Mineral resources of the Mount Tipton Wilderness Study Area, Mohave County, Arizona

Greene, Robert C., Turner, Robert L., Jachens, Robert C. jachens@usgs.gov, Lawson, William A. · 1989 · Report

The Mount Tipton Wilderness Study Area (AZ-020-012/ 042) comprises 33,950 acres in Mohave County, Ariz. At the request of the U.S.

This 1989 document, Mineral resources of the Mount Tipton Wilderness Study Area, Mohave County, Arizona, is preserved in the Mountain Man Mining Library for research and reference. Original source: pubs.usgs.gov.

I 19.3:1737-B Mineral Resources of the Mount Tipton Wilderness Study Area,89 795 Mohave County, Arizona GEORGIA TECH LIBRI,RY DEC 07 1989 GOV IS DEPOSITORY COLLECTION U.S. GEOLOGICAL SURVEY BULLETIN 1737—B U UORTMENT OF 1H INTERIOR ..RECJLANM.M.T

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Chapter B Mineral Resources of the Mount Tipton Wilderness Study Area, Mohave County, Arizona By ROBERT C. GREENE, ROBERT L. TURNER, ROBERT C. JACHENS, and WILLIAM A. LAWSON U.S. Geological Survey CARL L. ALMQUIST U.S. Bureau of Mines U.S. GEOLOGICAL SURVEY BULLETIN 1737 MINERAL RESOURCES OF WILDERNESS STUDY AREAS: BLACK MOUNTAINS REGION, ARIZONA

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 : 1989 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 Mount Tipton Wilderness Study Area, Mohave County, Arizona / by Robert C. Greene . . . let al.]. p. cm. — (Mineral resources of wilderness study areas—Black Mountains region, Arizona ; ch. B)(U.S. Geological Survey bulletin ; 1737—B) Includes bibliographical references. Supt. of Docs. no. : I 19.3:1737—B 1. Mines and mineral resources—Arizona—Mount Tipton Wilderness. 2. Mount Tipton Wilderness (Ariz.) I. Greene. Robert C. II. Series. III. Series: U.S. Geological Survey bulletin ; 1737—B. QE75.B9 no. 1737—B 557.3 s—dc20 89-600219 [TN24.A6] [553'.09791 '59] 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 Mount Tipton Wilderness Study Area (AZ-020-012/042), Mohave County, Ariz.

CONTENTS Summary B1 Abstract B1 Character and setting Identified mineral resources and mineral resource potential B1 Introduction B1 Setting B3 Previous work and present study B3 Appraisal of identified resources B3 Introduction B3 Mining and mineral exploration history B3 Mines, prospects, mining claims, and leases B3 Assessment of potential for undiscovered resources B6 Geology B6 Geochemistry B7 Geochemical results B8 Geophysics B8 Aeromagnetic data B8 Radiometric data B9 Gravity data B9 Mineral and energy resource potential B9 References cited B10 Appendixes Definition of levels of mineral resource potential and certainty of assessment B12 Resource/reserve classification B13 Geologic time chart B14 FIGURES 1. Map showing location of Mount Tipton Wilderness Study Area, Mohave County, Arizona B2 2. Map showing mineral resource potential and generalized geology of Mount Tipton Wilderness Study Area, Mohave County, Arizona B4 TABLE 1. Analytical data for samples collected by the U.S. Bureau of Mines during the mineral investigation of the Mount Tipton Wilderness Study Area, Mohave County, Arizona B6 ContentsV

Mineral Resources of the Mount Tipton Wilderness Study Area, Mohave County, Arizona By Robert C. Greene, Robert L. Turner, Robert C. Jachens, and William A. Lawson U.S. Geological Survey Carl L. Almquist U.S. Bureau of Mines SUMMARY Abstract The Mount Tipton Wilderness Study Area (AZ-020-012/ 042) comprises 33,950 acres in Mohave County, Ariz. At the request of the U.S. Bureau of Land Management, this area was evaluated for identified mineral resources (known) and mineral resource potential (undiscovered). This work was carried out by the U.S. Bureau of Mines and the U.S. Geo­ logical Survey in 1984-87. In this report, the area studied is referred to as the "wilderness study area" or simply "the study area." There are no identified mineral resources in the study area. The southernmost part of the study area is adjacent to the Wallapai (Chloride) mining district and has low mineral resource potential for gold, silver, copper, lead, zinc, and molybdenum in hydrothermal veins. This area also has a low mineral resource potential for tungsten in vein deposits and for uranium in vein deposits or pegmatites. In the central part of the wilderness study area, one small area has low mineral resource potential for uranium in vein deposits or pegmatites and another small area has low resource potential for thorium in vein deposits. The entire study area has low resource potential for geothermal energy but no potential for oil or gas resources. Character and Setting The Mount Tipton Wilderness Study Area (fig. 1) lies in westernmost Arizona between Hoover Dam and Kingman. It is in the Cerbat Mountains, part of the Basin and Range province of western North America. Granitic gneiss and hornblende gneiss of Precambrian age (see "Appen­ dixes" for geologic time chart) underlie most of the study Manuscript approved for publication May 10, 1989. area. Welded tuff, mud-flow deposits, and andesite of Tertiary age underlie small areas near the southwest and north borders of the study area. Identified Mineral Resources and Mineral Resource Potential There are no identified mineral resources in the wilder­ ness study area. The southernmost part of the study area is immediately adjacent to the Wallapai (Chloride) mining district and has low mineral resource potential for gold, silver, copper, lead, zinc, and molybdenum in hydrothermal veins (fig. 2). This area also has a low mineral resource potential for tungsten vein deposits and for uranium in vein deposits or pegma­ tites. In the central part of the wilderness study area, one small area has low mineral resource potential for uranium in vein deposits or pegmatites and another small area has low resource potential for thorium in vein deposits. The entire study area has low resource potential for geothermal energy but no potential for resources of oil and gas. 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 proc­ ess, mineral survey methods, and agency responsibilities was provided by Beikman and others (1983). The U.S. Bureau of Mines evaluates identified resources at individ­ ual mines and mineralized areas by collecting data on current and past mining activities and through field exami­ nation of mines, prospects, claims, and mineralized areas. Mineral Resources of the Mount Tipton Wilderness Study Area, ArizonaV B1

