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Chapter E 

Mineral Resources of the GOld Creek 

and Sperry Creek Wilderness Study Areas, 

Malheur County, Oregon 

By JAMES G. EVANS, JAMES G. FRISKEN, ANDREW GRISCOM,· 

and DON L. SAWATZKY 

U.S. Geological Survey 

MICHAEL S. MILLER 

U.S. Bureau of Mines 

U.S. GEOLOGICAL SURVEY BULLETIN 1741 

MINERAL RESOURCES OF WILDERNESS STUDY AREAS: 

EAST-CENTRAL OREGON 
U.S. DEPARTMENT OF THE INTERIOR 

MANUEL LUJAN, JR., Secretary 

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director 

Any use of trade, product, or firm names 

in this publication is for descriptive purposes only 

and does not imply endorsement by the U.S. Government 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1990 

For sale by the 

Books and Open-File Reports Section 

U.S. Geological Survey 

Federal Center, Box 25425 

Denver, CO 80225 

Library of Congress Cataloging-in-Publication Data 

Mineral resources of the Gold Creek and Sperry Creek Wilderness study 

areas, Malheur County, Oregon I by james G. Evans ... [et al.]. 

p. em. - (Mineral resources of wilderness study areas-eastcentral Oregon : ch. E) (U.S. Geological Survey bulletin : 17 41-E) 

Includes bibliographical references. 

Supt. of Docs. no.: I 19.3: 1741-E 

1. Mines and mineral resources-Oregon-Gold Creek Wilderness. 

2. Mines and mineral resources-Oregon-Sperry Creek Wilderness. 

3. Gold Creek Wilderness (Or.) 4. Sperry Creek Wilderness (Or.) 

I. Evans, james George, 1938- . II. Series. Ill. Series: U.S. 

Geological Survey bulletin; 1741-E 

QE75.B9 no. 1741-E 557.3 s-dc20 90-13945 

[TN24.07] [553' .09795'97] CIP 
STUDIES RELATED TO WILDERNESS 

Bureau of Land Management Wilderness Study Area 

The Federal Land Policy and Management Act (Public Law 94-579, October 21, 

1976) requires the U.S. Geological Survey and the U.S. Bureau of Mines to conduct mineral 

surveys on certain areas to determine the mineral values, if any, that may be present. Results 

must be made available to the public and be submitted to the President and the Congress. 

This report presents the results of a mineral survey of the Gold Creek (OR--003--033) and 

Sperry Creek (OR--003--035) Wilderness Study Areas, Malheur County, Oregon. 

CONTENTS 

Summary El 

Abstract El 

Character and setting El 

Identified resources El 

Mineral resource potential E2 

Introduction E2 

Area description E2 

Previous and present investigations E3 

Appraisal of identified resources E3 

Methods E3 

Mining history E3 

Appraisal of commodities examined E4 

Diatomite E4 

Stone E4 

Basalt E4 

Sand and gravel E5 

Other industrial materials E5 

Gold and associated elements E6 

Geothermal energy E6 

Oil and gas E6 

Recommendations for further study E7 

Assessment of mineral resource potential E7 

Geology E7 

Geochemical studies ElO 

Geophysical studies E12 

Mineral and energy resource potential El3 

References cited El4 

Appendixes E17 

Definition of levels of mineral resource potential and certainty of 

assessment E18 

Resource/reserve classification E19 

Geologic time chart E20 

FIGURES 

1. Index map showing location of Gold Creek and Sperry Creek Wilderness Study 

Areas, Malheur County, Oregon E2 

2. Map showing mineral resource potential, identified mineral resources, and 

generalized geology of Gold Creek and Sperry Creek Wilderness Study Areas, 

Malheur County, Oregon ES 

3. Total-field aeromagnetic anomaly map of area including Gold Creek and Sperry 

Creek Wilderness Study Areas, Malheur County, Oregon El2 

TABLE 

1. Summary of identified mineral resources and occurrences in the Gold Creek and 

Sperry Creek Wilderness Study Areas, Malheur County, Oregon E5 

Contents V 
Mineral Resources of the Gold Creek 

and Sperry Creek Wilderness Study Areas, 

Malheur County, Oregon 

By James G. Evans, James G. Frisken, Andrew Griscom, 

and Don L. Sawatzky 

U.S. Geological Survey 

MichaelS. Miller 

U.S. Bureau of Mines 

SUMMARY 

Abstract 

At the request of the U.S.Bureau of Land Management, 

the Gold Creek (OR-003-033) and Sperry Creek (OR-003-

035) Wilderness Study Areas, comprising approximately 

15,780 and 5,600 acres, respectively, were evaluated for mineral resources and mineral resource potential. Throughout 

this report, "wilderness study area" and "study area" refer to 

the combined 21,380 acres for which mineral surveys were 

requested. The U.S. Geological Survey and the U.S. Bureau of 

Mines conducted geologic, geochemical, and geophysical 

surveys to assess the identified mineral resources (known) and 

mineral resource potential (unknown) of the study area. Field 

work for this report was carried out in 1987, 1988, and 1989. 

The study area contains more than 100,000 short tons (st) 

of diatomite, 80,000 st of building and decorative stone, and 

large amounts of basalt suitable for crushed aggregate or the 

production of basalt fiber. The study area also contains 

865,000 yd3 of sand and gravel resources. In addition, 

fanglomerate, possibly suited for sand and gravel, covers 3,100 

acres. Gold, optical calcite, zeolite, and perlite have been 

found locally in small uneconomic amounts. A geothermal 

energy occurrence is present. 

Part of the Gold Creek Wilderness Study Area has high 

mineral resource potential for gold, and a very small part of 

that has low resource potential for geothermal energy resources. The northern part of the Gold Creek Wilderness 

Study Area and the eastern part of the Sperry Creek Wilderness Study Area have moderate mineral resource potential for 

gold, silver, and mercury. The entire study area has low potential for oil and gas energy resources. 

Manuscript approved for publication, August 20, 1990 

Character and Setting 

The Gold Creek and Sperry Creek Wilderness Study 

Areas (fig. 1) are located about 33 mi southwest of Vale, 

Oreg. The study area is part of the Owyhee Plateau south of 

the Malheur River and consists of several deep canyons cut 

into a broad plateau of flat uplands, low hills, and mesas. 

These canyons are incised as deeply as 1,400 ft into the 

plateau. The Malheur River, along the north side of the 

study area has cut down about 2,400 ft through the plateau. 

The study area is underlain by Miocene or older, Miocene, 

Pliocene, and Quaternary sedimentary, volcanic, and pyroclastic rocks and deposits (fig. 2; see "Appendixes" for 

geologic time chart). Numerous steep faults cut the study 

area. 

Identified Resources 

More than 100,000 short tons (st), of marginally economic diatomite resources were identified inside the east 

boundary of the study area, and at least 2,000,000 st were 

identified outside the eastern boundary. The study area contains 80,000 st of marginally economic building and decorative stone and large amounts of basalt suitable for crushed 

aggregate or production of basalt fiber. Subeconomic resources of sand and gravel total 865,000 yd', and an additional 3,100 acres within the study area are underlain by 

fanglomerate that may be suitable for sand and gravel production. Gold, optical calcite, zeolite, and perlite are present 

in the study area in small uneconomical amounts. A geothermal energy occurrence, possibly suitable for domestic 

space heating, is present along the north boundary of the 

study area. 

- Mineral Resources of the Gold Creek and Sperry Creek Wilderness Study Areas, Malheur County, Oregon E1 
Mineral Resource Potential 

Part of the north-central Gold Creek Wilderness Study 

Area has high mineral resource potential for gold, and a· 

small part of that area along the north boundary has low 

resource potential for geothermal energy. A large part of 

the northern Gold Creek Wilderness Study Area and the 

eastern part of the Sperry Creek Wilderness Study Area 

have moderate resource potential for gold, silver, and mercury. The entire study area has low potential for oil and gas 

energy resources. 

INTRODUOION 

This mineral survey was requested by the U.S. Bureau of Land Management and is the result of a cooperative 

effort by the U.S. Geological Survey and the U.S. Bureau 

· of Mines. An introduction to the wilderness review process, 

mineral survey methods, and agency responsibilities was 

provided by Beikman and others (1983). The U.S. Bureau 

of Mines evaluates identified resources at individual mines 

and known mineralized areas by collecting data on current 

and past mining activities and through field examination of 

43° 

50' 

43° 

40' 

118°00' 

APPROXIMATE BOUNDARY \ 

OF ' 

SPERRY CREEK 

WILDERNESS STUDY AREA 

(OR-003-035) ....... _, ,p, ......... 

~ ., '?~) 

'?t.\ ( 

a-' ~o:''- 0 \ 

I 

I 

I 

\--..._ 

• South Mountain 

: r ...... _,\_ / • 1 .,"' - .... ) Monument Peak I I 

I, I / I I I I I I ,_,._, 

I I I 

I I " I I I I I / 

mines, prospects, claims, and mineralized areas. Identified 

resources are classified according to a system that is a 

modification of that described by McKelvey (1972) and the 

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

U.S. Geological Survey studies are designed to provide a 

scientific basis for assessing the potential for undiscovered 

mineral and energy resources by determining geologic units 

and structures, possible environments of mineral deposition, presence of geochemical and geophysical anomalies, 

and application of ore-deposit models. Goudarzi (1984) discussed mineral assessment methodology and terminology 

as they apply to these surveys. See "Appendixes" for the 

definition of levels of mineral resource potential and certainty 

of assessment and for the resource/reserve classification. 

