Mineral Resources of the Lower John Day 

and Thirtymile Wilderness Study Areas, 

Sherman and Gilliam Counties, Oregon

U.S. GEOLOGICAL SURVEY BULLETIN 1743-A

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Chapter A

Mineral Resources of the Lower John Day 

and Thirtymile Wilderness Study Areas, 

Sherman and Gilliam Counties, Oregon

By JAY A. ACH, SCOTT A. MINOR,

JAMES G. FRISKEN, and RICHARD J. BLAKELY

U.S. Geological Survey

HARRY W. CAMPBELL and EDWARD L. McHUGH 

U.S. Bureau of Mines

U.S. GEOLOGICAL SURVEY BULLETIN 1743

MINERAL RESOURCES OF WILDERNESS STUDY AREAS: 

JOHN DAY REGION, OREGON
DEPARTMENT OF THE INTERIOR 

DONALD PAUL HODEL, Secretary

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director

Any use of trade names and trademarks 

in this publication is for descriptive 

purposes only and does not constitute 

endorsement by the U.S. Geological Survey

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1988

For sale by the

Books and Open-File Reports Section

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Library of Congress Cataloging-in-Publication Data

Mineral resources of the Lower John Day and Thirtymile 

Wilderness Study Areas, Sherman and Gilliam Counties, 

Oregon.

(U.S. Geological Survey bulletin ; 1743-A)

Supt. of Docs, no.: I 19.3:1743-A

Bibliography: p.

1. Mines and mineral resources Oregon Lower John 

Day Wilderness. 2. Mines and mineral resources 

Oregon Thirtymile Wilderness. 3. Lower John Day 

Wilderness (Or.) 4. Thirtymile Wilderness (Or.) I. Ach, 

Jay A. II. Series.

QE75.B9 no. 1743-A 557.3 s 88-600189 

[TN24.07] [553'.09795'64]
STUDIES RELATED TO WILDERNESS

Bureau of Land Management Wilderness Study Areas

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 of 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 parts of the 

Lower John Day (OR-005-006) and Thirty mile (OR-005-001) Wilderness Study Areas, 

Sherman and Gilliam Counties, Oregon.

CONTENTS

Summary Al

Abstract Al

Character and setting Al 

Identified resources Al

Mineral resource potential of the Lower John Day Wilderness Study Area Al 

Mineral resource potential of the Thirtymile Wilderness Study Area A3 

Introduction A3

Area description A3 

Previous and present investigations A3 

Acknowledgments AS 

Appraisal of identified resources AS 

Mining history AS 

Appraisal of mineral resources AS 

Assessment of mineral resource potential A6 

Geology A6 

Geochemical studies A7 

Geophysical studies A8

Magnetic data A8 

Gravity studies A9 

Radiometric data A9 

Conclusions A10

Mineral and energy resource potential of the Lower John Day Wilderness Study 

Area A10

Mineral resource potential A10 

Energy resource potential AlO

Mineral and energy resource potential of the Thirtymile Wilderness Study 

Area All

Mineral resource potential All 

Energy resource potential A12 

References cited A12 

Appendixes

Definition of levels of mineral resource potential and certainty of

assessment A16

Resource/reserve classification A17 

Geologic time chart A18

FIGURES

1 Index map showing location of the Lower John Day and Thirtymile Wilderness Study 

Areas, Sherman and Gilliam Counties, Oregon A2

2 Map showing mineral resource potential and geology of the Lower John Day and 

Thirtymile Wilderness Study Areas, Sherman and Gilliam Counties, Oregon A4

Contents

Mineral Resources of the Lower John Day 

and Thirtymile Wilderness Study Areas, 

Sherman and Gilliam Counties, Oregon

By Jay A. Ach, Scott A. Minor, James G. Frisken, and Richard J. Blakely 

U.S. Geological Survey

Harry W. Campbell and Edward L. McHugh 

U.S. Bureau of Mines

SUMMARY 

Abstract

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

approximately 25,163 acres of the Lower John Day 

(OR-005-006) and Thirtymile (OR-005-001) Wilderness 

Study Areas (17,831 and 7,332 acres, respectively) in northcentral Oregon were evaluated for identified mineral resources (known) and mineral resource potential (undiscovered). In this report, "wilderness study areas" and "study 

areas" refer to the 25,163 acres for which mineral surveys 

were requested. Fieldwork for this report was carried out in 

1985 and 1986. No mines or mining districts are located 

inside the study areas; however, both areas are under lease 

for oil and gas. The Thirtymile Wilderness Study Area has 

790,000 cubic yards of subeconomic gold resources averaging 0.003 troy ounces per cubic yard in two river bars along 

the John Day River. The Lower John Day Wilderness Study 

Area has five river bars that have gold occurrences. The 

Lower John Day and the Thirtymile Wilderness Study Areas 

both have a low mineral resource potential for placer gold in 

the canyon of the John Day River. In addition, part of the 

Thirtymile Wilderness Study Area has a low mineral resource 

potential for gold and (or) mercury in hydrothermal deposits. 

Both study areas have a low resource potential for oil and gas 

and no potential for geothermal energy resources.

Character and Setting

The Lower John Day and Thirtymile Wildcrnesss 

Study Areas are located in north-central Oregon about 40 

mi southeast of The Dalles and about 15 mi west of Condon (fig. 1). Within the study areas, the gently rolling hills

Manuscript approved for publication June 22, 1988.

of the region are deeply incised by the steep, 1,800-ft-deep 

canyon of the John Day River.

Basalt flows of the Columbia River Basalt Group 

cover the entire area studied. A drill hole to the east indicates that the basalt is at least 2,000 ft thick and that it 

overlies rocks of the John Day Formation. Entrenched 

meanders and perched alluvium were left along canyon 

walls by the John Day River as it cut into the surrounding 

terrain.

Identified Resources

Deposits of alluvium along the John Day River in the 

study areas contain placer gold. The Thirtymile Wilderness 

Study Area has 790,000 yd3 of inferred subeconomic gold 

resources averaging 0.003 troy ounces per cubic yard (oz/ 

yd3) in two river bar deposits. No mineral resources were 

identified in the Lower John Day Wilderness Study Area; 

however, five river bars in the study area have gold occurrences totaling 1.0 million yd3 averaging 0.0004 troy oz/yd3 

gold.

Stone, sand, and gravel from the study areas could be 

quarried and used for construction purposes; however, 

suitable material is common elsewhere in the region and 

more accessible to possible markets.

Mineral Resource Potential of the 

Lower John Day Wilderness Study Area

The Lower John Day Wilderness Study Area has low 

mineral resource potential for placer gold in alluvium 

occurring in scattered small river bars in the canyon of the 

John Day River. This potential is indicated by anomalously 

high gold concentrations in stream-sediment samples.

Mineral Resources of the Lower John Day and Thirtymite Wilderness Study Areas, Oregon A1
120°45' 120°30' 120° 15'

APPROXIMATE BOUNDARY

OF

LOWER JOHN DAY

WILDERNESS STUDY AREA

(OR-005-006)

Standard 

Kirkpatrick 

No. 1 well

APPROXIMATE BOUNDARY

OF

THIRTYMILE 

WILDERNESS STUDY AREA

(OR-005-001)

Creek Micron No. 65 claim 

(abandoned)

APPROXIMATE BOUNDARY

OF

NORTH POLE RID£E 

WILDERNESS STUDY ARE~A

(OR-005-008^ GILLIAM \ CO 

WHEELER / CO

19

AREA OF MAP 

218

Figure 1. Index map showing location of the Lower John Day and Thirtymile Wilderness Study Areas, Sherman and 

Gilliam Counties, Oregon. See Minor and others (1988) for discussion of the mineral resource potential of North Pole 

Ridge Wilderness Study Area.

A2 Mineral Resources of Wilderness Study Areas: John Day Region, Oregon
The study area also has low potential for oil and natural gas. Dry holes are located about 14 mi east and 22 mi 

south of the study area. Well logs and various studies 

indicate that suitable source and reservoir rocks are not 

present at these drill sites. However, the existence of more 

favorable source and reservoir rocks beneath the study area 

cannot be ruled out. No favorable reservoir structures are 

known in the study area.

No potential exists for geothermal energy in the study 

area.

Mineral Resource Potential of the 

Thirtymile Wilderness Study Area

In the Thirtymile Wilderness Study Area, a low mineral resource potential exists for placer gold in scattered, 

small deposits of alluvium in the John Day River canyon. 

