copper, ars~nic, tin, lead, 

zinc, silver, and minor amounts of gold are characteristic of the mineralized area. With t'le exception of 

tin, these metals or their minerals we~e reported by 

Capps (1919) and Ross (1933) at the RerdyCash prospect at the south end of the mineralized area. Tin was 

detected in all but one sample and exceE"ds 0.1 percent 

in one quartz-arsenopyrite-galena vein. 

The Ready Cash prospect was sampled and described 

by Capos (1919), Ross (1933), and F. L. Thurmond 

(unpub. data, 1918). Thurmond reported a maximum 

silver assay of 183 oz per ton (ounces rer ton) on selected galena from the prospect and a range of 5-120 

oz per ton of silver on other sulfide-ri~h samples. A 

maximum assay of about 15 oz per ton of silver was 

determined in samples collected during our brief investigation. Ross (1933, p. 318-320) believed that the 

numerous vein exposures in the vicinity of the Ready 

Cash prospect were the result of the faulting of a single 

lode, but helicopter reconnaissance sug~ests that there 

are several distinct veins. 

Sulfide mineral occurrences (sa1"'1ple localities 

9-12) are also found in precipitous te~rain about 2M 

miles northeast of the Ready Cash prospect (fig. 4). 

A possible extension of the mineralize:l area exposed 

near Canyon Creek is indicated by anomalous concentrations of copper or zinc in stream-sediment samples from nearby drainages (fig. 4). 

Ohio Creek tin-bearing greisen 

A greisen-type tin occurrence was found 3M miles 

northwest of the Canyon Creek area en upper 0 hi o 

Creek. The occurrence consists of m u s co v i t e and 

tourmaline-bearing greisen and quartz-arsenopyrite 

veins in a tourmaline-bearing granite stock. The stock 

is about a mile long and one half of a mile across 

(fig. 1). 

One traverse was made across the part ofthe stock 

east of the Ohio Creek Glacier, and gre•.sen was found 

adjacent to a biotite-rich inclusion. This inclusion is 

at least 150 feet long and is elongated approximately 

parallel to a southwesterly trending gulch. A zone of 

tourmaline greisen as much as 10 feet thick on the 

south and southeast sides of the inclusion contains as 

much as 300 ppm tin (lab. No. AGJ976, table 4). The 

tourmaline greisen grades into muscovite-bearing 

greisen that is as much as 3 feet thick and contain s 

more than 1,000 ppm tin (lab. No. AGJ975, table 4). 

Another sample of greisen collected southeast of the 

gulch also contained more than 1, 000 ppm tin (lab. No. 

AGJ977). The upper 3-10 feet of the granite near its 

contact with country rock in the northeastern part of 

the stock 1 o c a 11 y contains p e g m a t i t i c q u a r t zarsenopyrite veins, and they parallel the 50° NE. dip 

of the contact. A grab sample of one of these veins contained more than 1,000 ppm tin (lab. No. AGJ978). 
Table 2.--AnaZyses of samples from the Partin Creek area 

[Analysts: Joe Curry and R. L. ~iller. Gold analyse~ by atomi~ absorption. Other analyses are 

semiquantitative spectrograph~c and are re~orted ~n the ser~es 0.1, 0.15, 0.2, 0.3, 0.5, 

0.7, 1.0, 1.5, and so on, or by the follo~~ng ~ymbols: N, no~ d~tected; L, detected but below limit of determination. Results are g~ven ~n parts per m~ll~on except Fe and Ti, which 

are given in percent. Sample localities, except K (south of Partin Creek~ shown in figure 3] 

Sample Lab. Field Ag As Au Cu Mo Pb Sb Zn Fe Ti 

Locality No. No. 

A ACL503 68ACK344A 0.7 1,500 0.1 200 L L N L 10 0.5 

B 504 344B N 700 . 5 1,500 15 L N L 20 . 7 

c 505 344C N N N 20 L 20 N N ' . 5 

D 506 344D N N .l 300 5 L N L lf >l 

E 507 344E L N . 9 700 L L N N l(' >1 

F 508 344F N 3,000 . 7 700 7 L N L lE >l 

G 509 344G 300 N .l 20 L N N L 7 >l 

H 510 344H l >10,000 63 7,000 30 100 7,000 300 2( .015 

I 511 3441 . 5 500 

J 512 344J . 5 L 

K AGJ849 68ACK308 N N 

Limits of determination---- 0.5 200 

Samples of greisen or vein material mentioned above 

and altered country rocks also contain me as u r a b 1 e 

amounts of silver, gold, copper, lead, zinc, and tungsten (table 4). 

Stream sediment from the gulch contains abo'ut 150 

ppm tin, 200 ppm arsenic, 300 ppm copper, 7 ppm 

beryllium, 5 ppm silver, 700 ppm zinc, and a trace 

of tungsten. 