Area Description 

The Gold Creek (OR--003--033) and Sperry Creek 

(OR--003--035) Wilderness Study Areas cover 21,380 acres 

of the Owyhee Plateau south of the Malheur River (fig. 1). 

Several steep, rocky canyons, including the canyons of Gold 

Creek and Sperry Creek, cut into the plateau. These canyons 

and the steep-sided intervening ridges make up most of the 

Harper 

minin~" 

( 

I 

I 

I 

I 

I 

I 

/ 

I 

I 

I 

/ 

I 

I 

\ 

I 

I 

I 

/ 

I 

I 

I 

/ district 

I " 

I 

\ 

\ 

I , 

/ 

APPROXIMATEBOUNDARY OF '-\ \ [3 GOLDCREEK I 

WILDERNESS STUDY AREA I OREGON • 

(OR-003-033) \ 

I ' 

I AREA OF MAP I 

I 

I 

I 

/ o· 5 MILES I 

I 

Figure 1. Index map showing location of Gold Creek and Sperry Creek Wilderness Study Areas, Malheur County, Oregon. 

Dashed lines, unpaved roads. 

E2 Mineral Resources of Wilderness Study Areas: East-Central Oregon 
study area. A small part of the southern part of the study 

area is on the flat uplands of the plateau at the heads of the 

canyons. The total relief is 2,662 ft from a low point of 

2,660 ft in the northeast comer of the Gold Creek Wilderness Study Area along the Malheur River to 5,322 ft in the 

southwest comer near Tims Peak. Some of the canyons are 

as deep as 1 ,400 ft. The arid climate supports sagebrush, 

rabbit brush, and sparse native grasses. Riparian areas and 

springs support a greater variety of plants, including lowgrowing willows, bitter cherry, golden currant, rose, sedges, 

and rushes. Parts of the study area are used for cattle and 

sheep grazing. The study area also supports mule deer, antelope, coyote, and numerous species of small mammals, 

birds including raptors, and reptiles including the western 

diamondback rattlesnake. The northern part of the study 

area provides critical winter range for deer and antelope. 

Dirt roads and jeep trails traverse much of the boundary and cross parts of the study area (fig. 1). Access to most 

of the study area is easiest near its north boundary from 

U.S. Highway 20, which follows Malheur River canyon. 

This highway connects with dirt roads that ascend South 

Trail Creek on the west side of the study area and the North 

Fork Squaw Creek along the east side of the study area. 

Branching jeep trails provide access to the southern part, 

which can also be reached by better jeep trails that branch 

from the Shumway Grade gravel road south of Juntura, 11 

mi west of the study area. 

Previous and Present Investigations 

Geologic mapping that included parts of the study 

area was carried out by Hagood (1963) at the scale of 

1:31,680 and by Haddock (1967) at the scale of 1:63,360. 

Their work was incorporated into a treatise on the stratigraphy of the region by Kittleman and others (1965) and a 

geologic map of the region by Kittleman and others (1967) 

at the scale of 1:250,000. Walker (1977) later incorporated 

Hagood's and Haddock's mapping into a geologic map of 

eastern Oregon at the scale of 1:500,000. Reconnaissance 

geochemical studies and initial mineral resource appraisals 

of many wilderness study areas of eastern Oregon, including the Gold Creek and Sperry Creek Wilderness Study 

Areas, were made by Gray and others (1983) and Bukofski 

and others (1984). 

The U.S. Geological Survey carried out field investigations in the study area during 1988. This work included 

geologic mapping at the scale of 1:24,000, geochemical 

sampling, and review and interpretation of geophysical surveys (gravity, aeromagnetic, gamma ray spectrometer, remote sensing). 

The U.S. Bureau of Mines investigation was conducted 

by personnel from the Western Field Operations Center, 

Spokane, Wash., during 1987, 1~88, and 1989. Details of 

sampling methods and analyses are reported by Miller (1989). 

APPRAISAL OF IDENTIFIED RESOURCES 

By MichaelS. Miller 

U.S. Bureau of Mines 

Methods 

Initial studies of the Gold Creek and Sperry Creek 

Wilderness Study Areas included a literature search and an 

examination of Malheur County and U.S. Bureau of Land 

Management mining claim and mineral lease records. U.S. 

Bureau of Mines production records were also searched. 

Field studies, including a search for all mining activity and 

mineralized zones within the study area, were conducted 

during 16 days between May and August 1988. Mineralized zones were examined, mapped, and sampled. Those 

close to the study area were also examined to determine if 

they extended into the study area and to understand the 

regional mineralization. Ground and air reconnaissance were 

used to search for extensions of mineralized zones from 

known mineral sites. Sample collections included 188 rock 

and 12 alluvial samples (Miller, 1989). The results of the 

investigation are summarized in table 1. 

Mining History 

Small pits and trenches of unknown age were found 

along quartz veins west and southwest of the mouth of 

Gold Creek. Underground workings, not found in this study, 

reportedly were dug about 1900 by Chinese miners at hot 

springs along the north boundary of the study area (fig. 2) 

(Ben Jordan, oral common., 1988). China Creek, north of 

the Malheur River, may have been named to commemorate 

these early miners. The Frying Pan and Harry Boy lode 

claims in the study area along Gold Creek were recorded in 

1913 (Miller, 1989). A group of four placer claims, the 

Fiery, Firebrand, Firetrap, and Fire Bug, date from 1917 

and were described as lying about 1 mi east of the Gold 

Creek Wilderness Study Area. The Gold Peak lode claim, 

location uncertain, was recorded in 1925. In 1928, the Lost 

Hope and Fabled Goose lode claims were located near the 

mouth of Gold Creek. The Treasure 1-4 lode claims were 

located in 1958 on a hill north of the Malheur River across 

from Sperry Creek. The Morning Side lode claim was staked 

in 1967 west of the mouth of Gold Creek. The Gold Creek 

No. 1 lode claim was located about 1.5 mi southwest of the 

mouth of Gold Creek in 1979 by Ben Jordan, Raymond 

Jordan, and Curt Hysell. Manville Products Corporation 

staked 34 lode claims near the mouth of Gold Creek in 

1988. Most of the older claims were not found in our 1988 

studies. Other current activity is in the Harper Basin mining 

district, about 15 mi east of the study area, where Manville 

was investigating diatomite occurrences in 1987 (Ramp, 

1988, p. 42-43) and American Copper and Nickel Company, 

Mineral Resources of the Gold Creek and Sperry Creek Wilderness Study Areas, Malheur County, Oregon E3 
Inc., was exploring for gold in 1988 (Ferns, 1989, p. 29). 

Diatomite is being mined by Eagle-Picher Industries at 

Drinkwater Pass, about 30 mi northwest of the study area. 

About 40 mi southeast of the study area, Teague Mineral 

Industries is mining bentonitic clay and zeolites. Quarries 

northeast of the study area along U.S. Highway 20, have 

been operated more or less continuously for decades to supply stone and aggregate for construction and road maintenance. No mineral patents and no oil and gas or geothermal 

energy leases or applications are known for the study area 

Appraisal of Commodities Examined 

Diatomite 

Diatomite that could be used for filter aids (69 percent), fillers (16 percent), and other uses (15 percent) occurs 

in and adjacent to the study area. At least 30 acres of 

diato.mite having an estimated thickness of 5 ft occurs adjacent to and inside the east boundary of the Gold Creek 

Wilderness Study Area. Marginally economic resources of at 

least 100,000 short tons (st) of diatomite occur inside the 

study area, and about 2,000,000 st occur east of the study area 

boundary in beds about 10ft thick. Diatomaceous samples 

from the Fiery Placer mining claim group are from thin, 

silty, sandy, tuffaceous beds and do not constitute resources. 

Diatomite samples from east of the study area have 

block densities of 32 to 43.5 pounds per cubic foot (lbs/ft3

) 

and an average block density of 36.8 lbs/ft3

• Samples used for 

resource estimates contain an average of 77.6 percent silica 

(Si02), 5.04 percent alumina (Al20 3), and 2.26 percent iron 

oxide (Fe2

0 3

) and had an average loss on ignition of 11.86 

percent. Moore (1937, p. 113) considered diatomite having 

a block density of less than 30 lbs/ft3 to be excellent; block 

densities from 30 to 35 lbs/ft3 are considered good, those 

from 35 to 40 lbs/ft3 are fair, and those greater than 40 lbs/ 

ft3 are poor. Diatomite samples in and east of the Gold 

Creek Wilderness Study Area, therefore, are rated as poor 

to good quality; however, for some uses, denser diatomite 

is required. 

Preliminary surface mining costs for diatomite were 

estimated· by the methods of Benjamin and Gale (1984) 

using January 1988 costs. A 500,000-st deposit mined by 

open-pit methods at 100 st per day would cost from an 

estimated $8 per st ($/st) with no stripping tp $21/st with a 

2: 1 stripping ratio. Although other beneficiation methods 

are possible, flotation has been tested by the U.S. Bureau of 

Mines for impure diatomite (Norman and Ralston, 1940). 

Flotation concentration costs were estimated at $30/st for a 

500,000-st deposit mined at 100 st per day. Additional processing costs were not estimated because of the many possible end uses. Transportation for 50 mi at 25 mi per hour 

(mph) in 25-ton trucks was estimated to cost about $14/st 

Concentration by flotation or other methods would lower 

totaf transportation costs. The diatomite beds in and adjacent to the Gold Creek Wilderness Study Area are considered to be marginally economic inferred resources (U.S. 