This potential is indicated by anomalously high gold concentrations in stream-sediment samples. The southern part 

of the study area also has low potential for gold and (or) 

mercury in epithermal deposits. This potential is based on 

a low-level gold and mercury anomaly in a single rock 

sample.

The study area has low potential for oil and natural 

gas. The dry holes mentioned above are located about 14 

and 18 mi from the study area. Potential source and reservoir rocks are likely to be of poor quality. No favorable 

reservoir structures are known in the study area.

No potential exists for geolhermal energy resources in 

the study area.

INTRODUCTION

This mineral resource study is a joint effort by the U.S. 

Geological Survey and the U.S. Bureau of Mines. Mineral 

assessment methods and terminology are discussed in 

Goudarzi (1984). Identified resources are classified according to the system that is a modification of that described by McKelvey (1972) and U.S. Bureau of Mines and 

U.S. Geological Survey (1980). See the appendixes for the 

definition of levels of mineral resource potential and certainty of assessment and for the resource/reserve classification. Studies by the U.S. Geological Survey are designed 

to provide a reasonable scientific basis for assessing the 

potential for undiscovered mineral resources by determining geological units and structures, possible environments 

of mineral deposition, presence of geophysical and gcochemical anomalies, and applicable ore-deposit models. 

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.

Area Description

The U.S. Bureau of Land Management requested that 

a total of 25,163 acres of the Lower John Day 

(OR-005-006) and Thirtymile (OR-005-001) Wilderness 

Study Areas, 17,831 and 7,332 acres, respectively, be 

evaluated for mineral resources and resource potential. The 

study areas are about 40 mi southeast of The Dalles and 

about 15 mi west of Condon, in north-central Oregon (fig. 

1). The topography of the areas is dominated by the precipitous canyon of the John Day River, which has cut 

approximately 1,800 ft below the surrounding topography. 

Elevations range from approximately 600 ft at the canyon 

bottom in the north end to approximately 2,600 ft at the 

canyon rim in the south end of the study areas. The area 

has a scmiarid climate (Slrahler, 1969) and an average of 

about 12 in. of precipitation a year (Meteorology Committee, Pacific Northwest River Basins Commission, 1969). 

The vegetation in the canyon consists mainly of range 

grasses, sagebrush, and juniper trees.

The best access to the study areas is from the John Day 

River via raft or canoe. In a few places, the canyon rim is 

accessible by graded dirt and gravel roads and jeep trails 

leading from Oregon Highways 97 and 206.

Previous and Present Investigations

Swanson and others (1979, 1981) included the study 

areas in regional geologic mapping of the Columbia River 

Basalt Group. The areas are also included in regional 

mapping by Bcla (1982).

Previous reconnaissance studies of the geology and 

mineral resources of wilderness study areas in the region 

were carried out by Davis (1983) and Fouch (1983). The 

uranium resource potential for the region was evaluated as 

part of the U.S. Department of Energy National Uranium 

Resource Evaluation (NURE) program (High Life Helicopters, Inc./ QEB, Inc., 1981).

The U.S. Geological Survey carried out field investigations in the study areas during the summers of 1985 and 

1986. This work included geologic mapping and geochcmical sampling. An analysis was made of available 

geophysical data.

The U.S. Bureau of Mines conducted a library search 

for information on mines and prospects within the study 

areas. Additional data were obtained from U.S. Bureau of 

Land Management mining claim records, from Sherman 

and Gilliam Counties mining claim records, and from the 

U.S. Bureau of Mines Mineral Industry Location System. 

Field studies by U.S. Bureau of Mines personnel were 

carried out in 1986 (Campbell and McHugh, 1987). Rock 

samples were checked for radioactivity and fluorescence. 

The rock samples were also analyzed for gold by combined

Mineral Resources of the Lower John Day and Thirtymile Wilderness Study Areas, Oregon A3
120° 35'

APPROXIMATE BOUNDARY,

OF

LOWER JOHN DAY

WILDERNESS STUDY AREA

(OR-005-006)

EXPLANATION 

Area having low mineral resource potential (L)

X 12 Sample location within area of identified subeconomic

placer gold resources-Numbers refer to Table 2 in 

Campbell and McHugh (1987)

Levels of certainty of assessment 

B Data suggest level of potential 

C Data give good indication of level 

of potential

Au 

Hg 

O,G

Commodities 

Gold 

Mercury 

Oil and gas

[ ] Deposit types

1 Placer deposits in alluvium

2 Epithermal deposits in volcanic and volcaniclastic rocks

Geologic map units

Quaternary alluvium along John Day River too 

small to be shown at scale of this map

Tcr Columbia River Basalt Group (Tertiary)

Normal fault-Dashed where approximate; bar and ball 

on downthrown side; double-headed arrows indicate 

strike-slip component of uncertain direction

'APPROXIMATE BOUNDARY

OF

, /r I THIRTYMILE 

^ f 111 II WILDERNESS STUDY AREA 

1 J ^ (OR-005-001)

L/C Au. Hg|2|

L/B O,G

(entire study area)

2 MILES

Figure 2. Mineral resource polenlial and geology of ihe Lower John Day and Thirlymile Wilderness Sludy Areas, Sherman 

and Gilliam Counlies, Oregon.

A4 Mineral Resources of Wilderness Study Areas: John Day Region, Oregon
fire assay and atomic-absorption analysis and for a variety 

of elements by inductively coupled plasma methods. Alluvial samples were concentrated and inspected for gold and 

other valuable minerals. Complete analytical data are on 

file at the U.S. Bureau of Mines, Western Field Operations 

Center, E. 360 Third Ave., Spokane, WA 99202.

Acknowledgments

The authors gratefully acknowledge the cooperation of 

the U.S. Bureau of Land Management personnel of the 

Prineville District Office, Prineville, Oregon, for providing 

access information and maps of the study areas. Dan E. 

Wermiel, Oregon Department of Geology and Mineral 

Industries, provided much information pertaining to the 

petroleum potential of central Oregon.

APPRAISAL OF IDENTIFIED RESOURCES

By Harry W. Campbell and Edward L. McHugh 

U.S. Bureau of Mines

Mining History

No evidence of mining activity was found in or near 

the Lower John Day or Thirtymile Wilderness Study Areas. 

One abandoned mining claim (Micron No. 65, fig. 1) was 

located in the Thirtymile Wilderness Study Area in 1983; 

11 other claims in the Micron group were located at the 

same time about 5 mi to the south in the North Pole Ridge 

Wilderness Study Area following a report of geochemically 

anomalous concentrations of gold, silver, and zinc in rock 

chip samples from the area (Davis, 1983). The nearest 

historical claim was located for placer gold in 1906 along 

the John Day River, about 16 mi north of the study areas.

The lower part of the John Day River has had little 

mining-related activity. Gold placers were worked in the 

upper John Day River basin in the 1850's, centered near 

Canyon City, 85 mi southeast of the study areas. Records 

are incomplete, but earliest reported production was in 

1852 (Brooks and Ramp, 1968). By 1864, placer gold was 

being mined in the Spanish Gulch mining district, on a 

tributary of the John Day River, 60 mi southeast of the 

study areas. Gold and silver were also found in quartz 

veins and silicified zones in the district.

Other metals have been mined south of the study areas 

from mineralized zones in Eocene and earliest Oligocene(?) 

volcanic and volcaniclastic rocks of the Clarno formation. 

The Ashwood mining district, about 30 mi southwest of the 

study areas, produced silver, gold, copper, and lead valued 

at the time at more than $530,000, mainly from the Oregon 

King mine, between 1899 and 1965. The Horse Heaven 

mine, about 30 mi south of the study areas, produced

17,216 flasks of mercury between 1934 and 1958, when the 

deposit was mined out (Brooks, 1971).

Petroleum leases cover the study areas and the surrounding region. Three wells were drilled near Clarno 

between 1929 and 1957 (Davis, 1983); one had a gas show, 

but none contained oil or commercial quantities of gas. An 

additional dry hole (Standard Kirkpatrick No. 1) was 

drilled near Condon in 1957 to a depth of 8,726 ft.

Sand, gravel, and stone have been quarried from at 

least 13 sites along State and Federal highways between 6 

and 30 mi from the study areas. Most is used as fill or as 

a base or topping for roads. Sites are reopened or new sites 

are developed as needs arise. Supplies of stone, sand, and 

gravel outside the study areas are more accessible and are 

ample to supply regional demand.

