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Role of extrusion of the Rand and Sierra de Salinas schists in Late Cretaceous extension and rotation of the southern Sierra Nevada and vicinity

Chapman, Alan D. and Kidder, Steven and Saleeby, Jason B. and Ducea, Mihai N. (2010) Role of extrusion of the Rand and Sierra de Salinas schists in Late Cretaceous extension and rotation of the southern Sierra Nevada and vicinity. Tectonics, 29 . Art. No. TC5006. ISSN 0278-7407. http://resolver.caltech.edu/CaltechAUTHORS:20101012-112134099

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Abstract

The Rand and Sierra de Salinas schists of southern California were underplated beneath the southern Sierra Nevada batholith and adjacent Mojave-Salinia region along a shallow segment of the subducting Farallon plate in Late Cretaceous time. Various mechanisms, including return flow, isostatically driven uplift, upper plate normal faulting, erosion, or some combination thereof, have been proposed for the exhumation of the schist. We supplement existing kinematic data with new vorticity and strain analysis to characterize deformation in the Rand and Sierra de Salinas schists. These data indicate that the schist was transported to the SSW from deep to shallow crustal levels along a mylonitic contact (the Rand fault and Salinas shear zone) with upper plate assemblages. Crystallographic preferred orientation patterns in deformed quartzites reveal a decreasing simple shear component with increasing structural depth, suggesting a pure shear dominated westward flow within the subduction channel and localized simple shear along the upper channel boundary. The resulting flow type within the channel is that of general shear extrusion. Integration of these observations with published geochronologic, thermochronometric, thermobarometric, and paleomagnetic studies reveals a temporal relationship between schist unroofing and upper crustal extension and rotation. We present a model whereby trench-directed channelized extrusion of the underplated schist triggered gravitational collapse and clockwise rotation of the upper plate.


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http://dx.doi.org/10.1029/2009TC002597 DOIArticle
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Additional Information:© 2010 American Geophysical Union. Received 24 August 2009; revised 16 March 2010; accepted 4 June 2010; published 15 September 2010. This research was supported by National Science Foundation grant EAR‐0739071. This is Caltech Tectonics Observatory Contribution 129. We thank Marty Grove, Peter Luffi, and Elisabeth Nadin for discussions. The manuscript benefited from thoughtful reviews by Carl Jacobson and Robert Miller. We thank Ralf Hielscher for providing quantitative texture analysis software, MTEX for processing EBSD data. We also thank Rick Allmendinger for use of Stereonet 1.2.0.
Group:Caltech Tectonics Observatory
Funders:
Funding AgencyGrant Number
NSFEAR-0739071
Subject Keywords:extrusion; Rand Schist; schist of Sierra de Salinas
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Other Numbering System NameOther Numbering System ID
Caltech Tectonics Observatory129
Record Number:CaltechAUTHORS:20101012-112134099
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20101012-112134099
Official Citation:Chapman, A. D., S. Kidder, J. B. Saleeby, and M. N. Ducea (2010), Role of extrusion of the Rand and Sierra de Salinas schists in Late Cretaceous extension and rotation of the southern Sierra Nevada and vicinity, Tectonics, 29, TC5006, doi:10.1029/2009TC002597.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:20402
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:24 Nov 2010 22:55
Last Modified:07 Aug 2014 21:04

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