Mineral Resources of the East Fork High Rock 

Canyon Wilderness Study Area, 

Washoe and Hurnboldt Counties, Nevada

U.S. GEOLOGICAL SURVEY BULLETIN 1707-B

Chapter B

Mineral Resources of the

East Fork High Rock Canyon

Wilderness Study Area,

Washoe and Humboldt Counties, Nevada

By JAVA. ACH, DONALD PLOUFF, and ROBERT L.TURNER 

U.S. Geological Survey

STEVEN W. SCHMAUCH 

U.S. Bureau of Mines

U.S. GEOLOGICAL SURVEY BULLETIN 1707

MINERAL RESOURCES OF WILDERNESS STUDY AREAS: 

NORTHWESTERN NEVADA
DEPARTMENT OF THE INTERIOR 

DONALD PAUL MODEL, Secretary

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1987

For sale by the

Books and Open-File Reports Section

U.S. Geological Survey

Federal Center, Box 25425

Denver, CO 80225

Library of Congress Cataloging-in-Publication Data

Mineral resources of the East Fork High Rock Canyon 

Wilderness Study Area, Washoe and Humboldt Counties, 

Nevada.

U.S. Geological Survey Bulletin 1707-B 

Bibliography

jSupt. of Docs. No.: I 19.3:1707-6 

1. Mines and mineral resources Nevada East Fork High 

Rock Canyon Wilderness. 2. East Fork High Rock Canyon 

Wilderness (Nev.) I. Ach, Jay A. . II. Series.

QE75.B9 No. 1707-B 557.3 s 87-600382 

[TN24.N3] [553'.09793'54]
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 part of the East Fork High Rock Canyon 

Wilderness Study Area (CA 020-914/NV-020-006A), Washoe and Humboldt Counties, Nevada.

CONTENTS

Summary Bl

Abstract 1

Character and setting 1

Identified resources 1

Mineral resource potential 1 

Introduction 3

Area description 3

Previous and present investigations 3

Acknowledgments 3 

Appraisal of identified resources 4 

Assessment of mineral resource potential 5

Geology 5

Geophysical studies 6

Geochemical studies 8

Mineral and energy resources 8 

References cited 9 

Appendixes

Definition of levels of mineral resource potential and certainty of 

assessment 13

Resource/reserve classification 14

Geologic time chart 15

FIGURES

1. Index map showing location of the East Fork High Rock Canyon Wilderness Study Area, Washoe and 

Humboldt Counties, Nevada B2

2. Mineral resource potential and geology of the East Fork High Rock Canyon Wilderness Study Area, 

Washoe and Humboldt Counties, Nevada 4

3. Gravity map of the East Fork High Rock Canyon Wilderness Study Area, Washoe and Humboldt 

Counties, Nevada 7

MINERAL RESOURCES OF WILDERNESS STUDY AREAS: 

NORTHWESTERN NEVADA

Mineral Resources of the

East Fork High Rock Canyon

Wilderness Study Area,

Washoe and Humboldt Counties, Nevada

By Jay A. Ach, Donald Plouff, and Robert L. Turner 

U.S. Geological Survey

Steven W. Schmauch 

U.S. Bureau of Mines

SUMMARY 

Abstract

The part of the East Fork High Rock Canyon Wilderness Study Area (CA-020-914/NV-020-006A) included in this 

study encompasses 33,460 acres in the northwestern part of 

Nevada. Throughout this report, "wilderness study area" and 

"study area" refertothe 33,460 acres for which mineral surveys 

were requested. The U.S. Geological Survey and the U.S. 

Bureau of Mines conducted geological, geophysical, and geochemical surveys to assess the mineral resources (known) 

and the mineral resource potential (undiscovered) of the study 

area. Fieldwork for this report was carried out in 1985 and 

1986. No mines, significant prospects, or mining claims are 

located inside the study area, and no identified resources were 

found. The wilderness study area has moderate mineral 

resource potential for gold, silver, and mercury and for zeolite 

minerals. A low potential also exists for geothermal energy 

resources, and potential for oil and gas is unknown.

Character and Setting

The East Fork High Rock Canyon Wildernesss 

Study Area is located approximately 25 mi east-southeast of 

Vya, in the northwestern part of Nevada (fig. 1). Rolling hills 

and gentle slopes are typical of most of the study area. The

western part of the study area is deeply incised by canyons and 

the eastern part includes several small buttes.

The Soldier Meadow Tuff, a rhyolitic tuff, is the 

oldest exposed unit in the study area. Canyons and streamcuts 

reveal air-fall tuff and lacustrine sediments overlying the 

Soldier Meadow tuff. The air-fall tuffs and sediments were 

intruded by rhyolite domes. In the central, relatively flat part 

of the study area, the tuffs and sedimentary rocks are overlain 

by several thin, dark andesite to dacite flows. Geophysical 

evidence indicates that the study area may be located over the 

ring fracture of a caldera system.