Bureau of Mines and U.S. Geological Survey, 1980, p. 2) 

because of their low grade and the competition from established mines, primarily from Eagle-Picher's mine only 30 

mi away and from others in California and Nevada 

(Meisinger, 1989, p. 50-51). 

Stone 

Weathered lichen-covered stone in the study area, 

mainly basalt, andesite, and rhyolite, breaks into irregular 

chunks and slabs that can be used for wall facing, flagging, 

and decorative purposes. At least 2 mi2 of the study area are 

covered almost continuously by stones of this type. One 

piece of decorative stone weighing 150 lbs is estimated to 

occur on each 100 square ft (ft2), and, therefore, 1 square mile 

of land is estimated to contain 20,000 st of stone suitable 

for landscaping. Each 100 ft2 also contains about five pieces 

of stone weighing 30 lbs apiece, so the same square mile is 

estimated to contain 20,000 st of stone suitable for wallfacing. Preliminary costs for mining decorative stone in the 

study area were estimated by the methods of Benjamin and 

Gale (1984). Cost of mining stone at the surface, at 50 st/ 

day, was estimated to be about $14/st (January 1988 costs). 

Transporting stone in 25-ton trucks for 150 mi at 45 mph 

was estimated to cost about $22/st (January 1988 costs). 

Similar rock in Boise, Idaho, was selling for between $100 

and $200/st retail in 1988. Therefore, building and decorative stone in the study area is considered to be a marginal 

economic inferred resource (U.S. Bureau of Mines and U.S. 

Geological Survey, 1980, p. 2) of at least 80,000 st. Decorative stone might be mined from the study area when existing resources nearer markets are depleted. 

Basalt 

Stone quarries near U.S. Highway 20 supplied large 

quantities of crushed rock, mainly basalt, that were used 

during highway construction. Two quarries, from which a 

minimum estimate of 1 million st of stone were mined are 

about 0.5 mi east of the Gold Creek Wilderness Stud.y Area. 

No resources of stone for crushing were estimated for the 

study area because large quantities of suitable basalt of good 

quality outside the study area would probably be mined first. 

Basalt fibers can be produced from basalt similar to 

that in the study area. Although this use is currently limited, 

future developments in the field of thermal insulation and 

high-strength reinforcement may result in significant markets. Basalt fibers can replace glass fibers in many applications (Subramanian and others, 1977). Samples of basalt 

from the northeastern part of the study area contain an average of about 16 percent A~0 , 12 percent Fe2

0 3, 5 percent 

magnesia (MgO), 48 per.sent Si02, and 1.8 percent titania 

(Ti02). This composition, inferred to be typical throughout 

E4 Mineral Resources of Wilderness Study Areas: East-Central Oregon 
the study area, is similar to that of basalts reportedly used 

for basalt fiber production (Subramanian, 1977, p. 5). Basalt suitable for production of fibers occurs throughout the 

study area and is also abundant in the region. Even though 

the quantity and quality of basalt in the study area would 

probably allow mining the rock for fiber production, the 

basalt is unlikely to be mined in the future because of the 

abundance of similar rock closer to population centers. 

Sand and Gravel 

Sand and gravel occurs on benches in the northern 

part of the study area. Large amounts of sand and gravel 

also occur near the mouths of some of the drainages in the 

study area. The sand and gravel, which is derived from 

basalt and rhyolite, consists of silt, sand, pebbles, cobbles, 

and boulders that are subrounded to angular. Constituent 

clasts include opal, chalcedony, obsidian, and vitrophyre. 

Sand and gravel that covers about 30 acres of terraces in the Gold Creek Wilderness Study Area is estimated 

to average 15 ft in thickness and constitute 700,000 yeP. 

Another sand and gravel deposit along Gold Creek is estimated to be 15 ft thick, 200 ft wide, and 2,000 ft long and 

constitutes about 220,000 yd3, about 75 percent of which is 

in the study area. A sand and gravel deposit in Simmons 

Gulch is estimated to be 15 ft thick, 300 ft wide, and 2,500 

ft long and constitutes about 400,000 yd3 but is just outside 

the study area. Approximately 865,000 yd3 of sand and 

gravel are present in the study area in these deposits. Sand 

and gravel deposits also occur along most of the drainages 

and in alluvial fans that cover some ridges in the northern 

part of the study area. Approximately 3,100 acres underlain 

by fanglomerate as much as 100ft thick is another possible 

source of sand and gravel in parts of the study area. The 

sand and gravel in the fanglomerate is not as accessible as 

the other sand and gravel, for which volume estimates were 

made, and the fanglomerate also contains more silt and 

clay. The sand and gravel resources may be used locally for 

minor road construction or concrete production, although 

large accumulations of sand and gravel along the Malheur 

River would probably be mined first. Therefore, the sand 

and gravel in the study area constitute inferred subeconomic 

resources. 

Other Industrial Materials 

In the northern part of the study area, much lowgrade calcite and small quantities of calcite of possible optical quality (Hughes, 1941, p. 4-5) occur in amygdules and 

breccia zones in basalt. Small quantities of optical calcite 

are used for splitting light beams and for polarizing attachments for microscopes. The calcite in the study aiea occurs 

as amygdules and as cement in scattered areas of basalt 

breccia and is associated with fibrous radiating mordenite 

and quartz. Some amygdules are two or more inches across, 

Table 1. Summary of identified mineral resources and 

occurrences in the Gold Creek and Sperry Creek Wilderness 

Study Areas, Malheur County, Oregon 

["Occurrence" indicates commodity is too low grade, too market dependent, 

or too small to classify at this time. st, short tons] 

Commodity Resource estimate Classification 

Diatomite---------- Greater than Marginally 

100,000 st in study economic 

area; greater than resource. 

2,000,000 st 

outside study area. 

Stone (decorative Greater than Marginally 

and building). 80,000 st. economic 

resource. 

Basalt (fiber)------ Large quantity, Occurrence; 

but no resources market 

estimated. dependent. 3 Sand and gravel -- 865,000 yd --------- Subeconomic 

resource; 

market and 

transport 

dependent 

Gold---------------- Low grade ---------- Occurrence. 

Calcite (optical)-- Small; no resource Occurrence; 

estimated. market 

dependent. 

Zeolite------------- Small ---------------- Occurrence. 

Perlite-------------- Small ---------------- Occurrence. 

Geothermal Small; no resource Occurrence. 

resources. estimated. 

and some breccia zones are as much as 1 ft thick and tens 

of feet long; some calcite crystals are as much as 3 in. 

across. Most of the calcite is milky, fractured, or twinned, 

but an estimated 1 percent or less of the calcite is of optical 

quality. Most of the optical calcite is in occasional pieces 

that are less than 0.5 in. by 0.5 in. by 1.0 in. Because a 

calcite prism 0.5 .in. by 0.5 in. by 1.0 in. may sell for about 

$25 according to Edmund (1989, p. 113), grade and value 

of the calcite in the study area may be adequate for mining, 

but the market is small. 

Abundant perlite float was found near the mouth of 

Simmons Gulch in the northeast comer of the Gold Creek 

Wilderness Study Area, but no perlite was found in outcrop. The perlite is probably from small or poorly exposed 

altered glassy zones in rhyolite and welded tuff. No perlite 

resources are indicated for the study area. 

White to ~y, fibrous, radiating acicular mordenite, 

a zeolite mineral, was found in amygdules in basalt flows 

and in flow-top basalt breccia in the northeastern part of the 

Gold Creek Wilderness Study Area. The mordenite is in 

masses less than 3 in. thick and 1 ft across and constitutes 

less than 10 percent of the rocks. It is associated with calcite, quartz, epidote, and chlorite. The mordenite was 

Mineral Resources of the Gold Creek and Sperry Creek Wilderness Study Areas, Malheur County, Oregon E5 
identified by X-ray diffraction and optical petrography. The 

amount of mordenite in the study area is too small to mine. 

Gold and Associated Minerals 

Gold, arsenic, antimony, bromine, mercury, molybdenum, and tungsten are concentrated in mineralized zones 

possibly related to older hot springs in the northern part of 

the study area. Most gold mineralization occurs in or adjacent to a vertical northwest-striking quartz-vein system. 

Average width of the principal vein is 2.25 ft over a length 

of at least 4,700 ft. The vein extends northwest beyond the 

north boundary of the study area and may extend farther to 

the southeast below overburden. In general, the vein system 

is narrow, lenticular, and discontinuous. A total of 24 chip 

samples and 114 grab samples was taken from the vein 

system and surrounding wall rocks in the Gold Creek 1-34. 

claim group (fig. 1). Of these samples, 70 contain 5 or more 

parts per billion (ppb) gold. The maximum concentration of 

gold is 1,960 ppb in a thin quartz vein, and 18 samples of 

quartz veins containing detectable amounts of gold average 

440 ppb. Maximum gold concentration in basalt is 220 ppb 

and 33 samples of basalt containing detectable amounts of 

gold average 30 ppb. Antimony (maximum 517 parts per 

million, ppm), arsenic (maximum, 1,860 ppm), bromine 

(maximum, 15 ppm), mercury (maximum, 0.01 percent), 

molybdenum (maximum, 1,890 ppm), and tungsten (maximum, 508 ppm) occur in the quartz vein and, more commonly, in the wall rock near the vein. Sodium is depleted in 

areas of greatest gold concentration. Gold was identified in 

the quartz veins by scanning electron microscope-microprobe anal~sis. Accessory minerals associated with the gold 

include argentite, barite, bornite, cassiterite, galena, molybdenite, and powellite. On the basis of surface indications, 

mining the quartz vein by underground methods would not 

·be feasible because of the narrow, discontinuous nature of 

the vein system and the low average gold content of the 

mineralized zone, which includes quartz and the adjacent 

mineralized basalt. However, the vein suggests a potential 

for gold at depth (see section on "Mineral and Energy Resource Potential''), and exploration is recommended (Miller, 

1989). 

