Mineral Resources of the 

North Stansbury Mountains 

Wilderness Study Area, 

Tooele County, Utah

U.S. GEOLOGICAL SURVEY BULLETIN 1745-B

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Chapter B

Mineral Resources of the 

North Stansbury Mountains 

Wilderness Study Area, 

Tooele County, Utah

By MICHAEL P. FOOSE and KAREN A. DUTTWEILER 

U.S. Geological Survey

CARL L ALMQUIST 

U.S. Bureau of Mines

U.S. GEOLOGICAL SURVEY BULLETIN 1745

MINERAL RESOURCES OF WILDERNESS STUDY AREAS NORTHWESTERN UTAH
DEPARTMENT OF THE INTERIOR 

MANUEL LUJAN, JR., Secretary

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director

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For sale by the

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Library of Congress Cataloging-in-Publication Data

Mineral resources of the North Stansbury Mountains Wilderness Study Area, 

Tooele County, Utah / by Michael P. Foose, Karen A. Duttweiler, and Carl L 

Almquist.

p. cm. (Mineral resources of wilderness study areas Northwestern Utah ; ch. B) (U.S. Geological Survey bulletin ; 1745-B)

Bibliography: p.

Supt. of Docs, no.: I 19.3:1745-B

1. Mines and mineral resources Utah North Stansbury Mountains 

Wilderness. 2. North Stansbury Mountains Wilderness (Utah) I. Duttweiler, 

K. A. II. Almquist, Carl L III. Title. IV. Series. V. Series: Studies related 

to wilderness. VI. Series: U.S. Geological Survey bulletin ; 1745-B. 

QE75.B9 no. 1745-B 

[TN24.U8]

557.3 s-dc19 89-600008 

[553'.09792'43] CIP
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 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 North Stansbury Mountains 

(UT-02CW)89) Wilderness Study Area, Tooele County, Utah.

CONTENTS

Abstract Bl 

Summary Bl

Character and setting Bl 

Identified mineral resources B3 

Mineral resource potential B3 

Introduction B5

Location and setting B5 

Investigations by the U.S. Bureau of Mines B5 

Investigations by the U.S. Geological Survey B5 

Geologic setting B7 

Acknowledgments B8 

Appraisal of identified resources B8 

Mining activity B8 

Sites examined for this study B8 

Conclusions B9

Assessment of mineral resource potential BIO 

Geology BIO 

Geochemistry BIO 

Methods BIO

Results and interpretation Bll 

Geophysics B12

Aerial radiometric survey B12 

Aeromagnetic survey B12 

Regional gravity survey B12 

Mineral and energy resources B12

Lead, zinc, silver, gold, and mercury in vein and replacement

deposits B12

Gold in sediment-hosted, disseminated deposits B13 

Geothermal resources B13 

Oil and gas B13 

References cited B14 

Appendix B15

FIGURES

1-4. Maps of the North Stansbury Mountains Wilderness Study Area and vicinity:

1. Location B2

2. Mineral resource potential and pertinent geologic features B4

3. Geochemical sampling localities, mines, prospects, mining claims, and 

areas represented by samples having anomalous metal concentrations B6

4. Lands under lease for oil and gas B9

Contents

MINERAL RESOURCES OF WILDERNESS STUDY AREAS-NORTHWESTERN UTAH

Mineral Resources of the 

North Stansbury Mountains 

Wilderness Study Area, 

Tooele County, Utah

By Michael P. Foose and Karen A. Duttweiler 

U.S. Geological Survey

Carl L Almquist 

U.S. Bureau of Mines

ABSTRACT

In 1985, the U.S. Bureau of Mines and the U.S. 

Geological Survey appraised the mineral resources and 

assessed the mineral resource potential of the North Stansbury Mountains (UT-020-089) Wilderness Study Area. This 

area covers approximately 10,175 acres (15.9 square miles) 

near the northern end of the Stansbury Mountains in 

northwestern Utah. The area lies 45 miles west of Salt Lake 

City, about 20 miles west of the Oquirrh Mountains, and 55 

miles northwest of the East Tintic Mountains. Both the 

Oquirrh and East Tintic Mountains are noted for large baseand precious-metal deposits.

A small area in the southeastemmost part of the study 

area has inferred subeconomic resources of limestone 

suitable for use in making cement. Inferred subeconomic 

resources of sand and gravel exist within Muskrat Canyon. 

These inferred subeconomic resources are not likely to be 

developed. There are no other identified resources in the 

study area.

Mineral occurrences and geochemical anomalies in 

and near the study area are similar to those observed near 

some of the deposits in the Oquirrh and East Tintic 

Mountains and provide evidence that hydrothermal 

mineralization has occurred within the eastern and southern 

parts of the study area. These parts are considered to have a 

moderate mineral resource potential for undiscovered lead, 

zinc, silver, gold, and mercury in vein and replacement

Manuscript approved for publication February 1,1989.

deposits. The remaining parts of the study area are assigned 

a low mineral resource potential for lead, zinc, silver, gold, 

and mercury in vein and replacement deposits.

In the southwestern and eastern parts of the study area, 

some samples contain anomalous amounts of silver, 

bismuth, antimony, arsenic, and, in a few cases, mercury. 

This same geochemical suite is associated with some 

sediment-hosted disseminated gold deposits, such as the 

Mercur deposit in the adjacent Oquirrh Mountains. Based on 

this association, areas underlain by carbonate and finegrained siliceous rocks in the southern and eastern parts of 

the study area are assigned a moderate potential for 

undiscovered sediment-hosted, disseminated gold 

resources. The remainder of the area has low potential for 

gold resources.

A small portion of the southwestern part of the study 

area may contain thermal waters and is assigned a moderate 

potential for undiscovered geothermal resources. The entire 

study area is assigned a low potential for oil and gas 

resources.

SUMMARY

Character and Setting

The North Stansbury Mountains Wilderness Study Area 

comprises approximately 10,175 acres (15.9 square miles) 

located 45 mi (miles) west of Salt Lake City, Utah (fig. 1). The 

area is near the northern end of the Stansbury Mountains and 

is bounded to the west by Skull Valley and to the east by 

Tooele Valley. Elevations in these flanking valleys are 

between 4,200 and 4,300 ft (feet), and the maximum

North Stansbury Mountains Wilderness Study Area B1
Lakeside 

Mountains

BOUNDARY OF 

STANSBURY MOUNTAINS 

WILDERNESS STUDY AREA 

(UT-020-089

Skull Valley

Tooele valley

Figure 1 . Location of the North Stansbury Mountains Wilderness Study Area, Tooele County, Utah. Letters show locations 

of the Bingham (B), Stockton (S), Ophir (6), and Mercur (M) mining districts in the Oquirrh Mountains.

B2 Mineral Resources off Wilderness Study Areas Northwestern Utah
elevation within the study area is 8,885 ft. Access to the area 

is provided by several unpaved roads and by Interstate 

Highway 80, which passes within 3 mi of the northern end of 

the area.

The Stansbury Mountains, including the study area, lie 

within the eastern Great Basin, an area that is also part of the 

Basin and Range structural province. The following 

generalized geologic history of this area is taken from Tooker 

(1983).

