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Isotopic Ages of Post-Paleocene Igneous Rocks Within and Bordering the Clifton 1° X 2° Quadrangle, Arizona—New Mexico

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Isotopic Ages of Post-Paleocene Igneous Rocks Within and Bordering the Clifton 1° X 2° Quadrangle, Arizona—New Mexico New Mexico Bureau of Mines & Mineral Resources A DIVISION OF NEW MEXICO INSTITUTE OF MINING & TECHNOLOGY Isotopic ages of post-Paleocene igneous rocks within and bordering the Clifton 1° x 2° quadrangle, Arizona—New Mexico by R. F. Marvin¹, C. W. Naeser¹, M. Bikerman2, H. H. Mehnert¹, and J. C. Ratté¹ ¹U.S. Geological Survey, Denver, Colorado 80225; 'Department of Geology and Planetary Science, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 SOCORRO 1987 11 NEW MEXICO INSTITUTE OF MINING & TECHNOLOGY Laurence H. Lattman, President NEW MEXICO BUREAU OF MINES & MINERAL RESOURCES Frank E. Kottlowski, Director George S. Austin, Deputy Director BOARD OF REGENTS Ex Officio Garrey E. Carruthers, Governor of New Mexico Alan Morgan, Superintendent of Public Instruction Appointed Gilbert L. Cano, President, 1985-1989, Albuquerque Lenton Malry, Sec./Treas., 1985-1991, Albuquerque Robert 0. Anderson, 1987-1993, Roswell Donald W. Morris, 1983-1989, Los Alamos Steve Torres, 1967-1991, Albuquerque BUREAU STAFF Full Time ORIN J. ANDERSON, Geologist DARRELL DAUDE, Computer Operator BARBARA R. POPP, Biotechnologist RUBEN ARCHULETA, Technician II Lois M. DEVLIN, Director, Bus./Pub. Office IREAN L. RAE, Drafter AL BACA, Crafts Technician ROBERT W. EVELETH, Mining Engineer MARSHALL A. REITER, Senior Geophysicist NORMA L. BACA, Secretary/Receptionist ROUSSEAU H. FLOWER, Emeritus Sr. Paleontologist JACQUES R. RENAULT, Senior Geologist JAMES M. BARKER, Industrial Minerals Geologist MICHAEL J. HARRIS, Metallurgist JAMES M. ROBERTSON, Senior Economic Geologist ROBERT A. BIEBERMAN, Senior Petrol. Geologist JOHN W. HAWLEY, Senior Env. Geologist GRETCHEN H. ROYBAL, Coal Geologist DANNY BORROW, Geologist CAROL A. HJELLMING, Editorial Secretary DEBORAH A. SHAW, Assistant Editor LYNN A. BRANDVOLD, Senior Chemist GARY D. JOHNPEER, Engineering Geologist WILLIAM J. STONE, Senior Hydrogeologist RON BROADHEAD, Petroleum Geologist ANNABELLE LOPEZ, Staff Secretary SAMUEL THOMPSON III, Senior Petrol. Geologist MONTE M. BROWN, Drafter DAVID W. LOVE, Environmental Geologist REBECCA J. TITUS, Drafter FRANK CAMPBELL, Coal Geologist JANE A. CALVERT LOVE, Associate Editor JUDY M. VAIZA, Executive Secretary ANNETTE G. CARROLL, Admin. Secretary I CECILIA ROSACKER MCCORD, Technician I MANUEL J. VASQUEZ, Mechanic STEVEN M. CATHER, Postdoctoral Fellow CHRISTOPHER G. MCKEE, X-ray Laboratory Technician ROBERT H. WEBER, Emeritus Senior Geologist RICHARD CHAMBERLIN, Economic Geologist VIRGINIA MCLEMORE, Geologist DONALD WOLBERG, Vertebrate Paleontologist CHARLES E. CHAPIN, Senior Geologist LYNNE MCNEIL, Technical Secretary ZANA G. WOLF, Staff Secretary RICHARD R. CHAVEZ, Assistant Head, Petroleum NORMA J. MEEKS, Accounting Clerk—Bureau MICHAEL W. WOOLDRIDGE, Chief Sci. Illustrator RUBEN A. CRESPIN, Garage Supervisor ROBERT M. NORTH, Economic Geologist–Mineralogist JIRI ZIDEK, Chief Editor–Geologist Research Associates CHRISTINA L. BALK, NMT JEFFREY A. GRAMBLING, UNM JOHN R. MACMILLAN, NMT WILLIAM L. CHENOWETH, Grand Junction, CO JOSEPH HARTMAN, Univ. Minn. HOWARD B. NICKELSON, Carlsbad PAIGE W. CHRISTIANSEN, Kitty Hawk, NC DONALD E. HATTIN, Ind. Univ. LLOYD C. PRAY, Univ. Wisc. RUSSELL