115°00' 36° 15' Las Vegas Henderson 35° 30' Searchlight

1 !e\ Y 35° 15' 35° 00' 114°45' r-- Boulder N City so0 1 co Willow Beach Lake Mohave r — DAVIS DAM , 114°00' 114°30' 114°15 Temple Bar F 1,401-11\ A r e a z ' it White Hills APPROXIMATE BOUNDARY OF MOUNT TIPTON WILDERNESS STUDY AREA (AZ-020-012/042) Oatman m co AREA OF MAP

—4 Wallapai (Chloride) mining district Kingman Hualapai Mountains Oatman mining district 30 MILES Figure 1. Map showing location of Mount Tipton Wilderness Study Area, Mohave County, Arizona. B2V Mineral Resources of Wilderness Study Areas: Black Mountains Region, Arizona

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 de­ signed to provide a scientific basis for assessing the poten­ tial for undiscovered mineral resources by determining geologic units and structures, possible environments of mineral deposition, presence of geochemical and geophysi­ cal anomalies, and applicable ore-deposit models. Gou­ darzi (1984) discussed mineral assessment methodology and terminology as they apply to these surveys. See "Appendixes" for the definition of levels of mineral re­ source potential and certainty of assessment and for the resource/reserve classification. Setting The Mount Tipton Wilderness Study Area (AZ­ 020-012/042) comprises 33,950 acres in Mohave County, Ariz., east of the Colorado River and directly east of U.S. Highway 93, the highway connecting Hoover Dam and Kingman (fig. 1). Mount Tipton, 7,148 ft high, is in the central part of the Cerbat Mountains, a north-trending range that is 32 mi long. Valleys on either side of the range lie at an altitude of about 3,000 ft; farther to the west the Black Mountains form a low ridge, then the land drops abruptly to the Lake Mohave section of the Colorado River, where the surface altitude is less than 600 ft. Previous Work and Present Study Previous geologic mapping in the Mount Tipton area consists of reconnaissance work that appears on the geo­ logic maps of Arizona (Wilson and others, 1969; Reynolds, 1988). Mineral surveys can be found in Schrader (1909) and in a resources report by the U.S. Bureau of Land Man­ agement (1983). The Wallapai (Chloride) mining district, which lies immediately south of the wilderness study area, is discussed by Dings (1951). Reconnaissance geologic mapping for the present re­ port was carried out by W.A. Lawson in the central and southern parts on the Mount Tipton and Chloride 7.5­ minute quadrangles and by R.C. Greene mostly in the western part of the Grasshopper Junction 7.5-minute quad­ rangle. Geochemical sampling and interpretation of results are mostly by R.L. Turner, and interpretation of geophysics is by R.C. Jachens. Appraisal of identified resources is by C.L. Almquist of the U.S. Bureau of Mines. Final assem­ bly and interpretation is by R.C. Greene. Aerial photographs were lent by the U.S. Bureau of Land Management office in Kingman, Ariz. William Hamilton of Quail Spring Ranch kindly provided trailer parking space and access to the wilderness study area as well as information about the locations of prospects. APPRAISAL OF IDENTIFIED RESOURCES By Carl L. Almquist U.S. Bureau of Mines Introduction In 1987, the U.S. Bureau of Mines conducted a mineral investigation of the Mount Tipton Wilderness Study Area. No leasable, locatable, or salable mineral resources were identified. This investigation included a review of literature, unpublished U.S. Bureau of Mines and U.S. Bureau of Land Management files, and mining claim and land status records; mining claim holders were contacted; prospects in the study area and adjacent areas were examined and sampled; and sample analyses were evaluated. Two U.S. Bureau of Mines geologists spent three days in the study area. They collected nine chip, grab, and select samples, which were analyzed by Chemex Labs, Inc., Sparks, Nev. Copper, lead, zinc, silver, molybdenum, arsenic, and antimony were deter­ mined by inductively coupled plasma—atomic emission analysis. Gold was determined by fire assay and neu­ tron activation analyses. The results of these analyses are listed in table 1 of this report. Mining and Mineral Exploration History Minerals-related activity in the study area has in­ cluded prospecting, locating mining claims, and oil and gas leasing; there is no recorded production of any mineral commodities. A block of lode and placer mining claims extends into the northwest corner of the study area, and one mining claim lies on the south boundary (Almquist, 1988, fig. 2). Recorded produc­ tion for the adjacent Wallapai (Chloride) mining district from 1901 to 1981 is 666.1 million lb copper, 53.2 million lb molybdenum, 80.1 million lb lead, 126.5 million lb zinc, 11.5 million troy oz silver, and 0.151 million troy oz gold (Keith and others, 1983, p. 52-53). Mines, Prospects, Mining Claims, and Leases No previously unknown mines, prospects, or mineralized areas were found during reconnaissance of mining claims in the study area. Four outcrop samples were collected at sites on the block of mining claims where assays obtained by the claim holders show that significant concentrations of base and precious metals are present. The U.S. Bureau of Mines samples, however, contain insignificant concentrations of gold, silver, copper, lead, zinc, molybdenum, arsenic, and antimony (table 1, Nos. 6-9). An effort to develop a natural spring as a water source was the only surface Mineral Resources of the Mount Tipton Wilderness Study Area, Arizona B3

