U.S. DEPARTMENT OF THE INTERIOR U.S. GEOLOGICAL SURVEY Evaluation of Metallic Mineral Resources and their Geologic Controls in the East Mojave National Scenic Area, San Bernardino County, California by U.S. Geological Survey 1991 Open-File Report 91-427 This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the North American Stratigraphic Code. Any use of trade, product or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. CONTENTS Page Executive summary.................................................................................. 1 Introduction........................................................................................... 2 General geologic setting............................................................................. 5 Proterozoic rocks and their mineralization.........................................................? Early Proterozoic.................................................................................? Middle and Late Proterozoic.................................................................. 10 Granite...................................................................................... 10 Diabase ..................................................................................... 1 1 Evidence of Proterozoic mineralization...................................................... 11 Latest Proterozoic and Paleozoic strata .......................................................... 13 Overview........................................................................................ 13 Summary of rock sequences.................................................................. 14 Mesozoic rocks..................................................................................... 15 Triassic plutons ................................................................................ 1 5 Triassic sedimentary rocks.................................................................... 15 Triassic and(or) Jurassic volcanic and hypabyssal rocks ................................. 15 Jurassic and Cretaceous plutonic rocks: Introduction..................................... 17 Jurassic plutonic rocks.................................................................... 17 Late Jurassic dikes ........................................................................ 18 Cretaceous plutonic rocks................................................................ 19 Terti ary rock s....................................................................................... 21 Introduction..................................................................................... 2 1 Van Winkle Mountain and vicinity...................................................... 2 3 Hackberry Mountain, Woods Mountains, and Wild Horse Mesa................... 2 3 Piute Range, Castle Mountains, and Castle Peaks .................................... 2 4 Cima volcanic field........................................................................ 2 5 Tertiary and Quaternary deposits................................................................. 2 5 Development of pediment domes................................................................. 2 7 Geophysics.......................................................................................... 30 Gravity survey ................................................................................. 31 Magnetic survey................................................................................ 3 2 Discussion of gravity and magnetic anomalies............................................. 3 3 Ivanpah Valley and New York Mountains ............................................. 3 3 Lanfair Valley and Piute Range.......................................................... 3 4 Mid Hills, Providence, and South Providence Mountains ........................... 3 5 Granite Mountains......................................................................... 3 6 Old Dad Mountain and Kelso Mountains............................................... 3 7 Clark Mountain Range.................................................................... 3 8 Woods Mountains Caldera............................................................... 4 0 Aerial gamma-ray surveys.................................................................... 4 0 Landsat Thematic Mapper (TM) surveys....................................................43 Geochemistry....................................................................................... 4 7 RASS, PLUTO, and NURE data bases.....................................................47 Sample types...............................................................................4 8 Evaluation of data ......................................................................... 4 9 Data coverage.............................................................................. 51 Geochemical evaluation...................................................................51 Soda Mountains....................................................................... 5 3 Little Cowhole Mountain.............................................................54 Cowhole Mountain ................................................................... 5 5 Cinder Cone area......................................................................55 Marl Mountains ....................................................................... 5 8 Old Dad Mountain.................................................................... 5 9 Kelso Mountains...................................................................... 61 Bristol Mountains..................................................................... 61 Clark Mountain Range ............................................................... 6 2 Mescal Range..........................................................................6 3 Ivanpah Mountains ................................................................... 6 4 Cima Dome............................................................................ 6 5 New York Mountains ................................................................ 6 6 Mid Hills...............................................................................67 Providence Mountains................................................................67 Granite Moun tains.................................................................... 6 9 Van Winkle Mountain................................................................ 7 0 Grotto Hills............................................................................ 70 Pinto Mountain........................................................................ 7 0 Table Mountain........................................................................71 Woods Mountains .................................................................... 71 Hackberry Mountain.................................................................. 71 Vontrigger Hills....................................................................... 7 3 Piute Range............................................................................ 7 4 Castle Mountains...................................................................... 7 5 Homer Mountain...................................................................... 7 5 U.S. Bureau of Mines data base............................................................. 7 6 Assembly of data base.................................................................... 7 6 Frequency distributions of elements .................................................... 7 8 Nonparametric correlations...............................................................80 Associations using factor analysis.......................................................81 Evaluation of metallic mineral resources in the EMNS A ...................................... 8 4 Introduction..................................................................................... 8 4 Definitions...................................................................................... 8 9 Delineation of areas permissive and favorable for undiscovered metallic mineral resources.......................................................................... 9 2 Proterozoic deposits........................................................................... 9 6 Carbonatite-related, rare-earth element Shonkinite, carbonatite, and associated rock types in the Mountain Pass Area ............................ 9 6 Carbonatite-related, rare-earth element in the EMNSA .............................103 Known occurrences ................................................................103 Permissive terranes .................................................................103 Favorable tracts .....................................................................103 Other types of deposits .................................................................104 Volcanogenic massive sulfide deposits in Arizona and Nevada................104 Volcanogenic massive sulfide deposits in the EMNSA ........................ 104 Granite-related U, Th, and REE deposits in Alaska and elsewhere............105 Granite-related U, Th, and REE deposits in the EMNSA...................... 106 Vein deposits and skarn deposits in the EMNSA ...............................107 Platinum-group occurrences associated with ultramafic rocks in Nevada and Arizona..........................................................................