Carbonate and clastic sediments were deposited as 

part of a westward-thickening miogeocline during the early 

Paleozoic (Cambrian through Devonian). (See geologic age 

chart in the Appendix.) This deposition was interrupted in the 

Devonian by uplift on the east-west-trending Cortez-Uinta 

axis. Unconformable clastic sediments deposited during this 

uplift grade upward into a sequence of Mississippian through 

Permian sediments, most of which were deposited in shallow 

water. During the Mesozoic, eastward-directed thrusting 

resulting from the Sevier orogeny developed a series of 

imbricated thrust sheets. Mesozoic sediments are preserved 

in only a few of these. Thrusting was followed by some 

Tertiary igneous activity, which emplaced several small 

intrusions of intermediate composition in the central part of 

the range (Davis, 1959). Cenozoic normal faulting and 

eastward tilting have subsequently segmented these rocks to 

form north-trending mountain ranges that are flanked by 

intervening valleys filled with young clastic sediments.

The young sediments filling Tooele Valley separate the 

study area from the Oquirrh Mountains, which lie 

approximately 20 mi to the east (fig. 1). These adjacent 

mountains host the copper, lead, zinc, silver, and gold 

mineralization of the extremely large Bingham mining district 

and the smaller Stockton and Ophir districts to the south. Still 

farther south is the Mercur disseminated gold deposit 

(Kornze, 1987). In the East Tintic Mountains, 25 mi farther 

south, are the silver, lead, gold, copper, and zinc vein and 

replacement deposits of the East Tintic district.

Identified Mineral Resources

The Free Coinage mining district, whose boundaries 

are not well defined, probably includes the study area, but 

there are no mines or active mining claims within the study 

area. Lead and zinc have been mined at several localities 

within 1 mi east of the study area, and the workings of one 

mine extend to its eastern boundary. Mercury reportedly was 

mined from limestone breccias 1 mi east of the study area. 

Limestone that crops out in a small area in the southeasternmost part of the study area is quarried for use as cement raw 

material 2 mi to the east. The limestone is classified as an 

inferred subeconomic resource. Sand and gravel, present 

mainly in Muskrat Canyon, is poorly sorted and made up of 

material ranging from sand-size particles to boulders. The 

sand and gravel is classified as an inferred subeconomic 

resource because it is far from market and not likely to be 

developed. No other identified resources are present.

Mineral Resource Potential

Geological and geochemical evidence indicates that 

some of the eastern and southern parts of the study area

have been mineralized by hydrothermal solutions. This 

mineral enrichment is most clearly evident at several mines 

and prospects, most of which are located outside but close to 

the eastern margin of the study area. However, a few 

prospects are within the study area, and geochemical 

anomalies similar to those associated with these mines and 

prospects are also found in the study area. These 

occurrences indicate that mineralization, similar to that which 

has enriched parts of the Oquirrh and East Tintic Mountains, 

has affected this part of the Stansbury Mountains.

The mines, prospects, and geochemical anomalies 

along the eastern part of the study area closely follow the 

contact that separates Lower Devonian and older rocks from 

Upper Devonian and younger rocks. This association 

suggests that this contact, which is probably an unconformity, localized hydrothermal solutions. However, some similar 

mineral occurrences in the south-central part of the study 

area are not near this contact and indicate that shears and 

fractures also were conduits for mineralizing solutions. 

Therefore, not all mineralization in the study area was 

confined to areas that are near the contact between older and 

younger Devonian rocks.

The geochemical signature of mineral occurrences in 

and near the study area is similar to that of some of the lead, 

zinc, silver, gold, and mercury replacement deposits found in 

peripheral parts of the Bingham mining district (Rubrightand 

Hart, 1968) and in the vein and replacement deposits of the 

East Tintic district (Morris and Levering, 1979). The data 

indicate that similar mineralization has occurred within the 

eastern and southern parts of the study area, and these areas 

are therefore assigned a moderate potential for undiscovered 

lead, zinc, silver, gold, and mercury resources in vein and 

replacement deposits (fig. 2).

The remaining part of the study area is underlain by 

carbonates and shales, which may be favorable host rocks 

for replacement and vein deposits. Fractures and faults in 

this area may be mineralized, although we have found no 

specific evidence that they are. This area is, therefore, 

assigned a low mineral resource potential for metals in 

replacement and vein deposits.

Some of the samples from the south-central and 

eastern parts of the study area have anomalous 

concentrations of gold, silver, arsenic, antimony, and 

bismuth. High concentrations of mercury are also observed 

in some of these samples. This geochemical suite is 

characteristic of sediment-hosted disseminated gold 

deposits, such as the Mercur deposit in the southern part of 

the adjacent Oquirrh Mountains. On the basis of this 

geochemical association, a moderate potential for 

undiscovered gold resources in sediment-hosted 

disseminated deposits is assigned to the southern and 

eastern parts of the study area, except where the bedrock is 

quartzite (fig. 2).

Warm springs occur in both Skull and Tooele Valleys at 

the north end of the Stansbury Mountains. The southwest 

part of the study area extends into Skull Valley, and the 

potential for undiscovered geothermal resources in this area 

is rated as moderate.

North Stansbury Mountains Wilderness Study Area B3
112°40' TIMPIE2.5MI 37'30" 112°35'

^^-APPROXIMATE BOUNDARY OF 

' NORTH STANSBURY MOUNTAINS 

WILDERNESS STUDY AREA 

(UT-020-089)

'

Upper Devonian :\vi--^V/.V-N, and youn-°- ' ' ' - ' '"

2 MILES

J

R 7 W R 6 W

Figure 2 (above and facing page). Mineral resource potential and pertinent geologic features of the North 

Stansbury Mountains Wilderness Study Area, Tooele County, Utah.

B4 Mineral Resources of Wilderness Study Areas Northwestern Utah
EXPLANATION OF MINERAL 

RESOURCE POTENTIAL

Area having inferred subeconomic resource of sand and gravel

Area having inferred subeconomic resource of limestone 

suitable for use in cement Resource is in the Mississippian Great Blue Limestone, which crops out only in the 

southeast corner of the study area

Geologic terrane having moderate mineral resource potential for vein and replacement deposits of lead, zinc, 

silver, gold, and mercury, with certainty level C 

Applies to all areas shown in pink, with and without 

stripes

Geologic terrane having moderate mineral resource potential for sediment-hosted disseminated gold resources, 

with certainty level B Applies to all areas marked "M/B"

Geologic terrane having moderate resource potential for 

geothermal energy, with certainty level B

Geologic terrane having low mineral resource potential for 

oil and gas and (or all metals, with certainty level B For

oil and gas, applies to entire study area; for metals, applies 

only outside the "moderate" (pink) areas

Levels of certainty:

Data indicate geologic environment and suggest the level 

of resource potential

Data indicate geologic environment and give a good 

indication of the level of resource potential

GEOLOGIC FEATURES 

Alluvial deposits of Quaternary age

 Contact separating Lower Devonian and older rocks from 

Upper Devonian and younger rocks

===== Paved road 

========= Unpaved road

The energy resource potential for oil and gas in the 

entire study area is considered to be low. Although most 

current thinking suggests that the rock types and the thermal 

history of this area make oil and gas accumulations unlikely, 

it is also recognized that some current assumptions could be 

disproven by further work. Particularly, it is possible that 

some hydrocarbons may have accumulated in some of the 

younger rocks along the west edge of the study area.

INTRODUCTION

Location and Setting

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

Management (BLM), approximately 10,175 acres (15.9 

square miles) that constitute the North Stansbury 

Mountains Wilderness Study Area were studied to 

appraise the mineral resources and assess the mineral 

resource potential. This area, which is referred to in this 

report as the study area, is in the northern part of the 

Stansbury Mountains (fig. 1), about 45 mi (miles) west of 

Salt Lake City, Utah. It is bounded on the west by Skull

Valley and on the east by Tooele Valley. Elevations in 

these flanking valleys are between 4,200 and 4,300 ft 

(feet), and the maximum elevation within the study area 

is 8,885 ft. Several unpaved roads extend to the flanks of 

the area and provide access to it. A major route, 

Interstate Highway 80, passes 3 mi north of the study 

area boundary.

