Mineral Resources of theLower Owyhee Canyon Wilderness Study Area, 

Malheur County, Oregon

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Chapter F

Mineral Resources of the

Lower Owyhee Canyon Wilderness Study Area,

Malheur County, Oregon

By JAMES G. EVANS, ROBERT L. TURNER, 

ANDREW GRISCOM, and DON L. SAWATZKY 

U.S. Geological Survey

J. DOUGLAS CAUSEY 

U.S. Bureau of Mines

U.S. GEOLOGICAL SURVEY BULLETIN 1 741

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

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Library of Congress Cataloging-in-Publication Data

Mineral resources of the Lower Owyhee Canyon Wilderness Study Area, 

Malheur County, Oregon / by James G. Evans ... [et al.].

p. cm. (Mineral resources of wilderness study areas eastcentral Oregon : ch. F) (U.S. Geological Survey bulletin : 1741-F)

Includes bibliographical references.

Supt. of Docs, no.: I 19.3: 1741-F

1. Mines and mineral resources Oregon Lower Owyhee Canyon 

Wilderness. 2. Lower Owyhee Canyon Wilderness (Or.) I. Evans, 

James George, 1938- . II. Series. III. Series: U.S. Geological 

Survey bulletin ; 1741-F

QE75.B9 no. 1741-F 557.3 s dc20 90-13955 

[TN24.O7] [553 1 .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 Lower Owyhee Canyon Wilderness Study Area 

(OR-003-110), Malheur County, Oregon.

CONTENTS

Summary Fl 

Abstract Fl 

Character and setting Fl 

Identified resources Fl 

Mineral resource potential Fl 

Introduction Fl

Area description F2 

Previous and present investigations F3 

Appraisal of identified resources F3 

Methods F3 

Mining history F5

Appraisal of commodities examined F5 

Zeolite minerals F5 

Clay F6

Decorative stone F6 

Metallic minerals F7 

Sand and gravel F7 

Other commodities F7 

Assessment of mineral resource potential F7 

Geology F7 

Geochemical studies F8 

Geophysical studies F9 

Mineral and energy resource potential Fl 1 

References cited F12 

Appendixes F15

Definition of levels of mineral resource potential and certainty of assessment F16 

Resource/reserve classification F17 

Geologic time chart F18

FIGURES

1. Index map showing location of Lower Owyhee Canyon Wilderness Study Area, 

Malheur County, Oregon F2

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

geology of Lower Owyhee Canyon Wilderness Study Area, Malheur County, 

Oregon F4

3. Complete Bouguer gravity map of Lower Owyhee Canyon Wilderness Study Area, 

Malheur County, Oregon F10

Contents

Mineral Resources of the

Lower Owyhee Canyon Wilderness Study Area,

Malheur County, Oregon

By James C. Evans, Robert L. Turner, Andrew Griscom, and Don L. Sawatzky 

U.S. Geological Survey

]. Douglas Causey 

U.S. Bureau of Mines

SUMMARY

Abstract

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

the Lower Owyhee Canyon Wilderness Study Area, comprising approximately 73,010 acres, was evaluated for mineral 

resources and mineral resource potential. Throughout this report, "wilderness study area" and "study area" refer to the 

73,010 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 in 

1986 and 1987 to assess the identified mineral resources 

(known) and mineral resource potential (undiscovered) of the 

study area. The study area contains an inferred subeconomic 

resource of 7.7 million short tons (st) of zeolite-bearing rock 

and less than 2,000 st of decorative stone. Sand and gravel 

covers approximately 6 mi2 . The entire study area has low 

mineral resource potential for gold, silver, lead, zinc, antimony, 

and mercury. Northern and central parts of the study area 

have low mineral resource potential for barite. The southern 

two-thirds of the study area has low energy resource potential 

for oil and gas. Central and southern parts of the study area 

have low potential for geothermal energy resources.

Character and Setting

The Lower Owyhee Canyon Wilderness Study Area 

is about 30 mi west of Jordan Valley, Oreg (fig. 1). The 

study area is part of the Owyhee Plateau where a 32-milong segment of the Owyhee River has cut a canyon into a 

broad plateau that includes low hills, mesas, and buttes. 

The canyon is incised as much as 1,960 ft into the plateau. 

The study area is underlain by Miocene, Pliocene, and QuaManuscript approved for publication, July 30, 1990

ternary sedimentary, volcanic, and volcaniclastic rocks and 

deposits (fig. 2; see "Appendixes*' for geologic time chart). 

A few steep faults cut the rocks of the study area.

Identified Resources

The study area contains approximately 7.7 million 

short tons (st) of zeolite (clinoptilolite) resources having an 

ammonia-ion exchange capacity (AEC) as high as 2.00 

milliequivalents per gram (meq/g) and less than 100 ft of 

overburden in the Chalk Basin-Lambert Rocks area. Decorative stone occurs in Chalk Basin. Sand and gravel covers 

approximately 6 mi2 on the canyon rims. None of these highvolume, low-unit-value commodities are economically exploitable at present because the same commodities are 

available closer to existing markets or railways.

Mineral Resource Potential

The entire study area has low mineral resource potential for gold, silver, lead, zinc, antimony, and mercury. Two 

smaller areas in the northern and the central parts of the 

study area have low mineral resource potential for barite. 

The southern two-thirds of the study area has low energy 

resource potential for oil and gas. Two small areas in the 

central and southern parts of the study area have low potential for geothermal energy resources.

INTRODUCTION

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

Mineral Resources of the Lower Owyhee Canyon Wilderness Study Area, Malheur County, Oregon F1
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 

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 resources by determining geologic units and struc117°45'

tures, possible environments of mineral deposition, presence of geochemical and geophysical anomalies, and applicable 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 Lower Owyhee Canyon Wilderness Study Area 

(OR-003-110) covers 73,010 acres along the Owyhee River

APPROXIMATE BOUNDARY

OF

LOWER OWYHEE CANYON 

WILDERNESS STUDY AREA 

(OR-003-110)

Desert Sunrise 

(Frying Pan) 

A claim group

Figure 1. Index map showing location of Lower Owyhee Canyon Wilderness Study Area, Malheur County, Oregon.

F2 Mineral Resources of Wilderness Study Areas: East-Central Oregon
and adjacent parts of the Owyhee Plateau. The terrain is flat 

to hilly away from the canyon. The plateau rises gradually 

from 3,780 ft at the southern end north of Rome, Oreg., to 

4,800 ft at the northern end north of The Hole in the Ground. 

Over this same distance, the Owyhee River drops from 3,360 

ft at the southern end to 2,840 ft at the northern end. Maximum relief is 1,960 ft at the northern end where the canyon 

is 5 mi wide. The canyon is most spectacular, however, at 

Iron Point, where the gorge is one-half mile wide and 1,400 

ft deep. Sedimentary rocks along the canyon wall consist of 

alternating white, green, and red beds in the Chalk Basin 

and Jackson Hole areas. Most tributaries of the Owyhee 

River are incised as much as several hundred feet. Bogus 

Creek, however, flows over the very young basalt flows of 

Lambert Rocks and descends to the Owyhee River over a 

200-ft-high waterfall. The arid climate supports sagebrush, 

rabbit brush, and sparse native grasses. Riparian areas support mostly grasses, rushes, and sedges. Parts of the study 

area are used for cattle grazing and also support mule deer, 

pronghorn antelope, wild horses, coyotes, and numerous 

species of birds, small mammals, and reptiles, including the 

western diamondback rattlesnake.

Dirt roads and jeep trails follow much of the study 

area boundary. Access to most of the study area is best 

from Rome on U.S. Highway 95. The east side of the study 

area is accessible by crossing the Owyhee River at a ranch 

2 mi north of Rome. The west side of the study area is 

accessible from the gravel road through Rome Cliffs and 

Crooked Creek Ranch. The Hole in the Ground area at the 

northern end can also be reached by dirt roads from U.S. 

Highway 95, 27 mi east of the study area, and by dirt roads 

that intersect the paved highway 14 mi north of Jordan 

Valley and pass through the Jordan Craters area.

