Mineral Resources of the Southern Inyo Wilderness Study Area, Inyo County, California U.S. GEOLOGICAL SURVEY BULLETIN 1705-B Chapter B Mineral Resources of the Southern Inyo Wilderness Study Area, Inyo County, California By JAMES E. CONRAD, JAMES E. KILBURN, and RICHARD J.BLAKELY U.S. Geological Survey CHARLES SABINE, ERIC E. GATHER, LUCIA KUIZON, and MICHAEL C.HORN U.S. Bureau of Mines U.S. GEOLOGICAL SURVEY BULLETIN 1705 MINERAL RESOURCES OF WILDERNESS STUDY AREAS: SOUTH-CENTRAL CALIFORNIA DEPARTMENT OF THE INTERIOR DONALD PAUL MODEL, Secretary U.S. GEOLOGICAL SURVEY Dallas L. Peck, Director UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1987 For sale by the Books and Open-File Reports Section U.S. Geological Survey Federal Center, Box 25425 Denver, CO 80225 Library of Congress Cataloging-in-Publication Data Mineral resources of the Southern Inyo Wilderness Study Area, Inyo County, California. U.S. Geological Survey Bulletin 1705-B Bibliography Supt. of Docs. No.: I 19.3:1705-6 1. Mines and mineral resources California Southern Inyo Wilderness. I. Conrad, James E. II. Series. QE75.B9 No. 1705-B 557.3 s 87-600133 [TN24.C2] [553'.09794'87] STUDIES RELATED TO WILDERNESS Bureau of Land Management Wilderness Study Area The Federal Land Policy and Management Act (Public Law 94-579, October 21,1976) requires the U.S. Geological Survey and the U.S. Bureau of Mines to conduct mineral surveys on certain areas to determine the mineral values, if any, that may be present. Results must be made available to the public and be submitted to the President and the Congress. This report presents the results of a mineral survey of part of the Southern Inyo Wilderness Study Area (CA- 010-056), Inyo County, California. CONTENTS Summary Bl Abstract 1 Character and setting 1 Mineral resources 1 Mineral resource potential 2 Introduction 3 Area description 3 Previous and present investigations 3 Appraisal of identified resources 5 History and production 5 Mineral resources 6 Assessment of mineral resource potential 7 Geology 7 Geochemical studies 7 Geophysical studies 8 Mineral resource potential 9 References cited 10 Appendixes Definition of levels of mineral resource potential and certainty of assessment Geologic time chart Summary of mines and prospects in and adjacent to the Southern Inyo Wilderness Study Area, Inyo County, California PLATE In pocket 1. Mineral resource potential map of the Southern Inyo Wilderness Study Area, Inyo County, California FIGURES 1. Index map showing location of the Southern Inyo Wilderness Study Area, Inyo County, California B2 2. Map showing mineral resource potential and generalized geology of the Southern Inyo Wilderness Study Area, Inyo County, California 4 MINERAL RESOURCES OF WILDERNESS STUDY AREAS: SOUTH-CENTRAL CALIFORNIA Mineral Resources of the Southern Inyo Wilderness Study Area, Inyo County, California By James E. Conrad, James E. Kilburn, and Richard J. Blakely U.S. Geological Survey Charles Sabine, Eric E. Gather, Lucia Kuizon, and Michael C. Horn U.S. Bureau of Mines SUMMARY Character and Setting Abstract The Southern Inyo Wilderness Study Area lies in the southern part of the Inyo Mountains about 5 mi east of Mineral surveys were requested on part of the Lone Pine, Calif, (fig. 1). The northern part of the study Southern Inyo Wilderness Study Area (CA-010-056) covering area is very steep and rugged with relief as much as 7,400 27,240 acres on the west side of the southern Inyo ft; the southeastern part of the area is less rugged but also Mountains. In this report, the area studied is referred to as contains numerous steep and inaccessible canyons. A "the wilderness study area", or simply "the study area". Fieldwork for this report was carried out between 1983 and sequence of intensely folded and faulted marine sedimentary 1985. No resources were identified at the 66 mines and rocks of Cambrian through Triassic age (570-205 million prospects examined in and adjacent to the study area. years before present (Ma); see appendix for geologic time Several areas have low and moderate resource potential for chart) and continental volcanic and sedimentary rocks of gold, silver, lead, and zinc. A zone extending from the Triassic age (240-205 Ma) underlie the area. Limestone and Reward mine (near the northwest corner of the study area) 3 dolomite are the most abundant rock types in the lower part mi to the southeast has low and moderate resource potential of the marine sequence; shale is more abundant in the upper for gold, silver, lead, and zinc. There is low potential for gold, part. These rocks are intruded by a number of plutons and silver, lead, and zinc resources in an area located about 1.5 small granitic bodies of Jurassic and Cretaceous (205-63 mi northeast of the Reward mine. A mineralized