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  • On the relationship between the uppermost mantle (≤220 km) seismic velocity, crustal thickness, and topography in Tibet

This content will become publicly available on November 20, 2025

Title: On the relationship between the uppermost mantle (≤220 km) seismic velocity, crustal thickness, and topography in Tibet
Abstract We propose that the mantle lithospheric density and crustal thickness are correlated in such a way as to produce a flat Tibetan Plateau. We observe that the mantle lithosphere is relatively uniform beneath the Himalaya and southern and central Tibet, despite a near doubling of crustal thickness relative to India. Farther north, cratonic mantle lithosphere disappears over large regions of north-central Tibet, giving rise to large lateral variations in uppermost mantle Vs anomalies (>12%) that are uncorrelated with changes in surface elevation but are closely related to changes in crustal thickness. This decoupling of surface topography from spatial variations in upper mantle seismic velocity, and assumed buoyancy, implies that Tibetan topography is controlled by a crust-mantle interaction that is able to maintain its near constant elevation. This crust-mantle interaction is likely driven by gravitational potential energy with a very weak crust. Magmatism, with ages of ca. 20 Ma to Present, spatially correlated with this region with no sub-Moho mantle lithosphere implies destabilization of mantle lithosphere in northern Tibet. Cratonic Indian underthrusting for the past 25 m.y. has also not led to significant topography in the plateau through time. The magmatism may have helped weaken the crust, allowing it to respond to changes in uppermost mantle buoyancy, resulting in a flat plateau.  more » « less
Award ID(s):
1838376
PAR ID:
10570975
Author(s) / Creator(s):
; ; ; ;
Publisher / Repository:
Geological Society of America
Date Published:
Journal Name:
Geology
Volume:
53
Issue:
2
ISSN:
0091-7613
Page Range / eLocation ID:
166 to 170
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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