Previous and Present Investigations

Reconnaissance geologic mapping of the southern part 

of the study area was published by Walker and Repenning 

(1966) at the scale of 1:250,000, and later, a geologic map 

that included all of the study area was published by Walker 

(1977) at the scale of 1:500,000. Other workers (Hart, 1982; 

Hart and Mertzman, 1983; Hart and others, 1983) studied 

the stratigraphy and chemistry of the volcanic rocks of 

southeastern Oregon and adjacent regions, including part of 

the Lower Owyhee Canyon Wilderness Study Area. Plumley 

(1986) studied the volcanic stratigraphy and chemistry of 

The Hole in the Ground area. A small part of the geology 

mapped by Plumley was used in preparing figure 2.

Other studies that cover part or all of the study area 

include an evaluation of uranium resources in the southernmost 8 mi of the study area in the Jordan Valley 1° by 2° 

quadrangle (Berry and others, 1981), regional studies of the 

geology and mineral resources (Gray and others, 1983; 

Bukofski and others, 1984), a description of nitrate deposits

(Williams, 1918; Mansfield and Boardman, 1932), and an 

investigation of the ground-water hydrology (Newcomb, 

1961). Zeolite tuffs near Rome (the informal Rome beds) 

immediately south and southwest of the study area and contemporaneous with part of the Miocene sedimentary rock 

section in the study area, were examined by Regis (1967), 

Ellison (1968), Sheppard and Gude (1969, 1974), Munson 

and Sheppard (1974), Sheppard (1976), Campion (1979), 

Sand and Regis (1979), Santini and LeBaron (1982), and 

Mumpton (1983). The mineral resources and geology of the 

Owyhee Breaks Wilderness Study Area, which adjoins the 

Lower Owyhee Canyon Wilderness Study Area on the 

northeast, were studied by Causey (1989b) and Vander 

Meulen and others (1990).

The U.S. Geological Survey carried out field investigations in the study area during 1986 and 1987. This work 

included geologic mapping at the scale of 1:24,000 for later 

compilation at 1:48,000, geochemical sampling, geophysical surveys (gravity and aeromagnetic and gamma-ray spectrometer), and remote sensing. Geochemical data were 

obtained from 58 stream-sediment and 58 heavy-mineralconcentrate samples, and from 68 rock samples (R.L. Turner, 

unpub. data, 1989); 71 rock samples were collected for petrographic analysis.

The U.S. Bureau of Mines conducted field studies 

and examined records of Malheur County, the U.S. Bureau 

of Land Management, and the U.S. Bureau of Mines during 

1986 and 1987. They collected 5 alluvial, 64 rock-chip, and 

7 clay samples.

APPRAISAL OF IDENTIFIED RESOURCES

By]. Douglas Causey 

U.S. Bureau of Mines

Methods

The U.S. Bureau of Mines examined Malheur County 

claim records, and U.S. Bureau of Land Management records 

of mining claim locations, land status, and use. Additional 

information was obtained from the U.S. Bureau of Mines 

library and Mineral Industry Location System.

Five alluvial and bench gravel deposits were sampled. 

The samples consisted of one or two 14-in. level pans full 

of material. Samples were panned to about one-third of 

their initial volume in the field. In the laboratory of the U.S. 

Bureau of Mines, Western Field Operations Center, Spokane, Wash., the samples were weighed, wet-sieved to -14 

mesh, and concentrated on a Wilfley table. Gold was recovered by handpicking and (or) barrel amalgamation, then 

weighed. Concentrates were dried, weighed, and checked 

for radioactivity and fluorescence. The magnetic fraction 

was collected and weighed. Concentrates were examined 

under a binocular microscope to determine if the heavy

Mineral Resources of the Lower Owyhee Canyon Wilderness Study Area, Malheur County, Oregon F3
43' 

15 1

43< 

00'

117°45'

APPROXIMATE BOUNDARY

OF

LOWER OWYHEE CANYON

WILDERNESS STUDY AREA

(OR-003-110)

117°30'

Pb, Sb, Zn -

(entire study area)

A

Wrangle 

Butte

L/BO/G

(southern pan of 

study area) EXPLANATION

| | Area having low mineral resource potential (L) 

Level of certainty of assessment

Data only suggest level of assessment

Data give good indication of level of potential

Area having subeconomic resources of zeolite 

Commodities

Silver Sb Antimony

Gold Zn Zinc

Barium Geo Geothermal resources

Mercury O/G Oil and gas

Lead

Description of map units

Qa Alluvium (Quaternary)

Qls Landslide deposits (Quaternary)

Qb Basalt flows (Quaternary)

QTb Basalt flows (Quaternary and Pliocene)

QTc Conglomerate (Quaternary and Pliocene)

Tbi Basalt and gabbro sills (Pliocene and

Miocene)

Tbs Basalt flows and sedimentary and pyroclastic 

rocks, undivided (Pliocene and 

Miocene) Locally divided into: 

Tb Basalt flows

Ts Sedimentary and pyroclastic rocks 

Tw Welded tuff (Miocene)

 Contact

 Fault Dotted where concealed

X Claim group

A Volcanic vent

F4
minerals ilmenite, garnet, rutile, zircon, or apatite were 

present

A total of 64 rock and 7 clay samples were collected. 

All samples were checked for radioactivity and fluorescence. 

Of these samples, 45 from unsilicified or slightly silicified 

tuff and 6 from clay were subjected to a preliminary zeolite 

test (Helfferich, 1964). The 30 tuff and the 6 clay samples 

that tested positive for the presence of zeolite minerals were 

sent to Cominco American, Spokane, Wash., for X-ray diffraction analysis and to Chemex, Sparks, Nev., for fluorine 

analysis. Ten of the tuff samples that contain zeolite minerals were tested for ammonium-ion exchange capacity (AEC) 

by Rocky Mountain Geochemical Corp., West Jordan, Utah. 

The 19 rock samples that were not tested for zeolites and 

the 15 samples of tuff that did not test positive for zeolite 

were crushed, pulverized, and split at the U.S. Bureau of 

Mines office in Spokane, Wash., and analyzed by Geochemical Service, Inc., Sparks, Nev., for 18 elements.

The six clay samples that contained zeolites have high 

bloating characteristics and white color. These samples were 

examined through X-ray diffraction patterns resulting from 

glycolating and heating them to 300 °C for 1 hr. A clay 

sample that had undergone no other tests was subjected to a 

slow firing and preliminary bloating test performed by the 

University of Alabama, Tuscaloosa, Ala.

Mining History

Most mining and prospecting occurred just south and 

southwest of the study area in the Rome beds, which are 

well exposed near the intersection of the Crooked Creek 

Ranch road and U.S. Highway 95. These rocks have been 

extensively explored and evaluated for fluorite and zeolite 

minerals (mordenite, erionite, clinoptilolite, chabazite, and 

phillipsite) by Kennedy Minerals Co., Union Carbide Corp., 

Shell Development Co., Norton Co., Alcoa Corp., Ernst K. 

Lehman and Associates, Occidental Minerals, Phelps Dodge, 

Northern Minerals Exploration, and Anaconda Minerals Co. 

Some horizons contain more than 90 percent zeolite minerals and others contain more than 16 percent fluorite 

(Mumpton, 1983, p. 43, 46). The U.S. Bureau of Mines, 

Spokane, Wash., has examined these deposits, and the U.S. 

Bureau of Mines, Salt Lake City Research Center, Utah, 

has tested various fluorite-extraction techniques on these 

tuffs.

Mining in the study area between 1961 and 1964 was 

limited to decorative stone at the Frying Pan claim group in 

Chalk Basin. Multicolored silicified tuff was removed at 

that time, but no production was recorded. In 1980 the Desert

"^ Figure 2. Mineral resource potential, identified resources, 

and generalized geology of Lower Owyhee Canyon Wilderness 

Study Area, Malheur County, Oregon.

