BULLETIN 84 Geology of the Walnut Wells Quadrangle, Hidalgo County, New Mexico by ROBERT A. ZELLER, JR. and ALLEN M. ALPER 1 9 6 5 STATE BUREAU OF MINES AND MINERAL RESOURCES NEW MEXICO INSTITUTE OF MINING & TECHNOLOGY CAMPUS STATION SOCORRO, NEW MEXICO NEW MEXICO INSTITUTE OF MINING & TECHNOLOGY Stirling A. Colgate, President STATE BUREAU OF MINES AND MINERAL RESOURCES Alvin J. Thompson, Director THE REGENTS MEMBERS Ex OFFICIO The Honorable Jack M. Campbell .................................... Governor of New Mexico Leonard DeLayo .................................................. Superintendent of Public Instruction APPOINTED MEMBERS William G. Abbott .......................................................................................... Hobbs Eugene L. Coulson, M.D. ........................................................................... Socorro Thomas M. Cramer .................................................................................... Carlsbad Eva M. Larrazolo (Mrs. Paul F.) ....................................................... Albuquerque Richard M. Zimmerly ................................................................................... Socorro For sale by the New Mexico Bureau of Mines and Mineral Resources Campus Station, Socorro, N. Mex.—Price $2.50 Contents Page Abs tract ............................................................................................................. 1 Introduction ........................................................................................................ 3 Prior work ...................................................................................................... 6 Present work .................................................................................................. 7 Acknowledgments .......................................................................................... 9 Pre-Tertiary rocks ............................................................................................. 10 Pennsylvanian and Permian Systems ........................................................... 10 Horquilla Limestone ................................................................................. 10 Earp Formation ......................................................................................... 11 Colina Limestone ...................................................................................... 11 Epitaph Dolomite and Scherrer Formation ............................................... 12 Concha Limestone .................................................................................... 13 Cretaceous System ....................................................................................... 13 Hell-to-Finish Formation .......................................................................... 13 U-Bar Formation ....................................................................................... 14 Mojado Formation .................................................................................... 16 Cowboy Spring Formation ........................................................................ 21 Tertiary rocks ................................................................................................... 24 Field and laboratory methods used in study of extrusive rocks . .................. 24 Timberlake Fanglomerate ............................................................................ 27 Horse Hill Breccia ........................................................................................ 31 Bennett Creek Breccia ................................................................................. 31 Oak Creek Tuff ............................................................................................ 33 Basin Creek Tuff .......................................................................................... 36 Page The Animas quartz monzonite porphyry stock ......................................... 38 The Walnut Wells monzonite porphyry plug ............................................. 43 Cedar Hill Andesite ......................................................................................... 46 Young Ranch Tuff .......................................................................................... 47 Bluff Creek Formation ................................................................................... 49 Gillespie Tuff ................................................................................................... 50 Center Peak Latite ........................................................................................... 52 Park Tuff ........................................................................................................... 54 OK Bar Conglomerate ................................................................................... 57 Pine Canyon Formation ................................................................................. 58 Double Adobe Latite ...................................................................................... 60 Quartz latite dikes ........................................................................................... 61 Olivine andesite lenticular intrusion ............................................................. 61 Summary of igneous phases .......................................................................... 62 Quaternary deposits ............................................................................................. 64 Pediment gravel ............................................................................................... 64 Alluvium ........................................................................................................... 64 Zircon petrology .................................................................................................. 65 Structure ................................................................................................................ 67 Winkler anticline .............................................................................................. 67 Periods of deformation .................................................................................. 68 Deformation later than Leonard deposition and earlier than Early Cretaceous deposition ....................................................................... 68 Deformation later than Early Cretaceous deposition and earlier than Tertiary deposition .................................................................. 71 Deformation during Tertiary deposition .................................................. 73 Deformation after Tertiary deposition ..................................................... 78 iv Page Mineral deposits ..................................................................................................... 80 Manganese deposits .......................................................................................... 80 Location .......................................................................................................... 80 Descriptive geology ....................................................................................... 80 Origin ............................................................................................................... 81 Combined Minerals Corporation mine ...................................................... 83 Future exploration ......................................................................................... 83 Other mineral deposits .................................................................................... 83 Red Hill mine ................................................................................................. 83 Gillespie mine ................................................................................................. 88 Fluorite prospects .......................................................................................... 89 Silicification .................................................................................................... 89 Appendix ................................................................................................................. 90 Stratigraphic sections ....................................................................................... 90 Gillespie Creek section ................................................................................. 90 Bennett Creek section ................................................................................... 95 Upper part of Bluff Creek Formation ....................................................... 97 References ............................................................................................................... 98 Index ...................................................................................................................... 101 Illustrations Page PLATES 1. Geologic map of the Walnut Wells quadrangle, New Mexico ............................................................................... In pocket 2. Geologic sections of the Walnut Wells quadrangle, New Mexico ............................................................................... In pocket FIGURES 1. Index map of the Walnut Wells quadrangle .................................... 4 2. Westward view of the Walnut Wells quadrangle ............................ 5 3. Westward view of the Park and Animas Peak ................................. 7 4. Schematic cross section illustrating original relationships of pre-Gillespie Tertiary formations