Mineral Resources of the Newberry Mountains and Rod Man Mountains
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Mineral Resources of the Newberry Mountains and Rod man Mountains Wilderness Study/ Areas,f San Bernardino County, California U.S. GEOLOGICAL SURVEY BULLETIN 1712-A Chapter A Mineral Resources of the Newberry Mountains and Rodman Mountains Wilderness Study Areas, San Bernardino County, California By BRETT F. COX, ANDREW GRISCOM, JAMES E. KILBURN, GARY L. RAINES, and DANIEL H. KNEPPER, Jr. U.S. Geological Survey CHARLES SABINE and LUCIA KUIZON U.S. Bureau of Mines U.S. GEOLOGICAL SURVEY BULLETIN 1712 MINERAL RESOURCES OF WILDERNESS STUDY AREAS: CENTRAL CALIFORNIA DESERT CONSERVATION AREA 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 Newberry Mountains and Rodman Mountains Wilderness Study Areas, San Bernardino County, California. U.S. Geological Survey Bulletin B-1712-A Bibliography Supt. of Docs. No.: I 19.3:1712-A 1. Mines and mineral resources California Newberry Mountains Wilderness. 2. Mines and mineral resources California Rodman Mountains Wilderness. 3. Geology California Newberry Mountains Wilderness. 4. Geology California Rodman Mountains Wilderness. 5. Newberry Mountains Wilderness (Calif.) 6. Rodman Mountains Wilderness (Calif.) I. Cox, Brett F. II. Series. QE75.B9 No. 1712-A 557.3 s 87-600015 [TN24.C2] [553'.09794'95] STUDIES RELATED TO WILDERNESS Bureau of Land Managment Wilderness Study Areas The Federal Land Policy and Management Act (Public Law 94-579, October 21, 1976) requires the U.S. Geological Survey and the U.S. Bureau of Mines to conduct mineral surveys of certain areas to determine the mineral values, if any, that may be present. Results must be made available to the public and be submitted to the President and the Congress. This report presents the results of a mineral survey of parts of the Newberry Mountains (CDCA-206) and Rodman Mountains (CDCA-207) Wilderness Study Areas, California Desert Conservation Area, San Bernardino County, California. CONTENTS Summary Al Abstract 1 Character and setting 1 Mineral resources and potential for undiscovered resources 3 Newberry Mountains Wilderness Study Area 3 Rodman Mountains Wilderness Study Area 3 Introduction 3 Location and physiography 3 Previous studies 6 Procedures and sources of data 6 Acknowledgments 6 Appraisal of identified resources 8 Field work and analytical methods 8 Regional history of mining and mineral exploration 8 Sites examined for this study 8 Newberry Mountains Wilderness Study Area 8 Rodman Mountains Wilderness Study Area 11 Conclusions 11 Assessment of mineral resource potential 11 Geology 11 Rock units 11 Geologic structure 13 Rock alteration and veins 14 Geochemical studies 17 Methods 17 Summary of results 17 Newberry Mountains Wilderness Study Area 17 Rodman Mountains Wilderness Study Area 18 Geophysical studies 19 Gravity survey 19 Aeromagnetic survey 19 Conclusions 22 General summary 22 Mineral resource potential of the Newberry Mountains Wilderness Study Area 23 Mineral resource potential of the Rodman Mountains Wilderness Study Area 23 References cited 24 Appendix 1. Definition of levels of mineral resource potential and certainty of assessment 27 Geologic Time Chart 28 FIGURES 1. Index map showing location of the Newberry Mountains and Rodman Mountains Wilderness Study Areas A2 2. Map showing geology and mineral resource potential of the Newberry Mountains and Rodman Mountains Wilderness Study Areas 4 3. Map showing areas of altered rocks in the Newberry Mountains and Rodman Mountains Wilderness Study Areas 7 4. Map showing geochemical sample sites and geochemical anomalies in the Newberry Mountains and Rodman Mountains Wilderness Study Areas 15 5. Isostatic residual gravity map of the Newberry Mountains and Rodman Mountains Wilderness Study Areas 20 6. Map showing aeromagnetic interpretation of the Newberry Mountains and Rodman Mountains Wilderness Study Areas 21 7. Major elements of mineral resource potential/certainty classification 27 TABLES 1. Mines and prospects in and adjacent to the Newberry Mountains Wilderness Study Area 9 2. Mines, prospects, and mineralized sites in and adjacent to the Rodman Mountains Wilderness Study Area 10 MINERAL RESOURCES OF WILDERNESS STUDY AREAS: CENTRAL CALIFORNIA DESERT CONSERVATION AREA Mineral Resources of the Newberry Mountains and Rodman Mountains Wilderness Study Areas, San Bernardino County, California By Brett F. Cox, Andrew Griscom, James E. Kilburn,Gary L. Raines, and Daniel H.Knepper, Jr U.S. Geological Survey and Charles Sabine and Lucia Kuizon U.S. Bureau of Mines SUMMARY Character and Setting Abstract The Newberry Mountains and Rodman Mountains