Appraisal of Mineral Resources

Although no evidence of mining activity was found, 

production of both placer and lode gold in upper parts of 

the John Day River basin and small-scale placer mining 

along the Columbia River suggest that gold may be present 

in fluvial gravels within the study areas. Preliminary 

sampling of seven gravel bars confirmed the presence of 

gold (Campbell and McHugh, 1987).

Five gravel bars in the Lower John Day Wilderness 

Study Area were sampled for placer gold. Each of the 10 

samples collected contains tiny flakes of gold less than 

0.008 in. across. Estimated average gold content for individual bars ranges from 0.00004 to 0.0007 troy oz/yd3. 

Estimated gravel volumes ranged from 150,000 to 260,00 

yd3 . Total gravel volume in the five bars is estimated at 1.0 

million yd3 and averages 0.0004 troy oz/yd3 gold ($0.17/yd3 

at a gold price of $400/ troy oz).

Two gravel bars in the southern part of the Thirtymile 

Wilderness Study Area contain an estimated 790,000 yd3 of 

inferred subcconomic resources averaging 0.003 troy oz/ 

yd3 gold ($1.20/yd3) (fig. 2). Samples from these bars 

contain considerably more gold than those from gravel in 

the Lower John Day Wilderness Study Area. Because of 

the reconnaissance nature of the alluvial samples, the significance of this apparent difference in gold content of bars 

between the two study areas is unknown. However, 

backflooding up the John Day River from the catastrophic 

Lake Missoula and Lake Bonneville floods may have affected the distribution of gold in river sediments.

Volumes were estimated for 21 other gravel bars in the 

Lower John Day Wilderness Study Area (4.8 million yd3) 

and 9 other bars in the Thirtymile Wilderness Study Area 

(1.7 million yd3). Results from the sampled sites suggest 

an overall gold content of 0.0016 troy oz/yd3 (or $0.64/yd3) 

for gravel in the study areas.

Alluvium samples were collected for reconnaissance 

purposes during this study, so only preliminary estimates of

Mineral Resources of the Lower John Day and Thirtymile Wilderness Study Areas, Oregon AS
volume and grade could be made. The bar with the highest 

estimated grade contains about $1.4 I/yd3 at a gold price of 

$400/troy oz. For this bar, mining operations would approach feasibility with gold contents of approximately 

$3.80/yd3 (Campbell and McHugh, 1987). The estimated 

grade would be valued at $3.80/yd3 if gold increased in 

value to $1080/troy oz. For other gravel bars within the 

study areas, mining costs would be somewhat higher due to 

more difficult access.

Lode samples of basalt taken from an abandoned 

mining claim and from an area with anomalous metal 

concentrations, as reported by Davis (1983), contain no 

metal concentrations of economic significance.

ASSESSMENT OF MINERAL RESOURCE 

POTENTIAL

By Jay A. Ach, Scott A. Minor, James G. Frisken, and 

Richard J. Blakely 

U.S. Geological Survey

Geology

The Lower John Day and Thirty mile Wilderness Study 

Areas are located in the southern part of the Columbia 

Plateau physiographic province, which is characterized by 

an extensive sequence of gently north-tilted Miocene basalt 

flows of the Columbia River Basalt Group (Swanson and 

others, 1981; Walker, 1977). Less than 100 mi southeast of 

the study area, the Columbia Plateau terminates against the 

Blue Mountains, an uplifted block containing Mesozoic 

volcanic-arc basement rocks (Brooks and Vallier, 1978). 

The active Cascades volcanic arc bounds the southwest side 

of the province about 50 mi west of the study area. South 

of the study area, flows of the Columbia River Basalt 

Group are primarily underlain by Eocene and Oligocene 

volcanic and volcaniclastic rocks that, in turn, overlie 

Mesozoic marine sedimentary rocks. The Columbia River 

Basalt Group in the region was locally folded and faulted, 

primarily during the Miocene and Pliocene.

Only basalt flows of the Columbia River Basalt Group 

(Swanson and others, 1981) are exposed in the study areas 

(fig. 2). However, older rocks are exposed upriver to the 

south. The oldest rocks exposed nearby in the region are 

those of the Eocene and earliest Oligocene(?) Clarno Formation (Merriam, 1901a; G.W. Walker, oral commun., 

1987), which crop out approximately 20 mi south of the 

study areas. The Clarno Formation consists predominantly 

of interfingering andesite flows, domes, plugs, and breccias 

and associated volcaniclastic and tuffaceous rocks.

The John Day Formation (Merriam, 1901b) unconformably overlies the Clarno Formation and is exposed in 

the John Day River canyon 7 mi south of the study areas

(Swanson, 1969; Robinson, 1975; Swanson and others, 

1981). The age of the John Day Formation ranges from 

about 37 Ma (million years before present) to about 19 Ma, 

latest Eocene to early Miocene (G.W. Walker, oral commun., 1987). The John Day Formation near the study areas 

consists of intercalated tuffs, tuffaceous sedimentary rocks, 

and mafic lava flows. Geologic evidence suggests that 

both the John Day and Clarno Formations, which have a 

combined thickness of several thousand feet where exposed, extend northward underneath the study areas. This 

is also suggested by data from the Standard Kirkpatrick No. 

1 test hole (Fox and Reidel, 1987), 14 mi east of the study 

areas (fig. 1). The hole penetrated 2,440 ft of rocks of the 

Columbia River Basalt Group before it passed through 

4,255 ft of John Day and possibly Clarno rocks. This also 

suggests that the base of the Columbia River Basalt Group 

may only be a few hundred feet below river level at the 

south end of the Thirtymile Wilderness Study Area.

Flows of the Columbia River Basalt Group form the 

bedrock throughout the study areas. The maximum exposed thickness of the basalts in the study areas is about 

1,800 ft, equivalent to the maximum depth of the John Day 

River canyon. The dark-gray to black Columbia River 

Basalt flows typically range in thickness from 50 to 100 ft 

and are conspicuously columnar jointed. The upper parts 

of the flows are usually vesicular and readily erode into 

ledges, whereas the denser, more resistant middle and 

lower parts of the flows form prominent cliffs. Such topographic expression of the subhorizontal flows results in 

"stair-step" topography along the canyon walls. Interflow 

layers of tuffaceous rocks occur only locally in the sequence and rarely exceed 10 ft in thickness.

Swanson and others (1981) divided rocks of the Columbia River Basalt Group in the study areas into two 

formations following earlier stratigraphic nomenclature 

(Swanson and others, 1979). The oldest formation, the 

Grande Ronde Basalt, forms most of the bedrock within the 

study areas. The Grande Ronde Basalt is at least 1,400 ft 

thick in the study areas; its base is not exposed. The 

overlying Frenchman Springs Member of the Wanapum 

Basalt caps the rim of the John Day River canyon and thus 

is only locally exposed in outlying parts of the study areas. 

The Wanapum Basalt has a maximum exposed thickness of 

about 250 ft in the study areas. The Grande Ronde flows 

are generally aphyric, whereas many of the Wanapum 

flows in the study areas contain conspicuous clusters of 

plagioclase phenocrysts and are medium grained (Swanson 

and others, 1981). The Grande Ronde Basalt has potassium-argon ages ranging from 16.5 to 14 Ma (Watkins and 

Baksi, 1974) and stratigraphy indicates that the overlying 

Wanapum Basalt is older than 12 Ma (Swanson and others, 

1979).

In the study areas, there is abundant geomorphic evidence of older, less entrenched channels of the John Day

A6 Mineral Resources of Wilderness Study Areas: John Day Region, Oregon
River, the most obvious of which are several meander scars 

perched along the canyon walls as high as 500 ft above the 

present river level. Erosional remnants of river alluvium 

deposited in these older channels mantle the meander scars 

in some places. Active and recent alluvium in the study 

areas consists primarily of point-bars of sand and gravel 

blanketing the inside banks of the John Day River meanders. Talus aprons and cones composed of basalt debris are 

found at the bases of most of the large cliffs along canyon 

walls. On the plateau surrounding the study areas, loess, 

deposited by Pleistocene winds, is a major component of 

soils.