The Treasure 1-4 lode claim group is about 0.5 mi 

north of the study area on the north side of the Malheur 

River. The claims are in much fractured basalt and welded 

tuff. Maximum amount of gold in six samples from these 

claims is 6 ppb, a quantity too low to be mined at present 

market value. 

Quartz-cemented rhyolite breccia and siliceous veins 

are exposed along vertical, north-striking fault zones in 

Simmons Gulch in the northeastern part of the Gold Creek 

Wilderness Study Area. The veins contain red, brown, and 

purple chalcedony and opal. One of the 13 rock samples 

contains detectable gold at 9 ppb. One sample contains 176 

ppm arsenic, and two samples contain 1,800 and 1,400 ppb 

mercury and 71.2 and 59.8 ppm antimony, respectively. 

Some samples contain detectable amounts of molybdenum 

(19 ppm maximum) and tungsten (18 ppm maximum). These 

analyses do not indicate minable grades of any elements 

but do indicate epithermal mineralization in the rhyolite in 

Simmons Gulch. 

Average gold content of 12 reconnaissance alluvial 

samples is 0.0001 ounces per cubic yard (oz/yd3

), or less if 

boulders are factored into the estimate. This is equivalent to 

$0.04 per cubic yard ($/yd3). Maximum amount of gold in 

alluvial samples from Simmons Gulch was about 0.0008 

oz/yd\ worth about $0.32/yd3• The source of gold in 

Simmons Gulch was not identified but is additional evidence of mineralization there. The value estimates were 

made by assuming that the gravel expands about 25 percent 

when excavated and that the gold is pure and worth about 

$400 per ounce. Amounts of gold in alluvial samples are 

too small to be mined at this time. 

No economic accumulations of gold or other associated elements were identified in the study area. Mining and 

beneficiation costs would exceed the value of the gold by a 

factor of at least 20 times. 

Geothermal Energy 

Hot springs occur along the north boundary of the 

Gold Creek Wilderness Study Area in an abandoned oxbow 

of the Malheur River where highway fill has created a pond 

that is approximately 500ft by 200ft. The hot springs have 

deposited low water-level tufa mounds about 30 ft across. 

The thinly laminated tufa is white with orange, yellow, and 

black staining. An old siliceous tufa deposit on the hillside 

to the south is about 30 ft above the springs and 100 ft 

across. Basalt flows near the hot springs and tufa deposits 

are cut by thin, siliceous, high-angle quartz veins surrounded 

by argillic and limonitic alteration. These veins and areas of 

argillic, limonitic basalt are hundreds of feet across, include 

the steep northwest-striking quartz-vein system described 

above, and are probably related to older hot springs activity. 

Four spring orifices emit water at 157 °F in the early 

summer and 163 °F in the autumn after the flow rate decreases. Visual observations indicate that the flow of each 

hot spring is about 10 gallons per minute. The springs are 

bubbling, and the escaping gases have a faint odor of sulfur. The temperature of the water is high enough to permit 

direct use for domestic heating, but the flow rate is small. 

Drilling and development could increase the rate of energy 

production. In this report, however, the geothermal area is 

classified as an occurrence. 

Oil and Gas 

Traces of oil at the hot springs are indicated by thin, 

discontinuous, coalescing, iridescent films (see Emmons, 

E6 Mineral Resources of Wilderness Study Areas: East-Central Oregon 
1921, p. 24). Four samples of rocks were collected near the 

springs from two high-angle faults that could have acted as 

conduits, but they contain no detectable hydrocarbons (0.05 

percent lower limit of detection). Other samples of rock 

from vertical fault zones throughout the study area also 

tested negative for soluble hydrocarbons (see Emmons, 1921, 

p. 28). Bubbles rising at the hot springs were not flammable. Source of the oil trace was not identified. The oil at 

the the hot springs could be contamination from petroleum 

products used during road construction in the recent past or 

from automobile engine oil that may wash off the highway 

during sporadic heavy rains. 

Recommendations for Further Study 

Additional geologic mapping, geochemical sampling, 

and geophysical studies are needed to further evaluate gold 

occurrences at three sites in and near the study area: the 

Gold Creek 1-34 claim group, the Treasure 1-4 claim group, 

and along Simmons Gulch. Drilling the quartz-vein system 

in the Gold Creek 1-34 claim group might detect gold 

sources at depth. 

Mining costs, beneficiation methods, and markets for 

specific applications should be studied before attempting to 

mine diatomite, basalt, stone, and (or) sand and gravel, and 

detailed sampling would be needed before mining diatomite. 

More detailed geologic mapping is recommended to find 

the source of perlite boulders in Simmons Gulch. In-place 

perlite occurrences may have economic value. 

Testing of the hot springs area is recommended to 

determine geothermal reservoir characteristics. In order to 

evaluate the occurrence of geothermal energy that is known 

to be present in the Gold Creek Wilderness Study Area and 

to identify geothermal energy resources, instrument measurements of flow and variation in flow as well as variations 

in temperature must be made. 

ASSESSMENT OF MINERAL RESOURCE 

POTENTIAL 

By james G. Evans, james G. Frisken, Andrew Griscom, and 

Don L. Sawatzky 

U.S. Geological Survey 

Geology 

The Gold Creek and Sperry Creek Wilderness Study 

Areas are underlain by a flat-lying sequence of Miocene 

through Holocene sedimentary, volcanic, and pyroclaslic 

rocks (fig. 2). The following rock descriptions combine field 

observations made during the present study and rock descriptions from Hagood (1963), Kittleman and others (1965), 

and Haddock (1967). 

The oldest rock unit in the study area consists mostly 

of alternating layers of aphanitic and porphyritic basalt and 

basalt flow breccia, herein called the basaltic complex; it is 

equivalent to the unnamed igneous complex of Kittleman 

and others (1965). As much as 10 percent of the unit consists of sandstone, siltstone, red welded basaltic tuff, and 

hyaloclastite beds as thick as 40 ft. The hyaloclastite consists of angular vesicular basalt fragments and pale-brown 

silt. Some of the porphyritic basalt contains plagioclase 

phenocrysts as long as 1 in. According to Hagood (1963), 

the basalt is composed of labradorite and clinopyroxene, as 

the major constituents, and minor opaque iron oxide, glass, 

olivine, and alteration products. Kittleman and others (1965) 

estimated the maximum thickness of the unit to be 2,000 ft 

in Malheur Canyon. 

The Dinner Creek Welded Ash-Flow Tuff (Kittleman 

and others, 1965) is a rhyolitic ash-flow tuff that 

stratigraphically overlies the basaltic complex but is commonly absent in the study area. The most conspicuous part 

of this unit is a cliff-forming, light-brown, densely welded 

tuff that is partly devitrified, contains lithophysae as much 

as 1 in. across, and contains phenocrysts (plagioclase, 

anorthoclase, hypersthene) and lithic fragments (pumice, 

basalt) as long as 4 in. Unwelded to partly welded horizons 

occur above and below the strongly welded part. The total 

thickness of the unit varies, but the maximum is 80 ft; 

commonly only about 20ft or less of the strongly welded 

tuff is visible. On the basis of isopachs of the tuff, which 

indicate an increasing thickness of the unit to the northwest, 

Haddock (1967) suggested that the tuff was extruded from 

a silicic vent at Castle Rock, 24 mi northwest of the study 

area. 

The Hunter Creek Basalt (Kittleman and others, 1965) 

overlies the Dinner Creek Welded Ash-Flow Tuff and the 

basaltic complex where the Dinner Creek is absent. The 

Hunter Creek is a black, fine-grained and aphanitic basalt 

that typically breaks into irregular angular fragments about 

8 in. across. Hagood (1963) identified labradorite, 

clinopyroxene, and glass as the major constituents and minor opaque iron oxide. 

