~ 

Min.era] urces of t'he Cactu Plain »and 

East Cact s Plain Wild rness Study Areas, 

La Paz County, Arizona 

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Chapter D 

Mineral Resources of the Cactus Plain and 

East Ca~tus Plain Wilderness Study Areas, 

La Paz· County, Arizona 

By RICHARD M. TOSDAL, ROBERT G. EPPINGER, 

JAMES A. ERDMAN, WILLIAM F. HANNA, JAMES A. PITKIN, 

H. RICHARD ·BLANK, JR., RICHARD M. O'LEARY, and . 

JOHN R. WATTERSON 

U.S. Geological Survey 

TERRY J. KREIDLER 

U.S. Bureau of Mines 

U.S. GEOLOGICAL SURVEY BULLETIN 1704 

MINERAL RESOURCES OF WILDERNESS STUDY AREAS: 

HAVASU REGION, ARIZONA 
U.S. DEPARTMENT OF THE INTERIOR 

MANUEL LUJAN, jR., Secretary 

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director 

Any use of trade, product, or firm names 

in this publication is for descriptive purposes only 

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

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1990 

For sale by the 

Books and Open-File Reports Section 

U.S. Geological Survey 

Federal Center, Box 25425 

Denver, CO 80225 

Library of Congress Cataloging-in-Publication Data 

Mineral resources of the Cactus Plain and East Cactus Plain Wilderness Study 

Areas, La Paz County, Arizona/ by Richard Tosdal...[et al.]. 

p. cm.-(Mineral resources of wilderness study areas-Havasu region, 

Arizona : ch. D) (U.S. Geological Survey bulletin ; 1704-D) 

Includes bibliographical references. 

Supt. of Docs. no.: I 19.3:1 704-D 

1. Mines and mineral resources-Arizona--Cactus Plain Wilderness. 

2. Mines and mineral resources-Arizona-East Cactus Plain Wilderness. 

3. Cactus Plain Wilderness (Ariz.) 4. East Cactus Plain Wilderness (Ariz.) I. Tosdal, 

Richard M. II. Series. Ill. Series: U.S. Geological Survey bulletin ; 1704-D. 

QE75.B9 no. 1704-D 557.3 s-dc 20 90-14078 

[TN24.A] [553'.09791 '72] 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 Cactus Plain (AZ-050-

014-NB) and East Cactus Plain (AZ-050-017) Wilderness Study Areas, La Paz County, 

Arizona. 
CONTENTS 

Summary Dl 

Absttact Dl 

Character and setting D 1 

Mineral resource potential and identified resources DJ 

Introduction DJ 

Location and physiography D4 

Previous work D4 

Methods D4 

Acknowledgments D4 

Appraisal of identified resources DS 

Mining activity DS 

Energy resources D6 

Resource appraisal D6 

Conclusions DlO 

Assessment of mineral resource potential DlO 

Geologic setting DlO 

Geochemical studies Dll 

Methods Dl2 

Rock, stream-sediment, and heavy-mineral-concentrate samples DIS 

Creosotebush and paloverde samples D16 

Bacillus cereus D17 

Interpretation D17 

Geophysical studies D18 

Gravity data D20 

Aeromagnetic data D21 

Natural radioelement data D22 

Mineral resource potential D23 

Base and precious metals D23 

Barite and fluorite D23 

Manganese D24 

Uranium D24 

Beryllium D24 

Bentonitic clay D24 

Sand D24 

Oil and gas D24 

References cited D2S 

Appendixes D29 

Definition of levels of mineral resource potential and certainty of 

assessment DJO 

Resource/reserve classification D31 

Geologic time chart D32 

FIGURES 

1. Index map showing location of Cactus Plain and East Cactus Plain Wilderness Study 

Areas, La Paz County, Arizona D2 

2. Map showing mineral resource potential and generalized geology of Cactus Plain 

and East Cactus Plain Wilderness Study Areas, La Paz County, Arizona D8 

3. Geochemically anomalous areas in and near Cactus Plain and East Cactus Plain 

Wilderness Study Areas, La Paz County, Arizona D13 

Contents V 
VI Contents 

4. Bouguer gravity anomaly map of Cactus Plain and East Cactus Plain Wilderness 

Study Areas, La Paz County, Arizona, and surrounding region Dl8 

5. Residual total-intensity aeromagnetic map of the Whipple, Buckskin, and northern 

Plomosa Mountains, Arizona and California Dl9 

6. Aeromagnetic anomaly map of Cactus Plain and East Cactus Plain Wilderness Study 

Areas, La Paz County, Arizona, and surrounding region D20 

7. Aeromagnetic anomaly map of region northwest of lat 34 o N ., long 114 o W. that 

includes part of Cactus Plain Wilderness Study Area, La Paz County, Arizona D21 

TABLES 

1. Summary of production data for mineral districts within ihe mining districts in the 

region surrounding Cactus Plain and East Cactus Plain Wilderness Study 

Areas DS 

2. Geochemical data for samples from Cactus Plain and East Cactus Plain Wilderness 

Study Areas D7 

3. Analytical results for dune-sand samples from Cactus Plain and East Cactus Plain 

Wilderness Study Areas D7 

4. Summary statistics for anomalous concentrations of elements from rock, streamsediment, heavy-mineral-concentrate, creosotebush, and paloverde samples; and for 

Bacillus cereus spore counts from samples collected in and around Cactus Plain and 

East Cactus Plain Wilderness Study Areas Dl4 · 
Mineral Resources of the Cactus Plain and 

East Cactus Plain Wilderness Study Areas, 

La Paz County, Arizona 

By Richard M. Tosdal, Robert G. Eppinger, james A. Erdman, William F. Hanna, James A. Pitkin, 

H. Richard Blank Jr., Richard M. O'Leary, and John R. Watterson 

U.S. Geological Survey 

Terry J. Kreidler 

U.S. Bureau of Mines 

SUMMARY 

Abstract 

The Cactus Plain (AZ~SD-014-NB) and East Cactus Plain 

(AZ-050-017) Wilderness Study Areas are in west-central Arizona, about 4 mi southeast of Parker, Arizona. At the request 

of the U.S. Bureau of Land Management, a mineral survey of 

approximately 79,065 acres was conducted by the U.S. Geological Survey and U.S. Bureau of Mines to appraise their 

identified mineral resources (known) and to assess their mineral 

resource potential (undiscovered). In this report, "study area .. 

refers collectively to both wilderness study areas for which a 

mineral survey was requested by the U.S. Bureau of Land 

Management. 

The southeastern corner of the Cactus Plain Wilderness 

Study Area is within the northern part of the Plomosa mining 

district (Northern Plomosa and Bouse mineral districts). The 

northeastern corner of the East Cactus Plain Wilderness Study 

Area is in the Midway mining district. The Cienega and Santa 

Maria mining districts are within 8 mi and lie north of the 

study area. Gold, silver, copper, and minor amounts of lead, 

zinc, manganese, barite, and fluorite have been produced 

from these districts, though no production is reported from 

mines located within the study area. There are no identified 

metallic resources in the study area. 

The Cactus Plain and East Cactus Plain Wilderness Study 

Areas have high resource potential for gold, silver, copper, 

lead, and zinc. An area in the southeastern part of the Cactus 

Plain Wilderness Study Area has high resource potential for 

barite and fluorite. Another in the northwestern part of Cactus 

Manuscript approved for publication, August 27, 1990. 

Plain Wilderness Study Area has moderate resource potential 

for barite. These same two areas of Cactus Plain Wilderness 

Study Area also have moderate resource potential for manganese as well as low resource potential for uranium and beryllium. The entire study area has low resource potential for 

bentonitic clay. The southern three-quarters of the East Cactus 

Plain Wilderness Study Area and the northern half of the 

Cactus Plain Wilderness Study Area have high resource potential for sand suitable for foundry, fracturing, and abrasive 

uses. The study area has no resource potential for oil and 

gas. 

Character and Setting 

The Cactus Plain (AZ-05()...{)14-A/B) and East Cactus Plain (AZ-05()...{)17) Wilderness Study Areas are approximately 4 mi southeast of Parker, Ariz., and include 

approximately 79,065 acres of a gentle plain partly covered 

by sand dunes (fig. 1). Isolated bedrock knobs protrude 

above the plains and dunes. Elevations within the study 

area rise from about 700 ft above sea level on the west to 

about 1,500 fi on the east The plain is surrounded by 

mountain ranges, including the Buckskin Mountains on the 

north and northeast, the Bouse Hills on the southeast, and 

the Plomosa Mountains on the south. The Colorado River 

lies about 4 mi to the northwest Ephemeral washes drain 

from the study area into Osborne Wash on the north and 

Bouse Wash on the south. The Centtal Arizona Project 

Canal separates Cactus Plain Wilderness Study Area from 

East Cactus Plain Wilderness Study Area. 

The study area lies in the highly extended terrane of 

west-centtal Arizona, immediately west and south of middle 

Tertiary metamorphic core complexes (Rehrig and Reynolds, 

Mineral Resources of the Cactus Plain and East Cactus Plain Wilderness Study Areas, La Paz County, Arizona 01 
1980). Most ranges in this region are fringed by low-angle 

normal faults of regional extent, known as detachment faults, 

that accommodated large-scale extensional deformation in 

the late Oligocene and Miocene (Davis and others, 1980; 

Spencer and Reynolds, 1986, 1989a, 1989b; Davis, 1988) 

(see "Appendixes" for geologic time chart). Detachment 

faults near the study area include the Buckskin-Rawhide 

detachment fault that is exposed discontinuously near the 

WHIPPLE MOUNTAINS 

34° 

Oa APPRO~ATEBOUNDARY 

OF 

CACTUS PLAIN 

WILDERNESS STUDY AREA 

(AZ-050-014-NB) 

8 

AREA OF MAP 

95 

Cactus 

ATCHISON 

-···-···-.. Bouse 

Northern Plomosa 

mineral district 

0 

north and east borders of the study area (fig. 2) and the 

Plomosa detachment fault that crops out in the northern 

Plomosa Mountains along the south border of the Cactus 

Plain Wilderness Study Area. Still farther west, the Moon 

Mountains detachment fault is exposed on the north flank 

of the Moon Mountains (fig. 1) and dips northeastward 

beneath the western part of the Cactus Plain Wilderness 

Study Area. 

Plain 

10MILES 

APPROXIMATE BOUNDARY 

OF 

EAST CACTUS PLAIN 

iWILDERNESS STUDY AREA 

(AZ-050-017} 

Figure 1. Index map showing location of Cactus Plain and East Cactus Plain Wilderness Study Areas, La Paz County, Arizona. 

Also shown are approximate boundaries of mining districts (dashed lines) as defined by Keith (1978) and their subdivision into 

mineral districts and subdistricts (patterned areas) by Keith and others (1983a, b) and Spencer and Welty (1989). 

02 Mineral Resources of the Wilderness Study Areas: Havasu Region, Arizona 
Detachment faults divide the bedrock geology of the 

adjoining mountain ranges into two parts; these are an extended upper plate of Proterozoic, Paleozoic, Mesozoic, and 

Tertiary metamorphic, igneous, and sedimentary rocks and 

a lower plate of Proterozoic, Paleozoic, Mesozoic, and Tertiary metamorphic and igneous rocks. Sedimentation and 

volcanism accompanied extension, and these syntectonic 

rocks now crop out in the highly faulted upper plate (Davis 

and others, 1980; Spencer and Reynolds, 1989b ). Extensional deformation was followed by basaltic volcanism and 

locally silicic volcanism in the Miocene (Davis and others, 

1980; Suneson and Lucchitta, 1983; Grubensky, 1989). 

Conglomerate and sandstone are interbedded with and overlie 

the basaltic rocks. In the late Miocene and continuing into 

the Pliocene and perhaps the Pleistocene, the low areas 

were flooded by marine waters in which the sedimentary 

strata of the Bouse Formation were deposited (Metzger, 

1968; Buising, 1987). The Bouse Fonnation, the dominant 

rock unit at the surface in the study area, overlies unconfonnably the rocks that underwent extensional deformation 

in the middle Tertiary. 

Detachment faults, associated syntectonic basins, and 

younger high angle faults are important controls on the distribution of mineral resources in the region (Welty and others, 1985; Spencer and Welty, 1986, 1989). Mineral exploration in western Arizona and southeastern California has 

demonstrated the association of these rocks and geologic 

structures to various types of deposits (Sherbourne and others, 1979; ·Wilkins and Heidrick, 1982; Wilkins and others, 

1986; Spencer and others, 1988; Wilkinson and others, 1988; 

Lehman and Spencer, 1989). In the Cactus Plain and East 

Cactus Plain Wilderness Study Areas, the Miocene basalt, 

the Bouse Fonnation, and the Quaternary eolian and alluvial 

deposits unconformably overlie the highly extended terrane 

and effectively conceal any metallic deposits that may be 

present 

Mineral Resource Potential and Identified 

Resources 

Most of the mineral deposits in the region of the Cactus Plain and East Cactus Plain Wilderness Study Areas are 

located within the intensely faulted rocks that lie in the 

upper plates of detachment faults (Spencer and Welty, 1989). 

Less common metallic deposits are found in the mylonitic 

rock of the lower plate close·to the detachment fault (Spencer and Welty, 1989). Upper and lower plate rocks are 

buried beneath the unconfonnably overlying late Tertiary 

sedimentary and volcanic rocks in the study area. This 

extensive cover hinders the assessment of mineral resource 

potential of the study area. Despite this limitation, the projection of structures and rock types into the study area, the 

knowledge of the location of deposits in the region, past 

mining activity, and the geochemical and geophysical data 

gathered during this study allow for a mineral resource assessment of the study area. This assessment does not indicate that deposits are actually present or that they are sufficiently near the surface to be accessible. Only with additional work can actual deposits be located. 

Geochemical and geophysical data from the study 

areas indicate that three areas have high resource potential 

with a high degree of certainty for gold, silver, copper, 

lead, and zinc, whereas the remainder of the study area has 

high resource potential with a lower degree of certainty for 

these elements. The three specific areas lie along the northeast border of the East Cactus Plain Wilderness Study Area 

and in the northwestern part and southeastern part of the 

Cactus Plain Wilderness Study Area. An area in the southeastern part of Cactus Plain Wilderness Study Area has 

high resource potential for barite and fluorite, and another 

area in the northwestern part of Cactus Plain Wilderness 

Study Area has moderate resource potential for barite; these 

two areas also have moderate resource potential for manganese and low resource potential for uranium and beryllium. 

