The Zagros Core: Deformation of the continental lithospheric mantle

Priestley, K. F. and McKenzie, D. P. and Barron, J. and Tatar, M. and Debayle, E. (2012) The Zagros Core: Deformation of the continental lithospheric mantle. Geochemistry Geophysics Geosystems - GCubed, 13 (11). Q11014. ISSN 1525-2027 DOI https://doi.org/10.1029/2012GC004435

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Abstract

The Zagros of Iran form one of the youngest collisional orogenic belts on Earth. At shallow depths, shortening across the Zagros is accommodated by folding in the sediments, high-angle thrust faulting in the basement and thickening of the lower crust, but how shortening is accommodated by the lithospheric mantle has been uncertain largely because the upper mantle seismic structure has been poorly known. We map the lateral variations in upper mantle shear-wavespeed beneath this region using a large, multi-mode surface wave data set. The upper mantle is slow for most of the Middle East, but a high shear-wavespeed lid extending to ~225km depth exists beneath the Zagros. We use a T(Vs,z) relation to convert the shear-wavespeed profiles to temperature profiles and fit these with geotherms to identify the base of the lithosphere. The upper mantle temperatures from the seismic model are consistent with temperatures derived from geochemical modeling. The lithosphere is less than ~120km thick over the region except for a thick lithospheric root beneath the Zagros, implying that shortening in the mantle is accommodated by lithospheric thickening. The composition of the volcanic rocks from above the area of the thickened lithosphere has depleted magma source regions with densities ~60kg/m3 less than the MORB source. Elsewhere in the Middle East the volcanic source regions have compositions and densities similar to that of MORB. The shortening across the Zagros is accommodated by lithospheric thickening but the cool thickened lithosphere has been stabilized from delamination by depletion.

Item Type:	Article
Additional Information:	©2012. American Geophysical Union. All Rights Reserved.
Uncontrolled Keywords:	2012AREP; IA64;
Subjects:	02 - Geodynamics, Geophysics and Tectonics
Divisions:	02 - Geodynamics, Geophysics and Tectonics 12 - PhD
Journal or Publication Title:	Geochemistry Geophysics Geosystems - GCubed
Volume:	13
Page Range:	Q11014
Identification Number:	https://doi.org/10.1029/2012GC004435
Depositing User:	Sarah Humbert
Date Deposited:	15 Oct 2012 07:56
Last Modified:	07 Jan 2019 12:49
URI:	http://eprints.esc.cam.ac.uk/id/eprint/2603

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