The Littlefield Rhyolite (Kittleman and others, 1965), 

overlying the Hunter Creek Basalt, is a gray, porphyritic, 

generally flow-foliated rhyolite that usually weathers to thin 

plates and has a brown oxide patina on the weathered surfaces. The lowermost part of the unit locally consists of 10 

to 20ft of partly welded tuff or unconsolidated tuffaceous 

siltstone and sandstone, which is usually succeeded by a 

zone of black vitrophyre of varied thickness. The unit also 

contains obsidian, scoriaceous zones possibly related to flow 

margins, and black perlitic vitrophyre autointrusions. In 

places, the unit contains beds of white to pale-brown lithic 

tuff as much as 40 ft thick that clearly separate flows in the 

unit. As much as 4 percent of the typical rhyolite consists 

of sanidine, andesine, orthoclase, clinopyroxene, hypersthene, and magnetite phenocrysts as long as 0.0625 in. in a 

Mineral Resources of the Gold Creek and Sperry Creek Wilderness Study Areas, Malheur County, Oregon E7 
EXPLANATION 

Area having high mineral resource potential (H) 

D Area having moderate mineral resource potential (M) 

D Area having low mineral resource potential (L) 

Level of certainty of assessment 

B Data only suggest level of potential 

Area having identified mineral resources for commodities 

as labeled 

Commodities 

Au 

Ag 

Dia 

Geo 

Hg 

0/G 

Sto 

S !G 

Gold 

Silver 

Diatomite 

Geothermal resources 

Mercury 

Oil and gas 

Building and decorative stone 

Sand and Gravel 

Geologic map units 

Oa Alluvium (Quaternary) 

Ols Landslide deposits (Quaternary) 

OTf Fanglomerate (Quaternary and Pliocene) 

Tts Tuff and tuffaceous siltstone (Pliocene or Miocene) 

Ttp Tims Peak Basalt ofKittleman and others (1965) 

(Miocene) 

Tbb Pillow-basalt breccia (Miocene) 

Tl Littlefield Rhyolite of Kittleman and others (1965) 

(Miocene) 

Th Hunter Creek Basalt of Kittleman and others (1965) 

(Miocene) 

Td Dinner Creek Welded Ash-Flow Tuff of Kittleman and 

others (1965) (Miocene) 

Tb Basaltic complex (Miocene or older}--Equivalent to 

unnamed igneous complex of Kittleman and others 

(1965) 

Contact 

·\&fM;'§;;)-)c))~B·f~,<:J. --.--.. Fault-Dotted where concealed. Bar and ball on 

downthrown side 

Figure 2. Mineral resource potential, identified mineral resources, and generalized geologic map of Gold Creek and 

Sperry Creek Wilderness Study Areas, Malheur County, Oregon. 

Base from U.S. Geological Survey 1 :24,000, Monument Peak, 

Tims Peak, 1972; jonesboro, Namorf, South Mtn., 1990. Con-

·;------':::___ __ "#'_-f<;;,,~··---i!f---?--\;-··~~~~~'-7-A~~lf+""7"'"'---d--"--::..,..---t>L..._·,,-~;~L.L+~44 tour intervals 40 and 20ft. Geology mapped by j.G. Evans, 

1988. 

E9 
glassy matrix that is locally devitrified and, in places, contains abundant spherulites as much as 0.5 in. across. The 

rhyolite has a minimum thickness of 250 ft along the west 

boundary of the study area and thickens eastward to at least 

880 ft in the northeastern part of the Gold Creek Wilderness Study Area, where it rests on progressively older rocks 

that locally include the basaltic complex. Most of the transition of the underlying units from the Hunter Creek Basalt to 

the basaltic complex is concealed beneath landslides. The 

Littlefield Rhyolite thickens to at least 1,200 ft (maximum 

exposed thickness, base not exposed) in upper Simmons 

Gulch in the area of an aeromagnetic high (fig. 3). The high 

may reflect the presence of a circular rhyolite vent that may 

be as wide as 4 mi through which the rhyolite was extruded. 

A pillow-basalt breccia, which overlies most of the 

Littlefield Rhyolite, consists of pyroclastic and flow fragments of basalt as much as 5 ft across and includes at least 

one minor unbrecciated flow at its base. The matrix of the 

breccia locally makes up more than half the unit and appears to be largely black and yellowish basaltic glass although some silt is present. The pillows and the shattered, 

partly altered basaltic glass suggest interaction of basalt 

flows and water, possibly in a lake. Hagood (1963) identified labradorite and glass, as major constituents, and minor 

pyroxene (augite and hypersthene) and olivine. The unit is 

as thick as 400 ft in the south-central part of the study area 

and pinches out in places in the western part. 

The Tims Peak Basalt (Kittleman and others, 1965) 

overlies the pillow-basalt breccia and forms most of the top 

of the plateau in the southern part of the study area. The 

basalt is dark-gray to black, vesicular, and diktytaxitic, and 

it forms cliffs showing moderately well developed columnar jointing. Hagood (1963) identified labradorite, 

clinopyroxene, and olivine as major constituents and minor 

glass and opaque iron oxide. The maximum thickness in the 

study area is 200 ft. 

A unit of white and pale-gray tuff and tuffaceous 

siltstone, apparently deposited in a lake, overlies part of the 

Littlefield Rhyolite near the east boundary of the Gold Creek 

Wilderness Study Area. These lake beds are as much as 

250 ft thick in the study area and are continuous with the 

thicker sequence of lake beds (fig. 1) that Kittleman and 

others (1965) named the Bully Creek Formation in the 

Harper area just east of the study area. 

Ages of the units described above range from Miocene to presumably early Pliocene. Fossil data suggest that 

most of the section is late Miocene or older in age (Hagood, 

1963; Kittleman and others, 1965). Three radiometric ages 

from the Dinner Creek Welded Ash-Flow Tuff, as determined by Fiebelkorn and others (1983), suggest that the 

tuff is middle Miocene in age. If these radiometric ages are 

correct, the age of the basaltic complex (the unnamed igneous complex of Kittleman and others, 1965) is middle Miocene or older, and the overall range for the Hunter Creek 

Basalt through the Tims Peak Basalt is middle Miocene and 

possibly younger. The suggestion of Kittleman and others 

(1965) that the Tims Peak Basalt may be early Pliocene in 

age is consistent with this interpretation. However, radiometric ages listed by Fiebelkorn and others (1983) for the 

Littlefield Rhyolite and Tims Peak Basalt are older (early 

Miocene) than the geologic ages discussed above for these 

units in the study area. It is likely that the samples of the 

Littlefield Rhyolite and Tims Peak Basalt that were dated 

may have been subjected to weak epithermal alteration that 

altered the initial isotope ratios. Unpublished mapping by 

Evans in the Tims Peak quadrangle, southeast of the study 

area, suggests that the Tims Peak Basalt correlates with the 

Shumuray Ranch Basalt of Kittleman and others (1965), 

which was dated as middle Miocene in age by Fiebelkorn 

and others (1983). The age of the Bully Creek Formation is 

not known, but, on the basis of unpublished mapping by 

Evans southeast of the study area, it is likely to be older 

than the Tims Peak Basalt. 

Pliocene and Quaternary fanglomerate covers 6 mil 

of the northern part of the study area, extends from the 

Malheur River to an elevation of 4,200 ft, and is as much as 

200 ft thick. 

Most of the Holocene landslide deposits, some with 

areas of as much as 1 mil, are associated with the lower 

contact of the Littlefield Rhyolite and are especially widespread where the rhyolite is thickest in the eastern part of 

the Gold Creek Wilderness Study Area. Some landslides 

occur along faults. 

Minor Holocene alluvium occurs at the mouth of Gold 

Creek. 

Steep faults that strike north, northwest, and northeast 

in the study area cut flat-lying and gently dipping units that 

dip generally northward toward the Malheur River. Vertical 

displacements are as much as 500 ft. The steep north-striking 

faults near the east boundary of the Gold Creek Wilderness 

Study Area may be part of a major fault zone. 

Geochemical Studies 

The U.S. Geological Survey collected 42 minus-80-

mesh stream-sediment samples, 37 concentrate samples 

panned from stream sediments, 69 rock samples, and 1 hotspring water sample from the Gold Creek and Sperry Creek 

Wilderness Study Areas in 1988. The stream-sediment 

samples reflect bedrock geochemistry and can indicate areas of mineralization. Nonmagnetic heavy-mineral concentrate prepared from a panned concentrate may be useful for 

detecting minerals associated with mineralization and alteration and is more likely to reveal small or poorly exposed 

mineralized areas. 

All of the samples were analyzed for 35 elements by 

a six-step semiquantitative emission spectrographic method 

described by Crock and others (1987). The nonmagnetic 

heavy-mineral concentrates were also analyzed for platiE10 Mineral Resources of Wilderness Study Areas: East-Central Oregon 
num and palladium. The stream-sediment and rock samples 

were analyzed for mercury by an atomic absorption method, 

for antimony, arsenic, bismuth, cadmium, and zinc by an 

inductively coupled argon plasma-atomic absorption method 

described in Crock and others (1987), and for gold by a 

graphite-furnace atomi~ absorption method described by 

Meier (1980). Because the graphite-furnace method does 

not decompose the silicate minerals in the sample, the gold 

values obtained are assumed to be due to mineralization 

and not to background levels of gold in the sample. The 

stream-sediment samples were analyzed for uranium by the 

Centanni ultraviolet fluorescence method described by 

O'Leary and Meier (1986, p. 42-44). Four nonmagnetic 

heavy-mineral-concentrate samples yielding high tin and 

beryllium concentration were analyzed for fluorine by an 

ion-selective electrode method described by O'Leary and 

Meier (1986, p. 21-23). 

The thresholds for anomalous concentrations of elements in rock and stream-sediment samples were calculated 

at two to three times the arithmetic means of element concentrations in local basalts. When the mode was below the 

lower level of detection for an element, the lower level of 

detection was assigned as threshold value. The thresholds 

for anomalous values of elements in nonmagnetic heavymineral concentrates were chosen from previous experience 

with this sample medium. 