Wilderness Study Areas lie adjacent to one another in The Newberry Mountains (CDCA-206) and the Mojave Desert of southeastern California (fig. 1). Rodman Mountains (CDCA-207) Wilderness Study Both study areas are rugged and dry, consisting of Areas occupy adjacent mountain ranges in the central sparsely vegetated ridges and steep-walled canyons Mojave Desert, 10 to 30 mi southeast of Barstow, occupied by sandy washes. The canyons open onto Calif. The parts of the two study areas on which large alluvial fans along the northern margins of the mineral surveys were requested encompass study areas. The 1-mi gap between the study areas is approximately 27,964 acres and 16,900 acres, occupied by the large northeast-trending canyon of respectively. Fieldwork conducted between 1983 and Kane Wash. 1985 included geologic, geochemical, and geophysical Both study areas are underlain by Mesozoic ( 240 studies by the U.S. Geological Survey and a survey of to 63 million years before present, or Ma; see Geologic mines, prospects, and mineralized areas by the U.S. Time Chart, last page of this report) plutonic rocks, by Bureau of Mines. There are no currently or formerly a diverse assemblage of earliest Miocene productive mineral deposits inside either study area. (approximately 24 to 20 Ma) intrusive, extrusive, and However, despite the lack of identified mineral sedimentary rocks, and by Quaternary alluvium. The resources, both study areas have localized potential Newberry Mountains Wilderness Study Area is for undiscovered resources, as discussed below. underlain predominantly by Miocene volcanic and The Newberry Mountains Wilderness Study Area sedimentary strata, which surround several hills of contains two areas with mineral resource potential. Mesozoic plutonic rocks. The plutonic rocks locally (See appendix 1 for definitions of levels of mineral contain small pendants of Mesozoifc metavolcanic resource potential.) There is moderate potential for rocks. The plutonic rocks and the Miocene strata are undiscovered epithermal gold and silver deposits in a intruded by volcanic dikes of rhyolitic to intermediate zone crossing the west margin of the study area, and composition, located mostly in the eastern part of the there is moderate potential for undiscovered Newberry Mountains Wilderness Study Area. epithermal silver deposits at the east end of the study The belt of Miocene strata and associated area. intrusive rocks continues east of Kane Wash where it The Rodman Mountains Wilderness Study Area underlies the northern and northeastern parts of the contains three areas with mineral resource potential. Rodman Mountains Wilderness Study Area. The There is moderate potential for undiscovered small- southern two-thirds of the study area is underlain scale vein deposits of gold, silver, and copper in two primarily by Mesozoic plutonic rocks. Miocene areas in the southwestern and north-central parts of conglomerate and Pleistocene (approximately 0.6 Ma) the study area, and there is low potential for basalt depositionally overlie the plutonic rocks in the undiscovered placer gold in a small area near the central and northwestern parts of the study area. northeast corner of the study area. The Miocene rocks in both study areas were In this report, any references to the "wilderness strongly faulted and tilted moderately toward the study area" or the "study area" refe* only to that part southwest during intense regional northeast extension of the wilderness study area designated by the U.S. that was contemporaneous with early Miocene Bureau of Land Management as suitable for mineral volcanism and sedimentation. Granitic rocks exposed surveys. along the north flank of the Newberry Mountains were Al Daggett NEWBERRY MOUNTAINS WILDERNESS STUDY AREA (CDCA-206) RODMAN MOUNTAINS ,, WILDERNESS STUDY/u^-H AREA (CDCA-207) \^ ) Lavic Dry SIDEWINDER MOUNTAIN / \ Emerson MelvilleX ) k VDry Lake Dry Lake K \^ ^ 1. Index map showing location of the Newberry Mountains and Rodman Mountains Wilderness Study Areas. A2 strongly crushed and sheared during this extensional potential for undiscovered mineral resources. In terms episode. Subsequent deformation of the region after of geologic setting, rock alteration, and geochemical early Miocene time has resulted from right-lateral anomalies, this area is similar to mineralized areas of movements along the Camp Rock and Calico faults the Calico Mountains to the northwest, where silver is (fig. 2). found in barite-rich veins associated with Miocene Mining and prospecting within the central Mojave intrusive rocks and potassium-feldspar alteration. Desert region have occurred intermittently since the 1860's. There is no record