Notice Concerning Copyright Restrictions
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Temporal and Spatial Trends of Late Cretaceous-Early Tertiary Underplating of Pelona and Related Schist Beneath Southern California and Southwestern Arizona
spe374-14 page 1 of 26 Geological Society of America Special Paper 374 2003 Temporal and spatial trends of Late Cretaceous-early Tertiary underplating of Pelona and related schist beneath southern California and southwestern Arizona M. Grove Department of Earth and Space Sciences, University of California, 595 Charles Young Drive E, Los Angeles, California 90095-1567, USA Carl E. Jacobson Department of Geological and Atmospheric Sciences, Iowa State University, Ames, Iowa 50011-3212, USA Andrew P. Barth Department of Geology, Indiana University–Purdue University, Indianapolis, Indiana 46202-5132, USA Ana Vucic Department of Geological and Atmospheric Sciences, Iowa State University, Ames, Iowa 50011-3212, USA ABSTRACT The Pelona, Orocopia, and Rand Schists and the schists of Portal Ridge and Sierra de Salinas constitute a high–pressure-temperature terrane that was accreted beneath North American basement in Late Cretaceous–earliest Tertiary time. The schists crop out in a belt extending from the southern Coast Ranges through the Mojave Desert, central Transverse Ranges, southeastern California, and southwest- ern Arizona. Ion microprobe U-Pb results from 850 detrital zircons from 40 meta- graywackes demonstrates a Late Cretaceous to earliest Tertiary depositional age for the sedimentary part of the schist’s protolith. About 40% of the 206Pb/238U spot ages are Late Cretaceous. The youngest detrital zircon ages and post-metamorphic mica 40Ar/39Ar cooling ages bracket when the schist’s graywacke protolith was eroded from its source region, deposited, underthrust, accreted, and metamorphosed. This interval averages 13 ± 10 m.y. but locally is too short (<~3 m.y.) to be resolved with our methods. -
Insights from Lowtemperature Thermochronometry Into
TECTONICS, VOL. 32, 1602–1622, doi:10.1002/2013TC003377, 2013 Insights from low-temperature thermochronometry into transpressional deformation and crustal exhumation along the San Andreas fault in the western Transverse Ranges, California Nathan A. Niemi,1 Jamie T. Buscher,2 James A. Spotila,3 Martha A. House,4 and Shari A. Kelley 5 Received 21 May 2013; revised 21 October 2013; accepted 28 October 2013; published 20 December 2013. [1] The San Emigdio Mountains are an example of an archetypical, transpressional structural system, bounded to the south by the San Andreas strike-slip fault, and to the north by the active Wheeler Ridge thrust. Apatite (U-Th)/He and apatite and zircon fission track ages were obtained along transects across the range and from wells in and to the north of the range. Apatite (U-Th)/He ages are 4–6 Ma adjacent to the San Andreas fault, and both (U-Th)/He and fission track ages grow older with distance to the north from the San Andreas. The young ages north of the San Andreas fault contrast with early Miocene (U-Th)/He ages from Mount Pinos on the south side of the fault. Restoration of sample paleodepths in the San Emigdio Mountains using a regional unconformity at the base of the Eocene Tejon Formation indicates that the San Emigdio Mountains represent a crustal fragment that has been exhumed more than 5 km along the San Andreas fault since late Miocene time. Marked differences in the timing and rate of exhumation between the northern and southern sides of the San Andreas fault are difficult to reconcile with existing structural models of the western Transverse Ranges as a thin-skinned thrust system. -
The Metamorphic and Plutonic Rocks of the Southernmost Sierra Nevada, California, and Their Tectonic Framework
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 -
Generalized Geologic Map of the Basement Rocks of the Southern Sierra Nevada, California
DEPARTMENT OF THE INTERIOR U.S. GEOLOGICAL SURVEY Generalized geologic map of the basement rocks of the southern Sierra Nevada, California by Donald C. Ross U.S. Geological Survey Open-File Report 8?-2?6 This report is preliminary and ha$ not been reviewed for conformity with U.S. Geological Survey editorial standards and stratigraphic nomenclature. Menlo Park, California 198? CONTENTS INTRODUCTION, DESCRIPTION OF MAP UNITS........................................2 SUMMARY OF BASEMENT GEOLOGIC FEATURES..........................21 REFERENCES CITED...............................................25 ILLUSTRATIONS Plates 1. Geologic map 2. Coverage of the area Figure 1. Intrusive relations for some granitic rocks 2o Generalized geologic map of the basement rocks of the southern Sierra Nevada, California ' INTRODUCTION The basement geology of the southern Sierra Nevada north to lat. 36°00f N. (plate 1) has generally been shown on previous compilations as basement rock undivided or as granitic rock containing some metamorphic bodies. Other maps have shown much more detail, but only for limited areas of the southern Sierra r\ Nevada. This map, which encompasses some A900 knr of basement exposures, is an attempt to present a somewhat standardized coverage of the basement rocks of this large area and, at the same time, to point out some of its petrograph- ic complexity, and to a lesser extent, to show some of the variety in the metamorphic pendant rocks. Certainly more complexity in the geology is pre sent than is grossly summarized here at a scale of 1:250,000. Coverage of the area has been somewhat uneven as shown on Plate 2 that indicates all localities where samples or other data have been collected. -