Black Mountains Region, Arizona Mineral Resourcesof the Mount Tipton WildernessStudy Area, Arizona EXPLANATION 114* 15' 114' 12' 30" 114° 10' 114° 07' 30" Area having low mineral resource potential (L) Oaf B Levels of certainty of assessment Data only suggest level of potential Data give good indication of level of potential Commodities Au Gold Ag Silver Cu Copper Geo Geothermal energy Mo Molybdenum Pb Th U W Zn Lead Thorium Uranium Tungsten Zinc Correlation of map units Oaf 1- QUATERNARY Taf Twt Ta - TERTIARY Unconfomlity p-Cha - PRECAMBRIAN Oaf Taf Ta Twt p'Cgn p-Cha Descripton of map units Alluvium and alluvial fan deposits (Quatemary) Andesitic mudflow deposits (Tertiary) Andesite (Tertiary) Welded tuff (Tertiary) Granitic gneiss (Precambrian) Homblende gneiss and amphibolite (Precambrian) Contact Fault 32' 114' 17' 30" 35'

Quail Spring Ranch p'Cgn L/B Geo (entire study area) 0.-Ta pregn cregn APPROXIMATE BOUNDARY OF MOUNT TIPTON 'WILDERNESS STUDY AREA (AZ-020-012/042) 27' 30" pCgn-0 Ta Twt L/C Au, Ag, Cu, Pb, Zn, Mo, U, W p€gn Twt Oaf 2 MILES Figure 2. Mineral resource potential and generalized geology of Mount Tipton Wilderness Study Area, Mohave County, Arizona. Study area includes several blocks of privately owned land. Geology by W.A. Lawson and R.C. Greene, 1984-1987.

Table 1. Analytical data for samples collected by the U.S. Bureau of Mines during the mineral investigation of the Mount Tipton Wilderness Study Area, Mohave County, Arizona [Au analyses are by fire assay and neutron activation; Ag, Cu, Pb, Zn, Mo, As, and Sb analyses are by inductively coupled plasma-atomic emission spectrography. All analyses by Chemex Labs, Sparks, Nevada. na, not applicable; greater than; less than; ppb, parts per billion; ppm, parts per million. Sample sites shown in Almquist (1988, fig. 2)] Sample Analytical data No. Type Length Au Ag Cu Pb Zn Mo As Sb Remarks (ft) ppb ppm Grab na

Prospect pit; pegmatitic quartz mass in Precambrian gneiss. Chip

Prospect trench; pegmatitic quartz mass in Precambrian gneiss and schist. Chip Prospect pit; 1.0-ft-thick quartz vein striking N. 70° W., dipping 65° NE in Precambrian schist. Grab na Inclined shaft; quartz vein striking N. 10° W., dipping 60° NE in Precambnan gneiss; limonite. Select na 54 >100.0 9,400 1,700 Inclined shaft; quartz vein fragments in sorted pile on dump; chalcopy­ nte, azurite, malachite, limonite. Chip Outcrop of Precambnan gneiss. Chip Outcrop of Precambrian gneiss. Chip Outcrop of Precambnan gneiss. Chip 1.5-ft-thick quartz vein in outcrop of Precambnan gneiss. disturbance observed on the block of claims. Scintillo­ meter readings in the claim areas did not exceed the background level of 50 counts per second (CPS) by more than 75 percent. At a site about 0.5 mi outside the south boundary of the study area, quartz veins in iron-stained gneiss contain concentrations of copper, lead, zinc, silver, and gold (table 1, Nos. 3-5). At the surface, the veins are poorly exposed, irregular, and about 1 ft thick; none are traceable into the study area. Workings at this site consist of two inclined shafts and several pits. An additional prospect pit (table 1, No. 1) just inside the south boundary of the study area and a prospect trench (table 1, No. 2) 0.5 mi outside the study area show no significant element concentrations. In 1979, 20 shallow (40 ft deep or less) exploratory holes were drilled along the south boundary of the study area in an unsuccessful effort to locate uranium concentra­ tions in Precambrian crystalline rocks (Robert A. Laverty, former claim holder, oral commun., 1987). Scintillometer readings did not exceed the background level of 50 CPS by more than 75 percent, and no mineralized zones were observed near the drilling sites. Industrial mineral commodities in the study area have no apparent superior qualities and represent only a small fraction of abundant supplies available from established sources located elsewhere, which make those in the study area uncommercial. Ryder (1983, p. C19) rated the study area as having zero potential for the occurrence of petroleum, on the basis of the sole presence of igneous and metamorphic rocks. Nevertheless, approximately 11,500 acres were under lease for oil and gas at the time of the U.S. Bureau of Mines investigation (Almquist, 1988, fig. 3). ASSESSMENT OF POTENTIAL FOR UNDISCOVERED RESOURCES By Robert C. Greene, Robert L. Turner, Robert C. Jachens, and William A. Lawson U.S. Geological Survey Geology The Cerbat Mountains are part of the Basin and Range province of western North America, a region characterized by fault-block mountains and intervening alluvium-filled valleys. The Mount Tipton Wilderness Study Area (fig. 2) is underlain principally by granitic gneiss of Precambrian age; hornblende gneiss and amphibolite are predominant in the southern part of the area. The Precambrian rocks are locally overlain by welded tuff, andesite, and andesitic mud-flow deposits, all of Tertiary age. The hornblende gneiss and amphibolite (map unit p-Cha) are dark-gray to black rocks, mostly fine to medium B6V Mineral Resources of Wilderness Study Areas: Black Mountains Region, Arizona

