Discrepant crustal deformation beneath the Pamir revealed by joint inversion of surface wave dispersion and receiver function
Abstract
The Pamir Plateau, situated north of the western Himalayan syntaxis, has presumably been moving north relative to the surrounding regions since about 25 Ma and overriding the crust which previously connected the Tajik Depression in the west and the Tarim Basin in the east. Considering the relation of present to pre-Cenozoic crustal thicknesses, the huge amounts of crustal shortening and thickening leaded to significant crustal deformation in the Pamir. Receiver function research and ambient noise tomography, as useful methods to constrain crustal structures, have revealed lower crustal subduction (Schneider et al, 2013) and mid-crustal LVZs (Chen et al, 2018) beneath the Pamir, respectively. Based on data from temporary networks (e.g., TIPAGE, FERGHANA) and permanent stations, we applied the joint inversion of surface wave dispersion and receiver function to obtain high resolution crustal structures beneath the Pamir. The joint inversion could integrate resolution advantages of receiver function research and ambient noise tomography to reconstruct more detailed crustal structures, and would be helpful to understand mechanisms of discrepant crustal deformations and their relationship with deep processes. As revealed by our results, northeastern and southwestern Pamir both show relatively lower mid-crustal S-wave velocities than other mid-crustal LVZs in the Pamir. While subducting angles and Moho topographies are discrepant beneath these two areas, steeply subducting and deep Moho beneath the southwestern Pamir, and gently subducting and shallow Moho beneath the northeastern Pamir. Comprehensive analysis with tectonic and thermochronological results, we interpreted these discrepancies as results of arc-shaped delamination of the Pamir's lithosphere caused by northward underthrusting of the Indian cratonic lithosphere. And asthenospheric upwelling related to the delamination significantly contributes to the mid-crustal lower S-wave velocities beneath northeastern and southwestern Pamir.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.T24A..05L
- Keywords:
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- 0925 Magnetic and electrical methods;
- EXPLORATION GEOPHYSICSDE: 7218 Lithosphere;
- SEISMOLOGYDE: 8104 Continental margins: convergent;
- TECTONOPHYSICSDE: 8123 Dynamics: seismotectonics;
- TECTONOPHYSICS