Sunrise claim group, covering essentially the same area as 

the Frying Pan claims, was located by William Lovan, Sr., 

and William Lovan, Jr., who mined 1- to 3-in.-thick multicolored tuff from a small pit. There is no record of the 

amount of rock mined from these claims, although a few 

tons of stone were reportedly extracted during 1984 and 

1985 (William Lovan, Jr., oral commun., 1986). Evidence 

of additional mining activity was noted when the mine was 

visited in September 1987. It is estimated that less than 200 

st of rock has been mined from these claims.

Natural nitrate salts, which were the main source of 

fixed nitrogen for use in making fertilizer and explosives 

prior to the development of the Haber-Bosch process in 

1913 (Harre and Young, 1983) were reported by Williams 

(1918, p. 286) on the Hercules claim in Owyhee Canyon. 

Claims on an occurrence of soluble nitrate salts about 1 mi 

southwest of Iron Point, near the west end of Bogus Creek, 

were held until 1967 (Malheur County mining claim 

records). In 1943, the U.S. Bureau of Mines examined these 

nitrates and took 10 samples of crystals lining cavities in a 

flow-banded rhyolite (welded tuff?). Analyses of these 

samples show 0.33 to 3.07 percent water-soluble salts, predominantly sodium nitrate (U.S. Bureau of Mines, unpub. 

data, 1943).

Appraisal of Commodities Examined

Zeolite minerals

Samples of tuff, tuffaceous sedimentary rock, and clay 

were collected in the study area to assess the quality of the 

zeolite minerals in them. X-ray diffraction patterns from 

these samples, when compared with patterns published by 

Deer and others (1963, p. 412) and Sheppard and Gude 

(1973, p. 3), show that 29 of the samples contain 

clinoptilolite. Clinoptilolite is used mainly in ion exchange 

applications in aquaculture, agriculture, horticulture, and 

water treatment and for cesium and strontium extraction 

from solutions. It can be used to selectively absorb ammonia from animal wastes, including fish, sewage effluent, and 

gas streams. No other zeolite minerals were identified on 

X-ray diffractometer scans from these samples. Microscopic 

examination indicates that more than 60 percent of some 

samples is a zeolite (James A. Canwell, oral commun., 1988), 

and one sample contains chabazite. The AEC in 10 samples 

containing zeolite ranges from 0.10 to 2.00 milliequivalents 

per gram (meq/g), although there may be an error of as 

much as 20 percent (Causey, unpub. data, 1988).

Of four zones in the study area that were found to 

contain zeolite minerals, only one had been prospected (figs. 

1,2). The lowest zone is about 2 ft thick, covered by 200 to 

300 ft of overburden, and is poorly exposed. The next higher 

zone is also about 2 ft thick, covered by about 300 ft of 

overburden, and is exposed over a distance of about 1,300

Mineral Resources of the Lower Owyhee Canyon Wilderness Study Area, Malheur County, Oregon F5
ft south of Chalk Basin. The third zone is as thick as 25 ft 

and generally covered by less than 100 ft of overburden. In 

the uppermost fourth zone, one of two samples 300 ft apart 

contains zeolite (Causey, 1989a, fig. 3).

The 25-ft-thick zone is an altered, white to yelloworange tuff that contains clinoptilolite. This zone is exposed 

in four outcrops on both sides of the Owyhee River at and 

north of Lambert Rocks. An inferred subeconomic resource 

of 7.7 million short tons (st) of zeolite-bearing rock was 

calculated for three of the outcrops (fig. 2); the fourth outcrop 

is overlain by more than 100 ft of overburden and is not 

considered a resource. The following assumptions were used 

in estimating the tonnage: the thickness of the tuff varies 

uniformly, clinoptilolite is the only zeolite present, the AEC 

is uniform and exceeds 1.00 meq/g, and the specific gravity 

averages 1.45. A specific gravity of 1.45 is equivalent to a 

tonnage factor of 30 cubic feet per st (ft3/st) and is within the 

normal range of 20 to 40 ft3/st for zeolite beds (Eyde, 1981, 

p. 651). A maximum of 100 ft of overburden was used as 

an upper limit of burial for a resource. Planimetric measurements were done on the contour lines on the Lambert 

Rocks 7.5 minute topographic map. The volume of 

overburden was determined by using an approximate integration formula (Simpson's rule; see Selby, 1968, p. 14) on 

the results of planimeter measurements.

An estimated near-surface natural zeolite resource of 

6.7 million st at the largest of these outcrops of zeolitebearing rock was subjected to an economic analysis, using 

the U.S. Bureau of Mines preliminary cost-estimating system (Luis Coppa, written commun., 1988). This analysis, 

using 1987 costs, shows that mine operating costs could be 

less than $113 per st for a 1,000-st-per-day surface mining 

operation at a stripping ratio of 3 to 1. The U.S. Bureau of 

Mines cost-estimating system considers 1,000 st per day to 

be the minimum acceptable mining rate for surface mines. 

Lower mining rates are expected to result in higher pershort-ton mining costs. These costs do not include the costs 

of capital, milling, and marketing industrial minerals. This 

deposit is considered subeconomic because of the remote 

location, varying degree of alteration, lack of information 

on alteration of the tuff below the overburden, color variation 

(not uniformly white), larger more readily available identified 

tonnage of clinoptilolite resources elsewhere in the Western 

United States, and low demand for this zeolite mineral. 

Present information does not indicate any unique character 

that would result in the material from this deposit being 

worth more than, or even as much as, the $125 per st price 

for clinoptilolite reported by Clifton (1987, p. 16). Because 

the deposit is remote and has no known special properties, 

it is not expected to be able to compete with developed 

deposits in the foreseeable future.

A zeolite-bearing clay zone near the Owyhee River 

in Chalk Basin is 2.4 ft thick and is dominantly white bentonite showing less than 5 percent yellow-gray clay bands. 

Dioctahedral smectite (montmorillonite group) and heulandite-group zeolite were identified by using X-ray diffraction. One sample from this zone has an AEC of 2.00 

meq/g, the highest of any of the samples tested. The clay 

zone is believed to be continuous between two exposures 

2,300 ft apart. About 300 ft of poorly lithified tuff, tuffaceous 

sediment, and basalt overlie this clay zone. The deposit 

would be valuable if it were not remote and deeply buried. 

The clay is not amenable to surface mining because of the 

overburden. Underground mining of a 2-ft-thick, horizontal 

bed would not be feasible using current or foreseeable technology. The waste-to-ore ratio would be at least 1 to 1. The 

overlying tuff beds would require extensive support, assuming that the ground could be supported at all. Access 

and haul roads would have to cut through incompetent rocks, 

requiring very frequent maintenance of the roads.

Clay

Another clay zone of unknown thickness is near the 

Desert Sunrise claim group in Chalk Basin. This clay is 

thixotropic and shows popcorn texture on weathered surfaces. Tests of bloating and firing characteristics show that 

the clay could be used for bricks. Firing temperature in the 

range of 1,000 to 1,050 °C produced a brick having Moh's 

hardness of 5 to 6.5, bulk density of 125 Ibs per cubic foot, 

linear shrinkage of 12.5 to 15.0 percent, and porosity of 

13.14 to 22.9 percent. However, bricks are a low-unit-value 

product and the study area is remote from population centers and low-cost transportation. It is not expected that mining of this clay will be feasible.

Decorative Stone

The Desert Sunrise claim group in Chalk Basin has 

small inferred resources of a decorative stone called "picture 

rock," a white chert showing brown hematitic bands. Several 

tons of the platy rock (sheets 1 to 3 in. thick) are exposed in 

a pit 4 ft deep. An unknown amount of this rock, estimated to 

be less than 2,000 st, probably occurs beneath the overburden 

around the pit. On the basis of nearby outcrops, the thickness 

of the decorative stone is estimated to be less than 10 ft. 

Mining on a limited basis (intermittent, small tonnage) can 

be expected to continue at these claims because of their 

high unit value; 1989 retail prices range from $1.25 to $1.75 

per square foot for thin decorative stone. The amount of 

rock mined will depend on activity in the construction 

industry and successful marketing in population centers.

