Mineral Resources of the Baboquivari Peak 

and Coyote Mountains Wilderness Study Areas, 

Pima County, Arizona 

ARIZONA 
Chapter E 

Mineral Resources of the 

Baboquivari Peak and Coyote Mountains 

Wilderness Study Areas, · 

Pima County, Arizona 

By GARY A. NOWLAN, GORDON B. HAXEL, 

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

DENNY V. DIVELEY-WHITE 

U.S. Geological Survey 

JOHN R. McDONNELL, JR. and WILLIAM LUNDBY 

U.S. Bureau of Mines 

U.S. GEOLOGICAL SURVEY BULLETIN 1702 

MINERAL RESOURCES OF WILDERNESS STUDY AREAS: 

SOUTHWESTERN AND SOUTH-CENTRAL 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 Baboquivari Peak and Coyote Mountains Wilderness 

Study Areas, Pima County, Arizona I by Gary A. Nowlan ... [et al.]. 

p. em. - (U.S. Geological Survey bulletin ; 1702-E) 

Bibliography: p. 

Supt. of Docs. no.: I 19.3:1702-E 

1. Mines and mineral resources-Arizona-Baboquivari Peak Wilderness. 

2. Mines and mineral resources-Arizona-Coyote Mountains Wilderness. ' 

3. Baboquivari Peak Wilderness (Ariz.) 4. Coyote Mountains Wilderness (Ariz.) 

I. Nowlan, G.A. II. Series. 

QE75.B9 no. 1702-E 557.3 s-dc20 89-600057 

[TN24.A6] [553 1.09791 '77] 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 L"le 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 mineral surveys of the Baboquivari Peak 

(AZ-020-203B) and Coyote Mountains (AZ-020-202) Wilderness Study Areas, Pima 

County, Arizona. 
CONTENTS 

Summary El 

Abstract El 

Character and setting El 

Identified mineral resources E3 

Mineral resource potential of the Baboquivari Peak Wilderness Study Area E3 

Mineral resource potential of the Coyote Mountains Wilderness Study Area E3 

Introduction ES 

Location and physiography ES 

Previous and present investigations E7 

Acknowledgments E8 

Appraisal of identified resources E8 

Baboquivari Peak Wilderness Study Area E8 

Mining history E8 

Mineral appraisal E9 

Coyote Mountains Wilderness Study Area E9 

Mining history E9 -

Mineral appraisal Ell 

Assessment of mineral resource potential El3 

Geology El3 

Geologic framework of the Baboquivari Mountains El3 

Geology of the Baboquivari Peak Wilderness Study Area El3 

Geology of the Coyote Mountains Wilderness Study Area El7 

Geochemistry El8 

Geochemistry of the Baboquivari Peak Wilderness Study Area El8 

Geochemistry of the Coyote Mountains Wilderness Study Area El9 

Geophysics El9 

Aeromagnetics El9 

Aerial gamma-ray spectrometry E20 

Mineral resource potential of the Baboquivari Peak Wilderness Study Area El9 

Polymetallic vein deposits E21 

Beryllium-, bismuth-, and thorium-bearing pegmatites E21 

Paleoplacer gold-silver deposits E21 

Gold-silver deposits associated with an inferred porphyry 

molybdenum deposit E22 

Other commodities E22 

Mineral resource potential of the Coyote Mountains Wilderness Study Area E22 

Copper skarn and polymetallic replacement deposits E22 

Mineralized pegmatites E23 

Gold deposits associated with detachment faults E23 

Other commodities E24 

References cited E24 

Appendixes 

Definition of levels of mineral resource potential and certainty of assessment E28 

Resource/reserve classification E29 

Geologic time chart E30 

FIGURES 

1. Index map showing location of the Baboquivari Peak and Coyote Mountains Wilderness 

Study Areas, Pima County, Arizona E2 

2. Map showing mineral resource potential and generalized geology of the Baboquivari 

Peak Wilderness Study Area, Pima County, Arizona E4 

Contents V 
3. Map showing mineral resource potential and generalized geology of the Coyote Mountains Wilderness Study Area, Pima County, Arizona E6 

4. Map showing location of mining and exploration activities, drainage basins, sampling 

sites, and elements present in anomalous concentrations in and near the Baboquivari 

Peak Wilderness Study Area, Pima County, Arizona ElO 

5. Map showing location of mining and exploration activities, drainage basins, sampling 

sites, and elements present in anomalous concentrations in and near the Coyote Mountains Wilderness Study Area, Pima County, Arizona E14 

TABLES 

1. Mines, prospects, claims, and mineral occurrences in and near the Baboquivari Peak 

Wilderness Study Area El2 

2. Mines, prospects, and claims in and near the Coyote Mountains Wilderness Study 

Area E15 

VI Contents 
Mineral Resources of the 

Baboquivari Peak and Coyote Mountains 

Wilderness Study Areas, 

Pima County, Arizona 

By Gary A. Nowlan, Gordon B. Haxel, William F. Hanna, 

James A. Pitkin, and Denny V. Diveley-White 

U.S. Geological Survey 

John R. McDonnell, Jr. and William Lundby 

U.S. Bureau of Mines 

SUMMARY 

Abstract 

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

the 2,065 acres of the Baboquivari Peak Wilderness Study 

Area (AZ-020-2038) and the 5,080 acres of the Coyote 

Mountains Wilderness Study Area (AZ-020-202) were evaluated for mineral resources (known) and mineral resource 

potential (undiscovered). The Baboquivari Peak and Coyote 

Mountains Wilderness Study Areas are located in the Baboquivari Mountains in central Pima County, Arizona. Field 

work for this report was conducted between 1978 and 1987. 

The Baboquivari Peak Wilderness Study Area is underlain by jurassic supracrustal (including granitoid) rocks intruded by middle Tertiary rhyolite dikes (see geologic time 

chart in appendixes). One gold-silver occurrence in the 

Baboquivari Peak Wilderness Study Area has been reported. 

The entire Baboquivari Peak Wilderness Study Area has high 

potential for resources of gold, silver, copper, lead, zinc, 

barium, bismuth, manganese, molybdenum, or tungsten in 

polymetallic veins spatially associated with felsic to intermediate intrusions. The northern part of the Baboquivari Peak 

Wilderness Study Area has low potential for resources of 

beryllium and bismuth in pegmatites or quartz veins and the 

entire wilderness study area has low potential for thorium 

resources in pegmatites. The entire Baboquivari Peak Wilderness Study Area has low potential for gold and silver resources in paleoplacer deposits. The entire Baboquivari Peak 

Wilderness Study Area has low potential for gold and silver 

resources in veins or disseminated deposits associated with 

the outer halo of an inferred porphyry molybdenum deposit, 

Manuscript approved for publication, December 28, 1988. 

and the southern part of the wilderness study area has low 

potential for molybdenum resources based on that inferred 

deposit. 

The Coyote Mountains Wilderness Study Area is underlain by Paleozoic metasedimentary rocks, jurassic granitoids, 

and early Tertiary granite. About 20 mining claims are located in the Coyote Mountains Wilderness Study Area. Parts 

of the Coyote Mountains Wilderness Study Area that are 

underl~in by Paleozoic metasedimentary rocks have high 

f?Otentlal for resources of copper, tungsten, gold, silver, 

molybdenum, and zinc in skarn and polymetallic replacement deposits. The entire Coyote Mountains Wilderness 

Study Area has low potential for resources of thorium, niobium, uranium, and rare-earth elements, such as lanthanum 

and yttrium, in pegmatites. The northeastern part of the 

Coyote Mountains Wilderness Study Area has moderate potential for gold resources associated with a detachment fault. 

The potential for oil, gas, geothermal energy, and industrial minerals is low in both wilderness study areas. 

Character and Setting 

The Baboquivari Peak and Coyote Mountains Wilderness Study Areas are located in the central and northern 

part, respectively, of the Baboquivari Mountains in central 

Pima County, Arizona. Baboquivari Peak forms the southwestern comer of the Baboquivari Peak Wilderness Study 

Area (fig. 1). The Coyote Mountains Wi_ldemess Study 

Area is several miles east of Kitt Peak National Observatory (fig. 1). 

Major lithologic units in the Baboquivari Peak Wilderness Study Area are Early Jurassic sedimentary, volcanic, 

Baboquivari Peak and Coyote Mountains Wilderness Study Areas, Pima County, Arizona El 
0 

APPROXIMATE BOUNDARY 

OF COYOTE MOUNTAINS 

WILDERNESS STUDY AREA 

(AZ-020-202) 

Tohono O'Odham 

(Pap ago) 

Indian 

Reservation 

Chutum Vaya 

5 10 MILES 

~--·-·---~·-·-·-·--~ 

I 

I 

I 

I 

i 

.-·--

1 

I 

I 

·-·-·-·-

Figure 1. Index map showing location .of the Baboquivari Peak and Coyote Mountains Wilderness Study Areas, Pima County, 

Arizona. 

E2 Mineral Resourc~ of Wilderhess Study Areas: Southwestern and South-Central Arizona 
and hypabyssal rocks of the Pitoikam and Mulberry Wash 

Volcanic Formations; the Late Jurassic perthite granite of 

Baboquivari Peak; and the middle Tertiary rhyolite of 

Allison Camp. The Early Jurassic supracrustal rocks form 

a west-dipping homocline. The Mulberry Wash Volcanic 

Formation is intruded by the perthite granite of Baboquivari 

Peak. The rhyolite of Allison Camp intrudes the supracrustal rocks and the perthite granite as a rectilinear network of 

northwest- and northeast-trending dikes. 

Major lithologic units in the Coyote Mountains Wilderness Study Area are Paleozoic metasedimentary rocks; 

Middle to Late Jurassic diorite, granodiorite, and granite 

units; and the early Tertiary (58 Ma, million years) Pan Tak 

Granite. The Pan Tak Granite underlies most of the Coyote 

Mountains Wilderness Study Area and is a moderately 

alumina-rich leucogranite. The older rocks form pendants 

within the Pan Tak Granite. Pegmatite dikes are abundant 

within the Pan Tak pluton and its wall rocks. A westnorthwest-trending detachment fault is present on the north 

side of the Coyote Mountains. 

Identified Mineral Resources 

No identified mineral or energy resources are present 

within the Baboquivari Peak Wilderness Study Area, although several base-metal (copper, lead, zinc) and precious-metal (gold, silver) commodities have been mined or 

prospected nearby. 

About 700 short tons of copper-silver-gold ore were 

shipped between 1909 and 1951 from the Bonanza mine 

area, which is within the boundary of the Coyote Mountains Wilderness Study Area. The ore, localized along 

limestone-granite contacts, averaged 10 percent copper; 1.7 

ttoy oz silver/st (short ton), and 0.03 ttoy oz gold/st. 

Drilling records and U.S. Bureau of Mines sampling identified subeconomic inferred resources totaling 66,500 short 

tons averaging in excess of 5 percent copper, 1.5 troy oz 

silver/st. and 0.15 percent tungsten trioxide near the old 

workings. Resources of oil, gas, geothermal energy, and 

industrial minerals have not been identified. 

Mineral Resource Potential of the 

Baboquivari Peak Wilderness Study Area 

The entire Baboquivari Peak Wilderness Study Area 

has high potential for resources of gold, silver, copper, 

lead, zinc, barium, bismuth, manganese, molybdenum, or 

tungsten in polymetallic veins (fig. 2). Favorable criteria 

include presence of fracturing, middle Tertiary silicic dikes, 

nearby vein mineralization, and geochemical anomalies. 

The northern part of the Baboquivari Peak Wilderness 

Study Area has low potential for beryllium and bismuth 

resources in pegmatites and quartz veins; the entire area has 

low potential for thorium resources in pegmatites (fig. 2). 

Beryl- and bismuth-bearing pegmatites, of Jurassic(?) age, 

are present 2 mi east of the Baboquivari Peak Wilderness 

Study Area. The Late Jurassic granite to which these 

pegmatites are probably related does not extend into the 

wilderness study area, but the possibility of isolated beryland bismuth-bearing pegmatite bodies within the wilderness study area cannot be precluded. 

The Baboquivari Peak Wilderness Study Area has low 

potential for gold and silver resources in paleoplacer deposits in parts of the wilderness study area that are underlain 

by Early Jurassic siliciclastic strata (fig. 2). Favorable criteria in the study area include anomalous concentrations of 

gold and silver in panned-concentrate samples derived from 

stream sediments, visible gold in panned-concentrate 

samples, and favorable geology. 

The Baboquivari Peak Wilderness Study Area has low 

potential for gold and silver resources in veins or disseminated deposits associated with the outer halo of an inferred 

porphyry molybdenum deposit The southern part has low 

potential for molybdenum resources in the inferred porphyry molybdenum deposit that may be located near the 

south end of the wilderness study area. Favorable criteria 

in or near the wilderness study area include alteration, 

faults, middle Tertiary silicic dikes, felsic intrusive rocks, 

nearby polymetallic vein deposits, and geochemical anomalies. 

The Baboquivari Peak Wilderness Study Area has low 

potential for resources of oil, gas, geothermal energy, and 

industrial minerals. Appropriate reservoir rocks for oil and 

gas are not present. No thermal springs or wells occur in 

the wilderness study area. Industrial minerals (sand and 

gravel, in this case) are present in only small quantities. 

Mineral Resource Potential of the 

Coyote Mountains Wilderness Study Area 

The part of the Coyote Mountains Wilderness Study 

Area that ·is underlain by Paleozoic metasedimentary rocks 

has high potential for resources of copper, tungsten, gold, 

silver, molybdenum, and zinc in skarn and polymetallic 

replacement deposits (fig. 3). Favorable criteria include 

known occurrences of this type, the presence of calcareous 

metasedimentary rocks locally altered to skarn, and geochemical anomalies. 

The entire Coyote Mountains Wilderness Study Area 

has low potential for thorium, niobium, uranium, and rareearth elements (such as lanthanum and yttrium) resources 

in mineralized pegmatites. Simple pegmatites, which are 

associated with an early tertiary alumina-rich leucogranite, 

are abundant in the wilderness study area. Although no 

complex pegmatites are known, some stream-sediment 

samples contain anomalous concentrations of thorium, 

niobium, lanthanum, and yttrium and a uranium-bearing 

pegmatite is present east of the wilderness study area. 

The northeastern part of the Coyote Mountains Wilderness Study Area has moderate potential for gold resources 

associated with a middle Tertiary detachment fault. Some 

Baboquivari Peak and Coyote Mountains Wilderness Study Areas, Pima County, Arizona E3 
Figure 2. Mineral resource potential and generalized geology of the Baboquivari Peak Wilderness Study Area, Pima 

County, Arizona. Base from U.S. Geological Survey, 1979, Baboquivari Peak and Mildred Peak quadrangles. 

Contour interval 20 and 40 ft. 

E4 Mineral Resources of Wilderness Study Areas: Southwestern and South-Central Arizona 
panned-concentrate" samples derived from stream sediments 

·have anomalous concentrations of gold. 

The Coyote Mountains Wilderness Study Area has low 

potential for resources of oil, gas, geothermal energy, and 

EXPLANATION 

1:~:~:~:~:~:~:~:~:~:~1 Area with high mineral resource potential (H) 

r::J Area with low mineral resource potential (L) 

Levels of certainty of assessment 

B Data only suggest level of potential 

C Data give good indication of level of potential 

<;:;ommodities 

Ag Silver 

Au Gold 

Ba Barium 

Be Beryllium 

Bi Bismuth 

Cu Copper 

Geo Geothermal 

I Industrial sand and gravel, limestone 

Mn Manganese 

Mo Molybdenum 

0, G Oil and gas 

Pb Lead 

Th Thorium 

Zn Zinc 

[ ] Deposit type 

1 Polymetallic veins 

2 Pegmatites 

3 Paleoplacer gold-silver 

4 Gold-silver, disseminated or in veins associated 

with porphyry molybdenum 

5 Porphyry molybdenum 

Description of map units 

QTg Gravel and alluvium (Quaternary and late Tertiary) 

Tac Rhyolite of Allison Camp (middle Tertiary)-

Intrusive rhyolite body 

Tgd Hornblende granodiorite (Tertiary) 

Ta Andesitic and dacitic flows and intrusions (Tertiary) 

Tc Conglomerate (Tertiary) 

Jb Perthite granite of Baboquivari Peak (Late Jurassic) 

Jpk Granite of Pavo Kug Wash (Late Jurassic) 

Jk Granodiorite of Kitt Peak (Middle Jurassic) 

Jt Rhyodacite porphyry of Tinaja Spring (Early 

Jurassic) 

Jcs Chiuli Shaik Formation (Early Jurassic) 

Jm Mulberry Wash Volcanic Formation (Early Jurassic) 

Jp Pitoikam Formation (Early Jurassic) 

Ja Ali Molina Formation (Early Jurassic) 

Contact 

---- High-angle fault-Dashed where approximate or 

concealed 

----- Dike of intrusive rhyolite of Allison Camp (unit 

Tac)-Approximately located 

Figure 2. Continued. 

industrial minerals. Appropriate reservoir rocks for oil and 

gas are absent. Thermal springs or wells do not occur in 

the wilderness study area. Only small quantities of industrial minerals (sand, gravel, and limestone, in this case) are 

present. 

