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Precambrian and Tertiary Geology of Las Tablas Quadrangle, New Mexico

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Precambrian and Tertiary Geology of Las Tablas Quadrangle, New Mexico BULLETIN 45 Precambrian and Tertiary Geology of Las Tablas Quadrangle, New Mexico BY FRED BARKER 1 9 5 8 STATE BUREAU OF MINES AND MINERAL RESOURCES NEW MEXICO INSTITUTE OF MINING & TECHNOLOGY CAMPUS STATION SOCORRO, NEW MEXICO NEW MEXICO INSTITUTE OF MINING & 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 ................................................................................... 4 General statement ................................................................................. 4 Location and access ............................................................................. 4 Physical features .................................................................................. 6 Previous geologic work ........................................................................ 7 Field and laboratory work .................................................................... 8 Acknowledgments ................................................................................ 8 STRATIGRAPHY .................................................................................. 10 Precambrian rocks .............................................................................. 10 General statement ........................................................................... 11 Ortega quartzite .............................................................................. 11 Moppin metavolcanic series ........................................................... 14 Kiawa Mountain formation ............................................................. 24 Big Rock conglomerate member .................................................. 24 Jawbone conglomerate member .................................................. 25 Amphibolite member ................................................................... 25 Upper and lower quartzite members ........................................... 30 Origin of the Ortega quartzite and Kiawa Mountain forma- tion .............................................................................................. 32 Petaca schist ................................................................................... 34 Tertiary rocks ..................................................................................... 36 Previous work ................................................................................ 36 General features ............................................................................. 37 Conejos(?) and Treasure Mountain formations .............................. 37 Treasure Mountain welded tuff ...................................................... 40 Ritito conglomerate ........................................................................ 42 Los Pinos formation ....................................................................... 43 Biscara member ............................................................................ 44 Biscara-Esquibel member ............................................................ 45 Jarita basalt member .................................................................... 46 Cordito member .......................................................................... 48 Origin of the Los Pinos formation ............................................... 50 Santa Fe formation ......................................................................... 51 i i i Page Cisneros basalt ....................................................................................... 51 Dorado basalt ......................................................................................... 53 Quaternary rocks ........................................................................................ 53 Alluvium ................................................................................................. 53 INTRUSIVE IGNEOUS ROCKS .............................................................. 54 Precambrian intrusive rocks ..................................................................... 54 Burned Mountain metarhyolite ........................................................... 54 Maquinita granodiorite ......................................................................... 56 Tres Piedras granite ............................................................................... 59 Pegmatites ............................................................................................... 62 Tertiary intrusive rocks ............................................................................. 64 Biscara intrusive andesite porphyry .................................................... 64 STRUCTURAL GEOLOGY ....................................................................... 65 General features ......................................................................................... 65 Structure of the Precambrian layered rocks ........................................... 65 Kiawa syncline ....................................................................................... 65 Hopewell anticline ................................................................................. 66 Poso anticline ......................................................................................... 67 Big Rock syncline .................................................................................. 68 General discussion ................................................................................ 68 Structure of the Tusas Valley and Vallecitos Valley fault zones 71 General statement ................................................................................. 71 Tusas Valley fault zone ......................................................................... 72 Vallecitos Valley fault zone .................................................................. 72 Other faults ............................................................................................ 73 Structure of the Tertiary rocks ................................................................ 73 METAMORPHISM ....................................................................................... 74 General statement ...................................................................................... 74 General discussion of regional metamorphism ................................ 74 Regional metamorphism ........................................................................... 79 General features ...................................................................................... 79 Metamorphism of the basaltic rocks .................................................. 80 Metamorphism of pelitic schists ......................................................... 84 Genesis of kyanite in the Ortega quartzite and Kiawa Moun- tain formation ..................................................................................... 84 Metamorphism of the Burned Mountain metarhyolite ................... 85 Relationship between folding and regional metamorphism ........... 86 Relationship between regional metamorphism and plutonic rocks ..................................................................................................... 86 iv Page Pegmatitic-hydrothermal metamorphism .................................................. 87 General features .................................................................................. 87 Metasomatism of the quartz-feldspar rocks ........................................ 87 Metasomatism of amphibolite ............................................................. 89 General discussion of pegmatitic-hydrothermal metamor- phism ................................................................................................ 93 Relation of pegmatitic-hydrothermal metamorphism to re- gional metamorphism ....................................................................... 95 Formation of the bodies of quartz-kyanite rock at La Jarita Mesa ................................................................................................. 95 GEOLOGIC HISTORY .............................................................................. 98 REFERENCES ............................................................................................ 99 INDEX ....................................................................................................... 101 Illustrations TABLES 1. Generalized stratigraphic section of the Tertiary in Las Tablas quadrangle ................................................................................. 3 2. Precambrian stratified rocks of Las Tablas quadrangle ..................... 10 3. Chemical analyses of metamorphic rocks in Las Tablas quad- rangle .................................................................................................
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