Colored rock less than 500 ft from the Desert Sunrise 

claim group appears to be at the same stratigraphic level as 

the rock at the claims. It differs from the decorative rock at 

the claims in being more massive, breaking less readily into 

thin sheets, and showing dark orange, brown, red, and gray 

colors. The rock may be cut or shaped with hand tools into 

brick-like pieces. Cost of this processing, however, may be 

excessive for most uses.

F6 Mineral Resources of Wilderness Study Areas: East-Central Oregon
Metallic Minerals

No lode gold was found in the study area. There is no 

indication that the study area has deposits of other precious 

or base metals.

A minor amount of gold was found in four of five 

samples of bench gravel and active stream gravel. Estimated value of the gold, in dollars per cubic yard ($/yd3) at a 

gold price of $400 per ounce and a factor of 250 standard 

14-in. pans per cubic yard, is $0.09 to $0.14/yd3 . These data 

do not suggest that economic deposits of placer gold occur 

in the study area.

Sand and Gravel

Sand and gravel occurs on small benches along the 

Owyhee River canyon and on plateau rims south of Lambert Rocks and at the northern end of the study area. The 

rim deposits, volumetrically the most significant ones, underlie about 6 mi2; 4 mi2 of this area is 4 mi south of Lambert Rocks where it attains a maximum thickness of 100 ft. 

No mining of the sand and gravel is expected because the 

deposits are distant from markets. The plateau gravels were 

not tested for gold content; however, because they were 

probably deposited by an ancestral Owyhee River, they are 

not expected to contain any more gold than the samples 

from the active stream and bench gravels.

Other Commodities

The U.S. Bureau of Mines examined nitrate occurrences in the study area in 1943 and found no resources. 

That finding was confirmed during this study. Although the 

present study attempted to locate fluorite in the samples, no 

resources were found.

ASSESSMENT OF MINERAL RESOURCE 

POTENTIAL

By James G. Evans, Robert L. Turner, Andrew Griscom, and

Don L. Sawatzky

U.S. Geological Survey

Geology

The study area is underlain by flat-lying and gently 

dipping volcanic, pyroclastic, and sedimentary rocks and 

deposits of late Miocene to Holocene age (fig. 2). The oldest rock unit of the study area is an unnamed upper Miocene, 

densely welded rhyolitic ash-flow tuff and lithic ash-flow 

tuff. It consists of two cooling units at Iron Point where the 

maximum exposed thickness is 1,200 ft. Much less of it is 

exposed along the Owyhee River to the south in the Chalk 

Basin area and at the south end of the study area. The late

Miocene age is inferred from the interfingering of the upper 

coob'ng unit at Iron Point with upper Miocene sedimentary 

and pyroclastic rocks north of Chalk Basin. On the basis of 

its age and petrographic characteristics, the welded tuff does 

not appear to be related to the middle Miocene Swisher 

Mountain Tuff exposed along the Owyhee River south of 

Rome (Evans, 1987). The thick section of welded tuff at 

Iron Point lies within the deep gravity low (fig. 3) that 

covers most of the northern part of the study area and that 

may reflect a largely buried caldera. This relation suggests 

that the welded tuff at and near Iron Point might be an 

intracaldera facies and that welded tuff south of Iron Point 

is an outflow facies.

Poorly to moderately lithified upper Miocene and 

lower Pliocene sedimentary and pyroclastic rocks interfinger 

with the welded tuff and with basalt flows. This unit includes white, pale-gray, and light-brown siltstone, sandstone, 

conglomerate, bentonitic clays, tuff, welded tuff, chert, 

limestone, and cherty limestone. A maximum uninterrupted 

thickness of 500 ft occurs at Chalk Basin. A lacustrine 

environment during deposition of most of the unit is indicated by the presence of chert and limestone, oolites in the 

limestone, diatom frustules, pelecypod shell fragments, ripple 

marks, and thin cross-bedded horizons. Shrinkage cracks in 

clay-rich siltstone suggest that parts of the basin were subject to periodic desiccation. Vertebrate fossils (horse, beaver, 

and Leparctine) from the unit in and south of Chalk Basin 

are tentatively dated as early Hemphillian or very late 

Clarendonian (9 million years before the present, Ma), or 

late Miocene (C.A. Repenning, written commun., 1987). At 

The Hole in the Ground at the northern end of the study 

area, the unit interfingers with basalt that has yielded an 

early Pliocene age. The distribution of ages suggests that 

the unit south of Iron Point is late Miocene and that much 

of the unit north of Iron Point is early Pliocene. The distribution of sedimentary and pyroclastic rock with respect to 

the possible caldera outlined in figure 3 suggests that the 

thick section exposed in the Chalk Basin area represents 

moat fill around the edge of a caldera and that the thick 

section exposed northeast of Iron Point represents caldera 

fill.

Upper Miocene and lower Pliocene basalt flows overlie and interfinger with the sedimentary and pyroclastic rock 

unit. Uninterrupted outcrops of basalt are as much as 400 ft 

thick. The basalt is thickest toward probable volcano sources, 

such as Owyhee Butte, Deer Butte, Wrangle Butte, Sacramento Butte, and Iron Mountain that are outside the study 

area (figs. 1, 2). Cedar Mountain, which is a few miles 

north of the study area, also contributed some thin flows. 

The basalts that interfinger with the upper Miocene sedimentary and pyroclastic rocks in and south of Chalk Basin 

are also presumably of late Miocene age. Other basalts at 

The Hole in the Ground yielded early Pliocene ages of 

4.06±0.41 Ma, 4.0910.34 Ma, and 4.4910.38 Ma (Hart, 

1982; Hart and Mertzman, 1983).

Mineral Resources of the Lower Owyhee Canyon Wilderness Study Area, Malheur County, Oregon F7
Basalt and gabbro sills and dikes occur in and near 

Chalk Basin and at The Hole in the Ground. These intrusions may have also fed minor basalt flows. Hydrothermal 

systems associated with the sills and dikes resulted in oxidation of basalt, deposition of hematite in porous sedimentary 

and pyroclastic rocks, deposition of fluorite veins, and 

widespread recrystallization and silicification of limestone. 

The silicification may have involved redistribution of available silica from abundant chert that was already present. 

The chert may have formed when silica was introduced into 

the lacustrine environment during basaltic or rhyolitic volcanism. Studies by the U.S. Bureau of Mines in the vicinity 

of the sills and dikes of the Chalk Basin area indicate widespread alteration of volcanic glass to clinoptilolite and to a 

clay that has commercial properties; the rock samples contain 

elevated concentrations of arsenic (107-178 parts per million, ppm), fluorine (130-1,600 ppm), and molybdenum (18- 

231 ppm). These findings might also be the result of 

hydrothermal systems associated with the sills and dikes.

Pliocene and Quaternary conglomerate as thick as 100 

ft is most abundant on the plateau rims on both sides of the 

Owyhee River in the southern half of the study area. Distribution of the conglomerate reflects the pre-Owyhee canyon 

paleovalley, which the present drainage closely follows. The 

clasts are mostly of basalt and welded tuff but also minor 

chert and quartzite. Chert and quartzite clasts most likely 

came from outside the Oregon segment of the Owyhee 

drainage because chert in upper Miocene sedimentary rocks 

in the study area was not exposed to erosion at the time the 

conglomerate was deposited. Conglomerate that covers 

benches 100 to 200 ft above the present canyon bottom 

were laid down during excavation of the canyon and must 

be younger than the conglomerate on the rims.

Pliocene and Quaternary basalt flows as thick as 300 

ft filled parts of the Owyhee paleocanyon in the north part 

of the study area. A possible source of the basalt is an 

unnamed butte that rises on the north side of Bogus Bench, 

6 mi east of the study area (fig. 1). The flows must have 

dammed the Owyhee paleocanyon as they crossed it, and 

flow remnants indicate the basalt reached at least 6 mi south 

of Lambert Rocks and into The Hole in the Ground area.

