The Geology of a Portion of the Quincy l5’ Quadrangle Plumas County, California By DOUGLAS INGRAM SHEEKS B.A., Geology (California State University, Sonoma) 1974 Thesis Submitted in partial satisfaction of the requirements for the degree of Master of Science in Geology in the OFFICE OF GRADUATE STUDIES of the UNIVERSITY OF CALIFORNIA DAVIS Approved: Eldridge M. Moores, Chairman Howard W. Day Peter Schiffman Committee in Charge 2016 i. © Copyright by Douglas Ingram Sheeks 2016 All Rights Reserved DEDICATION This thesis is dedicated to the late Professor Cordell Durrell and to all past, present, and future students of geology - Alvarez’s* “noble science” - whether amateur, professional, or academic, without whose dedication, work, and insight our understanding of this awe-inspiring planet and the rocks that we all live on would be impoverished to become myth, or worse. ACKNOWLEDGEMENTS My thanks go to a number of individuals. Chief among them is Professor Durrell, my thesis advisor at the University of California, Davis, and while I conducted the initial fieldwork for this thesis. Included in my appreciation are my dear wife, Gayle, who maintained the hope and the faith that this effort would finally bear fruit; my former, fellow students, including Professor Jad D’Allura, for his important contributions to northern Sierra Nevada geology and gracious permission to include a portion of his mapping in this report’s geologic map, and Joe DeVay for his work on the Shoo Fly rocks (and with the late Gerard Bond), encouragement, discussions, reviewing the draft manuscript, and for loaning me his Shoo Fly thin sections. I also thank Larry Garside (University of Nevada, Reno) *Alvarez, W., 2005, “The noble (but neglected) history of geology as a science: a tribute to Eldridge Moores.” Geological Society of America Abstracts with Programs, vol. 37, no. 4, page 55 (April). ii. for providing the initial spark for me to awaken this project from a long slumber; Professor Thomas A. Anderson (Sonoma State University) for his review of the draft manuscript; and the late Professor William R. Dickinson** (University of Arizona) for his patience and generosity in answering my questions about matrix (cited in this report) and in sending me this: “Happy to be of any service. Our business is a communal effort and anyone energetic enough to generate fresh point counts (few do these days!) has my ear and attention.” Sadly, I did not share my results with him before his passing. My thanks also go to the esteemed members of my thesis committee: Professors Eldridge M. Moores (Chair), Howard W. Day, and Peter Schiffman. I am forever grateful to them for their generosity, guidance, and the opportunity to put into effect the spirit of what Professor Moores expressed in his 1985 editorial in the journal “Geology;”*** to reinterpret and reevaluate my previous mapping in light of new understandings, hypotheses, and questions that had since arisen. The inclusion as appendices to this thesis of the Measurement Uncertainty tables for the major oxide and rare earth element constituents is with the express permission (2016) of SGS Minerals Services (SGS Canada, Inc.), Lakefield, Ontario, Canada. **Additional inspiration is available to all through the series of short video interviews with Professor Dickinson that may be viewed here: https://www.youtube.com/channel/UCoJlkm0iPZmptz0-tVROLDw ***Moores, E. M., 1985, “Editorial.” Geology, v. 13, n. 1, p. 3. January. iii. A typical view along the Middle Fork of the Feather River. The image is toward the northwest, upstream from the Quincy-La Porte Road bridge (Section 15, T23N, R10E). Here, both sides of the river are underlain by Ordovician-Silurian Shoo Fly Complex rocks that include metamorphosed sandstone, shale (slate), chert, and some pods of limestone. The outcrop in the foreground is grey slate that shows near-vertical cleavage striking northwest. iv. CONTENTS Dedication.................................................................................................................ii. Acknowledgments.....................................................................................................ii. List of Tables............................................................................................................xi. List of Figures..........................................................................................................xii. Abstract......................................................................................................................1. I. Introduction............................................................................................................4. I.A. Location.......................................................................................................4. I.B. Purpose and Objectives................................................................................4. I.C. Geographic Setting.......................................................................................6. I.D. Accessibility.................................................................................................8. II. Geologic Setting.....................................................................................................9. III. Previous Investigations in the Northern Sierra Nevada......................................13. IV. Descriptions of the Mapped Units......................................................................17. IV.A. Introduction..............................................................................................17. IV.B. Subjacent Rocks.......................................................................................21. IV.B.1. Shoo Fly Complex.............................................................................21. IV.B.1.a. Previous Studies........................................................................21. IV.B.1.b. Present Study............................................................................31. IV.B.1.c. Definition..................................................................................32. IV.B.1.d. Lithology...................................................................................36. v. CONTENTS (continued) IV.B.1.d.i. Sedimentary Rocks...................................................................38. IV.B.1.d.ii. Shoo Fly Sandstone Petrography.............................................41. IV.B.1.iii. Intrusive Rocks..........................................................................46. IV.B.1.e. Age and Correlation....................................................................47. IV.B.2. Structure of the Shoo Fly Rocks..........................................................50. IV.B.3. Sierra Buttes Formation.......................................................................53. IV.B.3.a. Definition.....................................................................................53. IV.B.3.b. Lithology.....................................................................................53. IV.B.3.c. Age...............................................................................................54. IV.B.4. Elwell Formation..................................................................................55. IV.B.4.a. Definition.....................................................................................55. IV.B.4.b. Lithology......................................................................................55. IV.B.4.c. Age...............................................................................................56. IV.B.5. Taylor Formation..................................................................................57. IV.B.5.a. Definition.....................................................................................57. IV.B.5.b. Lithology.....................................................................................57. IV.B.5.c. Age..............................................................................................58. IV.C. Superjacent Rocks......................................................................................59. IV.C.1. Introduction.........................................................................................59. vi. CONTENTS (continued) IV.C.2. Lovejoy basalt...................................................................................66. IV.C.2.a. Definition..................................................................................66. IV.C.2.b. Distribution...............................................................................66. IV.C.2.c. Lithology...................................................................................68. IV.C.2.d. Age and Correlation..................................................................70. IV.C.3. Ingalls formation...............................................................................72. IV.C.3.a. Definition..................................................................................72. IV.C.3.b. Distribution...............................................................................73. IV.C.3.c. Lithology...................................................................................73. IV.C.3.d. Age and Correlation..................................................................75. IV.C.4. Bonta gravels.....................................................................................75. IV.C.4.a. Definition...................................................................................75. IV.C.4.b.