Identified Resources

No identified mineral or energy resources exist in the 

study area and the area does not lie in any established mining 

district. No known mines or mining claims are located within 

the study area. The only known prospect is in barren rock.

Mineral Resource Potential

Two areas in the northern and western part of the 

study area have moderate mineral resource potential for gold, 

silver, and mercury in epithermal deposits. Evidence for this 

potential is provided by geochemical anomalies and areas of 

slightly altered rock. Part of the ring fracture system of a 

caldera may pass through the area; such fractures, if they exist, 

could have provided conduits for hydrothermal mineralizing 

fluids.

East Fork High Rock Canyon Wilderness Study Area B1
1 20°00' 1 19°45' 1 19°00'

- LAKE C0 

WASHOE CO HUMBOLDT CO

APPROXIMATE BOUNDARY

OF

EAST FORK HIGH ROCK CANYON 

WILDERNESS STUDY AREA 

(CA 020-914/NV 020-006 A)

AREA OF MAP 

41°00' I

Figure 1. Index map showing location of the East Fork High Rock Canyon Wilderness Study Area, Washoe and 

Humboldt Counties, Nevada.

B2 Mineral Resources of Wilderness Study Areas Northwestern Nevada
One area along the west boundary of the study area 

has moderate resource potential for zeolite minerals. Evidence for this potential is provided by the occurrence of these 

minerals west of the study area in altered tuffaceous rocks 

(Turrin and others, 1987) that extend into the study area.

Due to the presence of hot springs 5 mi to the east, the 

study area has a low potential for geothermal energy resources. No evidence of recent geothermal activity in the 

study area has been found. Potential for oil and gas resources 

is unknown.

INTRODUCTION

This mineral resource study is a joint effort by the 

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

Mineral assessment methodology and terminology are discussed in Goudarzi (1984). Identified resources are classified 

according to the the system described by the U.S. Bureau of 

Mines and the U.S. Geological Survey (1980). See the 

appendix for the definition of levels of mineral resource 

potential, certainty of assessment, and classification of identified resources. 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 geochemical 

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 33,460 acres of the East Fork High Rock Canyon Wilderness Study Area (CA-020-914/NV-020-006A) be evaluated 

for mineral resource potential. The study area is about 47 mi 

southeast of the northwestern comer of Nevada and approximately 25 mi east-southeast of Vya (fig. 1). A small, sloping 

plateau deeply incised on the west side by the precipitous High 

Rock and Pole Canyons is the dominant topographic feature 

of the area. In places the canyons have sheer cliffs 500 ft high 

and a total depth approaching 800 ft. In the eastern part of the 

study area, erosion has sculpted numerous small buttes. High 

Rock Lake, a year-round lake, is located 1 mi south of the 

wilderness study area and provides a haven for migratory 

waterfowl. Antelope, wild horses, and coyotes are the larger 

mammalian residents of the study area. The climate is arid to 

semiarid, with an average of less than 10 in. of precipitation a 

year (Sthraler, 1969). The vegetation is sparse, consisting of 

sagebrush, various range grasses, and a solitary juniper tree.

Access to the study area from the southwest is 

provided by approximately 13 mi of unimproved jeep trails

from Nevada Route 34. The study area can also be reached 

from the north by Nevada Route 8A via approximately 17 mi 

of jeep trails. Jeep trails pass through High Rock Canyon 

along the historic Lassen-Applegate Trail of the mid to late 

1800's.

Previous and Present Investigations

Bonham (1969) provided a good description of the 

geology of the High Rock area. Willden (1964) wrote a 

geological overview of neighboring Humboldt County. 

Korringa (1973), Korringa and Noble (1970), and Noble and 

others (1970,1973) studied the Soldier Meadow Tuff, which 

crops out in the eastern part of the study area.

Previous reconnaissance studies of the geology and 

mineral resources of wilderness study areas in the region were 

carried out by Barringer Resources, Inc. (1982). The uranium 

resource potential for the region was evaluated as part of the 

U.S. Department of Energy National Uranium Resource 

Evaluation (NURE) program (Geodata International, 1979).

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

1986. This work included geologic mapping and geochemical 

sampling. Eighty-six rock samples and 43 stream-sediment 

samples were collected and analyzed. Rock samples were 

collected from areas of altered bedrock and from each lithologic unit in order to obtain information on trace-element 

signatures associated with potentially mineralized areas and 

to provide data on background trace-element concentrations.

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

for information on mines and prospects within the study area. 

Additional data were obtained from records of Washoe and 

Humboldt Counties, the U.S. Bureau of Land Management, 

and the U.S. Bureau of Mines. Field studies by U.S. Bureau 

of Mines personnel were carried out in 1985 (Schmauch, 

1986). Forty-five rock samples were collected from areas of 

possible mineral concentrations within and immediately outside the study area. Samples were analyzed by fire-assay, 

atomic-absorption, and inductively coupled argon-plasma 

spectrophotometric methods. 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

James T. Bateson provided able assistance with the 

geologic mapping. Joseph McFarlan, geologist, and the staff 

of the Cedarville, Calif., District Office of the U.S. Bureau of 

Land Management provided logistical support, information, 

and the use of the Bureau's facilities at Stevens Camp. Dr. 