Large Quaternary basalt flows cover much of the region of the study area. Within the study area they occur in 

the Saddle Butte lava field and at Lambert Rocks; three 

areas of flow remnants, too small to map on fig. 2, occur 

just above the low-water level of the Owyhee River north 

of Lambert Rocks. Basalt tongues that descend existing 

drainages show that these basalt flows are very young. The 

three minor flow remnants north of Lambert Rocks may be 

part of one flow, possibly the youngest in the study area, 

that may have dammed the river briefly. The large lava 

flows at Lambert Rocks flowed northwestward down the 

Bogus Creek drainage from a butte north of Arock and 6 mi 

southeast of the study area (fig. 1). No clearly defined vent 

was found for the Saddle Butte lava field. This basalt may

have extruded from one or more fissures that are now buried 

beneath the flows. The minor flow along the Owyhee River 

must have had one or more local dike sources, but none 

were found. Both the Lambert Rocks and Saddle Butte flows 

reached the Owyhee River canyon, but it is not clear if the 

basalt was voluminous enough to dam the river. Three warm 

springs along the canyon at river level in the Lambert Rocks 

area suggest a Quaternary age for this basalt.

Holocene deposits include landslide deposits mostly 

along the Owyhee River canyon below the basalt cliffs and 

alluvium mostly along the Owyhee River.

The few faults in the study area are vertical, strike 

predominantly north and west, and have vertical displacements as much as 300 ft. If all the conglomerate on the 

plateau rims had been deposited at approximately the same 

time, the elevation changes of the rim from about 3,700 ft 

to 4,800 ft suggest a relative uplift of at least 1,000 ft of the 

northern part of the study area since Pliocene or early Quaternary time.

Geochemical Studies

A reconnaissance geochemical survey was conducted 

in the Lower Owyhee Canyon Wilderness Study Area in 

the summer of 1985 and the fall of 1988. Reconnaissance 

surveys allow the scientist to evaluate large areas for indications of mineralization but are not designed to find individual deposits. The spacing of samples, however, allows 

large areas to be subdivided rapidly at low cost into zones 

of favorable geochemical provinces and mineralized districts. 

Minus-80-mesh stream sediments, heavy-mineral concentrates derived from stream sediments and rocks were selected as the sample media in this study. Stream sediments 

were sampled at 58 sites, and heavy-mineral concentrates 

were prepared from them; 68 rocks were sampled at 61 sites.

Stream-sediment samples were collected from the active alluvium in the stream channel. Each sample was 

composited from several localities along a channel length 

of approximately 50 ft. The stream sediments were sieved 

through an 80-mesh screen and pulverized to a fine powder 

before analysis. The heavy-mineral concentrates were sieved 

through a 10-mesh screen and then panned until most of the 

quartz, feldspar, clay-sized material, and organic matter were 

removed. The remaining light minerals were separated from 

the heavy minerals by using a heavy liquid (bromoform, 

specific gravity 2.8). The magnetite and ilmenite were then 

removed by an electro-magnet at a setting of 0.2 amperes, 

and the remainder was separated into nonmagnetic and 

slightly magnetic fractions using an amperage setting that 

approximates a setting of 0.6 amperes at a side tilt of 10 

degrees and a forward slope of 15 degrees. The nonmagnetic 

fractions of the concentrates were ground to a fine powder 

before analysis for this study. Stream sediments represent a 

composite of the rock and soil exposed upstream from the

F8 Mineral Resources of Wilderness Study Areas: East-Central Oregon
sample site. The heavy-mineral concentrate represents the 

heavy-mineral components of the rocks exposed in the 

drainage basin and permits determination of some elements 

that are not easily detected in bulk stream sediments. Minerals in the nonmagnetic fraction of the heavy-mineral concentrates could include ore-forming and ore-related minerals 

if ore-mineralization has occurred in the drainage basin. 

Rocks were taken from mineralized and unmineralized outcrops and from stream float Samples that appeared fresh 

and unaltered were collected to provide information on geochemical background values. Altered or mineralized samples 

were collected to determine the suite of elements associated 

with the observed alteration or mineralization. The rocks 

were crushed and pulverized to a fine powder before analysis.

The heavy-mineral concentrates, stream sediments, 

and rocks were analyzed for 31 elements by direct-current 

arc semiquantitative emission spectrographic analysis 

(Grimes and Marranzino, 1968; Crock and others, 1983). 

The rocks and the minus-80-mesh stream sediments were 

also analyzed for certain elements by more sensitive methods: for antimony, arsenic, bismuth, cadmium, and zinc by 

the method described by O'Leary and Viets (1986), for 

gold by the method described by Thompson and others 

(1986), and for mercury by the method described by 

Koirtyohann and Khalil (1976). Analytical data on which 

the following account is based is available in Adrian and 

others (1990).

Stream-sediment samples from several drainages in 

the study area have anomalous concentrations of one or 

more of the following elements: arsenic, barium, bismuth, 

lead, mercury, silver, and tin. Panned concentrates from the 

northern part of the study area and west of Lambert Rocks 

(fig. 2) have high concentrations of barium (more than 10,000 

ppm). The barium probably comes from the mineral barite, 

although barite was not identified in outcrops. Some of the 

barium sources may be outside the north boundary of the 

study area.

Some panned concentrates also contain high concentrations of bismuth (200 ppm, one sample), lead (2,000 ppm, 

one sample), and tin (1,000-2,000 ppm, three samples). Most 

of these samples are from small drainages (less than 2 mi2). 

However, one sample containing 1,500 ppm tin was from a 

large drainage (about 18 mi2) on the flank of Iron Mountain 

(fig. 1); most of this drainage is outside the study area. The 

presence of large concentrations of bismuth, lead, and tin in 

panned concentrates could be due to local mineralization 

related to volcanic processes. In addition, some of the tin in 

two samples from north of Chalk Basin may have been 

reconcentrated from altered tuffaceous sedimentary rock.

A stream-sediment sample from a small drainage west 

of Lambert Rocks (fig. 2) has an anomalous concentration 

of silver (0.5 ppm).

Anomalous concentrations of arsenic (9-24 ppm) in 

stream sediments from drainages north of Lambert Rocks 

are especially widespread in the study area near Wrangle

Butte and in the area containing high values of barium near 

The Hole in the Ground. In the Wrangle Butte area and 

near Lambert Rocks, the arsenic is associated with 5 to 50 

ppm molybdenum in some stream sediments.

Anomalous concentrations of mercury (0.04-0.14 

ppm) were found in 12 stream sediment samples scattered 

the length of the study area, mostly in the southern half. 

Mercury occurs with molydenum in one sample from the 

southern half and with arsenic in two samples from near 

The Hole in the Ground.

About one-third of the rock samples contain anomalous concentrations of one or more of the following elements: antimony (3-6 ppm), arsenic (10-700 ppm), mercury 

(0.26-0.36 ppm), molybdenum (5-200 ppm), silver (0.5 

ppm), tin (10 ppm), and zinc (200-500 ppm). The silver is 

in two samples (silicified sedimentary rock and amygdular 

quartz) from southern Chalk Basin near the drainage that 

yielded a stream-sediment sample having 0.5 ppm silver. 

Arsenic, molybdenum, and zinc occur in rocks near the 

basalt sill in Chalk Basin and at Lambert Rocks. Tin is in 

samples of altered conglomerate and welded tuff from west 

of Iron Point. Mercury is in a sample from south of Lambert Rocks and in one from near The Hole in the Ground.

The high concentrations of barium, bismuth, lead, and 

tin in some panned concentrates, the anomalous concentrations of arsenic, mercury, molybdenum, and silver in some 

stream sediments, and the anomalous concentrations of antimony, arsenic, mercury, molybdenum, silver, tin, and zinc 

in some rocks indicate widespread epithermal mineralization in the study area and are consistent with the Miocene 

to Holocene basaltic and rhyolitic volcanism and the hot 

springs in the study area. The Hole in the Ground, Chalk 

Basin, and Lambert Rocks areas, where argillic alteration 

and moderate silicification are seen, appear to have been 

more affected by hydrothermal processes than other parts 

of the study area.