Mineralized areas in northeastern 

half of area 

Mineral deposits and occurrences are relatively numerous in the northeastern part of the area (fig. 1), 

sometimes called the Golden Zone-Silver King mineraized area. Disseminated mineral occurrences were 

identified in 1968 near Costello Creek 2).2 miles eastsoutheast of the Silver King prospect and in upper 

Camp Creek 3 miles northeast of the Silver King (fig. 

1 ). The occurrences are in porphyry and, although 

low grade, seem large enough to warrant further study 

and sampling. The dominant elements in the Costello 

Creek deposit are copper, arsenic, and gold; elements 

present in smaller amounts are silver, bismuth, and 

tin. Another disseminated mineral occurrence is near 

Lookout Mountain (fig. 1), where the mineralized 

rocks contain silver, lead, zinc, and traces of arsenic, 

gold, and tin. Apparently, neither the Lookout Mountain nor the Costello Creek occurrences have been 

prospected. An occurrence south of Long Creek has 

been partly exposed in trenches but not described previously. It is characterized by arsenic, copper, bismuth, tin, and gold. 

Costello Creek occurrence 

A fine-grained locally garnetiferous diorite porphyry contains sulfides both on fracture surfaces and 

disseminated over an area about one-fourth of a mile 

. 2 700 7 L N L lE >l 

.02 700 10 L N 200 2( >1 

. 2 1,500 L L N L 2C >l 

0.02 5 10 10 100 200 0.05 0.001 

9 

wide by three-fourths of a mile long (fig. 5}. The porphyry is part of the stock that underlies tre low hills 

northeast of Costello C r e e k (fig. 1 }. Por"Jhyry near 

samples 1A and 2A (fig. 5, table 5) is estimated to contain from 1-3 percent sulfides; arsenopyrite, pyrite, 

pyrrhotite, and chalcopyrite are visible negascopically. At sample locality 3A, the rock is brecciated 

fine-grained porphyry with minor hornfels. At sample 

localities 3A, 4A, and SA sulfides are estimated to constitute from J-2-2 percent of the rock. A sam'Jle (6A) of 

a granite porphyry dike that cuts diorite porphyry did 

not contain metals in anomalous concentration. 

Camp Creek occurrences 

Mineralized rock is exposed over approximately 

one-fourth of a mile in upper Camp Creev in sec. 5 

and near the center of sec. 9, T. 19 S., R. 10 W. (fig. 

5). Exposures are poor, but the mineralized rock is 

altered fine-grained porphyry which protruces through 

coal-bearing Tertiary rocks (fig. 5}. In sec. 9, an intrusive body is in contact with pre-Tertiar:r rocks to 

the east. 

The highest metal concentration in samples from 

Camp Creek (sample 6B, table 5) was 0.6 ppm gold, 

500 ppm copper, and 1,000 ppm zinc. Other samples 

contained appreciably less metal, but mineralization 

in all samples except sample lB was indicated by the 

presence of zinc, bismuth, and antimony. 

The occurrences in Camp Creek and mineralized 

rock north of Costello Creek suggest that mineral deposits may be buried beneath the extensive cover of 

Tertiary and Quaternary rocks at the no:-:-th end of 

the Golden Zone-Silver King mineralized area. 

Lookout Mountain occurrence 

The mineral occurrence at Lookout Moun':ain is in a 

small, locally brecciated, and poorly expos~d body of 
EXPLANATION 

Biotite-quartz ~ diorite 

B 

Limestone and siltstone 

Basalt 

Locally amygda/oidal and 

vesicular 

Limestone 

Massil'e, white to dark-gray, 

fossiliferous 

H a::: 

w 

1-

u 

0 

N 

0 

(f) 

w 

~ 

0 

z 

<( 

Base from U.S. Geological Survey 

1:63,360, Healy A-6, 1953 

Geology by A.l. Clark, 1968 G 

Limestone and siltstone, spar~e basalt 

~ 

0 

N 

0 

w 

...J 

<( 

a. 

A 

Red siltstone and conglomerate 

Contact 

Long-dashed where approximate; short-dashed 

where inferred; dotted where concealed 

Fault, approximately !orated 

Vein 

\ ~ 

\I 

Approximate boundary of mineralized 

area 

e500 Cu, 0.4 Au 

Stream-sediment locarty 

Showing metal concentration 

in parts per million 

5000 

B 

0 5000 FEET 

'9' E; 700 Cu, 0 9 Au 

Rock sample locality 

Showing metal concentration i~ parts 

per million. letter refers to table 2 

Figure 3.--Maps of the Partin Creek area. A3 Reconnaissance geologic map. B, Sample localities 

and concentration of copper and gold. 

quartz porphyry and felsite emplaced in strong 1 y 

sheared dark -gray to black argillite and quartzite. 