INTRODUCTION 

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

of Land Management and is a joint 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). 

Studies by the U.S. Geological Survey are designed to 

provide a reasonable scientific basis for assessing the potential for undiscovered mineral resources by determining 

geologic units and structures, possible environments of 

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

assessment methodology and terminology as they apply to 

these surveys were discussed by Goudarzi (1984). See 

appendixes for the definition of levels of mineral resource 

potential, certainty of assessment, and classification of 

identified resources. 

Throughout this report "study area" refers to either the 

Baboquivari Peak Wilderness Study Area or the Coyote 

Mountains Wilderness Study Area or both and will include 

sampled areas outside but adjacent to the wilderness study 

areas. The term "wilderness study area" refers to terrain 

only within the boundaries of one or the other of the two 

wilderness study areas. In general, references to the Baboquivari Mountains will include the Coyote Mountains 

and Quinlan Mountains. 

Location and Physiography 

The Baboquivari Peak (AZ-020--203B) and Coyote 

Mountains (AZ-020-202) Wilderness Study Areas are 

located in Pima County, Arizona, approximately 45 and 35 

mi, respectively, southwest of Tucson. Both wilderness 

study areas are within the Baboquivari Mountains, a chain 

of mountains that stretches continuously for 37 mi from the 

Sierra de Pozo Verde in northernmost Sonora ~orth through 

the Quinlan Mountains to the Coyote Mountains (fig. 1). 

Kitt Peak National Observatory is situated atop the Quinlan 

Mountains, about 5 mi southwest of the Coyote Mountains 

Wilderness Study Area. 

Baboquivari Peak and Coyote Mountains Wilderness Study Areas, Pima County, Arizona ES 
32° 

2' 

30" 

31 ° 

57' 

30" 

OTg 

ll 

Tc 

111 °32'30" 

' Jv 

/ 

111 °30'00" 

__ :::...:.---

OTg 

£~/-

A'--.~ 

\. 

\ 

QTg 

Figure 3. Mineral resource potential and generalized geology of the Coyote Mountains Wilderness Study Area, Pima County, 

Arizona. Base from U.S. Geological Survey, 1979, Kilt Peak, Palo Alto Ranch, Pan Tak, and San Pedro quadrangles. Contour 

interval 1 0, 20, and 40 ft 

E6 Mineral Resources of Wilderness Study Areas: Southwestern and South-Central Arizona 
The Baboquivari Peak Wilderness Study Area is an 

irregular, north-south-elongate area of about 2,065 acres on 

the eastern slope of the Baboquivari Mountains. The west 

boundary of the study area is the crest of the range and is 

coincident with the boundary of the Tohono O'Odham 

(fonnerly Papago) Indian Reservation. The wilderness 

study area extends from Baboquivari Peak and the upper 

drainage area of Thomas Canyon Wash north 6 mi to 

uppermost Contreras Wash. Most of the terrain within the 

study area is rugged, with rocky slopes, ridges, and canyons. The summit of Baboquivari Peak (7 ,734 ft) is the 

highest point; the lowest elevations are about 5,200 ft 

EXPLANATION 

~:~:t~:~:t~:l Area with high mineral resource potential (H) 

f:::;::::;:::;::;::: l Area with moderate mineral resource potential (M) 

c:J Area with low mineral resource potential (L) 

Levels of certainty of assessment 

8 Data only suggest level of potential 

C Data give good indication of level of potential 

Au 

Ag 

Cu 

La, Y 

Mo 

Nb 

u 

[ 1 

Commodities 

Gold 

Silver 

Copper 

Lanthanum and 

yttrium 

Molybdenum 

Niobium 

Uranium 

Deposit type 

Th 

w 

Zn 

I 

O,G 

Geo 

Thorium 

Tungsten 

Zinc 

Industrial sand and 

gravel, limestone 

Oil and gas 

Geothermal 

1 Copper skarn and polymetallic veins 

2 Pegmatites 

3 Gold deposits associated with detachment faults 

Description of map units 

QTg 

Tc 

Tp 

Kr 

Ks 

Jv 

Jpk 

Jk 

Jn 

Pzq 

Pzc 

~lllllllllllltt,. 

:;,,,,,,,,,,,,,,~ 

Gravel and alluvium (Quaternary and late Tertiary) 

Conglomerate (late Tertiary) 

Pan Tak Gr~-llte (early Tertiary) 

Roskruge Volcanics (Cretaceous) 

Sand Wells Formation (Cretaceous?) 

Volcanic rocks (Jurassic) 

Granite of Pavo Kug Wash (Late Jurassic) 

Granodiorite of Kitt Peak (Middle Jurassic) 

Diorite of Nawt Vaya (Middle Jurassic) 

Quartzite (Paleozoic) 

Calc-silicate schist (Paleozoic) 

Contact 

Fault-Dashed where approximate or concealed 

Area of penetrative mylonitic foliation and lineation 

in Pan Tak Granite 

Figure 3. Continued. 

Primary access to the study area is from Arizona Highway 

286 in Altar Valley on the east via dirt roads and trails up 

Thomas, Brown, Sabino, and Contreras Washes. The study 

area is also accessible from the west through Fresnal, 

Sycamore, and Baboquivari Washes within the Tohono 

O'Odham Indian Reservation. 

The Coyote Mountains Wilderness Study Area includes 5,080 acres encompassing most of the higher parts 

of the rugged Coyote Mountains. The inverted L-shaped 

configuration of the wilderness study area approximates the 

two main ridges, one north-south and the other east-west, 

that comprise the Coyote Mountains. Each limb of the L 

is about 4 mi long. The highest point within the wilderness 

study area is 6,529 ft at the summit of Coyote Peak. 

Terrain within the wilderness study area consists of rugged 

and steep slopes, cliffs, narrow ridges, and steep canyons; 

the central part includes a number of steep-sided granitic 

domes. Access to much of the study area is limited due to 

the steep topography and some areas can be reached only 

by using technical climbing aids. The three principal 

means of access to the study area are from the east via dirt 

roads up Mendoza Wash, from the north via a dirt road and 

trail that connect with Arizona Highway 86 through the 

village of Nawt Vaya, and from the west via dirt roads from 

the village of Pan Tak or Arizona Highway 386 (the road 

to Kitt Peak National Observatory). The west and north 

boundaries of the wilderness study area are coincident with 

the boundary of the Tohono O'Odham Indian Reservation 

and access routes from the north and west cross the reservation. From the northern access route, a hiking trail 

through the study area leads to the summit of the Coyote 

Mountains. 

Previous and Present Investigations 

The earliest detailed geologic investigations in or adjacent to the Baboquivari Peak and Coyote Mountains Wilderness Study Areas were University of Arizona thesis 

studies by Wargo (1954), Kurtz (1955), Clark (1956), 

Wargo and Kurtz (1956), Donald (1959), Balla (1962), Fair 

(1965), Min (1965), and Carrigan (1971). Only the studies 

by Donald (1959), Balla (1962), and Carrigan (1971) deal 

specifically with mineral resources: beryllium occurrences 

near the Baboquivari Peak Wilderness Study Area and 

copper occurrences within the Coyote Mountains Wilderness Study Area. Broad reconnaissance geologic mapping 

of most of the northern part of the Baboquivari Mountains 

in the 1950's by L.A. Heindl of the U.S. Geological Survey 

was published only as a figure in a field trip guide (Galbraith and others, 1959, fig. 57). The northern part of the 

Coyote Mountains is within the area mapped by Keith 

(1976). Heindl and Fair (1965) defmed several Mesozoic 

(Lower Jurassic) stratigraphic units in the Fresnal Canyon 

area, west of the Baboquivari Peak Wilderness Study Area. 

Baboquivari Peak and Coyote Mountains Wilderness Study Areas, Pima County, Arizona E7 
A mineralized area 2 mi south of the Baboquivari Peak 

Wilderness Study Area was studied by Seaman (1983). 

Tertiary deformation in the northern Coyote Mountains and 

in the Sierra de Pozo Verde was studied by Davis (1980), -

Gardulski (1980), and Davis and others (1987). Mineral 

occurrences within the Baboquivari Peak and Coyote 

Mountains Wilderness Study Areas are included in county 

summaries by Keith (1974) and Schnabel and others 

(1986). 

The entire Baboquivari Mountains north of the Sonoran border were mapped from 1978 to 1980 (Haxel and 

others, 1980a, 1982) as part of a mineral resource assessment of the Tohono O'Odham Indian Reservation. The 

geologic mapping was accompanied by uranium/lead isotopic geochronology (Wright and Haxel, 1982; Wright and _ 

others, 1981; Haxel and others, 1980a, b; Tosdal and others, 1989). Additional geologic studies within or adjacent 

to the Baboquivari Peak and Coyole Mountains Wilderness 

Study Areas were conducted in 1986 and 1987. Samples 

from the Coyote Mountains were included in isotopic studies by Solomon and Taylor (1981) and Farmer and Depaolo 

(1984) . A regional paleomagnetic study (Cohen, 1981; 

Cohen and others, 1981) included Lower Jurassic strata in 

an area a few miles northwest of the Baboquivari Peak 

Wilderness Study Area. Some of the Tertiary base- and 

precious-metal fissure veins near the Baboquivari Peak 

Wilderness Study Area were studied by Tosdal (1981) and 

Tosdal and Briskey (1981). Kluth (1980) evaluated the 

"uranium favorability" of the Coyote Mountains (see also 

Reynolds, 1980). The Sierra de Pozo Verde in northernmost Sonora was mapped by Haxel in 1982 (Haxel and 

others, 1984, fig. 3). Regional geologic or tectonic overviews that include the Baboquivari Mountains chain are 

provided by Haxel and others (1980b, 1984), and Tosdal 

and others (1989). 

Reconnaissance geochemical studies of the Baboquivari Peak and Coyote Mountains Wilderness Study 

Areas were undertaken in 1986 and 1987 (Adrian and 

others, 1987, 1988; Nowlan, 1988). Stream-sediment 

samples were collected within- or down drainage from the 

wilderness study areas. Several samples of mineralized 

rock were collected from dumps and adits in the Coyote 

Mountains Wilderness Study Area. The samples were 

analyzed for as- many as 32 elements by semiquantitative 

emission spectrography, atomic-absorption spectroscopy, 

neutron-activation analysis, and inductively coupled plasma 

spectroscopy. Analyses of water from springs and dug 

wells on and near the Tohono O'Odham Indian Reservation 

are tabulated by Ficklin and others (1978, 1980). Samples 

of unmineralized and unaltered granite from the Coyote 

Mountains were analyzed as part of a regional study of the 

geochemistry of early Tertiary peraluminous leucogranites 

(Haxel, 1987). 

Both wilderness study areas are ~overed by regional 

gravity (Lysonski and others, 1980; Defense Mapping 

Agency Aerospace Center, 1974, 1975) and by aeromagnetic surveys at 1:250,000 scale (U.S. Geological Survey, 

1980). The sparseness of gravity control limits definition 

of Bouguer gravity anomalies to wavelengths far longer 

than those useful for inferring sources at the scale of the 

study. However, the magnetic data points are sufficiently 

closely spaced to define sources of 1 miZ or larger. The 

abundance of radioelements in the Baboquivari Peak Wilderness Study Area was estimated from aerial gamma-ray 

spectrometric data (U.S. Department of Energy, 1978a, 

1978b). 

Mineral investigations of the Baboquivari Peak and 

Coyote Mountains Wilderness Study Areas by the U.S. 

Bureau of Mines were carried out in 1985 and 1986 

(McDonnell, 1986; Lundby, 1987). The investigations 

included a review of literature concerning mineral resources and mining activity; field examination of mines, 

- prospects, and mineral occurrences in and near the wilderness study areas; mapping and sampling of mines and 

prospects; and collection of stream-sediment samples. 

Information about mining claims, oil and gas leases, and 

land status was obtained from the U.S. Bureau of Land 

Management and from Pima County records. Minerals 

information and production data were obtained from U.S. 

Bureau of Mines files and other sources. 

Acknowledgments 

R.G. Eppinger performed the mineralogic examination 

of panned-concentrate samples. We thank the following 

ranchers and land owners for access to their property: 

Roger Adams (Santa Margarita Ranch), Ray Harm, Ross 

Humphreys, Donald Janson, John King (Anvil Ranch), and 

Robert Miller (Elkhorn Ranch). 

APPRAISAL OF IDENTIFIED RESOURCES 

By John R. McDonnell, Jr., and William Lundby 

U.S. Bureau of Mines 

Baboquivari Peak Wilderness Study Area 

Mining History 

The Baboquivari Peak Wilderness Study Area is within 

the Baboquivari mining district, which extends about 33 mi 

northward from Mexico and includes the Baboquivari 

Mountains. No mining activity has been recorded within 

the wilderness study area, but intermittent, generally smallscale mining and limited prospecting have occurred in the 

surrounding area (fig. 4). In 1985, U.S. Bureau of Land 

Management records showed two patented mining claims 

about 2.5 mi south of the wilderness study area and one 

E8 Mineral Resources of Wilderness Study Areas: Southwestern and South-Central Arizona 
unpatented claim less than 1 mi east of its northern tip. The 

establishment of the Tohono O'Odham Indian Reservation 

in 1955 closed the western part of the district to mineral 

entry under rules of the 1872 General Mining Law. 

Mining in the Baboquivari district began in the late 

1800's at the Allison and Jupiter mines (Nos. 4 and 7, fig. 

4). Keith (1974, p. 14-17) summarized the geology and 

history of the district, and estimated a total production of 

57,000 short tons (st) of ore containing about 14,000 troy 

oz gold, 173,000 troy oz silver, 122 st copper, 12 st lead, 

a small amount of zinc, 24 st of tungsten concentrates, and 

200 long tons of manganese ore. A small amount of placer 

gold was also recovered. 

Most of the nearby mining activity was either west to 

northwest or south to southwest of the wilderness study 

area; activity within 3.5 mi of the boundary is summarized 

in table 1 and figure 4. Two groups of tungsten deposits, 

one 9-12 mi northwest of the study area near San Juan 

Spring and the other 6-8 mi southwest of the study area 

near Chutum Vaya (fig. 1), are not shown but have contributed to the total production reported above. 

Mineral Appraisal 

No mineral deposits or occurrences were found within 

the Baboquivari Peak Wilderness Study Area as a result of 

U.S. Bureau of Mines investigations, although Cruver and 

others (1982) and Stipp and others (1967) reported a goldsilver occurrence near the center of the wilderness study 

area. U.S. Bureau of Mines personnel traversed the area, 

but could find no gold-silver occurrence. Two streamsediment samples were collected outside the wilderness 

study area from drainages in upper Brown Canyon where 

the occurrence was thought to be located; one of the 

samples assayed 42 parts per billion (ppb) gold. The 

samples were also assayed for silver and tungsten but both 

samples had concentrations below the lower detection 

limits (silver, 0.7 parts per million (ppm); tungsten, 0.01 

percent). 

Gold, silver, molybdenum, copper, lead, manganese, 

tungsten, and zinc have been mined or prospected at several 

sites near the wilderness study area (fig. 4). The occurrences generally are in quartz and quartz-calcite veins associated with a rectilinear network of rhyolite dikes. The 

dikes typically strike northwest and northeast and were 

locally intruded along pre-existing faults (Haxel and others, 

1980a). The complex dike network is generally bounded 

by northwest-striking faults (fig. 2). The dike network 

includes most of the nearby mineralized occurrences and 

extends through the wilderness study area. Keith (1974) 

noted a general zoning pattern of metals in the Baboquivari 

mining district. Tungsten deposits are found in the north 

and south parts of the district and deposits of precious and 

base metals and molybdenum are present in the central part. 