Bukofski and others (1984) found gold (5-135 parts 

per billion, ppb) in 13 of 120 stream-sediment samples collected from a region that includes the Lower Owyhee Canyon Wilderness Study Area. The gold-bearing samples from 

tributaries to the Owyhee River are scattered throughout the 

region and do not show a clear geographic concentration. 

Gold-bearing samples come from drainages from Owyhee 

Butte, the Saddle Butte lava field, Wrangle Butte through 

Chalk Basin, Cedar Mountain, and Deer Butte (fig. 2). These 

data, in addition to the widespread minor-element anomalies mentioned above and the volcanism, hot springs, argillic 

alteration, and silicification, suggest widespread gold mineralization in the study area.

Geophysical Studies

A regional aeromagnetic survey was flown over the 

study area in 1972 (U.S. Geological Survey, 1972). Data

Mineral Resources of the Lower Owyhee Canyon Wilderness Study Area, Malheur County, Oregon F9
were collected along parallel east-west flightlines spaced at 

an interval of 2 mi and flown at a constant barometric elevation of 9,000 ft above sea level. The Earth's main field 

was subtracted from the data, which were then plotted and 

hand contoured at a scale of 1:250,000. Additional aeromagnetic data for the Boise quadrangle (geoMetrics Inc., 

1979) and the Jordan Valley quadrangle (Geodata International, Inc., 1980) were published for the Department of 

Energy, both at a scale of 1:500,000. These data consist of 

east-west profiles spaced at intervals of 3 mi and flown by 

helicopter at an average height of 400 ft above the ground 

surface.

Magnetic minerals, where locally concentrated or depleted, 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. The majority of the anomalies in the study area are probably caused by the preponderance of lava flows and other volcanic rocks. Survey aircraft 

maintained an altitude of 4,000 to 6,000 ft above the ground 

surface, a distance sufficient to suppress most of the shortwavelength anomalies generated by the smaller rock units 

at or near the surface. These short-wavelength anomalies 

may be seen on the low-level profiles across the study area 

(geoMetrics Inc., 1979; Geodata International, Inc., 1980). 

The aeromagnetic map (U.S. Geological Survey, 1972) 

shows that the study area lies in an area of linear, north- to 

northeast-trending regional magnetic lows (contour values 

of 2,400-2,600 gammas) bordered by highs that have similar 

trends but lie a few miles outside the study area. The highs 

are associated with structurally uplifted areas that expose 

thick sequences of Tertiary volcanic rocks near the center 

parts, and these rocks may be the source of the regional 

magnetic highs. A north-trending boundary that approximately follows long 117°30' W. near the east border of the 

study area appears to separate two areas of differing magnetic patterns. This boundary appears to be caused by a 

major fault that is not well expressed in the exposed geology and is discussed in the paragraph on gravity interpretation. The weak magnetic anomalies within the study area 

may be due in part to the edges of magnetic volcanic rock 

units that are exposed along the Owyhee River canyon. In 

summary, the magnetic data appear to reflect outcrops of 

magnetic volcanic rocks and provide no evidence indicating 

the presence of any mineral resources in the study area.

A gravity survey of this area was conducted by the 

U.S. Geological Survey in 1986 and 1987 to supplement 

data already available from the National Geophysical Data 

Center, Boulder, CO 80303. Station spacing ranges from 

about 3 to 5 mi, and about 80 stations are situated within or 

near the border of the study area. The gravity field of the 

study area south of lat 43°05' N. is relatively featureless 

(fig. 3). The study area north of this latitude lies within a 

subcircular gravity low having a maximum amplitude of 17

milligals and a width of about 15 mi. The east side of this 

low is marked by a steep gravity gradient sloping down to 

the west toward the study area. The gradient is interpreted 

as caused by a fault (fig. 3), probably concealed, striking 

north at about long 117°30' W., nearly coincident to the 

magnetic boundary previously mentioned. On the basis of 

the gravity interpretation, this fault appears to be the southernmost end of a major fault extending at least 70 mi north 

of the study area (Lillie, 1977). The subcircular gravity low 

west of this fault does not have an easily identified source. 

The low extends 15 mi northwest across the Owyhee River 

canyon. The nadir of the low is about 2 mi northwest of the 

Iron Point area, where the exposed section of silicic welded 

tuff is thickest. Explanations for a gravity low of this kind 

include (1) a small concealed granitic batholith, (2) a concealed sedimentary basin filled with low-density sediments,

Figure 3. Complete Bouguer gravity anomaly map of Lower 

Owyhee Canyon Wilderness Study Area (shaded area) and 

vicinity, Malheur County, Oregon. Contour interval 2 milligals; hachures indicate direction of lower gravity value; dots 

represent gravity stations. Bold solid line, fault probably concealed. Bold dashed outline, possible caldera discussed in text.

F10 Mineral Resources of Wilderness Study Areas: East-Central Oregon
or (3) a concealed older caldera complex containing lowdensity fill. The third explanation appears to be the most 

likely on the basis of geologic mapping and thickness of the 

volcanic and sedimentary units. It also offers a possible 

source for some of the nearby Tertiary rhyolites and welded 

tuffs that are exposed to the south as well as in the canyon 

floor within the gravity low. Mineralization might be associated with such a caldera.

Aerial gamma-ray spectrometer measurements are 

available along the 3-mi-spaced east-west profiles illustrated 

by geoMetrics Inc. (1979), and by Geodata International, 

Inc. (1980). Statistically significant anomalies for uranium 

(designated as anomalies 106 and 118 by geoMetrics Inc., 

1979) were found within the boundaries of the study area in 

the Boise quadrangle (north of lat 43° N.). The anomalies 

are not large in amplitude, are associated with moderate 

potassium anomalies, and are located over broad areas of 

Tertiary sedimentary rocks (mostly lake beds) in the lower 

parts of Owyhee River canyon. These associations suggest 

that the anomalies are caused by the relatively normal 

amounts of uranium and potassium to be expected in many 

sedimentary rocks of this sort and that the anomalies probably have no economic significance.

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. 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 conjuction with geologic 

and geophysical maps may reveal new relations 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. This study area is underlain 

mostly 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 indicate that the entire Lower Owyhee Canyon Wilderness Study Area has low 

mineral resource potential for gold, silver, lead, zinc, antimony, and mercury with a certainty level B. The potential 

is indicated by widespread samples showing anomalous 

amounts of gold, and silver; anomalous amounts of arsenic, 

barium, bismuth, lead, and tin commonly occur with gold 

and silver mineralization in the region, and anomalous lead, 

zinc, tin, molybdenum, antimony, mercury, and molybdenum are found in scattered locations in the study area. The 

geology of the study area is a result of abundant silicic and 

basaltic volcanism as recently as Holocene; several hot

springs occur in the study area, and broad areas of argillic 

alteration and silicification occur in The Hole in the Ground, 

Chalk Basin, and Lambert Rocks areas. These data only 

suggest that the study area exposes the outer parts of a 

complex zone of hydrothermal alteration that involved precious- and base-metals mineralization.

The mineral resource potential for barite is low in 

two areas in the northern and west-central parts of the study 

area (fig. 2). This potential is indicated by high 

concentrations of barium in panned-concentrate samples. 

The high concentrations of barium, probably in the mineral 

barite, may be a result of stream transport dynamics rather 

than a definitive criterion of significant barite deposits 

upstream from the sample sites. Some of the barite sources 

may be outside the boundary of the wilderness study area. 

A certainty level B is assigned because no veins or bedded 

deposits of barite were found and because the geologic 

setting is not clearly indicative of barite deposits.

