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E-146, 701 C St. Maps For maps, address mail orders to U.S. Geological Survey, Map Distribution Maps Federal Center, Box 25286 Maps may be purchased over the counter at the U.S. Geologi­ Denver, CO 80225 cal Survey offices where books are sold (all addresses in above list) and at the following Geological Survey offices: Residents of Alaska may order maps from ROLLA, Missouri-1400 Independence Rd. Alaska Distribution Section, U.S. Geological Survey, DENVER, Colorado-Map Distribution, Bldg. 810, Federal New Federal Building - Box 12 Center 101 Twelfth Ave., Fairbanks, AK 99701 FAIRBANKS, Alaska-New Federal Bldg., 101 Twelfth Ave. Chapter D Mineral Resources of the Santa Rosa Mountains Wilderness Study Area, Riverside County, California By J.P. CALZIA, D.J. MADDEN-McGUIRE, and H.W. OLIVER U.S. Geological Survey R.A. SCHREINER U.S. Bureau of Mines U.S. GEOLOGICAL SURVEY BULLETIN 1710 MINERAL RESOURCES OF WILDERNESS STUDY AREAS: SOUTH-CENTRAL CALIFORNIA DESERT CONSERVATION AREA, CALIFORNIA DEPARTMENT OF THE INTERIOR DONALD PAUL MODEL, Secretary U.S. GEOLOGICAL SURVEY Dallas L. Peck, Director Any use of trade names and trademarks in this publication is for descriptive purposes only and does not constitute endorsement by the U.S. Geological Survey UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1988 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 Santa Rosa Mountains Wilderness Study Area, Riverside County, California. (U.S. Geological Survey Bulletin ; 1710-D Bibliography: p. Supt. of Docs. no. : I 19.3:1710-D 1. Mines and mineral resources California Santa Rosa Mountains Wilderness. 2. Santa Rosa Mountains Wilderness (Calif.) I. Calzia, J.P. II. Series. QE75.B9 no. 1710-D 557.3 s 88-600198 [TN24.C2] [553'.09794'97] 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 the Santa Rosa Mountains Wilderness Study Area (CDCA-341), California Desert Conservation Area, Riverside County, California. CONTENTS Summary Dl Abstract 1 Character and setting 1 Mineral resources and mineral resource potential 1 Introduction 1 Location and physiography 2 Previous work 3 Methods 3 Appraisal of identified resources 3 Mining, oil and gas, and geothermal activity 3 Appraisal of sites examined 3 Assessment of mineral resource potential 5 Geology 5 Geochemistry 7 Geophysics 7 Mineral resource potential 8 References cited 8 Appendixes Definition of levels of mineral resource potential and certainty of assessment 12 Resource/reserve classification 13 Geologic time chart 14 PLATE [In pocket] Mineral resource potential map of the Santa Rosa Mountains Wilderness Study Area, Riverside County, California FIGURES 1. Index map showing location of the Santa Rosa Mountains Wilderness Study Area, Riverside County, California D2 2. Map showing mineral resource potential and generalized geology of the Santa Rosa Mountains Wilderness Study Area, Riverside County, California 4 TABLE 1. Mines and prospects in and adjacent to the Santa Rosa Mountains Wilderness Study Area, Riverside County, California D6 Contents MINERAL RESOURCES OF WILDERNESS STUDY AREAS: SOUTH-CENTRAL CALIFORNIA DESERT CONSERVATION AREA, CALIFORNIA Mineral Resources of the Santa Rosa Mountains Wilderness Study Area, Riverside County, California By}.?. Calzia, D.J. Madden-McGuire, and H.W. Oliver U.S. Geological Survey R.A. Schreiner U.S. Bureau of Mines SUMMARY mylonite zone, in the lower plate, include gneiss, schist, marble, and metasedimentary rocks intruded by quartz Abstract monzonite, gabbro, and tonalite of the batholith. The Santa The Santa Rosa Mountains Wilderness Study Area Rosa mylonite zone includes crushed and deformed gneiss, (CDCA-341) covers 68,051 acres in the Santa Rosa Moun­ marble, and tonalite. Rocks structurally above the Santa tains, California. An appraisal of the mineral resources Rosa mylonite zone, in the upper plate, include marble, (known) and an assessment of mineral resource potential gneiss, schist, metasedimentary rocks, and granitic rocks. (undiscovered) of this wilderness study area, hereinafter These upper-plate rocks were thrust westward over the designated "the study area," were made at the request of the mylonite zone along a series of low-angle thrust faults that U.S. Bureau of Land Management and are described in this are spatially and temporally related to the Santa Rosa report. There are no identified mineral resources in the mylonite zone. study area. Geologic, geochemical, geophysical, and min­ eral surveys indicate that the study area has high potential Mineral Resources and Mineral Resource for tungsten and marble resources, moderate potential for Potential gold, and no potential for oil, natural gas, and geothermal Twelve mines, prospects, and mineral occurrences are resources. present in or adjacent to the study area, however there are no identified resources present. Gneiss and schist in the Character and Setting lower plate have high potential for tungsten resources in The Santa Rosa Mountains Wilderness Study Area is skarns. Both upper and lower plates have high resource in mountainous terrain 15 mi south-southeast of Palm potential for marble that may be used in the manufacture of Springs, Calif, (fig. 1). Access to and within the study area Portland cement and for construction materials. Quartz is limited to unmaintained jeep trails and existing foot veins that cut quartz monzonite, gneiss, and schist in the trails. Topographic relief, expressed by steep ridges and lower plate and mylonitic rocks in the upper plate have deep steep-walled canyons, is about 6,200 ft. moderate potential for gold resources. Oil, natural gas, and The geologic setting of the study area is unusual in geothermal resources are not present and there is no poten­ that it sits astride a zone of sheared, pulverized rock known tial for resources of them within the study area. as the Santa Rosa mylonite zone. This mylonite zone was caused by a block of rocks being thrust southwest at about INTRODUCTION the same time as intrusive rocks pushed upward to form the This mineral survey was requested by the U.S. Bu­ Peninsular Ranges batholith. Rocks structurally below the reau of Land Management and is a joint effort by the U.S. Geological Survey and the U.S. Bureau of Mines. An Manuscript approved for publication, June 3, 1988. introduction to the wilderness review process, mineral Mineral Resources of the Santa Rosa Mountains Wilderness Study Area, Riverside County California D1 survey methods, and agency responsibilities were provided cal anomalies, and applicable ore-deposit models. Mineral by Beikman and others (1983).