Scattered exposures (fig. 6) suggest that the intrusion 

is roughly circular with a diameter of 1.200 feet. 

The intrusive rock is light colored and varies from 

uniformly fine-grained felsite to quartz porphyry with 

quartz phenocrysts 2-3 mm (millimeters) in size. 

10 

Four samples of mineralized intrusive rock collected 

along the main gulch (samples 1-4. table 5) contain 

anomalous amounts of zinc. lead. and silver. and trace 

amounts of tin. A 10-foot-wide dikeofquartzporphyry 

exposed one half of a mile downstream (eample 5) contains traces of the same suite of elements. Shear-zone 

material in the main intrusive (samples 6 and 7) is 

also characterized by zinc. lead. silver. and tin. as is 
Table 3.-AnaZyses of samples fr>om the Canyon Cr>eek ar>ea 

[Analysts: Joe Curry and R. L. Miller. Analyses, unless noted, are semiquantitative spectragraphic and are reported in the series 0 .l' 0.15, 0. 2' 0. 3' 0. 5' 0. 7' 1.0, 1.5, and so on, 

or by the following symbols: N, not detected; L, detected but below limit of deterrrination. 

Results.given in parts per million except for Fe, which is given in percent] 

Sample Lab. Field 

No. No. No. 

l AGJ979 S7-9 

2 ACJ869 4 

3 865 1 

866 lB 

4 867 2 

5 868 3 

6 590 M-812 

7 591 M-814 

592 814B 

8 593 815 

9 881 S6-43 

10 883 45 

ll 884 46 

12 897 46B 

Limits of 

determination--------

1 Atomic absorption. 

Sample 

Nc. Lab. 

No. 

Sample 

type 

Ag As Au 1 Cd 

150 >10,000 0.3 300 

500 >10,000 .4 500 

7 N .4 N 

• 7 N .02 N 

3 700 .06 N 

3 500 .04 N 

3 L .02 N 

10 >10,000 0 3 N 

3 200 .02 N 

N N .04 N 

N N .1 N 

2 L • 9 N 

N N .l N 

3 700 0 8 N 

0.5 200 0.02 20 

Description 

1------AGJ979--- 2 -foot chip-----Chalcopyrite-arsenopyrite 

vein in Canyon Creek approximately 100 feet from 

portal of I ow e r R e a d y 

Cash adit. 

2----- -AGJ869-- ---Grab -------Quartz-arsenopyrite vein 

material. 

3------AGJ865---- -Chip --------Copper-stained gossan material. 

866---- -Grab -------Iron -stained hornfels. 

4------AGJ867- ----Chip --------Iron-stained argillite and 

quartz-pyrite vein material; inferred fault zone. 

5------AGJ868-----Grab -------Iron-stained basalt unitapproximately 30 feet wide. 

6------AGJ590-----50-foot ------Reddish-brown altered bachip salt. Dark-green amygdules. 

a limonite-stained sericitic breccia (sample 8). Similar breccia, which contains fragments of both intrusive 

and country rock, is exposed west of the gully. Silver 

is also present, but near the limit of detection, in the 

adjacent clastic country rocks (samples 9, 10, and 11). 

Long Cr>eek pr>ospect 

Shallow trenches and prospect pits south of Long 

C r e e k (fig. 1) expose a weakly mineralized area approximately 300 by 600 feet (fig. 7). Minor amounts of 

galena, sphalerite, pyrite, and chalcopyrite occur in 

massive quartz-arsenopyrite veins and as disseminations in the country rock. Sampling of the area (table 

5) indicates anomalous concentrations of gold, silver, 

Cu Mo Pb Sb Sn Zn Fe 

1 7,800 10 1,000 100 300 7,000 15 

3,000 7 >20,000 700 >1,000 10,000 15 

5,000 15 N N L L 10 

700 7 N N L N 7 

150 7 300 N L L 5 

300 7 15 N 10 200 10 

300 L 70 N 700 300 7 

1,000 10 100 500 150 L 15 

700 5 10 N 150 L 10 

100 N L N N N 2 1 150 5 L N N 200 20 1 4,000 15 L N N L 15 

11 

1 500 

300 

5 

Sample 

No. 

L 

5 

10 

Lab. 

No. 

L N 

300 3,000 

10 

Sample 

type 

100 

N N 7 

N 200 10 

10 200 0.05 

Descr>iption 

7------AGJ591-----Grab -------1~- to 2-foot quartz vein, 

approximately 50 percent 

sulfides, mainly arsenopyrite with minor chalcopyrite and tetrahedrite(?). 

592-----Grab -------Same as AGJ591. 

8------AGJ593-----Grab -------Dark-green to t 1ack amygdaloidal basal~. 