D.C. Noble, professor at the University of Nevada, Reno, led 

an informative field trip for U.S. Bureau of Land Management 

and U.S. Geological Survey geologists to the study area and 

the surrounding region.

East Fork High Rock Canyon Wilderness Study Area B3
APPRAISAL OF IDENTIFIED RESOURCES

By Steven W. Schmauch 

U.S. Bureau of Mines

No identified mineral resources exist in the East Fork 

High Rock Canyon Wilderness Study Area. The study area 

does not lie in an established mining district and no records of 

historical or active claims exist. The closest mining district,

the Leadville district, is located about 30 mi south of the study 

area.

The Hog Ranch Mountain gold mine, currently 

being brought into production, is located approximately 17 mi 

south-southwest of the study area. This epithermal deposit 

consists of an estimated 5 million tons of low-grade, heapleachable ore in silicified rhyolite host rocks (Harvey and 

others, 1986).

Approximately six miles north of the study area, 46 

gold-silver-mercury claims (the GRE claims) were main119"22- 3Cr

41"27'30"

Au, Ag> Hg 

[L2] V

(Entire study area)

APPROXIMATE BOUNDARY | OF

EAST FORK HIGH ROCK CANYON 

WILDERNESS STUDY AREA 

. (CA-020-914/NV-020-006A)

Figure 2. Mineral resource potential and geology of the East Fork High Rock Canyon 

Wilderness Study Area, Washoe and Humboldt Counties.

B4 Mineral Resources of Wilderness Study Areas Northwestern Nevada
tained in 1984 by Tenneco. At this site mercury occurs in 

cinnabar in massive opal and opalized rhyolite breccia. 

Concentrations of mercury in two samples from these claim 

areas are 120 ppm and 330 ppm; concentrations of gold and 

silver are low (Scott, 1987).

The study area was examined for site-specific indications of possible hydrothermal-epithermal precious-metal 

deposits. Diagnostic features of this type of deposit, including 

large areas of intense silicification, quartz fissure veins, silicic 

or argillic wallrock alteration, or fractured, favorable host 

rocks, were not observed. Slightly altered tuffs, possible 

indicators of former hydrothermal activity, occur in Yellow 

Rock Canyon and the Yellow Hills.

A part of a zeolite-bearing altered tuff is exposed in 

a canyon wall near Yellow Rock Canyon. West of High Rock 

Canyon, larger areas of this unit are exposed at the surface 

(Scott, 1987).

Small accumulations of sand and gravel in the study 

area have no unique commercial characteristics and larger 

supplies are more readily available closer to market areas.

ASSESSMENT OF MINERAL RESOURCE 

POTENTIAL

By Jay A. Ach, Donald V. Plouff, and Robert L Turner 

U.S. Geological Survey

EXPLANATION

H Area with moderate mineral resource potential

Area with low mineral resource potential

See appendix for definition of levels of mineral resource potential 

and certainty of assessment

Au 

Ag

Hg

Zeo

Geo

Commodities

Gold 

Silver 

Mercury 

Zeolites 

Geo thermal

[ 1 Deposit types

1 Epithermal or hot-spring deposits of gold and silver in 

volcanic and volcaniclastic rocks

2 Epithermal mercury deposits in volcanic and 

volcaniclastic rocks

Geologic map units

Qal Alluvium (Quaternary)

Ts Lacustrine sedimentary rocks (Tertiary)

Tad Andesite to dacite flows and dikes (Tertiary)

Tr Rhyolite flows, domes, and dikes (Tertiary)

Tt Air-fall tuff (Tertiary)

Tsm Soldier Meadow Tuff (Tertiary)

 Contact Dashed where approximate 

_1 ... Normal fault Dashed where approximate, dotted 

where concealed; bar and ball on downthrown side

 Intermittent stream

Figure 2. Continued.

Geology

Pre-Miocene basement rocks are not exposed within 

or near the East Fork High Rock Canyon Wilderness Study 

Area but are inferred to be Mesozoic granites or metamorphic 

rocks. Cretaceous granites are exposed 13 mi east of High 

Rock Lake in the Black Rock Range, and granites of similar 

age intrude Triassic and (or) Jurassic metamorphosed sedimentary rocks in the southern Calico Mountains 15 mi south 

of High Rock Lake.