The entire study area has low resource potential for bentonitic clay. The southern three-quarters of the East Cactus 

Plain Wilderness Study Area and the northern half of the 

Cactus Plain Wilderness Study Area have high resource 

potential for sand suitable for foundry, fracturing, and abrasive uses. The entire study area has no resource potential 

for oil and gas. · No identified resources are present in the 

study area. 

INTRODUCTION 

This mineral survey was requested by the U.S. Bureau 

of Land Management and is the result of a cooperative effort 

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

An introduction to the wilderness review process, mineral 

survey methods, and agency responsibilities was provided 

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

evaluates identified resources at individual mines and known 

mineralized areas by collecting data on current and past 

mining activities and through field examination of mines, 

prospects, claims, and mineralized areas. Identified resources 

are classified according to a system that is a modification of 

that described by McKelvey (1972) and U.S. Bureau of 

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

Survey studies are designed to provide a scientific basis for 

assessing the potential for undiscovered mineral resources 

by detennining geologic units and structures, possible environments of mineral deposition, presence of geochemical and 

geophysical anomalies, and applicable ore-deposit models. 

Goudarzi ( 1984) discussed mineral assessment methodology 

and tenninology as they apply to these surveys. Definition 

of levels of mineral resource potential and certainty of assessment and the resource/reserve classification are included 

in the "Appendixes." 

Mineral Resources of the Cactus Plain and East Cactus Plain Wilderness Study Areas, La Paz County, Arizona 03 
Location and Physiography 

The Cactus Plain (AZ-050--014-A/B) and East Cactus Plain (~50--017) Wilderness Study Areas are approximately 4 mi southeast of Parker, Ariz., and include 

approximately 79,065 acres on a gentle plain. Isolated bedrock knobs protrude above the plain. Elevations within the 

study areas rise from about 700 ft above sea level on the 

west to about 1,500 ft on the east. The plain is surrounded 

by mountain ranges, including the Buckskin Mountains on 

the north and northeast, Bouse Hills on the southeast, and 

Plomosa Mountains on the south. The Colorado River lies 

some 4 mi to the northwest (fig. 1). Ephememl washes 

drain from the study area into Osborne Wash on the north 

border and Bouse Wash on the south border. The Central 

Arizona Project Canal separates Cactus Plain Wilderness 

Study Area on the west from East Cactus Plain Wilderness 

Study Area on the east 

Access to the Cactus Plain Wilderness Study Area is 

from Arizona Highway 72 on the south, a poorly maintained sand road that parallels a powerline along the west 

border, a paved road along Osborne Wash on the north, the 

service road for the Central Arizona Project Canal along 

the northeast, and from maintained dirt roads between Bouse 

and Swansea along the southeast border of the study area 

(fig. 1 ). The Atchison, Topeka, and Santa Fe Railroad 

borders the Cactus Plain Wilderness Study Area on the south. 

Access to the East Cactus Plain Wilderness Study Area is 

also from the service road for the Central Arizona Project 

Canal along the southwest, from maintained dirt roads between Bouse and Swansea on the southeast and between 

the Osborne Wash road and Swansea on the north, and by a 

service road to a powerline along the northeast border 

(fig. 1). 

Previous Work 

Early descriptions of the rock types and various mineral deposits in the region are found in Lee (1908), Bancroft 

(1911), and Jones and Ransome (1920). Jemmet (1966) 

mapped the northern Plomosa Mountains. Fernandez (1965) 

and Zambrano (1965) studied mines in the Buckskin Mountains immediately north of the study area. Geologists from 

the Arizona Geological Survey have studied the geology 

and setting of the mineral occurrences in the region (Keith, 

1978; Scarborough and Wilt, 1979; Keith and others, 1983a, 

b; Welty and others, 1985; Spencer and Welty, 1986, 1989; 

Spencer and Reynolds, 1989a; Grubensky, 1989) and their 

work has been invaluable for this study. Field studies of 

extensional deformation in the Whipple Mountains and parts 

of the Buckskin Mountains are also important sources of 

information (Davis and others, 1980; Frost, 1981, 1983; 

Marshak and VanderMeulen, 1989). The Bouse Formation 

was ftrst studied by Metzger (1968) as part of a hydrologic 

study of the Colomdo River area (Metzger and others, 1973). 

Buising (1987) defined the stratigraphy and paleoenvironment of the Bouse Formation in more detail. 

Keith (1978), Keith and others (1983a, b), and Spencer and Welty (1989) defined the mining and mineral districts throughout the region and their nomenclature is used 

herein. Areas outside the study area have been explored for 

precious metal and uranium-vanadium deposits (Sherbourne 

and others, 1979; Wilkins and Heidrick, 1982; Wilkins and 

others, 1986; Spencer and others, 1988; Lehman and Spencer, 1989) and the results of this work are applicable to the 

mineral resource potential of the study area. 

Methods 

The U.S. Geological Survey conducted detailed field 

investigations of the Cactus Plain and East Cactus Plain 

Wilderness Study Areas in 1986 and 1988. This work included geologic mapping at scales of 1:24,000, geochemical sampling, and the examination of outcrops for evidence 

of mineralization. The geochemical survey, conducted between September 21 and 27, 1988, included collection of 

rocks and stream sediments from areas of bedrock older 

than the Bouse Formation and Quaternary eolian deposits, 

the sedimentary rocks and deposits that cover m.uch of the 

study area. Biogeochemical sampling in areas of the younger 

sedimentary rock and deposits was necessary for assessing 

the possibility of buried metallic deposits beneath these units. 

Available regional gravity, aeromagnetic, and aerial gammaray spectrometry surveys were also used in the assessment 

U.S. Bmeau of Mines personnel obtained minerals 

information from published and unpublished literature, U.S. 

Bureau of Mines files, and mining claim and oil and gas 

lease records at the U.S. Bureau of Land Management State 

Office in Phoenix. Fieldwork consisted of a search for 

mines and prospects and the examining and sampling rock 

outcrops and unpatented mining claims in and near the study 

area. 

Acknowledgments 

This work was supported by the National Mineral 

Resource Assessment Program of the U.S. Geological 

Survey. Discussions with the J .E. Spencer and SJ. Reynolds 

of the Arizona Geological Survey improved our understanding of the geology of the area. J .E. Spencer kindly provided 

his geologic mapping of the Buckskin Mountains for use in 

this report. Special thanks are extended to Tom Peacock 

for preparation of plant samples for geochemical analysis 

and to Diana Mangan for preparation of the figures. 

04 Mineral Resources of the Wilderness Study Areas: Havasu Region, Arizona 
APPRAISAL OF IDENTIFIED RESOURCES 

By Terry J. Kreidler 

U.S. Bureau of Mines 

U.S. Bureau of Mines personnel reviewed sources of 

minerals information, including published and unpublished 

literature, U.S. Bureau of Mines files, and mining claim 

and oil and gas lease records at the U.S. Bureau of Land 

Management State Office in Phoenix. Discussions on the 

mineral resources of the study areas were held with U.S. 

Bureau of Land Management personnel at the District Office in Yuma and the resource area office in Lake Havasu 

City, Ariz. 

Fieldwork, completed in 16 employee-days, consisted 

of examining and sampling rock outcrops and unpatented 

mining claims in and near the study area. Thirteen samples 

were taken: eight rocks, two stream sediment, one panned 

concenttate, and two dune sand. Six samples were analyzed for gold and silver by frre assay and six by inductively 

coupled plasma-atomic emission spectroscopy for copper, 

lead, zinc, barium, and arsenic. The dune-sand samples 

were analyzed for silica and other elements that affect the 

\ 

suitability for glass manufacture and other industrial uses. 

Kreidler (1986, 1987) presents more detail on most aspects 

of this study. Complete analytical data are available for 

inspection at the U.S. Bureau of Mines, Intermountain Field 

Operations Center, Building 20, Denver Federal Center, 

Denver, CO 80225. 

Mining Activity 

The Cactus Plain and· East Cactus Plain Wilderness 

Study Areas are surrounded by four mining districts (table 

1, fig. 1). The northeastern comer of the East Cactus Plain 

Wilderness Study Area is in the Midway mining district. 

This district contains gold, silver, and copper in spotty deposits along faults and fractures in mylonitic gneiss, schist, 

marble, and calc-silicate rocks of Proterozoic and Mesozoic 

protolith age. The Cienega mining district (7 .5 mi north of 

Cactus Plain Wilderness Study Area) produced gold, silver, 

copper, and minor amounts of lead from ore occurring as 

replacement deposits in weakly metamorphosed Paleozoic 

and Mesozoic limestone, shale, and quartzites, which structurally underlie Proterozoic gneiss in places. The Santa 

Table 1. Summary of production data for mineral districts within the mining districts in the region surrounding 

Cactus Plain and East Cactus Plain Wilderness Study Areas, La Paz County, Arizona 

[Data from Keith (1978), Keith and others (1983b), and Spencer and Welty (1989). Gold and silver given in troy ounces, copper, lead, and 

zinc given in short tons of ore. Mn, manganese;-, not applicable] 

Mineral When Production data 

district active Gold Silver Copper lead Zinc Other 

Clenega mining dlstrld 

Cienega ..... 1880-1969 12,011 1.596 857 

Mammon ... 1880-1969 60 142 42.5 

Pride .......... 1911-1912 100 4,000 0.01 

Midway mining district 

Midway ..... Early 1900's 45 35 4.7 

to present. 

Plomosa mining dlstrld 

Plomosa .... Intermittently 25,000 129,200 526 344 65 

since 1860's. 

Bouse ........ 1928-1930 100 6.5 9,000 tons 

Mn; 2,700 tons 

barite. 

Santa Marla mining district 

Clara. ......... Intermittently 35 1,738 2,335 

early 1900-1955. 

Planet ........ Intermittently 317 268 9,752 

since 1860's. 

Swansea .... Intermittently 507 33,112 13,200 400 tons 

since 1860's. Mnore. 

Mineral Resources of the Cactus Plain and East Cactus Plain Wilderness Study Areas, La Paz County, Arizona OS 
Maria mining district (5 mi north of East Cactus Plain Wilderness Study Area) produced gold, silver, and copper from 

ore in massive to lensing iron-oxide replacement bodies in 

Paleozoic and Mesozoic metasedimentary rocks. The Plomosa mining district includes the Black Mountain mine, 

which lies adjacent to the southern part of Cactus Plain 

Wilderness Study Area, and base- and precious-metal mines 

in the northern Plomosa Mountains, a few miles south. The 

district produced gold, silver, copper, lead, .zinc, manganese, and barite from veins and irregular bodies in Paleozoic and Mesozoic sedimentary rocks and Tertiary volcanic 

and sedimentary rocks. As of June 1990, mines within 4 to 

5 mi of the study area were inactive. However, the Copperstone mine, some 10 mi southwest of Cactus Plain Wilderness Study Area, is active and is one of the largest producing gold mines in Arizona (Spencer and others, 1988). 

A mining district is delineated on the basis of mineral 

occurrence locations and most production records and early 

literature use these districts as a means of categorizing information. Keith and others (1983b) arranged the mineral 

occurrences of Arizona into mineral districts on the basis of 

geologic criteria of metallogenic systems of similar age and 

style of mineralization. A single mining district may contain more than one mineral district. The Cienega mining 

district, for example, includes the Cienega, Mammon, and 

· Pride mineral districts; the Santa Maria mining district includes the Clara, Planet, and Swansea mineral districts; the 

Plomosa mining district includes the Northern Plomosa and 

Bouse mineral districts; the Midway mining district includes 

the Green Streak subdistrict of the Midway mineral district. 

See figure 1 for location of mining and mineral districts. 

Mining claims have been located near the study area 

in the Cienega, Midway, and Plomosa mining districts, and 

at least eight claims have been staked on Black Peak, 1 mi 

northwest of Cactus Plain Wilderness Study Area. U.S. 

Bureau of Land Management claim records list 15 

unpatented claims that are in the Cactus Plain Wilderness 

Study Area. As of September 1987, no claims were located 

in the East Cactus Plain Wilderness Study Area. No visible 

evidence of any recent mining activity was found on any of 

the claims. 

Energy Resources 

About 50,000 acres of the study area are covered by 

oil and gas leases. Ryder (1983, p. C19), however, rates 

the oil and gas resource potential of the study areas as low 

because the organic richness, reservoir quality, and thermal 

history of the rocks are not conducive to the formation of 

significant volumes of hydrocarbons. The leasing is probably a result of speculation that the hydrocarbon-rich overthrust belt, which produces large quantities of oil and gas in 

Wyoming, extends southward into Arizona (Keith, 1979, p. 

10). To date, all exploratory drilling in Arizona testing this 

theory has had negative results (Reif and Robinson, 1981). 

As of September 1986, the leases in the study area had not 

been drilled ot tested, but in 1985, Petty-Ray Geophysical 

Co. ran a seismic line a. few miles north and east of the 

area; the results of the survey are proprietary. 

Resource Appraisal 

No metallic mineral resources were identified in the 

study area. The middle Tertiary and older rocks that crop 

out in the study area are only sparsely mineralized. Samples 

taken in and near the study area contain insignificant amounts 

of gol~ silver, copper, lead, and zinc, except for one sample, 

which is from Tertiary sandstone and conglomerate on the 

flank of Black Peak outside the northwest corner of the 

Cactus Plain Wilderness Study Area. This sample (table 2, 

sample 1) contains concentrations of lead and zinc several 

times the background level. 

At the Green Streak mine, about 1 mi northeast of the 

East Cactus Plain Wilderness Study Area (fig. 2), oxidized 

copper minerals occur locally in a quartz vein, trending N. 