9-- -·- --AGJ881- ----Grab -------Contact zone t ~tween basalt and limertone. 

10------AGJ883-----Grab -------1- to In-foot vein or pod of 

quartz and sulfides. Near 

contact of dio':"ite porl'hYry and hornft>lsed argillite. 

ll------AGJ884-----Grab -------Sulfide-bearing hornfels. Less than 2 percent 

pyrrhotite, c'l.alcopyrite, 

and sphalerite. 

12------AGJ897-----Surficial ----Colluvium below AGJ884. 

arsenic, and copper, and minor amounts of molybdenum, bismuth, lead, antimony, tin, and zinc. The 

metal suite of the occurrence is typical of the area, but 

bismuth, antimony, and tin are present in larger concentrations and in more samples than in most nearby 

deposits. 

The country rocks of the mineralized area are dense 

dark-gray hornfelsed conglomerates, bre~cias, and 

shales that are cut by a small plug and dikes of quartz 

porphyry. The metamorphosed country rock contains 

1-2 percent disseminated sulfides, primarily pyrite 

and arsenopyrite with minor amounts of chalcopyrite. 

The intrusives are stained with limonite and locally 

contain abundant pyrite and arsenopyrite. 
og 

'" / ~OX ~--/ \ ,'~-~ ,./' ~00 , READY CASH, 

•• :' PROSPECT/ 500 

Base from U.S. Geological Survey 

1:63,360, Heoly A-6, 1953 

40 

_...;.-.-

EXPLANATION 

8 

Quaternary deposits, uncivided 

1<.® I 

Quartz diorite porphyry 

8 

Gabbro(?) 

Basalt and mafic 

~ 

~ 

breccia( b) and 

serpentinite( s) 

I 

}

ffi >- t-0:: 

<(<( 

::JZ 

)I 

w~ l90:: 

<(W 

u 

z 

::l 

~ 

Argillite, graywacke, and conglomerate(?) 2 

0 

U) 

w 

Basalt and limeston<c" 

Limestone and calcareous argillite 

Red siltstone, sandstone, 

and conglomerate 

b. basaltic interbed 

Argillite and graywacke 

~ 

0 

z 

<( 

~ 

0 

N 

0 

w 

..J 

<( 

a. 

0:: 

w 

a. 

a. 

::l 

0 lMILE 

Contact 

2 

• 

<200 Zinc(] D 50-70 Copper 

200 Zinc 41 t 100 Copper 

Long-dashed where approximate; short-dashed 

where inferred, dotted where concealed 

Rock Fault sample locality 

(table 3) ~ 300 Zinc ~ t> ~ 150 Copper Long-dashed where approximate; short-dashed 

Concentration Concentration shown where inferred; dotted where concealed 

shown if ~ 300 _E_O 

Example Strike and dip of beds 

® 300 = < 200 Zinc 

and 300 Copper Disseminated sulfides Stream-sediment sample locality 

Showing copper and ::inc concentration, 

in parts per million 

>--

Ad it 

Figure 4.--Geologic map of the Canyon Creek area showing sample locations. 

Most exposures in the area are in pits and trenches, 

and some of these are caved. Massive arsenopyrite 

vein material was found in place in only two pits (samples A and N, table 5), althoughmassivevein material 

was also found on four other dumps. This fact and the 

uniformity of gold content in five of the six samples 

suggests that vein material may have been moved to 

some of the pits from one or another of the vein outcrops. Although the significance of the prospect cannot, 

therefore, be assessed without further sampling, the 

country rocks are sulfidized. Vein materials contain 

gold and appreciable amounts of silver, bismuth, and 

tin, and sediment in the stream draining the prospect 

area shows 7 ppm Ag and 70 ppm Pb (Haw 1 e y and 

Clark, 1968, sample 44, table 3). 

12 

GEOCHEMICAL ANOMALIES IN STREAM SEDIMENTS 

One hundred and sixty five stream-sediment samples, including some duplicates, were collected in the 

area in 1967 and 1968. The samples were collected, . 

where possible, from active streams, ani the -80mesh 

fraction was analyzed for gold by an atorric-absorption 

method and for 30 other elements by a semiquantitative-spectrographic method. 

Of those elements, silver, gold, copper, lead, zinc, 

and arsenic occur in enough samples anc had sufficient 

range in concentration to be generally useful in determining anomalies. Medians, shown below, and limits 

of anomalous concentrations were es':imated from 
Table 4.--AnaLyses of sampLes from the Ohio Creek occurrence 

[Analysts: Joe Curry, R. L. Miller, R. Tripp, W. R. Vaughn, and E. E. Martinez. Analyses, unless noted, are semiquantitative spectrographic and are reported in the series 0.1, 0.15, 

0.2, 0.3, 0.5, 0.7, 1.0, 1.5, and so on, or by the following symbols: N, not detected; L, 

detected but below limit of determination; H, interference. Results are given in parts per 

million] 

Lab. 