Wells were drilled for oil and gas 95 mi northeast of 

the study area in the western Snake River basin of Oregon 

and Idaho. Study of these wells and the regional geology 

led Newton and Corcoran (1963) to conclude that the depositional environments of the Snake River basin resemble 

other nonmarine basins that produce oil and gas and that 

hydrocarbons formed there during the late Miocene and 

early Pliocene. The Late Miocene and early Pliocene, however, was a time period characterized by volcanism in the 

study area. Warner (1980) suggested that southeastern Oregon is underlain by Mesozoic and Tertiary rocks that contain potential source material for petroleum. However, 

pre-Tertiary rocks exposed about 40 mi southeast of the 

study area at South Mountain in Idaho and about 80 mi to 

the southwest in the the Pueblo Mountains in Nevada and 

Oregon are metasedimentary and metavolcanic rocks that 

would not be good potential petroleum sources. During this 

study no surficial evidence was found that indicates the 

presence of hydrocarbons at depth. Any potential hydrocarbon reservoirs that might be present beneath the rocks exposed in the study area probably would have to be located 

by seismic surveys. Although it is likely that heat from 

volcanism in the area would have driven off any hydrocarbons, hydrocarbon concentrations below the rocks exposed 

in the southern part of the study area cannot be ruled out. 

The possibility that a caldera underlies the northern part of 

the study area suggests that the resource potential for oil 

and gas is remote for that part of the study area because 

hydrocarbon reservoirs would be unlikely to survive at the 

site of a caldera. Fouch (1983) estimated the oil and gas 

potential of the study area to be low. However, available 

geological and geophysical information indicates that the 

likelihood for occurrence of oil and gas within the study 

area is very low to remote; for the purpose of this study the 

energy resource potential for oil and gas is considered low, 

certainty level B, for the southern two-thirds of the study 

area (fig. 2).

Mineral Resources of the Lower Owyhee Canyon Wilderness Study Area, Malheur County, Oregon F11
Four hot springs were found along the Owyhee River 

in the study area. Three of them are between the Quaternary basalt of the Saddle Butte lava field on the west and 

the Lambert Rocks basalt flows on the east. One hot spring 

is near the south end of the study area, about 2 mi southwest of a small basalt vent on the south flank of Owyhee 

Butte. The study area is on the west flank of a broad zone 

of high heat flow defined by Muffler (1979) and is near the 

100-milliwatts-per-square-meter contour of regional heat 

flow. The warm springs in the study area may be a result of 

young basaltic volcanism or of deep circulation in a region 

of slightly elevated heat flow. The relatively small basalt 

vents, most likely extending from great depth, are poor targets for geothermal heat production. For these reasons the 

two small areas containing hot springs in the study area 

have a low potential for geothermal energy resource with a 

certainty level C (fig. 2).

REFERENCES CITED

Adrian, B. M., Turner, R.L., Fey, D.L., Hageman, P.L., and 

Roushey, B.H., 1990, Analytical results and sample locality 

map of stream-sediment, heavy-mineral-concentrate, and rock 

samples from the Lower Owyhee Canyon Wilderness Study 

Area, Malheur County, Oregon: U.S. Geological Survey OpenFile Report 90-471, 23 p.

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.

Berry, M.R., Castor, S.B., and Robins, J.W., 1982, National uranium resource evaluation, Jordan Valley quadrangle, Oregon 

and Idaho: Grand Junction, Colo., Bendix Field Engineering 

Corp., prepared for U.S. Department of Energy, Open-File 

Report PGJ/F-132(82), 33 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.

Campion, K.M., 1979, Diagenetic alteration and formation of 

authigenic minerals in the Miocene "Rome beds," southeastem Oregon: Columbus, Ohio State University Ph.D. dissertation, 185 p.

Causey, J.D., 1989a, Mineral resources of the Lower Owyhee 

Canyon study area, Malheur County, Oregon: U.S. Bureau of 

Mines Open-File Report MLA-6-89, 37 p.

Causey, J.D., 1989b, Mineral resources of the Owyhee Breaks 

study area, Malheur County, Oregon: U.S. Bureau of Mines 

Open-File Report MLA-15-89, 21 p.

Clifton, R.A., 1987, Natural and synthetic zeolites: U.S. Bureau of 

Mines Information Circular IC-9140,21 p.

Crock, J.G., Lichte, F.E., and Briggs, P.H., 1983, Determination 

of elements in National Bureau of Standards' Geological 

Reference Materials SRM 278 obsidian and SRM 668 basalt 

by inductively coupled argon plasma atomic emission spectrometry: Geostandards Newsletter, no. 7 p. 335-340.

Deer, W.A., Howie, R.A., and Zussman, J., 1963, Rock-forming 

minerals; v. 4, Framework silicates: New York, John Wiley, 

435 p.

Ellison, B.E., 1968, Stratigraphy of the Burns Junction-Rome area, 

Malheur County, Oregon: Corvallis, Oregon State University 

M.S. thesis, 89 p.

Evans, J.G., 1987, Geologic map of the Owyhee Canyon Wilderness Study Area, Malheur County, Oregon: U.S. Geological 

Survey Miscellaneous field Studies Map MF-1926, scale 

1:62,500.

Eyde, T.H., 1981, Chemical and physical properties of natural 

zeolites and their potential industrial applications, in Hausen, 

D.M., and Park, W.C., eds., Process mineralogy; extractive 

metallurgy, mineral exploration, energy resources: American 

Institute of Mining, Metallurgical, and Petroleum Engineers, 

Metallurgical Society Symposium, 110th Annual Meeting, 

Chicago, Illinois, p. 645-656.

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

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

Geodata International, Inc., 1980, Aerial radiometric and magnetic survey, Jordan Valley [1° by 2°] National Topographic 

Map, Idaho and Oregon: Grand Junction, Colo., U.S. Department of Energy, National Uranium Resource Evaluation Program Report GJBX-095(80), variously paginated.

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

Boise [1° by 2°] quadrangle, Oregon/Idaho: Grand Junction, 

Colo., U.S. Department of Energy, National Uranium Resource Evaluation Program Report 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, and Baxter, Gary, 1983, 

Geology and mineral resources of 18 BLM 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-CT1-1086,108 p.

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

alternating-current spark emission spectrographic field methods for the semiquantitative analysis of geologic materials: 

U.S. Geological Survey Circular 591,6 p.

Harre, E.A., and Young, R. D., 1983, Nitrogen compounds, in 

Lefond, S.J., editor-in-chief, Industrial minerals and rocks, 

vol. 2: New York, American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc., p. 961-988.

Hart, W.K., 1982, Chemical, geochronologic and isotopic significance of low-K, high-alumina olivine tholeiite in the northwestern Great Basin, U.S.A.: Cleveland, Ohio, Case Western 

Reserve University Ph.D. dissertation, 410 p.

Hart, W.K., Aronson, J.L., and Mertzman, S.A., 1983, Areal distribution and age of low-K, high-alumina olivine tholeiite 

magmatism in the northwestern Great Basin: Geological Society of America Bulletin, v. 95, no. 2, p. 186-195.

Hart, W.K., and Mertzman, S.A., 1983, Late Cenozoic volcanic 

stratigraphy of the Jordan Valley area, southeastern Oregon: 

Oregon Geology, v. 45, no. 2, p. 12-19.

Helfferich, F., 1964, A simple identification reaction for zeolites 

(molecular sieves): The American Mineralogist, v. 49, no. 

11-12, p. 1752-1754.

F12 Mineral Resources of Wilderness Study Areas: East-Central Oregon
Koirtyohann, S.R., and Khalil, Moheb, 1976, Variables in the determination of mercury by cold vapor atomic absorption: 

Analytical Chemistry, v. 48, no. 1, p. 136-139.

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

Mansfield, G.R., and Boardman, Leona, 1932, Nitrate deposits of 

the United States: U.S. Geological Survey Bulletin 838,107 p.

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

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

Muffler, L.J.P., 1979, Assessment of geothermal resources of the 

United States, 1978: U.S. Geological Survey Circular 

790,163 p.

Mumpton, F.A., ed., 1983, Zeo-trip 183, an excursion to selected 

zeolite deposits in eastern Oregon, southwestern Idaho, and 

northwestern Nevada, and to the Tahoe-Truckee water reclamation plant, Truckee, California: Brockport, N.Y., State 

University College, Department of Earth Sciences, International Committee on Natural Zeolites, 72 p.