E. CLEMONS, NMSU ALONZO D. JACKA, Texas Tech. Univ. ALLAN R. SANFORD, NMT WILLIAM A. COBBAN, USGS DAVID B. JOHNSON, NMT JOHN H. SCHILLING, Nev. Bur. Mines & Geology AUREAL T. CROSS, Mich. St. Univ. WILLIAM E. KING, NMSU WILLIAM R. SEAGER, NMSU MARIAN GALUSHA, Amer. Mus. Nat. Hist. DAVID V. LEMONS, UTEP RICHARD H. TEDFORD, Amer. Mus. Nat. Hist. LELAND H. GILE, Las Cruces A. BYRON LEONARD, Kansas Univ. JORGE C. TOVAR R., Petroleos Mexicanos Graduate Students MARGARET BARROLL RICHARD HARRISON RICHARD P. LOZINSKY DIANE BELLIS TIM HOBBS WILLIAM MCINTOSH JOAN GABELMAN DAVID L. JORDAN Plus about 50 undergraduate assistants Original Printing 1987 Published by Authority of State of New Mexico, NMSA 1953 Sec. 63-1-4 Printed by University of New Mexico Printing Plant, December 1987 Available from New Mexico Bureau of Mines & Mineral Resources, Socorro, NM 87801 111 Contents ABSTRACT 5 INTRODUCTION 5 PRESENT STUDY 5 ACKNOWLEDGMENTS 5 ORGANIZATION OF COMPILATION 5 DISCUSSION 13 COMPARATIVE AGE DATA FOR BLOODGOOD CANYON AND APACHE SPRING TUFFS 14 VOLCANO-STRATIGRAPHIC CORRELATIONS 16 FLOW-BANDED RHYOLITES OF THE CENTRAL AND WESTERN PARTS OF THE MOGOLLON-DATIL VOLCANIC FIELD 17 BEARWALLOW MOUNTAIN FORMATION REDEFINED AND REVISED 21 MIOCENE VOLCANISM ALONG THE MORENCI-RESERVE FAULT ZONE 23 ISOTOPIC-AGE COMPILATION 30 REFERENCES 61 Tables 1—List of age-data entries in numerical order according to their location by 71/2- and 15-min quadrangles 7 2-40Ar/39Ar ages of some major ash-flow tuffs 13 3—Ages of Bloodgood Canyon and Apache Spring Tuffs 15 4—Ages of flow-banded rhyolites 18 5—Ages of Bearwallow Mountain Andesite 20 6—Ages of basaltic lava flows and silicic volcanic rocks here excluded from the Bearwallow Mountain Andesite 21 7—Ages of post-Bearwallow Mountain Andesite volcanic rocks along Morenci—Reserve fault zone 22 8—List of age-data entries in approximate order of increasing age based on both ages and geologic data 24 9—Fission-track data for sphenes from four samples of Apache Spring Tuff, Bursum caldera 41 10—Fission-track data for zircons from five samples of Bloodgood Canyon Tuff, Steeple Rock quadrangle 56 Figures 1—Location of dated samples bordering the Clifton 1° x 2° quadrangle 6 2—Histogram of Bloodgood Canyon Tuff ages 14 3—Distribution and correlation of some major ash-flow tuffs 16 4—Histograms of flow-banded rhyolite ages 19 5—Histogram of ages of volcanic rocks between 10 and 21 m. y. in the Morenci—Reserve fault zone 23 Plate 1—Location of dated samples in the Clifton 1° x 2° quadrangle, Arizona—New Mexico (in back pocket) 5 Abstract This report is a compilation of isotopic ages and analytical data from more than 200 samples of volcanic and subvolcanic igneous rocks of the western and central parts of the Mogollon—Datil volcanic field of middle to late Cenozoic age. More than one-half of the tabulated ages have never been published. In addition to the compilation of ages, the report includes brief discussions of some of the problems involved in conventional K—Ar and fission-track dating of rapidly erupted volcanic sequences in a large, complex volcanic field and includes some of the specific volcano-stratigraphic problems in the central and western parts of the Mogollon—Datil field. Introduction In recent years, numerous K—Ar and fission-track ages have been determined for volcanic rocks of the Acknowledgments Mogollon—Datil volcanic field. Most of these dated Ages and analytical data previously published by rocks were collected within or peripheral to the Clif- workers other