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Segmentation of the Laramide Slab—evidence from the southern Sierra Nevada region

2003; Geological Society of America; Volume: 115; Linguagem: Inglês

10.1130/0016-7606(2003)115 2.0.co;2

1943-2674

Jason B. Saleeby,

Geology and Paleoclimatology Research

Research Article| June 01, 2003 Segmentation of the Laramide Slab—evidence from the southern Sierra Nevada region Jason Saleeby Jason Saleeby 1Division of Geological and Planetary Sciences, California Institute of Technology, M.S. 100-23, Pasadena, California 91125, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Jason Saleeby 1Division of Geological and Planetary Sciences, California Institute of Technology, M.S. 100-23, Pasadena, California 91125, USA Publisher: Geological Society of America Received: 11 Mar 2002 Revision Received: 24 Jul 2002 Accepted: 24 Sep 2002 First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (2003) 115 (6): 655–668. https://doi.org/10.1130/0016-7606(2003)115 2.0.CO;2 Article history Received: 11 Mar 2002 Revision Received: 24 Jul 2002 Accepted: 24 Sep 2002 First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Jason Saleeby; Segmentation of the Laramide Slab—evidence from the southern Sierra Nevada region. GSA Bulletin 2003;; 115 (6): 655–668. doi: https://doi.org/10.1130/0016-7606(2003)115 2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract During the latest Cretaceous-early Paleogene Laramide orogeny, the lithosphere beneath the southernmost Sierra Nevada batholith and the adjacent Mojave Desert region batholith was sheared off and displaced deeper into the mantle. The lithosphere beneath the greater Sierra Nevada batholith to the north was left intact until mid-Miocene time, when fragments of it were entrained as volcanic xenoliths. The Laramide slab was evidently segmented into a shallow flat segment to the south and a deeper segment to the north. Shearing off of the upper mantle to the south was followed by the tectonic underplating of schists derived from Franciscan subduction complex and possibly forearc basin protoliths. The overlying batholithic crust was deformed, deeply denuded, and tectonically breached westward across its forearc region while the schists were underplated. Westward breachment resulted from a combination of west-directed thrusting and extensional collapse. The westernmost breached rocks were tectonically removed by a combination of trench linked transform and subduction erosion processes. Subsequent tectonic erosion by the Neogene San Andreas transform has left the Salinia and the San Gabriel terranes as dispersed residual fragments of the westward breached arc segment.The shallow slab segment appears to have been ∼500 km in width, measured along the plate edge. To the south, the slab descent appears to have remained deep beneath the Peninsular Ranges batholith. Classic Laramide structures of the craton are concentrated in a corridor that corresponds to the shallow slab segment as defined by plate edge relations and the corresponding trajectory of Farallon–North American relative plate motions when viewed on a pre-Neogene palinspastic base. The plate interior is suggested to have been deformed first by end loading as the shallow slab segment initially descended beneath the plate edge, and then by greater basal traction components as the shallow segment progressed beneath the cratonic region. The subcontinental mantle lithosphere beneath the cratonic deformation zone remained intact through Laramide time.Similar segmented slab topologies have been resolved beneath the modern Andean orogen where the shallow segments are correlated with the subduction of aseismic ridges. A number of researchers have suggested that the Laramide orogeny arose from the subduction of a counterpart of the Hess-Shatsky large igneous province of the northwest Pacific basin. Fragments of rock assemblages that are correlative to the Hess-Shatsky province that were accreted to the Franciscan complex in Laramide time support this view. Recognition of the resulting shallow slab segment and its trajectory beneath North America explains the geographic focusing of Laramide deformation, relative to the rest of the Cordilleran orogen, and the relationships between plate edge and plate interior deformational regimes. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.