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UCLA UCLA Electronic Theses and Dissertations Title Oligocene-Miocene Sedimentary and Volcanic Strata of the Vincent Gap Region, Eastern San Gabriel Mountains, Southern California, USA, and Their Tectonic Significance Permalink https://escholarship.org/uc/item/5d86229k Author Coffey, Kevin Thomas Publication Date 2015 Supplemental Material https://escholarship.org/uc/item/5d86229k#supplemental Peer reviewed|Thesis/dissertation eScholarship.org Powered by the California Digital Library University of California UNIVERSITY OF CALIFORNIA Los Angeles Oligocene-Miocene Sedimentary and Volcanic Strata of the Vincent Gap Region, Eastern San Gabriel Mountains, Southern California, USA, and Their Tectonic Significance A thesis submitted in partial satisfaction of the requirements for the degree Master of Science in Geology by Kevin Thomas Coffey 2015 © Copyright by Kevin Thomas Coffey 2015 ABSTRACT OF THE THESIS Oligocene-Miocene Sedimentary and Volcanic Strata of the Vincent Gap Region, Eastern San Gabriel Mountains, Southern California, USA, and Their Tectonic Significance by Kevin Thomas Coffey Master of Science in Geology University of California, Los Angeles, 2015 Professor Raymond V. Ingersoll, Chair The Vincent Gap region of the eastern San Gabriel Mountains in southern California is a small but important piece of an originally continuous terrane separated into the Tejon, Soledad and Orocopia regions by the San Andreas fault system. The middle-upper Miocene Punchbowl Formation has been considered the oldest Neogene strata of the Vincent Gap region. The present study documents that strata southeast of the main exposure of the Punchbowl Formation, though aerially restricted, are temporally extensive; together with the Punchbowl Formation, they comprise a sedimentary record that spans from ~25 to ~6 Ma, includes equivalents of the Vasquez, Tick Canyon and Mint Canyon formations of the Soledad region, and relates to three sequential tectonic stages in southern California. Uppermost Oligocene-lower Miocene strata are closely correlative with the Plush Ranch, Vasquez and Diligencia formations of the Tejon, ii Soledad and Orocopia regions, respectively; they formed during extension induced by triple- junction instability. Interbedded 25 Ma volcanics near the base of these strata are chemically and chronologically similar to those of the Plush Ranch, Vasquez and Diligencia formations. Middle Miocene strata beneath the Punchbowl Formation are equivalent to the Tick Canyon Formation of the Soledad region, and document exhumation of the Pelona Schist. Sandstone petrofacies, conglomerate composition and detrital-zircon age data provide compatible but distinct provenance information; using all three in combination results in a more complete understanding of the provenance of each of these units. The results of this study imply that transrotation of the western Transverse Ranges and accompanying basement exhumation extended farther inboard than generally thought, adjacent to if not across the future trace of the San Andreas fault. Data from the Vincent Gap also reveal that the middle-upper Miocene Punchbowl Formation was likely part of a large drainage system, with the Mint Canyon Formation of the Soledad region representing a tributary of this system that joined downstream, and the Caliente Formation of the Tejon region representing the confluence of the two. iii The thesis of Kevin Thomas Coffey is approved. Raymond V. Ingersoll Axel K. Schmitt An Yin University of California, Los Angeles 2015 iv TABLE OF CONTENTS: Page: ABSTRACT ii APPROVAL PAGE iv LIST OF FIGURES x LIST OF PLATES xi LIST OF TABLES xi LIST OF APPENDICES xi ACKNOWLEDGMENTS xii INTRODUCTION 1 Purpose 1 Location 1 REGIONAL GEOLOGY 2 Plate Interactions 2 Convergent Tectonics and Initiation of the Transform Margin 2 Unstable Configuration of the Mendocino Triple Junction 3 Formation of Slab Window 3 Microplate-Capture Event 1: Monterey and Arguello Plates 4 Microplate-Capture Event 2: Guadalupe and Magdalena Plates 5 Microplate-Capture Event 3: Baja California 6 Tectonic Stages 6 Triple-Junction-Migration-Induced Extension and Volcanism (24-18 Ma) 6 Transrotation (18-12 Ma) 6 v Paleomagnetic data 7 Geologic data 8 Seismic data 9 Exhumation of the Pelona-Orocopia-Rand-Catalina schists 9 San Gabriel transform (12-6 Ma) 11 Transpression (6 or 5 Ma-present) 12 Palinspastic Reconstructions 13 Pre-Oligocene Offset Equivalents and Their Zircon Ages 14 Paleoproterozoic Gneiss 14 Mesoproterozoic Anorthosite-Gabbro-Syenite-Norite Complex 14 Late Triassic Lowe Granodiorite 15 Jurassic and Cretaceous Granitoids 16 Pelona-Orocopia-Rand-Catalina Schists 17 Uppermost Cretaceous-Eocene San Francisquito and Maniobra Formations and Unnamed Strata 18 Late Oligocene Telegraph Peak