This report presents an evaluation of the mineral 

endowment (identified resources and mineral resource 

potential) of the study area and is the product of several 

separate studies by the U.S. Bureau of Mines (USBM) 

and the U.S. Geological Survey (USGS). Identified 

resources are classified according to the system of the 

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

(1980), which is shown in the Appendix of this report. 

Identified resources are studied by the USBM. Mineral 

resource potential is the likelihood of occurrence of 

undiscovered metals and nonmetals, industrial rocks and 

minerals, and of undiscovered energy sources (coal, oil, 

gas, oil shale, and geothermal sources). It is classified 

according to the system of Goudarzi (1984), which also is 

shown in the Appendix. Undiscovered resources are 

studied by the USGS.

Investigations by the 

U.S. Bureau of Mines

Investigations by the USBM included a review of 

published literature, unpublished USBM and BLM file 

data, and mining claim and land status records; a field 

investigation of mines, prospects, and mineralized areas; 

and an evaluation of analyses of 107 chip, grab, and select 

samples and 5 panned-concentrate samples (fig. 3). 

Samples from the area were analyzed by Bondar-Clegg, 

Inc., Lakewood, Colo. Gold was determined by fire assay 

plus atomic absorption; lead, zinc, copper, silver, and 

beryllium by atomic absorption; and mercury by coldvapor atomic absorption. Limestone samples were 

analyzed by whole-rock methods. Complete analytical 

results are available for public inspection at the U.S. 

Bureau of Mines, Intermountain Field Operations 

Center, Building 20, Denver Federal Center, Denver, 

Colo.

Investigations by the 

U.S. Geological Survey

Rigby (1958) presented a detailed discussion of the 

geology of the Stansbury Mountains, including stratigraphy and structure. Subsequently, Rigby's stratigraphic 

work has been slightly modified and generalized by 

Sorensen (1982) for a mineral resource appraisal of the 

area immediately to the south of the study area. In order

North Stansbury Mountains Wilderness Study Area B5
112°40' TIMPIE2.5MI 37'30" 112°35'

'.^APPROXIMATE BOUNDARY OF 

t NORTH STANSBURY MOUNTAINS 

WILDERNESS STUDY AREA 

(UT-020-089)

Reader mining claim group

11 Monte Carlo Mine

Utah Bunker Hill Mine

Lead Queen mining 

claim group

 Upper Devonian

and younger 

Lower Devonian 

and older

2 MILES

R 7 W R 6 W

Figure 3 (above and facing page). Geochemical sampling localities, mines, prospects, mining claims, and 

areas represented by samples having anomalous metal concentrations in and near the North Stansbury 

Mountains Wilderness Study Area, Utah.

B6 Mineral Resources of Wilderness Study Areas Northwestern Utah
-K

B

EXPLANATION

U.S. Geological Survey sampling localities:

Panned concentrate and rock sample

Panned concentrate only

Rock sample only 

U.S. Bureau of Mines sampling localities:

Panned concentrate

Rock sample 

Locality discussed in text

Drainage areas represented by samples having anomalous 

metal concentrations

Unpatented mining claims

Prospect pit

Adit

Inaccessible adit

Shaft

Contact separating Lower Devonian and older rocks from 

Upper Devonian and younger rocks

Paved road

= = = ===== Unpaved road

to provide continuity with Sorensen's work, his more 

generalized stratigraphy was used in this study. The 

USGS authors did additional field mapping in the area 

and compared their results with those of Rigby (1958). 

Where appropriate, Rigby's work was modified (Foose, 

in press). In addition, regional geochemical sampling and 

site-specific sampling, as described below, were 

conducted.

Geologic Setting

The Stansbury Mountains, including the study 

area, are within the Basin and Range structural province. 

Tooker (1983) has summarized the geology of this 

region. According to Tooker, Cambrian through Devonian carbonate and clastic sediments were deposited as 

part of a westward-thickening miogeocline. Late Devonian uplift interrupted this sedimentation and created an 

erosional unconformity. Upper Devonian clastic 

sediments deposited on this unconformity grade upward 

into a sequence of mostly shallow-water Mississippian 

through Permian sediments. Eastward-directed thrusting, 

resulting from the Mesozoic Sevier orogeny, deformed 

these rocks and created a series of imbricated thrust 

sheets. Mesozoic sediments occur in only a few of these 

sheets. Subsequent Tertiary igneous activity is 

represented by several small intrusions of intermediate 

composition that occur mostly in the central portion of

the Stansbury Mountains (Davis, 1959). Finally, Cenozoic normal faulting has segmented these rocks to form 

north-trending mountain ranges that are characteristic of 

the Basin and Range province. The intervening valleys 

have been filled with young clastic sediments, largely 

derived from the adjacent mountains.

The young sediments filling Tooele Valley separate 

the study area from the mineral-rich Oquirrh Mountains, 

which lie approximately 20 mi to the east. These adjacent 

mountains contain the large Bingham mining district (fig. 

1), which includes one of the world's largest porphyry 

copper deposits. Bingham has produced more copper 

than any other mine in the world and leads the state of 

Utah in gold production. Hydrothermal vein and 

replacement deposits within this district show a 

concentric zoning, from deposits rich in molybdenum and 

copper outward to deposits having predominantly lead, 

zinc, and silver (John, 1975). Some of these lead-zinc 

replacement deposits are also rich in mercury (Rubright 

and Hart, 1968). Other mineralized areas in the Oquirrh 

Mountains occur south of the Bingham district. These 

include the lead, silver, copper, zinc, and gold deposits in 

the Stockton and Ophir districts, and the disseminated 

gold and mercury of the Mercur deposit (fig. 1). 

Approximately 25 mi south of the Mercur deposit, in the 

East Tintic Mountains, are the vein and replacement 

deposits of the East Tintic mining district. These deposits 

range from copper-, gold-, silver-, lead-, and zinc-bearing 

fissures and veins, which occur mostly in the Cambrian 

Tintic Quartzite, to large lead and zinc replacement 

deposits that are concentrated in middle Cambrian 

carbonates. Tertiary felsic intrusions adjoin the ore zones 

in all of these districts (Morris and Levering, 1979; 

Moore and McKee, 1983), although a direct genetic 

relationship is not certain in all cases.

Felsic intrusive rocks of the type associated with 

ore deposits in the Oquirrh and East Tintic Mountains 

are not exposed in the study area. However, a small 

monzonite porphyry occurs within a half mile of the 

southeast corner of the study area, and several other 

small felsic intrusions occur south of the study area 

(Rigby, 1958; Davis, 1959).

The general lack of felsic intrusive rocks in the 

northern part of the Stansbury Mountains may, in part, 

be due to its location north of the Cortez-Uinta structural 

axis. This roughly east-west-trending arch appears to be 

an important and long-lived structural feature in this 

region (Tooker, 1983). Movement along this axis, which 

passes just south of the Bingham district and trends 

through - South Mountain (fig. 1), disrupted 

sedimentation in the Devonian and then, much later, 

apparently acted to localize intrusions and associated 

mineralization in the Tertiary. For example, the Park 

City, Alta-Cottonwood, and Bingham districts form an 

east-west trend coincident with this axis (Smith, 1975).