The oldest unit exposed in the study area is the 

middle Miocene Soldier Meadow Tuff (fig. 2). Reported 

radiometric ages for this unit are between 14.7±0.5 Ma (million years) and 15.611.7 Ma (Noble and others, 1970; Marvin 

and others, 1970; Noble and others, 1973). This unit is 

composed of lava flows and ash flows of peralkaline rhyolite 

(comendite). The tuff is light gray to light tan and contains less 

than 25 percent total phenocrysts of smokey quartz, sanidine 

(commonly chatoyant), and minor sodic amphibole, iron-rich 

clinopyroxene, and vapor-phase arfvedsonite. Korringa and 

Noble (1970) indicate that the Soldier Meadow Tuff was 

erupted from a linear series of vents at the west edge of Soldier 

Meadow, a few miles east of the study area. Gravity data 

presented in this paper indicate that these vents may lie along 

a caldera ring fracture.

A light-bluish-gray to light-gray, pumiceous, nonwelded air-fall tuff conformably overlies the Soldier Meadow 

Tuff. This unit is composed of approximately 80 percent 

uncollapsed pumice fragments in a matrix of ash. Sparse 

sanidine, quartz, and plagioclase phenocrysts are present in 

the pumice fragments and the matrix. Small clasts of Soldier 

Meadow Tuff are common in this unit; in a few localities these 

clasts reach a diameter of 4 to 5 ft. Parts of this unit may be 

water-lain, and in places the upper part has been reworked by 

water. The unit has been altered to light mustard yellow in 

Yellow Rock Canyon, east of the study area; a small amount 

of altered rock of this type is exposed within the study area 

near the junction of Yellow Rock and High Rock Canyons. A 

thin rhyolite obsidian that overlies the pumiceous tuff gives a

East Fork High Rock Canyon Wilderness Study Area B5
potassium-argon age of 15.3±0.5 Ma (Noble and others, 

1973).

The pumiceous air-fall tuff has been intruded by a 

light-gray to light-purplish-gray rhyolite. Similar rhyolites 

nearby give apotassium-argon age of 15.1±0.5 Ma (Noble and 

others, 1973). Sparse sanidine, aegirine, and soda-amphibole 

are the phenocryst phases in this unit. Small zones of vaporphase alteration are common. Whole-rock geochemistry (J. A. 

Ach, unpub. data, 1986) indicates that this rhyolite is metaluminous/peraluminous in composition, but on the basis of 

vapor-phase mineralogy, Noble and others (1973) consider 

this rhyolite to be peralkaline (a comendite). Sodium loss 

upon cooling is common in peralkaline rhyolites (Noble, 

1970); for this rock, the loss of only 0.15 percent sodium upon 

cooling would resolve the apparent conflict between chemistry and mineralogy.

Tuffaceous lacustrine sedimentary rocks crop out at 

both the north and south ends of the study area and probably 

overlie the pumiceous tuff. These rocks are white to light gray 

and fine to very fine grained. In the southern part of the area, 

they contain middle Miocene vertebrate fossils (Carl S wisher, 

oral comm., 1986), and a thin layer of tuff overlying the 

sediments gives potassium-argon ages of 14 Ma (Carl 

Swisher, oral commun., 1986). The sedimentary rocks in the 

northern part of the area have similar lilhologies and probably 

are middle Miocene as well.

Several dark, 5- to 25-ft-thick lava flows form the 

flat surface in the central part of the study area and cap the 

buttes in the eastern part. These flows weather to a rusty 

brown, but are bluish to purplish black on freshly broken 

surfaces. Upper surfaces of the flows are vesiculated. These 

flows are extremely phenocryst poor, with only rare sanidine 

and clinopyroxene observed. Whole-rock chemical analyses 

(Ach, unpub. data, 1986) indicate that these flows are highpotassium andesites and dacites (banakites). No radiometric 

ages have been reported for this unit; it probably is also middle 

Miocene in age.

Quaternary deposits consist of alluvium in the canyon bottoms, talus on canyon slopes, and local landslide 

deposits along the canyon sides.

North-northwest-trending basin-and-range faults 

occur along High Rock and Pole Canyons and in the northern 

part of the study area. Vertical offsets along these faults are 

typically between 25 and 200 ft.

Geophysical Studies

Geophysical surveys of the study area have used 

aerial gamma-ray, aeromagnetic, and gravity techniques.

Radiometric data were compiled by Geodata International, Inc. (1979), for the U.S. Department of Energy 

National Uranium Resource Evaluation (NURE). Three eastwest flightlines totalling about 12 mi in length and separated 

by about 3 mi recorded gamma-ray flux from radioactive 

isotopes of uranium, thorium, and potassium. Flight altitudes

above the ground level varied from 300 to 400 ft over most of 

the study area but exceeded 1,000 ft over High Rock Canyon. 

The flux level of potassium is about the same as in surrounding 

areas along the profiles. However, the flux levels of uranium 

and thorium isotopes are fairly constant and low compared 

with adjacent areas, except in alluvium-covered valleys. The 

uniformly low values for uranium and thorium may reflect 

rock alteration.

An aeromagnetic drape survey was flown to provide 

detailed magnetic data for evaluation of the resource potential 

of the study area (U.S. Geological Survey, 1985). Northsouth flightlines spaced at intervals of 0.5 mi were flown at 

altitudes of about 1,000 ft above the mean ground surface. 