Granite and Associated Sills and Dikes 20 Oligocene-Miocene Sedimentary Strata 20 Uppermost Oligocene-Lower Miocene: Plush Ranch/Vasquez/Diligencia Formations 20 Plush Ranch Formation 20 Vasquez Formation 22 Diligencia Formation 24 Relationships of Oligocene-Miocene formations 26 Middle Miocene: Tick Canyon/Paradise Springs Formations 27 vi Tick Canyon Formation 27 Paradise Springs formation 29 Unnamed shale of Peanut Hill 29 Middle-Upper Miocene: Caliente/Mint Canyon/Punchbowl Formations 30 Caliente Formation 30 Mint Canyon Formation 30 Relationship of Caliente and Mint Canyon formations 31 Punchbowl Formation 31 Upper Miocene Castaic Formation 33 METHODS 34 Geologic Mapping 34 Paleocurrent Data 34 Conglomerate Composition 35 Sandstone Composition 35 Collection and Preparation 35 Petrography 36 Detrital-Zircon Analysis (LA MC-ICPMS) 36 Collection and Preparation 36 Analysis 38 Igneous-Zircon Analysis (SIMS) 39 Collection and Preparation 39 Analysis 40 Volcanic Trace-Element Analysis (XRF and ICPMS) 41 vii X-Ray Fluorescence (XRF) 41 Sample preparation 41 Analysis 42 ICPMS 42 Sample preparation 42 Analysis 43 RESULTS 44 Geologic Mapping 44 Paleocurrent Data 45 Conglomerate Composition 45 Sandstone Composition 46 Igneous-Zircon Analysis (SIMS) 47 Detrital-Zircon Analysis (LA MC-ICPMS) 47 Volcanic Trace-Element Analysis (XRF and ICPMS) 48 DISCUSSION 49 Late Jurassic Granitoid 49 Hypabyssal Intrusive 50 Detrital-Zircon Age Data 51 Ancestral Blue Ridge Drainage Divide 52 Uppermost Oligocene to Lower Miocene Vasquez Formation 52 Sedimentary Strata 52 Volcanic Strata 54 Middle Miocene Paradise Springs Formation and Unroofing Sequence 57 viii Unroofing Sequence in the Charlie Canyon Subbasin of the Soledad Region 59 Fenner Fault as the Major Detachment Fault 59 Middle to Upper Miocene Punchbowl Formation and Drainage Integration 61 Post-Miocene Deformation 64 CONCLUSIONS 66 FIGURES 69 TABLES 94 APPENDICES 98 REFERENCES CITED 151 ix LIST OF FIGURES Page: Figure 1: Regional map 69 Figure 2. Schematic block diagrams illustrating capture of Monterey microplate by Pacific plate 70 Figure 3. Interaction of the Pacific, North American and Farallon plates from 24 Ma to present 72 Figure 4: Cross sections through inner borderland 74 Figure 5: Transrotational domains of the western Transverse Ranges 75 Figure 6: Geologic map of part of Charlie Canyon subbasin of Soledad region 76 Figure 7: Sandstone composition of Oligocene-Miocene Vincent Gap strata 78 Figure 8: Comparison of sandstone composition of Paradise Springs and Tick Canyon formations 79 Figure 9: Comparison of sandstone composition of Punchbowl, Caliente and Mint Canyon formations 80 Figure 10: Igneous- and detrital-zircon ages of all Vincent Gap samples 81 Figure 11: Classification of volcanic samples 83 Figure 12: Plots of (A) Th, (B) U and (C) Hf vs. Ta for volcanic samples 84 Figure 13: Chondrite-normalized rare-earth-element abundances of volcanic samples 85 Figure 14: Schematic paleogeography, source rocks and depositional systems of Tejon-Soledad-Vincent Gap-Orocopia regions 86 Figure 15: Schematic composite stratigraphic sections of the Vincent Gap region and offset equivalents 89 Figure 16: Comparison of detrital-zircon ages of Punchbowl, Caliente and Mint Canyon formations 92 x LIST OF PLATES Page: (Plates can be found in the back of printed versions and as online supplements) Plate 1: Geologic map of the Vincent Gap region, eastern San Gabriel Mountains, southern California, USA - Plate 2: Simplified geologic map of the Vincent Gap region, showing sample locations and conglomerate-composition and paleocurrent data - Plate 3: Cross sections of geologic map of Plate 1 - LIST OF TABLES Table 1: Definition of conglomerate-clast categories 94 Table 2: Definition of original and recalculated sandstone point-count grain categories 95 Table 3: Recalculated sandstone point-count data 96 Table 4: Recalculated sandstone point-count data of Raymond V. Ingersoll (unpublished) 97 LIST OF APPENDICES Appendix A: Latitude and longitude of sample and measurement locations 98 Appendix B: Detrital-zircon data 101 Appendix C: Igneous-zircon data 132 Appendix D: Raw and corrected paleocurrent data 137 Appendix E: Raw conglomerate-count data 141 Appendix F: Raw sandstone point-count data 142 Appendix G: XRF major- and trace-element data 144 Appendix H: ICPMS trace-element data 145 Appendix I: Field photographs 146 xi ACKNOWLEDGMENTS I thank my advisor, Raymond V. Ingersoll, for guiding me through this research and providing crucial instruction, insight and feedback on countless occasions. I thank my other committee members, Axel K. Schmitt and An Yin, for their helpful comments. I thank Axel K. Schmitt for assistance in preparing and analyzing igneous-zircon samples and interpreting

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