The area occupied by the Columbia Plateau was probably the location of a broad northeast-trending basin that 

developed within the Mesozoic continental margin during 

the Early Cretaceous. This basin subsided as sediment and 

volcanic material (including flows of the Columbia River 

Basalt Group) accumulated throughout the Tertiary, forming the Columbia Basin (Fritts and Fisk, 1985a). Uplift of 

the Blue Mountains, at the south end of the Columbia 

Plateau, began in the Eocene during deposition of the 

Clarno Formation and continued for the remainder of the 

Tertiary (Fox and Reidel, 1987). Angular unconformities 

separate rocks of the Clarno Formation, John Day Formation, and Columbia River Basalt Group (Swanson, 1969; 

Robinson, 1975), suggesting that uplift of the Blue Mountains and subsidence of the Columbia Basin continued 

during the Oligocene and early Miocene. Entrenchment of 

the meandering John Day River into its canyon and the 

perched meander scars in the canyon suggest that northward tilting of the southern part of the Columbia Plateau, 

subsidence of the central part of the plateau, or both continued intermittently into the Quaternary.

In an overall sense, flows of the Columbia River Basalt 

Group underlying the study areas form a gently northwardtilted (less than 5°) homocline. Some high-angle obliqueslip faults and minor normal faults cut the homocline, primarily near the northern part of the Lower John Day Wilderness Study Area (Swanson and others, 1981). The 

normal faults strike either northwest or north-northwest; the 

oblique-slip faults all strike northwest. A north-northweststriking normal fault near the south end of the Thirtymile 

Wilderness Study Area forms the northernmost part of a 

complex, north-trending zone of deformation that extends 

several miles south of the study area into the North Pole 

Ridge Wilderness Study Area (Minor and others, 1988). 

Several east- to northeast-trending gentle, open folds are 

present in the region, particularly southeast of the study 

areas (Swanson and others, 1981). Some of these folds are 

cut by faults, subparallel to the fold axes, that appear to be 

genetically related to the folds.

Faulting and folding on the Columbia Plateau, which is 

attributed primarily to regional north-south compression, 

was most active between about 11 and 3 Ma (Bela, 1982).

Much of the tilting and subsidence of the southern part of 

the plateau was approximately coeval with this deformation.

The late Pleistocene catastrophic Lake Missoula floods 

that cut the Channeled Scablands in central Washington 

also caused backflooding that flowed up the John Day 

River. Earlier backflooding related to the Lake Bonneville 

flood may also have affected the John Day River. Geomorphic evidence at the confluence of the John Day and Columbia Rivers indicates that at least one of the Lake Missoula floods overtopped landforms at an elevation of 956 ft 

above sea level. This backflooding carried sediments ranging from silt to cobbles(?) upstream through both study 

areas, and floodwaters possibly reached elevations of over 

1,000 ft above sea level (Bretz, 1969).

Geochemical Studies

A reconnaissance geochemical investigation of the 

study areas was made using samples of rock, water from 

springs, stream sediment, and the nonmagnetic fraction of 

heavy-mineral concentrates from stream sediments. The 

stream-sediment and concentrate samples contain material 

derived from alluvium and rock units of the drainage basins 

within the study areas. Sampled drainage basins range in 

area from less than one to several square miles.

From the two study areas, 45 rock samples, 42 streamsediment samples, and 42 heavy-mineral-concentrate 

samples were analyzed for 31 elements by six-step 

semiquantitative emission-spectrographic methods (Myers 

and others, 1961; Grimes and Marranzino, 1968). Additional analyses for arsenic, antimony, bismuth, cadmium, 

and zinc were made using inductively coupled argon 

plasma-atomic emission spectroscopy (Crock and others, 

1987). Samples were analyzed for gold by an atomicabsorption method (Thompson and others, 1968) and a 

graphite furnace/atomic-absorption method that has a lower 

detection limit of 0.002 parts per million (ppm) (Meier, 

1980). Analyses for mercury by the method of Koirtyohann and Khalil (1976) and for uranium and thorium by 

methods described by Millard (1976) and Centanni and 

others (1956) were also performed. Three samples of water 

from springs were analyzed for uranium using a method 

described by Scintex Corporation (1978). Complete analytical data and a description of sampling techniques, 

sample preparation, and analytical methods were provided 

by Adrian and others (written commun., 1987).

Analyses of stream-sediment and heavy-mineral-concentrate samples are used to identify drainages that have 

anomalously high concentrations of metallic and metalrelated elements. Rock samples were collected from any 

areas of altered bedrock and from each lithologic unit to

Mineral Resources of the Lower John Day and Thirtymile Wilderness Study Areas, Oregon A7
obtain information on trace-element signatures associated 

with potentially mineralized areas and to provide data on 

background trace-element concentrations. For this study, 

anomalous geochemical values are considered to be those 

that either exceed by a factor of three the mean concentration in basalt samples collected from the region or exceed 

three times the average concentration in basalt (Levinson, 

1974).

Data from stream-sediment and heavy-mineral-concentrate samples show only a few scattered, mostly singleelement anomalies. Elements found in anomalous concentrations are gold, lead, tin, and bismuth. Stream-sediment 

and heavy-mineral-concentrate sample media from the 

study areas are not considered as reliable as in most other 

areas, the reason being contamination from older, perched 

alluvium and from alluvium deposited by catastrophic Lake 

Missoula- and Lake Bonneville-related flooding. Perched 

alluvium, deposited by a younger John Day River, is 

common at many levels within the canyon as high as 500 

ft above current river level. Flooding due to catastrophic 

lake release may have deposited alluvium from outside 

present drainages in the John Day River canyon to levels of 

over 1,000 ft above sea level (Bretz, 1969). Present-day 

tributary streams that enter the John Day canyon cut 

through both the older alluvium and the flood-deposited 

alluvium. These materials may be contained in active alluvium of the streams. Loess from the surrounding plateau 

might also be added to the alluvium by either runoff or 

wind. This resulting alluvial mix therefore does not solely 

represent the bedrock within the sampled drainage basin. 

The anomalies noted in stream-sediment and heavy-mineral-concentrate samples are therefore difficult to ascribe to 

a single source. The gold is most likely alluvial in nature 

and not derived locally. Lead shot is found in some of the 

samples that contain lead anomalies, indicating that contamination is a likely source of those anomalies. Tin is 

associated with lead in the concentrates and could be a 

cocontaminant. With the exception of gold, these anomalies are low, single element, and scattered. This suggests 

that they would not indicate significant mineral resource 

potential even if contamination by older alluvium, flood 

alluvium, loess, or human activities was not a problem.

Analyses of rock samples from the study areas provide 

the best basis for a geochemical survey because they are 

resistant to contamination by alluvium or humans. Analyses of rocks from the study areas revealed no anomalies in 

the Thirtymile Wilderness Study Area and only a single 

anomaly each for lead (200 ppm), mercury (0.19 ppm), and 

zinc (350 ppm) in the Lower John Day Wilderness Study 

Area. These anomalies are from scattered locations, are 

low and single element, and therefore are not of great 

significance.

In the Geology, Energy, and Minerals (GEM) reconnaissance of the study area (Davis, 1983), low-level geochemical anomalies are reported for rock samples from 

both areas. In samples from the southern part of the Thirtymile Wilderness Study Area, there is one anomaly each 

of gold (0.02 ppm, the lower limit of detection for that 

study), mercury (0.58 ppm), and uranium (5.4 ppm). Three 

other samples have mercury concentrations between 0.10 

and 0.20 ppm. The 0.02 ppm gold content is probably not 

anomalous because the concentration is at the detection 

limit of the method used and therefore not completely 

accurate, and because this concentration is only slightly 

more than typical concentrations (as much as 0.011 ppm 

gold) for the Columbia River Basalt Group (Gottfried and 

others, 1972). Six GEM samples from the Lower John Day 

Wilderness Study Area contain low levels of mercury (0.10 

to 0.17 ppm). The fact that 10 of 12 rock samples in the 

GEM study have mercury concentrations of 0.10 ppm or 

more, whereas only 1 of 45 of the samples collected by the 

U.S. Geological Survey for the current study contains 

mercury at these concentrations, suggests that either the 

GEM analyses or the U.S. Geological Survey analyses are 

incorrect. Quality control in U.S. Geological Survey laboratories is usually good, suggesting that the GEM analyses 

may have given concentrations higher than are actually 

present, but there are not enough data to determine absolutely which set of analyses is correct. Assuming the GEM 

analyses are correct, the gold and mercury anomalies might 

be evidence of either epithermal mercury or epilhermal 

gold deposits, but the likelihood of the occurrence of either 

of these types of deposit is remote because unaltered basalt 

is not usually a suitable host rock for such deposits. Epilhermal deposits are marked by zones of pervasive hydrothermal alteration; no traces of such alteration were found in 

fault zones or elsewhere within the study area. Faulting, 

necessary to provide fluid pathways for the formation of 

hydrothermal deposits, is minimal in the area where the 

anomalies occur.