Twelve elongate magnetic lows that have long dimensions 

ranging from 0.5 to 2.0 mi are scattered throughout the study 

area. Magnetic lows overlie hilltops and magnetic highs 

commonly overlie canyons. This inverse correlation of 

magnetic anomalies with topography indicates that the source 

rocks for the magnetic lows are reversely magnetized and are 

at or near the ground surface. This effect is further exaggerated because flight altitudes tended to decrease closer to the 

reversely magnetized rocks over hillcrests and to increase 

more than 1,000 ft above canyons.

The reversely magnetized source rocks consist 

mostly of high-potassium andesite to dacite flows that are 

prevalent at the surface. Some of the intense magnetic lows 

may indicate andesite/dacite vent areas. The rhyolite exposed 

to the southeast of the confluence of Pole and High Rock 

Canyons is not correlated with a magnetic anomaly, indicating the rhyolite is weakly magnetized. A conspicuous magnetic high, about 2.5 mi in diameter, overlies the Yellow Hills 

along the north edge of the study area, indicating rocks of 

normal magnetization at or beneath the surface in that area.

Gravity studies were based on data from 18 U.S. 

Geological Survey gravity stations in the study area and an 

additional 27 stations within 3 mi of the boundary. The 

stations were established during 1984 and 1985. These data 

were supplemented by published gravity data from 7 stations 

(National Geophysical Data Center, 1984).

The gravity minimum of a large gravity low covers 

a 3- by 6-mi area in the northeast corner of the study area (fig. 

3). Bouguer gravity anomaly values increase 22 milligals 

(mGal) southward from the gravity minimum and 8 mGal 

southwestward from theminimum to theedgeof the larger 12- 

by 30-mi gravity low. The northern part of this large gravity 

low was interpreted by Greene and Plouff (1981) as a caldera 

filled with and concealed beneath younger flat-lying sediments and volcanic rocks. The entire large gravity low is here 

interpreted to represent either a large single caldera or two or 

more smaller, nested calderas. The gravity low presumably 

results from the density contrast between the less dense 

tuffaceous sedimentary rocks filling the caldera and the 

denser country rocks outside the caldera rim.

Assuming that tuffaceous sedimentary rocks are 0.3 

g/cm3 (grams per cubic centimeter) less dense than rocks 

outside the caldera, 5,740 ft of intracaldera sedimentary rocks

B6 Mineral Resources of Wilderness Study Areas Northwestern Nevada
119'22'30' 119° 17'30'

41'27'30" -

41° 22'30" -

41° 17'30" -

APPROXIMATE BOUNDARY 

OF

EAST FORK HIGH ROCK CANYON 

WILDERNESS STUDY AREA/ 

(CA-020-914/NV-020-006AK

0 0.5 1 MILE

! I I

Figure 3. Gravity map of the East Fork High Rock Canyon Wilderness Study Area, Washoe and Humboldt Counties, 

Nevada. Values in milligals; contour interval 2 milligals; hachured in direction of gravity low.

East Fork High Rock Canyon Wilderness Study Area B7
are needed to account for the 22-mGal amplitude of the 

gravity low (Nettleton, 1940, p. 112). The observed gravity 

gradient of 7.5 mGal/mi in the southern part of the study area 

exceeds a gradient of 6.4 mGal/mi calculated for a model of 

a vertical caldera wall that extends to the surface (Nettleton, 

1940, p. 112). Since the proposed caldera is not exposed at the 

surface, three possibilities could explain this higher-thanexpected gradient: (1) the south wall may dip somewhat 

southward from vertical; (2) the density contrast between the 

underlying former magma reservoir and surrounding basement rocks may contribute to the amplitude of the anomaly; or 

(3) the rocks beneath a gravity high to the south (Keith and 

others, 1987) are denser than Tertiary volcanic rocks in the 

basement on other sides of the caldera. The gravity increase 

to the southwest is only 8 mGal, compared to the 22-mGal 

increase to the south. This smaller increase could be due to 

less relief on the caldera margin (calculated at 2,100 ft) or 

deeper burial of the caldera margin in this area.

Geochemical Studies

A reconnaissance geochemical investigation of the 

study area was made using samples of stream sediment, the 

nonmagnetic fraction of heavy-mineral concentrates from 

stream sediments, and rock. The stream-sediment and concentrate samples contain material derived from major rock 

units of the drainage basins within the study area. Sampled 

drainage basins range in area from less than one to several 

square miles.

Forty-three stream-sediment samples, 43 heavymineral-concentrate samples, and 86 rock samples were analyzed for 31 elements by six-step semiquantitative emissionspec trographic methods (Myers and others, 1961; Grimes and 

Marranzino, 1968), with additional analyses by atomicabsorption spectroscopy and inductively coupled argon 

plasma-atomic emission spectroscopy. These analyses identify drainages that have anomalously high concentrations of 

metallic and metal-related elements. For this study, anomalous geochemical values were determined by inspection of 

histograms of the data from both the study area and the 

surrounding region and by comparing the data to the average 

abundances in silicic volcanic rocks. For most elements, a 

value was considered anomalous if it exceeded the mean value 

for the element by two standard deviations.