Munson, R.A., and Sheppard, R.A., 1974, Natural zeolites: their 

properties, occurrences, and uses: Minerals Science and Engineering, v. 6, no. 1, p. 19-34.

New comb, R.C., 1961, Ground water in the western part of the 

Cow Creek and Soldier Creek grazing units, Malheur County, 

Oregon: U.S. Geological Survey Water-Supply Paper 1475- 

E, p. 159-172.

Newton, V.C., and Corcoran, R.E., 1963, Petroleum geology of 

the western Snake River Basin, Oregon-Idaho: Oregon Department of Geology and Mineral Industries, Oil and Gas 

Investigations, No. 1, 67 p.

O'Leary, R.M., and Viets, J.G., 1986, Determination of antimony, 

arsenic, bismuth, cadmium, copper, lead, molybdenum, silver, 

and zinc in geologic materials by atomic absorption spectrometry using a hydrochloric acid-hydrogen peroxide digestion: Atomic Spectroscopy, v. 7, no. 1, p. 4-8.

Plumley, P.S., 1986, Volcanic stratigraphy and geochemistry of The 

Hole in the Ground area, Owyhee Plateau, southeastern Oregon: Moscow, Idaho, University of Idaho M.S. thesis, 161 p.

Regis, A.J., 1967, Economic geology and mineralogy of the Norton 

Company pyroclastic zeolite deposit in the western United 

States: Norton Company, Refractories Division Research and 

Development Department, 7 p.

Sand, L.B., and Regis, A.J., 1979, Mineral distribution in size 

fractions of AIME preprint 67-H-317,14 p.

Santini, K.N., and LeBaron, M.R., 1982, Geology of the Rome 

zeolite deposit, Malheur County, Oregon: Society of Metallurgical Engineers American Institute of Mining, Metallurgical, and Petroleum Engineers, First International Fall Meeting, Honolulu, Hawaii, 10 p.

Selby, S.M., 1968, Standard mathematical tables, 16th ed.: Cleveland, Ohio, The Chemical Rubber Company, 692 p.

Sheppard, R.A., 1976, Zeolites in sedimentary deposits of the 

northwestern United States potential industrial minerals, in 

Eleventh Industrial Minerals Forum: Montana Bureau of 

Mines and Geology Special Publication 74, p. 69-84.

Sheppard, R.A., and Gude, A.J., 3d, 1969, Authigenic fluorite in 

Pliocene lacustrine rocks near Rome, Malheur County, Oregon, in Geological Survey research 1969: U.S. Geological 

Survey Professional Paper 650-D, p. D69-D74.

 1973, Zeolites and associated authigenic silicate minerals 

in tuffaceous rocks of the Big Sandy Formation, Mohave 

County, Arizona: U.S. Geological Survey Professional Paper 

830, 36 p. 

-1974, Chert derived from magadiite in a lacustrine deposit

near Rome, Malheur County, Oregon: U.S. Geological Survey 

Journal of Research, v. 2, no. 5, p. 625-630.

Thompson, C.E., Nakagawa, H.M., and Van Sickle, G.H., 1968, 

Rapid analysis for gold in geologic materials, in Geological 

Survey research 1968: U.S. Geological Survey Professional 

Paper 600-B, p. B130-B132.

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.

U.S. Geological Survey, 1972, Aeromagnetic map of the Adel and 

parts of the Burns, Boise, and Jordan Valley 1° by 2° quadrangles, Oregon: U.S. Geological Survey open-file report, scale 

1:250,000.

Vander Meulen, D.B., Barlock, V.E., Plumley, P.S., Frisken, J.G., 

Griscom, Andrew, and Causey, J.D., 1990, Mineral resources 

of the Blue Canyon and Owyhee Breaks Wilderness Study 

Areas, Malheur County, Oregon: U.S. Geological Survey 

Bulletin 1741-G, 28 p.

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

meridian: U.S. Geological Survey Miscellaneous Geologic 

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

Walker, G.W., and Repenning, C.A., 1966, Reconnaissance geologic map of the west half of the Jordan Valley quadrangle, 

Malheur County, Oregon: U.S. Geological Survey Miscellaneous Geologic Investigations Map 1-457, scale 1:250,000.

Warner, M.M., 1980, Southern Idaho, northern Nevada, southeastern Oregon a prime regional target for petroleum exploration: 

Wyoming Geological Association, Earth Science Bulletin, v. 

13, no. 1, p. 19-40.

Williams, I.A., 1918, Nitrate deposits of southeastern Oregon: 

Mining and Scientific Press, v. 117, p. 285-289.

Mineral Resources of the Lower Owyhee Canyon Wilderness Study Area, Malheur County, Oregon F13

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 resource 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 resource potential.

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

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

o

Q_

D

o

CO

LLJ

C£

LL.

O

A

U/A

UNKNOWN POTENTIAL

B

H/B

HIGH POTENTIAL

M/B

MODERATE POTENTIAL

L/B

LOW POTENTIAL

C

H/C

HIGH POTENTIAL

M/C

MODERATE POTENTIAL

L/C

LOW POTENTIAL

D

H/D

HIGH POTENTIAL

M/D

MODERATE POTENTIAL

L/D

LOW POTENTIAL

N/D

NO POTENTIAL

LEVEL OF CERTAINTY

Abstracted with minor modifications from:

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 1638, 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.

F16 Mineral Resources of Wilderness Study Areas: East-Central Oregon
RESOURCE/RESERVE CLASSIFICATION

ECONOMIC

MARGINALLY 

ECONOMIC

SUBECONOMIC

IDENTIFIED RESOURCES

Demonstrated

Measured

Rest

Indicated

;rves

I 

Marginal 

Reserves

Demonstrated 

Subeconomic 

Resources

Inferred

Inferred 

Reserves

Inferred 

Marginal 

Reserves

Inferred 

Subeconomic 

Resources

UNDISCOVERED RESOURCES

Probability Range

Hypothetical Speculative

I 

l

l 

1

I 

l

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 Lower Owyhee Canyon Wilderness Study Area, Malheur County, Oregon F17
GEOLOGIC TIME CHART

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

EON

Phanerozoic

Proterozoic

pre-Archean2

ERA

Cenozoic

Mesozoic

Paleozoic

Late Proterozoic

Middle Proterozoic

Early Proterozoic

Late Archean

Middle Archean

Early Archean

PERIOD

Neogene

Subperiod

Tertiary

Jurassic

Triassic

Permian

Pennsylvanian 

Carboniferous

Periods 

Misslssippian

Devonian

Silurian

Ordovician

Cambrian

(lQr\r\j\

EPOCH

Holocene

Pleistocene

Pliocene

Miocene

Oligocene

Eocene

Paleocene

Late

Early

Late 

Middle 

Early

Late 

Middle 

Early

Late 

Early

Late 

Middle 

Early

Late 

Early

Late 

Middle 

Early

Late 

Middle 

Early

Late 

Middle 

Early

Late 

Middle 

Early

AGE ESTIMATES OF 

BOUNDARIES IN 

MILLION YEARS (Ma)

 0.010

 1.7

 5

O A

t Q

 55

 66

96

 205

290 

 -330

 360

 410

 435

j \j\j

 j/ \j

 1600

^j\j\j

j\j\j\j

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

Informal time term without specific rank.

F18 Mineral Resources of Wilderness Study Areas: East-Central Oregon
SELECTED SERIES OF U.S. GEOLOGICAL SURVEY PUBLICATIONS

Periodicals

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topographic, hydrologic, and geologic investigations. They also include 

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Oil and Gas Investigations Charts show stratigraphic information 

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Miscellaneous Field Studies Maps are multicolor or black-andwhite maps on topographic or planimetric bases on quadrangle or irregular areas at various scales. Pre-1971 maps show bedrock geology 

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maps are primarily black-and-white maps on various subjects such as 

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Note. Prices of Government publications listed in older catalogs, 

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prices charged may differ from the prices in catalogs, announcements, 

and publications.
il; : flf'.-;ii.«i ': JM'i'* *-, i.fjrfjfi /'*