Geophysical Studies

Magnetic, gravity, and radiometric data from northcentral Oregon were compiled and examined to aid assessment of the mineral resource potential of Lower John Day 

and Thirtymile Wilderness Study Areas. The sparsely 

distributed nature of all three data sets is adequate for 

examining the regional structural and tectonic setting of the 

study areas, but it does not permit assessment of mineral 

resource potential at the scale of individual deposits except 

in areas located directly beneath detailed profiles.

Magnetic Data

The only publicly available aeromagnetic data collected from the study areas were compiled under contract to 

the U.S. Department of Energy as part of the NURE proAS Mineral Resources of Wilderness Study Areas: John Day Region, Oregon
gram (High Life Helicopters, Inc./QEB, Inc., 1981). These 

data were collected at an average of 400 ft above the terrain 

along east-west flightlines spaced 6 mi apart and northsouth flightlines spaced 24 mi apart. Only three NURE 

flightlines actually crossed the study areas; these were 

directed approximately east-west at latitudes 45° 12' N., 

45° 17' N., and 45°22' N. Anomalies within the study areas 

are characterized by short wavelengths (500 to 8,000 ft), 

high amplitudes (100 to 2,000 nanotesla, nT), and high 

gradients (1 to 4 nT/ft). Unmetamorphosed basaltic rocks, 

such as the Miocene basalt flows exposed throughout the 

study areas, commonly have high magnetic susceptibilities 

and high remanent magnetizations. In aeromagnetic profiles constructed from the data of low-altitude flights, such 

rocks typically show high-amplitude, short-wavelength 

magnetic anomalies that often obscure anomalies caused by 

deeper magnetic sources. Some of the individual highs and 

lows along the magnetic profiles may indicate mineralized 

areas, but they are more likely the result of lateral variations in the abundance and characteristics of magnetite 

grains in shallow basaltic rocks.

The northernmost NURE flightline (latitude 45°22' N.) 

crossed the northern part of the Lower John Day Wilderness Study Area. The resulting profile shows a longwavelength anomaly superimposed on the short-wavelength anomalies described above. The long-wavelength 

anomaly is negative in sign, approximately 1,500 nT in 

amplitude, approximately 4 mi in width, and centered 

around latitude 45°22' N. in the Lower John Day Wilderness Study Area. The horizontal gradient and general 

shape of the anomaly indicate that it is caused by a source 

located at shallow depth. The anomaly is located in an area 

of minor deformation, as demonstrated by mapped normal 

faults (fig. 2). The decreased magnetic intensity of the 

anomaly may be caused by pervasive alteration (and consequent reduction of magnetic susceptibility and remanent 

magnetization) of the volcanic rocks associated with the 

deformation, but no alteration was observed in this area. 

Alternatively, the anomaly may be caused by a buried 

intrusion of silicic composition. Silicic intrusive rocks 

typically have lower susceptibility and remanent magnetization than basaltic volcanic rocks. No silicic igneous 

rocks are exposed within the study areas, but silicic intrusive rocks of Tertiary age crop out 40 mi southwest of the 

anomaly (Swanson, 1969); similar rocks of Oligocenc age 

were recovered from the Standard Kirkpatrick No. 1 well 

located 14 mi east of the study areas (Fox and Reidel, 

1987).

A regional compilation of aeromagnetic data (Committee for the Magnetic Anomaly Map of North America, 

1987) shows a linear magnetic depression extending the 

entire length of the two study areas. The NURE magnetic 

profiles were the only magnetic data available for this part 

of Oregon. The linear anomaly evident in these regional

profiles probably reflects a highly smoothed version of the 

negative anomaly discussed in the previous paragraph.

Gravity Studies

Gravity data from the vicinity of Lower John Day and 

Thirtymile Wilderness Study Areas were obtained from the 

National Geophysical Data Center of the National Oceanic 

and Atmospheric Administration in Boulder, Colo. Gravity 

measurements are scattered at a 3- to 6-mi spacing in this 

region, and none are actually within the study areas. 

Observed gravity measurements, based on the International 

Gravity Standardization Net datum (Morelli, 1974), were 

reduced to free-air anomalies using standard formulas 

(Telford and others, 1976). Bouguer, curvature, and terrain 

corrections (out to a distance of 103.6 mi from each station) 

at a standard reduction density of 2.67 grams per cubic 

centimeter (g/cm3) were added to the free-air anomaly at 

each station to determine complete Bouguer gravity anomalies.

Bouguer anomalies typically reflect shallow density 

contrasts of interest in resource appraisals, but they also 

include contributions from deep-crustal masses that correlate with topography in a manner consistent with the concept of isostasy. To reduce the effect of deep sources 

related to isostasy, an isostatic residual-gravity map was 

constructed. The map was constructed from the Bouguer 

gravity data by removing a regional gravity field computed 

from a model of the crust-mantle interface that assumes 

Airy-type isostatic compensation (Jachcns and Griscom, 

1985). A regional perspective of the gravitational setting of 

the area can be seen on Jachens and others (1985).

The sparse distribution of gravity measurements precludes a detailed analysis of mass distribution within and 

adjacent to the study areas, but it is sufficient to illuminate 

the regional tectonic and structural setting of the area. The 

Lower John Day and Thirtymile Wilderness Study Areas 

lie on the northern edge of a positive isostatic residual 

anomaly. The anomaly is 20 milligals (mGal) higher in 

amplitude than surrounding areas, has lateral dimensions of 

approximately 15 mi east-west and 30 mi north-south, and 

forms part of a 250-mi-long chain of anomalies that trends 

northeast through northern Oregon and southeastern Washington. Riddihough and others (1986) noted that this lineament is on-strike with similar gravity features in the 

Klamath Mountains and suggested that it reflects a preTcrtiary continental boundary extending across north-central Oregon and southeastern Washington.

Radiometric Data

Radiometric data were collected as part of the NURE 

survey (High Life Helicopters, Inc./QEB, Inc., 1981). 

Recordings were made of gamma-ray flux from radioactive

Mineral Resources of the Lower John Day and Thirtymile Wilderness Study Areas, Oregon A9
isotopes of potassium, thorium, and uranium along eastwest flightlines spaced approximately 6 mi apart and at an 

average altitude of 400 ft above the terrain. Only three 

flightlines actually crossed the study areas. Count rates 

were low during all three flights and no anomalous radiation was detected. However, because only three flightlines 

crossed the study area and because gamma rays are 

strongly attenuated by passage through earth materials, 

these data do not preclude the presence of anomalous 

amounts of radioactive elements away from the flightlines 

or buried a few feet or more beneath the surface.

Conclusions

The short-wavelength, high-amplitude magnetic 

anomalies observed in profiles derived from the data of 

low-altitude flights over the study areas are typical for this 

region. They arc caused principally by variations in abundance and characteristics of magnetite in the unmetamorphosed basalt flows exposed throughout the area. However, a possible magnetic source located beneath the topographic surface was detected in one east-west profile at 

latitude 45°22' N. The source may be a buried silicic intrusion, which may have had local hydrothermal phenomena associated with it, but there may be other explanations 

for the anomaly. Gravity and radiometric data neither 

indicate nor preclude the presence of mineralization within 

the study areas.

Mineral and Energy Resource Potential of the 

Lower John Day Wilderness Study Area

Mineral Resource Potential

Investigations by the U.S. Geological Survey and the 

U.S. Bureau of Mines indicate that the Lower John Day 

Wilderness Study Area has low mineral resource potential, 

certainty level C, for placer gold in scattered, small river 

bars of alluvium located in the canyon of the John Day 

River.

Stream-sediment samples collected by the U.S. Geological Survey for this study and by the U.S. Bureau of 

Mines (Campbell and McHugh, 1987) indicate that active 

alluvium in the John Day River and its tributaries contains 

small quantities of placer gold. Older perched alluvium 

also may contain similar small quantities of gold, but these 

perched river bars were not sampled. The chance that any 

alluvium within the study area contains significant gold 

deposits is considered remote. A certainty level of C is 

assigned because a significant number of samples were 

analyzed and their gold contents were uniformly low.