grained, and form prominent outcrops on ridges and spurs. The hornblende gneiss consists of about 50 percent plagio­ clase and 50 percent hornblende with minor opaque and accessory minerals and alteration products. This mostly medium grained rock has a prominent irregular foliation; hornblende and plagioclase are each dominant in alternate lenticular layers. The hornblende gneiss grades by an increase in hornblende content into amphibolite, a finegrained rock having weak foliation and prominent lineation consisting of the same minerals but whose hornblende content approaches 100 percent. Granitic gneiss is locally interlayered with the hornblende gneiss, and quartz-feld­ spar pegmatite is also abundant. Granitic gneiss (map unit p-Cgn) is the predominant rock type underlying Mount Tipton and other parts of the Cerbat Mountains. It is a medium-to coarse-grained rock having the colors of the individual minerals: pinkish to yellowish gray (feldspar), light gray (quartz), and dark gray (biotite). Outcrops, locally forming cliffs and spires, are abundant; the mostly light yellowish gray surfaces are undergoing granular disintegration. The rocks have charac­ teristically weak foliation shown by aligned biotite grains and clots or by quartz-rich lenses. The gneiss is composed mostly of plagioclase, microcline, and quartz. Quartz content is commonly 20 to 40 percent, and the feldspars may be in any relative proportion. Biotite content is 1 to 3 percent, and trace amounts of opaque and accessory minerals make up the rest of the most commonly occurring gneiss. Less common gneisses contain minor hornblende or sillimanite with garnet. Hornblende-rich gneiss as de­ scribed above is locally interlayered, as are pegmatite and aplite (not separately mapped). Welded tuff (map unit Twt) is present locally near the ends of spurs and in small detached areas in the southwest­ ern part of the study area. The tuff is of varied texture and color; it is pinkish to brownish gray and has prominent fragmental texture. It is of andesitic to dacitic composition and contains phenocrysts of plagioclase, augite, biotite, and (locally) sanidine, each 1 percent or less. The groundmass is composed mostly of fragments of andesite or dacite which in turn contain microphenocrysts of plagioclase and augite; flattened devitrified pumice and shards are com­ mon, especially toward the top of the unit. Andesite (map unit Ta) is present locally in the south­ western part of the study area, generally overlying welded tuff but in places resting directly on gneiss. The andesite is dark to medium gray and has aphanitic to micrograined groundmass with abundant microphenocrysts of plagioclase (25 to 35 percent) and augite (5 to 10 percent). Andesitic mudflow deposits (map unit Taf) principally cap peaks and ridges in the northern part of the study area. Abundant bold outcrops commonly form vertical cliffs. Flows of andesite resembling that described above are locally present at or near the base of the mudflow unit, sug­ gesting that the two units are of the same age. The matrix of the mudflow deposits consists of very light brownish gray and unsorted andesite fragments; angular clasts of andesite of various colors and textures range from 0.1 to 1 in. in diameter, and some subangular to subrounded frag­ ments of the same materials are as large as 6 ft. Clasts of gneiss are locally present near the base. Some layers consist entirely of material no larger than very coarse sand, but most layers contain unsorted matrix-supported clasts of pebble to boulder size. Some layers seen in cliffs have larger clasts concentrated near their base or near their top; the latter situation suggests that the clasts were rafted during mudflow movement. Quaternary surficial deposits (map unit Qaf) surround the Cerbat Mountains. They consist principally of alluvial fan deposits and of alluvium in active stream channels. The general structure of the Cerbat Mountains is that of a large horst or uplifted block bounded by concealed faults lying in the valleys to the east and west. Several northwest-trending minor faults are present in the north part of the study area. The internal structure of the Precambrian rocks is complex and has not yet been studied. The Cerbat Mountains block is more or less truncated on both the north and south ends by sags in the horst; volcanic rocks of Tertiary age are exposed in these sags (Reynolds, 1988). The sources of the volcanic rocks in the study area have not been identified. However, the position of the thick andesitic mudflow deposits (fig. 2) indicates a source high on Mount Tipton itself. Additional mapping in adja­ cent areas is needed to find a source for the andesite and welded tuff low on the southwest flank of the mountains. Geochemistry A reconnaissance geochemical survey was conducted in the Mount Tipton Wilderness Study Area to evaluate it for indications of mineralization. Reconnaissance surveys are not designed to find individual deposits, rather they allow large areas to be subdivided into geochemical prov­ inces or mineralized districts. Rocks and minus-80-mesh stream sediments were selected as the sample media for this study. Stream sediments from 43 sites were collected, and heavy-mineral concentrates were prepared from each; rock samples from 26 sites were also collected. The stream-sediment samples were collected from active alluvium in the stream channels. Each sample was composited from several localities along a channel length of approximately 50 ft. The stream sediments were seived through an 80-mesh screen and pulverized to a fine powder before analysis. To prepare a heavy-mineral concentrate, stream sediment was seived through a 10-mesh screen and then panned until most of the quartz, feldspar, clays, and organic matter were removed. The remaining minerals of low density were removed with a heavy liquid (bromoform, specific gravity 2.8). The sample was then separated into magnetic, slightly magnetic, and nonmagnetic fractions by Mineral Resources of the Mount Tipton Wilderness Study Area, Arizona B7

