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Epeirogenic transients related to mantle lithosphere removal in the southern Sierra Nevada region, California, part I: Implications of thermomechanical modeling

Saleeby, J. and Le Pourhiet, L. and Saleeby, Z. and Gurnis, M. (2012) Epeirogenic transients related to mantle lithosphere removal in the southern Sierra Nevada region, California, part I: Implications of thermomechanical modeling. Geosphere, 8 (6). pp. 1286-1309. ISSN 1553-040X. http://resolver.caltech.edu/CaltechAUTHORS:20121210-101459332

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Abstract

The putative Pliocene–Quaternary removal of mantle lithosphere from beneath the southern Sierra Nevada region (California, USA) is investigated by the iteration of thermal-mechanical models that incorporate and are tested against a range of data that are geologically observable, including rock uplift and basin subsidence data, structural and compositional data on crustal architecture, and a synthesis of seismic data that image lower crust–upper mantle structure of the region. The primary focus is testing model results with rock uplift and basin subsidence data. The initial state of our models recognizes that (1) the sub–Sierra Nevada batholith mantle lithosphere, including a substantial thickness of eclogitic cumulates that were produced during high magma flux arc activity, termed arclogite, was cooled to a conductive geotherm by amagmatic flat slab subduction at the end of the Cretaceous; and (2) the gravitationally metastable mantle lithosphere was thermally mobilized from beneath in the Neogene by the opening of an underlying slab window. Based on a detailed synthesis of appropriate rheologies of the multiphase system, a preferred class of models correctly predicts (1) the ca. 10 Ma inception of the Sierra Nevada microplate due to a lithospheric separation event along the eastern Sierra Nevada region as a result of the mobilization of the mantle lithosphere as a Rayleigh-Taylor instability; and (2) the subsequent delamination of the arclogite root of the Sierra Nevada batholith that appears to be in progress. Our preferred model also predicts focused rock uplift and basin subsidence resulting from delamination, both of which are anomalous to uplift and subsidence patterns of all other regions of the microplate. The rheology of the Great Valley crust is found to control rock uplift patterns across the Sierra Nevada, and tectonic subsidence in the Tulare Basin of the Great Valley. The Tulare Basin is uniquely situated over the region where the principal residual arclogite root remains attached to batholithic crust. The anomalous rock uplift and tectonic subsidence data are best satisfied by modeling a bulk rheology for the Great Valley crust that is similar to that of the Sierra Nevada batholith. These results are consistent with a recent synthesis of basement core and geophysical data showing that much of the Great Valley basement consists of the western Early Cretaceous zones of the Sierra Nevada batholith. The existence of this batholithic domain within the Great Valley subsurface is also in agreement with recent seismic data that resolve additional residual arclogite root materials along the base of the crust of this region.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1130/GES00746.1 DOIUNSPECIFIED
http://geosphere.gsapubs.org/content/8/6/1286.abstractPublisherUNSPECIFIED
Additional Information:© 2012 Geological Society of America. Received 4 August 2011; Revision received 11 July 2012; Accepted 17 July 2012; Published online 16 November 2012. This research was supported by National Science Foundation grant EAR-0606903, a grant from the George and Betty Moore Foundation, and Faculty Research Funds from the Université Pierre et Marie Curie (France). This is Caltech Tectonics Observatory Contribution 141. Communications with Craig Jones, Jeff Unruh, Mihai Ducea, George Zandt, Don Helmberger, Cyn-Ty Lee, Peter Molnar, Gene Humphreys, and Don Anderson helped stimulate our work.
Group:Caltech Tectonics Observatory, Seismological Laboratory
Funders:
Funding AgencyGrant Number
NSFEAR-0606903
George and Betty Moore FoundationUNSPECIFIED
Université Pierre et Marie Curie (France)UNSPECIFIED
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Caltech Tectonics Observatory141
Record Number:CaltechAUTHORS:20121210-101459332
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20121210-101459332
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:35893
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:18 Dec 2012 16:32
Last Modified:23 Aug 2016 10:22

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