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High-Resolution Correlation of a Time-Bounded Unit of the Pisco Formation, Peru Daniel J

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High-Resolution Correlation of a Time-Bounded Unit of the Pisco Formation, Peru Daniel J Loma Linda University TheScholarsRepository@LLU: Digital Archive of Research, Scholarship & Creative Works Loma Linda University Electronic Theses, Dissertations & Projects 12-2015 High-Resolution Correlation of a Time-Bounded Unit of the Pisco Formation, Peru Daniel J. O'Hare Follow this and additional works at: http://scholarsrepository.llu.edu/etd Part of the Geology Commons, and the Sedimentology Commons Recommended Citation O'Hare, Daniel J., "High-Resolution Correlation of a Time-Bounded Unit of the Pisco Formation, Peru" (2015). Loma Linda University Electronic Theses, Dissertations & Projects. 333. http://scholarsrepository.llu.edu/etd/333 This Thesis is brought to you for free and open access by TheScholarsRepository@LLU: Digital Archive of Research, Scholarship & Creative Works. It has been accepted for inclusion in Loma Linda University Electronic Theses, Dissertations & Projects by an authorized administrator of TheScholarsRepository@LLU: Digital Archive of Research, Scholarship & Creative Works. For more information, please contact [email protected]. Loma Linda University School of Medicine in conjunction with the Faculty of Graduate Studies ________________________ High-Resolution Correlation of a Time-Bounded Unit of the Pisco Formation, Peru by Daniel J. O’Hare ________________________ A Thesis submitted in partial satisfaction of the requirements for the degree Master of Science in Geology __________________________ December 2015 ©2015 Daniel O’Hare All Rights Reserved Each person whose signature appears below certifies that this dissertation in his/her opinion is adequate, in scope and quality, as a thesis for the degree of Master of Science. , Chairperson Kevin Nick, Associate Professor of Geology Leonard Brand, Professor of Palentology Paul Buchheim, Professor of Geology Ronald Nalin, Adjunct Assistant Professor of Earth and Biological Sciences iii ACKNOWLEDGEMENTS The author is extremely grateful to several people and organizations for their support and contributions to the success of this project. The Department of Earth and Biological Sciences at Loma Linda University and the Geoscience Research Institute provided funds to support this research. Fellow graduate students Monte Fleming and Jankel Coronado and Orlando Poma, a researcher at the Universidad Peruana Unión, provided much assistance with the field work. The committee members Dr. Kevin Nick, Dr. Ronald Nalin, Dr. Leonard Brand, and Dr. Paul Buchheim provided much guidance and input. Dr. Nick was very patient, helpful, and available for consultation throughout the project, and each of the other committee members provided valuable feedback and guidance with the research and thesis. I am also greatly appreciative of the endless support and encouragement of my parents, brothers and sister, friends, and relatives during the completion of this project. iv CONTENTS Acknowledgements ............................................................................................................ iv Contents .............................................................................................................................. v Tables ............................................................................................................................... viii Figures................................................................................................................................ ix Abbreviations ................................................................................................................... xiii Abstract of the Thesis ...................................................................................................... xiv Chapter 1. Introduction ............................................................................................................ 1 Goals and Significance ......................................................................................... 1 Geologic Setting and Background........................................................................ 3 2. Methods and Study Area ....................................................................................... 10 Field Methods ..................................................................................................... 10 Laboratory Work ................................................................................................ 14 Synthesis Work .................................................................................................. 16 3. Results ................................................................................................................... 18 Map of Time Surface.......................................................................................... 18 Facies Descriptions ............................................................................................ 18 Facies Sc: Coarse Sandstone ............................................................................... 22 Facies Sldp: Planar-Laminated Diatomaceous Siltstone ................................. 24 Facies Sldm: Massive Diatomaceous Siltstone ................................................ 26 Facies Sld: Diatomaceous Siltstone with Climbing Wave Ripples ............... 27 Facies Sfsl: (Planar-Laminated) Fine Sand to Siltstone .................................. 29 Facies T: Tuff ........................................................................................................ 30 v Sections .............................................................................................................. 32 Measured 40Ar/39Ar Dates of Tuffs .................................................................... 48 Magnetic Susceptibility ...................................................................................... 56 4. Discussion .............................................................................................................. 58 Map..................................................................................................................... 58 Structure Implications .......................................................................................... 59 Paleoenvironmental Interpretation of Facies...................................................... 59 Interpretation of Facies Sc (Coarse Sandstone)................................................ 59 Interpretation of Facies Sldp ............................................................................... 61 Interpretation of Facies Sldm .............................................................................. 61 Interpretation of Facies Sld ................................................................................. 62 Interpretation of Facies Sfsl: Fine Sandy Siltstone .......................................... 62 Interpretation of Facies T .................................................................................... 63 Post-Depositional Processes ............................................................................... 63 Provenance ......................................................................................................... 64 Tuffs ....................................................................................................................... 64 Sandstones and Siltstones .................................................................................... 64 Diatoms .................................................................................................................. 66 Stratigraphic Sections and Correlation ............................................................... 66 Identification of Tuffs with Unique Characteristics and Dates ...................... 66 The Dark Gray Tuff and Correlation of the Top of the Section ..................... 67 The Dated White Tuff and Correlation of the Base of the Sections .............. 69 Are the Tuffs Airfall?........................................................................................... 71 Correlation of the Top vs. the Base .................................................................... 72 Correlating Units on Each Side of the Ica River .............................................. 75 40Ar/39Ar Dates of Tuffs ..................................................................................... 76 Magnetic Susceptibility ...................................................................................... 77 Paleoenvironmental Model ................................................................................ 80 Chemistry .............................................................................................................. 81 vi Temperature/Climate ........................................................................................... 82 Sedimentary Processes and Depositional Stages ............................................. 83 5. Conclusions ........................................................................................................... 94 References ......................................................................................................................... 96 Appendices Sample Descriptions and Data from Each Facies .................................................... 101 Grain Size Data from Laser Diffraction ................................................................... 139 vii TABLES Table Page 1. Facies and their Characteristics ...............................................................................20 2. 40Ar/39Ar radiometric age results .............................................................................49
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