Because of the zoning pattern and abundance of northwesttrending faults and dikes in the central part, Keith (1974) 

suggested the possibility of a porphyry-type deposit along 

the northwest-striking structural trend, which crosses the 

wilderness study area. 

Beryllium occurrences have been prospected in the 

Contreras Canyon area 1-2 mi east of the northern. tip. of 

the wilderness study area. The beryllium concentrations 

are in beryl-bearing, typically northwest-striking quartz 

veins and pegmatites in granite. Beryllium-enriched veins 

and dikes may therefore be present within the northweststriking structures that pass through the Baboquivari Peak 

Wilderness Study Area. 

No oil or gas discoveries are reported, and no Federal 

leases or lease applications have been filed in the Baboquivari Peak Wilderness Study Area. Ryder (1983) 

evaluated the petroleum potential of wilderness lands in 

Arizona on the basis of geologic framework and petroleum 

geology derived from published literature. The evaluation 

rated this wilderness study area among a group that has 

"zero" potential because any oil or gas accumulations 

would have been subject to migration or destruction due to 

later tectonic and magmatic activity. 

No geothermal waters or leasing activity are known 

within the Baboquivari Peak Wilderness Study Area. A 

statewide inventory and evaluation of geothermal resources 

within Arizona (Witcher and others, 1982) showed no 

geothermal resources near the Baboquivari Peak Wilderness Study Area. 

No uranium or thorium occurrences are known within 

the Baboquivari Peak Wilderness Study Area. A regional 

uranium resource evaluation by Luning and Brouilland 

(1981) rated the sedimentary and volcanic rocks in the area 

as being unfavorable for uranium occurrences because no 

reductant is present. The evaluation also rated the intrusive 

rocks as unfavorable because they are not anomalously 

uraniferous, although they showed some favorable characteristics. 

If industrial minerals are present, they are of such 

limited quantities that they do not constitute a resource. 

Coyote Mountains Wilderness Study Area 

Mining History 

Most of the mi!ling activity within the wilderness study 

area has taken place in the Bonanza mine (Cavillo Camp) 

area (No. 1, fig. 5), at the head of the no~ fork of Mendoza Canyon. Twenty unpatented mining claims cover the 

workings of the Bonanza mine area. 'Published information 

indicates that the Bonanza mine produced about 700 short 

tons of ore averaging 10 percent copper, 0.03- troy oz gold/ 

st, and 1.7 troy oz silver/st between 1909 and 1951 (Keith, 

1974). Although no other production has been recorded, 

copper minerals are exposed along rock contacts and shear 

Baboquivari Peak and Coyote Mountains Wilderness Study Areas, Pima County, Arizona E9 
31 °47'30" 

111 °37'30" 

. .(.., ~ . , ) I 0 - • ••• ~-· < 

•. ~ r . } 

··•_t' )._ !\ t 

., 

-· 

" It 

... / 

.,. .,. 

111 °35'00" 

I r - ~ ~ 

,/: 

· :/, 

111 °32'30" 

--------.. ........ _. ' 

.,..--..,... 

., ' ' ' · f' - . ~ - ' 

"--. t f ~ ...... ..... f !'" 

""'- ... ' \ 

', 9 _, ---o- : ~ . , - · :... ·, \.. ,. l, 

-.! --:--., ...... -/ 

I' 

' \ 

" 1 

I 

I 

... 

1"J\o .. • 

.... 

., 

1 MILE 

Figure 4. Location of mining and exploration activities, drainage basins, sampling sites, and elements present in 

anomalous concentrations in and near the Baboquivari Peak Wilderness Study Area, Pima County, Arizona. 

El 0 Mineral Resources of Wilderness Study Areas: Southwestern and South-Central Arizona 
zones in several nearby adits. In 1967, nine holes were 

diamond drilled for Consolidated Red Poplar Minerals Ltd. 

of Canada in the Bonanza mine area. Other previous 

mining activity includes several small prospect pits and an 

adit on the Tohono O'Odham Indian Reservation about 1 

mi north of the Bonanza mine area (No.4, fig. 5). Mining 

activity that has taken place within 3:5 mi of the wilderness study area is summarized in table 2 and on figure 5. 

Mineral Appraisal 

Copper and minor amounts of precious metals were 

mined in the Bonanza mine area. Surface cuts and underground workings were dug on contact metamorphic zones 

at the margins of dolomitic limestone and calcareous sandstone rocks that are probably roof pendants in early Tertiary Pan Tak Granite. Drilling records provide additional 

geologic information and subsurface assay data for correlation with the surface and underground workings. The 

copper occurrences are in the Devonian Martin Formation, 

a metamorphosed dolomitic limestone (Carrigan, 1971). 

Skarn zones, where the Martin Formation has been . 

metasomatically altered to assemblages of epidote, garnet, 

and diopside, contain scheelite, copper minerals, and minor 

amounts of gold and silver. Copper minerals include 

hypogene chalcopyrite, bornite, covellite, and chalcocite in 

underground workings and supergene azurite, malachite, 

and chrysocolla near the ground surface (Carrigan, 1971). 

Mining or exploration took place at nine adits and declines 

and five prospect pits in the wilderness study area (fig. 2 

of Lundby, 1987). Seventeen chip and dump samples for 

analysis were collected from the workings (figs. 5-7, table 

2 of Lundby, 1987). One of the adits and four of the 

prospect pits were examined but not sampled because of 

lack of obvious mineral occurrences and alteration. Two 

samples each assayed 0.05 troy oz gold/st; the remainder of 

the samples assayed from nil to 0.01 troy oz gold/st. Silver 

assayed as much as 3.9 troy oz/st, with most of the assays 

below 0.7 troy oz/st. Copper assayed from 0.0166 percent 

to 7.2 percent, averaging about 2 percent in most of the 

samples. Tungsten content, which does not correlate with 

copper content, ranged from nil to 0.504 percent tungsten 

trioxide (W03), with 12 of the 17 samples assaying greater 

than 0.100 percent The highest concentration of molybdenum was 0.0688 percent, with most of the assays averaging 

about 0.005 percent. Drill holes near the underground 

workings, however, contained considerabiy higher metal 

concentrations, with intercepts containing as much as 11.8 

percent copper and 5.99 troy oz silver/st. Lundby (1987) 

estimated that there are inferred subeconomic resources of 

66,500 short tons at a grade in excess of 5 percent copper, 

1.5 troy oz silver/st; and 0.15 percent tungsten trioxide. 

No oil or gas leases are recorded within 1 mi of the 

wilderness study area boundary and, according to Ryder 

(1983), the wilderness study area has no potential for oil 

and gas, because of the abundance of plutonic and gneissic 

rocks. 

No geothermal waters or leasing activity are known 

within the Coyote Mountains Wilderness Study Area. The 

wilderness study area is unfavorable for the discovery and 

development of geothermal resources (Witcher and others, 

1982). 

Most of the study area is devoid of sand or gravel 

cover. Gravel for roadbuilding and similar uses is readily 

available outside of the wilderness study area. The sedimentary rocks in the wilderness study area are generally 

impure, metamorphosed limestones of limited quantity; 

thus no limestone resource is present 

EXPLANATION 

~4 Mine-See table 1 for description /'--..... Drainage basin x6 '--"' Prospect-See table 1 for description • Sampling site 

;'~-). Mineralized area or reported mineral occurrence .... JI#, Anomalous elements 

Mines, prospects, and mineral occurrences Ag Silver 

Au Gold 

1 Black Dragon mine Ba Barium 

2 Lost Horse(?) mine Bi Bismuth 

3 Contreras Canyon area Cu Copper 

4 Allison mine Mo Molybdenum 

5 Upper Brown Canyon area Pb Lead 

6 Diablo prospect Th Thorium 

7 Jupiter mine area w Tungsten· 

8 Gold Bulfion mine 

9 Edna J placer area 

Figure 4. Continued. 

Baboquivari Peak and Coyote Mountains Wilderness Stu~y Areas, Pima County, Arizona. . Ell 
Table 1. Mines, prospects, claims, and mineral occurrences in and near the Baboquivari Peak Wilderness Study Area, Pima County, 

Arizona 

Map No. Name Commodities Geology Workings and References 

(fig. 4) production 

Black Dragon mine Manganese Discontinuous lenses, coatings, Opencuts and pits; produced Cruver and others, 1982, p. 56. 

and fracture-fillings of about 165 long tons of ore Farnham and others, 1961, p. 

manganese oxides in sheared averaging 27.6 percent 117. 

and brecciated rhyolitic manganese and 19 tons of Keith, 1974, p. 108. 

rocks. concentrate averaging 36.0 McDonnell, 1986, p. 6. 

percent manganese. 

2 Lost Horse mine(?) Molybdenum, Fracture filling in fault zone About 200 ft of underground Johnson, 1972, p. 40. 

gold, silver, that cuts metasedimentary workings; no known produc- McDonnell, 1986, p. 6. 

copper(?) rocks. tion. Mining Journal, 1938. 

3 Contreras Canyon Beryllium Beryl-bearing quartz veins and Shallow trenches and exploratory Balla, 1982, p. 21-31. 

area (includes Hop pegrnatites as thick as 3-ft in drilling; no known production. Oark, 1956, p. 10-21. 

Sage, Shamrock, granitic rocks. McDonnell, 1986, p. 6. 

Windy, and Donna Meeves and others, 1966, p. 

m claims) 21. 

4 Allison mine Silver, gold, Mineralized quartz veins in Several thousand feet of Cruver and others, 1982, p. 56. 

copper, lead, shear zones in rnetasedimen- underground workings; mill Fair, 1965, p. 83. 

manganese tary rocks and rhyolitic to ruins; produced an estimated Keith, 1974, p. 107. 

andesitic flows and intru- 47,000 short tons of ore McDonnell, 1986, p. 6. 

sions. averaging 0.22 troy oz gold/ Wilson and others, 1934, p. 

ton, 2. 7 troy oz silver/ton, and 179-180. 

minor lead and copper. Worcester, 1931. 

5 Upper Brown Gold(?), Sedimentary and silicic to Minor prospecting by past land- Cruver and others, 1982, p. 64. 

Canyon area silver(?) intermediate volcanic rocks owner along dike system; may McDonnell, 1986, p. 6, 7. 

cut by network of rhyolite be same as locality 98 listed 

dikes. by Cruver and others (1982, p. 

64); field check by U.S. 

Bureau of Mines personnel in 

1985 found no evidence of 

prospecting or production. 

6 Diablo prospect Copper, moly- Fracture zone in syenite; Thirty-ft-deep shaft; no known Donald, 1959, p. 34-40. 

bdenurn, spatial association with production. McDonnell, 1986, p. 6. 

gold, silver andesite and rhyolite dikes. 

7 Jupiter mine area Gold, silver, Discontinuous mineralized Several thousand feet of Cruver and others, 1982, p. 45. 

(includes Iowana lead, copper, quartz-calcite in fissure veins underground workings; mill Keith, 1974, p. 109. 

mine) zinc, tungsten cutting metasedimentary and ruins; exploratory drilling for McDonnell, 1986, p. 6. 

granitic rocks and dioritic large-tonnage, low-grade open Seaman, 1983, p. 51-52. 

dikes. pit operation in 197 4 yielded Wilson· and others, 1934, p. 

negative results; produced 181. 

several hundred short tons of 

ore averaging 1 troy oz gold/ 

ton, 16 troy oz silver/ton, and 

minor lead and copper. 

8 Gold Bullion mine Gold, silver, Discontinuous mineralized Several hundred feet of Cruver and others, 1982, p. 57. 

molybdenum, quartz fissure veins and underground workings; mill Donald, 1959, p. 42-44. 

copper, lead, pegrnatites as thick as 12 ft ruins; produced at least 3,100 Joseph, 1915-1916, p. 7. 

tungsten, cutting metasedimentary and tons of ore averaging about 1.0 Keith, 1974, p. 109. 

vanadium, granitic rocks and rhyolite troy oz gold/ton and 12 troy oz Kirkerno and others, 1965, p. 

zinc dikes. silver/ton; also produced ElO-Ell. 

several hundred short tons of McDonnell, 1986, p. 6. 

high-grade rnolybedenum ore Seaman, 1983, p. 49-50. 

and minor amounts of copper, Wilson and others, 1934, p. 

lead, tungsten, and vanadium. 181. 

Gold 

9 Edna J placer area Finely divided gold in a 6- to Small interrnittept placer Cruver and others, 1982, p. 

11-ft-thick gravel bar. operation; produced a few 45-46. 

tens of ounces of gold. Johnson, 1972, p. 39-40. 

Keith, 1974, p. 108. 

McDonnell, 1986, p. 6. 

Wilson, 1961, p. 81. 

E12 Mineral Resources of Wilderness Study Areas: Southwestern and South-Central Arizona 
ASSESSMENT OF MINERAL RESOURCE 

POTENTIAL 

By Gary A. Nowlan, Gordon B. Haxel, William F. Hanna, 

james A. Pitkin, and Denny V. Diveley-White 

U.S. Geological Survey 

Geology 

Geologic Framework of the Baboquivari Mountains 

Although the Baboquivari Peak and Coyote Mountains 

Wilderness Study Areas have no major rock units in common, the geologic framework of both areas has been shaped 

by the same sequence of geologic episodes that characterizes the Baboquivari Mountains as a whole. 

The oldest rocks exposed within the Baboquivari 

Mountains are Paleozoic metasedimentary rocks, restricted 

to a few small exposures in the Coyote Mountains. The 

oldest widespread lithostratigraphic unit in the Baboquivari 

Mountains comprises a thick sequence of Early Jurassic 

volcanic, subvolcanic or hypabyssal, and sedimentary 

rocks; this sequence is best preserved in the central Baboquivari Mountains. This supracrustal sequence is intruded by a Middle to Late Jurassic calc-alkaline granitoid 

suite and by a Late Jurassic weakly alkaline granite. The 

Baboquivari Mountains are a fenster (window) in the regional Late Cretaceous to early Tertiary Baboquivari thrust 

(Haxel and others, 1984). The thrust faulting caused regional metamorphism of supracrustal rocks during and after 

tectonic burial. These regionally metamorphosed rocks are 

exposed in the northern and southern Baboquivari Mountains. The later stages of Late Cretaceous to early Tertiary 

regional metamorphism were accompanied by intrusion of 

early Tertiary plutons of late- to post-kinematic peraluminous leucogranite, including the Pan Tak Granite in the 

Coyote Mountains. Middle Tertiary crustal extension 

formed low-angle normal faults and subjacent mylonitic 

shear zones at the ends of the Baboquivari Mountains-in 

the northern Coyote Mountains and in the Sierra de Pozo 

Verde (Davis, 1980; Gardulski, 1980; Wright and Haxel, 

1982; Davis and others, 1987). 

Geology of the Baboquivari Peak 

Wilderness Study Area 

The Baboquivari Peak Wilderness Study Area is underlain by four major rock units: the Early Jurassic Pitoikam and Mulberry Wash Volcanic Formations, the Late 

Jurassic perthite granite of Baboquivari Peak, and the 

middle Tertiary rhyolite of Allison Camp (fig. 2; Haxel and 

others, 1980a). Lamprophyric dikes (not shown on fig. 2) 

constitute a fifth, minor unit. 

The Pitoikam Formation (Jp, fig. 2) comprises three 

members (ascending): an unnamed lower member, the 

Contreras Conglomerate Member, and the Chiltepines 

Member. The lower member consists of nonresistant interbedded conglomerate, sandstone, and siltstone; it is 

bounded down-section by faults and intrusions; its substrate 

is not exposed. The lower member underlies only the 

northern tip of the wilderness study area. The Contreras 

Conglomerate Member comprises brown and red, resistant 

to nonresistant, thick-bedded to massive, pebble to boulder 

conglomerate and breccia, with interbeds of sandstone and 

siltstone similar to that of the Chiltepines Member. The 

Contreras Conglomerate Member underlies the northern 

one-fourth of the wilderness study area. The Chiltepines 

Member consists of brown, red, and gray, nonresistant 

siltstone, wacke, and subordinate shale; it contains interbeds of pebble conglomerate, most common in the lower 

part of the member, and uncommon interbeds of tan arenite. The upper part of the Chiltepines Member includes 

sparse intercalated volcanic rocks similar to those in the 

overlying Mulberry Wash Volcanic Formation. Clasts in 

conglomerates of the Pitoikam Formation are largely 

subangular to subrounded fragments of porphyritic to 

aphanitic, silicic to intermediate volcanic and hypabyssal 

rocks; rounded quartzite clasts are less common. 