35" W. and dipping 55" NE., in gneiss and schist in the lower 

plate of the Buckskin-Rawhide detachment fault. Workings consist of two shafts, about 35 ft and 100ft deep, an 

adit, and several prospect pits and trenches; the mine accounts for nearly all the recorded production from the Midway district Samples from the mine area contain 0.74 to 

greater than 2 weight percent (or 7,443 to greater than 20,000 

parts per million, ppm) copper and 0.4 to 1.87 ppm gold, 

and anomalous concentrations of silver (table 2). Because 

of the spotty, discontinuous nature of the mineralized rock, 

no base- or precious-metal resource was identified. Barium 

concentrations in the three mine samples are 0.15 to greater 

than 3 weight percent or 1,500 to greater than 30,000 ppm 

(table 2) higher than the average of 425 ppm (0.043 weight 

percent) for metamorphic rocks (Levinson, 1980, p. 865). 

No barite, a barium mineral, was identified. 

In the Cactus Plain Wilderness Study Area, barium 

and arsenic values in the three basalt and two sandstone 

samples are higher than average for their respective rock 

types. Sample values (table 2) ranged from 1,200 to 8,000 

ppm barium and 30 to 50 ppm arsenic (the 130 ppm value 

for sample 7 is suspect). Average contents for similar rock 

types are: barium, 250 ppm for basalt and 10 to 100 ppm 

for sandstone; arsenic, 2 ppm for basalt and 1 ppm for 

sandstone (Levinson, 1980, p. 864-865). 

Barium is highly mobile in mineralizing systems and 

is commonly associated with lead-zinc-silver deposits; its 

distribution often extends several miles from a deposit 

(Levinson, 1980, p. 865). In the northern part of the Plomosa mining district, barite is a common by-product in the 

silver-copper-lead-zinc ores and is found with fluorite in 

volcanic agglomerate at the Black Mountain mine adjacent 

to the southeastern part of the Cactus Plain Wilderness Study 

06 Mineral Resources of the Wilderness Study Areas: Havasu Region, Arizona 
Table 2. Geochemical data for samples from Cactus Plain and East Cactus Plain Wilderness Study Areas, La Paz County, 

Arizona 

[Gold and silver determined by fire assay, all other elements by inductively coupled plasma-atomic emission spectroscopy. -, not detected; na, not 

analyzed; <,less than given value; ppm, parts per million; ppb, parts per billion. Complete analytical tables and location of samples are available in 

Kreidler (1986, 1987)] 

Sample Au Ag Cu Pb Zn 8a As 

no. (ppbJ {ppm) Description 

Stream-sediment and roek samples 

na na 30 400 500 3,700 50 Iron-stained sandstone and 

conglomerate; collected 

on flank of Black Peak. 

3 na na 7.9 32 180 8,000 30 Iron-stained sandstone 

and conglomerate. 

4 3,500 na na na na na Material from wash 

draining east side of 

Black Peak. 

6 na na 41 <10 120 3,700 32 Scoriaceous basalt. 

capped by limestone. 

7 na na 21 27 31 6,200 130. Do. 

8 na na 6.9 <10 170 1,200 30 Do. 

Green Streak mine 

1 608 1,500 7,443 7 72 

2 400 6.400 >20,000 9 78 

3 1,870 600 15,392 56 107 

Area (fig. 2). Thus, the barium enrichment described previously could be an alteration halo related to the mineralization that took place in the Plomosa mining district No 

evidence of a barite deposit was found in the study area. 

Arsenic is also associated with deposits of gold, silver, copper, and zinc (Levinson, 1980, p. 864-865), all of 

which have been produced from · the nearby mining districts, particularly the Plomosa mining district As with 

barium, arsenic enrichment is probably an alteration halo 

surrounding the deposits in the northern Plomosa Mountains and possibly those in the other districts as well.· 

The barium and arsenic alteration patterns could also 

indicate that base- and precious-metal deposits are concealed 

beneath the Bouse Formation in the study area. Extensive 

and costly subsurface exploration would be necessary to 

test this conjecture. 

Analyses of two dune-sand samples from the study 

area showed it to be unsuitable for use in glass production 

because of low silica (Si02

) and high iron (Fe 0~, chromium (Cr), and aluminum (~0:) content (table 3). The 

sand is, however, suitable for use as foundry, fracturing, 

and abrasive sand according to criteria described by Bates 

1.500 select 

>30,000 3 chip 

25,500 4 select 

Table 3. Analytical results for the dune-sand samples from 

Cactus Plain (CP) and East Cactus Plain (ECP) Wilderness 

Study Areas, La Paz County, Arizona 

[See figure 3 for definition of element symbols and text for definition of 

chemical compounds. All detenninations by inductively coupled plasmaatomic emission spectroscopy. See Kreidler (1986, 1987) for analytical 

descriptions and location of samples] 

Sample 

type 

Si02 Al20l Fe20l Cr Co Ti 

percent parts per million 

CP 90.2 4.5 1.6 180 

ECP 88.7 4.6 1.3 <50 

Average 98.5 0.1 .02 6 

glass sand1 

1

Fran Coope and Harben, 1977, p. 16. 

9.1 

<10 

<2 

1,200 

1,700 

150 

(1960, p. 99-103). Sand is a high-volume, low-unit-value 

commodity and transportation costs are a major factor in its 

economic development. Without a local market, the sand is 

not likely to be developed. 

Mineral Resources of the Cactus Plain and East Cactus Plain Wilderness Study Areas, La Paz County, Arizona 07 
m Area having high mineral resource potential (H) Ag Co~:ties D Area having high mineral resource potential (H) for sand Au Gold 

17'""71 

~ . Ba Barite Area having moderate mineral resource potential (M) BC Bentonitic clay 

D Be Beryllium Area having low mineral resource potential (L) Cu Copper 

F Fluorite 

Mn Manganese 

U Uranium 

Pb Lead 

S Sand 

Zn Zinc 

Levels of certainty of assessment Mines and prospects-See text for discussion 

B Data only suggest level of potential 1 Green Streak mine 4 New Standard mine ' 

C Data give good indication of level of potential 

D Data clearly define level of potential 2 Black Mountain mine 5 Little Golden prospect 

3 Pridemine 

Continued on next page 

08 Figure 2. Mineral resource potential and generalized geology (mapped by R.M. Tosdal, 1986) of Cactus Plain and East Cactus 

(1989), and Marshak and others (1987). Geology of Plomosa Mountains modified from Jemmet (1966). Base from U.S. Geological 
Plain Wilderness Study Areas. Geology of Buckskin Mountains modified from j.E. Spencer (unpub. data, 1987), Grubensky 

Survey, 1:62,500, Black Peak, 1959; Bouse, Utting, 1962; Swansea, 1966. Contour intervals, 20, 40, and 80ft. 

09 
EXPLANATION-Continued 

Geologic map units 

Qal Alluvium (Quaternary}-Unconsolidated deposits of sand, silt, and 

gravel in washes and on piedmonts to the west and east of the 

Plomosa Mountains 

Qs Sand and gravel (Quaternary}-Unconsolidated deposits of sand, 

gravel, and silt in washes 

Ot Talus deposits (Quaternary}-Unconsolidated to semiconsolidated 

talus deposits composed of locally derived gravel and sand; found 

primarily around Black Peak 

Qg Lag gravel (Quaternary}-Unconsolidated pebble to cobble gravel 

lag deposits on wash terraces in western parts of Cactus Plain. 

Clasts consist largely of mylonite and gneiss from the Buckskin 

Mountains 

Qe Eolian sand (Quaternary)-Fine-grained sand forming partly 

stabilized dunes 

QTc Conglomerate and sandstone (Quaternary and Tertiary?}-

Semiconsolidated conglomerate, fanglomerate, sandstone, and 

siltstone veneers on piedmonts, talus, and fan deposits at edges 

of bedrock exposures and older deposits 

Tbo Bouse Formation (Pliocene and Miocene }-Sandstone, siltstone, 

limestone, conglomerate, tuffaceous sandstone, and rare deposits 

of tufa. On west part of Cactus Plain, unit is covered by a thin 

veneer of eolian sand (Qe) and lag gravel (Qg) 

Tba Basalt and agglomerate (Miocene )-Olivine basalt and plagioclase 

megaporphyritic basalt flows, agglomerate, and cinders. 

Unconformably overlain by the Bouse Formation (Tbo). 

Present only in the middle of Cactus Plain; its relationship to 

other volcanic units in adjoining ranges is unknown. Forms 

morphologically distinct cinder cones 

Tt Trachyte and rhyolite tuffs (Miocene)-Interbedded trachytic lava 

flows, lithic-lapilli rhyolitic tuff, hypabyssal intrusions, and 

basalt flows (Grubensky, 1989) 

Tb Basalt (Miocene)-Dark-gray and black basalt flows and minor 

dikes. Rocks are gently tilted to subhorizontal and 

unconformably overlie steeply tilted strata 

Tc Carbonate rocks (Tertiary)-Massive medium- to dark-brown 

ferroan carbonate rocks in replacement deposits in Proterozoic 

and Paleozoic rocks along detachment faults 

Tvs Sedimentary and volcanic rocks (Miocene and (or) Oligocene}-

lnterbedded sandstone, conglomerate, breccia, mudstone, 

limestone, and tuffaceous rocks. Locally contains beds of dark 

andesitic lava flows 

Mzs Metasedimentary and volcanic rocks (Mesozoic }-Quartzite, 

calcareous quartzite, phyllite, and quartz blastophenocrystic 

schist 

Pzq Quartzite and marble (Paleozoic)-Tan and greenish quartzite and 

minor amounts of micaceous quartzite, bluish-gray marble, and 

orange-brown dolomitic marble 

E?Q Granite (Proterozoic)-Medium- to coarse-grained porphyritic 

granite 

gm Granite and metamorphic rocks (Tertiary, Mesozoic, and 

Proterozoic}-Leucocratic hornblende-bearing biotite granite and 

granodiorite, medium- to coarse-grained leucogranite gneiss, 

amphibolite, and locally abundant northwest-trending mafic and 

silicic dikes 

g g Gneiss (Tertiary, Mesozoic, and Proterozoic )-Predominantly 

layered mafic and quartzofeldspathic gneiss and pegmatite. Most 

of the gneiss has plutonic protoliths of several ages. Unit may 

also include some unmapped metasedimentary rocks (Mzs, Pzq). 

Gneissosity locally overprinted by subhorizontal mylonitic 

fabrics. Present in the lower plate of the Buckskin-Rawhide 

detachment fault 

Contact 

-.--·· Fault-Steeply to moderately dipping; dashed where approximately 

located; dotted where concealed; bar and ball on downthrown side 

-ll-IJ.. ... Detachment fault-Low-angle normal fault; dotted where concealed. 

Ticks on upper plate 

Figure 2. Explanation continued. 

010 

Conclusions 

Neither the Cactus Plain nor the East Cactus Plain 

Wilderness Study Area contains known or identified metallic mineral resources. Rocks in the study area contain 

anomalous concentrations of barium and, to a lesser extent, 

arsenic. Barite has been mined just south of the study area 

and is an acceSsory mineral in ores from the Plomosa mining district, but no evidence for a barite deposit was found 

in the study area. Arsenic, as well as barium, can be used 

as a pathfmder element for deposits of gold, silver, copper, 

and zinc, all of which occur north and south of the study 

area and may underlie the eolian deposits and the subjacent 

Bouse Formation, but the requisite subsurface data are lack-. 

ing. The sand is usable in foundry, fracturing, and abrasive 

purposes, but this high-volume, low-unit-value commodity 

can not be shipped any distance profitably. 

ASSESSMENT OF MINERAL RESOURCE 

POTENTIAL 

By Richard M. Tosdal, Robert G. Eppinger, james A. 

Erdman, William F. Hanna, James A. Pitkin, H. Richard 

Blank, Jr., Richard M. O'Leary, and John R. Watterson 

U.S. Geological Survey 

Geologic Setting 

The Cactus Plain and East Cactus Plain Wilderness 

Study Areas lie in the highly extended terrane of westcentral Arizona immediately west and south of middle Tertiary metamorphic core complexes (Rehrig and Reynolds, 

1980). Most ranges in this region are fringed along the 

range-basin interface by low-angle normal faults of regional 

extent, known as detachment faults, that accommodated 

large-scale extensional deformation in the late Oligocene 

and Miocene (Davis and others, 1980; Spencer and Reynolds, 

1986, 1989b, c; Davis, 1988). Detachment faults near the 

study area include the Buckskin-Rawhide detachment fault 

exposed discontinuously near the north and east borders of 

the study area (fig. 2) and the Plomosa detachment fault in 

the northern Plomosa Mountains near the south border of 

the Cactus Plain Wilderness Study Area. Still farther west 

is the Moon Mountains detachment fault that projects underneath the western part of the Cactus Plain Wilderness 

Study Area. 

Detachment faults divide the bedrock geology of the 

adjoining mountain ranges into two parts: an extended upper plate of Proterozoic, Paleozoic, Mesozoic, and Tertiary 

metamorphic, igneous, and sedimentary rocks and a lower 

plate of Proterozoic, Paleozoic, Mesozoic, and Tertiary 

metamorphic and igneous rocks. Extensional deformation 

resulted in a penetrative subhorizontal mylonitic fabric in 
the lower plate rocks in the Buckskin Mountains. Sedimentation and volcanism accompanied extension, and these 

syntectonic rocks unconformably overlie Mesozoic and older 

rocks in the highly faulted upper plate (Spencer and 

Reynolds, 1989c). The middle Tertiary volcanic and sedimentary rocks usually consist of fanglomerate, sandstone, 

local lacustrine limestone, andesitic volcanic flows and agglomerates, and silicic ash flows. Monomictic and 

polymictic breccias and conglomerates are locally interbedded with volcanic and sedimentary rocks and these are likely 

fault-scarp deposits along normal faults above the detachment fault. 

This extended terrane is present above the alluviated 

basins as a series of northeast-trending antiformal and synformal culminations that plunge beneath the alluvial cover 

in the study area (Spencer and Reynolds, 1989b ). Lower 

plate mylonitic rocks form the antiforms and faulted upper 

plate rocks occupy the synforms. Most of the metallic 

mineral deposits in the Buckskin Mountains are found in 

the synforms (Spencer and Welty, 1989). 

Outcrops of bedrock affected by extensional deformation are sparse within the study area. In the northwestern part of the Cactus Plain Wilderness Study Area, several 

knobs above the surrounding younger sedimentary rocks 

consist of Paleozoic marble and micaceous quartzite that 

are faulted against Tertiary megabreccia. This fault contains specularite and carbonate cement The knobs along 

the south border of the Cactus Plain Wilderness Study Area 

are Miocene limestone, sandstone, andesite, and megabreccia and Paleozoic marble that represent the highly faulted 

upper plate of the Plomosa detachment faulL Mylonitic 

gneiss of the lower plate crops out along the northeast border 

of East Cactus Plain Wilderness Study Area. 