Southern California National Forests Land Management Plan Amendment
USDA FOREST SERVICE Southern California National Forests Land Management Plan Amendment Inventoried Roadless Area Analysis for the Angeles, Cleveland, Los Padres and San Bernardino National Forests of Southern California April 2012 The Southern California National Forests Inventoried Roadless Area (IRA) Analysis (FSH 1909.12-2007-1, Chapter 72) for a Land Management Plan Amendment. The proposed Amendment is a result of the January 3, 2011 Settlement Agreeement. Southern California Land Management Plan Amendment – IRA Analysis April, 2012 Table of Contents Angeles National Forest ..............................................................................................................9 Fish Canyon Inventoried Roadless Area ..................................................................................9 Overview .............................................................................................................................9 Capability .......................................................................................................................... 10 Availability ........................................................................................................................ 13 Need .................................................................................................................................. 14 Angeles National Forest ............................................................................................................ 16 Red Mountain Inventoried Roadless Area ............................................................................. -
Insights from the San Emigdio Schist, Southern California
J. metamorphic Geol., 2011 doi:10.1111/j.1525-1314.2011.00932.x Metamorphic evolution, partial melting and rapid exhumation above an ancient flat slab: insights from the San Emigdio Schist, southern California A. D. CHAPMAN,1 P. I. LUFFI,2 J. B. SALEEBY1 AND S. PETERSEN3 1Division of Geological and Planetary Sciences, California Institute of Technology, M ⁄ C 100-23 1200 E. California Blvd., Pasadena, CA 91125, USA ([email protected]) 2Department of Earth Science, Rice University MS-126, 6100 Main St., Houston, TX 77005, USA 3Department of Earth and Planetary Sciences, Harvard University, 20 Oxford St., Cambridge, MA 02138, USA ABSTRACT The San Emigdio and related Pelona, Orocopia, Rand and Sierra de Salinas schists of southern California were underplated beneath the southern Sierra Nevada batholith and adjacent southern California batholith along a shallow segment of the subducting Farallon plate in Late Cretaceous to early Tertiary time. These subduction accretion assemblages represent a regional, deeply exhumed, shallowly dipping domain from an ancient slab segmentation system and record the complete life cycle of the segmentation process from initial flattening and compression to final extensional collapse. An important unresolved question regarding shallow subduction zones concerns how the thermal structure evolves during the slab flattening process. New field relationships, thermobarometry, thermodynamic modelling and garnet diffusion modelling are presented that speak to this issue and elucidate the tectonics of underplating and exhumation of the San Emigdio Schist. We document an upsection increase in peak temperature (i.e. inverted metamorphism), from 590 to 700 °C, peak pressures ranging from 8.5 to 11.1 kbar, limited partial melting, microstructural evidence for large seismic events, rapid cooling (825–380 °C Myr)1) from peak conditions and an Ôout and backÕ P–T path. -
Late Cretaceous Gravitational Collapse of the Southern Sierra Nevada Batholith, California
Origin and Evolution of the Sierra Nevada and Walker Lane themed issue Late Cretaceous gravitational collapse of the southern Sierra Nevada batholith, California Alan D. Chapman1,2,*, Jason B. Saleeby1, David J. Wood1,†, Alison Piasecki1, Steven Kidder1, Mihai N. Ducea2, and Kenneth A. Farley1 1Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, USA 2Department of Geosciences, University of Arizona, Tucson, Arizona 85721, USA ABSTRACT between the shallow and deep crust during age. Furthermore, this effort focuses on specifi c extension, and (2) that the development of and elusive issues pertaining to Late Cretaceous The Sierra Nevada batholith is an modern landscape in southern California disruption and dispersion of the southern Sierra ~600-km-long, NNW-trending composite was greatly preconditioned by Late Creta- Nevada batholith and vicinity, including: (1) the arc assemblage consisting of a myriad of ceous tectonics. magnitude and timing of tectonic transport of plutons exhibiting a distinct transverse zona- upper crustal fragments along a regional detach- tion in structural, petrologic, geochrono- INTRODUCTION ment system; (2) the degree of strain coupling logic, and isotopic patterns. This zonation between differentially exhuming levels of the is most clearly expressed by a west-to-east In zones of convergence, regional gradients crust; (3) the importance of strike-slip faulting variation from mafi c to felsic plutonic assem- in gravitational potential energy can be relaxed during collapse; and (4) the extent to which blages. South of 35.5°N, the depth of expo- through lateral spreading and vertical thinning the development of the southern Sierra Nevada sure increases markedly, and fragments of of orogenic crust (e.g., Dewey, 1988; Rey et al., landscape was infl uenced by Late Cretaceous shallow-level eastern Sierra Nevada batho- 2001). -
