Collaborative Research: Lithosphere-Scale Dynamics of Active Mountain Building Along the H imalayan-Tibetan Collision Zone

Oregon State University, Corvallis OR

Investigators

Abstract

9909609 Nabelek The overall goal of this project is to determine exactly how the continental lithosphere deforms over its entire thickness during the building of the Himalayas. The P.I.s will deploy a unique 700 km. long, high-density broadband seismic transect across the Himalaya-Tibetan Plateau in cooperation with Nepalese, Chinese, French and German collaborators. The results will be used to determine which of three competing models is more appropriate: 1) Indian lithosphere underthrusts Tibet with little deformation, 2)Himalaya is a sequence of thrust stacks that involve the entire crust and uppermost mantle, or 3) Both crust and uppermost mantle shorten appreciably and the crust is weak between them. The project will provide the critical information that is missing at depth beneath key segments of the collision zone, and will map out the geometry and kinematics of prominent crustal, Moho, and upper mantle interfaces that are key for understanding how the mantle is linked to portions of the lithosphere. Specific research targets include: Mantle-involved deformation in the Himalayan foreland - how deep does the deformation go; the configuration of various thrust surfaces at depth and how the thrusts work; and the structure of the Yarlung-Zangpo suture zone its northward extent and the fate of the underthrust Indian lithosphere. ***