The Moho beneath western Tibet: Shear zones and eclogitization in the lower crust
File(s)
Author(s)
Type
Journal Article
Abstract
The Tibetan Plateau is formed by continuing convergence between Indian and Asian plates since ∼50 Ma, involving more than 1400 km of crustal shortening. New seismic data from western Tibet (the TW-80 experiment at 80°E) reveal segmentation of lower crustal structure by the major sutures, contradicting the idea of a mobile lower crust that flows laterally in response to stress variations. Significant changes in crustal structure and Moho depth occur at the mapped major tectonic boundaries, suggesting that zones of localized shear on sub-vertical planes extend through the crust and into the upper mantle. Converted waves originating at the Moho and at a shallower discontinuity are interpreted to define a partially eclogitized layer that extends 200 km north of the Indus–Yarlung Suture Zone, beneath the entire Lhasa block at depths of between 50 and 70 km. This layer is thinner and shallower to the north of the Shiquanhe Fault which separates the northern Lhasa block from the southern part, and the degree of eclogitization is interpreted to increase northward. The segmentation of the Tibetan crust is compatible with a shortening deformation rather than shear on horizontal planes. Unless the Indian-plate mantle lithosphere plunges steeply into the mantle beneath the Indus–Yarlung suture, leaving Indian-plate crust accreted to the southern margin of Tibet, then it too must have experienced a similar shortening deformation.
Date Issued
2014-12-15
Date Acceptance
2014-10-13
Citation
EARTH AND PLANETARY SCIENCE LETTERS, 2014, 408, pp.370-377
ISSN
0012-821X
Publisher
ELSEVIER SCIENCE BV
Start Page
370
End Page
377
Journal / Book Title
EARTH AND PLANETARY SCIENCE LETTERS
Volume
408
Copyright Statement
© 2014 Elsevier B.V. All rights reserved. NOTICE: this is the author’s version of a work that was accepted for publication in Earth and Planetary Science Letters . Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in EARTH AND PLANETARY SCIENCE LETTERS, Vol.: 408, (2014) DOI: 10.1016/j.epsl.2014.10.022
Description
28.04.15 KB. Ok to add accepted version to spiral, subject to 24 months embargo
Identifier
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Subjects
Science & Technology
Physical Sciences
Geochemistry & Geophysics
Tibetan Plateau
Moho segmentation
receiver functions
crustal thickness
eclogitization
shear zones
INDIAN LITHOSPHERE BENEATH
COLLISION ZONE
UPPER-MANTLE
SEISMIC VELOCITIES
PLATE BENEATH
HIMALAYA
EVOLUTION
SUBDUCTION
EXTRUSION
TOMOGRAPHY
Publication Status
Published