No. 

Field 

No. Ag As B Be Bi Cd Cu Mo Pb Sb Sn w Zn 

AGJ973 

974 

975 

976 

977 

978 

S7-6A 3 

6B 5 

6D 30 

6F 7 

6G 70 

6I 20 

L 

N 

3,000 

L 

300 

>10,000 

0.04 

.04 

.04 

.04 

.02 

.04 

>2,000 

>2,000 

H >50 

>2,000 

30 

30 

5 

5 

3 

5 

15 

3 

L 

10 

30 

20 

N 

20 

N 

150 

50 

N 

N 

N 

10 

150 

150 

1,500 

150 

1,000 

N 

L 

N 

L 

N 

L 

30 

50 

200 

20 

30 

300 

N 15 70 

L 200 L 

L >1,000 150 

N 300 N 

N >1,000 50 

150 >1,000 30 

700 

2,000 

L 

700 

L 

L 

Limits of determination-- 0.5 200 0.02 10 l 10 20 5 5 10 100 10 50 200 

1Atomic absorption. 

Lab. No. Desaription 

AGJ973-----Quartz-tourmaline veined granite (in float). 

974-----Mica schist (in float, possibly from inclusion). 

97 5-----Muscovite-quartz-arsenopyrite greisen adjacent to 

tourmaline greisen AGJ976. 

cumulative frequency distribution diagrams. These are 

given with geochemical maps in the supplementary 

open-file report (Hawley and Clark, 1969). 

ELement Median 

Ag------ < 0.5 

As------ <200 

Au------ <.02 

Cu------ 70 

Pb------ 15 

Zn------ <200 

Lower Limit of anomaLous 

concentrations 

(parts per milLion) 

0.5 

Detected (limit of determination is 200 ppm) 

.02 

150 

30 

200 

Because of the high limits of detectability of silver, 

arsenic, gold, and zinc compared to their r e 1 at i v e 

scarcity in the area, medians could not be calculated 

directly. However, projections on the cumulative frequency diagrams show that the median concentrations 

are probably less than one-half of the limit of anomalous concentration. Antimony and tin are found in a 

very few samples; these elements are likewise scarce 

compared to their analytical detectability and are considered anomalous if seen spectrographically. 

Elements such as copper and gold (listed in the preceding section) are found locally in anomalous concentrations in stream sediments not only below known 

occurrences but also in drainages in which metallized 

rocks have not yet been found. The analyses presented 

graphically in the companion open-file report (Hawley 

and Clark, 1969) are summarized in figure 8. The map 

shows which elements are present in anomalous concentrations in stream-sediment samples of the area. 

13 

Lab. No. Desaription 

AGJ976-----Tourmaline greisen. 

977-----Quartz-muscovite greisen exposed. 

978-----Quartz-arsenopyrite vein parallel toccntact of granite and country rock. 

ANOMALIES RELATED TO KNOWN DEPOSITS 

OR OCCURRENCES 

Anomalies related to known occurrences are found 

in several areas, such as near Lookout M':luntain, the 

Long Creek prospect, Golden Zone, Carvon Creek, 

upper Partin Creek, and the Ohio Creek tin-bearing 

greisen. Maximum metal concentrationE' in stream 

sediments from these areas are shown in table 6. In 

the upper Partin Creek area, anomalous corcentrations 

of one or more metals persist at least 2 miles below 

the occurrence; in Bryn Mawr Creek, below the Golden 

Zone, several elements persist for more th?.n 27.1 miles, 

and arsenic remains at or above 3,00C ppm to the 

mouth of the creek. Mineralization in and near Canyon 

Creek is marked mainly by high metal corcentrations 

in tributary valleys but not in the broad alluviated valley of Ohio Creek. In the upper Ohio Creek area, maximum concentrations of tin and other el~ments and 

visible greisen (northernmost sample) are found in 

the gulch. However, the presence of copper, antimony, 

zinc, and a trace of tin and tungsten in a tributary to 

Ohio Creek below the occurrence suggests that related 

mineralization extends east of the granite stock into 

the next drainage basin. 

ANOMALIES OF UNKNOWN ORIGIN 

Anomalies of unknown origin are grouped into two 

types: ( 1) Those with abundant metals, and (2) t h o s e 

with metal concentrations at or near the limit of anomalous values. The concentrations in the first type are 

similar to those found below known metal c ccurrences 

and probably indicate nearby mineralized rocks. The 

anomalies in Coal Creek and Long Creek (fig. 8) are 

of this type; both show gold equal to or greater than 

0.1 ppm, while the Coal Creek sample has 3 ppm Ag 

and 700 ppm Zn, and the richest Long Creek sample 
T. 

19 

S. 

