Supporting the Tibetan Plateau: Coupling of Surface Topography and Upper Mantle Dynamic Processes
Abstract
The Himalaya-Tibetan plateau region has the highest topography on Earth. Although various mechanisms, such as isostasy, flexure, have been put forward as support for the topography, the role of mantle flow in this region is still contentious. We have used geoid-to-topography ratio (GTR), which can constrain the relation between elevation and sub-lithospheric density variations, to evaluate the role of upper mantle density anomalies in affecting the topography in this region. High GTR (> 6 m/km) along the Himalayas correspond to fast seismic velocities in the upper mantle whereas those in northeastern Tibet correspond to slow seismic velocities. Such close correspondence indicates the influence of deeper sub-lithospheric anomalies in affecting surface observations of geoid and topography. Northeastern Tibet, underlain by low-density anomalies, shows high GTR, suggestive of positive dynamic topography. These conclusions are further supported by observations of long wavelength free-air gravity anomalies and dynamic topography predicted from mantle convection models.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMDI51B0009S
- Keywords:
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- 1031 Subduction zone processes;
- GEOCHEMISTRYDE: 8031 Rheology: crust and lithosphere;
- STRUCTURAL GEOLOGYDE: 8120 Dynamics of lithosphere and mantle: general;
- TECTONOPHYSICSDE: 8124 Earth's interior: composition and state;
- TECTONOPHYSICS