CONTENTS Foreword Memorial to Rodney Charles Rhodes 1 REGIONAL GEOLOGY OF THE MOGOLLON -DATIL VOLCANIC PROVINCE Progress Report on the Mogollon Plateau volcanic field, southwestern New Mexico, No. 3—Surface expression of a pluton Wolfgang E. Elston, Rodney C. Rhodes, Peter J. Coney, and Edmond G. Deal 3 Structure, volcanic stratigraphy, and gravity across the Mogollon Plateau, New Mexico Peter J. Coney 29 Volcanic geology of the Mogollon Range and adjacent areas, Catron and Grant Counties, New Mexico Rodney C. Rhodes 42 Volcano-tectonic structures in the San Mateo Mountains, Socorro County, New Mexico Edmond G. Deal and Rodney C Rhodes 51 Stratigraphy and structure of the northwestern part of the Mogollon Plateau'volcanic province, Catron County, New Mexico Rodney C. Rhodes and Eugene I. Smith 57 Tertiary extrusive sheets and related intrusions in the Black Range, New Mexico George E. Ericksen and Helmuth Wedow, Jr. 63 Volcanic geology of the northern Black Range, New Mexico Ronald V. Fodor 68 Structure and petrology of the John Kerr Peak dome complex, southwestern New Mexico Eugene I. Smith 71 Geology and flow directions of volcanic rocks of the North Star Mesa quadrangle, Grant County, New Mexico M J Aldrich, Jr. 79 LATE CENOZOIC BASALTS Major-element variations of late Cenozoic basalts of New Mexico Ken-Ichiro Aoki and Albert M. Kudo 82 The Potrillo basalt field, south-central New Mexico Jerry M. Hoffer 89 TOPICAL PAPERS Tectonic significance of mid-Tertiary volcanism in the Basin and Range province: A critical review with special reference to New Mexico Wolfgang E. Elston 93 Petrologic framework of the Mogollon Plateau volcanic ring complex, New Mexico—Surface expression of a major batholith Rodney C. Rhodes 103 Gravity survey of the Mogollon Plateau volcanic province, southwestern New Mexico Douglas H. Krohn 113 Fission-track ages of Tertiary volcanic and plutonic rocks, Mogollon Plateau, southwestern New Mexico Eugene I. Smith, M. J. Aldrich, Jr., Edmond G. Deal, and Rodney C. Rhodes 117 Paleomagnetic studies of volcanic rocks from the Mogollon Plateau area of Arizona and New Mexico D W Strangway, J. Simpson and D. York 119 Control of mineralization by mid-Tertiary volcanic centers, southwestern New Mexico Wolfgang E. Elston, Rodney C. Rhodes, and Edward E. Erb 125 [NEW MEXICO GEOLOGICAL SOCIETY GLOSSARY Glossary of stratigraphic terms of the Mogollon-Datil volcanic province, New Mexico Wolfgang E. Elston 131 REFERENCES CITED 145 CONTENTS OF SUPPLEMENTAL POCKET Figure 2. Reconnaissance geologic map of part of the Mogollon-Datil volcanic province, New Mexico Elston, Rhodes, Coney, and Deal Table 1. Stratigraphic correlation of mid-Tertiary volcanic rocks, Mogollon-Datil volcanic province, New Mexico Elston, Rhodes, Coney, and Deal Figure 9. Preliminary tectonic map of the Mogollon-Datil volcanic province, New Mexico Elston, Rhodes, Coney, and Deal Figure 1. Structure, volcanic stratigraphy, and gravity across the Mogollon Plateau, New Mexico Coney Figure 3. Reconnaissance geologic map of the Mogollon Range and adjacent areas, New Mexico Rhodes (a) Figure 2. Geologic map of the Tularosa Mountains and adjacent areas, New Mexico Rhodes and Smith Figure 2. Geologic map of the northern Black Range, New Mexico Fodor Figure 2. Geology and flow directions of volcanic rocks of the North Star Mesa quadrangle, Grant County, New Mexico Aldrich Figure 1. Bouguer gravity map of the Mogollon Plateau, southwestern New Mexico Krohn Figure 2. Residual gravity and geologic map of the Mogollon Plateau Krohn SPECIAL PUBLICATION NUMBER 51 FOREWORD This volume has been a long time in the making. The call for conceived, as the implications of plate tectonics and the Apollo papers went out in late 1970 and papers were received in 1971 program became apparent. It is hoped that this volume will fill and 1972. Plans called for publication as University of New some of the need for specific regional information. Mexico Publication in Geology No. 8. Tentative approval had This volume recounts some of the progress of the last few been obtained before the call for papers was issued but by the years but it also points to the gaps that remain. Information on time papers had been reviewed and edited, the great financial trace-element and isotopic composition of Cenozoic volcanic crunch of the 1970's had struck in academia. UNM Press has an rocks of southwestern New Mexico is scanty. Crustal structure is established reputation and market in the humanities and social virtually unknown. The timing of events remains uncertain and sciences but was uncertain about the physical sciences. In 1973 controversial. Above all, large areas remain unmapped and the plan for University of New Mexico Publication in Geology many conclusions and correlations rest on shaky ground. The No. 8 had to be abandoned. work is continuing and whatever we may say this year, next year Efforts to find an alternative publisher were successful in May we may know better. 