Qc 

,' 

,' 

-. 

: 

: 

,-r 

\\-r 

R. 10 w_ 

Qc 

EXPLANATION 

f;K9;~\i?_rl Alluvium 

Colluvium ~ and glacial 

deposits 

Coal-bearing t eds 

~~;I 

Granite porphyry 

Diorite and quartz diorite porphyry, 

locally garnetiff'rous 

[>s~<i Serpentinite, basalt. a"'d gabbro 

undivided 

Argillite and graywacke 

..... 

~ <( 

i= 

c:: 

LLJ 

I-

~Tp Metagraywacke 

Qc 

,• 

Contact 

Long-dashed where approximme; short-dashed 

where inferred; dotted where concealed 

Fault 

Long-dashed where approximate; dotted 

where concealed 

Base from U.S Geolog1cal Survey 

1·63,360, Healy B-5, 1953;8-6,1954 Geology by M A.Herdr~ck, A l Clark, and C. C Howley, 1968 !f. ~ ~ 

1 MILE 

Inclined Vertical Overturned 

Strike and dip of beds 

: .. :.·. 

Dissemi~~t~d sulfides 

_.,-lA 

Sample locality 

Table 5 

Figure 5,--Geologic map of the northeastern part of the Golden Zone-Silver King mineralized area showing sample locations. 

has 500 ppm As and 150 ppm Cu. A high concentration 

of chromium and nickel at Coal Creek (fig. 2) suggests 

that metallized rocks may occur in or near serpentinite. 

Anomalies of the second type are represented mainly by samples from Shotgun and McCallie Creeks and 

from the upper Costello Creek area (fig. 8). Shotgun 

and McCallie Creeks head in the interlayered basaltlimestone terrane (fig. 1), which is the host rock of 

deposits at Partin and Canyon Creeks; both streams 

have multiple-element anomalies. In contrast, only 

one of four samples from Little Shotgun Creek, which 

heads in red beds, has an anomalous amount of metal. 

The metals found in Shotgun and McCallie Creeks are 

gold, copper, and, less commonly, zinc, arsenic, and 

14 

antimony. These metals also characterize the occurrences at Partin and Canyon Creeks, and the data suggest that hitherto undiscovered mineral occurrences 

may be located in the limestone-basalt terrane between 

these two areas. The metal concentrations of the samples from Shotgun and McCallie Creeks are near the 

limit of anomalous concentrations; that is, gold ranges 

only from 0.02-0.06 ppm, copper is 150 ppm, arsenic 

and antimony are barely detected, and zir.c is 200 ppm. 

Although these relatively low concentrations may indicate only weak metallization, most cf the sample 

sites are more than a mile from the mo~t likely host 

for lode occurrences-the limestone ani basalt-and 

could, therefore, indicate normal downstream dilution 

of an anomaly. 
Table 5.--Analyses of samples from occurrences in the Golden Zone-Silver King mineralise1 area 

[Analysts: Joe Curry, E. E. Martinez, and R. L. Miller. Gold analyses by atomic absorption. Other 

analyses are semiquantitative spectrographic and are reported in the series 0.1, 0.15, 0.2, 0.3, 

0.5, 0.7, 1.0, 1.5, and so on, or by the following symbols: N, not detected; L, de~ecte~ but below limit of determination. Results are given in parts per million except Fe and T~, wh~ch are 

given in percent. Samples 1--5 (from Lookout Mountain) taken from felsite and quartz porp~yry, 

samples 6 and 7 from a shear zone, sample 8 from breccia, and samples 9-11 from black ar~illite 

and quartzite] 

Sample Lab. Field 

No. No. No. Ag As Au 8i Cd Cu Mo Pb Sb Sn Zn Fe Ti 

Costello Creek (sample localities shown in fig. 5) 

lA AGJ645 HB6--M53 0.7 >1o,ooo 0.3 150 N 500 L 10 N 15 N 15 0.7 

2A 646 M54 • 5 200 .4 30 N 1,000 N L N L N 20 1 

3A 956 MH-835 L N N N N 70 N L N 15 N 10 .5 

4A 957 836 .7 300 • 3 30 N 150 L N N N L 7 • 3 

SA 958 837 3 400 N 30 N 700 L N N 50 L 10 .7 

6A 959 8378 L L N N N 10 N 20 N L L 3 .15 

7A 641 HB6-M44 7 N • 2 N N 500 N L 150 N N 5 .7 

Camp Creek (sample localities shown in fig. 5) 

18 AGJ630 68ACK140 L N N N N 70 N 10 N N N 5 0.2 

28 631 141 L N N L N 70 L 15 150 N L 10 • 5 

38 632 147 L L .02 L N 10 N 100 N N L 10 • 5 

48 633 148 L N N L N 100 L 150 L N 700 7 .5 

58 634 149 • 5 L N L N 10 7 50 L N 500 7 • 5 

68 635 150 .7 N .6 L 30 500 20 50 150 N 1,000 15 1 

Lookout Mountain (sample localities shown in fig. 6) 