than the authors comprise nearly 20% ton 1° x 2° quadrangle of Arizona and New Mexico. of the compilation. P. E. Damon, M. Shafiqullah, and However, the Clifton quadrangle encompasses only D. York are the major contributors of published ages and part of the Mogollon—Datil volcanic field. analytical data for rocks collected by R. C. Rhodes, This compilation of isotopic ages lists more than 200 E. I. Smith, R. V. Fodor, T. J. Bornhorst, W. E. samples of post-Paleocene igneous rocks. Slightly more Elston, and others. V. A. Lawrence, M. R. Oakman, than one-half of the tabulated ages have never been W. E. Brooks, and E. Rivera assisted in various published. Also included in this compilation are aspects of field and laboratory work and manuscript unpublished analytical data pertaining to tabulated ages preparation. that have already appeared in print. M. Bikerman acknowledges support from the New The purposes of this compilation are: Mexico Bureau of Mines and Mineral Resources for field work in western New Mexico. This is 1) to present the currently available age data that publication no. 665 of the Department of Geology and are pertinent to establishment of viable vol- Planetary Science, University of Pittsburgh, canic stratigraphic sequences in the western Pittsburgh, Pennsylvania. and central parts of the Mogollon—Datil vol- canic field. We have profited from the informal cooperation of the New Mexico Bureau of Mines and Mineral Re- 2) to describe some of the problems associated with sources, particularly through numerous field excursions dating the rocks of a complex volcanic field and with C. E. Chapin, G. R. Osburn, W. C. McIntosh, and the efficacy of different radiometric dating S. M. Cather. Paleomagnetic studies and preci- methods. sion 40Ar/39Ar dating, presently in progress by W. C. 3) to discuss the application of the ages in the McIntosh, have been shared freely with us and promise compilation to certain specific geologic problems to provide important new dimensions toward es- in the western and central parts of the tablishing a volcanic stratigraphic framework for the Mogollon—Datil field. Mogollon—Datil volcanic field. The manuscript was greatly improved by the very thorough editing of Jane Calvert Love, Associate Editor, New Mexico Bureau of Present study Mines and Mineral Resources. Approximately 70% of the ages and analytical data in the compilation are the work of Marvin, Naeser, and Mehnert in the U.S. Geological Survey laboratories in Organization of compilation Denver, Colorado, since about 1972, and about 12% are the work of Bikerman at the University of The compilation consists basically of separate en- Pittsburgh, over roughly the same period. Some of the tries of descriptive and analytical data for more than U.S. Geological Survey samples were collected by T. 200 rock samples. From this body of data, two master L. Finnell, D. C. Hedlund, W. E. Brooks, and B. B. lists were made, Tables 1 and 8; both lists give the Houser, but most were collected by Ratté. Biker-man, same information: entry number, name or correlation, Marvin, and Mehnert are responsible for the age(s), and quadrangle location. In Table 1, the conventional K—Ar age determinations and interpre- samples are listed in numerical sequence by entry tation of the analytical data; Naeser is responsible for number, according to their location in 71/2- and 15- the fission-track ages and analyses; Ratté is largely min quadrangles, whereas in Table 8 (pp.
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