In the northwestern and northern parts of the study 

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

samples all have anomalously high concentrations of arsenic. 

Samples of altered rock and chalcedony in this area show high 

concentrations of arsenic but only slight, if any, anomalies in 

their concentrations of mercury, antimony, molybdenum, 

cadmium, and zinc.

Data from Barringer Resources, Inc. (1982), indicates that stream sediments in the eastern part of the study area 

have anomalously high concentrations of barium. No other 

geochemical anomalies and no visibly altered rocks were

observed in this part of the study area, making a hydrothermal 

origin for these anomalies unlikely. These anomalies may 

reflect high levels of barium in the andesite to dacite flows 

(J.A. Ach, unpub. data, 1986).

Previous regional uranium surveys, which included 

aerial gamma-ray emission studies (Geodata International, 

Inc., 1979), found no indications of uranium or thorium 

concentrations near the study area. Available stream-sediment data (Barringer Resources, Inc., 1982) show only very 

slight, scattered anomalies of uranium and (or) thorium, 

supporting these previous conclusions.

Mineral and Energy Resources

The investigations by the U.S. Geological Survey 

and the U.S. Bureau of Mines indicate that the East Fork High 

Rock Canyon Wilderness Study Area has two areas of moderate resource potential for gold and silver in epithermal or 

hydrothermal deposits and mercury in epithermal deposits, 

certainty level C. The resource potential for zeolites is 

moderate with a B certainty level. The resource potential for 

geothermal energy is low, with a C certainty level. The 

resource potential for petroleum and natural gas is unknown 

(certainty level A), but their occurrence within the study area 

is very unlikely.

The potential for gold, silver, and mercury in the 

parts of the study area near Yellow Rock Canyon and in the 

Yellow Hills (fig. 2) is indicated by arsenic anomalies and 

scattered lesser anomalies of mercury, molybdenum, cadmium , antimony, and zinc. In the areas where these anomalies 

are present, the pumiceous air-fall tuff is altered to a mustardyellow color or has partially silicified zones containing chalcedony veins. Together, the geochemical anomalies and the 

alteration suggest probable former hydrothermal activity in 

these areas.

Anomalously high values for arsenic, antimony, 

molybdenum, and mercury are often associated with epithermal hot-spring type gold-silver mineralization (Bonham and 

Giles, 1983; Bonham and Tingley, 1984), epithermal silvergold mineralization of the low-sulfur type (Bonham, 1984; 

Bonham and Tingley, 1984), or epithermal mercury mineralization (Rytuba and Glanzman, 1979), all of which occur in 

silicic volcanic and volcaniclastic host rocks. Important 

mineral deposits of these types are usually associated with the 

complex structures and features found in volcanic eruptive 

centers. These structures and features include strongly persistent fracture systems, especially caldera-relatedring fractures 

and grabens, and volcanic domes and plugs in complexly 

faulted areas (Berger, 1982). Although few mineral deposits 

are directly caldera related (McKee, 1979; Raul Madrid, oral 

commun., 1987), caldera ring fractures, as considered possible in this study area, may form a permissive environment 

for epithermal deposits. Examples of epithermal deposits 

located within caldera systems are the Round Mountain, Nev., 

gold deposit (Bonham and Tingley, 1984), the Creede, Colo.,

B8 Mineral Resources of Wilderness Study Areas Northwestern Nevada
silver-gold base-metal deposits (Barton, 1982), and the mercury, uranium, and lithium deposits found at McDermitt, Ore. 

(Rytuba, 1976).

Accumulations of zeolites are found in the mustardyellow altered part of the pumiceous air-fall tuff in Yellow 

Rock Canyon (Turrin and others, in press), where five 

samples analyzed by the U.S. Bureau of Mines contain 55 to 

80 percent clinoptilolite, a zeolite mineral (Scott, 1987; Turrin 

and others, in press). A similarly altered part of this tuff 

extends into the study area. Therefore the mineral resource 

potential for zeolites in this part of the study area is considered 

moderate with a certainty level B.

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

constitute resource. No undiscovered sand and gravel resources are expected beyond known deposits.

For this study, the resource potential for petroleum 

and natural gas is considered unknown, certainty level A. 

Geologic data indicate a low probability for the occurrence of 

petroleum and natural gas in the Cenozoic rocks of the 

wilderness study area. Evidence for hydrocarbon potential is 

negligible; the volcanic rocks and the limited lacustrine sedimentary strata immediately underlying the study area might 

possibly include suitable reservoir rocks, but lack hydrocarbon source beds. The nature of the basement rocks is conjectural, however. Sandberg (1983) considers the area to have 

"zero petroleum potential" because widespread Miocene 

volcanism and geothermal healing rendered the area too 

thermally mature for the formation of hydrocarbons.