The Mulberry Wash Volcanic Formation (Jm, fig. 2) is 

comprised of volcanic flows and flow breccias, conglomerate, sedimentary breccia, volcanic sandstone, and subvolcanic intrusions. Red, gray, brown, purple, and pink colors, 

mostly dark, are typical. Most of the volcanic rocks are 

highly altered as a result of volcanism and some are incipiently metamorphosed. Relict phenocrysts and abundances 

and ratios of relatively immobile trace elements (G.B. 

Haxel, unpub data, 1983) indicate that most of the volcanic 

rocks are rhyolitic to dacitic, and that some are comendites 

(alkali rhyolites). The comenditic volcanic rocks have anorthoclase phenocrysts. In the southern part of the outcrop 

area, the Mulberry Wash Volcanic Formation includes rare 

flows of alkaline(?) basalt. Five lithologic and stratigraphic 

subunits of the Mulberry Wash Volcanic Formation were 

mapped by Haxel and others (1980a, 1982), but only two of 

these subunits crop out within the wilderness study area. 

Both of these subunits comprise dark-brown, purple, red, 

and gray dacitic and subordinate comenditic flows and flow 

breccias; and pebble to boulder volcanic conglomerate and 

subordinate sandstone and sedimentary breccia. These two 

subunits differ only in their proportions of volcanic and 

sedimentary rocks, grade vertically into one another, and 

are shown together in figure 2. 

The Pitoikam and Mulberry Wash Volcanic Formations constitute the middle and upper parts of a volcanic 

and sedimentary sequence with a stratigraphic thickness of 

about 5 mi. The lower part of the sequence does not crop 

out within the wilderness study area. Uranium/lead zircon 

analyses determined for rhyolitic volcanic and hypabyssal 

rocks indicate that this sequence is Early Jurassic in age, 

and probably spans no more than 10 million years (Wright 

and others, 1981; Tosdal and others, 1989). 

Baboquivari Peak and Coyote Mountains Wilderness Study Areas, Pima County, Arizona E13 
m 

... 

.... 

::: 

~· 

i. 

~ 

~ c 

;; 

11 

0 

-

~ c:: 

II 

I 

(1'1 

[ 

"< 

?: 

II 

~ 

~ 

s. 

r 

.. 

~ = 

fll 

= Cl.. 

g' 

c 

:r 

Q 

~ !.. 

> .. 

§" 

= fll 

32° 

2' 

30" 

~; 

111 °35' 

~::~· 

111 °32'30" 

'~,.. f • '\ . 

~· J 

--:~.,.!If tO ... }~ ~ g 

}-

-~ 

11 P30' 111 °27'30" 

- ... •. ,._ 

'X'~ 

. EXPLANATION 

32° 

00' 

31° 

57' 

30" 

... -, I I ., _I 7 I 

"'s" ·' ' ..... .I"" 

v 

n 

" • ..,1\ 

"';...... '" 

~ t;"'. 

\.,',' "' ;'' 

'::! 

~~-~ 

, . 

I 

;:: ·~ 

-· .- I 

iO 

Pan Tak •• ; To 

·-· 

t ~· -~ ,. '-, .l2 

', 

\l ~-- ~ .,._ ~ ~ .. ~ < '2._ - r, • ~ 1 / ,, r 

~-~-\.... '!--t'-:..-~·~.~~'.-:.....-.1 '~ / ~~ J- _' -~-.' I;_) r) 

, _J .. : J 1..,..'-..y ........ J'' -',. ~ ~- ~- ~ ' : ) " looi~-'11(~·· 

,··~ ( :<··~·~,~~r ,t,~";/r>-:"'',,,' ;) ~·l' ~ ~ ~ ..... "'-· ~·"" ..... to\''~t"·l..\.!~ \, -=¥' .1' )/ .. r' 'C 

__ .. ~)<·'; ·:r,>\:;~-;,·;-~:, .· ;.,_~~. : :· -~/-·, -~ ~ .. <!;' 

· !/'.<«tf~lo:""'· ,,· APPROXIMATE BOUNDARY OF < J ~~· ·;~;\<~·;'"'· I I /' (~-, COYOTE MOUNTAINS J ./ ,'' -.' 

• _,_'· _.1<1 r ~; ');_f"'Wil.:DERNESS S,TlJOY AREA "'\'.-. · ,· .} .,_1., ' 

KI!T'.PEAK, · / , r·, (AZ-020-202) ~ -~~··1 ;r_- ' 1) )-\ _J.l, , 

-,! . - . v ' £: ) .i' ;,,. ) "' ! ( • . / . .. ' < ~ k, 

t .. ~~ ', ·'·'~\;.:~""-,~' ,. ~...,, ,- "f•('-1/ _; ,'!'; t'-' \ 

~ . -~, ~~'(~\/~-. ,) ,<\':-'/ )',_ I •+ \ , o; J,": J " '· '-'~'"'·"· (•"•t!}~--~~ t .~ .f l .. \,., . ~ ) ><-

~ .;.,. ... •'f- 0 ''t-\.~l\_l ·1-. 'i 2MILES ~ .>\If I! ' 

-:t\~-~ •- :~, ~'7 -y ~~~~~~J; (, 1 J.:·~ i I, :- " u\ . : , , . - - v ~'-./--.:.. \\ ~ r . "' ?r· • -' )I L.. ........ ~ 

-~_..,_~;)~;0:--:) ~ ~ \i ". _ - _;... ~-~-i _\· _ c"'. 1': · .. --

'' ll', 

/r 

"'J' ... .y 

... ;J...-\, :.-/ 

·..: .-/·~~./-·l""-.... f 

,, /. 

)v . 

;;--

~-. I I,' / -

... \ ., 

'\ 

••• ~!::. .::.'l ? I 

Nawt Vaya ~8 • .. W1 : ~ ' ~ xs -~':.._ ,(~) 

.(·_,;•?-,., r·-·-·-·-·-·-· 

I •' ~ 

~ 

·~ •:;:.·· I 

1 

2 Jn '3 

4 

5 

6 

7 

8 

.,.--- -· I c==) 'via - :-·fj li:.«r.-' --rr- . ·- 't,i·. ' ,, 

""'•co,.. C:: \ • /\ I I ' I ~ I 

\i } ~). 

l.\ 

~,;-oW""~ 

Au l 

""' ! ··:? Cu ) 

Fe •. , \ J,, ... 

} '-

,. ~ ',t~ ~ La "i. Ji'?_, { 7 Nb I" ·~--~~ I -11; l, Pb <C . ·- i ; Th '• ., '- "\_ ~- ' y i <! J 

Figure 5. Location of mining and exploration activities, drainage basins, sampling sites, and elements present in anomalous concentrations in and near 

the Coyote Mountains Wilderness Study Area, Pima County, Arizona. 

Mine-See table 2 

for description 

Prospect or claimSee table 2 for 

description 

Mineralized area or 

claim group 

Mines, prospects, 

claims, and mineralized areas 

Bonanza mine area 

South prospect 

North prospect 

Reservation prospects 

E1 Conquistadors 

claims 

Black Hawk group 

of claims 

Jean E group of 

claims 

Roadside mine 

Drainage basin 

Sampling site 

Anomalous 

elements 

Gold 

Copper 

Iron 

Lanthanum 

Niobium 

Lead 

Thorium 

Yttrium 
Table 2. 

Map No. 

(fig. 5) 

2 

3 

4 

5 

6 

7 

8 

Mines, prospects, and claims in and near the Coyote Mountains Wilderness Study Area 

Name Commodities 

Bonanza mine Copper, silver, 

area tungsten, molybdenum, zinc, gold 

South prospect Copper, silver 

North prospect Copper 

Reservation Copper 

prospects 

El Conquista- Uranium 

dors claims 

Black Hawk Manganese 

group of 

claims 

Jean E group Manganese, copper, 

of claims zinc 

Roadside mine Copper, silver, gold, 

mercury 

Geology 

Contact-metamorphic deposits 

at margins of, and partiallyreplacing, dolomitic limestone 

and calcareous sandstone 

blocks that are probably roof 

pendants in granite 

Skarn zone between calcareous 

rocks and granite. 

Bedding-plane fault in altered 

metasedimentary rocks. 

Contact-metamorphic deposits 

granite-limestone contact. 

Pegmatite in granite. 

Discontinuous narrow stringers 

and shattered zones 

containing manganese oxides; 

rhyolitic volcanic rocks. 

Fractures and shattered areas 

containing manganese oxides; 

rhyolitic volcanic rocks. 

Disseminations, streaks, and 

fracture fillings in shear zone 

cutting andesitic volcanic 

rocks and sandstone; aplitic 

or pegmatitic quartz 

monzonite at depth. 

Workings and 

production 

Over 400 ft of underground 

workings; nine diamond drill 

holes; produced about 700 short 

tons of ore averaging 10 

percent copper, 0.03 troy oz 

gold/st. and 1.7 troy oz silver/ 

st. 

A 35-ft-deep inclined shaft, a 

prospect pit, and two diamond 

drill holes; no known production. 

A 27-ft-long adit; no known 

production. 

Several small prospect pits and 

an adit; no known production. 

Swface workings; no production. 

At least 15 cuts and pits; 

produced about 46 long tons of 

sorted ore averaging 20 percent 

manganese. 

Several shafts and 12 or more 

pits and cuts; produced about 

100 long tons of ore averaging 

about 8 percent manganese. 

Shaft and diamond drilling; no 

reported production. 

References 

Carrigan, 1971, p. 47-60. 

Cruver and others, 1982, 

p. 43-44. 

Keith, 1974, p. 116. 

Lundby, 1987, p. 6-17. 

Lundby, 1987, p. 17-19. 

Lundby, 1987, p. 17-19. 

Lundby, 1987, p. 19. 

Cruver and others, 1982, 

p. 59. 

U.S. Atomic Energy Commission, 1970, p. 48. 

Cruver and others, 1982, 

p. 51-52. 

Farnham and others, 1961, 

p. 116-117. 

Keith, 1974, p. 116. 

Cruver and others, 1982, 

P· 51. 

Farnham and others, 1961, 

p. 115-116. 

Keith, 1974, p. 116. 

Cruver and others, 1982, 

p. 58. 

Keith, 1974, p. 117. 

The Mulberry Wash Volcanic Formation is intruded by 

the perthite granite of Baboquivari Peak (Jb, fig. 2), which 

forms a small pluton exposed from the southwestern part of 

the wilderness study area west to the west edge of the 

Baboquivari Mountains. The unit consists of reddishbrown, coarse-grained, leucocratic, perthite granite and 

subordinate quartz perthite syenite (petrographic nomenclature of Streckeisen, 1976). Accessory minerals are biotite 

and amphibole (hornblende in some places and hastingsite 

in others), which commonly are strongly altered. Ironoxide staining is pervasive. Interpretation of slightly discordant uranium/lead analyses of zircon suggests an age of 

approximately 147 Ma for these rocks (J.E. Wright, written 

common., 1982). 

(Tac, fig. 2). Within and adjacent to the wilderness study 

area, this rhyolite forms a rectilinear network of northwestand northeast-trending dikes. These dikes range from a few 

to 70 ft thick and as much as 4 mi long. A particularly 

prominent dike dominates the northwest-trending ridge 

between upper Brown and Thomas Canyons. This unit 

comprises yellowish-weathering, sparsely to strongly porphyritic rhyolite containing phenocrysts of quartz, alkali 

feldspar, and, in most rocks, plagioclase and (or) altered 

biotite; subordinate trachydacite dikes, without quartz phenocrysts, are less abundant but widespread (volcanic rock 

nomenclature of LeBas and others, 1986). Some dikes 

have flow banding along their margins. In a few places, for 

example, the west side of the central part of the wilderness 

study area, rhyolite dikes evidently were intruded along 

pre-existing faults. The dikes commonly contain hematite 

pseudomorphs after pyrite in the Jupiter Canyon area, south 

The Pitoikam and Mulberry Wash Volcanic Formations and the perthite granite of Baboquivari Peak are intruded by dikes and stocks of the rhyolite of Allison Camp 

Baboquivari Peak and Coyote Mountains Wilderness Study Areas, Pima County, Arizona El 5 
of the area shown on figure 2 (Seaman, 1983). Interpretation of potassium/argon ages and discordant uranium/lead 

zircon ages indicates that the ages of the rhyolite of Allison 

Camp and related volcanic rocks are 24±2 Ma (R.M. 

Tosdal, written common., 1982; J .E. Wright, written common., 1981). 

Dikes and small irregular intrusions of nonresistant, 

typically dark-gray, mesocratic to locally melanocratic 

lamprophyre or, less commonly, microdiorite are widely 

scattered throughout most of the Baboquivari Mountains 

(unit not shown on fig. 2). Dikes are typically 3 to 16 ft 

thick. The few lamprophyric intrusions within the wilderness study area apparently have no preferred orientation 

and are too small and poorly exposed to map. In several 

outcrops, the lamprophyric intrusions are consistently and 

sharply intruded by dikes of the rhyolite of Allison Camp. 

One of the clearest and most accessible of these outcrops is 

located in upper Sabino Canyon, along the trail about 70ft 

east of the wilderness study area. Although no isotopic 

ages have been determined directly for the lamprophyric 

intrusions in the Baboquivari Mountains, regional geologic 

relations (Riggs, 1985, 1987; G.B. Haxel, unpub. data, 

1987) suggest that they are middle Tertiary in age and 

probably approximately the same age as the rhyolite of 

Allison Camp. 

The geologic map (fig. 2) includes geologic map units 

that are outside the Baboquivari Peak Wilderness Study 

Area. The additional units are the Early Jurassic Ali 

Molina Formation, the Early Jurassic Chiuli Shaik Formation, the Early Jurassic rhyodacite porphyry of Tinaja 

Spring, the Middle Jurassic granodiorite of Kitt Peak, the 

Late Jurassic granite of Pavo Kug Wash, Tertiary conglomerate, Tertiary andesitic and dacitic flows and intrusions, 

Tertiary intrusions of hornblende granodiorite, and upper 

Tertiary and Quaternary gravel and alluvium. Descriptions 

of these units are modified from Haxel and others (1980a, 

1982). 

In the area of figure 2, the Early Jurassic Ali Molina 

Formation (Ja, fig. 2) consists of schistose metaconglomerate, quartzite, and metamorphosed rhyodacite flows, flow 

breccia, and welded tuff. 

The Early Jurassic Chiuli Shaik Formation (Jcs, fig. 2) 

rests unconformably on the Early Jurassic Mulberry Wash 

Volcanic Formation. The unit is composed of rhyodacite 

tuff, andesite flows, volcanic breccia, conglomerate, sandstone, and rart: limestone lenses. 

The Early Jurassic rhyodaci~ porphyry of Tinaja 

Spring (Jt, fig. 2) is an intrusive porphyry with a finegrained, crystalline groundmass containing phenocrysts of 

plagioclase, potassium feldspar, quartz, altered biotite, and 

magnetite. The unit is commonly silicified and iron oxide 

stained in the area represented by figure 2. 

In the area of figure 2, the Middle Jurassic granodiorite 

of Kitt Pe8k (Jk, fig. 2) comprises medium- to coarse-

. grained hornblende-biotite and biotite granodiorite and 

subordinate monzogranite. It is uniformly porphyritic, with 

potassium feldspar phenocrysts 1-2 in. long. Sphene is 

locally present 

The Late Jurassic granite of Pavo Kug Wash (Jpk, fig. 

2) is fine- to coarse-grained, equigranular, leucocratic, 

biotite monzogranite and syenogranite, typically containing 

conspicuous greasy-gray quartz. Quartz veins are locally 

common. The unit intrudes the granodiorite of Kitt Peak 

along mapped contacts and as north-northwest-trending 

dikes. 