1 AGJ935 68ACs858D 10 N N N N 20 N 300 N 10 500 3 0.05 

2 936 858E 15 L N N N 10 N 150 L 30 500 2 .05 

3 937 858F 3 L N N N 15 N 150 N 15 500 3 .05 

4 939 866 30 L .04 N N 150 L 700 L 50 L 7 • 5 

5 941 8688 .7 N N N N 20 L 1,500 300 50 700 3 .2 

6 933 8588 3 N N N N 30 N 150 N 15 500 5 .5 

7 934 858C 3 N N N N 100 L 70 N 10 200 7 • 5 

8 938 861 15 N N N N 20 N 500 L 30 700 3 .15 

9 932 857 1 N N N N 20 L 30 N 10 N 3 .7 

10 697 862 1 N N N N 20 1 30 N L N 3 .5 

11 940 867 • 5 N N N N 20 N L N N L 3 • 3 

Long Creek prospect (sample localities shown in fig. 7) 

A AGJ809 68ACK230A 500 >10,000 2.8 300 500 3,000 7 3,000 3,000 100 >10, 000 20 0.01 

B 810 8 1 L • 2 15 N 500 L 20 N N L 7 • 3 

c 811 c 200 >10,000 3. 2 500 70 1,000 7 1,500 1,500 N 3,000 20 .03 

D 812 D 2 1,500 • 2 L N 300 L 30 N N N 7 .2 

E 813 E 1 N .04 N N 200 L 15 N N L 5 .3 

F 814 F 2 N .1 N N 200 L 15 N N N 7 .5 

G 815 G • 7 300 .06 N N 200 L 10 N N N 7 .5 

H 816 H 100 >10,000 3.1 150 N 3,000 7 1,000 1,500 10 300 >20 .02 

I 817 I .7 300 .06 L N 300 L 15 N N L 7 .5 

J 818 J 1.5 200 .06 L N 300 5 20 N L L 7 .5 

K 819 K 5 300 . 3 15 N 500 L 50 100 L L 7 .3 

L 820 L 70 >10,000 3. 6 150 N 700 7 300 1,000 L 300 15 .03 

M 821 M L L .04 N N 150 L N N N N 1.5 .15 

N 822 N 5 >10,000 11 1,000 N 700 7 50 500 N N 10 .07 

0 823 0 L L .04 N N 200 L 10 L L L 7 • 5 

p 824 p L 300 .06 N N 150 L 10 N L N 3 .03 

Q 825 Q L N .04 N N 150 L L N L L 7 .5 

R 826 R 7 3,000 • 2 10 30 700 L 200 L 100 700 7 .3 

s 827 s 700 >10,000 3.2 150 500 3,000 7 3,000 2,000 700 >10,000 >20 .015 

T 828 T 1.5 500 .06 N N 150 5 30 N 15 300 7 .5 

X 829 232 70 1,500 1.9 300 N 1,500 7 100 N :)..5 200 20 • 3 

Limits of 

determination-------- 0. 5 200 0.02 10 20 5 10 100 10 200 o.os 0.001 

15 
EXPLANATION 

LLlo::: 

I-<( 

Approximate contact 

Surficial deposits 

}

d:: >-

~z 

0 Concealed contact of 

porphyry-breccia body 

Breccia of porphyry, 

argillite, and quartzite 

~ 

Inclined Vertical 

Strike and dip of cleavage 

--0 

Sample locality 

Tah/e 5 

Felsite and quartz 

porphyry }! IArgillite and quartzite 

}

ou 

W-

...JO 

<(N 

a.. 

0 1000 2000 FEET 

CONTOUR INTERVAL 100 FEET 

DATUM IS MEAN SEA L'OVEL 

Geology by Sandra H. B. Clar~.1968 

Base from U.S Geolog1cal Survey 

1:63,360. Healy A-6. 1953 

Figure 6.--Geologic map of the Lookout Mountain area. 