Extensional deformation in the region was followed 

by basaltic volcanism and local silicic volcanism in the 

Miocene (Suneson and Lucchitta, 1979, 1983, Grubensky, 

1989). Conglomerate and sandstone deposited in alluvial 

fan environments are interbedded with the volcanic rocks. 

These rocks are referred to as the Osborne Wash Formation 

of Davis and others (1980) and as mesa-forming basalts by 

Suneson and Lucchitta (1983). In the western Buckskin 

Mountains north of the Cactus Plain Wilderness Study Area, 

the postdetachment volcanic and sedimentary rocks are more 

than 600 ft thick, dip slightly southwest, and are cut by 

northwest-trending high-angle faults (Davis and others, 1980; 

Grubensky, 1989; Spencer, 1989). 

Basalt crops out locally in the central part of the Cactus Plain Wilderness Study Area where it is present in two 

forms: fine-grained flows that form linear ridges, and 

megaporphyritic lavas, cinders, and agglomerates that make 

up morphologically distinct cinder cones above the surrounding and onlapping sedimentary rocks of the Bouse 

Formation. The fine-grained basalts probably are correlative with the gently tilted Miocene basalts on the prominent 

mesas north of the Cactus Plain Wilderness Study Area, 

where they have been included in the Osborne Wash Formation of Davis and others (1980) by Grubensky (1989). 

The megaporphyritic basalts may be broadly correlative with 

late Miocene megacrystic basalts found elsewhere in the 

region (Suneson and Lucchitta, 1979, 1983). , 

In the late Miocene(?) and continuing into the Pliocene and perhaps the Pleistocene, low areas were flooded 

by marine waters in which the sedimentary strata of the 

Bouse Formation were deposited (Metzger, 1968; Buising, 

1987). Fine-grained sandstone, limestone, and siltstones 

make up the Bouse Formation. Conglomerate and coarse 

sandstone facies of the formation are adjacent to bedrock 

and represent talus and fan deposits (Buising, 1987). Calcareous tufa deposits, a distinctive rock type of the Bouse 

Formation (Metzger, 1968), cap most of the bedrock knobs 

in the Cactus Plain Wilderness Study Area. The Bouse 

Formation is the dominant unit at the surface in the study 

area. About 500 ft of the Bouse Formation overlies upper 

Miocene conglomerate in the lower part of a 1,000-ft-deep 

drill hole immediately west of the study area (Metzger, 

1968); post-Bouse Formation sedimentary rock, including 

deposits of the Colorado River, are in the top few hundred 

feet of the drill hole. The Bouse Formation thins to the east 

across the study area toward the southwestern Buckskin 

Mountains. 

During the Pleistocene and the Holocene, the Colorado River drainage formed. Tributary washes were established across the region and eolian deposits developed on 

the broad interfluvial plains. Eolian deposits dominate the 

northern part of the Cactus Plain Wilderness Study Area 

and most of the East Cactus Plain Wilderness Study Area. 

The eolian deposits are probably no more that a few tens of 

feet thick. 

Geochemical Studies 

A reconnaissance geochemical survey of the Cactus 

Plain and East Cactus Plain Wilderness Study Areas was 

conducted in 1988 to locate altered, mineralized, or goochemically anomalous areas but was not designed to find 

individual mineral deposits. Because of the sparse outcrops 

(less than one percent exposure) and extensive alluvial and 

eolian cover in the study area, this geochemical survey consisted of two parts. One part followed the conventional 

geochemical approach that uses stream sediments, heavymineral concentrates, and rock samples. Forty-eight rocks, 

18 stream sediments, and 20 heavy-mineral concentrates 

were collected in outcrops of pre-Bouse Formation rock 

inside the study area. The second part consisted of a biogeochemical reconnaissance survey, which augmented 

the scant data base from the conventional approach by providing information on soluble metals that are available at 

depths of less than 70 ft or that are present in the direction 

from which the ground water flows. Biogeochemical 

Mineral Resources of the Cactus Plain and East Cactus Plain Wilderness Study Areas, La Paz County, Arizona 011 
exploration surveys broadly similar to this one have proven 

successful in exploration for disseminated gold prospects 

beneath basin fill in Nevada and in China in areas wholly 

covered with eolian sands (Lovering and McCarthy, 1978; 

Li and others, 1989). 

For the biogeochemical study, samples of creosotebush 

(Larrea trident ala [OC.] Coville) and two species of palover~e, blue paloverde (Cercidium floridum Benth.) and 

little-leaf, or foothill, paloverde (C. microphyllum [Torr.] 

Rose and Johnston) were collected and analyzed, where 

possible, from 80 sites within and around the study area. 

Creosotebush, a shallow-rooted desert plant, was most useful 

because of its widespread distribution and its effectiveness 

for detecting gold anomalies in areas with as much as 70 ft 

of colluvial cover in desert regions (Busche, 1989). The 

more deeply rooted plants such as paloverde, particularly 

blue paloverde, also absorb metals from ground water and 

accumulate them in various above-ground parts (Chaffee, 

1976, 1977). These plants can indicate local mineralized 

ground in areas where no evidence appears in the overburden (Cohen and others, 1987). In this study, however, metal 

anomalies in creosotebush probably indicate the more local 

mineralized sources than do anomalies in paloverde, because the shallow-rooted creosotebush does not reflect regional ground-water geochemistry ·to the extent that the 

deep-rooted paloverdes do. 

Soil samples also were collected at the 80 vegetation 

sample sites to determine the spore content of the bacterium Bacillus cereus. The discovery of B. cereus spore 

population anomalies and the original study of its ecology 

in mineralized soil are discussed by Watterson and others 

(1986). These initial fmdings were the basis for further 

investigation on the potential use of B. cereus in mineral 

exploration, particularly near gold deposits (Parduhn and 

others, 1986; Parduhn, 1987). 

Methods 

Stream-sediment samples, representing a composite 

of rock and soil exposed in the drainage basin, were colhited from small active alluvial channels draining bedrock 

and were sieved and pulverized for chemical analysis 

(Eppinger, 1990a, b). From each site, additional heavymineral-concentrate samples were collected and separated 

in the laboratory into three fractions using an electromagnet: a magnetic, slightly magnetic, and nonmagnetic fraction. 

Nonmagnetic fractions commonly contain the primary and 

secondary ore minerals, and this fraction was examined for 

mineralogical content by microscopic and X-ray diffraction 

methods. Nonmagnetic and slightly magnetic fractions were 

pulverized for chemical analysis, and the magnetic fraction 

was archived. Rocks were collected from prospects, altered 

zones, and outcrops within the study areas; examined 

microscopically; and then pulverized for chemical analysis 

(Eppinger, 1990a, b). 

Vegetation samples generally were collected from 

shallow arroyos or washes (Eppinger, 1990a, b). For 

creosotebush, branch-tip samples stripped by hand from three 

adjacent shrubs were composited into a single sample at 

each site. These samples were predominantly leaf tissue 

with some admixture of fme twigs. Of the two paloverde 

tree species, neither is as wid~spread as creosotebush. However, at least one of the two paloverde species was sampled 

at most sites. Single paloverde trees were sampled at each 

site, and the samples consisted of branch ends about 8-in. 

long. For the more riparian blue paloverde, leaves and 

stems were combined, but for the more drought tolerant 

little-leaf paloverde, samples consisted almost entirely of 

stem material because the leaves appear only after significant rainfall. Blue paloverde was found at 42 sites and 

little-leaf paloverde was found at 36 sites. Five extra samples 

of creosotebush were collected along mineralized faults and 

shear zon'es, and multiple samples were collected at several 

of the mines and prospects outside the study area. For both 

plant and soil samples for B. cereus assays, duplicate 

samples were collected at 10 sites to assess the site variability; one of the duplicate samples from these sites was later 

split after the sample was milled to estimate analytical precision. 

For B. cereus spore counts, surface soil was sampled 

from a single pit at each site. The top 1.25-in. layer of soil 

was sieved through a 30-mesh screen. The minus-30-mesh 

fraction was later further sieved through a 60-mesh screen 

and the B. cereus count was estimated using the fme fraction. The B. cereus spore determinations were made in U.S. 

Geological Survey laboratories following the method outlined by Watterson (1985). 

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

samples were analyzed for 35 elements by semiquantitative 

emission spectrography (Grimes and Marranzino, 1968)~ In 

addition, stream sediments and rocks were analyzed for arsenic, bismuth, cadmium, antimony, and zinc by the more 

sensitive atomic-absorption and inductively coupled plasmaatomic emission spectroscopy (ICP-AES) methods (Crock 

and others, 1987; Motooka, 1988). Stream-sediment and 

rock samples were analyzed for low-level gold (detection 

limit: 50 parts per billion (ppb) for stream sediments, 2 ppb 

for rocks) by graphite-furnace atomic absorptioq (GFAA) 

methods (Thompson and others, 1968; Meier, 198p). 

Plant samples were washed, milled, ashed; ~id-digested, and the solutions analyzed by three techniques: ICPAES, GFAA, and ICP-AES with an organic extraction by 

diisobutyl ketone (ICP-AES/DIBK). A 100-mg (milligram) 

aliquot of each sample was analyzed by ICP-AES (Crock 

and others, 1987) for 40 elements. A 300-mg aliquot was 

analyzed for silver, arsenic, gold, bismuth cadmium, copper, molybdenum, lead, antimony, and zinc by ICP-AES/ 

DIBK (Motooka, 1988), a more sensitive method for most 

012 Mineral Resources of the Wilderness Study Areas: Havasu Region, Arizona 
Au, Ag 

au, ag 

malachite 

r:::::::l 

~ 

EXPLANATION 

Rock, stream-sediment, or heavy-mineralconcentrate sample collection site 

Vegetation and soil sample collection siteSpecific elements detected in these samples 

are listed in text 

Area containing anomalous concentrations of 

elements shown 1 

Upper and lowercase letters denote elements 

detected in rock samples 

Lowercase letters denote elements detected in 

heavy-mmeral-concentrate samples 

Listed minerals detected in either heavymineral-concentrate or rock samples 

Area containing anomalous levels of copper in 

creosotebush or palo verde samples 

0 

• 

Area containing anomalous levels of barium in 

creosotebush or paloverde samples 

Area containing anomalous levels of 

molybdenum in creosotebush or paloverde 

samples 

Sample site with anomalous levels of gold in 

both creosotebush and paloverde samples 

Sample site with anomalous levels of gold in 

creosotebush samples only 

Area containing anomalous amounts of Bacillus 

cereus spores in soil samples 

Ag, silver; As, arsenic; Au, gold; Ba, Barium; Be, 

beryllium; Bi, bismuth; Cd, cadmium; Co, 

cobalt; Cu, copper; Fe, iron; Mn, manganese; 

Mo, molybdenum; Pb, lead; Sb, antimony; Sn, 

tin; Sr, strontium; Th, thorium; W, tungsten; Zn, 

zinc-Same definitions apply to elements shown 

in lowercase letters 

Figure 3. Geochemically anomalous areas in and near Cactus Plain and East Cactus Plain Wilderness Study Areas, La Paz 

County, Arizona, delineated using data from rock, heavy-mineral-concentrate, and vegetation samples and by Bacillus cereus 

spores detected in soils. Base from U.S. Geological Survey, 1:62,500, Black Peak, 1959; Bouse, Utting, 1962; Swansea, 1966. 

Contour intervals 20, 40, and 80 ft. 

Mineral Resources of the Cactus Plain and East Cactus Plain Wilderness Study Areas, La Paz County, Arizona 013 
Table 4. Surl)mary statistics for anomalous concentrations of elements from rock, stream-sediment, 

heavy-mineral-concentrate, .creosotebush, and paloverde samples; and for Bacillus cereus spore 

counts from samples collected in and around Cactus Plain and East Cactus Plain Wilderness Study 

Areas, La Paz County, Arizona 

[See figure 3 for definition of element symbols. See Eppinger and others (1990a, b) for complete analytical data. 