Unit Tc (fig. 2) consists mainly of pebble to boulder 

conglomerate unconformably overlying the Chiuli Shaik 

Formation. Clasts of the Late Jurassic perthite granite of 

Baboquivari Peak are locally abundant Northwest of the 

corner of the area represented by figure 2, the unit includes 

conglomerate with subordinate sedimentary breccia and 

friable, thoroughly weathered basal conglomerate interpreted by Fair (1965, p. 29) to represent in situ weathering 

of underlying source rocks. 

Unit Ta (fig. 2) includes andesitic and dacitic volcanic 

flows, flow breccia, tuff, dikes and other small intrusions, 

and intrusive breccia. Locally it rests nonconformably on 

the perthite granite of Baboquivari Peak. 

Tertiary hornblende granodiorite (Tgd, fig. 2) consists 

of scattered small intrusions and unmapped dikes of fine- to 

medium-grained, equigranular to porphyritic hornblende 

and biotite-hornblende granodiorite and monzogranite. 

This rock type typically contains hornblende laths 0.1--0.2 

in. long. In the area represented by figure 2, the intrusions 

are most co_mmon near Contreras and Sabino Canyons. 

Unit QTg (fig. 2) includes unconsolidated and weakly 

consolidated gravel, sand, and minor silt along washes, on 

pediments, in alluvial fans, and forming low hills adjacent 

to the mountains. 

The structure of the Baboquivari Peak Wilderness 

Study Area is relatively simple. Overall, the Pitoikam 

Formation and the overlying Mulberry Wash Volcanic 

Formation dip homoclinally westward. Dips range generally from 20° to 60° northwest to southwest. Channels and 

crossbeds in conglomerates and sandstones uniformly indicate units are younger to the west Along the intrusive 

contact of the perthite granite of Baboquivari Peak with the 

Mulberry Wash Volcanic Formation, the granite is locally 

fmer grained than elsewhere and the volcanic rocks are 

locally hornfelsic. Small dikes of granite in the volcanic 

rocks are rare. Three mapped high-angle faults, marked by 

gouge zones as much as 8 ft wide, are present in the wilderness study area. A small fault passes through the saddle 

northeast of Baboquivari Peak. A more important fault in 

Sycamore Canyon extends into, and dies out within, the 

central part of the study area. The northernmost tip of the 

study area lies within the Foothill Truck Trail fault zone. 

This major fault extends northwest-southeastward for about 

12 mi within and along the west edge of the Baboquivari 

Mountains and separates the metamorphosed Early Jurassic 

supracrustal rocks of the higher Baboquivari Mountains 

from the largely unmetamorphosed Pitoikam Formation of 

E16 Mineral Resources of Wilderness Study Areas: Southwestern and South-Central Arizona 
the Fresnal Canyon area. The Foothill Truck Trail fault 

probably has had Tertiary movement although it probably 

originated in Early Jurassic time (G.B. Haxel and J.E. 

Wright, written common., 1984). 

Geology of the Coyote Mountains Wilderness Study Area 

The Coyote Mountains (fig. 3) are a crudely triangular 

range bounded on the west by a middle or late Tertiary 

high-angle fault with the east side upthrown,: on the north 

by a composite north-dipping fault (the Ajo Road fault) 

consisting of a middle Tertiary detachment fault modified 

by a younger high-angle normal fault, and on the southeast 

by Tertiary and Quaternary alluvium in Altar Valley. 

The Coyote Mountains Wilderness Study Area is 

underlain by five major rock units: Paleozoic metasedimentary rocks, Middle Jurassic diorite of Nawt Vaya, 

Middle Jurassic granodiorite of Kitt Peak, Late Jurassic 

granite of Pavo Kug Wash, and the early Tertiary Pan Tak 

Granite (fig. 3; Haxel and others, 1980a; Wright and Haxel, 

1982). Lamprophyre dikes, similar to those in the Baboquivari Peak Wilderness Study Area, constitute a sixth, 

minor unit (not shown on fig. 3). The Pan Tak Granite 

forms a small pluton, partially exposed in the northern and 

central Coyote Mountains, that intrudes the Paleozoic and 

Jurassic rocks. The Paleozoic rocks underlie a relatively 

small area and form thin "rafts" shallowly underlain by the 

Pan Tak Granite. These rafts are discontinuous remnants of 

a single body in the north-central part of the Pan Tak 

pluton. 

The Paleozoic metasedimentary rocks comprise two 

map units: calc-silicate schist and quartzite (Pzc and Pzq, 

respectively, fig. 3). The calc-silicate schist unit contains 

calc-silicate schist and granofels, quartzofeldspathic schist, 

quartzite, and schistose marble; accessory minerals in the 

unit include diopside, garnet, wollastonite, hornblende, 

clinohumite, and phlogopite. Most of the quartzite unit is 

micaceous. The calc-silicate schist is locally altered to 

diopside or garnet skarn that contains minor idocrase. The 

quartzite is derived from the Cambrian Bolsa Quartzite and 

the calc-silicate unit from the Cambrian Abrigo Formation 

and Devonian Martin Formation (Carrigan, 1971). 

The diorite of Nawt Vaya (Jn, fig. 3) comprises mesocratic, compositionally and texturally heterogeneous biotite-hornblende quartz diorite and tonalite, and subordinate hornblende-phenocrystic hornblende diorite and augite 

hornblendite. In contrast to the heterogeneity of these 

dioritic rocks, the granodiorite of Kitt Peak (Jk, fig. 3) is 

rather homogeneo~s throughout the Baboquivari Mountains. The granodiorite of Kitt Peak consists of medium- to 

coarse-grained, sphene-bearing hornblende-biotite granodiorite and subordinate monzogranite and quartz monzodiorite. Lenticular, fme-grained, biotite-rich monzodioritic 

enclaves are common. The unit commonly contains potassium feldspar phenocrysts. The granodiorite of Kitt Peak is 

intruded by the granite of P~vo Kug Wash (Jpk, fig. 3), 

coarse- to fine-grained, equigranular, texturally heterogeneous, leucocratic biotite monzogranite and syenogranite, 

typically containing greasy-gray quartz. In most of their 

extensive outcrop areas in the Quinlan Mountains and 

northern and central Baboquivari Mountains, these granitoids are unfoliated. In the Coyote Mountains and western 

Quinlan Mountains, where these granitoids were metamorphosed (see below), they commonly are foliated. In some 

places, the diorite of Nawt Vaya was converted to biotiterich schist. The granodiorite of Kitt Peak and granite of 

Pavo Kug Wash yielded Middle to Late Jurassic concordant 

uranium/lead zircon ages (J.E. Wright, written common., 

1981). Field relations and petrologic data suggest that the 

diorite of Nawt Vaya forms the mafic end-member of a 

compositional series with the granodiorite and granite 

units; a Middle Jurassic age for this unit is therefore inferred. The petrology and regional relations of these Jurassic granitoids are discussed by Tosdal and others (1989). 

The Pan Tak Granite (Tp, fig. 3) is a high-silica (73-77 

weight percent silica), moderately alumina-rich (1 to 3 percent normative corundum) leucogranite characterized by 

various combinations of the accessory minerals biotite, 

muscovite, and garnet. In general, the granite consists of 

two intrusive phases that are intermixed on the scale of feet 

to hundreds of feet an older phase of reddish-weathering, 

leucocratic, medium-grained granite and a younger phase 

of whitish-weathering, highly leucocratic (alaskitic), medium-grained to pegmatitic granite. Pegmatite in some ' 

places grades into and in other places intrudes the younger 

granite phase. Overall, the two phases appear nearly equal 

in abundance. Gamet typically is more common in the 

younger phase. Textural relations (in thin section) indicate 

that muscovite is a primary, magmatic mineral. 

The geologic map (fig. 3) includes geologic map units 

in addition to the ones that underlie the wilderness study 

area. The additional units are Jurassic volcanic rocks, the 

Cretaceous(?) Sand Wells Formation, the Cretaceous 

Roskruge Volcanics, late Tertiary conglomerate, and late 

Tertiary and Quaternary gravel and alluvium. 

Unit Jv (fig. 3) comprises volcanic rocks similar to 

rocks in the Baboquivari Mountains and has been assigned 

a Jurassic age (Wright and Haxel, 1982; Tosdal and others, 

1989). The Cretaceous(?) Sand Wells Formation (Ks, fig. 

3) is composed of sandstone, siltstone, conglomerate, 

mudstone, and volcanic breccias and flows of intermediate 

composition (Haxel and others, 1980b; Wright and Haxel, 

1982). The Roskruge Volcanics (Kr, fig. 3) are made up of 

a series of brightly colored ash flows and volcanic breccias 

that are primarily quartz latite to rhyodacite in composition 

(Bikerman, 1967, 1968). Unit Tc (fig. 3) comprises consolidated or semiconsolidated conglomerates (Wright and 

Haxel, 1982) that in some cases have probably been offset 

by Tertiary faults. Unit QTg (fig. 3) includes unconsolidated and weakly consolidated gravel, sand, and minor silt· 

along washes, on pediments, and in alluvial fans. 

Baboquivari Peak and Coyote Mountains Wilderness Study Areas, Pima County, Arizona E17 
Contacts between the Pan Tak Granite and country 

rocks consistently are sharply intrusive. The granite is not 

migmatitic, neither in the sense of outcrop-scale injection 

or granitization of its country rocks, nor in the sense of 

origin by in situ anatexis of the country rock. The granite 

is conspicuously free of enclaves. In most areas of the 

Coyote Mountains, the country rocks of the Pan Tak Granite are intruded by swarms of pegmatite dikes. These dikes 

typically are 1 to 15 ft thick and dip gently east-southeastward. Pegmatite dikes are most abundant in the re-entrant 

on the southwest side of the pluton, and decrease in abundance southward away from the pluton and northward and 

northeastward into the center of the pluton. Rugged topography in the northwestern and central parts of the Pan Tak 

pluton is controlled by a prominent set of widely spaced, 

moderately east-northeast-dipping joints. The uranium/lead 

zircon crystallization age of the Pan Tak Granite is 58±2 

Ma (Wright and Haxel, 1982). 

Two metamorphic fabrics were imposed on the Pan 

Tak Granite and its country rocks. The older of these 

fabrics, defined by moderately west-southwest-dipping 

foliation and subordinate southwest-plunging lineation, is a 

regional metamorphic fabric broadly contemporaneous 

with the intrusion of the Pan Tak -Granite (Wright and 

Haxel, 1982; Haxel and others~ 1984). This fabric is 

widespread in the Jurassic granitoid rocks, ubiquitous in the 

Paleozoic calc-silicate schist, and fairly common in the 

older phase of the Pan Tak Granite. The younger phase of 

the granite generally crosscuts this fabric. On the northern 

slope of the Coyote Mountains, both phases of the Pan Tak 

Granite and many of the rafts or inclusions of quartzite or 

diorite in the granite are variably overprinted by a moderately north-northeast-dipping mylonitic foliation accompanied by a strong north-plunging lineation. This post-Pan 

Tak Granite fabric is penetrative in the northwestern Coyote Mountains. Elsewhere on the northern slope of the 

Coyote Mountains, the mylonitic fabric is variably and 

sporadically developed in tabular or lensoidal domains that 

decrease in size and abundance southward. The mylonitic 

fabric is essentially absent south of the ridge that trends 

east from Coyote Peak. Thus, the Tertiary mylonitic fabric 

is present only in the northwestern part of the Coyote 

Mountains Wilderness Study Area (fig. 3). 

Geochemistry 

Reconnaissance geochemical surveys of the Baboquivari Peak and Coyote Mountains Wilderness Study 

Areas were conducted in 1986. Samples of drainage sediment were collected at 10 sites near the Baboquivari Peak 

Wilderness Study Area (fig. 4) and at 15 sites near the 

Coyote Mountains Wilderness Study Area (fig. 5). In 

addition, nine samples of mineralized rock were sampled 

from dumps and adits at two sites in the Coyote Mountains 

Wilderness Study Area. Because many of the samples 

from near the Baboquivari Peak Wilderness Study Area 

contained anomalous concentrations of gold and silver, 

samples of drainage sediment were collected at 14 additional stream sites in 1987. 

Stream-sediment samples and panned-concentrate 

samples derived from stream sediments were chosen as the 

routine sample media for this reconnaissance study because 

they represent a composite of material eroded from the 

drainage basin of the stream sampled. Both wilderness 

study areas occupy areas of high relief where streams locally are only incipiently developed. This is especially true 

of the Baboquivari Peak Wilderness Study Area, where all 

sampling sites are 300 ft to 1.3 mi outside its boundaries. 

Stream-sampling sites are located both inside the Coyote 

Mountains Wilderness Study Area and as much as 1.1 mi 

outside its boundaries. 

Three samples were collected at each stream site. One 

of the samples was air dried and then sieved through a 30-

mesh stainless-steel sieve. A 30-mesh sieve was used 

rather than the more conventional 80-mesh to lessen the 

possible dilution effects windblown material might have in 

this desert environment. The two additional samples each 

consisted of 20 lb of stream sediment that were panned 

until about 1.5 oz or less remained. One of these pannedconcentrate samples was further concentrated by a series of 

steps involving heavy liquids and magnetic separations to 

produce a "nonmagnetic heavy-mineral concentrate., The 

other panned concentrate received no further treatment 

before chemical analysis for gold and was termed a "raw 

panned concentrate., 

The minus-30-mesh stream-sediment samples and 

nonmagnetic heavy-mineral-concentrate samples were analyzed by emission spectrography for iron, magnesium, 

calcium, titanium, manganese, silver, arsenic, gold, boron, 

barium, beryllium, bismuth, cadmium, cobalt, chromium, 

copper, lanthanum, molybdenum, niobium, nickel, lead, 

antimony, scandium, tin, strontium, vanadium, tungsten, 

yttrium, zinc, zirconium, and thorium. In addition, the 

minus-30-mesh stream-sediment samples were analyzed for 

gold by atomic absorption, for arsenic, bismuth, cadmium, 

antimony, and zinc by inductively coupled plasma spectroscopy, for mercury by atomic absorption, and for uranium 

and thorium by delayed neutron-activation analysis. The 

raw panned-concentrate samples were analyzed for gold by 

atomic absorption. Tabulations of the analytical results, 

descriptions of methods of sample preparation, and descriptions and references for the analytical methods are given by 

Adrian and others (1987, 1988). 

Geochemistry of the Baboquivari Peak 

Wilderness Study Area 

Minus-30-mesh stream-sediment results were compared with results for 971 samples of minus-30-mesh 

stream sediment from the nearby Ajo 1° by 2° quadrangle 

E18 Mineral Resources of Wilderness Study Areas: Southwestern and South-Central Arizona 
(Theobald and Barton, 1983). These comparisons revealed 

no anomalous minus-30-mesh stream-sediment samples 

near the Baboquivari Peak Wilderness Study Area except 

that silver and copper are each weakly anomalous in 

samples from three sites. 

Results from nonmagnetic heavy-mineral concentrate 

samples were compared with results from 952 samples 

collected in the Ajo 1° by 2° quadrangle (Theobald and 

Barton, 1983). In contrast to the minus-30-mesh streamsediment results, results from nonmagnetic heavy-mineral 

concentrate samples revealed striking gold-silver anomalies 

and also showed that anomalous concentrations of barium, 

bismuth, lead, molybdenum, thorium, and tungsten are 

present. Gold analyses of raw panned-concentrate samples 

confirmed the presence of a strong gold anomaly. 

No detectable gold was measured in 952 samples of 

nonmagnetic heavy-mineral concentrate from the Ajo 1° by 

2° quadrangle (Theobald and Barton, 1983, table 2). The 

lower limit of determination is 20 ppm. Twelve of the 24 

samples from the study area contain detectable gold, ranging from 20 ppm (0.58 troy oz/st) to more than 1,000 ppm 

(29 troy oz/st). The median value for the 12 samples 

containing detectable gold is 250 ppm (7 .3 troy oz/st). 

Gold analyses of raw panned-concentrate samples have 

several advantages over gold analyses of nonmagnetic 

heavy-mineral-concentrate samples. They have the advantages of larger sample size and thus greater homogeneity; 

minimal sample preparation and thus fewer handling steps; 

and sensitivity that is less than crustal abundance (approximately 0.002 ppm) if the gold concentration of the raw 

panned-concentrate sample is converted to the concentration of the original stream sediment. The analytical method 

will detect as little as 0.05 ppm gold in a 10-gram sample. 