Geothermal energy resource potential for the study 

area is low with a C certainty level. No evidence of recent 

geothermal activity in the study area has been found, but 

several hot springs exist 5 mi east of the study area in the 

Soldier Meadow Known Geothermal Resource Area. Previous regional geothermal surveys have not indicated any geothermal potential for the area (Muffler, 1979; Reed, 1983).

REFERENCES CITED

Barton, Paul, 1982, Silver/base metal epithermal deposits; in 

Erickson, R.L., ed., Characteristics of mineral deposit 

occurrences: U.S. Geological Survey Open-File Report 

82-795, 248 p.

Berger, B.R., 1982, The geological attributes of Au-Ag-base 

metal epithermal deposits; in Erickson, R.L, ad., Characteristics of mineral deposit occurrences: U.S. Geological Survey Open-File Report 82-795, 248 p.

Barringer Resources Inc., 1982, Geochemical and geostatistical evaluation of wilderness study areas, Winnemucca 

district, northwest Nevada, prepared for U.S. Bureau of 

Land Management: Golden, Cob., 5 v., 24 pi., scale 

1:250,000.

Bonham, H.F., 1969, Geology and mineral deposits of

Washoe and Storey Counties, Nevada, with a section on 

Industrial minerals by K.G. Papke: Nevada Bureau of 

Mines and Geology Bulletin 70, 140 p.

Bonham, H.F. Jr., 1984, Three major types of epithermal 

precious-metal deposits [abs.]: Geological Society of 

America Abstracts with Programs, v. 16, no. 6, p. 449.

Bonham, H.F. Jr., and Giles, D.L, 1983, Epithermal gold/silver 

deposits: The geothermal connection: Geothermal 

Resources Council, Special Report No. 13, p. 257-262.

Bonham, H.F. Jr., and Tingley, J.V., 1984, Bulk-minable gold 

deposits in Nevada [abs.]: Geological Society of America Abstracts with Programs, v. 16, no. 6, p. 449.

Geodata International, Inc., 1979, Aerial radiometric and 

magnetic survey, Vya national topographic map, Nevada: U.S. Department of Energy Open-File Report 

GJBX-136(79), v. 2, 73 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.

Greene, R.C., and Plouff, Donald, 1981, Location of a caldera 

source for the Soldier Meadow Tuff, northwestern Nevada, indicated by gravity and aeromagnetic data: 

Geological Society of America Bulletin.-Part 2, v. 92, no. 

1, p. 39-56.

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

PHarvey, D.S., Noble, D.C., and McKee, E.H., 1986, Hog Ranch 

gold property, northwestern Nevada: Age and genetic 

relation of hydrothermal mineralization to coeval peralkaline silicic and associated basaltic magmatism: Isochron/West, no. 47, p. 9-11.

Keith, W.J., Turner, R.L., Plouff, Donald, and Peters, T.J., 

1987, Mineral Resources of the Little High Rock Canyon 

Wilderness Study area, Washoe County, Nevada: U.S. 

Geological Survey Bulletin 1707-C, 17 p.

Korringa, M.K., 1973, Linear vent area of the Soldier Meadow 

Tuff, an ash-flow sheet in northwestern Nevada: Geological Society of America Bulletin, v. 84, p. 3849-3866.

Korringa, M.K., and Noble, D.C., 1970, Ash-flow eruption from 

a linear vent area without caldera collapse [abs.]: Geological Society of America Abstracts with Programs, v. 2, 

p. 108-109.

Marvin, R.F., Mehnet, H.H., and Noble, D.C., 1970, Use of 

argon36 to evaluate the incorporation of air by ash-flows: 

Geological Society of America Bulletin, v. 81, p. 3385- 

3392.

McKee, E.H., 1979, Ash-flow sheets and calderas: their genetic relationship to ore deposits in Nevada: Geological 

Society of America Special Paper 180, p. 205-211.

Muffler, L.J.P., ed., 1979, Assessment of geothermal resources of the United States 1978: U.S. Geological 

Survey Circular 790,163 p.

Myers, AT., Haven, R.G., and Dunton, P.J., 1961, A spectroEast Fork High Rock Canyon Wilderness Study Area B9
chemical method for the semiquantitative analysis of 

rocks, minerals, and ores: U.S. Geological Survey 

Bulletin 1084-1, p. 207-229.

National Geophysical Data Center, 1984, DMA gravity file of 

the U.S.: National Oceanic and Atmospheric Administration, Boulder, Colorado, 2 magnetic tapes.

Nettleton, L.L, 1940, Geophysical prospecting for oil: New 

York, McGraw-Hill Book Co., Inc., 444 p.

Noble, D.C., 1970, Loss of sodium from crystallized comendite 

welded tuffs of the Miocene Grouse Canyon Member of 

the Belted Range Tuff, Nevada: Geological Society of 

America Bulletin, v. 81, p. 2677-2688.

