BULLETIN 57 Geology of the Central Peloncillo Mountains, Hidalgo County, New Mexico, and Cochise County, Arizona by ELLIOT GILLERMAN 1958 STATE BUREAU OF MINES AND MINERAL RESOURCES NEW MEXICO INSTITUTE OF MINING & TECHNOLOGY CAMPUS STATION SOCORRO, NEW MEXICO NEW MEXICO INSTITUTE OF MINING 8c TECHNOLOGY E. J. Workman, President STATE BUREAU OF MINES AND MINERAL RESOURCES Alvin J. Thompson, Director THE REGENTS MEMBERS Ex OFFICIO The Honorable Edwin L. Mechem ....................... Governor of New Mexico Mrs. Georgia L. Lusk ...............................Superintendent of Public Instruction APPOINTED MEMBERS Robert W. Botts ...................................................................... Albuquerque Holm 0. Bursum, Jr. ........................................................................ Socorro Thomas M. Cramer ........................................................................ Carlsbad John N. Mathews, Jr. ....................................................................... Socorro Richard A. Matuszeski ............................................................ Albuquerque Contents Page ABSTRACT ........................................................................................................ 1 INTRODUCTION .......................................................................................... 2 Scope and purpose ......................................................................................... 2 Methods ........................................................................................................... 2 Geography ....................................................................................................... 3 Physiography ................................................................................................... 3 Climate and vegetation .................................................................................. 5 Previous work ................................................................................................. 6 Acknowledgments ......................................................................................... 7 GEOLOGY ....................................................................................................... 9 Intrusive igneous rocks ................................................................................. 9 Granite Gap granite .................................................................................. 9 Cienega Peak granite ...............................................................................12 Quartz monzonite porphyry ................................................................. 13 Latite porphyry ........................................................................................15 Minor intrusive rocks ..............................................................................17 Layered rocks ................................................................................................18 Bolsa quartzite ..........................................................................................18 El Paso limestone ....................................................................................21 Montoya limestone ................................................................................. 24 Percha shale ............................................................................................. 25 Escabrosa limestone ............................................................................... 28 Paradise formation ................................................................................. 29 Naco group .............................................................................................. 31 Horquilla limestone ............................................................................31 Earp formation ................................................................................... 35 Colina limestone ..................................................................................38 Scherrer formation ............................................................................. 39 Chiricahua limestone ......................................................................... 41 Bisbee group ............................................................................................ 43 McGhee Peak formation ................................................................... 45 Carbonate Hill limestone .................................................................. 47 Still Ridge formation .......................................................................... 50 Johnny Bull sandstone ....................................................................... 52 Volcanic sequence .................................................................................. 53 Quartz latite .........................................................................................53 Bobcat Hill conglomerate ................................................................. 55 Andesite ............................................................................................... 58 Quarry Peak rhyolite complex ......................................................... 65 iii Page Basalt .................................................................................................... 68 Steins Mountain quartz latite porphyry ........................................... 69 Vanar Hills volcanic rocks ................................................................ 69 Weatherby Canyon ignimbrite .......................................................... 70 Alluvial and lacustrine deposits ............................................................ 75 Older alluvium .................................................................................... 75 Lake beds and beach deposits .......................................................... 75 Younger alluvium ............................................................................... 76 Animas Valley basalt ............................................................................... 77 Structure ...................................................................................................... 78 Peloncillo arch, northwest-trending faults, and drag folds 78 Granite Gap and Preacher Mountain faults ....................................... 80 Northeast faults ....................................................................................... 81 Late Tertiary and Quaternary faults ..................................................... 81 Recent faults ............................................................................................ 82 Form of igneous intrusive bodics ........................................................ 82 Metamorphism ........................................................................................... 84 Geologic history ......................................................................................... 88 MINERAL DEPOSITS ................................................................................ 93 Copper, lead, zinc, and silver deposits ................................................... 95 Carbonate Hill mine ............................................................................... 95 Silver Hill mine ........................................................................................ 97 Johnny Bull mine .................................................................................... 99 Duke and other claims ......................................................................... 100 Granite Gap mines ............................................................................... 101 Deposits east and south of Granite Gap .......................................... 102 Crystal mine ........................................................................................... 103 Mineral Mountain mine ....................................................................... 103 Charles mine .......................................................................................... 104 Other deposits ....................................................................................... 104 Tungsten deposits .................................................................................... 104 Fluorite deposits ....................................................................................... 105 MEASURED SECTIONS ......................................................................... 106 Bolsa quartzite .......................................................................................... 106 El Paso limestone ..................................................................................... 108 Percha shale .............................................................................................. 109 Escabrosa limestone ................................................................................ 109 Paradise formation ................................................................................... 112 Paradise formation ................................................................................... 113 Horquilla limestone ................................................................................. 118 Horquilla limestone ................................................................................. 119 Earp formation ......................................................................................... 121 Colina limestone ......................................................................................