use of an electromagnet. The nonmagnetic fraction of the concentrates was ground to a fine powder and analyzed. Stream sediments represent a composite of the rock and soil exposed upstream from the sample site. The heavy-mineral concentrate is representative of the heavymineral components of the rocks exposed in the drainage basin and could include ore-forming and ore-related miner­ als if mineralization has occurred within the drainage basin. Elements that are not easily detected in bulk stream sedi­ ments may appear in analyses of these concentrates. Rock samples were taken from mineralized, altered, and unaltered outcrops and from stream float. Samples of fresh, unaltered rock provide information on geochemical background concentrations. Altered or mineralized samples were collected to determine the suite of elements associated with observed alteration or mineralization. The rocks were crushed and pulverized to a fine powder before analysis. The heavy-mineral concentrates, stream sediments, and rocks were analyzed for 31 elements by semiquantitative, direct-current arc emission spectrography (Grimes and Marranzino, 1968; Crock and others, 1983). The rocks were also analyzed for arsenic, antimony, bismuth, cad­ mium, and zinc by atomic absorption (O'Leary and Viets, 1986) and for gold (Thompson and others, 1968) and mercury (Koirtyohann and Khalil, 1976). Analytical data for the Mount Tipton Wilderenss Study Area and a descrip­ tion of the sampling and analytical techniques were sup­ plied by J.H. Bullock, Jr. (written commun., 1988). Geochemical Results The analyses of the samples collected in the Mount Tipton Wilderness Study Area show a few elevated or anomalous concentrations. Most of the samples having anomalous concentrations are from the southernmost part of the study area; others are from widely scattered sites. Anomalous concentrations in the nonmagnetic fraction of the heavy-mineral concentrates include bismuth (100 to 1,000 parts per million, ppm), molybdenum (as much as 300 ppm), silver (as much as 20 ppm), tin (as much as 1,500 ppm), and tungsten (1,000 to 20,000 ppm). Three samples having anomalous tungsten and bismuth content are from the hornblende gneiss and amphibolite unit in the southernmost part of the study area. Other samples from widely scattered sites in the more common granitic gneiss have anomalous single-element concentrations of bismuth, molybdenum, silver, or tin. Some of these may be associ­ ated with the northwest-trending faults in the north half of the study area. The Wallapai (Chloride) mining district to the south includes some of the same rocks as those that underlie the study area. According to Schrader (1909), the suite of elements associated with the mineralization in this mining district includes silver, lead, gold, and copper. This suite of elements does not appear in anomalous concentrations in the Mount Tipton Wilderness Study Area; thus the geo­ chemical data obtained during this study do not support the extension of mineralization similar to that in the Wallapai district into the study area. Three samples from mineralized quartz veins in the southernmost part of the study area contain anomalous silver (maximum 2 ppm) and copper (maximum 2,000 ppm); two contain vanadium (maximum 30 ppm), and one contains 10 ppm each of cobalt and nickel. Numerous prospect pits in this area attest to the presence of minerali­ zation. Geophysics Three types of geophysical data (magnetic, radiomet­ ric, and gravity), from regional surveys in western Arizona, were compiled and examined to help assess of the mineral resource potential of the Mount Tipton Wilderness Study Area. Detailed aeromagnetic and radiometric data are available along profiles spaced about 1 mi apart. The sparse distribution of the gravity stations makes the data adequate for addressing the regional structural and tectonic setting of the study area but does not permit detailed state­ ments about mineral resource potential at the deposit scale. Aeromagnetic Data An aeromagnetic survey of the Kingman 1° by 2° quadrangle, California, Nevada, and Arizona, was flown in 1977 and compiled by Western Geophysical Company of America (1979) under contract to the U.S. Department of Energy as part of the National Uranium Resource Evalu­ ation (NURE) program. These data were subsequently merged with aeromagnetic surveys over adjacent areas by Mariano and Grauch (1988). Total-field magnetic data over the wilderness study area and surrounding parts of Arizona were collected along east-west flightlines spaced approximately 1 mi apart at a nominal height of 400 ft above the ground surface. Corrections were applied to the data to yield a residual magnetic field that primarily reflects the distribution of magnetization in the underlying rocks. The magnetic field over the Precambrian rocks of the Cerbat Mountains is characterized by elongate highs and lows that crudely define a northeast-trending magnetic grain similar to that produced by the basement rocks beneath the Colorado Plateau, adjacent to the east. Within the wilderness study area, one linear magnetic high more than 300 nanoteslas in amplitude and roughly 3 mi wide lies over the hornblende gneiss and amphibolite body (map unit p-Cha) that crops out in the southern part of the study area. This high indicates that concealed extensions of this body continue beneath the alluvium of the adjacent valley southwest of the study area boundary for more than 5 mi and also continue eastward along the south edge of the study area. A second major magnetic high within the study B8 Mineral Resources of Wilderness Study Areas: Black Mountains Region, Arizona