Late Cretaceous Tectonic History of the Sierra-Salinia-Mojave Arc As
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 109, B02204, doi:10.1029/2003JB002845, 2004 Late Cretaceous tectonic history of the Sierra-Salinia-Mojave arc as recorded in conglomerates of the Upper Cretaceous and Paleocene Gualala Formation, northern California Ronald C. Schott1 and Clark M. Johnson Department of Geology and Geophysics, University of Wisconsin-Madison, Madison, Wisconsin, USA James R. O’Neil Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan, USA Received 14 October 2003; revised 5 November 2003; accepted 17 November 2003; published 11 February 2004. [1] Upper Cretaceous and Paleogene conglomerates in the Gualala basin of northern California likely preserve the westernmost record of sedimentation in California during the interval between cessation of Sierran batholith magmatism and inception of Neogene transform activity on the San Andreas fault system. Detailed chemical and H, O, Sr, Nd, and Pb isotope analyses of conglomerate clasts, as well as U/Pb zircon ages, identify two source types: (1) evolved granite, like those found in the Salinian block or eastern Sierra Nevada batholith, and (2) primitive oceanic arcs that were restricted to the western portions of the Mesozoic arc system. The provenance of the Gualala clasts can be entirely explained through derivation from the Sierra-Salinian-Mojave portion of the Mesozoic Cordilleran arc, and do not support models for extensive large-scale translation of the basin from low latitudes along a pre-Neogene transform fault system. Contemporaneous deposition of the contrasting lithologies in the Gualala basin is interpreted to reflect tectonic juxtaposition of the source terranes approximately 80 m.y. ago. Tectonic processes responsible for juxtaposition of the two source regions in the Late Cretaceous most probably involved zones of lithospheric weakness that later localized the San Andreas fault system in the Neogene. -
OFR-03-153 Pamphlet PDF File
Geologic Map of the Cuddy Valley quadrangle, Kern and Ventura Counties, California By Karl S. Kellogg Pamphlet to accompany Open-File Report 03-153 2003 This report is prelininary and has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the North American Stratigraphic Code. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. U.S. Department of the Interior U.S. Geological Survey Geologic Map of the Cuddy Valley Quadrangle, Kern and Ventura Counties, California By Karl S. Kellogg The Director of the USGS has approved this database, identified as USGS Open-File Report OF 03-153, for release and publication. Although this database has been subjected to review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, it is released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use. Digital files of this publication are located at the internet site: http://pub.usgs.gov/, including ARC/INFO export files which may be generated from a tar file (OFR 03-153.tar.Z). In addition, a PDF file of the map (OFR 03-153) may be downloaded, from which paper copies may be printed. A Section 508-compliant version of the map, OFR 03-153_508.pdf, may also be downloaded from the above internet site. The database manager is: Karl S. Kellogg (303) 236-1305 [email protected] U.S. -
APPENDICES A. Grazing and Haying NWRS Legal and Policy Considerations B. Bitter Creek National Wildlife Refuge Plant Taxa. C. D
APPENDICES A. Grazing and Haying NWRS Legal and Policy Considerations B. Bitter Creek National Wildlife Refuge plant taxa. C. DeVries 2009 Plant Survey Report. D. Record of San Joaquin Kit Fox sightings at Bitter Creek National Wildlife Refuge. E. Bitter Creek National Wildlife Refuge residual dry matter (RDM) monitoring data. F. Glossary of Terms G. Final Report Review Comments Appendix A. Grazing and Haying NWRS Legal and Policy Considerations Background Livestock grazing and haying occur on a number of units of the National Wildlife Refuge System (NWRS). Data for fiscal years 1999-2006 reveal that, on average, grazing occurred on 105 refuges annually (range = 67-114 refuges/yr) and totaled over 1.1 million acres per year (range = 911,460-1,388,531 ac/yr). On average, haying and/or mowing occurred on 211 refuges annually (range = 200-229 refuges/yr) and totaled over 85 thousand acres (range = 67, 552- 105,501 ac/yr).1 In selected circumstances and when properly managed, livestock grazing and haying can be valuable and cost-effective tools to help a refuge achieve its wildlife and habitat goals and objectives. Examples include short-term, high-intensity grazing at a particular time of year to help control invasive plants and thereby give native species a more competitive advantage; or using grazing or haying to remove tall or decadent grasses and provide short, vigorous grass fields for use by migrating or wintering geese and sandhill cranes. These management practices help refuges to achieve refuge purpose(s), goals, and objectives; and provide permittees with a financial return (in the form of forage).