Noble, D.C., McKee, E.H., Smith, J.G., and Korringa, M.K., 

1970, Stratigraphy and geochronology of Miocene rocks 

in northwestern Nevada: U.S. Geological Survey Professional Paper 700-D, p. D23-D32.

Noble, D.C., Hedge, C.E., McKee, E.H., and Korringa, M.K., 

1973, Reconnaissance study of the strontium isotopic 

composition of Cenozoic volcanic rocks in the northwestern Great Basin: Geological Society of America Bulletin, 

v. 84, p. 1393-1406.

Reed, M.J., ed., 1983, Assessment of low-temperature geothermal resources of the United States 1982: U.S. 

Geological Survey Circular 892, 73 p.

Rytuba, J.J., 1976, Geology and ore deposits of the McDermitt 

Caldera, Nevada-Oregon: U.S. Geological Survey 

Open-File Report 76-535, 9 p.

Rytuba, J.J., and Glanzman, R.K., 1979, Relation of mercury, 

uranium, and lithium deposits to the McDermitt Caldera 

Complex, Nevada-Oregon, in Ridge, J.D., ed., Papers

on mineral deposits of western North America: Nevada 

Bureau of Mines and Geology Report 33, p. 109-117.

Sandberg, C.A., 1983, Petroleum potential of Wilderness 

lands in Nevada, in Miller, B.M., ed., Petroleum potential 

of Wilderness lands in the western United States: U.S. 

Geological Survey Circular 902[A-P], p. H1-H11.

Schmauch, S.W., 1986, Mineral Resources of the East Fork 

High Rock Canyon Study Area, Humboldt and Washoe 

Counties, Nevada: U.S. Bureau of Mines Mineral Lands 

Assessment MLA 60-86, 9 p.

Scott, D.F., 1987, Mineral Resources of the High Rock Canyon 

Study Area, Washoe County, Nevada: U.S. Bureau of 

Mines Mineral Lands Assessment MLA 14-87,18 p.

Sthraler.A., 1969, Physical Geography: New York, John Wiley 

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

Turrin, B.D., Bergquist, J.R., Plouff, Donald, Ponader, C.W., 

and Scott, D.F., in press, Mineral Resources of the High 

Rock Canyon Wilderness Study Area, Washoe County, 

Nevada: U.S. Geological Survey Bulletin 1707-D.

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, 1985, Aeromagnetic map of the High 

Rock Lake area, northwestern Nevada: U.S. Geological 

Survey Open-File Report 85-751, 1 sheet, scale 

1:62,500.

Willden, R., 1964, Geology and mineral deposits of Humboldt 

County, Nevada: Nevada Bureau of Mines Bulletin 59, 

154 p.

B10 Mineral Resources of Wilderness Study Areas Northwestern Nevada
APPENDIXES
DEFINITION OF LEVELS OF MINERAL RESOURCE POTENTIAL 

AND CERTAINTY OF ASSESSMENT

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 

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 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 occurence, where interpretations of 

data indicate a high degree of likelihood for resource accumulation, where data supports 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

t

O 

Q.

CJ 

CC

O 

C/>

LU

cc

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.

B12 Mineral Resources of Wilderness Study Areas Northwestern Nevada
RESOURCE/RESERVE CLASSIFICATION

ECONOMIC

MARGINALLY 

ECONOMIC

SUBECONOMIC

IDENTIFIED RESOURCES

Demonstrated

Measured

Res( 

i_

Indicated

srves

r~

I

Marginal 

Reserves

Demonstrated 

Subeconomic 

Resources

Inferred

Inferred 

Reserves

Inferred 

Marginal 

Reserves

Inferred 

Subeconomic 

Resources

UNDISCOVERED RESOURCES

Probability Range

Hypothetical Speculative

Major elements of mineral resource classification, excluding reserve base and inferred reserve base. Modified from 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.

East Fork High Rock Canyon Wilderness Study Area B13
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

pre -Archean 2

EPOCH

Holocene

Pleistocene

Pliocene

Miocene

Oligocene

Eocene

Paleocene

Late 

Early

Late 

Middle 

Early

Late 

Middle 

Early

Late 

Early

Late 

Middle 

Early

Late 

Early

Late 

Middle 

Early

Late 

Middle 

Early

Late 

Middle 

Early

Late 

Middle 

Early

AGE ESTIMATES 

OF BOUNDARIES 

(in Ma)

- 0.010

- 1.7

- 5*J

f\ M

- 24 

 opoo 

- 55*j\j 

cc

- 96 

 100

one

- ~940 £-*+\J

- 290 ^\J\J 

OO/\

 ~330 

 %j\/\j Ifif)

- 410

*too

- 500

_ ,^cTni ~b/U 

_ ann yuu 

- 1600

- 2500

- 3000

- 3400 

ARCH

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

Informal time term without specific rank.

B14 Mineral Resources of Wilderness Study Areas Northwestern Nevada GPO 585-045/78027