Gray and others (1983) and Bukofski and others 

(1984) reported silver and arsenic anomalies from Simmons 

Gulch in the northeastern part of the Gold Creek Wilderness Study Area and silver, lead, and copper anomalies 

from Spring Creek in the northwestern part of the Gold 

Creek Wilderness Study Area (fig. 2). Those geochemical 

anomalies and the U.S. Geological Survey samples having 

anomalous elements in this study suggest that the northern 

part of the Gold Creek Wilderness Study Area, including 

the Simmons Gulch and Spring Creek areas, and the eastern 

part of the Sperry Creek Wilderness Study Area were subjected to hot-spring-type epithermal mineralization. The area 

of most intense mineralization is indicated by ore-related 

minerals in the concentrate samples. All of the antimony, 

arsenic, cadmium, gold, and silver anomalies and the highest boron, cadmium, lead, molybdenum, strontium, tungsten, 

and zinc anomalies occur in the northern part of the Gold 

Creek Wilderness Study Area (Malcolm and others, 1990). 

This is also the area in which quartz and calcite veins are 

present. Gold was detected (0.002-0.1 ppm) in 13 rock 

samples from this area. 

Silica carbonate sinter is being deposited at a presentday hot spring area along the north boundary of the Gold 

Creek Wilderness Study Area. The highest concentrations 

of mercury (more than 36 ppm), arsenic (7 ,000 ppm), antimony (370 ppm), tungsten (50 ppm), strontium (more than 

5,000 ppm), and beryllium (10 ppm) from samples of sinter 

and black mud at the springs are anomalous. Some of these 

samples contain as much as 0.002 ppm gold. Cinnabar was 

. identified in a concentrate sample collected from the hot 

spring; this sample also contains 4 percent fluorine, which 

·suggests the presence of fluorite. The mineralization associated with this hot spring is similar to that which produced 

the silicification and geochemical anomalies in the northern 

part of the Gold Creek Wilderness Study Area. 

About 0.3 mi south of and 400 ft above the hot spring 

area, a vertical northwest-striking, 2- to 3-ft-thick hydrothermally brecciated and hydrothermally recemented quartz 

vein cuts through basalt for at least 0.3 mi. Rock samples 

show anomalous values of gold as high as 0.045 ppm in the 

quartz and 0.1 ppm in nearby basalt. (Greater values were 

found in samples taken in this area by the U.S. Bureau of 

Mines.) The highest values for silver (3 ppm), mercury (more 

than 36 ppm), molybdenum (1,000 ppm), arsenic (48 ppm) 

and antimony (57 ppm) are also anomalous in these rocks. 

Opal, chalcedony and crystalline quartz were seen in stream 

gravels and as thin veins in basalt at 15 sites across the 

northern part of the study area. Galena, cinnabar, barite, 

and celestite were identified in the panned concentrates from 

the area of Gold Creek. Molybdenite was identified in 

panned concentrates from tributaries of lower Simmons 

Gulch. No native gold was seen during microscopic examination of the panned concentrates, but gold was detected in 

two stream-sediment samples (0.09 and 0.006 ppm) from 

small tributaries of lower Simmons Gulch (sees. 11 and 12, 

T. 21 S., R 40 E.). The panned concentrate from the tributary 

yielding 0.006 ppm gold also contains 5 ppm silver, 3,000 

ppm molybdenum, 50 ppm beryllium, and 150 ppm tin. 

Shotgun shells were noted in the study area, and lead 

fragments were seen in one concentrate. Therefore, some of 

the lead and possibly some associated antimony may be 

due to this contaminant. However, galena that was identified in one panned concentrate and antimony anomalies in 

rock samples demonstrate that lead and antimony are also 

clearly related to the epithermal mineralization. 

Anomalous beryllium and tin concentrations in many 

of the panned concentrates appear to come from the 

Littlefield Rhyolite. Anomalous thorium, yttrium, and lanthanum concentrations also occur in association with the 

Littlefield Rhyolite in the Simmons Gulch area. Four panned 

concentrate samples that have relatively high beryllium (10 

to 30 ppm) and tin (700 to 1,500 ppm) values were analyzed for fluorine, an element usually associated with beryllium and uranium in fluorite-related beryllium deposits 

(Griffitts, 1982). The fluorine values range from 1,000 to 

2,500 ppm, which are one to three times the average fluorine 

concentration in most rhyolites and, therefore, are not considered anomalous. Because fluorine concentrations in the 

panned-concentrate samples and uranium concentrations in 

all the stream-sediment samples are not anomalous, economic beryllium-fluorine-uranium deposits are unlikely in 

the study area. Rhyolite-hosted tin deposits (Reed and others, 

1986) occur as cassiterite in discontinuous veinlets in rhyolite flow or dome complexes· and in placers derived from 

Mineral Resources of the Gold Creek and Sperry Creek Wilderness Study Areas, Malheur County, Oregon E11 
them, and they may have associated fluorine minerals (fluorite and topaz). Although a rhyolite dome may be present in 

the southeastern part of the Gold Creek Wilderness Study 

Area, the scattered grains of beryllium-, lanthanum-, tin-, 

thorium-, and yttrium-bearing minerals in the Littlefield 

Rhyolite are the most likely sources of these anomalies, and 

ore-grade concentrations of these minerals are unlikely in 

the study area. 

Anomalous concentrations of nickel, chromium, vanadium, and manganese in many of the panned concentrates are probably derived from isomorphous substitution 

of these elements in mafic minerals weathered from basalt. 

Mafic minerals make up as much as 90 percent of some 

panned concentrates after the initial magnetic separation. 

Additional removal of mafic minerals was not attempted 

because of the small quantity of sample remaining after the 

initial magnetic separation. Nickel, chromium, and vanadium concentrations correlate well with one another and 

probably come from a single source, the basalt in the study 

area. Manganese anomalies are more widespread, and some 

are related to the epithermal mineralization. For example, 

one sample of calcite-vein material from basalt in the Gold 

Creek drainage contains more than 5,000 ppm manganese. 

Ore-grade chromium, nickel, vanadium, or manganese deposits are not likely in the geologic environment of the 

study area. 

Geophysical Studies 

An aeromagnetic survey that includes the Gold Creek 

and Sperry Creek Wilderness Study Areas was flown in 

1976 and 1977 by the Geophysics Group at Oregon State 

University as part of a study of the Vale-Owyhee geothermal area (Boler, 1978). The aeromagnetic data were collected 

along parallel east-west flightlines spaced 1.0 mi apart at a 

constant flight elevation of 7,000 ft above sea level. The 

Earth's main field was subtracted from the data which were 

then plotted by machine and hand contoured at a scale of 

1:62,500. The final residual map was drafted at a scale of 

1:125,000. 

Additional aeromagnetic data are available in the atlas of the Boise quadrangle (scale 1 :500,000) published for 

the Department of Energy (geoMetries, Inc., 1979). These 

data were collected during east-west helicopter flights at an 

average height of 400 ft above ground and a profile spacing 

of 3 mi. Two of these profiles cross the wilderness study 

area. 

Variations in the Earth's magnetic field on an aeromagnetic residual map are usually caused by variations in 

the amounts of magnetic minerals in different rock units; 

magnetite is the common magnetic mineral in this area. 

Magnetic minerals, where locally either concentrated or absent, may cause a high or low magnetic anomaly that can 

be a guide to mineral occurrences or deposits. Boundaries 

between magnetic and relatively less magnetic rock units 

are located approximately at the steepest gradient on the 

flanks of the magnetic anomaly because at these magnetic 

latitudes the inclination of the Earth's main magnetic field 

is relatively steep (68° below the horizontal). 

Because of the preponderance of lava flows and other 

volcanic rocks in this area, one might expect that the majority of the anomalies are caused by volcanic rocks. However, the survey aircraft was generally more than 2,000 ft 

above the surface of the ground in this area, a distance great 

enough to suppress most of the short-wavelength anomalies 

generated by the rocks at or near the surface. The contoured 

magnetic map (fig. 3) shows a broad subcircular magnetic 

high about 4 mi in diameter and about 400 gammas in 

amplitude that is centered on the southeast boundary of the 

Gold Creek Wilderness Study Area and extends 3 mi to the 

northwest, about halfway across the study area. Because of 

its great width and form, the high represents a causative 

Figure 3. Total-field aeromagnetic anomaly map of region including Gold Creek (GC) and Sperry Creek (SC) Wilderness 

Study Areas (bold outlines), Malheur County, Oregon. Contour 

interval 50 gammas; hachures indicate closed areas of lower 

values. 

E12 Mineral Resources of Wilderness Study Areas: East-Central Oregon 
rock mass at least 5,000 ft thick which may be an intrusion 

into the basaltic complex (the unnamed igneous complex) 

that forms the volcanic basement in this area (Kittleman 

and others, 1967). The causative mass and the magnetic 

high appear to be terminated on the east by the major northsouth fault near the east boundary of the Gold Creek Wilderness Study Area. Geologic relations interpreted by Evans 

suggest that the aeromagnetic high reflects the buried vent 

through which the Littlefield Rhyolite of Kittleman and 

others (1965) was extruded into the study area. The economic potential of this possible rhyolite vent is unknown. 

Another major magnetic feature is a distinctive northeast-trending magnetic low, about 6 mi long by 3 mi wide, 

located 1 mi southwest of the southwest border of the Gold 

Creek Wilderness Study Area. This anomaly is about 400 

gammas in amplitude and correlates well with an uplifted 

part of the basaltic complex. Two intrusive rhyolite plugs 

centered within this oval area display intense local magnetic lows having amplitudes of more than 1,500 gammas 

at an altitude of 300ft above the ground (geoMetries, Inc., 

1979). The lows are caused by reverse remanent magnetization, certainly in the rhyolite plugs and perhaps also in the 

uplifted basaltic complex; another reasonable possible cause 

is a large concealed shallow-deP.th siliceous pluton related 

to the plugs and to the doming. The absence of significant 

rock alteration in this area suggests that these observations 

have little, if any, economic significance. 