Table 6.--Mazimum element concentrations, in parts per 

mil lion, in stream-sediment samp~es be~o~ kno~n deposits and occurrences 

[N, not detected; L, detected but below limit of determination] 

Lookout Long Golden Canyon Partin Ohio 

Mountain Creek Zone Creek Creek Creek 

Ag---- 0.7 7 3 2 0.7 15 

As---- 200 N 5,000 200 700 200 

Au---- N N . 7 . 02 • 4 N 

Cu---- 150 70 300 500 500 300 

Pb---- 70 70 200 70 30 20 

Sb---- N N N L L L 

Sn---- N N N 150 N 200 

Zn---- 500 L 200 500 200 700 

Anomalous concentrations of zinc, ~rsenic, copper, 

and lead seem to characterize an area drained by upper 

Costello Creek. The same elements, especially zinc, 

are also found at several sites in lower Ohio, Copeland, and Long Creeks, and anomalous concentrations 

of zinc occur in upper Long and Copeland Creeks and 

in the area due west of the Golden Zone. The concentrations of the elements found in upper Costello Creek 

and the other sites mentioned are generally near the 

minimum for an anomaly; that is, inpartsper million: 

Ag, 0.5-0.7; As, detected; Cu, 150; Pb, 30; and Zn, 

16 

200-300. The distribution of these low values suggests 

a broad mineralized zone centered around the Golden 

Zone-Silver King area. 

SUMMARY AND RECOMMENDATIONS FOR P~OSPECTING 

Deposits or occurrences of copper-, gold-, silver- , 

and tin-bearing rocks are widely distributed throughout 

the area studied (fig. 1), and anomalouQ amounts of 

chromium or nickel are found at scattered localities 

along a linear zone of serpentinites (fig. 2 ). Although 

many of the known occurrences appear to be small or 

of low grade, the potential of the area appears good 

because of (1) the total numberofoccurrences, (2) the 

presence of favorable host rocks such rs limestone, 

basalt, and tuff, (3) the diverse elements contained in 

the mineralized rocks, and (4) theexisterr;eofaknown 

significant deposit at the Golden Zone. 

An attractive site for exploration is the elongate 

Partin Creek-Canyon Creek mineralized area. The 

occurrences in the area are poorly known, but sulfidized rocks crop out over distances measured in 

thousands of feet at Partin Creek and Canyon Creek, 

and the host rocks are favorable for replacement deposits. The geochemical anomalies in Shotgun and 
Index map of part of Healy A-6 quadrangle 

showing location of prospect 

N 

1 100 50 0 100 FEET 

Quartz 

~ 

~ porphyry 

Sulfide ------vein 

'~:.: 

Sulfide-rich dump material 

,,~ ..... 

-;,IIJll'•'nuoU,,~ 

Trench 

::~ 

Pit 

:··n• .. ,,,,,...!: 

.. IJ,,,.,,,, ... 

Dump material 

D,du,5 

Sample locality 

C-apita/letter refers to table 5; lower case letters 

show type of material 

v, vein 

di, dike 

du, dump 

Number is length of-channel sample, in feet. Sample X collected approximately 300ft s?uthwest 

of samples Q and P 

Figure 7.--Map of Long Creek prospect showing sample locations. 

McCallie Creeks are probably caused by undiscovered 

mineralized rocks in the limestone and basalt in the 

headwater areas. 

The granite with tin-bearing greisen in upper Ohio 

Creek has not been thoroughly investigated, and the 

amounts of tin at Canyon Creek and the Long Creek 

deposit are of interest. 

17 

The discovery of mineral occurrences in the northern part of the area near Costello and Camp Creeks 

suggests that sparse outcrops north of that area, such 

as the outcrops along the Bull River, shouldl~ examined. 
5232.8, Ruby 

2 0 2 

EXPLANATION 

0 

Stream-sediment sample locality 

(I 

No element present in anomalous concentratiC'n 

.. g.Zn 

Stream-sediment sample locality 

Showing one or more elements present 

in anomalous conant ration 

Ag. silver As. arsenic 

Au. gold Cu. copper 

Pb.lead 

Sb. antimony 

Zn. zinc Tin ( Sn) and tungsten (W )shown if detected 

-oSample locality on tributary stream 

not shown on base map 

4 MILES 

Figure B.--Elements present in anomalous concentration in stream-sediment samples. 

l8 
SELECTED REFERENCES 

Capps, S. R., 1919, Mineral resources of the upper 

Chulitna region: U.S. Geol. Survey Bull. 692, p. 207-

232. 

Hawley, C. C., and Clark, A. L., 1968, Occurrences of 

gold and other metals in the Upper C h u 1 i t n a district, Alaska: U.S. Geol. Survey Circ. 564, 21 p. 

Hawley, C. C., and Clark, A. L., 1969, Geochemical 

maps of an area northwest of the Chulitna River 

central Alaska Range: U.S. Geol. Survey open-fil~ report. 

19 

Ross, C. P., 1933, Mineral deposits near the west fork 

of the Chulitna River, Alaska: U.S. Geol. Survey 

Bull. 849-E, p. E289-E333. 

Tuck, Ralph, 1934, The Curry district, Alaska: U.S. 

Geol. Survey Bull. 857, p. 99-140. 

Turekian, K. K., and Wedepohl, K. H., 1961, Distribution of the elements in some major units of the 

earth's crust: Geol. Soc. America Bull., v. 72, no. 2, 

p. 175-192.