The magnetic low indicated by geophysical surveys in 

the northern part of the study area could indicate the existence of a shallow-level silicic pluton. Hydrothermal systems associated with such plutons may produce epithermal

mineral deposits. If this pluton does indeed exist, however, 

it is probably of an age similar to that of the rhyolite pluton 

found in the Standard Kirkpatrick No. 1 hole, 14 mi to the 

east. That pluton was dated at 28.8 Ma, late Oligocene 

(Fox and Reidel, 1987). A pluton of this age would have 

been emplaced in rocks of the John Day Formation and 

would predate the middle Miocene Columbia River Basalt 

Group. This precludes the pluton from having provided a 

source of heat to drive a hydrothermal system within the 

overlying Columbia River Basalt Group. The absence of 

geochemical anomalies in the area of the magnetic anomaly 

and the absence of any visible alteration in the area suggest 

that significant hydrothermal alteration has not occurred in 

this area. Therefore, the chance that epithermal mineral 

deposits formed is extremely remote.

Small deposits of sand and gravel suitable for construction use are present in the study area but are too small 

to constitute a resource. No undiscovered sand and gravel 

resources are likely to be found beyond known deposits.

Energy Resource Potential

Investigations by the U.S. Geological Survey indicate 

that the Lower John Day Wilderness Study Area has low 

resource potential for petroleum and natural gas, certainty 

level B. The study area has no geothermal resource potential, certainty level D.

Central Oregon has been explored for oil since the 

1930's, but no economic discoveries of oil or gas have been 

made (Thompson and others, 1984). Exploration efforts 

and petroleum resource appraisals are hampered by the 

meager data available on subsurface geology in central 

Oregon (Thompson and others, 1984; Fritts and Fisk, 

1985a, b). Few deep wells have been drilled, outcrops of 

pre-Ccnozoic rocks are rare, and thick Cenozoic volcanic 

cover causes difficulty in the interpretation of geophysical 

data (Newton, 1974). Additionally, the region is structurally complex and has Cenozoic structures that differ from 

underlying Mesozoic structures. Little is known about preMcsozoic structures (G.W. Walker, oral commun., 1987).

The primary exploration targets in central Oregon have 

been within two Cretaceous basins (Newton, 1968; Frills 

and Fisk, 1985a, b). The larger and older of the basins is 

the Columbia River Basin of middle lo Late Cretaceous age 

(Newton, 1966,1977; Fritts and Fisk, 1985a, b). The study 

area is in the southwestern part of this basin (Frills and 

Fisk, 1985a, b). The smaller and slightly younger (latest 

Cretaceous) Ochoco Basin lies to the soulh and never extended as far north as the study area (Thompson and others, 

1984).

Oil and gas leases cover the entire study area. Four 

tesl holes were drilled near the study area between 1929 

and 1957; three of these are near Clarno, 22 mi to the south, 

and one is near Condon, 14 mi to ihe easl. The holes near

A10 Mineral Resources of Wilderness Study Areas: John Day Region, Oregon
Clarno indicate that pre-Tertiary rocks are overlain by 

2,870 to 4,000 ft of rocks of the Tertiary-age John Day and 

(or) Clarno Formations. One hole near Clarno, the Clarno 

Basin Oil Company's Burgess No. 2, had a gas show, 

presumably from Cretaceous-age rocks. Asphalt-bearing 

geodes have also been found near Clarno (Collier, 1914; 

Buwalda, 1921). Well logs for all holes are on file at the 

Oregon Department of Geology and Mineral Industries in 

Portland, Oreg.

The best studied and documented hole in the region is 

Standard Oil Company's Kirkpatrick No. 1, located near 

Condon (fig. 1). From the surface, this hole penetrated 

2,440 ft of the Columbia River Basalt Group. Between 

depths of 2,440 and 6,135 ft, the hole passed through volcanic and sedimentary rocks of the John Day Formation. 

Volcanic and sedimentary rocks of either the John Day or 

Clarno Formation were encountered between depths of 

6,135 and 6,695 ft. The interval from 6,695 ft to the bottom of the hole at 8,726 ft was through Mesozoic sedimentary rocks, primarily argillite but including some graywacke and siltstone (Fox and Reidel, 1987). Although the 

Mesozoic sedimentary rocks are thermally mature (Newton, 1979; Summer and Verosub, 1987), the total organic 

content of these rocks is low to very low (Brown and Ruth 

Laboratories, 1983; Fox and Reidel, 1987). Most of the 

organic material present is of terrestrial origin, and is 

hydrogen poor and gas prone (Brown and Ruth Laboratories, 1983).

For purposes of an oil and gas resource potential assessment, it is assumed that the subsurface stratigraphy of 

the wilderness study area is similar to that in the Standard 

Kirkpatrick No. 1 hole. The study area does lie within the 

Cretaceous Columbia River Basin. The Mesozoic rocks are 

primarily argillites but include some graywackes and 

siltstones, lithologies usually having low porosity, thereby 

limiting their potential as reservoir rocks. Their lack of 

potential as source rocks is indicated by their low total 

organic content. Although these Mesozoic rocks have been 

determined to be thermally mature, local rhyolite intrusions 

(Fox and Reidel, 1987) may have produced intense local 

heating, thereby degrading or driving off nearby hydrocarbons. An analysis of organic carbon from the Standard 

Kirkpatrick No. 1 hole (Brown and Ruth Laboratories, 

1983) suggests that if hydrocarbons are present, they are 

more likely to occur as gas than oil. Fouch (1983) rated the 

study area as having "low potential" for oil and gas. Fox 

and Reidel (1987) considered the area around the Standard 

Kirkpatrick No. 1 well to have "marginal hydrocarbon 

potential." However, Davis (1983) considered the study 

area to have "moderate potential for hydrocarbons." Given 

the probable lack of both suitable source and reservoir 

rocks and the possible local overheating, the likelihood of 

the occurrence of oil and gas in the study area is not great, 

and so, under the definitions used in this study, the area is

given a low resource potential for oil and gas. A certainty 

level of B is assigned because of the absence of any subsurface data, either seismic or drill hole, from within the 

study area. The stratigraphy in the nearest drill holes, 14 

to 22 mi away, may differ from that of the study area, and 

more favorable source and reservoir rocks could exist 

beneath the study area. The lack of available seismic data 

precludes any knowledge of structure or potential traps 

beneath the study area.

The study area has no resource potential for geothermal energy, certainty level D. The study area contains no 

hot springs or warm springs (Bliss, 1983) and previous 

regional geothermal surveys have not indicated any geothermal resource potential for the area (Bowen and others, 

1978; Riccio, 1978; Muffler, 1979; National Geophysical 

Data Center, 1982; Reed, 1983; Bliss, 1983). Additionally, 

the study area lies within a small area that has lower heat 

flow than the rest of eastern Oregon and Washington 

(Nathenson and others, 1983).

Mineral and Energy Resource Potential of the 

Thirtymile Wilderness Study Area

Mineral Resource Potential

Investigations by the U.S. Geological Survey and the 

U.S. Bureau of Mines indicate that the Thirtymile Wilderness Study Area has low mineral resource potential for 

placer gold in scattered, small alluvial deposits, certainty 

level C. The study area also has low mineral resource 

potential, certainty level C, for gold and mercury in epithermal deposits.

A low resource potential exists for gold in placer 

deposits in the canyon of the John Day River. Streamsediment samples collected by the U.S. Geological Survey 

and the U.S. Bureau of Mines (Campbell and McHugh, 

1987) show that active alluvium in the John Day River and 

its tributaries contains small quantities of gold, locally 

reaching subeconomic concentrations. Older perched alluvium may also contain similar small quantities of gold, but 

these deposits were not sampled. The chance that any 

alluvium within the study area contains significant gold 

deposits is considered remote. A certainty level of C is 

assigned because a significant number of samples were 

analyzed, and gold, when present, was found in only low 

concentrations. Some gravel bars sampled by the U.S. 

Bureau of Mines contain gold in subeconomic quantities. 

A slight chance exists that further sampling would reveal a 

bar with economic quantities of gold.

