The Metamorphic and Plutonic Rocks of the Southernmost Sierra Nevada, California, and Their Tectonic Framework U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1381 The Metamorphic and Plutonic Rocks of the Southernmost Sierra Nevada, California, and Their Tectonic Framework By DONALD C. ROSS U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1381 UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1989 DEPARTMENT OF THE INTERIOR MANUEL LUJAN, JR., Secretary U.S. GEOLOGICAL SURVEY Dallas L. Peck, Director Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government Library of Congress Cataloging-in-Publication Data Ross, Donald Clarence, 1924 The metamorphic and plutonic rocks of the southernmost Sierra Nevada, California, and their tectonic framework / by Donald C. Ross. p. cm. (U.S. Geological Survey professional paper ; 1381) Bibliography: p. Supt.ofDocs.no.: 119.16:1381 1. Rocks, Igneous Sierra Nevada Mountains (Calif, and Nev.) 2. Rocks, Metamorphic Sierra Nevada Mountains (Calif, and Nev.) I. Title. II. Series. QE461.R645 1989 552'.1'097944 dc20 89-6000136 CIP For sale by the Books and Open-File Reports Section U.S. Geological Survey, Federal Center, Box 25425, Denver, CO 80225 CONTENTS Abstract---------------------------- l Plutonic rocks- ------------------------ 23 Introduction- ------------------------- 1 Units north of the Garlock fault- ------------- 23 Acknowledgments----------------------- 3 Granitic rocks related(?) to the San Emigdio- Metamorphic rocks ---------------------- 3 Tehachapi terrane ---------------- 23 Metasedimentary rocks of the Keene area- -------- 3 Quartz diorite to tonalite of Antimony Peak- - - - 23 Setting ------------------------ 3 Diorite to tonalite of Tehachapi Mountains - - - - 24 Rock types and petrography- ------------- 5 Tonalite of Bear Valley Springs ------------ 26 Metasedimentary rocks of Salt Creek ----------- 6 Setting ---------------------- 26 Setting -------------------------- 6 Petrography-------------------- 26 Rock types and petrography- ------------- 6 Relation to the gneiss, amphibolite, and granulite Gneiss, amphibolite, and granulite of San Emigdio- of San Emigdio-Tehachapi Mountains - - - - 32 Tehachapi Mountains -------------- 7 Felsic masses within the tonalite of Bear Valley Setting ------------------------ 7 Springs ------------------- 33 Description of rock types --------------- 7 Tonalite of Mount Adelaide -------------- 36 Gneiss ----------------------- 7 Setting ---------------------- 36 Amphibolite -------------------- 8 Petrography- ------------------- 37 Granofels --------------------- 9 Tonalite of Hoffman Canyon ------------- 39 Granulite --------------------- 9 Setting ---------------------- 39 Impure quartzite and calc-hornfels -------- 9 Petrography- ------------------- 40 Mafic metamorphic and plutonic bodies related(?) to the Granite of Saddle Spring Road ------------ 42 San Emigdio-Tehachapi terrane --------- 10 Granodiorite of Lebec ----------------- 42 Live Oak ----------------------- 10 Setting ---------------------- 42 Breckenridge --------------------- H Petrography -------------------- 43 Pampa------------------------- H Fine-grained facies ---------------- 45 Walker ------------------------ H Felsic marginal facies --------------- 45 Caliente ------------------------ 12 Granodiorite of Claraville --------------- 45 Comanche ----------------------- 12 Setting ---------------------- 45 Cummings----------------------- 12 Petrography-------------------- 48 Loop inclusion swarm ----------------- 13 Granodiorite of Sorrell Peak ------------- 51 Tweedy ------------------------ 13 Setting ---------____________________ 51 Cameron ----------------------- 13 Petrography- ------ Cinco ------------------------- 14 Granite of Tehachapi Airport __________ 52 Jawbone------------------------ 14 Setting --------- ---------- 52 Eagle Rest Peak ------------------- 15 Petrography- ------ ---------- 52 Felsic gneiss bodies related(?) to the San Emigdio- Granite of Lone Tree Canyon ---------- 55 Tehachapi terrane ---------------- 15 Setting --------- ---------- 55 Mountain Park -------------------- 16 Petrography - ---------- 55 Tweedy Creek- -------------------- 16 Granite of Brush Mountain -------------- 56 Brown Meadow -------------------- 16 Setting ---------------------- 56 Metavolcanic rocks of French Gulch- ----------- 16 Petrography- ------------------- 56 Setting ------------------------ 16 Granite of Bishop Ranch --------------- 57 Rock types and petrography- ------------- 17 Setting ---------------------- 57 Metamorphic rocks in the subsurface of the southeastern Petrography-------------------- 58 San Joaquin Valley --------------- 17 Plutonic rocks in the subsurface of the southeastern San