We consider concentrations of 0.3 ppm (0.009 troy oz/st) or 

greater to be anomalous; this is a conservative level and 

might be as low as 0.1 ppm (0.003 troy oz/st). Twenty of 

the 24 raw panned-concentrate samples contain anomalous 

concentrations of gold. The highest concentration of gold 

in any raw panned-concentrate sample from the study area 

is 52 ppm (1.5 troy oz/st), which converts to approximately 

0.16 ppm gold (0.005 troy oz/st) in the original unpanned 

stream sediment. 

The analyses of nonmagnetic heavy-mineral-concentrate samples show that gold and silver are present in equal 

amounts and that concentrations of the two metals vary 

sympathetically. Examination of the samples under microscope revealed no silver or probable silver-bearing minerals other than gold. Samples from all four of the major 

canyon systems draining the wilderness study area (Contreras, Sabino, Brown, and Thomas) contain anomalous 

amounts of gold and silver (fig. 4). 

In addition to anomalous gold and silver, samples of 

nonmagnetic heavy-mineral concentrate from the study 

area have anomalous concentrations of barium, bismuth, 

lead, molybdenum, thorium, and tungsten (fig. 4). Barium 

is anomalous in about one-half of the samples. Bismuth is 

anomalous in one-sixth of the samples. Lead is anomalous 

in one-fourth of the samples. Molybdenum is anomalous in 

one-third of the samples and tungsten in one-half. One-half 

of the samples contain anomalous concentrations of thorium. 

Geochemical patterns indicate that gold and silver 

concentrations are largely independent of the concentrations of the other anomalous elements. However, microscopic examination shows a correspondence between visible gold and pyrite. Thorium concentrations are independent of the other elements except that they tend to be negatively correlated with barium concentrations. Barium, 

bismuth, lead, molybdenum, and tungsten appear to be 

complexly interrelated. 

Geochemistry of the Coyote Mountains 

Wilderness Study Area 

Results were compared with results from the Ajo 1° by 

2° quadrangle (Theobald and Barton, 1983), as described 

under Baboquivari Peak Wilderness Study Area results. 

Three raw panned-concentrate samples from the northeastem part of the Coyote Mountains Wilderness Study Area 

contain anomalous concentrations of gold (fig. 5); evidence 

of prospecting in this part of the study area is almost nonexistent. The nonmagnetic heavy-mineral concentrate 

samples from the easternmost of these three sample sites 

contains an anomalous concentration of lead. The minus30-mesh stream-sediment sample collected about 0.8 mi 

downstream from the Bonanza mine area (fig. 5) contains 

anomalous concentrations of copper_ and lanthanum. Thorium concentrations are anomalous in several samples of 

stream sediment and nonmagnetic heavy-mineral concentrate. The average niobium concentration in nonmagnetic 

heavy-mineral-concentrate samples is about 55 ppm, which 

is higher than the less than 50 ppm average in the Ajo 1 o 

by 2° quadrangle. The yttrium concentration is anomalous 

in one stream-sediment sample. 

Geophysics 

Aeromagnetics 

The Baboquivari Peak and Coyote Mountains Wilderness Study Areas are covered by a single aeromagnetic 

survey (U.S. Geological Survey, 1980) having sufficient 

resolution to define anomalies about 1 mil or larger. Totalintensity magnetic anomalies are defined by east-west traverses spaced about 1 mi apart at a nominal altitude of 4,000 

ft above sea level but draped over higher topography. 

The Baboquivari Peak Wilderness Study Area is 

transected by two prominent magnetic anomalies: a largeamplitude low in the center of the wilderness study area 

and a ,small-amplitude high in the southern part of the 

Baboquivari Peak and Coyote Mountains Wilderness Study Areas, Pima County, Arizona E19 
wilderness study area. The high is probably caused by 

dacitic to andesitic flows and flow breccias of the Mulberry 

Wash Volcanic Formation. The low is enigmatic: it is 

spatially associated with the perthite granite of Baboquivari 

Peak, but this granite is undoubtedly too deficient in 

magnetic minerals to be the source of a large-amplitude 

anomaly. One possible although unlikely explanation is 

that the low is the dipole effect of the volcanic rocks 

causing the high to the south. If so, the volcanic rocks must 

carry a strong total magnetization (average dipole moment 

per unit volume) having a post-tectonic direction upwardly 

and northwardly inclined-neither normal nor reversed but 

between these two polarities. Another, more likely, possibility is that the exposed granite is underlain by reversely 

magnetized, intermediate to mafic igneous rocks. The low 

is similar in character to a low associated with Tertiary 

basalt 6 mi west of the wilderness study area. Thus, the 

low in the Baboquivari Peak Wilderness Study Area may 

be caused by buried mafic subvolcanic rocks that perhaps 

fed andesitic or basaltic flows now eroded or displaced. 

The Coyote Mountains Wilderness Study Area is characterized by low magnetic gradients forming flanks of two 

highs separated by a low. A broad high covering the 

northeastern part of the wilderness study area is associated 

with a variety of mapped rock units but is probably caused 

largely by the diorite of Nawt Vaya, which is inferred to be 

more extensive in the subsurface than at the sirrface. A 

small-amplitude high at the southern margin of the wilderness study area appears to be caused by a lobe of the 

granodiorite of Kitt Peak, which extends eastward from the 

main mass of the pluton. The main mass of the pluton is 

associated with a large-amplitude high. The intervening 

low, forming the southeastern nose of a feature centered 

over Jurassic volcanic rocks 4 mi northwest of the wilderness study area, has an unknown source. This low, covering the northwestern part of the wilderness study area, may 

be caused by reversely magnetized subvolcanic rocks extending in the subsurface southeastward from the terrane of 

volcanic rocks. A second possibility is that the low may be 

caused by either a decrease in magnetic mineral content or 

an increase in domain size of magnetic minerals in exposed 

felsic intrusive rocks. A third possibility is the existence of 

altered intermediate to mafic rocks in the subsurface. 

Aerial Gamma-.ray Spectrometry 

Aerial gamma-ray spectrometry measures the nearsurface (0 to 18 in.) distribution of the natural radioelements potassium (K), uranium (eU), and thorium (eTh). 

The "e" (for equivalent) prefix denotes the potential for 

disequilibrium in the uranium and thorium decay series. 

Because the distribution of these elements is controlled by 

geologic processes, aerial gamma-ray measurements can be 

used in geologic mapping, mineral exploration, and the 

understanding of geologic processes. 

The spectrometry data used for this report were obtained between 1974 and 1981 for the National Uranium 

Resource Evaluation (NURE) program of the U.S. Department of Energy. Flightline spacing was usually at 3- and 

6-mi intervals, which yields data suitable for producing 

contour and other maps only at scales of 1:500,000 and 

smaller. All NURE flight altitudes were 400 ft above 

ground level, allowing the effective detection of terrestrial 

gamma radiation from a swath 800-ft wide along the flightline. 

NURE data that include the Baboquivari and Coyote 

Mountains Wilderness Study Areas are presented on contour maps and color composite image maps (Duval, 1983) 

at scales of 1:500,000 and 1:1,000,000. Spectrometric data 

described below were derived from the NURE reports for 

the Nogales and Tucson 1 o by 2° quadrangles (U.S. Department of Energy, 1978a,b). 

The Baboquivari Peak Wilderness Study Area is characterized by radioelement concentrations of 2.0 to 2.5 

percent K, 4 to 6 ppm eU, and 10 to 15 ppm eTh. These 

concentrations are determined from two NURE flightlines 

that cross the wilderness study area and provide sparse 

control for defining radioelement distribution for the area. 

These concentrations are reasonable (not anomalous) for 

the Mesozoic and Cenozoic crystalline rocks that are present in the wilderness study area. The sparse flightline 

coverage of the study area precludes deriving any direct 

information on mineral resource potential from the aerial 

gamma-ray data. 

The Coyote Mountains Wilderness Study Area is characterized by radioelement concentrations of 2.3 to 2.7 

percent K, 5 to 7 ppm eU, and 10 to 12 ppm eTh. These 

concentrations are determined from two NURE flightlines 

that cross the study area and provide sparse control for 

defining radioelement distribution. Within the study area, 

K concentrations are locally 2.7 to 3.0 percent east of 

Coyote Peak. These concentrations possibly reflect the 

presence of the Pan Tak Granite (Wright and Haxel, 1982) 

within the study area; whether they have any significance 

to copper, silver, and tungsten mineralization in the Coyote 

Mountains Wilderness Study Area (Lundby, 1987) is not 

known. A limited area of 8 to 9 ppm eU lies east and 

outside of the wilderness study area, north of 32° latitude. 

This occurrence is in the area of the Ajo Road detachment 

fault (Wright and Haxel, 1982, fig. 2) and could be the 

"anomaly" mentioned in a report on uranium favorability of 

metamorphic core complexes; this report concludes that 

" ... the Coyote Mountains probably have very low favorability for uranium occurrence ... " (Kluth, 1980, p. 595). For 

the Coyote Mountains Wilderness Study Area, the radioelement concentrations are reasonable (not anomalous) for the 

Mesozoic and Cenozoic crystalline rocks that are present in 

the wilderness study area. The sparse flightline coverage of 

the wilderness study area precludes deriving any direct 

information on mineral resource potential from the aerial 

gamma-ray data. 

E20 Mineral Resources of Wilderness Study Areas: Southwestern and South-Central Arizona 
Mineral Resource Potential of the 

Baboquivari Peak Wilderness Study Area 

No known mineral deposits or occurrences are within 

the Baboquivari Peak Wilderness Study Area. However, 

the study area lies within the Baboquivari mining district, 

which has produced gold, silver, copper, lead, zinc, manganese, tungsten, and molybdenum from polymetallic veins 

that are spatially associated with high-angle faults and 

Tertiary felsic-to-intermediate dikes. Most of the vein 

deposits are small, but a major past producer is 3 mi west 

of the wilderness study area. Small amounts of placer gold 

have been recovered within 3 mi. Small amounts of beryl 

and bismuth are present in scattered simple pegmatite/ 

quartz veins that are within 2 mi of the wilderness study 

area. High concentrations of gold and silver in streamsediment and panned-concentrate samples and visible gold 

in panned-concentrate samples from streams in the study 

area are nearly ubiquitous. The source of these high 

amounts of gold and silver may be polymetallic veins 

similar to those nearby or the precious metals may be from 

types of deposits not known in the area but for which there 

is permissive evidence as discussed below. 

Polymetallic Vein Deposits 

The entire Baboquivari Peak Wilderness Study Area 

has high potential, certainty level C, for resources of gold, 

silver, copper, lead, zinc, barium, bismuth, manganese, 

molybdenum, or tungsten in polymetallic veins. Favorable 

criteria for polymetallic vein deposits listed by Cox (1986) 

are present in and within about 3 mi of the wilderness study 

area. Nearby mineral deposits interpreted to be polymetallic vein deposits include the Allison mine, the Black 

Dragon mine, the Diablo prospect, the Gold Bullion mine, 

the Jupiter and Iowana mines, and the Lost Horse mine(?) 

(table 1 and fig. 4). 

In a study of geology and ore potential near the Jupiter 

mine (fig. 4), Seaman (1983) suggested that the base- and 

precious-metal mineralization probably preceded the intrusion of the rhyolite dikes. Evidence for the suggestion is 

the pervasive phyllic and propylitic alteration in the area 

around the Jupiter mine that presumably accompanied 

mineralization but is found only in pre-Tertiary rocks. 

However, the spatial association of mineralized rocks and 

dikes suggests that Tertiary mineralization cannot be ruled 

out If the nearby mineral deposits formed in the Mesozoic, 

favorable criteria for polymetallic veins include known 

vein deposits, extensive faulting, brecciation, presence of at 

least one small granitic intrusion (Seaman, 1983, p. 28), 

and strong geochemical anomalies for gold, silver, barium, 

bismuth, lead, molybdenum, and tungsten in panned-concentrate samples derived from stream sediment If the 

nearby mineral deposits formed in the Cenozoic, favorable 

criteria, in addition to the above, include an association 

with Tertiary rhyolite dikes and the intrusion of those dikes 

into sedimentary and metamorphic terrain. Although mineralized rocks have not been definitively recognized within 

the wilderness study area, bedrock geology and favorable 

structures spatially associated with nearby mineral deposits 

extend into the wilderness study area. 

Beryllium- Bismuth- and Thorium-Bearing Pegmatites 

The northern part of the Baboquivari Peak Wilderness 

Study Area has low potential, certainty level B, for beryllium and bismuth resources in pegmatites or quartz veins 

and the entire wilderness study area has low potential, 

certainty level B, for thorium deposits in pegmatites. Beryl 

and the bismuth minerals, bismuthinite, bismutite, and 

native bismuth are found in pegmatites 1-2 mi northeast of 

the wilderness study area (Clark, 1956, p. 19); anomalous 

bismuth concentrations in some panned-concentrate 

samples from the middle to northern part of the study area 

suggest that similar pegmatites may be present there. 

Anomalous thorium concentrations in panned-concentrate 

samples from throughout the study area may be evidence of 

pegmatites throu~hout the entire wilderness study area. 

Paleoplacer Gold-Silver Deposits 

The entire Baboquivari Peak Wilderness Study Area 

has low potential, certainty level B, for resources of gold 

and silver in placers in the Early Jurassic Pitoikam Formation and Mulberry Wash Volcanic Formation. The lack of 

correlation between gold-silver concentrations and concentrations of barium, bismuth, molybdenum, lead, and tungsten in samples from streams in the study area suggests that 

the source of the gold and silver may be different than that 

of the other five metals. Consistent gold-silver ratios argue 

that a single mineralizing event accounts for the precious 

metals. The existence of paleoplacer gold-silver deposits is 

presented here as one of two permissive, but speculative, 

mineral-deposit models that might explain the anomalous 

gold and silver. 

Samples containing anomalous concentrations of gold 

and silver are not limited to any general part of the sampled 

area. Therefore, if mineralization is limited to a particular 

rock unit, that unit must be widespread. In addition to the 

network of dikes formed by the middle Tertiary rhyolite of 

Allison Camp, the unit common to most of the sampled 

area is the Early Jurassic Pitoikam Formation, which is 

comprised of conglomerate, sandstone, siltstone, and minor 

mudstone or shale (Haxel and others, 1980a). The uppermost part of the formation includes volcanic conglomerate 

and dacitic flows. Overlying the Pitoikam Formation 

within the sampled area is the Early Jurassic Mulberry 

Wash Volcanic Formation (Haxel and others, 1980a). 

Subunits of the Mulberry Wash Volcanic Formation within 

the wilderness study area are composed of volcanic debris 

and dacitic (or andesitic) flows, flow breccia, and dikes. 

Baboquivari Peak and Coyote Mountains Wilderness Study Areas, Pima County, Arizona E21 
Nearby subunits of the Mulberry Wash Volcanic Formation, not exposed in the· sampled area, are composed of 

rhyodacite, latite, and andesite flows and rhyodacite volcanic conglomerate. The geologic setting is one of volcanic activity that could have been accompanied by precious-metal mineralization with subsequent formation of 

precious-metal placer deposits that are now being eroded 

and carried into present-day streams. The separation of 

gold-silver from the other anomalous elements in the 

sampled area could result from this recycling of gold and 

silver. 

Gold-Silver Deposits Associated with an 

Inferred Porphyry Molybdenum Deposit 

The entire Baboquivari Peak Wilderness Study Area 

has low potential, certainty level B, for gold and silver 

resources as veins or disseminated deposits in the outer 

halo of an inferred molybdenum deposit. The southern part 

of the wilderness study area has low potential, certainty 

level B, for molybdenum resources in that inferred porphyry molybdenum deposit. This mineral-deposit model is 

the other permissive, but speculative, model presented here 

as a possible explanation for anomalous gold and silver in 

samples from streams of the study area. This model is 

closely related to the model for polymetallic vein deposits 

discussed earlier but differs in that the veins or disseminated deposits are inferred to be part of a porphyry system, 

especially the outer part of a porphyry system. Therefore, 

the following will discuss evidence for the presence of a 

porphyry molybdenum deposit near the wilderness study 

area even though primary emphasis is on the potential for 

gold-silver deposits. 