Lower limits of detennination shown in parentheses. n, number of samples analyzed, N, not detected; L. detected but 

lower than detennination limit; G, greater than upper detennination limit. Analyses by emission spectrography, except 

for elements with "-a" or "-i" suffixes, which are by atomic absorption or inductively coupled plasma-atomic emission 

spectroscopy methods, respectively. Values in parts per million unless noted otherwise; pet, percent; ppb, parts per 

billion] 

Element 

Ag (0.5) 

As-i (1) 

Au-a (2 ppb) 

Ba (20) 

Be (1) 

Bi-i (1) 

Cd-i (0.05) 

Co (10) 

cu (5) 

Fe (.05 pet) 

Mn (10) 

Mo (5) , 

Pb (10) 

Sb-i (1) 

Sr (100) 

Zn-i (0.05) 

Ag (1) 

Au (20) 

Ba(50) 

Be(2) 

Sn (20) 

Th (200) 

Fe (0.1 pet) 

Mo (10) 

Th(200) 

w (50) 

Zn(SOO) 

Au-a(1 ppb) 

Cu-a (0.1) 

Ba-a (2) 

Mo-a(0.3) 

Bi-a (2) 

Au-a(l ppb) 

Cu-a (0.1) 

Ba-a (2) 

Mo-a (0.3) 

Minimum 

N 

N 

N 

100 

N 

N 

N 

N 

L 

0.07 pet 

10 

N 

N 

N 

N 

3.6 

N 

N 

4,000 

N 

L 

N 

10pet 

N 

N 

N 

N 

N 

32 

170 

2.7 

N 

N 

38 

190 

.74 

Maximum 50th Average 

5 

170 

400ppb 

3,000 

7 

49 

12 

500 

10,000 

G 

3,000 

30 

200 

32 

5,000 

1,200 

Percentile crustal 

abundance' 

RCK:ks1 (n = 33) 

N 

7 

N 

500 

L 

N 

.25 

15 

20 

1.5 pet 

300 

N 

15 

L 

200 

55 

0.07 

1.8 

4ppb 

425 

2.8 

0.17 

0.2 

25 

55 

950 

1.5 

13 

0.2 

375 

70 

Threshold Number of samples 

above threshold 

1 

20 

20ppb 

2,000 

5 

10 

10 

300 

300 

20pet 

2,000 

5 

50 

5 

2,000 

200 

6 

11 

4 

6 

3 

4 

2 

1 

6 

2 

6 

9 

3 

3 

3 

6 

Nonmagnetic heavy-mineral concentrates~ (n=8) 

1 

L 

G(lO,OOO) 

3 

70 

500 

6,000 

2 

25 

L 

L 

L 

G(lO,OOO) 

3 

70 

L 

Weakly magnetic heavy-mineral concentrates~ (n = 8) 

30pet 

10 

L 

70 

500 

20pet 

N 

N 

N 

N 

Creosotebush (n = 98) 

6ppb 

490 

1,300 

21 

3.3 

0.1 ppb 

67 

590 

7.2 

<2 

Blue paloverde (n = SS) 

13ppb 

170 

2,000 

6.1 

0.1 ppb 

81 

760 

2.9 

30pct 

L 

L 

L 

L 

<1ppb 

92 

760 

8.4 

<2 

<1 ppb 

98 

800 

2.5 

1 

1 

3 

1 

2 

5 

3 

4 

2 

1 

1 

11 

25 

23 

25 

4 

13 

14 

26 

28 

014 Mineral Resources of the Wilderness Study Areas: Havasu Region, Arizona 
Table 4. Summary statistics for anomalous elements from rock, stream-sediment, heavy-mineral 

concentrate, creosotebush, and paloverde samples; and for Bacillus . cereus spore counts from 

samples collected in and around the Cactus Plain and East Cactus Plain Wilderness Study Areas, La 

Paz County Ari~ona-Continued 

Element Minimum Maximum 50th Average Threshold Number of samples 

Percentile crustal above threshold 

abundanceZ 

Little-leaf paloverde (n = 43) 

Au-a(1 ppb) N 4ppb 0.1 ppb· <1 ppb 10 

Cu-a (0.1) 34 120 73 65 27 

Ba-a (2) 190 1,600 810 1,000 10 

Mo-a (0.3) .39 7.2 1.1 2.0 10 

Bacillus cereus spore counts (n = 98) 

counts/g (10) L 25,000 380 1,100 22 

1 These data are derived from samples collected in areas 1-8 shown in figure 3. Areas 9 and 10 are excluded. 2 Data from Levinson (1980). 

of these ore-related elements. One-gram aliquots were analyzed by a modified GFAA method of Meier (1980) to , 

determine the ultralow concentrations of gold normally found 

in plants. Though for plants the GF AA stated lower limit 

of determination for gold is 1 ppb, further work on a subset 

of these samples suggests that typical background gold concentrations are about 0.1 ppb in the ash. 

·Frequency distribution diagrams (hist.Qgrams) and cumulative frequency plots that show the general distribution 

and range of the data were constructed for selected elements. Boundaries between background and anomalous 

element concentrations were chosen based on the crustal 

abundarices for elements given by Levinson (1980). For 

the plant data, any detectable concentrations of gold, antimony, bismuth, and vanadium are considered anomalous. 

Geochemical anomalies in rock, heavy-mineral-concentrate, creosotebush, and paloverde samples and B. cereus 

spore counts in and around the study area are shown in 

figure 3. Summary statistics and thresholds for anomalous 

elements identified ~ samples from the study area are 

listed in table 4. Rock and heavy-mineral-concentrate data 

from samples collected in nearby mineralized areas, area 9 

in the northern Plomosa Mountains (fig. 3), and from area 

10 in the Pride mineral district (fig. 3) aided in identifying 

suites of anomal9us element concentrations and thresholds 

in metallic deposits in the region but are not included in the 

data summary presented in table 4. No detailed follow-up 

geochemical studies of the anomalies identified in the study 

area have been undertaken. 

Rock, Stream-Sediment, and Heavy-Mineral-Concentrate 

Samples 

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

samples were collected from outcrops in and around the 

study area (fig. 3) (Eppinger, 1990a, b). Anomalous concentrations of elements were found in rock samples and in 

the nonmagnetic and slightly magnetic heavy-mineral-concentrate samples. No anomalous concentrations of elements 

were found in stream-sediment samples. 

Samples of quartz veins cutting lower plate mylonitic 

gneiss collected from dumps near the Green Streak mine in 

area 1 (fig. 3) contain gold concentrations of 220 and 400 

ppb (Eppinger, 1990a, b) and 400 to 1,870 ppb (Kreidler, 

1987). These rocks contain anomalous concentrations of 

silver (1-5 ppm) and copper (1,500-10,000 ppm) and slightly 

anomalous concentrations of arsenic, bismuth, antimony, 

molybdenum, lead, and zinc. 

Six rock samples were collected from three outcrops 

of lower plate mylonitic crystalline rocks in area 2, 1 mi 

south of the Green Streak mine. These rocks contain 

anomalous concentrations of gold (1 sample, 30 ppb), copper (as much as 7,000 ppm), molybdenum, lead, barium, 

and strontium (Eppinger, 1990a, b). Thin quartz veins following shear zones cut the gneiss in this area. Oxidized 

pyrite boxwork and chrysocolla were observed in float of 

vein quartz. Two heavy-mineral-concentrate samples from 

arroyos draining these outcrops contain anomalous concenttations of barium, iron, molybdenum, and tungsten. Barite, specularite, and fluorite are present in the nonmagnetic 

heavy-mineral-concentrate samples. 

No anomalous concentrations of metals were found 

in three rock samples of tufa-capped basalt collected in area 

3 (fig. 3). However, gold Oess than 20 ppb) was detected 

by emission spectrography in one heavy-mineral-concentrate sample collected· from an arroyo draining the north 

side of an unnamed hill where the Osborne V ABM (verticalangle benchmark) is located (Eppinger, 1990a, b). The 

same sample contains anomalous concentrations of silver 

(1 ppm) and slightly anomalous concentrations of tin and 

thorium. No gold was observed in a mineralogical scan of 

Mineral Resources of the Cactus Plain and East Cactus Plain Wilderness Study Areas, La Paz County, Arizona 015 
ilie lhleavy-mfumeml!-oollllcellllttmre §ample. A OOOOllll(!J lhle&vymillllem.R-collllcoo~ ~pRe ooRRec!lOO lfrom oo mroyo dlrnnllllillllg ilie OOllllili si«ile 011' iliis lllm1l'W1Ill00 lhliRR OOllllWllllS ooom~OllllS 

oollllcellllU:mtiolllls o11' Rrollll 9 lliJreC, mollyMellll1Ulllllll, oodl iliorillllm. 

A JJOClk swmplle lfrom ioasWla croppfumg ooa illll me& 4 (fig. 

3) collllmfums ooomalloos coocennarnltliolllls of OOrillllm. Of ttwo 

lhle&vy-mfumemll-collllcellllwre §amplles from me same ~ orrne 

contmJrns ooom~oos collllceJrnU:mtioos of mollylbdleJrnllllm oodl ilie 

omeir oorrnttrulllls ooomallooo oorrncerrnttmtiorrns of lbmillllm oodl iliorillllm. A smallll M]01Ulllll& of sclhleelliire, a ttnmgsrellll-bearirrng millllemll, w~ obsenoo illll olllle llllOJrnmagrrnetic llneavy-mirrnernll-collllcellllttmre swmplle. 

Five ll'OClk SM"nplles were collllocred from smallll isoRaredl 

Ollll~Irops of P~oowic memsedlimerrnmrry ll'OClis fum ~ 5 (fig. 

3). These Iroclis, collllecred ~orrng ill"ollll- oodl moogooese-oJtidle-riclhl f~l1Ulllt mlllles, corrntilin ooomallolllls oorrncerrnttmtioJrns of 

sillveir, msellllic, bismllllili, coballa, mollyMemxm, lleadl, zmc, 

irorrn, and! mMgrunese oodl sllightly ooomallous concenltlrations 

of Read!, lbecylllliillllm, arrndl cadmium (Eppirrngeir, 1990a, b). A 

single he&vy-mmem.li-oollllcentrat.e sample coU.ect.ed from \this 

area cona&Jrns mJ~omallmns corrnceJrnttmtioJrnS of ill"on arrndl sllighally 

anomallous OOllllCeJrnttmtiolllls of iliorillllm. Minern.lls ideJrntifiedl 

.firm me JrnOJrnmagrrnetic lhle&vy-mmeJrall-OOJrnceJrnttat.e smnplle lllllldudle OOriae oodl aommalliiirne. 

Eiglhla Iroclk ~plles were oollllecaedl from basal!& Ollll&-

crops illll me& 6 (fng. 3). Thll"ee samplles, oollllecttedl from 

malachire-swrrnedl, qoortz-~ciae veim Cllllttirrng faullredl basalla, oorrnwrrn dlerecaalblle golldl (6, 10, oodl 20 ppb) (Epp.iJrngeir, 

199Da, b). Two goRdl-~g SIDJnplles aliso conttilrn anomalous conceJrnttatiorrns of usenic oodl copper. Other rode 

samples illll abe mea oonmm Momallooo concentrations of 

marrngaJrnese, banillllm, oodl slliighaly anomaimns corrnceJrntrn.tio~rns 

of moRyMemxm. A single bmae-riclhl, heavy-minemll-cmnceJrntrare sample from ttlhle mea contrins ooomallous coJrncelllltrn.timus of banillllm as wellll ~ sR.ighaly Momallous co~rnceJrnamti.om; of lhecyllllium arrndl tillll. 

Two samples of c~ciae veiJrns weire ooHocttedl from 

birecd.attedl Mdlesitic llOCks illll area 7 (fig. 3). Anomallous 

concenltlrations of mMgarrnese, molybdenum, bismuah, and! 

arseJrnic oodl sRigllually arrnom~ous coJrncentrn.tions of zi~rnc and 

coppell" are pireseJrn& m ilie veins (Eppinger, 1990a, lb). 

Ch!rysocona, m~aclluiae Mdl quartz me also presena in \the 

calcite veiJrns. 

Three samples of oodesitic volcarrnic Irocb were collRecredl Jirrn area 8, wlhlnclhl mdudes ilie Blade Mmmmin mme. 

An \three sru1rnpRes oonmfum sHglhtly ooomalous'concentrations 

of siRveir (as muclhl as 1 ppm) arrndl two of ilie allruree oonmm 

anom~ous corrnceJrnltlratio~rns of msennc, antimoJrny, coppell", 

barium, oodl s&Irorrntium. Barite, calldtte, oodl J11uoritte fom 

part of ilie stteepRy ruwn~rng velins in ttllue mea. 

Sevemll samples, collllocredl in area 9 (fig. 3), providle 

additioJrnall mfomation for . maerpreting ilie dla~ from ilie 

stllldy mea. Nme minemliizedl rocl\c samples from pirospects 

illll granitic MdlfeRsic vokooic rocb oontam gold 000 ppb 

and 1,200 ppb) Mdl sillveir 0 sample, 1 ppm); ooomalous 

coocenn:mtioJrns of mse~rnic, coppell", barium, manganese, and 

sttontillllm; Mdl sllighally arrnomallooo corrnceJrntlrations of molybdleJrnllllm, bismuruhl, lleOO!, mud! zD.n:nc (Eppfumgeir, 1990a, b). All 

sP.Jt lhleavy-mfumemll-collllreJrnltlraae ~plies collocredl RHll area 9 

ooJrnurin anoHMl!olll!s coirncerrnltlrn.ltlio~rns of bmtlRm, sttontium, and 

mmugooese, oodl sevemll ~plies aliso contilin anomalous 

coJrncerrnwtiolllls of wngst.ellll, moRyMenum, aJrsenic, and coppell. Bmre lis abumd!M~ in heavy-mJiJrneir~-concentrate 

samples. Ottl!Tleir mlinernlls mcliudle fluorite, specularite, pyritte, COirlllllllldl\\lllfllll, oodl scllneeRite. 

Samplies oolilecttedl lillll ~ 10 (fig. 3) ruse provide 

P.rrnlfoirmatiollll Jfoir furnttelr]pretirrng nhe ~ from \the study area. 

Nfume samples oif mP.rrnernlllizedl lioweir pllaae mylonitic gneiss 

lfrom ltlhiJree ~(Pride 2Jrndl New S&oodlardl mines and Little 

Golldlellll piriOOJ!reC~) conttrullll Momallouxs OOJrncentrations of gold 

(3 samplies, um pplb, 200 ppb, mud! 200 ppb), silver (3 

samplies mllllgmg from 1 \1o 2.1 ppm), arsenic, bismuth, antimony, coppell", coball~ and! iron ~ weiR as slightly anomalous conceJrnarn.tions ofau.mgsum (Eppmgeir, 1990a, b). Heavyminemll-co~rncentrnte samples (3 ttottll) contain anomalous 

co~rnce~rnttatiolllls of coppell", lieadl, aungsten, !barium, and rron 

andlliesseir runmmas of iliorium. Mlineirals lin heavy-mineralconce~rnltlm.tte smnpRes P.JrncRudle calcitte, malachite, chrysocolla, 

oodlbmtte (Ewingeir, 1990a, 1b). Tmce amounts of galena 

were dlerecaedl fum a samplle from ilie Pride mine area 

GoRdl w~ d!et.ecttedl fum only 10 peircent of ilie creosotebush Mdl palloverr'dle samplles (Eppingeir, 1990~ b). The 

maJdmum co~rnceJrntrations d!eteirminedl were 6 ppb for 

creosorebuslhl, 13 ppb foir blue paioveirde, and 4 ppb for 

Ritttle-liealf paloveirdle. Bocoose bacl\cgiroundl Revels appeair 1t0 

100 aooua 0.1 lPJPlb, weHR lbeliow !tRue 1 pplb llimi~ of dleterminatiollll, samples with d!et.ecttedl gold! are ooomalous, andl iliose 

slires wheire awo Oir more plana smnplies contAin d!etectablle 

golidl are especially noteworthy (fng. 3). The highest concenttations of golidl were d!etecttedl nJrn the paloverde sample 

firom site 35, where samplles of creosotebush and paloverde 

also conaain anomalous concentrations of barium and moRyMerium (fig. 3). 