Metaigneous rocks- ------------------ 17 Joaquin Valley- ----------------- 58 Metasedimentary rocks ---------------- 17 Diorite and gabbro ------------------ 58 Relation to the Pampa Schist ------------- 18 Hornblende-biotite tonalite -------------- 59 Bean Canyon Formation ------------------ 18 Biotite tonalite -------------------- 60 Setting ------------------------ 18 Granitic rocks, undivided --------------- 60 Rock types and petrography- ------------- 18 Units south of the Garlock fault- ------------- 61 Age -------------------------- 20 Granodiorite of Gato-Montes -------------- 61 Pampa Schist of Dibblee and Chesterman (1953) ----- 20 Setting ---------------------- 61 Setting ------------------------ 20 Petrography- ------------------- 61 Rock types and petrography- ------------- 21 Granodiorite of Cameron --------------- 61 Rand Schist ------------__---_----__ 21 Setting ---------------------- 61 Setting and age -------------------- 21 Petrography-------------------- 61 Rock types and petrography- ------------- 21 Granite of Tejon Lookout --------------- 62 Rand(?) Schist in the San Emigdio Mountains ----- 23 Setting ---------------------- 62 in IV CONTENTS Plutonic rocks Continued Pa& Tectonic framework Continued Pase Units south of the Garlock fault Continued Seismicity ------------------------- 94 Granite of Tejon Lookout Continued Structural implications of the Sierra Nevada tail ----- 99 Petrography-------------------- 65 Structural elements of the southernmost Sierra Granite of Bean Canyon- --------------- 65 Nevada--------------------- 101 Mafic igneous rocks in (and associated with) the Bean Element 1- ---------------------- 101 Canyon Formation- --------------- 65 Subelement 1A ------------------ 101 Miscellaneous topics (metamorphic and plutonic rocks) - - - - 67 Subelement IB ------------------ 102 Distribution of selected minerals and their significance - - 67 Element 2----------------------- 103 Hypersthene---------------------- 67 Subelement 2A ------------------ 104 Coarse-haloed red garnet --------------- 69 Subelement 2B ------------------ 104 Brown hornblende- ------------------ 73 Element 3----------------------- 104 Reddish-brown biotite ----------------- 75 Element 4----------------------- 104 Muscovite ----------------------- 75 Element 5----------------------- 104 Sillimanite and andalusite --------------- 77 Crustal level of the basement rocks of the Sierra Prehnite------------------------ 79 Nevada--------------------- 105 Epidote and allanite ------------------ 80 Aplite-alaskite-pegmatite dikes as crustal-depth Tourmaline ---------------------- 80 indicators -------------------- 106 Polka-dot dikes ---------------------- 81 Thoughts on batholithic roots --------------- 107 Possible correlation of the granodiorites of Lebec and Comparison of the hypersthene-bearing and related rocks Gato-Montes------------------- 82 of the southernmost Sierra Nevada with similar Selected modal-mineral plots --------------- 83 rocks in the Santa Lucia Range --------- 108 Radiometric-age data on the plutonic rocks -------- 83 Chemical data- ------------------------ 110 Metamorphic grade of the hornblende-rich terranes - - - - 86 Chemical characteristics of the plutonic rocks- ------ 110 Tectonic framework- --------------------- 88 Rare-earth elements- ------------------- 112 Faults that offset the basement significantly ------- 88 Heat production and heat-producing elements- ------ 113 Garlock fault displacement -----.----------- 89 Metallic mineralization -------------------- 113 Pastoria thrust controversy ---------------- 91 References cited- ----------------------- 114 Cataclastic rocks --------------------- 93 ILLUSTRATIONS [Plates are in pocket] PLATE 1. Reconnaissance geologic map of basement rocks of the southernmost Sierra Nevada, California 2. Map showing locations of chemically and modally analyzed granitic-rock samples FIGURES 1-4. Maps showing: Page 1. Location and setting of the study area in the southernmost Sierra Nevada, California ------------ 2 2. Selected physical and cultural features in the southernmost Sierra Nevada ------------------ 4 3. Locations of samples for which oxygen-isotopic data have been determined ------------------ 8 4. Locations of hornblende-rich metamorphic and magmatic terranes ---------------------- 10 5-8. Triangular diagrams showing modal plots of: 5. Quartz diorite to tonalite of Antimony Peak- --------------------------------- 24 6. Averages of plutonic-rock units ---------------------------------------- 25 7. Diorite to tonalite of the Tehachapi Mountains -------------------------------- 27 8. Tonalite of Bear Valley Springs ---------------------------------------- 29 9. Map showing locations of samples of diorite to tonalite