A gravity survey of this same region has been described and interpreted in a thesis by Lillie (1977). The 

average station spacing is about 5 mi, and 15 gravity stations are located within or near the study area. The data are 

presented as a complete Bouguer gravity anomaly map having a contour interval of 2 milligals and a reduction density 

of 2.67 grams per cubic centimeter. Over most of the study 

area the gravity field is relatively featureless. A linear gravity gradient that trends north-south and slopes down to the 

west along the east border of the Gold Creek Wilderness 

Study Area is probably associated with the north-south fault 

on the east side of the study area. Most of this gravity 

feature is outside the study area and probably has no economic significance, although thermal springs and wells are 

associated with major north-south faults in the Vale Known 

Geothermal Resource Area 45 mi to the northeast. 

A small gravity low 3 mi in diameter probably extends into the north end of the Sperry Creek Wilderness 

Study Area. This low may be in part associated with a local 

small magnetic low. The source of these two associated 

features is not explained but, on the basis of interpretation 

of marginal gradients, must be very shallow. These gravity 

data and features probably do not indicate any resources of 

economic value. 

Aerial gamma-ray spectrometer measurements are 

available along 3-mi-spaced profiles illustrated in 

geoMetries, Inc. (1979). Results indicate that no statistically significant anomalies for uranium, potassium, and 

thorium occur within the study area. A few uranium anomalies are located outside the study area but within 2 mi of the 

boundary. Examination of the relation between these 

anomalies and the geologic map (Kittleman and others, 1967) 

shows that the anomalies appear to be associated with rocks 

of the Littlefield Rhyolite of Kittleman and others (1965). 

The anomalies indicate that these rocks probably contain 

the largest amounts of uranium, potassium, and thorium in 

this part of the study area; however, these amounts are 

probably within the normal ranges for this type of igneous 

rock and thus do not indicate any resources of economic 

value. 

Linear features in Landsat multispectral scanner (MSS) 

images at a scale of 1:800,000 were mapped by photogeologic interpretation for the region of southeastern Oregon, 

and trend concentration maps were made as a part of the 

present study. Linear features are the topographic and spectral expression of rock fracture patterns and other structural 

and lithologic lineaments. This expression can be enhanced 

or subdued by scanner resolution, sun orientation, atmospheric phenomena, and vegetation. Analysis of linear features in conjunction with geologic and geophysical maps 

may reveal new relationships such as fracture control of 

mineralization. 

Linear features of every orientation are well expressed 

on the surface in southeastern Oregon, except in terrains 

underlain by volcanic rocks. The study area is underlain by 

volcanic rocks that do not show well-developed linear features at the scale of 1:800,000. 

Mineral and Energy Resource Potential 

Geologic and geochemical data suggest that part of 

the north-central part of the Gold Creek Wilderness Study 

Area has a high mineral resource potential for gold, certainty level B, near the mouth of Gold Creek (fig. 2). This 

level of potential is suggested by the amount of gold detected in samples from the northwest-striking quartz-vein 

system and the adjacent basalt wall rock. The certainty level 

B is assigned because the surficial geochemical data point 

to only the possibility, rather than the probability, of gold 

mineralization at depth. 

Geologic, geochemical, and geophysical data suggest 

that the northern part of the Gold Creek Wilderness Study 

Area and the eastern part of the Sperry Creek Wilderness 

Study Area have moderate mineral resource potential for 

gold, silver, and mercury, certainty level B (fig. 2). This 

estimate of potential is based on the occurrences of these 

three metals in anomalous concentrations in the rock, streamsediment, and panned-concentrate samples from the study 

area and their association with several other elements commonly associated with hot-spring epithermal deposits. These 

occurrences, and the northwest-striking quartz-vein system, 

may be related to present and past hot springs along the 

Mineral Resources of the Gold Creek and Sperry Creek Wilderness Study Areas, Malheur County, Oregon E13 
north boundary of the Gold Creek Wilderness Study Area 

(fig. 2). The certainty level B is assigned because it seems 

likely that the hot-spring system results from deeply circulating meteoric waters in a complex fault zone along the 

Malheur River canyon just north of the study area (Evans, 

unpub. mapping, 1989) and because it is not clear that economic gold, silver, and mercury deposits occur at depth. 

Fouch (1983) estimated that the oil and gas resource 

potential of the study area is zero to low. Miller (1989) 

reported possible oil slicks at the hot springs, but these can 

be explained as contamination from spillage of petroleum 

products on the nearby highway. The likelihood of occurrences of oil and gas within the study area is low to remote. 

Therefore, for the purpose of this report, the entire study 

area is considered to have low energy resource potential for 

oil and gas, certainty level B. 

A small area along the north boundary of the Gold 

Creek Wilderness Study Area has a low resource potential 

for geothermal energy, certainty level B (fig. 2). Measurements by the U.S. Bureau of Mines (Miller, 1989) indicate 

that the water temperature in four orifices exceeds 150 °F and 

that the combined flow rate is about 40 gallons per minute. 

Development could increase the flow rate or energy production. The likelihood of production of enough geothermal 

energy to constitute a resource is low, although the available 

information only suggests this level of resource potential. 

REFERENCES CITED 

Benjamin, D.A., and Gale, George, 1984, MLA costing procedures 

for classification of mineral resources: U.S. Bureau of Mines, 

Western Field Operations Center, Spokane, Wash., Open-File 

Report, 60 p.; includes computer program. 

Beikman H.M., Hinkle, M.E., Frieders, Twila, Marcus, S.M., and 

Edward, J.R.,1983, Mineral surveys by the Geological Survey 

and Bureau of Mines of Bureau of Land Management wilderness study areas: U.S. Geological Survey Circular 901,28 p. 

Boler, P.M., 1978, Aeromagnetic measurements, magnetic source 

depths, and the Curie point isotherm in the Vale-Owyhee, 

Oregon, geothermal area: Corvallis, Oregon State University 

M.S. thesis, 104 p. 

Bukofski, J.F., Lovell, J.S., and Meyer, W.T., 1984, Mineral resource assessment through geochemical studies of heavymineral concentrates from wilderness study areas in the Burns, 

Prineville, and Vale districts, southeastern Oregon: Barringer 

Resources, Inc., prepared for U.S. Bureau of Land Management, Oregon State Office, Portland, 94 p. 

Crock, J.G., Briggs, P.H., Jackson, L.L., and Lichte, F.E., 1987, 

Analytical methods for the analysis of stream sediments and 

rocks from wilderness study areas: U.S. Geological Survey 

Open-File Report 87-84,35 p. 

Edmund, R.L., 1989, Annual reference catalog for optics, 

science, and education: Barington, N.J., Edmund Scientific 

Company, 163 p. 

Emmons, W.H., 1921, Geology of petroleum: New York, McGrawHill, 610 p. 

Ferns, M.L., 1989, Mining activity and exploration in Oregon, 

1988: Oregon Department of Geology and Mining, Oregon 

. Geology, v. 51, no. 2, p. 27-32. 

Fiebelkorn, R.B., Walker, G.W., MacLeod, N.S., McKee, E.H., 

and Smith, J.G., 1983, Index to K-Ar determinations for the 

State of Oregon: Isochron/W est, no. 37, p. ~. 

Fouch, T.D., 1983, Petroleum potential of wilderness lands in 

Oregon: U.S. Geological Survey Circular 902-J, 5 p. 

geoMetries, Inc., 1979, Aerial gamma ray and magnetic survey, 

Idaho Project, Boise [ 1 o by 2°] quadrangle, Oregon/Idaho: 

Grand Junction, Colo., U.S. Department of Energy, National 

Uranium Resource Evaluation Program, GJBX-10(80), variously paginated. 

Goudarzi, G.H., 1984, Guide to preparation of mineral survey 

reports on public lands: U.S. Geological Survey Open-File 

Report 84-787,51 p. 

Gray, J.J., Peterson, N.N., Clayton, Janine, Baxter, Gary, 1983, 

Geology and mineral resources of 18 wilderness study areas, 

Harney and Malheur Counties, Oregon: Oregon Department 

of Geology and Mineral Industries Open-File Report 0-83-2, 

BLM Contract no. YA-553-CTI-1086, 108 p. 

Griffitts, W.R., 1982, Diagnostic features of fluoride-related beryllium deposits, in Characteristics of mineral deposit occurrences: U.S. Geological Survey Open-File Report 82~795, 

p. 55-59. 

Haddock, G.H., 1967, The Pinner Creek Welded Ash-Flow Tuff 

of the Malheur Gorge area, Malheur Cmmty, Oregon: Eugene, 

University of Oregon Ph.D. dissertation, 111 p. 

Hagood, A.R., 1963, Geology of the Monument Peak area, Malheur 

County, Oregon: Eugene, University of Oregon M.S. 

thesis, 165p. 

Hughes, H.H., 1941, Iceland spar and optical fluorite: U.S. Bureau 

of Mines Information Circular 6468R, 19 p. 

Kittleman, L.R., Green A.R., Haddock, G.H., Hagood, A.R., Johnson, A.M., McMurray, J.M., Russell, R.G., and Weeden, D.A., 

1967, Geologic map of the Owyhee region, Malheur County, 

Oregon: Eugene, University of Oregon, Museum of Natural 

History Bulletin 8, scale 1:125,000. 