Gold is not characteristically associated with Climaxtype porphyry molybdenum deposits (Ludington, 1986) and 

the Climax-type model will not be considered here even 

though favorable criteria are present near the wilderness 

study area. The presence of a porphyry copper deposit 

cannot be completely excluded, either, because many of the 

characteristics of a porphyry copper system are the same as 

for a low-fluorine porphyry molybdenum system. However, the Baboquivari Mountains lie within what has been 

termed southern Papago terrane (Haxel and others, 1984), 

which is outside of the southern Arizona porphyry-copper 

province (Schmitt, 1966; Titley, 1982) and lacks many of 

the geologic characteristics of the porphyry-copper province. 

The presence of a porphyry molybdenum deposit near 

Jupiter Canyon, about 2 mi south of the Baboquivari Peak 

Wilderness Study Area, was suggested by Seaman (1983) .. 

This suggestion was b3sed on the existence of pervasive 

phyllic and propylitic alteration in bedrock, the presence of 

felsic inuusive rocks, and anomalous molybdenum, tungsten, and fluorine concentrations in samples from adits, 

dumps, and pits (Seaman, 1983, p. 5). Samples of water 

from springs and shallow wells 3 to 5 mi southwest of 

Jupiter Canyon contain highly anomalous concentrations of 

molybdenum (Ficklin and others, 1978, 1980). A hole 

drilled to about 500ft in Jupiter Canyon in the Early Jurassic rhyodacite porphyry of Tinaja Spring (fig. 2) penetrated 

only propylitic and phyllic alteration (Seaman, 1983, p. 

39-43, 84); thus if a porphyry molybdenum deposit exists, 

it is probably 1,500-3,000 ft below the surface (Seaman, 

1983, p. 84-86) and (or) laterally displaced from Jupiter 

Canyon. 

Favorable criteria for low-fluorine porphyry molybdenum deposits (Theodore, 1986) in the study area include 

pervasive propylitic and phyllic alteration in the Jupiter 

mine area (No.7, fig. 4), presence of felsic inuusive rocks, 

Mesozoic or Tertiary age of mineralization, numerous 

faults, strong geochemical anomalies for gold, silver, barium, bismuth, lead, molybdenum, or tungsten in pannedconcentrate samples, tungsten in the form of scheelite in 

panned-concentrate samples from streams draining the 

wilderness study area, and presence of polymetallic vein 

deposits of gold, silver, copper, lead, zinc, and manganese 

in the Jupiter Canyon area. 

Although speculative, this model of gold-silver deposits associated with an inferred porphyry-molybdenum system warrants consideration. 

Other Commodities 

The Baboquivari Peak Wilderness Study Area has low 

potential, certainty level C, for resources of oil, gas, geothermal energy, and industrial minerals for the reasons 

presented in the section "Mineral appraisal of the Baboquivari Peak Wilderness Study Area." 

Mineral Resource Potential of the 

Coyote Mountains Wilderness Study Area 

The Coyote Mountains Wilderness Study Area lies 

within the Coyote mining district. Most of the production 

of the district came from the Bonanza mine (No. 1, fig. 5), 

which is located within the wilderness study area. Production from the Bonanza mine area was from small copper 

skarn and polymetallic replacement deposits. A uraniumbearing pegmatite is near the wilderness study area and 

simple pegmatites are common throughout the wilderness 

study area. In the northeastern part of the wilderness study 

area there is permissive evidence (discussed below) for 

gold deposits associated with a detachment fault. 

Copper Skarn and Polymetallic Replacement Deposits 

An area of the Coyote Mountains Wilderness Study 

Area underlain by Paleozoic metasedimentary rocks has 

high potential, certainty level C, for resources of copper, 

tungsten, gold, silver, molybdenum, and zinc in skarn and 

E22 Mineral Resources of Wilderness Study Areas: Southwestern and South-Central Arizona 
polymetallic replacement deposits. Favorable criteria for 

copper skarn (Cox and Theodore, 1986) and polymetallic 

replacement deposits (Morris, 1986) within the wilderness 

study area include an intrusive contact between granitic 

rocks and calcareous or carbonate-bearing rocks, altered 

and mineralized rocks at the contact, an association between copper-bearing skarn and polymetallic replacement 

deposits, and anomalous concentrations of gold in pannedconcentrate samples from streams draining areas peripheral 

to the central, copper-dominated mineralized area. 

In addition to copper, tungsten, gold, and silver, minor 

amounts of zinc and molybdenum were produced from the 

Bonanza mine area. Mineralized and altered samples from 

adits, dumps, and prospects in the Bonanza mine area 

contain concentrations of 1 ,000 ppm or greater of barium, 

silver, and zinc (Adrian and others, 1987; Lundby, 1987). 

Some samples contain greater than 20,000 ppm copper or 

greater than 10,000 ppm tungsten and as much as 150 ppm 

tin. Mineralization resulted from the intrusion of the early 

Tertiary Pan Tak Granite into Paleozoic metasedimentary 

rocks. Mineralized zones are present along the contact 

between the intrusion and metasedimentary rocks or as 

replacements in limestone (Carrigan, 1971). Most of the 

production came from replacement zones associated with 

skarn; in some cases, specific limestone beds were replaced 

without the development of skarn. Despite high concentrations of copper and tungsten in mineralized rock samples, 

the copper concentration is anomalous in only one drainage 

sample from the study area-a stream sediment downstream from the Bonanza mine area; no drainage samples 

contain anomalous concentrations of tungsten (fig. 5). 

Skarn minerals in the Bonanza mine area include epidote, garnet, diopside, and magnetite (Carrigan, 1971, p. 

47-60). Altered and mineralized zones are. confined to the 

metasedimentary rocks except for minor zones of argillic 

and sericitic alteration and oxide copper in the granite 

where the granite is in contact with skarn. Because copper 

is the predominant metal in the skarn, it is classified as a 

copper skarn (Einaudi and others, 1981, p. 320, 330). 

Mineralized Pegmatites 

The entire Coyote Mountains Wilderness Study Area 

has low potential, certainty level B, for resources of thorium, niobium, uranium, lanthanum, and yttrium in pegmatites. Favorable criteria include abundance of pegmatites, 

anomalous concentrations of thorium, niobium, yttrium, 

and lanthanum in drainage samples, and occurrence of a 

mineralized pegmatite less than 1(l mi· southeast of the 

wilderness study area. . 

Elements often associated with late granitic differentiates tend to be present in anomalous or above-average 

concentrations in stream-sediment or panned-concentrate 

samples from streams in the study area (fig. 5). No complex pegmatites have been recognized within the wilderness study area. However, anomalous concentrations of 

thorium, niobium, yttrium, and lanthanum in samples of 

drainage sediment and the occurrence of uranium in a 

pegmatite southeast of the wilderness study area (No.5, fig. 

5, and table 2) suggest that complex pegmatites could be 

present 

Gold Deposits Associated with Detachment Faults 

The northeastern part of the Coyote Mountains Wilderness Study Area has moderate potential, certainty level B, 

for gold resources in deposits associated with the Ajo Road 

detachment fault. Panned-concentrate samples from the 

northeastern part of the wilderness study area contain 

anomalous concentrations of gold. The gold anomaly is 

mild compared to the Baboquivari Peak area, but proximity 

to the Ajo Road detachment fault gives added significance 

to the anomaly and suggests that the detachment-fault 

model (Spencer and Welty, 1986) may be applicable. The 

following discussion attempts to show that the geologic 

setting is favorable for the formation of detachment-faultrelated mineral deposits and that known deposits near the 

detachment fault may indeed be related to the fault. 

Favorable criteria for the detachment-fault model include anomalous concentrations of gold in panned-concentrate samples, existence of manganese deposits in the upper 

plate of the Ajo Road detachment fault 3 mi northwest of 

the wilderness study area, and occurrence of base and 

precious metals in the upper plate 2.5 mi north of the 

wilderness study area. 

Some base- and precious-metal mineral deposits are 

associated with detachment faults in western Arizona and 

southeastern California (Spencer and Welty, 1986). These 

deposits are characterized by early copper and iron sulfides, 

later specular hematite and manganese oxides, and still 

later chrysocolla and malachite. According to the model, 

redox gradients with depth along the detachment fault can 

result in the separation of oxides of manganese from oxides 

of iron. Also, the interface between reduced and oxidized 

fluids moves as movement takes plaGe along the fault and 

can result in the deposition of both reduced and oxidized 

forms of copper, iron, and probably other metals in the 

same deposit Mineralization associated with the Ajo Road 

detachment fault may be represented by known copper, 

sliver, gold, mercury, and manganese mineralization in 

fault zones in the upper plate. At the Roadside mine (No. 

8, fig. 5) native copper, copper carbonates and oxides, 

sparse copper sulfides, tetrahedrite, mercurian tettahedrite, -

cinnabar, and native mercury are present in a fault zone in 

volcanic and sedimentary rocks as disseminations, streaks, 

and fracture fillings (Keith, 1974, p. 117). Information on 

the Roadside mine is sparse, but perhaps what has been 

interpreted as deep (800 ft) oxidation in the mine actually 

represents primary deposition of oxidized forms of copper. 

If so, the Roadside mine fits the detachment-fault model 

where oxidized and reduced forms ~f copper are deposited 

Baboquivari Peak and Coyote Mountains Wilderness Study··Areas, Pima County, Arizona E23 
at the same place but at different times. At the Black Hawk 

and Jean E localities (Nos. 6 and 7, fig. 5), manganese 

oxides filL fractures in high-angle fault zones in volcanic 

rocks (Farnham ·and others, 1961, p. 115-116; Keith, 1974, 

p. 116). These deposits of manganese oxides fit the detachment-fault model of separation of manganese oxides from 

iron oxides. 

Other Commodities 

The Coyote Mountains Wilderness Study Area has low 

potential, certainty level C, for resources of oil, gas, geothermal energy, and industrial minerals for the reasons presented under "Mineral Appraisal of the Coyote Mountains 

Wilderness Study Area." 

REFERENCES CITED 

Adrian, B.M.; Fey, D.L., Bradley, L.A., O'Leary, R.M., and 

Nowlan, G.A., 1987, Analytical results and sample locality 

maps of stream-sediment, panned-concentrate, and rock_ 

samples from the Baboquivari Peak, Coyote Mountains, and 

Table Top Mountains Wilderness Study Areas, Pima, Pinal, 

and Maricopa Counties, Arizona: U.S. Geological Survey 

Open-File Report 87-163, 23 p., 1 plate. 

Adrian, B.M., Hageman, P.L., Sharkey, J.D., and Nowlan, G.A., 

1988, Analytical results and sample locality map of stream 

sediment and panned-concentrate samples from the Baboquivari Peak Wilderness Study Area, Pima County, Arizona: U.S. Geological Survey Open-File Report 88-427, 14 p. 

Balla, J.C., 1962, Geology and geochemistry of beryllium in 

southern Arizona: Tucson, University of Arizona, M.S. thesis, 76 p. 

Beikman, H.M., Hinkle, M.E., Frieders, Twila, Marcus, S.M., and 

Edward, J.R., 1983, Mineral surveys by the Geological Survey and the Bureau of Mines of Bureau of Land Management 

wilderness study areas: U.S. Geological Survey Circular 901, 

28 p. 

Bikerman, Michael, 1967, Isotopic studies in the Roskruge 

Mountains, Pima County, Arizona: Geological Society of 

-America Bulletin, v. 78, p. 1029-1036. 

Bikerman, Michael, 1968, The geology of the Roskruge Mountains-A brief summary, in Titley, S.R., ed., Southern Arizona guidebook ill: Tucson, Arizona Geological Society, p. 

18~191. 

Carrigan, F.J., 1971, A geologic investigation of contact metamorphic deposits in the Coyote MountaiJts, Pima County, Arizona: Tuc~n. University of Arizona, M.S. thesis, 67 p. 

Clark, J.L., 1956, Structure and petrology pertaining to a beryl 

deposit, Baboquivari Mountains, Arizona: · Tucson, University 

of Arizona, M.S. thesis, 49 p. 

Cohen, K.K., 1981, Utilization of the paleomagnetism of Mesozoic miogeosynclinal and magmatic arc deposition from the 

North America Western Cordilleran as a test of the sinistral 

displacement along the Mojave-Sonora megashear: Pittsburg, 

Penn., University of Pittsburgh, Ph.D. dissertation, 712 p. 

Cohen, K.K., Anderson, T .H., Schmidt, V .A., and Haxel, Gordon, 

1981, Pa).eomagnetic results from Early Jurassic units from 

the Sil Nakya Hills and the Baboquivari Mountains, southcentral Arizona [abs.]: Geological Society of America Abstracts with Programs, v. 13, p. 428. 

Cox, D.P., 1986, Descriptive model of polymetallic veins, in Cox, 

D.P., and Singer, D.A., eds., Mineral deposit models: U.S. 

Geological Survey Bulletin 1693, p. 125. 

Cox, D.P., and Theodore, T.G., 1986, Descriptive model of Cu 

skarn deposits, in Cox, D.P., and Singer, D.A., eds., Mineral 

deposit models: U.S. Geological Survey Bulletin 1693, p. 86. 

Cruver, S.K., Cruver, Jack, Wodzicki, A., and Krason, Jan, 1982, 

Geology, energy and mineral resources assessment of the Kitt 

Peak area, Arizona: Geoexplorers International, Inc., Denver, 

Colorado, prepared for U.S. Dept. of the Interior, Bureau of 

Land Management. 

Davis, G.H., 1980, Structural characteristics of metamorphic core 

complexes, southern 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. 

35-77. 

Davis, G.H., Gardulski, A.F., and Lister, G.S., 1987, Shear zone 

origin of quartzite mylonite and mylonitic pegmatite in the 

Coyote Mountains metamorphic core complex, Arizona: 

Journal of Structural Geology, v. 9, no. 3, p. 289-297. 

Defense Mapping Agency Aerospace Center, 1974, World relative gravity reference network, North America, Part 2: Defense Mapping Agency Aerospace Center Reference Publication 25, with supplement updating gravity values to the International Gravity Standardization Net 1971. 

__ 1975, Holding, storage, and retrieval of gravity data: 

Defense Mapping Agency Aerospace Center, Publication 

RP-75-003, 33 p. 

Donald, P.G., 1959, Geology of the Fresnal Peak area, Baboquivari Mountains, Arizona: Tucson, University of Arizona, M.S. thesis, 45 p. 

Duval, J.S., 1983, Composite color images of aerial gamma-ray 

spectrometric data: Geophysics, v. 48, n:o. 6, p. 722-735. 

Einaudi, M.T., Meinert, L.D., and Newberry, R.J., 1981, Skarn 

deposits, in Skinner, B.J., ed., Economic Geology Seventyfifth Anniversary Volume: Lancaster, Penn., Economic 

Geology Publishing Co., p. 317-391. 

Fair, C.L., 1965, Geology of the Fresnal Canyon area, Baboquivari Mountains, Pima County, Arizona: Tucson, University of Arizona, Ph.D. thesis, 89 p. 

Farmer, G.L., and DePaolo, D.J., 1984, Origin of Mesozoic and 

Tertiary granite in the Western United States and implications 

for pre-Mesozoic crustal structure; pt. 2. Nd and Sr isotopic 

studies of unmineralized and Cu- and Mo-mineralized granite 

in the Precambrian craton: Journal of Geophysical Research, 

v. 89, no. B12, p. 10,141-10,160. 

Farnham, L.L., Stewart, L.A., and Delong, C.W., 1961, Manganese deposits of eastern Arizona: U.S. Bureau of Mines 

Information Circular IC-7990, 178 p. 

Ficklin, W.H., Ashton, Wheeler, Preston, D.J., and Nowlan, G.A., 

1978, Analytical results for 89 water samples from the Papago 

Indian Rese~ation, Arizona: U.S. Geological Society OpenFile Report 78-1092, 29 p. 

Ficklin, W.H., Preston, D.J., Stanley, A.R., and Nowlan, G.A., 

1980, Analytical results for 127 water samples from the 

Papago Indian Reservation and vicinity, Arizona: U.S. Geological Survey Open-File Report 80-310, 22 p. 

E24 Mineral Resources of Wilderness Study Areas: Southwestern and South-Central Arizona 
Galbraith, F.W., Heindl, L.A., and Sykes, G.G., 1959, Volcanic 

craters of the Pinacate Mountains, Sonora, Mexico, Trip 6, 

Road log, Arizona Geological Society, Southern Arizona 

Guidebook IT: Geological Society of America, Cordilleran 

Section, April 2-6, 1959, Tucson, p. 253-270. 