1975, when the Executive Committee of the New Mexico I would like to thank all contributors for their patience. Geological Society voted to sponsor this volume. Rodney Apologies are due to those librarians and bibliographers who Rhodes' tragic death had occurred just two months before and it have tried in vain to track down premature references to was decided to dedicate the volume to his memory. The University of New Mexico Publication in Geology No. 8. The technicalities of preparing manuscripts for the printer became work of most of the contributors from the University of New less overwhelming when Stuart A. Northrop agreed to accept Mexico was supported by NASA grant NGL-32-004-011; addi- coeditorship. To save printing costs, all bibliographies were tional support came from NASA grant NGR-32-004-062 from combined into one at the end of the volume. the NASA Planetology Office and from grants from the Research In the meantime, science had not stood still. All authors were Allocations Committee, University of New Mexico. Without the given an opportunity to revise their manuscripts. In general, unfailing patience of the coeditor, Stuart A. Northrop, this work papers that describe particular areas had remained up to date. would never have seen the light of day. He is responsible for all Papers that interpreted the data required extensive revision. consistencies of style and format. I take responsibility for editor's Specifically, all papers of which I am author or coauthor were footnotes. written or completely rewritten during 1975 and early 1976. All Special thanks are due to my most inspiring co-workers and other papers are essentially as they were in 1973. One article that severest critics, the present and former graduate students of the had been cited in the literature as being "in press" was Department of Geology, University of New Mexico. Many of withdrawn by the authors: Seager, W. R., and Clemons, R. E., them are authors or coauthors of papers in this volume. I am "Volcanic chronology and structure of the Blue Creek basin particularly grateful to Theodore J. Bornhorst and Edward E. region between Clifton, Arizona and Cliff, New Mexico." Erb who spent many unpaid hours filling the void in our In the years between 1970 and 1976 the growth of interest in research group left by the untimely death of Rodney Rhodes. Cenozoic volcanism in western North America has been aston- Finally, sincere thanks are due to my wife, Lorraine, for her ishing. Volcanic rocks, once regarded as mere overburden by patience and understanding during the many evenings and prospectors, have turned out to be a key in the understanding of weekends in which this volume kept me away from the family plate motions, composition of the Earth's interior, the distribu- circle. tion of mineral deposits, and the evolution of planets. My views WOLFGANG E. ELSTON have certainly changed drastically since this volume was first [NEW MEXICO GEOLOGICAL SOCIETY vi RODNEY CHARLES RHODES SPECIAL PUBLICATION NUMBER 51 MEMORIAL TO RODNEY CHARLES RHODES 1943-1975 Rodney Charles Rhodes was born in Durban, Natal, South BIBLIOGRAPHY OF RODNEY C. RHODES Africa, on September 16, 1943, and died as the result of a tragic highway accident in Illinois on March 29, 1975. His fiancée, 1964, Selenology: Nucleon, Jour. Univ. Natal Sci. Soc., v. 6, p. 61-65. Mary Minor. died in the same accident. They were on their way 1966, (with Leith. M. J.) Lithostratigraphic zones in the Table Mountain from Albuquerque to the home of Miss Minor's parents in Series of Natal labs.]: Geol. Soc. South Africa Program 9th Ann. Congress, Durban, p. 25. Benton, Illinois, where they planned to be married in a few days. ---- Geology of an area to the north of Mapumulo, Natal [M.Sc. Rodney Rhodes is survived by his mother, Mrs. Winifred Speed thesis]: Durban, Univ. Natal, 151 p. of Durban. 1967, (and Leith. M. J.) Lithostratigraphic zones in the Table Mountain The accident cut short a brilliant scientific career. Rodney Series of Natal: Geol. Soc. South Africa Trans., v. 70, p. 15-28. Rhodes earned a first-class B.Sc. degree in geology at the 1968, Some aspects of the post-depositional history of the Red Sands in University of Natal in 1963, followed by a first-class Honours coastal Natal: South African Jour. Sci., v. 64, p. 145-149. B.Sc. degree in 1964, and an M.Sc. (cum laude) degree in 1966. - --- Summary of the geology of the Mogollon Range, southwestern After a brief period of employment in the mining industry in New Mexico: Arizona Geol. Soc. Guidebook III to southern Arizona, P. 260-261. South Africa, he came to the University of New Mexico as a - --- (with Elston, W. E.. and Coney, P. J.) A progress report on the Ph.D. candidate in 1966, with a research assistantship in Mogollon Plateau volcanic province, southwestern New Mexico: volcanology and astrogeology.