Kittleman, L.R., Green, A.R., Hagood, A.R., Johnson, A.M., 

McMurray, J.M., Russell, R.G., and Weeden, D.A., 1965, 

Cenozoic stratigraphy of the Owyhee region, southeastern 

Oregon: Eugene, University of Oregon, Museum of Natural 

History Bulletin 1, 45 p. · 

Lillie, R.J., 1977, Subsurface geologic structure of the Vale, Oregon, Known Geothermal Resource Area from the interpretation of seismic reflection and potential field data: Corvallis, 

Oregon State University M.S. thesis, 52 p. 

Malcolm, M.J., Frisken, J.G., and Motooka, J.M., 1990, Analytical 

results and sample locality map of stream-sediment, heavymineral-concentrate, rock, and water samples for the Gold 

Creek (OR-003-033) and the Sperry Creek (OR-003-035) 

Wilderness Study Areas, Malheur County, Oregon: U.S. 

Geological Survey Open-File Report 90-29,29 p. 

McKelvey, V.E., 1972, Mineral resource estimates and public 

policy: American Scientist, v. 60, p. 32-40. 

Meier, A.L., 1980, Flameless atomic absorption determination of 

gold in geologic materials: Journal of Geochemical Exploration,v. 13,p. 77-85. 

Meisinger, A.C., 1989, Diatomite, in Mineral commodity summaries: U.S. Bureau of Mines, p. 50-51. 

E14 Mineral Resources of Wilderness Study Areas: East-Central Oregon 
~ .. Miller, M.S., 1989, Mineral resources of the Sperry Creek 

Wilderness Study Area and Gold Creek Wilderness Study 

Area and addition: U.S. Bureau of Mines Mineral Land 

Assessment Open-File Report MLA 22-89, 70 p. 

Moore, B.N., 1937, Nonmetallic mineral resources of eastern Oregon: U.S. Geological Survey Bulletin 875, 180 p. 

Norman, James, and Ralston, O.C., 1940, Purification of diatomite 

by froth flotation: American Institute of Mining and Metallurgical Engineers, Technical Publication 1198, 11 p. 

O'Leary, R.M., and Meier, A.L., 1986, Analytical methods used 

in geochemical exploration, 1984: U.S. Geological Survey 

Circular 948,48 p. 

Ramp, Len, 1988, Exploration and mining activity in Oregon, 

1987; Oregon State Department of Geology and Mineral Industries, Oregon Geology, v. 50, no. 4., p. 39-44. 

i{ r·~· · tl - Reea, BL.,~Dhffield, Wendell, Ludington, S.D., Maxwell, C.H., 

and Richter, D.H., 1986, Descriptive model of rhyolite-hosted 

Sn, in Cox, D.P., and Singer, D.A., eds., Mineral deposit 

models: U.S. Geological Survey Bulletin 1693, p. 168. 

Subramanian, R.V., Wang, T.J.W., and Austin, H.F., 1977, Reinforcement of polymers by basalt fibers: Society for the Advancement of Material and Process Engineering, Quarterly, 

v. ~.no. 4, 10 p. 

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

of a resource/reserve classification for minerals: U.S. Geological Survey Circular 831,5 p. 

Walker, G.W., 1977, Geologic map of Oregon east of the 121st 

Meridian: U.S. Geological Survey Miscellaneous Geologic 

Investigations Map I-902, scale 1:500,000. 

Mineral Resources of the Gold Creek and Sperry Creek Wilderness Study Areas, Malheur County, Oregon E1 5 

APPENDIXES 
DEFINITION OF LEVELS OF MINERAL RESOURCE POTENTIAL 

AND CERTAINTY OF ASSESSMENT 

LEVELS OF RESOURCE POTENTIAL 

H HIGH mineral resource potential is assigned to areas where geologic, geochemical, and geophysical characteristics indicate a geologic environment favorable for resource occurrence, where interpretations of data 

indicate a high degree of likelihood for resource accumulation, where data support mineral-deposit models 

indicating presence of resources, and where evidence indicates that mineral concentration has taken place. 

Assignment of high resource potential to an area requires some positive knowledge that mineral-forming processes 

have been active in at least part of the area. 

M MODERATE mineral resource potential is assigned to areas where geologic, geochemical, and geophysical 

characteristics indicate a geologic environment favorable for resource occurrence, where interpretations of data 

indicate reasonable likelihood for resource accumulation, and (or) where an application of mineral-deposit models 

indicates favorable ground for the specified type(s) of deposits. 

L LOW mineral resource potential is assigned to areas where geologic, geochemical, and geophysical characteristics 

define a geologic environment in which the existence of resources is permissive. This broad category embraces 

areas with dispersed but insignificantly mineralized rock, as well as areas with little or no indication of having 

been mineralized. 

N NO mineral resource potential is a category reserved for a specific type of resourt:e in a well-defined area. 

U UNKNOWN mineral resource potential is assigned to areas where information is inadequate to assign a low, 

moderate, or high level of resource potential. 

LEVELS 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 resourt:e potential. 

C Available information gives a good indication of the level of mineral resourt:e potential. 

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

t 

.....J 

< i= 

z 

LLJ 

0 

~ 

LLJ 

u 

0:: 

::) 

0 

V) 

LLJ 

0:: 

u.. 

0 

.....J 

LLJ 

a:; 

.....J 

A 

U/A 

UNKNOWN POTENTIAL 

Abstracted with minor modifications from: 

B c 

H/B H/C 

HIGH POTENTIAL HIGH POTENTIAL 

M/B M/C 

MODERATE POTENTIAL MODERATE POTENTIAL 

UB uc 

LOW POTENTIAL LOW POTENTIAL 

LEVEL OF CERTAINTY ~ 

D 

H/D 

HIGH POTENTIAL 

MID 

MODERATE POTENTIAL 

UD 

LOW POTENTIAL 

N/D 

NO POTENTIAL 

Taylor, R.B., and Steven, T.A., 1983, Definition of mineral resource potential: Economic Geology, v. 78, no. 6, p. 1268-1270. 

Taylor, R.B., Stoneman, R.J., and Marsh, S.P., 1984, An assessment of the mineral resource potential of the San Isabel National Forest, south-central Colorado: U.S. 

Geological Survey Bulletin 1 638, p. 40-42. 

Goudarzi, G.H., compiler, 1984, Guide to preparation of mineral survey reports on public lands: U.S. Geological Survey Open-File Report 84-0787, p. 7, 8. 

E18 Mineral Resources of Wilderness Study Areas: East-Central Oregon 
RESOURCE/RESERVE CLASSIFICATION 

IDENTIFIED RESOURCES UNDISCOVERED RESOURCES 

Demonstrated Probabi I ity Range 

Inferred 

Measured Indicated Hypothetical Speculative 

I Inferred I 

ECONOMIC Reserves 

Reserves 

I I ----~---- !----------- -~-

MARGINALLY Marginal Inferred 

Marginal ECONOMIC Reserves Reserves ____ T I ____ I 1----------- -~-

SUB- Demonstrated Inferred 

Subeconomic Subeconomic 

ECONOMIC Resources Resources I I I 

Major elements of mineral resource classification, excluding reserve base and inferred reserve base. Modified from McKelvey, V.E., 1972, Mineral 

resource estimates and public policy: American Scientist, v. 60, p. 32-40; and U.S. Bureau of Mines and U.S. Geological Survey, 1980, Principles 

of a resource/reserve classification for minerals: U.S. Geological Survey Circular 831, p. 5. 

Mineral Resources of the Gold Creek and Sperry Creek Wilderness Study Areas, Malheur County, Oregon E19 
GEOLOGIC TIME CHART 

Terms and boundary ages used by the U.S. Geological Survey in this report 

EON ERA PERIOD EPOCH 

Holocene 

Quaternary Pleistocene 

Neogene Pliocene 

Cenozoic Sub period Miocene 

Tertiary Paleogene Oligocene 

Subperiod Eocene 

Paleocene 

Cretaceous late 

Early 

late 

Mesozoic Jurassic Middle 

Early 

late 

Triassic Middle 

Early 

Permian late 

Phanerozoic . Early 

late 

Pennsylvanian Middle 

Carboniferous Early Periods 

Mississippian late 

Early 

late 

Devonian Middle 

Paleozoic Early 

late 

Silurian Middle 

Early 

late 

Ordovician Middle 

Early 

late 

Cambrian Middle 

Early 

late Proterozoic 

Proterozoic Middle Proterozoic 

Early Proterozoic 

late Archean 

Archean Middle Archean 

Early Archean 

--------------- - - - - - - - - - - - - - - - - - - - - - - - - - - (38001}- - - - - - - - - - - - - - - - - - -

pre-Archean2 

1Rocks older than 570 Ma also called Precambrian, a time term without specific rank. 21nformal time term without specific rank. 

E20 Mineral Resources of Wilderness Study Areas: East-Central Oregon 

AGE ESTIMATES OF 

BOUNDARIES IN 

MILLION YEARS (Ma) 

0.010 

1.7 

5 

24 

38 

55 

66 

- 96 

138 

205 

-240 

290 

-330 

360 

410 

435 

500 

1

-570 

900 

1600 

2500 

3000 

3400 

4550 
SELECTED SERIES OF U.S. GEOLOGICAL SURVEY PUBLICATIONS 

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GOLD CREEK, SPERRY CREEK WILDERNESS STUDY AREAS