Gardulski, A.F., 1980, A structural and petrologic analysis of a 

quartzite-pegmatite tectonite, Coyote Mountains, southern 

Arizona: Tucson, University of Arizona, M.S. thesis, 69 p., 

scale 1 :4,800. 

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

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

Report 84-787, 42 p. 

Haxel, G.B., 1987, Trace-element systematics of peraluminous 

leucogranites, Baboquivari Mountains chain, south-central 

Arizona [abs.]: Geological Society of America Abstracts with 

Programs, v. 19, p. 388. 

Haxel, Gordon, May, D.J., and Tosdal, R.M., 1982, Reconnaissance geologic map of the Presumido Peak 15' quadrangle, 

Arizona; U.S. Geological Survey Miscellaneous Field Studies 

Map MF-1378, scale 1:62,500 

Haxel, Gordon, May, D.J., Wright, I.E., and Tosdal, R.M., 1980a, 

Reconnaissance geologic map of the Baboquivari Peak quadrangle, Arizona: U.S. Geological Survey Miscellaneous Field 

Studies Map MF-1251, scale 1:62,500. 

Haxel, Gordon, Tosdal, R.M., May, D.J., and Wright, I.E., 1984, 

Latest Cretaceous and early Tertiary orogenesis in southcentral Arizona: thrust faulting, regional metamorphism, and 

granitic plutonism: Geological Society of America Bulletin, 

v. 95, p. 631-653. 

Haxel, Gordon, Wright, I.E., May, D.J., and Tosdal, R.M., 1980b, 

Reconnaissance geology of the Mesozoic and lower Cenozoic 

rocks of the southern Papago Indian Reservation, Arizona: A 

preliminary report: Arizona Geological Society Digest, v. 12, 

p. 17-29. 

Heindl, L.A., and Fair, C.L., 1965, Mesozoic(?) rocks in the 

Baboquivari Mountains, Papago Indian Reservation, Arizona: 

U.S. Geological Survey Bulletin 1194-1, 12 p. 

Johnson, M.G., 1972, Placer gold deposits of Arizona: U.S. 

Geological Survey Bulletin 1355, 103 p. 

Joseph, P.E., 1915-16, Molybdenum: University of Arizona 

Bulletin No. 5, 15 p. 

Keith, S.B., 1974, Index of mining properties in Piina County, 

Arizona: Arizona Bureau of Mines Bulletin 189, 156 p. 

Keith, W.J., 1976, Reconnaissance geologic map of the San 

Vicente and Cocoraque Butte 15' quadrangles, Arizona: U.S. 

Geological Survey Miscellaneous Field Studies Map MF-769, 

scale 1:62,500. 

Kirkemo, Harold, Anderson, C.A., and Creasey, S.C., 1965, Investigations of molybdenum deposits in the conterminous 

United States: U.S. Geological Survey Bulletin 1182-E, 90 p. 

Kluth, C.F., 1980, Geology, uranium favorability, uranium occurrences, and tectonic maps of individual Cordilleran metamorphic core complexes, Coyote Mountains, Appendix D, in 

Coney, P.J., and Reynolds, S.J., eds., Cordilleran metamorphic core complexes and their uranium favorability: U.S. 

Department of Energy Open-File Report GJBX-258 (80), p. 

594-595. 

Kurtz, W.L., 1955, Geology of a portion of the Coyote Mountains, 

Pima County, Arizona: Tucson, University of Arizona, M.S. 

thesis, 90 p. 

LeBas, M.J., LeMaitre, R.W., Streckeisen, A., and Zanettin, B., 

1986, A chemical classification of volcanic rocks based on the 

total alkali-silica diagram: Journal of Petrology, v. 27, p. 

745-750. 

Ludington, S.D., 1986, Descriptive model of Climax Mo deposits, 

in Cox, D.P., and Singer, D.A., eds., Mineral deposit models: 

U.S. Geological Survey Bulletin 1693, p. 73. 

Lundby, William, 1987, Mineral resources of the Coyote Mountains Wilderness Study Area (AZ-020-202), Pima County, 

Arizona: U.S. Bureau of Mines Mineral Land Assessment 

Open-Fil~ Report MLA 34-87, 25 p., 1 plate. 

Luning, R.H., and Brouilland, L.A., 1981, National uranium resource evaluation,- Nogales quadrangle, Arizona:· U.S. Department of Energy Open-File Report PGJ/F-130(82), 70 p. 

Lysonski, J.C., Sumner, J.S., Aiken, C.L.V., and Schmidt, J.S., 

1980, Complete residual Bouguer gravity anomaly map of 

Arizona: Bureau of Geology and Mineral Technology, 

Tucson, scale 1:500,000. 

McDonnell, J.R., Jr., 1986, Mineral investigation of the Baboquivari Peak Wilderness Study Area (AZ-020-203B), Pima 

County, Arizona: U.S. Bureau of Mines Mineral Land Assessment Open-File Report MLA 9-86, 10 p. 

McKelvey, V.E., 1972, Mineral resource estimates and public 

-policy: American Scientist, v. 60, no. 1, p. 32-40. 

Meeves, H.C., Harrer, C.M., Salsbury, M.H., Konselrnan, A.S., 

and Shannon, S.S., Jr., 1966, Reconnaissance of berylliumbearing pegmatite deposits in six western states: U.S. Bureau 

of Mines Information Circular 8298, 34 p. 

Min, M.M., 1965, Petrography and alteration of the Kitt Peak 

area, Pima County, Arizona: Tucson, University of Arizona, 

M.S. thesis, 90 p. 

Mining Journal, The, 1938, Concentrates from western statesArizona: The Mining Journal [Phoenix, Arizona], v. 22, no. 

3, p. 18. 

Morris, H.T., 1986, Descriptive model of polymetallic replacement deposits, in Cox, D.P., and Singer, D.A., eds., Mineral 

deposit models: U.S. Geological Survey Bulletin 1693, p. 99. 

Nowlan, G.A., 1988, Significance of gold and silver in drainage 

samples from the vicinity of the Baboquivari Peak Wilderness 

Study Area, Pima County, Arizona: U.S. Geological Survey 

Open-File Report 88-426, 13 p., 1 plate. 

Reynolds, S.J., 1980, Uranium "favorability of Cordilleran metamorphic core complexes, Chap. 6 in Coney, P.J., and Reynolds, S.J., eds., Cordilleran metamorphic core complexes and 

their uranium favorability: U.S. Department of Energy OpenFile Report GJBX-258(80), p. 311-321. 

Riggs, N.R., 1985, Stratigraphy, structure and mineralization of 

the Pajarito Mmmtains, Santa Cruz Cmmty, Arizona: Tucson, 

University of Arizona, M.S. thesis, 102 p. 

Riggs, N.R., 1987, Stratigraphy, structure, and geoch.emistry of 

Mesozoic rocks in the Pajarito Mountains, Santa Cruz County, 

Arizona, in Dickinson, W .R., and Klute, M.A., eds., Mesozoic 

rocks of southern Arizona and adjacent areas: Arizona Geological Society Digest, v. 18, p. 165-175. 

Ryder, R.T., 1983, Petroleum potential of wilderness lands in 

Arizona, in Miller, B.M., ed., Petroleum potential of wilderness lands in the western United States: U.S. Geological 

Survey Circular 902-A-P, p. C1-C22. 

Schmitt, H.A., 1966, The porphyry copper deposits in their regional setting, in Titley, S.R., and Hicks, C.L., eds., Geology 

Baboquivari Peak and Coyote Mountains Wilderness Study Areas, Pima County, Arizona E2S 
of the porphyry copper deposits, southwestern North America: 

Tucson. University of Arizona Press, p. 17-33. 

Schnabel, Lorraine, Welty, J.W., Trapp, R.A., and Reynolds, S.J., 

1986, Bibliography for metallic mineral districts in Pima and 

Santa Cruz Counties, Arizona: Arizona Bureau of Geology 

and Mineral Technology, Circular 26, 44 p. 

Seaman, S.J., 1983, Geology and ore potential of the Jupiter 

Canyon region, Baboquivari Mountains, Arizona: Tucson, 

University of Arizona, M.S. thesis, 99 p. 

Solomon. G.C., and Taylor, H.P., Jr., 1981, Oxygen isotope study 

of Mesozoic batholithic rocks in southeastern California and 

southern Arizona, in Howard, K.A., Carr, M.D., and Miller, 

D.M., eds., Tectonic framework of the Mojave and Sonoran 

Deserts, California and Arizona: U.S. Geological Survey 

Open-File Report 81-503, p. 100. 

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

detachment faults in the lower Colorado trough, Arizona and 

California: Geology, v. 14, p. 195-198. 

Stipp, T.F., Haigler, L.B., Alto, B.R., and Sutherland, H.L., 

compilers, 1967, Reported occurrences of selected minerals in 

Arizona: U.S. Geological Survey Mineral Investigations 

Resource Map MR-46, scale 1:500,000. 

Streckeisen, A., 1976, To each plutonic rock its proper name: 

Earth-Science Reviews, v. 12, p. 1-33. 

Theobald, P.K., and Barton, H.N., 1983, Statistical parameters for 

resource evaluation of geochemical data from the Ajo 1° x 2° 

quadrangle, Arizona: U.S. Geological Survey Open-File 

Report 83-734, 40 p. 

Theodore, T.G., 1986, Descriptive model of porphyry Mo, low-F, 

in Cox, D.P., and Singer, D.A., eds., Mineral deposit models: 

U.S. Geological Survey Bulletin 1693, p. 120. 

Titley, S .R., 1982, Geologic setting of porphyry copper deposits, 

in Titley, S.R., ed., Advances in geology of the porphyry 

copper deposits, southwestern North America: Tucson, University of Arizona Press, p. 37-58. 

Tosdal, R.M., 1981, Late Cretaceous to late Tertiary base- and 

precious-metal mineralization, south-central Arizona [abs.], in 

~oward, K.A., Carr, M.D., and Miller, D.M., eds., Tectonic 

framework of the Mojave and Sonoran Deserts, California and 

Arizona: U.S. Geological Survey Open-File Report 81-503, 

p. 113-115. 

Tosdal, R.M., and Briskey, J.A., 1981, Middle Tertiary fissurevein base- and precious-metal mineralization. Papago Indian 

Reservation, south-central Arizona [abs.]: Geological Society 

of America Abstracts with Programs, Cordilleran Section, v. 

13, no. 2, p. 110. 

Tosdal, R.M., Haxel, G.B., and Wright, I.E., 1989, Jurassic geology of the Sonoran Desert region. southern Arizona, southeastern California, and northernmost Sonora: Construction of 

a continental-margin magmatic arc, in Reynolds, S.J., and 

Jenney, J.P., eds., Summary of Arizona Geology: Arizona 

Geological Society Digest, v. 17. 

U.S. Atomic Energy Commission, 1970, Preliminary reconnaissance for uranium in Pima and Pinal Counties, Arizona, 1950 

to 1957: U.S. Atomic Energy Commission Report RME-159, 

100 p. 

U.S. Bureau of Mines and U.S. Geological Survey, 1980, Principles of a resource/reserve classification for minerals: U.S. 

Geological Survey Circular 831, 5 p. 

U.S. Department of Energy, 1978a, Aerial radiometric and magnetic reconnaissance survey of portions of Arizona-New 

Mexico, Nogales quadrangle: U.S. Department of Energy 

Open-File Report GffiX-23(79), v. 2-E. 

__ 1978b, Aerial radiometric and magnetic reconnaissance 

survey of portions of Arizona-New Mexico, Tucson quadrangle: U.S. Department of Energy Open-File Report 

GffiX-23(79), v. 2-C. 

U.S. Geological Survey, 1980, Composite aeromagnetic map of 

the Papago area, Arizona: U.S. Geological Survey Open-File 

Report 80-56, scale 1:250,000. 

Wargo, J.G., 1954, Geology of a portion of the Coyote-Quinlan 

Complex, Pima County, Arizona: Tucson, University of 

Arizona, M.S. thesis, 67 p. 

Wargo, J.G., and Kurtz, W.L., 1956, Geology and tectonic features of the Coyote Mountains, Arizona: The Ohio Journal of 

Science, v. 56, p. 10-16. 

Wilson. E.D., 1961, Arizona gold placers, in Gold placers and 

placering in Arizona: Arizona Bureau of Mines Bulletin 168, 

p. 11-86. 

Wilson. E.D., Cunningham, J.B., and Butler, G.M., 1934, Arizona 

lode gold mines and gold mining: Arizona Bureau of Mines 

Bulletin 137, 261 p. 

Witcher, J.C., Stone, Claudia, and Hahman, W.R., Sr., 1982, 

Geothermal resources of Arizona: Arizona Bureau of Geology and Mineral Technology map, scale 1:500,000. 

Worcester, A.W., 1931, Allison mine ofEl Oro Mining Company: 

The Mining Journal [Phoenix, Arizona], v. 15, no. 3, p. 5-6. 

Wright, J .E., and Haxel, Gordon. 1982, A garnet-two mica granite, Coyote Mountains, southern Arizona: geologic setting, 

uranium lead isotopic systematics of zircon. and nature of the 

granite source region: Geological Society of America Bulletin, v. 93, no. 11, p. 1176-1188. 

Wright, I.E., Haxel, Gordon, and May, D.J., 1981, Early Jurassic 

uranium-lead isotopic ages for Mesozoic supracrustal sequences, Papago Indian Reservation, southern Arizona [abs.]: 

Geological Society of America Abstracts with Programs, v. 

13, p. 115. 

E26 Mineral Resources-of Wilderness Study Areas: Southwestern and South-Central 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 characteristics indicate a geologic environment favorable for resource occurrence, where interpretations of data 

indicate a high degree of likelihood for resource accumulation, where data support mineral-deposit models 

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

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

have been active in at least part of the area. 

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

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

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

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

l LOW minerai 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. 

r 

...J 

< 

~ 

z 

w 

..... 

0 

0.. 

w 

u 

c.:: 

:::::> 

0 

V) 

w 

c.:: 

u.. 

0 

...J 

w 

> w 

...J 

A 

U/A 

UNKNOWN POTENTIAL 

Abstracted with minor modifications from: 

B c 

H/B H/C 

HIGH POTENTIAL HIGH POTENTIAL 

M/B M/C 

MODERATE POTENTIAL MODERATE POTENTIAL 

UB uc 

LOW POTENTIAL LOW POTENTIAL 

LEVEL OF CERTAINTY 

D 

H/D 

HIGH POTENTIAL 

MID 

MODERATE POTENTIAL 

UD 

LOW POTENTIAL 

N/0 

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, soulh-amtral 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. 

E28 Mineral Resources of Wilderness Study Areas: Southwestern and South-Central Arizona 
RESOURCE/RESERVE CLASSIFICATION 

IDENTIFIED RESOURCES UNDISCOVERED RESOURCES 

Demonstrated Probability Range 

Inferred 

Measured Indicated Hypothetical Speculative 

I Inferred 

I 

ECONOMIC Reserves 

Reserves 

I I 

----,--------------- Inferred 

-~-

MARGINALLY Marginal Marginal ECONOMIC Reserves Reserves ____ ..!_ ____ - I I ----------- -~-

SUB- Demonstrated Inferred 

Subeconomic Subeconomic 

ECONOMIC Resources Resources I I I 

Major elements of mineral resource classification, excluding reserve base and inferred re~rve 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. 

Baboquivari Peak and Coyote Mountains Wilderness Study Areas, Pima County, Arizona E29 
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 

Subperiod Eocene 

Paleocene 

Cretaceous late 

Early 

late 

Mesozoic 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 

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - (3800l)- - - - - - - - - - - - - - - - - -

pre-Archean2 

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

E30 Mineral Resources of Wilderness Study Areas: Southwestern and South-Central Arizona 

AGE ESTIMATES OF 

BOUNDARIES IN 

MILLION YEARS (Ma) 

0.010 

1.7 

5 

24 

38 

55 

66 

- 96 

138 

205 

-240 

290 

-330 

360 

410 

435 

500 

1

-570 

900 

1600 

2500 

3000 

3400 

4550 
Nowlan; others-MINERAL RESOURCES, BABOQUIVARI PEAK, COYOTE MOUNTAINS WILDERNESS STUUY At<tA::,, At<ILUNA-U.~. uem