Coppell" anomaHes fum planas wiiliillll the swdly area are 

geJrneraHy Iresttictedl ao areas having mowHll coppell" occurre~rnces. Two exceptions are sites 16 and46 (fi.g. 3), where 

ilieire me no outcirops. Sitte 46 is of particularr interes~ because of oodlitio~ anomalous concentrations of gold! and 

moRyMeJrnum lillll vegemtiollll oodllhecause of ilie high.B. cereMS 

SJPOire colll!nt Coppell" is Irelativeny immobile in most arid 

ellllvrroJrnmeJrnts and! is ilierefore reflected! m vegetation near 

ias smnrce. For e;mmple, Lovering and McCarthy (1978) 

Ireportedl \that ttwigs mulllieaves firom mesquite ttrees (Prosopis 

sp.) that mp alllcaline ground wateir near the Sierrita, Ariz., 

coppell" oirebOOy OOJrnceJrntraredl moliyMenum but did not con-
centrale copper. Yet similar samples of mesquite trees that 

grew on caprock in an acidic environment over an oxidizing pyritic copper orebody at Ray, Ariz., yielded strong 

copper anomalies. Thus, the anomalous concentrations of 

copper in vegetation samples collected in the study area 

probably indicate a nearby source. 

Analyses of creosotebush and blue paloverde revealed 

an extensive barium-rich zone in the south-central part of 

the Cactus Plain Wilderness Study Area. A cluster of four 

sites with particularly high levels in creosotebush lies immediately north of basalt in area 6 (fig. 3). Dunn and 

Hoffman (1986) found that plants growing over mineralized veins in the boreal forests of northern Saskatchewan 

contain unusually high concentrations of barium. Because 

of the shallow nature of the creosotebush roots, the bariumrich bedrock source may be near the surface. 

In sharp contrast to the limited areas marked by 

anomalous concentrations of copper, anomalous concentrations of molybdenum in the south-central part of the Cactus 

Plain Wilderness Study Area (fig. 3) show a broad dispersion halo that is associated with locally mineralized outcrops 

and with anomalous concentrations of copper and barium in 

plants. This broad molybdenum halo is consistent with the 

conclusions of Huff (1970), who delineated a widespread 

area of anomalous concentrations of molybdenum in mesquite samples around known alluvium-covered copper deposits in the Pima mining district of southern Arizona Probably because of such large dispersion halos for molybdenum, Chaffee (1976) considers copper a more useful metal 

for defining areas for detailed exploration, though molybdenum is more useful in broad reconnaissance prospecting. 

Creosotebush samples from the Pride and New Standard 

mines and the Little Golden prospect in area 10 (fig. 3) are 

unique because they contain exceptionally high concentrations 

of copper and, more importantly, the only detectable amounts 

of bismuth in vegetation. These anomalous concentrations 

of bismuth mirror the bismuth-rich rocks of area 10. 

Bacillus cereus 

Of the five mineralized areas sampled, only soils from 

the New Standard mine (area 10, fig. 3) yielded high amounts 

of B. cereus in spores (Eppinger, 1990a, b). Single-site B. 

cereus anomalies were common, generally without associated 

anomalies in vegetation, rock, or heavy-mineral-concentrate 

samples. These facts, coupled with evidence of high withinsite variability, diminish the usefulness of this microbiological 

method, by itself, to assess the resource potential of the 

study area. Reasons are unclear for the general lack of B. 

cereus anomalies in mineralized areas or for B. cereus 

anomalies without coincident anomalies in other sample 

media. Cattle activity throughout the region may have affected bacterial populations enough to overshadow any B. 

cereus anomalies related to metal enrichment. Alternatively, 

perhaps this bacterium simply does not respond predictably 

to mineralized areas in this region. Nevertheless, the locality of the highest observed B. cereus spore count overlaps an 

area where the creosotebush and paloverde contain anomalous 

concentrations of metals (fig. 3). 

Interpretation 

Three suites of elements are found in anomalous concentrations in rock and (or) heavy-mineral-concentrate 

samples from five mineralized bedrock areas at various localities around the Cactus Plain and East Cactus Plain Wilderness Study Areas (areas 1, 7, 8, 9, and 10; fig. 3). These 

are: (1) an anomalous silver-arsenic-bismuth-copper suite 

in four of the five areas; (2) an anomalous gold-bariummolybdenum-lead-antimony-zinc suite that is found in three 

of the five areas; and (3) an anomalous tungsten-manganese-strontium suite that is found in two of the five areas. 

Metals in anomalous concentrations in creosotebush 

and paloverde from these five bedrock areas include gold, 

copper, molybdenum, and, in area 10, bismuth. Mineral 

deposits in these areas are interpreted as being related to 

Tertiary detachment faults in the region (Spencer and Welty, 

1986, 1989). Though bedrock is sparse, many of the elements of the previously described suites are found in 

anomalous concentrations in rock and heavy-mineral-concentrate samples collected within the study area. Areas 2, 

5, and 6 are noteworthy for being anomalous in at least 6 of 

the 13 elements. 

Elements in anomalous concentrations in rocks and 

heavy-mineral-concentrate samples from area 2 most likely 

reflect areally extensive metal enrichment along shears and 

quartz veins in lower plate rocks related to the nearby mineralizing system in the Green Streak mine area. In area 2, 

the gold-barium-copper-molybdenum-lead-strontium-tungsten geochemical suite in rocks and heavy-mineral-concentrate samples, the occurrence of specularite, chrysocolla, 

fluorite, oxidized pyrite boxwork, and vein quartz in samples 

from isolated outcrops, and the large copper anomaly and 

local gold anomaly in vegetation suggest that similar deposits to those in the Green Streak mine area may be concealed under alluvium surrounding the isolated bedrock. 

The silver-arsenic-barium-beryllium-cadmium-cobaltmolybdenum-lead-thorium-zinc suite in rocks and heavymineral-concentrate samples and the anomalous concentrations of molybdenum in vegetation in area 5 were detected 

in samples collected along iron- and manganese-oxide-rich 

faults cutting upper plate Paleozoic rocks. Most of these 

metals are readily scavenged by iron and manganese oxides, a process undoubtedly responsible for much of the 

metal enrichment. Nevertheless, the assemblage of metals 

is similar to that for detachment fault-related deposits. The 

Mineral Resources of the Cactus Plain and East Cactus Plain Wilderness Study Areas, La Paz County, Arizona 017 
possibility that the~scavenged metals have been remobilized 

· and are derived from concealed deposits cannot be ruled out. 

A silver-gold-barium-berylliwn-copper-molybdenummanganese-tin suite is found in area 6 in rock and heavymineral-concentrate samples derived from postdetachment, 

locally vented basalts. This assemblage and the occurrence 

of chrysocolla and azurite in quartz and calcite veins along 

faults suggest the possibility of leakage halos related to 

remobilization of metals in underlying detachment faultrelated deposits. Analyses of vegetation samples surrounding and east of area 6 yield widespread anomalous concentrations of barium and molybdenwn and local anomalous 

concentrations of copper and gold, including the highest 

·gold concentrations in vegetation found in this study. Thus, 

the leakage halos may be much more extensive than the 

limited bedrock exposures in area 6 indicate. 

Geochemical anomalies in rock and heavy-mineralconcentrate samples in areas 3 and 4 may be related to a 

similar remobilization of underlying deposits, though these 

anomalies are less extensive, and associated veins or shears 

were not observed. However, molybdenum and gold 

anomali~s in vegetation are positive criteria for possible 

concealed deposits in these areas. 

Geophysical Studies 

The Cactus Plain and East Cactus Plain Wilderness 

Study Areas are covered by regional gravity anomaly data 

(Lysonski and others, 1980; Aiken and others, 1981; Defense Mapping Agency Aerospace Center, 1974, 1975), reFigure 4. Bouguer gravity anomaly map of Cactus Plain and. East Cactus Plain Wilderness Study Areas, La Paz County, Arizona, 

and surrounding region. Contour interval, 1 milligal; grid interval, 1.5 km (5,000 ft); hachures in direction of gravity low. 

Squares denote observation points; see text for discussion of labeled anomalies. 

018 Mineral Resources of the Wilderness Study Areas: Havasu Region, Arizona 
gional aeromagnetic anomaly data obtained in the National 

Uranium Resource Evaluation (NURE) program (U.S. Department of Energy, 1979a, b; LKB Resources, Inc., 1980), 

and detailed aeromagnetic anomaly data (U.S. Geological 

Survey, 1981) having sufficient resolution to defme anomalies of 1 mi2 or larger. Contours of complete (terrain-corrected) Bouguer gravity anomalies are defined by about 45 

observation points, most of which immediately surround 

the study area (fig. 4). Contours of total-field magnetic 

anomalies are defmed by five surveys having differing flight 

specifications. Northwest of lat 34° N., long 114° W., one 

survey was flown east-west at 0.5-mi spacing and 1,000 ft 

altitude (U.S. Geological Survey, 1981) and another survey 

was flown east-west at 3-mi spacing and 400 ft altitude 

(U.S. Department of Energy, 1979a). Northeast of this coordinate, lines were flown east-west at 1-mi spacing and 

400ft altitude (U.S. Department of Energy, 1979b). Southeast and southwest of this coordinate, lines were flown eastwest at 3 mi spacing and 400 ft altitude (LKB Resources, 

Inc., 1980). These data were merged to produce an aeromagnetic map that covers a large region (fig. 5) and aeromagnetic maps that cover only the study area (figs. 6 and 7). 

The NURE magnetic anomaly data northeast of lat 

34° N., long 114° W. were previously reprocessed (DeWitt 

and others, 1988) and for this investigation were merged 

mathematically with all other NURE data and reprocessed 

using algorithms and computer programs of the Branch of 

Geophysics (1989). The resulting aeromagnetic data (fig. 

6) show spatial relationships of broad anomalies defined by 

sparse data of similar resolution and shows most importantly if these anomalies continue across various aeromagnetic survey boundaries. The detailed U.S. Geological 

Survey aeromagnetic data northwest of lat 34° N., 114° W. 

(fig. 7), recompiled from original aircraft data for this investigation, cover about 80 percent of the Cactus Plain Wilderness Study Area and are useful for judging the quality of 

the sparse NURE data and for assessing in detail some 

geologic sources of anomalies. For example, the 

Figure 5. Residual total-intensity aeromagnetic map of the Whipple, Buckskin, and northern Plomosa Mountains, Arizona and 

California. Contour interval, 20 nanoteslas. Hachured in direction of lower values. 

Mineral Resources of the Cactus Plain and East Cactus Plain Wilderness Study Areas, La Paz County, Arizona 019 
conspicuous highs at about lat 34° 10' N., long 114° 15' W. 

(AI on fig. 6) and lat 34° 04' N., long 114° 12' W. (A2 on 

fig. 6) based on the NURE data are largely artificial but 

other anomalies are generally consistent with patterns shown 

on the detailed map (fig. 7). 

Gravity Data 

The gravity anomaly map (fig. 4) shows that the study 

~is surrounded by prominent lows to the east (GL1) and 

north (GL2) and by prominent highs to the west (GH1) and 

south (GH2). Data east and northeast of the study area are 

sparse, limiting their usefulness for drawing specific conclusions about subsurface density contrasts. Between the 

highs~ low GL3 traverses the south-central part of the CacBOUNDARY 

OF 

CACTUS PLAIN 

34o WILDERNESS 

00' STUDY AREA 

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I ( I 

MH4 

tus Plain Wilderness Study Area and is flanked by gravity 

plateau GH3 at its north margin. Where the gravity anomalies lie over bedrock, highs tend to be associated with highdensity granitic and metamorphic rocks in the lower plates 

of the detachment faults, whereas the lows tend to be associated with low-density sedimentary rocks and sediments in 

a veneer or basin fill above the bedrock. Basin fill underlying the region of low GL3 is inferred to have a maximum 

thickness of about 3,000 to 3,500 ft, consistent with estimates of Oppenheimer and Sumner (1980), on the basis of 

drillhole data and gravity modeling. Fill underlying GLI 

may have a maximum thickness of as much as 1,000 ft, . 

although this estimate remains highly uncertain because of 

the sparseness of data. Where sedimentary rocks are overlain or intruded by high-density basalt, the basalt is too 

vesicular or too thin (small in volume) to increase signifi200 

Ht· i_/ .......... / /--

.. I .... 

./ I I 

APPROX]MATEBOUNDARY 

OF 

EAST CACTUS PLAIN 

Wll.DERNESS STUDY 

Figure 6. Aeromagnetic anomaly map of. Cactus Plain and East Cactus Plain Wilderness Study Areas, La Paz County, Arizona, 

and surrounding region. Contour interval, 20 nanoteslas; grid interval, 1.5 km (5,000 ft); hachures in direction of lower anomaly 

values; dotted lines represent flightline traces; labeled anomalies discussed in text Compiled from National Uranium Resource 

Evaluation (NURE) program data. 

020 Mineral Resources of the Wilderness Study Areas: Havasu Region, Arizona 
cantly the integrated density and gravity response. Rocks 

of greatest density in and near the study areas are local 

occurrences of specularite .breccia, massive iron oxide, and 

sulfide-bearing breccia in the detachment faults and related 

high-angle faults in the upper plate. Though these rocks 

have bulk densities that range from about 3.0 to 3.8 g/cm3 

(grams per cubic centimeter), their volumes are too small to 

generate highs observable on the regional gravity anomaly 

map. These high-density rocks could only~ detected and 

followed in the subsurface by detailed gravity profiles having a spac.ing no larger than about 25 ft. 

Aeromagnetic Data 

The residual total-intensity aeromagnetic field for the 

800 mil region surrounding the Cactus Plain and East Cactus Plain Wilderness Study Areas reveals four pertinent features (fig. 5). (1) A striking contrast in magnetic expression is evident between the postextension volcanic rocks, 

chiefly basalts, that produce intense short-wavelength 

anomalies and the rocks affected by the extensional deformation that produce much more subdued and longer wavelength anomalies. The boundary between these two magnetic domains traces out an arc of a circle centered on the 

southeast comer of the map. (2) Within the terrane lacking 

postextension rocks, the aeromagnetic data traces out long 

wavelength, northeast-trending anomaly highs and lows that 

correspond approximately to corrugations associated with 

the detachment fault, where the mylonitic rocks in the lower 

plate crop out in antiformal arches and the faulted rocks in 

the upper plate crop out in synformal troughs (Spencer and 

Reynolds, 1989a). Metallic mineral deposits are commonly 

Figure 7. Aeromagnetic anomaly map of a region northwest of lat 34° N., long 1 14° W. that includes part of the Cactus Plain 

Wilderness Study Area, La Paz County, Arizona. Contour interval, 20 nanoteslas; grid interval, 0.25 km (800 ft); hachures in 

direction of lower anomaly values; dotted lines represenrflightline traces. Compiled from U.S. Geological Survey data. 