North Stansbury Mountains Wilderness Study Area B7
Tooker and Roberts (1971) suggest that this feature 

provided a structurally favorable zone of weakness along 

which magmas could intrude and localize mineral 

deposits.

Within the Stansbury Mountains, however, areas 

south of the study area, which lie on the Cortez-Uinta 

axis, also contain fewer felsic intrusive rocks than do the 

adjacent Oquirrh Mountains (Moore and Sorensen, 

1979; Moore and McKee, 1983). Tooker and Roberts 

(1971) suggest that the Oquirrh and Stansbury 

Mountains are part of a westward-thickening sequence of 

stacked thrust sheets. Tooker (oral commun., 1987) 

speculates that the stack of thrust slices in the Stansbury 

Mountains, being thicker than in the Oquirrh Mountains, 

either inhibited emplacement of magmas or induced 

them to solidify at greater depths so that they have not 

been exposed. Regardless of the relative paucity of 

igneous rocks near the study area, it is apparent that the 

base- and precious-metal-rich veins and concentrations 

of mercury found along the eastern margin of the study 

area indicate that this part of the Stansbury Mountains 

has been affected by mineralization similar to that which 

has enriched the Oquirrh and East Tintic Mountains.

Acknowledgments

U.S. Geological Survey field work was done with 

the assistance of William Moore, Ricardo Lopez, and 

Jerry Gaccetta. U.S. Bureau of Mines personnel assisting 

in the field work were Patricia A. Corbetta and Russell 

A. Schreiner.

APPRAISAL OF IDENTIFIED RESOURCES

By Carl L. Almquist 

U.S. Bureau of Mines

Mining Activity

The Free Coinage mining district, organized in 

1895, apparently included the entire study area, but its 

boundaries are uncertain (Butler and others, 1920, p. 

147,149). Mining activity centered on lead-zinc deposits 

in Mississippian rocks along the east side of the Stansbury Mountains. Most of the district's production came 

from two mines: the Monte Carlo Mine, on the eastern 

boundary of the study area, and the Utah Bunker Hill 

Mine, one-half mile farther east (fig. 3). Recorded 

production from the district, from 1917 through 1948, 

totaled 449,244 pounds of lead, 5,400 pounds of zinc, 

1,458 pounds of copper, 6,160 ounces of silver, and 5.17

ounces of gold from 1,053 tons of ore (U.S. Geological 

Survey, 1917-1923; U.S. Bureau of Mines, 1924-1948). 

Nearly 2,000 ft of underground workings were driven at 

the Lead Queen Mine in an unsuccessful effort to 

intersect the subsurface extension of a lead-zinc vein 

outcrop (Oliver Peasnall, Lead Queen Mine owner, oral 

commun., 1986). In the 1950's, mercury reportedly was 

produced from a deposit near the head of Timpie Valley 

(location E, fig. 3) and sold on the local market (Rigby, 

1958, p. 125). As of January 1987, there were no mining 

claims in the study area.

At the time of the USBM's investigation, Genstar 

Cement and Lime Co., Grantsville, Utah, and Lonestar 

Industries Inc., Salt Lake City, Utah, were quarrying 

limestone and dolomite in the vicinity of processing 

facilities at Flux and Dolomite, 2-3 mi east of the study 

area (fig. 1). One of the quarried formations, the Mississippian Great Blue Limestone, crops out in the extreme 

southeast part of the study area (Rigby, 1958).

Sites Examined for This Study

Metallic mineral occurrences at the north end of 

the Stansbury Mountains are confined to moderately 

deformed, steeply dipping Mississippian limestones and 

dolomites. Faults and fissures along the contact between 

these rocks and Lower Devonian and older rocks were 

conduits for mineralizing solutions that deposited lead, 

zinc, copper, silver, mercury, and gold.

The most abundant mineral commodity in the area 

is lead. It occurs along with zinc, copper, silver, and 

traces of gold in irregular-shaped replacement deposits 

in some of the prospects and mines shown in figure 3. 

The ore consists of argentiferous galena, quartz, calcite, 

limonite, occasional pyrite and chalcopyrite, and lead and 

zinc carbonate alteration minerals. Host rocks are jasperized or silicified and commonly contain barren quartz 

and calcite stringers. Samples of lead-zinc vein material 

contained as much as 11.80 percent lead, 11.70 percent 

zinc, 0.36 percent copper, 2.99 ounces of silver per short 

ton, and 30 parts per billion gold (Almquist, 1987, table

2).

At the Monte Carlo Mine, which extends to the 

eastern boundary of the study area, underground 

workings consist of three adits driven at different levels to 

intersect a fissure-vein lead-zinc deposit exposed at the 

head of Miners Canyon. At the lowest accessible point in 

underground workings (Almquist, 1987, fig. 3), the vein 

strikes north and dips 65 degrees west. This underground 

point is close to the study area boundary and may be 

within it. Judging from the size and shape of the stope at 

this depth, the vein was an irregular podlike mass about 

5-6 ft thick and 40-60 ft wide. Sloping extended above 

the haulage level, probably to the upper adit driven on 

the vein's surface exposure, and for an undetermined

B8 Mineral Resources of Wilderness Study Areas Northwestern Utah
distance below. The vein, which reportedly contained 

35-40 percent lead (Buranek, 1942, p. 4), was probably 

mined out between the upper and lower adits, a vertical 

distance of nearly 280 ft. Samples from the walls of the 

stope on the Monte Carlo vein contained as much as 1.41 

ounces of silver per short ton, 8.10 percent lead, and 2.19 

percent zinc (Almquist, 1987, fig. 3).

Near the head of Timpie Valley, mercury and low 

concentrations of gold were deposited in limestone breccia. The breccia is in a shear zone that strikes northerly 

and dips steeply east. Cinnabar is disseminated in quartz 

and calcite gangue. A select sample of mineralized 

limestone breccia contained more than 1,000 parts per 

million mercury and 75 parts per billion gold (Almquist, 

1987, table 2).

In the early 1960's, the U.S. Bureau of Mines 

(unpublished data, 1961-1963) investigated reported 

occurrences of nonpegmatitic beryllium at several sites in 

the northern Stansbury Mountains, but none were found. 

Twelve samples collected during the present 

investigation were analyzed for beryllium but no 

significant concentrations were detected (Almquist, 

1987, fig. 3 and table 2).

No mineralized areas were identified in the part of 

the study area west of the range crest. Gold was detected 

in a panned-concentrate sample collected by the USGS 

on the west side of the study area (see geochemistry 

results section later in this report), but none was detected 

in the five panned-concentrate samples collected by the 

USBM in the study area.

The only nonmetallic mineral commodity of 

interest is an outcrop of the Mississippian Great Blue 

Limestone, classified as an inferred subeconomic 

resource, in the extreme southeast corner of the study 

area. Limestone from this site is similar in quality to 

limestone from a nearby active quarry in the same 

formation (Almquist, 1987, plate 1, sample localities 101 

and 112, respectively; table 1). Limestone from the 

quarry is used by Lone Star Industries, Inc., to produce 

raw material for cement (Bryce Tripp, staff geologist, 

Utah Geological and Mineral Survey, written commun., 

1986). Limited outcrop at the exposure within the study 

area prevented measurements necessary for calculating 

deposit size, but according to Rigby's geologic map 

(1958, plate 1), the Great Blue Limestone underlies 

approximately 20 acres in the southeast corner of the 

study area.