area, centered about 1 mi south of Mount Tipton, trends west and then north, straddling the west boundary of the study area. This high, 2 to 3 mi wide with an amplitude comparable to that of the first anomaly discussed above, lies over granitic gneiss (map unit p-Cgn). It is atypical of the magnetic field over most exposures of granitic gneiss within the study area and suggests the presence of a phase of granitic gneiss that is more magnetic, and probably more mafic, than normal. The Wallapai (Chloride) mining district (Dings, 1951) shows a magnetic feature that probably is indirectly related to the mineralization in the area. A broad, deep magnetic low over the Precambrian rocks is spatially well correlated with the district and includes more than 90 percent of the mines and prospects shown by Dings (1951). Only the mines of the Stockton Camp, located along the southeast edge of the district, are outside the low. The spatial dimen­ sions of the low and its location with respect to adjacent magnetic highs make it unlikely that this anomaly is a polarization effect of nearby magnetic bodies. Rather, it probably is caused by a magnetization that is significantly lower in the Precambrian rocks of the Wallapai mining district than in the surrounding Precambrian rocks. The lower magnetization may have resulted from alteration of the magnetic minerals by the mineralizing fluids that were the source of the deposits*in the mining district. Whatever the cause of the broad magnetic low, its close spatial correlation with the deposits of the Wallapai mining district indicates that it should be considered as a potential guide in assessing the mineral resource potential of the area surrounding the district. Because the low termi­ nates 1 to 2 mi south of the south boundary of the study area, this guide suggests that Wallapai district mineraliza­ tion does not continue north into the study area. Radiometric Data Radiometric data for the study area were collected at the same time and from the same aircraft as the magnetic data. Recordings were made of gamma-ray flux indicative of radioactive isotopes of potassium, thorium, and uranium. Only one anomaly indicative of thorium and having a count rate greater than one standard deviation above the mean was detected within the study area (Western Geophysical Company of America, Aero Service Division, 1979). The anomaly is about 1 mi wide and is centered at 35°29.5' N. and 114°12.9' W., just north of Putman Wash (fig. 2). A strong anomaly indicative of uranium was detected along a 3 mi-long east-west flightline segment extending west from the southwest end of Packsaddle Mountain. The anoma­ lous segment lies mostly south of the study area but is within 0.3 mi of the study area boundary. Minor anomalies indicative of uranium within the study area are scattered along a flightline located at 35°30.3' N., near the center of figure 2. Gravity Data Gravity data for the Mount Tipton Wilderness Study Area and vicinity include those shown by Mariano and others (1986) and an additional eight measurements made during 1987. Gravity data are sparse for the study area (3­ to 5-mi spacing) but are more numerous in the surrounding areas. Gravity values and total gravity relief in the study area are typical of those present over Precambrian rock exposed throughout the Cerbat Mountains. The total relief of about 15 milligals can be accounted for by density variations of about 0.2 grams per cubic centimeter (g/cm3) in the coun­ try rock, which extends to depths of 5,000 to 6,000 ft. Density contrasts of 0.2 g/cm3 or larger are characteristic of density differences between mafic and felsic Precambrian rocks in the region. Thus the sparse gravity data do not suggest any unusual density contrasts within the study area. Mineral and Energy Resource Potential The southernmost part of the study area (fig. 2) has low mineral resource potential, certainty level C, for gold, silver, copper, lead, zinc, and molybdenum in polymetallic veins such as those described by Cox (1986, model 22c). These commodities have had substantial production in the Wallapai (Chloride) mining district, in part from veins in hornblende gneiss similar to that exposed in the study area. The area of low mineral resource potential includes the outcrop area of the hornblende gneiss unit (p-Cha) and its extension as indicated by an aeromagnetic high. Mineral resource potential is suggested by anomalous concentra­ tions of silver, copper, vanadium, cobalt, and nickel in quartz veins and by anomalous silver concentrations in heavy-mineral concentrates. This area also has low mineral resource potential, certainty level C, for vein deposits of tungsten, as described by Cox and Bagby (1986, model 15a); this potential is suggested by the presence of anomalous concentrations of tungsten and bismuth in heavy-mineral concentrates. Fur­ thermore, this area has low resource potential, certainty level C, for uranium in vein deposits or pegmatites. This potential is suggested by the uranium anomaly shown by the airborne radiometric survey and by the presence of anomalous vanadium, a common associate of uranium. Two other small areas within the study area (fig. 2) have low mineral resource potential, certainty level C, for uranium and thorium, respectively, as suggested by the airborne radiometric anomalies. There are no known warm springs in the Cerbat Mountains and no volcanic or intrusive rocks of Quaternary age. However, data points from the map of Muffler (1979) suggest that the area has a heat flow of about 100 milliwatts per square meter, which is quite high. Basin-and-range faults, which are present in the area, can act as conduits for low-temperature water-circulation systems. Therefore the Mineral Resources of the Mount Tipton Wilderness Study Area, Arizona B9