Mineral Resources of the Cactus Plain and East Cactus Plain Wilderness Study Areas, La Paz County, Arizona 021 
preserved in the ttoughs (Spencer and Welty, 1989). The 

broad anomaly trends associated with lower plate corrugations cannot be ttaced through the belt of short-wavelength 

anomalies produced by the postextension basaltic rocks 

concealed beneath Cactus Plain. (3) Northwest-trending 

gradients within the aeromagnetic data cut across the northeast-trending highs and lows. Where these gradients overlie bedrock, they correspond to northwest-trending highangle faults. Therefore, buried northwest-trending faults 

can be inferred in areas of alluvial rover. (4) An area of 

strong field disturbances on the southern margin of the map 

overlies the Bouse Hills, where Proterozoic, Mesozoic, and 

Tertiary volcanic, plutonic, and metamorphic rocks crop 

out 

The NURE aeromagnetic anomaly map (fig. 6) shows 

that a northwest-trending belt of anomalies, primarily highs 

(MH1, MH2, MH3, and MH4}, ttaverses the center of the 

Cactus Plain Wilderness Study Area, extending from aregion capped by basalt north of the study area (MH1) to a 

region of granitic and metamorphic rocks south of the study 

area (MH4). The map also shows that small-amplitude 

highs are generally associated with granitic and metamorphic rocks (MH5, MH6, and MH7 and probably MH8 and 

MH9) and that large-amplitude highs are associated with 

basalt (MH1 and probably MH2 and MH3). Trachytic and 

rhyolitic flows and tuffs adjoining the study areas on the 

north (ML1), volcanic and sedimentary rocks of the Bouse 

Hills south of the study area, and sedimentary rocks of the 

Bouse Formation in and east (ML2) of the study area do 

not generate significant anomalies and are inferred to be 

only slightly magnetic. The specularite breccia, massive iron 

oxide (mostly hematite), and sulfide-bearing breccia of previously noted high density have only weak magnetizations 

and are not aeromagnetic anomaly producers. 

The U.S. Geological Survey aeromagnetic anomaly 

map (fig. 7) shows that the broad NURE anomalies of the 

northwest-trending belt consist of numerous local highs 

and lows; these highs and lows reflect in detail structural 

trends of basaltic flows and intrusions, probable occurrences 

of reversed or anomalously directed total magneti~tion 

(sum of induced remnant magnetization) of basalt, local 

variations of basalt-covered topography, and subtle changes 

in basalt thickness. For example, short-wavelength lows 

are typically larger in amplitude than short-wavelength 

highs, and many of these lows do not appear north of 

counterpart highs, as would be expected if the total magnetization were normally directed. Of significance are the 

short-wavelength anomalies that indicate basalt is pervasive 

at shallow depth beneath a cover of sand dunes at least as 

far south as lat 34° N. Furthermore, both maps, when 

considered together, indicate that the belt of anomalies is 

caused by a combination of basalt and older granitic and 

metamorphic rocks and that the granitic and metamorphic 

rocks may underlie basalt in the northern part of the Cactus 

Plain Wilderness Study Area (near GH1, fig. 4). The 

small flightline spacing of this survey permits development of maps showing where boundaries of buried magnetic rocks are likely to be present (Branch of Geophysics, 

1989). Such maps showing crest lines and points of maximum horizontal gradients of pseudogravity anomalies were 

prepared and used, in part, to estimate the subsurface horizontal extent of magnetic rocks. 

Postdetachment sediment and sedimentary rock covering the extended upper plate and lower plate rocks is a 

thin veneer less than 500 ft thick, except where it is inferred 

to thicken to as much as 3,500 ft on the basis of the gravity 

low's magnitude. Therefore, any mineral occurrence that 

might be postulated to occur near the detachment surface 

would be generally accessible for recovery, except in the 

region of thickened sedimentary cover, such as in the southwestern to south-central parts of Cactus Plain Wilderness 

Study Area (area of GL3 on ·fig. 4). Such accessibility 

might be somewhat hindered, however, by the presence of 

basalt at shallow depths in a northwest-trending belt that 

ttaverses · the central part of the study area (area of GH3, 

fig. 4). 

The specularite breccia, of perhaps greatest interest 

because similar rocks contain abundant gold at the Copperstone mine 10 mi to the southwest, is sufficiently dense to 

be detected and followed in the subsurface, provided that 

very detailed, high-precision gravity surveys are made. This 

breccia, though weakly magnetic, could probably be detected and followed by high-precision, ground-based magnetic gradiometer surveys. 

Natural Radioelement Data 

Natural radioelement distributions in the Cactus Plain 

~d East Cactus Plain Wilderness Study Areas were evaluated by examination of available data from aerial gammaray spectrometry surveys of the Needles (U.S. Deparunent 

of Energy, 1979a) and Prescott (U.S. Department of Energy, 

1979b) 1 o by 2° quadrangles. These surveys acquired aerial 

gamma-my spectrometry data along 3-mi (Needles) and 1-

mi-spaced (Prescott) east-west flightlines at 400 ft above 

ground level. Three flightlines cross the part of the study 

area within the Needles quadrangle and have about 5 percent ground coverage, because an aerial gamma-ray system 

at 400 ft above ground level effectively measures terrestrial 

gamma radiation in an 800-ft-wide swath along the flightline. Six flightlines cross the part of the study area within 

the Prescott quadrangle and provide about 15 percent ground 

coverage. The respective 5 percent and 15 percent coverages represent a reconnaissance sampling of the near-surface (0- to 18-in. depth) distribution of the natural radioelelnents potassium (K), uranium (eU), and thorium (eTh). 

The prefiX "e" for equivalent denotes the potential for disequilibrium in the uranium and thorium decay series. 

022 Mineral Resources of the Wilderness Study Areas: HavasU Region, Arizona 
Radioelement contour maps indicate that the study 

area is characterized by radioelement concentrations of 0.8 

to 2 percent K, 1 to 3 ppm eU, and 5 to 10 ppm eTh. 

Higher concentrations of 2 to 3 ppm eU and 7.5 to 10 ppm 

eTh are present in the eastern part of the study area and 

probably reflect a relatively greater abundance of uraniumand thorium-bearing minerals in eolian deposits. For the 

study area, the concentrations detected are thought to be of 

reasonable (not anomalous) level for the eolian deposits 

and other sedimentary rocks of the Bouse Formation that 

compose most of the surface material. Radioelement concentrations could not be determined for sparse outcrops of 

older sedimentary, metamorphic, and igneous rocks. 

Mineral Resource Potential 

To assess the mineral resource potential of the Cactus 

and East Cactus Plain Wilderness Study Area. regional geology, geochemistry, geophysics, mineral occurrence maps, 

mining claim records, and available ore deposit models applicable to geologic terrane in the region were studied. Because much of the study area is covered by unmineralized 

sedimentary rock, biogeochemical and geophysical data are 

the most useful in assessing the mineral resource potential. 

An estimate of the level of resource potential and degree of 

certainty for each tract was made using criteria outlined in 

the "Appendixes." Throughout this discussion, mineral resource potential refers only to undiscovered mineral resources. 

Areas having mineral resource potential for gold, silver, copper, lead, zinc, barite, fluorite, manganese, beryllium, and uranium resources were delineated. Applicable 

metallic ore deposit models for the study areas include detachment fault-related base- and precious-metal deposits 

(Wilkins and Heidrick, 1982; Wilkins and others, 1986; 

Spencer and Welty, 1986, 1989; Spencer and others, 1988), 

stratabound and fault controlled manganese deposits (Spencer and Welty, 1986), and stratabound uranium and vanadium deposits (Sherbourne and others, 1979; Cox and Singer, 

1986; Spencer and Welty, 1986). Some areas have resource potential for sand and bentonitic clay. 

Base and Precious Metals 

Base- and precious-metal mines and prospects adjacent 

to the Cactus Plain and East Cactus Plain Wilderness Study 

Areas have been worked intermittently since the late 1800's 

(Keith, 1978; Keith and others, 1983a, b). The mineral 

occurrences are epithermal and contain iron-bearing minerals, usually specularite and less commonly pyrite, chalcopy- · 

rite, and magnetite. Most mines have produced copper and 

lesser amounts of lead and zinc (Spencer and Welty, 1989). 

Several mines have also produced gold and silver, either as 

primary commodities or as by-products. The mines are 

developed in replacement deposits in carbonate rocks, in 

epithermal veins in faults, in veins, and in replacement 

deposits localized in high- and low-angle faults in and above 

the detachment faults (Spencer and Welty, 1989). The Moon 

Mountains detachment fault in the northern Dome Rock 

Mountains underlies the Copperstone mine, the largest producer of gold in Arizona (Spencer and others, 1988). Other 

past productive mines are along the Buckskin-Rawhide 

detachment fault system in the Buckskin Mountains 

(Cienega, Mammon, Pride, and Midway mineral districts) 

and in the Plomosa Mountains (Northern Plomosa mineral 

district). All the deposits are associated with detachment 

faults that project beneath the study area. 

On the basis of regional occurrences of metallic mineral deposits, Spencer and others (1988) and Spencer and 

Welty (1989) argued that the Cactus Plain and East Cactus 

Plain Wilderness Study Areas must be classified as having 

a high resource potential for gold, silver, copper, lead, and 

zinc. The geochemical and geophysical data obtained in 

this study support this appraisal. This appraisal, however, 

ignores the economic problems for any future development 

of potential ore deposits resulting from local significant 

thickness (greater than 300 ft) of postmineralization basalts 

and sedimentary rocks that underlie parts of the study area. 

Following Spencer and others (1988) and Spencer and 

Welty (1989), the entire study area is assigned high potential 

for gold, silver, copper, lead, and zinc. Three specific areas 

have a certainty level of D, whereas the remaining parts of 

study area have a certainty level of B (fig. 2). The three 

areas with a certainty level of D are immediately southwest of the Green Streak mine along the northeast border of 

the East Cactus Plain Wilderness Study Area, in the northwestern part of the Cactus Plain Wilderness Study Area, 

and in the southeastern part of the Cactus Plain Wilderness 

Study Area. The certainty of level D is based primarily on 

geochemical data and the presence of the sparse bedrock 

outcrops in the area. Two other observations support the 

certainty level assignment; these are ( 1) most metallic deposits in the extended terrane are preserved within the synformal troughs where the upper plate rocks have not been 

removed by erosion and (2) the aeromagnetic data, which 

suggest that these synformal troughs project into the study 

area. 

Barite and Fluorite 

Barite and fluorite have been produced locally from 

mines in the Northern Plomosa and Bouse mineral districts 

(Stewart and Pfister, 1960; Keith, 1978). These minerals 

are in veins and faults in upper plate Tertiary volcanic and 

sedimentary rocks adjoining the southern edge of the Cactus 

Mineral Resources of the Cactus Plain and East Cactus Plain Wilderness Study Areas, La Paz County, Arizona 023 
Plain Wilderness Study Area. Stream-sediment and biogeochemical data in this area indicate a large halo of barium 

enrichment around these deposits. Because of these mineral occurrences and the geochemical anomalies, this area 

is assigned high resource potential with a certainty level of 

D for barite and fluorite (fig. 2). 

Geochemical data from stream-sediment and rock 

samples indicate the possible presence of unexposed barite 

in the northwestern part of the Cactus Plain Wilderness 

Study Area. Because of the lack of exposed mineralized 

ground, this area is assigned a moderate potential for barite 

with a certainty level of C (fig. 2). There is no .evidence 

available to assess the mineral resource potential of fluorite 

in this area. 

Manganese 

Mines in the Northern Plomosa and Bouse mineral 

districts have produced small amounts of manganese 

(Farnham and Stewart, 1958; Keith, 1978). The deposits 

are in high-angle faults cutting the unmetamorphosed upper 

plate Tertiary volcanic and sedimentary rocks. Outcrops of 

upper plate Tertiary volcanic and sedimentary rocks are 

only in, or adjoining, the southeastern part of and northwest 

corner of the Cactus Plain Wilderness Study Area. Therefore, the southeastern comer in the Cactus Plain Wilderness 

Study Areas is assigned moderate resource potential for 

manganese with a certainty level of C because of the past 

production of manganese from nearby areas. The northwestern comer of the Cactus Plain Wilderness Study Area 

also is assigned moderate potential, though with a certainty 

level of B because no occurrences of manganese are known 

in this area (fig. 2). 

Uranium 

Scarborough and Wilt (1979) noted weak evidence 

for uranium mineralization along a low-angle fault separating middle Tertiary limestone from crystalline rocks north 

of Osborne Wash. These moderately to steeply dipping 

rocks were deformed during extensional deformation. Uranium occurs in the middle Tertiary sedimentary rocks elsewhere in the extended terrane of this region (Welty and 

others, 1985). Most notable is uranium at the Anderson 

mine in the Date Creek Basin about 40 mi to the northeast 

(Sherbourne and others, 1979). The association of uranium 

with Tertiary sedimentary rocks suggests that the two areas 

in the northwestern and southeastern parts of the Cactus 

Plain Wilderness Study Area where these rocks crop out 

have low potential with a certainty level of B for uranium 

(fig. 2). The presence of thorium in the geochemical data 

supports this assessment 

Beryllium 

Trace amounts of beryllium are present in manganese 

ore produced from the southwestemmost Bouse Hills (Keith, 

1978). The mines are developed in· northwest-trending 

fractures and faults that cut Tertiary volcanic rock. The 

faults are in the upper plate of the detachment fault The 

association of trace beryllium with manganese ore and 

anomalous concentrations of beryllium are the basis for two 

areas in the northwestern and southeastern parts of the Cactus J>lain Wilderness Study Area being assigned low potential for beryllium, certainty level B. 