Alluvial deposits in the study area, classified as 

inferred subeconomic resources, consist of poorly sorted 

material ranging in size from sand to boulders. These 

deposits, which occur in Muskrat Canyon and other 

canyons extending into the study area on the west side,

represent a small fraction of the abundant supply of sand 

and gravel available in established pits and other more 

accessible sites along the flanks of the Stansbury 

Mountains.

As of August 1985, 4,400 acres of the study area 

were under lease for oil and gas (fig. 4), though no wells 

have been drilled in the study area and no producing 

fields are near the area.

Conclusions

Inferred subeconomic resources of limestone and 

sand and gravel are in the study area. The Mississippian 

Great Blue Limestone is exposed in the extreme 

southeast corner of the study area. Limestone at this

112° 40' 37'30" 112° 35'

40° 

40'

40° 

37' 

30'

APPROXIMATE BOUNDARY OF 

NORTH STANSBURY MOUNTAINS 

/WILDERNESS STUDY AREA (UT-020-089)

2 MILES

J

Figure 4. Lands under lease for oil and gas (shaded) in the 

North Stansbury Mountains Wilderness Study Area, Utah 

(Almquist, 1987).

North Stansbury Mountains Wilderness Study Area B9
locality is similar in quality to limestone being quarried 2 

mi to the east, but it would not be utilized in favor of 

more accessible sources that are closer to processing 

facilities. Sand and gravel in Muskrat Valley and in other 

drainages are poorly sorted, have no unique qualities, 

and are not likely to be utilized.

Mississippian carbonate rocks in the north end of 

the Stansbury Mountains, less than 1 mi from the study 

area, host occurrences of lead, zinc, copper, silver, 

mercury, and low concentrations of gold. These Mississippian host rocks are exposed along the eastern 

boundary of the study area.

ASSESSMENT OF MINERAL RESOURCE 

POTENTIAL

By Michael P. Foose and 

Karen A. Duttweiler 

U.S. Geological Survey

Geology

Rocks within the study area may be divided into 

three groups. The first of these is Cambrian through 

Lower Devonian in age and consists of (1) a thick 

Cambrian quartzite (Tintic Quartzite), the base of which 

is not exposed, (2) overlying shales and sandstones 

(Ophir Group rocks), and (3) interlayered Cambrian 

through Lower Devonian limestones, shales, and 

dolomites. The thickness of this lower Paleozoic 

sequence is about 10,000 ft (Rigby, 1958; Tooker and 

Roberts, 1971; Sorensen, 1982). A major break, which 

may be either an unconformity or a thrust fault, separates 

these lower rocks from the second group, which consists 

locally of Upper Devonian conglomerate (Stansbury 

Formation) and overlying limestones and calcareous 

sandstones of Upper Devonian and Mississippian age. 

The third group of rocks is made up of younger surficial 

deposits and a few exposures of Tertiary basalt flows that 

locally cover parts of the area.

These rocks have been folded into two northeasttrending anticlines and an intervening syncline. The folds 

have an average trend of N. 11° E. and a plunge of 20° 

NE. Axial planar cleavages are locally well developed in 

the centers of folds, but otherwise are generally absent or 

weakly developed. Subsequent to folding, these rocks 

have been slightly disrupted by basin-and-range faulting.

The nature of the contact between the first 

sequence (Lower Devonian and older rocks) and the 

second sequence (Upper Devonian and younger rocks) is 

not clear. Rigby (1958) interprets this contact to be an 

unconformity, an interpretation that is consistent with

this region's general geologic history. However, Tooker 

and Roberts (1971) suggest that this particular contact is 

a west-dipping thrust. Exposures in the study area were 

not sufficient to determine which of these interpretations 

is correct. However, several lines of evidence support 

Rigby's interpretation. First, the Stansbury Formation, 

which locally is immediately above this contact, varies 

widely in thickness and locally contains abundant and 

large clasts derived from underlying rocks. It therefore 

indicates a major erosional period. Second, observations 

made by W J. Moore and M.L. Sorensen outside and to 

the north of the study area indicate that this contact is 

paraconformable and dips east. They found no evidence 

of a west-dipping thrust (Moore, written commun., 1985; 

Sorensen, oral commun., 1987). Third, the thrust 

hypothesis requires younger rocks to have been 

emplaced over older rocks along a thrust that cuts 

through a considerable stratigraphic thickness of lower 

plate rocks without regard to differences in lithology and 

at right angles to their strike (Rigby, 1958; Foose, in 

press). Such stratigraphic and crosscutting relations are 

not typical of thrust systems.

Although this contact is probably not a westdipping thrust, rocks near it do show evidence of 

shearing. Specifically, rocks adjacent to it are commonly 

brecciated, veined, and silicified. These features may 

have developed as a result of differential movement 

along the angular unconformity during folding and 

subsequent introduction of hydrothermal fluids.

This contact between the older and younger 

sequences of rocks clearly exerted an important control 

in localizing mineralization. The Utah Bunker Hill and 

Monte Carlo Mines and the mercury deposit near the 

head of Timpie Valley (location E, fig. 3) are all situated 

near this contact. Anomalous metal values have been 

determined from rocks, stream-sediments, and panned 

concentrates collected elsewhere along or near this 

contact. The distribution of mineralized areas along this 

contact indicates a laterally extensive zone along which 

hydrothermal solutions moved.

Geochemistry

Methods

During the summer of 1986, the USGS conducted 

a reconnaissance geochemical survey of the North Stansbury Mountains Wilderness Study Area. Minus-30-mesh 

(<0.6-mm) stream-sediment samples, nonmagnetic 

heavy-mineral concentrates derived from the streamsediment samples, and rock samples were collected. 

Stream sediments were useful because they represent a 

composite of rock and soil exposed in the drainage basin 

upstream from the sample site; since minus-30-mesh 

sediments are coarse, they contain relatively little of the

BIO Mineral Resources of Wilderness Study Areas Northwestern Utah
very fine grained wind-borne material, which commonly 

contaminates stream-sediment samples in arid regions, 

such as the study area. The nonmagnetic fraction of 

heavy-mineral concentrates is useful in locating 

mineralized areas because it may contain ore and orerelated minerals, and the selective concentration of these 

heavy minerals permits determination of some elements 

that are not easily detected in bulk stream-sediment 

samples.

Altogether, 21 stream-sediment and concentrate 

samples and 69 rock samples were collected (fig. 3). 

Rock samples were taken from loose pieces along stream 

courses, from outcrops, and from prospects and mines. 

Analytical data, sample localities, and descriptions of the 

sampling and analytical techniques are given in Adrian 

and others (1989) and Foose (in press).

Results and Interpretation

Three areas having anomalous metal concentrations (areas 1,2, and 3 in fig. 3) were delineated by 

data from stream sediments and nonmagnetic heavymineral concentrates. Area 1 straddles the southeast 

border of the study area west of Miners Canyon; area 2 

consists of two drainages near the head of Timpie Valley 

that extend into the northeast part of the study area; and 

area 3 includes much of the south-central part of the 

study area.

Area 1 includes the Utah Bunker Hill Mine and is 

near the Monte Carlo Mine. Stream-sediment samples 

were collected both downstream and upstream of the 

Utah Bunker Hill Mine (locations A and B respectively, 

fig. 3) and from a small tributary which joins Miners 

Canyon downstream from the mine (location C). These 

minus-30-mesh stream-sediment samples contain high 

concentrations of zinc (100 parts per million, or ppm), 

cadmium (1.5-1.6 ppm), and arsenic (23-27 ppm). The 

nonmagnetic heavy-mineral-concentrate samples contain 

trace amounts of galena and corresponding anomalous 

concentrations of lead (500-3,000 ppm) and also have 

high amounts of zinc (700 ppm) and barium (2,000 ppm).