The southern part of the Thirtymile Wilderness Study 

Area has low mineral resource potential for gold and (or) 

mercury in epithcrmal deposits, certainty level C. Several 

low-level mercury anomalies and one low-level gold anomMineral Resources of the Lower John Day and Thirtymile Wilderness Study Areas, Oregon A11
aly in rock sample data reported in the GEM study (Davis, 

1983) are the sole basis for this potential. The accuracy of 

these data is not certain. Rock samples collected by both 

the U.S. Geological Survey and U.S. Bureau of Mines from 

the same area do not contain anomalous concentrations of 

either mercury or gold. Permeability of the rocks is an 

important prerequisite for the emplacement of epithermal 

mercury deposits (Brooks, 1963) and epithermal gold deposits. The Columbia River Basalt Group flows generally 

lack permeability and therefore are unlikely host rocks for 

epithermal deposits, although faults, vesicular flow tops, or 

contacts between successive flows might provide some 

limited fluid pathways. However, no hydrothermal alteration, diagnostic of epithermal mineralization, was observed 

within fault zones or elsewhere within the study area. 

Brooks (1963) observed the notable lack of mineral deposits within the Columbia River basalts and characterized 

them as "remarkably unmineralized." A certainty level of 

C is assigned because the only evidence of epithermal 

deposits is not only scanty, but also questionable.

Small sand and gravel deposits suitable for construction use are present in the study area but are too small to 

constitute a resource. Other suitable deposits occur outside 

the study area and closer to potential markets. No undiscovered sand and gravel resources are likely to be found 

beyond known deposits.

Energy Resource Potential

The investigations by the U.S. Geological Survey 

indicate that the Thirtymile Wilderness Study Area has low 

resource potential for petroleum and natural gas, certainty 

level B. Oil and gas leases cover the study area. The study 

area has no geothermal resource potential, certainty level 

D.

The study area lies within the Cretaceous Columbia 

River Basin. Mesozoic rocks are unexposed in the study 

area but are assumed to be similar to those in the Standard 

Kirkpatrick No. 1 hole, 14 mi to the east. The Mesozoic 

rocks found in this drill hole have limited potential as either 

source or reservoir rocks. Although the rocks have been 

determined to be thermally mature, they may have undergone intense local heating, thereby degrading or driving off 

any nearby hydrocarbons. If hydrocarbons are present, 

they are more likely to be gas than oil. Fouch (1983) rated 

the study area as having low potential for oil and gas. Fox 

and Reidel (1987) considered the area around the Standard 

Kirkpatrick No. 1 well to have "marginal hydrocarbon 

potential." However, Davis (1983) considered the study 

area to have moderate potential for hydrocarbons. Given 

the possible lack of both suitable source and reservoir rocks 

and the possible local overheating, the likelihood of oil and 

gas occurring in the study area is not great. Under the 

definitions used in this study, the area is given a low resource potential for oil and gas. See previous discussion in 

the "Energy Resource Potential" section for the Lower John 

Day Wilderness Study Area. A certainty level of B is 

assigned because no subsurface data, either seismic or drill 

hole, were available for the study area. The stratigraphy in 

the nearest drill holes, 14 and 18 mi away, may differ from 

that of the study area and more favorable source and reservoir rocks could exist beneath the study area. The lack of 

seismic data precludes any knowledge of structure or potential traps beneath the study area.

The study area has no resource potential for geothermal energy, certainty level D. The study area contains no 

hot springs or warm springs (Bliss, 1983) and previous 

regional geothermal surveys have not indicated any geothermal resource potential for the area (Bowen and others, 

1978; Riccio, 1978; Muffler, 1979; National Geophysical, 

Data Center, 1982; Reed, 1983; Bliss, 1983). Additionally, 

the study area lies within a small area that has lower heat 

flow than the rest of eastern Oregon and Washington 

(Nathenson and others, 1983).

REFERENCES CITED

Bcla, J.L., 1982, Geologic and neotectonic evolution of northcentral Oregon: The Dalles 1° by 2° quadrangle: Oregon 

Department of Geology and Mineral Industries Geological 

Map Series GMS-27, scale 1:250,000, 2 sheets.

Bliss, J.D., 1983, Oregon Basic data for thermal springs and 

wells as recorded in GEOTHERM: U.S. Geological Survey 

Open-File Report 83-435, 342 p.

Bowen, R.G., Peterson, N.V., and Riccio, J.F., 1978, Low- to 

intermediate-temperature thermal springs and wells in Oregon: Oregon Department of Geology and Mineral Industries 

Geological Map Series GMS-10, scale 1:500,000.

Bretz, J.H., 1969, The Lake Missoula floods and the Channeled 

Scabland: Journal of Geology, v. 77, p. 505-543.

Brooks, H.C., 1963, Quicksilver in Oregon: Oregon Department 

of Geology and Mineral Industries Bulletin No. 55, 223 p.

 1971, Quicksilver deposits in Oregon: Oregon Department of Geology and Mineral Industries Miscellaneous Paper 

15, map, scale 1:1,000,000.

Brooks, H.C., and Ramp, L., 1968, Gold and silver in Oregon: 

Oregon Department of Geology and Mineral Industries Bulletin 61, 337 p.

Brooks, H.C., and Vallier, T.L., 1978, Mesozoic rocks and tectonic evolution of eastern Oregon and western Idaho, in 

Howell, D.G., and McDougall, K.A., eds., Mesozoic paleogeography of the western U.S.: Pacific Section, Society of 

Economic Paleontologists and Mineralogists Pacific Coast 

Paleogeography Symposium 2, p. 133-145.

Brown and Ruth Laboratories, Inc., 1983, The Pacific Northwest 

regional petroleum geochemistry on the onshore and offshore 

sediments of Washington and Oregon Standard Oil of California Kirkpatrick No. 1: Houston, Texas, Brown and Ruth 

Laboratories, Inc., under Oregon Department of Geology and 

Mineral Industries oil and gas contract #1, 6 p.

A12 Mineral Resources of Wilderness Study Areas: John Day Region, Oregon
Buwalda, J.P., 1921, Report on the oil and gas possibilities of 

eastern Oregon: Oregon Bureau of Mines and Geology, The 

mineral resources of Oregon, v. 3, no. 2, 47 p.

Campbell, H.W., and McHugh, E.L., 1987, Mineral resources of 

the Lower John Day and Thirtymile study areas, Gilliam and 

Sherman Counties, Oregon: U.S. Bureau of Mines Open File 

Report MLA-52-87, 17 p.

Centanni, F.A., Ross, A.M., and DeSasa, M.A., 1956, Fluorometric determination of uranium: Analytical Chemistry, v. 28, no. 

11, p. 1651.

Collier, A.J., 1914, The geology and mineral resources of the John 

Day region: Oregon Bureau of Mines and Geology, Mineral 

resources of Oregon, v. 1-3, 47 p.

Committee for the Magnetic Anomaly Map of North America, 

1987, Magnetic anomaly map of North America: Geological 

Society of America, 4 sheets, scale 1:5,000,000.

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.

Davis, Dennis, 1983, Lower John Day GEM resource area: U.S. 

Bureau of Land Management Open-File Report, 13 p.

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

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

Fox, T.P., and Reidel, S.P., 1987, Stratigraphy of the Standard 

Kirkpatrick No. 1, Gilliam County, Oregon: New insight into 

Tertiary tectonism of the Blue Mountains: Oregon Geology, 

v. 49, no. 2, p. 15-22.

Fritts, S.G., and Fisk, L.H., 1985a, Tectonic model for formation 

of the Columbia Basin: Implications for oil, gas potential of 

north central Oregon: Oil and Gas Journal, v. 83, no. 34, p. 

84-88.

 1985b, Structural evolution of south margin relation to 

hydrocarbon generation: Oil and Gas Journal, v. 83, no. 35, 

p. 85-90.

Gottfried, David, Rowe, J.J., and Tilling, R.I., 1972, Distribution 

of gold in igneous rocks: U.S. Geological Survey Professional Paper 727, 42 p.

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

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

Report 84-787, 51 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.

High Life Helicopters, Inc./QEB, Inc., 1981, Airborne gamma-ray 

spectrometer and magnetometer survey, The Dalles quadrangle, Oregon: U.S. Department of Energy Open-File Report 

GJBX-291 (81), v. 2, variously paged.

Jachens, R.C., and Griscom, Andrew, 1985, An isostatic residual 

gravity map of California A residual map for interpretation 

of anomalies from intracrustal sources, in Hinze, W.J., ed., 

The utility of regional gravity and magnetic anomaly maps: 

Tulsa, Oklahoma, Society of Exploration Geophysicists, p. 

347_360.