Bentonitic Clay 

A few hundred tons of bentonitic clay were produced 

for local drilling muds from sedimentary horizons adjacent 

to the Bouse Hills (Wilson and Roseveare, 1949; Keith, 

1978). The deposits are in subhorizontal beds that are reported to be altered tuffaceous sedimentary rocks. Tuffaceous horizons are found in the region within the highly 

faulted and extended volcanic rocks, in postdetachment trachytic and rhyolitic volcanic centers, and as horizons in the 

Bouse Formation. On the basis of these occurrences, the 

entire study area is assigned low resource potential with a 

certainty level of B for bentonitic clay (fig. 2). 

Sand 

Extensive eolian sand covers the southern three-quarters of the East Cactus Plain Wilderness Study Area and the 

northern half of the Cactus Plain Wilderness Study Area. 

As noted previously, this sand is unsuitable for use in glass 

production though it is suitable for foundry, fracturing, and 

abrasive materials. These areas are assigned high resource 

potential with a certainty level of D for sand (fig. 2). 

Oil and Gas 

Despite a significant number of oil and gas leases and 

lease applications, the Cactus Plain and East Cactus Plain 

Wilderness Study Areas have no resource potential for oil 

and gas with a certainty level D. This assignment is justified because of the general lack of hydrocarbon-bearing 

source or reservoir rocks, because of the abundance of 

metamorphic rocks in the ranges surrounding the study area, 

and because the unmetamorphosed rock, where present in 

the region, generally forms thin deposits (fig. 2). 

024 Mineral Resources of the Wilderness Study Areas: Hav-.. Region, Arizona 
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1987, Geology of the Battleship Peak area, Buckskin Mountains, La Paz Co\Dlty, Arizona: Arizona Bureau of Geology 

and Mineral Technology Miscellaneous Map MM-87-B, 

scale, 1:8,000. 

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

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

Metzger, D.O., 1968, The Bouse Formation (Pliocene) of the 

Parker-Blythe-Cibola area, Arizona and California: U.S. 

Geological Survey Professional Paper ~D.p. D126-D136. 

Metzger, D.O., Loeltz, O.J., and Irelina, Burdge, 1973, Geohydrology of the Parker-Blythe-Cibola area, Arizona and California: U.S. Geological Survey Professional Paper 486-G, 

130p. 

Motooka, J.M., 1988, An exploration geochemical technique for 

the determination of preconcentrated organometallic halides 

by ICP-AES: Applied Spectroscopy, v. 42, p. 1293-1296. 

Qppenheimer, J.M., and Sumner, J.S., 1980, Depth to bedrock 

map, Basin and Range province, Arizona: Tucson, Laboratory of Geophysics, Department of Geoscience, University of 

Arizona, scale 1:500,000. 

Parduhn, N.L., 1987, The ecology and distribution of Bacillus 

cereus and other microorganisms in soils associated with gold 

deposits: Golden, Colorado, Colorado School of Mines, Ph.D. 

dissertation, 193 p. 

Parduhn, N.L., Watterson, J.R., and Silberman, M.L., 1986, Distribution of Bacillus cereus spores in soil over four subsurface 

gold deposits, a progress report, in Dean, W .E., ed., Organics 

and Ore Deposits: Proceedings of the Denver Region Exploration Geologists Society Symposium, April, 1985, Denver, 

p. 115-118. 

Rehrig, W.A., and Reynolds, S.J., 1980, Geologic and geochronologic reconnaissance of a northwest-trending zone of metamorphic complexes in southern and western Arizona, in 

Crittenden, M.D., Jr, Coney, P.J., and Davis, G.H., eds., Cordilleran metamorphic core complexes: Geological Society of 

America Memoir 153, p. 131-158. 

Reif, D.M., and Robinson, J.P, 1981, Geophysical, geochemical, 

an4 petrographic data and regional correlation from the Arizona State A-1 Well, Pinal County, Arizona: Arizona Geological Society Digest, v. 13, p. 99-109. 

Ryder, R.T., 1983, Petroleum potential of wilderness lands in Arizona, in Miller, B.W., ed., Petroleum potential of wilderness 

lands in the western United States: U.S. Geological Survey 

Circular 902, p. Cl-C22. 

Scarborough. Robert, and Wilt, J.C., 1979, A study of uranium 

favorability of Cenozoic sedimentary rocks, Basin and Range 

Province, Arizona; Part I, General geology and chronology 

of pre-late Miocene Cenozoic sedimentary rocks: Arizona 

Bureau of Geology and Mineral Technology Open-File Report 79-1; 101 p. 

Sherbourne, I.E., Jr., Buckovic, W.A., DeWitt, E.B., Hellinger, 

T.S., and Pavlak, SJ., 1979, Major uranium discovery in 

volcaniclastic sediments, Basin and Range Province: 

026 Mineral Resources of the Wilderness Study Areas: Havasu Region, Arizona 
American Association of Petroleum Geologists Bulletin. v. 63, 

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Spencer, J.E., compiler, 1989, Compilation geologic map of the 

Buckskin and Rawhide Mountains, west-central Arizona, in 

Spencer, J.E., and Reynolds, S.J. ed., Geology and mineral 

resources of the Buckskin and Rawhide Mountains, westcentral Arizona: Arizona Geological Survey Bulletin 198, 

scale 1: 100,000. 

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Tertiary tectonics of Arizona and southeastern California, in 

Beatty, Barbara, and Wilkinson, P .A.K., eds., Frontiers in 

geology and ore deposits of Arizona and the southwest: 

Tucson. Arizona, Geological Society Digest, v. 16, p. 102-

107. 

---eeds., 1989a, Geology and mineral resomces of the Buckskin and Rawhide Mountains, west-central Arizona: Arizona 

Geological Survey Bulletin 198, 279 p. 

--1989b, Introduction to the geology and mineral resomces 

of the Buckskin and Rawhide M01mtains, in Spencer, J.E., and 

Reynolds, S.J., eds., Geology and mineral resomces of the 

Buckskin and Rawhide Mountains, west-central Arizona: 

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--1989c, Tertiary structure, stratigraphy, and tectonics of the 

Buckskin Mmmtains, in Spencer, J.E., and Reynolds, S.J., edS., 

Geology and mineral resources of the Buckskin and Rawhide 

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Spencer, I.E., and Welty, J.W., 1986, Possible controls of baseand precious-metal mineralization associated with Tertiary 

detachment faults in the lower Colorado River trough, Arizona and California: Geology, v. 14, p. 195-198. 

--1989, Geology of mineral deposits in the Buckskin and 

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of Geology and Mineral Technology Fieldnotes, v. 18, no. 2, 

p.1-3. 

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U.S. Bureau of Mines Report of Investigations 5651, 89 p. 

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volcanic rocks, west-central Arizona: Isochron/West, no. 24, 

p. 25-29. 

--1983, Origin of bimodal volcanism, southern Basin and 

Range province, west-central Arizona: Geological Society of 

America Bulletin, v. 94, p. 1005-1019. 

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Rapid analysis for gold in geologic materials, in U.S. Geological Survey Research, 1968: U.S. Geological S\lrvey Professional Paper 600-B, p. B130-132. 

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Geological Survey Circular 831, 5 p. 

U.S. Geological Survey, 1981, Aeromagnetic map of the Needles 

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Watterson, J.R., 1985, A procedure for estimating Bacillus cereus 

spores in. soil and stream sediment samples--a potential exploration technique: Journal of Geochemical Exploration, v. 

23, p. 243-252. 

Watterson, J.R., Nagy, L.A., and Updegraff, D.M., 1986, Penicillin resistance in soil bacteria is an index of soil metal content 

near a porphyry copper deposit and near a concealed m&Ssive 

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and Watterson, J.R., eds, Mineral exploration: Biological 

systems and organic matter, [W.O. Rubey, v. 5]: Englewood 

Cliffs, New York, Prentice Hall, p. 328-350. 

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R.A., 1985, Geology and production of Middle Tertiary mineral districts in Arizona: Arizona Bmeau of Geology and 

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metal mineralization related to low-angle tectonic featl.D'es in 

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mineralization along the Riverside detachment fault, Riverside County, California, in Schafer, R.W., Cooper, J.J., Vikre, 

P.O., eds., Bulk mineable precious metal deposits of the 

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northwestern Yuma Co\Dlty, Arizona: Rolla, University of 

Missouri, M.S. thesis, 64 p. 

Mineral Resources of the Cactus Plain and East Cactus Plain Wilderness Study Areas, La Paz County, Arizona 027 
APPENDIXES 
DEFINITION OF LEVELS OF MINERAL RESOURCE POTENTIAL 

AND CERTAINTY OF ASSESSMENT 

LEVELS OF RESOURCE POTENTIAL 

H HIGH mineral resource potential is assigned to areas where geologic, geochemical, and geophysical char-: 

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

indicate a high· degree of likelihood for resource aq:umulation, where data support mineral-deposit models 

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

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

have been active in at least part of the area. 

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

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

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

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

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

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

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

· been mineralized. · 

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

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

moderate, or high level of resource potential. 

LEVELS OF CERTAINTY 

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

B Available information only suggests the level of mineral resource potential. 

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

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

l ...J 

< i= 

z 

I.U 

b 

c.. 

I.U 

u 

o=: 

:::> 

0 

V) 

I.U 

o=: 

u.. 

0 

...J 

I.U 

> I.U 

...J 

A 

U/A 

UNKNOWN POTENTIAL 

Abstracted with minor modifications from: 

B c 

H/B H/C 

HIGH POTENTIAL HIGH POTENTIAL 

fv\/B tvVC 

MODERATE POTENTIAL MODERATE POTENTIAL 

UB uc 

LOW POTENTIAL LOW POTENTIAL 

LEVEL OF CERTAINTY 

D 

H/D 

HIGH POTENTIAL 

fv\/D 

MODERATE POTENTIAL 

UD 

LOW POTENTIAL 

N/D 

NO POTENTIAL 

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

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

Geological Survey Bulletin 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. 

030 Mineral Resources of Wilderness Study Areas: Havasu Region, Arizona 
RESOURCE/RESERVE CLASSIFICATION 

IDENTIFIED RESOURCES UNDISCOVERED RESOURCES 

Demonstrated Probabi I ity Range 

Inferred 

Measured Indicated Hypothetical Speculative 

I Inferred I 

ECONOMIC Reserves Reserves ____ .!.. _____ I f---------- ~ -~- I Inferred MARGINALLY Marginal Marginal ECONOMIC Reserves Reserves 

I I 

----,---- 1---------- ~ -~-

SUB- Demonstrated Inferred 

Subeconomic Subeconomic 

ECONOMIC Resources Resources I I I 

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

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

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

Mineral Resources of the Cactus Plain and East Cactus Plain Wilderness Study Areas, La Paz County, Arizona 031 
GEOLOGIC TIME CHART 

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

EON ERA PERIOD EPOCH 

Quaternary 

Holocene 

Pleistocene 

Neogene Pliocene 

Cenozoic Subperiod Miocene 

Tertiary Paleogene Oligocene 

Sub period Eocene 

Paleocene 

Cretaceous Late 

Early 

Late. 

Meso" zoic jurassic Middle 

Early 

Late 

Triassic Middle 

Early 

Permian Late 

Phanerozoic Early 

Late 

Pennsylvanian Middle 

Carboniferous Early Periods 

Mississippian Late 

Early 

Late 

Devonian Middle 

Paleozoic Early 

Late 

Silurian Middle 

Early 

Late 

Ordovician Middle 

Early 

Late 

Cambrian Middle 

Early 

Late Proterozoic 

Proterozoic Middle Proterozoic 

Early Proterozoic 

Late Archean 

Archean 

Middle Archean 

Early Archean 

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - {3 8001)- - - - - - - - - - - - - - - - - - -

pre-Archean2 

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

032 Mineral Resources of Wilderness Study Areas: Havasu Region, Arizona 

AGE ESTIMATES OF 

BOUNDARIES IN 

MILLION YEARS {Ma) 

0.010 

1.7 

5 

24 

38 

55 

66 

f---- 96 

138 

205 

-240 

290 

-330 

360 

410 

435 

500 

1

-570 

900 

1600 

2500 

3000 

3400 

4550 
Mineral Res.ources of 

Wilderness Study Areas: 

Havasu Region, Arizona 

This volume was published as separate chapters A-D 

U.S. GEOLOGICAL SURVEY BULLETIN 1704 
U.S. DEPARTMENT OF THE INTERIOR 

MANUEL LUJAN, jR., Secretary 

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director 
CONTENTS 

[Letters designate the separately published chapters] 

(A) Mineral Resources of the Mohave Wash Wilderness Study Area, Mohave County, 

Arizona, by James G. Evans, David R. Sherrod, Randa11 H. Hill, Robert C. Jachens, 

and John R. McDonnell, Jr. 

(B) Mineral Resources of the Gibraltar Mountain and Planet Peak Wilderness Study 

Areas, La Paz County, Arizona, by Robert G. Eppinger, Jocelyn A. Peterson, 

H. Richard Blank, Jr., K. Eric Livo, Daniel H. Knepper, Jr., James A. Pitkin, Jon E. 

Spencer, Stephen J. Reynolds, Michael J. Grubensky, Terry J. Kreidler, and David 

C. Scott 

(C) Mineral Resources of the Swansea Wilderness Study Area, La Paz and Mohave 

Counties, Arizona, by Richard M. Tosdal, Robert G. Eppinger, H. Richard Blank, 

Jr., Daniel H. Knepper, Jr., Andrea J. Gallagher, James A. Pitkin, Stephanie L. 

Jones, and GeorgeS. Ryan. 

(D) Mineral Resources of the Cactus Plain and East Cactus Plain Wilderness Study 

Areas, La Paz County, Arizona, by Richard M. Tosdal, Robert G. Eppinger, James 

A. Erdman, William F. Hanna, James A. Pitkin, H. Richard Blank, Jr., Richard M. 

O'Leary, John R. Watterson, and Terry J. Kreidler. 

0 " 
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-~-~rosdal; other~~~_!RAL RE?OURCES, CAS"fUS AND E. CACfUS PLAIN WILDERNESS STUDY AREAS, ARIZONA-U.S.