entire study area has low potential, certainty level B, for geothermal energy resources. The study area is underlain by high-grade metamorphic rocks and some young volcanic and continental sedimen­ tary rocks. Because these are not good source rocks, the study area has no potential, certainty level D, for oil and gas resources (Ryder, 1983). REFERENCES CITED Almquist, C.L., 1988, Mineral investigation of the Mount Tipton Wilderness Study Area (AZ-020-012/042) and proposed additions, Mohave County, Arizona: U.S. Bureau of Mines Open-File Report MLA 9-88, 12 p. Beikman, H.M., Hinkle, M.E., Frieders, Twila, Marcus, S.M., and Edward, J.R., 1983, Mineral surveys by the Geological Sur­ vey and the Bureau of Mines of Bureau of Land Management Wilderness Study Areas: U.S. Geological Survey Circular 901, 28 p. Cox, D.P., 1986, Descriptive model of polymetallic veins, in Cox, D.P., and Singer, D.A., eds., Mineral deposits models: U.S. Geological Survey Bulletin 1693, p. 125. Cox, D.P., and Bagby, W.C., 1986, Descriptive model of W veins, in Cox D.P., and Singer, D.A., eds., Mineral deposits models: U.S. Geological Survey Bulletin 1693, p. 64. Crock, J.G., Lichte, F.E., and Briggs, P.H., 1983, Determination of elements in National Bureau of Standards geological refer­ ence material SRM 278 obsidian and SRM 668 basalt by induction coupled argon plasma-atomic emission spectrome­ try: Geostandards Newsletter, no. 7, p. 335-340. Dings, M.G., 1951, The Wallapai mining district, Cerbat Moun­ tains, Mohave County, Arizona: U.S. Geological Survey Bulletin 978-E, p. 123-163. Goudarzi, G.H., 1984, Guide to preparation of mineral survey reports on public lands: U.S. Geological Survey Open-File Report 84-787, 51 p. Grimes, D.J., and Marranzino, A.P., 1968, Direct-current arc and alternating-current spark emission spectrographic field meth­ ods for the semiquantitative analysis of geologic materials: U.S. Geological Survey Circular 591, 6 p. Keith, S.B., Gest, D.E., DeWitt, E.H., Toll, N.W., and Everson, B.A., 1983, Metallic mineral districts and production in Ari­ zona: Arizona Bureau of Geology and Mineral Technology Bulletin 194, 58 p. Koirtyohann, S.R., and Khalil, Moheb, 1976, Variables in deter­ mination of mercury by cold vapor atomic absorption: Ana­ lytical Chemistry, v. 48, p. 136-139. Mariano, John, and Grauch, V.J.S., 1988, Aeromagnetic maps of the Colorado River region including the Kingman, Needles, Salton Sea, and El Centro 1° x 2° quadrangles, California, Arizona, and Nevada: U.S. Geological Survey Miscellaneous Field Studies Map MF-2023; 5 sheets, scale 1:250,000; 1 sheet, scale 1:750,000. Mariano, John, Helferty, M.G., and Gage, T.B., 1986, Bouguer and isostatic residual gravity maps of the Colorado River region, including the Kingman, Needles, Salton Sea, and El Centro quadrangles: U.S. Geological Survey Open-File Report 86-347; 6 sheets, scale 1:250,000; 1 sheet, scale 1:750,000. McKelvey, V.E., 1972, Mineral resource estimates and public policy: American Scientist, v. 60, p. 32-40. Muffler, L.J.P., ed., 1979, Assessment of geothermal resources of the United States-1978: U.S. Circular 790, 163 p., 3 maps, scales 1:2,500,000, 1:5,000,000, 1:1,000,000. O'Leary, R.M., and Viets, J.G., 1986, Determination of antimony, arsenic, bismuth, cadmium, copper, lead, molybdenum, silver and zinc in geologic materials by atomic absorption spec­ trometry using a hydrochloric acid-hydrogen peroxide diges­ tion: Atomic Spectroscopy, v. 7, p. 4-8. Reynolds, S.J., 1988, Geologic map of Arizona: Arizona Geo­ logical Survey Map 26, scale 1:1,000,000. Ryder, R.T., 1983, Petroleum potential of wilderness lands in Arizona, in Miller, B.M., ed., Petroleum potential of wilder­ ness lands in the western United States: U.S. Geological Survey Circular 902-C, 22 p. Schrader, F.C., 1909, Mineral deposits of the Cerbat Range, Black Mountains, and Grand Wash Cliffs, Mohave County, Arizona: U.S. Geological Survey Bulletin 397, 226 p.. Thompson, C.E., Nakagawa, H.M., and Van Sickle, G.H., 1968, Rapid analysis for gold in geologic materials, in Geological Survey Research 1968: U.S. Geological Survey Professional Paper 600-B, p. B130-B132. U.S. Bureau of Land Management, 1983, Mount Tipton G-E-M resources area: Technical Report, AZ-04, 31 p. U.S. Bureau of Mines and U.S. Geological Survey, 1980, Prin­ ciples of a resource/reserve classification for minerals: U.S. Geological Survey Circular 831, 5 p. Western Geophysical Company of America, Aero Service Divi­ sion, 1979, Airborne gamma-ray spectrometer and magne­ tometer survey, Las Vegas quadrangle (Arizona, California, Nevada), Williams quadrangle (Arizona), Prescott quadrangle (Arizona), and Kingman quadrangle (Arizona, California, Nevada), final report: U.S. Department of Energy Open-File Report GJBX v. 2, variously paged. Wilson, E.D., Moore, R.T., and Cooper, J.R., 1969, Geologic map of Arizona: Arizona Bureau of Mines and U.S. Geological Survey, scale 1:500,000. B10 Mineral Resources of Wilderness Study Areas: Black Mountains Region, Arizona