Mineralized and altered rock samples from the 

mines and nearby areas have anomalous values ranging 

up to 16,000 ppm for zinc, 50 ppm for cadmium, more 

than 20,000 ppm for lead, and 150 ppm for silver. Some 

rocks also show high concentrations of copper, bismuth, 

arsenic, and antimony. Outside of this area, along strike 

with the Lower Devonian-Upper Devonian contact and 

to the south (location D, fig. 3), silicified Mississippian 

limestone was found to contain detectable (0.7 ppm) 

silver.

Stream sediments and heavy-mineral concentrates 

from drainages near the head of Timpie Valley (area 2) 

also have high values of lead, silver, zinc, and cadmium. 

The minus-30-mesh stream sediments contain as much 

as 50 ppm lead, 2 ppm silver, 100 ppm zinc, and 2.2 ppm

cadmium. Corresponding heavy-mineral-concentrate 

samples contain 500 ppm lead and 5 ppm silver.

Mineralized and altered dolomite collected from a 

small prospect pit in area 2 (location E, fig. 3), which lies 

within the mineralized area from which some mercury 

has been produced (Rigby, 1958), contains up to 7,000 

ppm lead, 30 ppm silver, 10,000 ppm zinc, 22 ppm 

cadmium, 18 ppm antimony, 360 ppm arsenic, and 4 ppm 

bismuth. One sample of dolomite with quartz veins 

contains 300 ppm copper. High concentrations of these 

elements were also found in a small prospect pit 1 mi to 

the northwest (location F) and in loose pieces of rock 

from two small tributaries draining into Timpie Valley 

from the west about 2 mi and 3Vfc mi north of the mercury 

showing (locations G and H respectively, fig. 3).

The geochemical signatures of the samples from 

areas 1 and 2 are similar. The location of these areas 

along the contact between older and younger Paleozoic 

rocks indicates that this contact is a laterally extensive 

zone along which hydrothermal fluids moved and in 

which minerals were locally deposited.

Area 3, northeast of Muskrat Canyon, is 

distinguished by stream-sediment and heavy-mineralconcentrate samples that have a geochemical suite 

consisting of gold, silver, bismuth, antimony, arsenic, 

copper, zinc, and lead. One nonmagnetic heavy-mineral 

concentrate from this area contains 20 ppm gold, 7 ppm 

silver, 70 ppm bismuth, 1,500 ppm antimony, 500 ppm 

copper, and more than 50,000 ppm lead. These high 

values were confirmed with follow-up sampling. Native 

gold, visible with a binocular microscope, was observed in 

concentrate samples from area 3. Although the 

anomalous values of silver, bismuth, and antimony in 

these samples are probably related to the gold, some of 

the lead (and possibly antimony) is clearly due to lead 

shot fragments, which were observed as a contaminant. 

Gold was not detected in the minus-30-mesh sediment 

samples at the lower limit of detection of 0.1 ppm 

(Adrian and others, 1989).

In area 3, loose fragments of silicified and limonitically altered limestone have high concentrations of many 

elements, including 340 ppm arsenic, 470 ppm zinc, 10 

ppm cadmium, and 150 ppm copper, with minor amounts 

of lead, antimony, and bismuth. A sample from a 

silicified fault zone near this area (location I) contained 

anomalous amounts of silver (10 ppm), lead (1000 ppm), 

and zinc (500 ppm). This sample is important because it 

is geochemically similar to the mineralized samples from 

areas 1 and 2 collected near the contact of Lower 

Devonian and older rocks with Upper Devonian and 

younger rocks. This sample, however, is from a fault that 

separates Cambrian limestone and Ordovician shales, 

and indicates that structures other than the Lower 

Devonian-Upper Devonian contact may be mineralized 

within the study area.

North Stansbury Mountains Wilderness Study Area B11
Geophysics Mineral and Energy Resources

Aerial Radiometric Survey

Aerial gamma-ray spectroscopy provides estimates 

of near-surface (0 to 20 inches depth) concentrations of 

potassium, uranium, and thorium. Because the presence 

of uranium and thorium are estimated from 

measurements of their daughter products, their 

abundances are listed as "equivalent" concentrations. 

The data thus provide a partial geochemical 

representation of surface material within the area of the 

survey. Surveys in the Stansbury Mountains were flown 

using a 3-mi flight-line spacing. Reported results (J. 

Duvall, written commun., 1987) show a low to moderate 

overall concentration of radioactivity in the study area, 

indicative of concentrations ranging from 0.8 to 1.6 

percent potassium, 1.0 to 2.5 ppm equivalent uranium, 

and 2 to 6 ppm equivalent thorium. No gamma-ray 

anomalies were observed within or near the study area.

Aeromagnetic Survey

Aeromagnetic surveys flown along eastwest-trending flight lines using a 3-mi spacing and along 

north-south-trending flight lines using a 1-mi spacing 

show no anomalous patterns within the study area (D.L. 

Campbell, written commun., 1987). Although broadly 

spaced, these data should be sufficient to locate a 

moderate size intrusion, if the intrusion contains 

magnetic minerals. Intrusions having prominent 

magnetic signatures occur at Bingham Canyon and other 

mineralized areas in the adjacent Oquirrh Mountains 

(fig. 1), and in the Tintic-Deep Creek belt (about 40 mi 

southeast of the study area). The absence of pronounced 

magnetic anomalies beneath this part of the North Stansbury Mountains indicates that similar large intrusions do 

not occur here.

Regional Gravity Survey

A regional gravity survey that includes the study 

area shows a small gravity high centered near Flux, 

northeast of the study area (fig. 1). The survey also shows 

a small northwest-trending gravity low extending into the 

southeast corner of the study area. However, gravity 

stations in this area are so sparse that this feature is not 

well controlled. In general, the gravity data lack any 

well-defined anomalies within or near the study area 

(D.L. Campbell, written commun., 1987).

Lead, Zinc, Silver, Gold, and Mercury in 

Vein and Replacement Deposits

Good geochemical evidence shows that parts of the 

study area have been mineralized. This mineral 

enrichment is most clearly evident at the mines and 

prospects, most of which are outside but close to the 

eastern margin of the study area (fig. 3). However, a few 

of these prospects do occur within the study area, and 

geochemical anomalies similar to those associated with 

the mines and prospects are also found in the study area.

The mines, prospects, and geochemical anomalies 

are generally on or near the contact separating Lower 

Devonian and older rocks from Upper Devonian and 

younger rocks. This contact most likely an unconformity has clearly acted as a favorable pathway along which 

solutions moved. However, the mineralization in the 

south-central part of the study area (area 3; fig. 3) is not 

near this contact. Particularly, the mineralized sample 

collected from location I (fig. 3) indicates that shears and 

fractures may also have provided effective conduits along 

which mineralizing solutions may have moved. 

Therefore, mineralization was not necessarily confined to 

areas near this contact.

Regionally, the study area lies close to the Oquirrh 

Mountains, which are noted for several large, important 

base- and precious-metal deposits. The large porphyry 

copper deposit at Bingham Canyon is associated with 

vein and replacement deposits consisting of copper, lead, 

and zinc. These deposits typically show a geochemical 

zoning in which copper-rich deposits grade outward to 

those rich in lead and zinc. Concentrations of silver and 

gold may occur in these deposits, and small mercury 

deposits accompany some of the peripheral lead-zinc 

occurrences (Rubright and Hart, 1968).

