Crustal-scale duplexing beneath the Yarlung Zangbo suture in the western Himalaya

doi:10.13745/j.esf.sf.2021.7.10

Abstract

Abstract:

The fate of the Indian plate during continental collision with Asian terranes, and the proportion of the Indian crust that is underthrust or subducted beneath Tibet as opposed to transferred to the upper (Himalayan) plate, are much debated. The active geometry of low-angle underthrusting or subduction of the Indian plate beneath the Lesser and Greater Himalayan thrust sheets is well known from seismic imaging. Previously, only images with lower resolution have been obtained in the Main Himalayan Thrust beneath the Yarlung Zangbo suture that separates Indian and Asian rocks at the surface. It remains controversial whether the orogenic wedge between the Main Himalayan Thrust and the Yarlung Zangbo suture, formed of Indian crust transferred to the upper plate, is evolving by thrust-faulting in a critical-taper wedge or by southward extrusion of a ductile channel flow. Here we present a seismic reflection profile across the western Himalaya at 81.5°E, and show that the Main Himalayan Thrust dips 20 to 60 km depth beneath the Yarlung Zangbo suture, approaching a continuous Moho reflection at 70-75 km depth. The Indian crust being transported northwards beyond the Yarlung Zangbo suture is no more than 15 km thick, reduced from its original 40 km thickness by transfer of material from the lower plate to the upper plate through crustal-scale duplexing.

Key words: duplexing, crustal structure, deep seismic reflection profile, Yarlung Zangbo suture, the Tibetan Plateau

CLC Number:

P542
P631.4

LU Zhanwu, GAO Rui, Simon KLEMPERER, WANG Haiyan, DONG Shuwen, LI Wenhui, LI Hongqiang. Crustal-scale duplexing beneath the Yarlung Zangbo suture in the western Himalaya[J]. Earth Science Frontiers, 2022, 29(2): 210-217.

Figures/Tables 3

References 37

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