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 accumulation, where data support mineral-deposit models indicating presence of resources, and where evidence indicates that mineral concentration has taken place. Assignment of high resource potential to an area requires some positive knowledge that mineral-forming processes have been active in at least part of the area. M MODERATE mineral resource potential is assigned to areas where geologic, geochemical, and geophysical characteristics indicate a geologic environment favorable for resource occurrence, where interpretations of data indicate reasonable likelihood for resource accumulation, and (or) where an application of mineral-deposit models indicates favorable ground for the specified of deposits. 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. UV 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. Available information gives a good indication of the level of mineral resource potential. D Available information clearly defines the level of mineral resource potential. A B D A U/A H/B H/C H/D HIGH POTENTIAL HIGH POTENTIAL HIGH POTENTIAL LEVE LO FRESOURCEPOTENT! AL UNKNOWN POTENTIAL M/13 MODERATE POTENTIAL L/B LOW POTENTIAL M/C MODERATE POTENTIAL L/C LOW POTENTIAL M/D MODERATE POTENTIAL LID LOW POTENTIAL N/D NO POTENTIAL LEVEL OF CERTAINTY Abstracted with minor modifications from: Taylor, R.B., and Steven, T.A., 1983, Definition of mineral resource potential: Economic Geology, v. 78, no. 6, p. 1268-1270. Taylor, R.B., Stoneman, R.J., and Marsh, S.P., 1984, An assessment of the mineral resource potential of the San Isabel National Forest, south-central Colorado: U.S. Geological Survey Bulletin 1638, p. 40-42. Goudarzi, G.H., compiler, 1984, Guide to preparation of mineral survey reports on public lands: U.S. Geological Survey Open-File Report 84-0787, p. 7, 8. B12 Mineral Resources of Wilderness Study Areas: Black Mountains Region Arizona

RESOURCE/RESERVE CLASSIFICATION IDENTIFIED RESOURCES UNDISCOVERED RESOURCES Demonstrated Probability Range Inferred Measured Indicated Hypothetical Speculative ECONOMIC Reserves Inferred Reserves

MARGINALLY ECONOMIC Mar l Marginal Reserves Inferred Marginal Reserves —

SUBDemonstrated Subeconomic Inferred Subeconomic ECONOMIC Resources Resources 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 Mount Tipton Wilderness Study Area, Arizona B13

GEOLOGIC TIME CHART Terms and boundary ages used by the U.S. Geological Survey in this report EON ERA PERIOD Quaternary Neogene Cenozoic Subperiod Tertiary Paleogene Subperiod Cretaceous Mesozoic Jurassic Triassic Phanerozoic Permian Pennsylvanian Carboniferous Periods Mississippian Devonian Paleozoic Silurian Ordovician Cambrian Late Proterozoic Proterozoic Middle Proterozoic Early Proterozoic Late Archean Middle Archean rc ean Early Archean (3800?) pre-Archean2 'Rocks older than 570 Ma also called Precambrian, a time term without specific rank. 2informal time term without specific rank. EPOCH Holocene Pleistocene Pliocene Miocene Oligocene Eocene Paleocene Late Early Late Middle Early Late Middle Early Late Early Late Middle Early Late Early Late Middle Early Late Middle Early Late Middle Early Late Middle Early AGE ESTIMATES OF BOUNDARIES IN MILLION YEARS (Ma) B14V Mineral Resources of Wilderness Study Areas: Black Mountains Region, Arizona

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1V?IiN ti m m H N in o cro. rT

Plates & figures from the original