Vein and replacement deposits also occur in the 

East Tintic Mountains, about 55 miles southeast of the 

study area. These deposits show a zoning from ores rich 

in copper and gold, outward through those richer in silver 

and lead, to deposits containing abundant zinc. 

Importantly, almost all the gold-rich ores occur as veins 

within the Tintic Quartzite, while the lead- and zinc-rich 

deposits form replacement structures in the overlying 

carbonates (Morris and Levering, 1979).

The association of lead, zinc, gold, silver, and 

mercury in some deposits in the Oquirrh and East Tintic 

Mountains is similar to the geochemical association 

found in this study and strongly indicates a potential for 

similar types of vein and replacement deposits in the 

study area. As is common in the East Tintic district, parts 

of the study area underlain by the Tintic Quartzite may 

contain precious-metal-rich veins that are related to the 

lead-zinc mineralization in the overlying carbonates.

B12 Mineral Resources of Wilderness Study Areas Northwestern Utah
Perhaps the visible gold observed in concentrate samples 

from the south-central part of the area (area 3) is derived 

from veins of this type.

The mineral deposits in the Oquirrh and East 

Tintic Mountains are adjacent to Tertiary intrusions. 

Although such intrusions are not observed in the study 

area, and there is no aeromagnetic evidence for them at 

depth, some small felsic intrusions do occur just outside 

the southeast and south margins of the study area. A 

comparison with the Oquirrh Mountains suggests that 

intrusions would be more likely to occur south of the 

study area, closer to the axis of the Cortez-Uinta uplift.

The mines, prospects, and geochemical anomalies 

within the study area clearly indicate the invasion of 

hydrothermal and mineral-bearing fluids. The presence 

of the small intrusions outside the study area suggests 

that the source for the mineralizing fluids may have been 

from the south or southeast. This source direction 

accords well with the excellent evidence for hydrothermal 

mineralization within the southern and eastern parts of 

the study area. The geochemistry of known deposits and 

geochemical anomalies in these areas is similar to that of 

vein and replacement deposits in the Oquirrh and East 

Tintic Mountains. The southern and eastern parts of the 

study area are, therefore, assigned a moderate potential 

for resources of lead, zinc, silver, gold, and mercury in 

vein and replacement deposits, at certainty level C 

(% 2).

The remaining portion of the study area is 

underlain by carbonates and shales, which may be 

favorable host rocks for replacement and vein deposits. 

Fractures and faults in this area may be mineralized, 

although we have found no specific evidence that they 

are. This area is thus considered to have a low potential 

for lead, zinc, silver, gold, and mercury resources in vein 

and replacement deposits, with a certainty level of B.

Gold in Sediment-Hosted, Disseminated Deposits

The Mercur deposit, in the southern part of the 

adjacent Oquirrh Mountains, is a strata-bound, sediment-hosted, disseminated gold deposit formed by 

hydrothermal replacement of the host Upper Mississippian Great Blue Limestone (Kornze, 1987; Jewell and 

Parry, 1987). The solutions that formed this deposit were 

rich in gold, silver, arsenic, antimony, and mercury 

(Lenzi, 1973). At Mercur, the gold occurs as submicroscopic particles disseminated in discontinuous stratabound orebodies.

The Great Blue Limestone crops out along the 

southeastern margin of the study area. Anomalous values 

of silver, arsenic, antimony, and bismuth are found in the 

south-central and eastern parts of the study area (areas 1, 

2, and 3; fig. 3). Mercury analyses were not obtained for 

samples collected inside the study area, but the mercury

occurrence in area 2 (fig. 3) indicates that it is 

concentrated locally. A sample of mercury-rich breccia 

from this area also contained 75 parts per billion gold.

High gold values are associated with visible gold in 

panned concentrates from one drainage in the southcentral part of the study area (area 3). While the 

occurrence of gold is significant, it may not be direct 

evidence for disseminated gold deposits, because gold in 

deposits of this type is generally so fine grained that it is 

not visible even under most microscopes.

In an area that contained disseminated gold 

deposits, fine-grained sediments would probably have the 

highest gold concentrations. Gold was not detected in any 

of the stream-sediment samples, but the analytical 

method used in this study has a lower limit of detection 

for gold in the stream-sediment samples of 0.1 ppm. 

Significant concentrations of less than 0.1 ppm would, 

therefore, not be detected. For this reason, the gold data 

are inconclusive and other indicator elements must be 

used in evaluating the potential for disseminated gold 

deposits.

The strong association of arsenic, antimony, and, 

locally, mercury in areas underlain by carbonate rocks 

and shale could be evidence for occurrences of sedimenthosted gold. Therefore, based on the geochemical 

association and distribution of rock units, the southern 

and eastern parts of the study area, except where 

underlain by Cambrian Tintic Quartzite, are assigned a 

moderate potential for undiscovered sediment-hosted, 

disseminated gold resources, at a certainty level of B (fig. 

2). The other parts of the study area are assigned a low 

potential for resources of this type, with a certainty level 

ofB.

Geothermal Resources

Warm springs occur in both Skull and Tooele 

Valleys at the north end of the Stansbury Mountains. The 

southwest part of the study area extends into Skull Valley 

and thus probably contains thermal waters. However, no 

geothermal resources have been identified in this area 

(Utah Geological and Mineralogical Survey, 1980). The 

potential for geothermal resources in this area is rated as 

moderate with a certainty level of B.

Oil and Gas

The potential for oil and gas resources in the study 

area is considered to be low, but the level of certainty, 

level B, is also low. Most current thinking suggests that 

the absence of recognized good source rocks, the 

fragmentation due to basin and range faulting, and the 

proximity to young intrusive rocks make rocks in this area 

poor prospects for oil and gas. Molenaar and Sandberg

North Stansbury Mountains Wilderness Study Area B13
(1983, p. K12), for example, rated the petroleum 

potential of the study area as "low." They cite fossil 

evidence (thermal alteration of conodonts) that indicates 

Paleozoic source rocks were subjected to temperatures 

that would generate hydrocarbons ranging from mature 

to overmature. However, these factors may not preclude 

the accumulation of hydrocarbons in some of the 

younger rocks along the west edge of the study area. It is 

also quite possible that further work will show some of 

these assumptions to be invalid.

REFERENCES CITED

Adrian, B.M., Duttweiler, KA., Gaccetta, J.D., and Fey, D.L., 

1989, Analytical results and sample locality map of 

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

samples from the North Stansbury Mountains 

Wilderness Study Area, Utah: U.S. Geological Survey 

Open-File Report 88-520.

Almquist, C.L., 1987, Mineral investigation of a part of the 

North Stansbury Mountains Wilderness Study Area 

(UT-020-089), Tooele County, Utah: U.S. Bureau of 

Mines Open-File Report MLA 49-87, 24 p., 1 pi.

Buranek, A.M., 1942, Initial report on the Lead Ore mine, 

Tooele County, Utah: Utah Department of Publicity and 

Industrial Development Circular 9, 5 p.

Butler, B.S., Loughlin, G.F., Heikes, V.C., and others, 1920, 

The ore deposits of Utah: U.S. Geological Survey 

Professional Paper 111, 672 p.

Davis, B.L., 1959, Petrology and petrography of the igneous 

rocks of the Stansbury Mountains, Tooele County, Utah: 

Brigham Young University Research Studies Geology 

Series, v. 6, no. 2, 56 p.

Foose, Michael P., in press, Geologic map of the North 

Stansbury Mountains Wilderness Study Area, Tooele 

County, Utah: U.S. Geological Survey Miscellaneous 

Field Studies Map MF-2061.