shear zone Ma) age. Faulting, folding, and metamorphism have on the north side of Union Wash, about 3 mi south of the greatly deformed the stratified rocks, especially near the Reward mine, has moderate resource potential for silver and large plutons. lead on the west and low resource potential for gold, silver, lead, and zinc on the east. Two areas between Kern Knob and Dolomite Canyon along the southwest boundary of the study area and the south edge of the study area have low Mineral Resources resource potential for silver, lead, and zinc. Low resource potential for gold, silver, lead, and zinc is indicated for the Mining activity has been intermittent in this part of southwest flank of New York Butte on the east edge of the the Inyo Mountains for more than 100 years. The Russ study area. There is low resource potential for talc in the area mining district, organized in 1860, covers nearly the entire east of Kern Knob. study area. The discovery of high-grade silver ore in 1865 Bl at the Cerro Gordo mine, located about 5 mi southeast of Mineral Resource Potential the study area, attracted thousands of miners and pros­ pectors to the area. The Inyo Mountains are among the The Southern Inyo Wilderness Study Area lies most heavily prospected areas in the western United States within a province characterized by hydrothermal deposits of and probably more than 1,000 mining claims have been gold, silver, lead, and zinc. Most large deposits in the located in the study area. However, only sporadic mining region, such as that at the Cerro Gordo mine (fig. 1), are activity has occurred during the twentieth century, mostly found in carbonate rock as veins, stockworks, or bedded during the two world wars and the great depression, and replacement bodies. Small but rich gold- and silver-bearing virtually no mining has been recorded since the early veins can be present in all rock types but generally are 1950's. concentrated in or near the large granitic plutons. 1 I8°00' 1 I7°45' 36°45' SOUTHERN INYO WILDERNESS STUDY AREA (CA-010-056) V O 36°30' "x_CALIF AREA OF MAP Figure 1. Index map showing location of the Southern Inyo Wilderness Study Area, Inyo County, California B2 The geology of the study area is also conducive to Lush grasses and many varieties of wildflowers also are the formation of skarns, which form in carbonate rocks present. adjacent to large plutons. Anomalous concentrations of Access within the area is limited to foot trails built elements such as tungsten, molybdenum, and bismuth that by prospectors in the 1870's and 1930's. Numerous graded are associated with skarns and the heavy minerals scheelite dirt roads in Owens Valley provide access to the western and pyrite were identified in geochemical samples from the part of the study area and lead to canyons and mines along study area and indicate this type of mineralization. Only the base of the range including Union Wash, Long John small skarn deposits are known to exist in the study area, Canyon, Brooklyn Canyon, Dolomite Canyon, and the however. Talc is another type of deposit related to the Reward mine. A jeep trail, passable in four-wheel drive, contact-metamorphic effects of the large granitic plutons runs from Swansea to the Burgess mine along the southeast found in the study area. Small talc bodies were mined in boundary and provides access to the southeastern part of the and near the study area in the vicinity of Kern Knob (fig. study area. 2). There is low resource potential for talc east of Kern Knob. Geochemical and mineralogical evidence and an inventory of mines and prospects indicate that gold, silver, Previous and Present Investigations lead, and zinc mineralization has occurred in several places in the study area. Many of the mines and prospects The Southern Inyo Wilderness Study Area includes examined in this study lie within these mineralized areas, parts of the New York Butte, Lone Pine, and Independence although none have identified resources. A zone extending 15-minute quadrangles. Geologic studies of this area began from the Reward mine area 3 mi to the southeast has low with those of Knopf (1914, 1918) and Kirk (in Knopf, resource potential for gold, silver, lead, and zinc, and the 1918), who described the stratigraphy and published immediate vicinity of the Reward mine has moderate reconnaissance geologic maps of parts of the range. A resource potential for these elements (fig. 2). An area of study of the mineral deposits by Merriam (1963) at the fissure veins in granitic rocks about 1.5 mi northeast of the Cerro Gordo mine, located 5 mi east of the study area, Reward mine has low potential for gold, silver, lead, and included a reconnaissance map of the southern part of the zinc resources. An east-trending shear zone on the north Inyo Mountains.