Jachens, R.C., Simpson, R.W., Blakely, R.J., and Saltus, R.W., 

1985, Isostatic residual map of the United States, exclusive of 

Alaska and Hawaii: National Geophysical Data Center 

(NOAA), Boulder, Colorado, on clear film with interpretive

text, 2 sheets, scale 1:2,500,000.

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.

Lcvinson, A.A., 1974, Introduction to exploration geochemistry: 

Calgary, Canada, Applied Publishing Ltd., p. 43 44.

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 material: Journal of Geochemical Exploration, v. 13, no. 1, p. 77-85.

Merriam, J.C., 1901 a, Geologic section through the John Day 

Basin [abs.]: Geological Society of America Bulletin, v. 12, 

p. 496-497.

Merriam, J.C., 1901b, A contribution to the geology of the John 

Day Basin: University of California Publications in Geological Sciences, v. 2, no. 9, p. 269-314.

Meteorological Committee, Pacific Northwest River Basins 

Commission, 1969, Precipitation, v. 2 of Climatological 

Handbook, Columbia Basin States: Pacific Northwest River 

Basins Commission, 262 p.

Millard, H.T., 1976, Determination of uranium and thorium in 

U.S. Geological Survey standard rocks by the delayed neutron 

technique, in Flanagan, F.J., ed., Descriptions and analyses of 

eight new USGS rock standards: U.S. Geological Survey 

Professional Paper 840, p. 61-66.

Minor, S.A., Ach, J.A., Frisken, J.G., Blakely, R.J., and Campbell, 

H.W., 1988, Mineral Resources of the North Pole Ridge 

Wilderness Study Area, Sherman and Gilliam Counties, Oregon: U.S. Geological Survey Bulletin 1743-B, 18 p.

Morelli, C.E., ed., 1974, The international gravity standardization 

net 1971: International Association of Geodesy Special 

Publication no. 4, 194 p.

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

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

790, 163 p.

Myers, A.T., Haven, R.G., and Dunton, P.J., 1961, A spectrochemical method for the semiquantitative analysis of rocks, 

minerals, and ores: U.S. Geological Survey Bulletin 1084-1, 

p. 207-229.

Nathenson, Manuel, Guffanti, Marianne, Sass, J.H., and Munroe, 

R.J., 1983, Regional heat flow and temperature gradients, in 

Reed, M.J., ed., Assessment of low-temperature geothermal 

resources of the United States 1982: U.S. Geological Survey Circular 892, p. 9-16.

National Geophysical Data Center, 1982, Geothermal resources of 

Oregon: National Oceanic and Atmospheric Administration, 

Boulder, Colo., scale 1:500,000.

Newton, V.C., Jr., 1966, Oil and gas exploration in 1965: The Ore 

Bin, v. 28, no. 1, p. 20-28.

 1968, Oil and gas exploration in Oregon: The Ore Bin, v. 

30, no. 1, p. 12-20.

 1974, Oil and gas exploration in 1973: The Ore Bin, v. 36, 

no. 1, p. 4-8.

 1977, Oil and gas exploration in 1976: The Ore Bin, v. 39, 

no. 1, p. 16-17.

-1979, Petroleum source rock tests on two central Oregon

wells: Oregon Geology, v. 41, no. 4, p. 63-64. 

Reed, M.J., ed., 1983, Assessment of low-temperature geothermal

Mineral Resources of the Lower John Day and Thirtymile Wilderness Study Areas, Oregon A13
resources of the United States 1982: U.S. Geological Survey Circular 892, 73 p

Riccio, J.F., 1978, Preliminary geothermal resource map of Oregon: Oregon Department of Geology and Mineral Industries 

Geological Map Series GM

Riddihough, Robin, Finn, Carol, and Couch, Richard, 1986, Klamath-Blue Mountain lineament, Oregon: Geology, v. 14, no. 

6, p. 528-531.

Robinson, P.T., 1975, Reconnaissance geologic map of the John 

Day Formation in the southwestern part of the Blue Mountains and adjacent areas, north-central Oregon: U.S. Geological Survey Miscellaneous Investigations Series Map 1-872, 

scale 1:125,000.

Scintex Corporation, 1978, UA-3 uranium analyzer: Toronto, 

Scintex Corporation, 45 p.

Strahler, Art, 1969, Physical Geography: New York, John Wiley 

and Sons, Inc., p. 219-238.

Summer, N.S., and Verosub, K.L., 1987, Extraordinary maturation profiles of the Pacific Northwest: Oregon Geology, v. 

49, no. 11, p. 135-140.

Swanson, D.A., 1969, Reconnaissance geologic map of the east 

half of the Bend quadrangle, Crook, Wheeler, Jefferson, 

Wasco, and Deschutes Counties, Oregon: U.S. Geological 

Survey Miscellaneous Geologic Investigations Map 1-568, 

scale 1:250,000.

Swanson, D.A., Anderson, J.L., Camp, V.E., Hooper, P.R., 

Taubeneck, W.H., and Wright, T.L., 1981, Reconnaissance 

geologic map of the Columbia River Basalt Group, northern

Oregon and western Idaho: U.S. Geological Survey OpenFile Report 81-797, 33 p., 5 sheets, scale 1:250,000.

Swanson, D.A., Wright, T.L., Hooper, P.R., and Bentley, R.D., 

1979, Revisions in stratigraphic nomenclature of the Columbia River Basalt Group: U.S. Geological Survey Bulletin 

1457-G, 59 p.

Telford, W.M., Gelhart, L.P., Sheriff, R.E., and Keyes, D.A., 

1976, Applied Geophysics: New York, Cambridge University 

Press, 960 p.

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

Rapid analysis for gold in geologic materials, in Geological 

Research 1968: U.S. Geological Survey Professional Paper 

600-B, p. B130-132.

Thompson, G., Yett, J.R., and Green, K.F., 1984, Subsurface 

stratigraphy of the Ochoco Basin, Oregon: Oregon Department of Geology and Mineral Industries Oil and Gas Investigation OGI-8, 22 p., 7 pi.

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.

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meridian: U.S. Geological Survey Miscellaneous Investigations Series Map 1-902, scale 1:500,000, 2 sheets.

Watkins, N.D., and Batski, A.K., 1974, Magnetostratigraphy and 

oroclinal folding of the Columbia River, Steens, and Owyhee 

basalts in Oregon, Washington, and Idaho: American Journal 

of Science, v. 274, p. 148-189.

A14 Mineral Resources of Wilderness Study Areas: John Day Region, Oregon
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.

L) 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_

LLJ

u

C£

D

O

_

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.

A16 Mineral Resources of Wilderness Study Areas: John Oay Region, Oregon
RESOURCE/RESERVE CLASSIFICATION

ECONOMIC

MARGINALLY 

ECONOMIC

SUBECONOMIC

IDENTIFIED RESOURCES

Demonstrated

Measured

Rese

Indicated

irves

I 

Marginal 

Reserves

Demonstrated 

Subeconomic 

Resources

Inferred

Inferred 

Reserves

Inferred 

Marginal 

Reserves

Inferred 

Subeconomic 

Resources

UNDISCOVERED RESOURCES

Probability Range

Hypothetical Speculative

1

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 John Day and Thirtymile Wilderness Study Areas, Oregon A17
GEOLOGIC TIME CHART

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

EON

 Phanerozoic

Proterozoic

Archean

ERA

Cenozoic

Mesozoic

Paleozoic

Late Proterozoic

Middle Proterozoic

Early Proterozoic

Late Archean

Middle Archean

Early Archean

PERIOD

Quaternary

Tertiary

Neogene 

Subperiod

Paleogene 

Subperiod

Cretaceous

Jurassic

Triassic

Permian

Carboniferous 

Periods

Pennsylvanian

Mississippian

Devonian

Silurian

Ordovician

Cambrian

t?annj\

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

pre-Archean2

ACE ESTIMATES OF 

BOUNDARIES IN 

MILLION YEARS (Ma)

 0.010

1.7

5

24

"3Q

 55

 66

96 

1 an

 205

^-240

 290 

_,a an

 360

 410 

 435

 500

j/ \j

 1600

£*+)\J\J

3 \AJ\J

 3400

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

informal time term without specific rank.

A18 Mineral Resources of Wilderness Study Areas: John Day Region, Oregon
SELECTED SERIES OF U.S. GEOLOGICAL SURVEY PUBLICATIONS

Periodicals

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

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