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

reports on public lands: U.S. Geological Survey OpenFile Report 84-787, 42 p.

Jewell, P.W., and Parry, W.T., 1987, Geology and hydrothermal 

alteration of the Mercur gold deposit, Utah: Economic 

Geology, v. 82, p. 1958-1966.

John, B.C., 1975, Mineral zones of the Bingham district, in 

Bray, R.E., and Wilson, J.C., eds., Guidebook to the 

Bingham mining district; Society of Economic Geologists 

Field Conference, Bingham Canyon, Utah, October 23, 

1975: Lancaster, Pa., Economic Geology Publishing Co., 

p. 59-72.

Kornze, L.D., 1987, Geology of the Mercur gold mine, in 

Johnson, J.L., ed., Bulk mineable precious metal deposits 

of the Western United States: Geological Society of 

Nevada Guidebook, 1987 Symposium, p. 381-389.

Lenzi, G.W., 1973, Geochemical reconnaissance at Mercur, 

Utah: Utah Geological and Mineralogical Survey Special 

Studies, no. 43, 16 p.

Molenaar, C.M., and Sandberg, CA., 1983, Petroleum 

potential of wilderness lands in Utah, in Miller, B.M., ed.,

Petroleum potential of wilderness lands in the Western 

United States: U.S. Geological Survey Circular 902 A-P, 

p. K1-K14.

Moore, WJ., and McKee, E.H., 1983, Phanerozoic magmatism 

and mineralization in the Tooele 1° x 2° quadrangle, 

Utah, in Miller, D.M., Todd, V.R., and Howard, KA., 

eds., Tectonic and stratigraphic studies in the eastern 

Great Basin: Geological Society of America Memoir 157, 

p. 183-190.

Moore, WJ., and Sorensen, M.L., 1979, Geologic map of the 

Tooele 1° by 2° quadrangle, Utah: U.S. Geological 

Survey Miscellaneous Investigation Series Map 1-1132, 

scale 1:250,000.

Morris, H.T., and Lovering, T.S., 1979, General geology and 

mines of the East Tintic mining district, Utah and Juab 

Counties, Utah: U.S. Geological Survey Professional 

Paper 1024, 203 p.

Rigby, J.K., 1958, Geology of the Stansbury Mountains, eastern 

Tooele County, Utah: Utah Geological Society 

Guidebook to the Geology of Utah, no. 13, p. 1-133.

Rubright, R.D., and Hart, O.J., 1968, Non-porphyry ores of the 

Bingham district, Utah, in Ridge, J.D., ed., Ore deposits 

of the United States, 1933-1967 (Graton-Sales Volume): 

New York, American Institute of Mining, Metallurgical, 

and Petroleum Engineers, v. 1, p. 886-907.

Smith, W.H., 1975, General structural geology of the Bingham 

mining district, in Bray, R.E., and Wilson, J.C., eds., 

Guidebook to the Bingham mining district; Society of 

Economic Geologists Field Conference, Bingham 

Canyon, Utah, October 23, 1975: Lancaster, Pa., 

Economic Geology Publishing Co., p. 41-48.

Sorensen, M.L., 1982, Geologic map of the Stansbury Roadless 

Area, Tooele County, Utah: U.S. Geological Survey 

Miscellaneous Field Studies Map MF-1353-A, scale 

1:62,500.

Tooker, E.W., 1983, Variations in structural style and 

correlation of thrust plates in the Sevier foreland thrust 

belt, Great Salt Lake area, Utah, in Miller, D.M., Todd, 

V.R., and Howard, KA., eds., Tectonic and stratigraphic 

studies in the eastern Great Basin: Geological Society of 

America Memoir 157, p. 61-73.

Tooker, E.W., and Roberts, RJ., 1971, Structures related to 

thrust faults in the Stansbury Mountains, Utah, in 

Geological Survey research 1971: U.S. Geological Survey 

Professional Paper 750-B, p. B1-B12.

U.S. Bureau of Mines, 1924-1931, Mineral resources of the 

United States [annual volumes for the years indicated].

___ 1932-1948, Minerals yearbook [annual volumes for the

years indicated]. 

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, 1917-1923, Mineral resources of the

United States [annual volumes for the years indicated]. 

Utah Geological and Mineralogical Survey, 1980, Geothennal

resources of Utah, 1980: scale 1:500,000.

B14 Mineral Resources of Wilderness Study Areas Northwestern Utah
APPENDIX
DEFINITION OF LEVELS OF MINERAL RESOURCE POTENTIAL 

AND CERTAINTY OF ASSESSMENT

Definitions of Mineral Resource Potential

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 unlikely. This broad 

category embraces areas with dispersed but insignificantly mineralized rock as well as areas with few 

or no indications of having been mineralized.

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 a reasonable likelihood of resource accumulation, and (or) where an application of 

mineral-deposit models indicates favorable ground for the specified type(s) of deposits.

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.

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

moderate, or high levels of resource potential.

NO mineral resource potential is a category reserved for a specific type of resource in a well-defined 

area.

Levels of Certainty

U/A

UNKNOWN

POTENTIAL

H/B

HIGH POTENTIAL

M/B 

MODERATE POTENTIAL

L/B

LOW

POTENTIAL

H/C

HIGH POTENTIAL

M/C 

MODERATE POTENTIAL

L/C

LOW

POTENTIAL

H/D

HIGH POTENTIAL

M/D 

MODERATE POTENTIAL

L/D

LOW POTENTIAL

N/D

NO POTENTIAL

B C 

LEVEL OF CERTAINTY

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

B. Available information 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.

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.
RESOURCE/RESERVE CLASSIFICATION

IDENTIFIED RESOURCES

Demonstrated

Measured Indicated

Inferred

UNDISCOVERED RESOURCES

Probability Range 

Hypothetical i Speculative

ECONOMIC

MARGINALLY 

ECONOMIC

SUBECONOMIC

I

Reserves Inferred Reserves

Marginal Reserves

Demonstrated 

Subeconomic Resources

Inferred 

Marginal Reserves

Inferred

Subeconomic

Resources

Major elements of mineral resource classification, excluding reserve base and inferred reserve base. Modified from McKelvey,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 s resource/reserve classification for minerals: U.S. Geological Survey Circular 831, p.6.
GEOLOGIC TIME CHART 

Terms and boundary ages used in this report

EON

Phanerozoic

Proterozoic

Archean 

pre-Ar<

ERA

Cenozoic

Mesozoic

Paleozoic

Late Proterozoic

Middle Proterozoic

Early Proterozoic

Late Archean

Middle Archean

Early Archean 

jhean2

PERIOD

Quaternary

Tertiary

Neogene 

Subperiod

Paleogene 

Subperiod

Cretaceous

Jurassic

Triassic

Permian

Carboniferous 

Periods

Pennsylvanian

Mississippian

Devonian

Silurian

Ordovician

Cambrian

 3800? -

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

 -

BOUNDARY AGE 

IN 

MILLION YEARS

-0.010

- t.7

- 5

- %

_ KR

_ cc

- 96

I«5O

_ OAC

»*'!

-A, 240

- 290

- f\* ?1fl

_ oen

- 410

- 435

WWW

-~ 570 1

9UU

- 1600

J-3W

-3000 

- idnn

1 Rocks older than 570m.y. also called Precambrian, a time term without specific rank. 

1 Informal time term without specific rank.

t-Y U.S. GOVERNMENT PRINTING OFFICE: 1989-673-047/86092
SELECTED SERIES OF U.S. GEOLOGICAL SURVEY PUBLICATIONS

Periodicals

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