S-Wave Tomographic Structure of NE India Using Rayleigh Wave Group Velocity
Abstract
Tomographic images of crust and upper mantle of NE India and its surroundings were obtained by inversion of Rayleigh wave data recorded at local and regional distances by a dense seismic network. The images reveal thick layer of sediments in Bengal Basin, thickness increases from ~10 km at its western end to ~21 km at its eastern end. The basement of sediments suddenly becomes steeper on the eastern side of Eocene Hinge zone. Indo-Gangetic Plains and Brahmaputra River valley also comprise of low velocity medium of ~5-6 km thick sediments. Crustal thickness in the higher Himalayas and southern part of Tibet is ~70 km whereas its value varies between ~30 km to ~40 km in the remaining part of the study area. Crust and upper mantle below Shillong plateau and Mikir hills bend upwards. This may represent a pop up structure or the crest of buckled up Indian plate. Patches of low velocity medium is present in the lower crust of southern Tibet which indicates presence of either partially molten material or aqueous fluid. These patches of low velocity occur between the Kung-Co and Yadong-Gulu rift zones and to the east of Yadong Gulu rift zone. Also, the Moho depth changes from ~75 km to the west of Yadong Gulu rift zone to ~60 km to its east indicating the complicated effect of underthrusting of the Indian plate below the Eurasian plate.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.T51D0293M
- Keywords:
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- 8011 Kinematics of crustal and mantle deformation;
- STRUCTURAL GEOLOGY;
- 8110 Continental tectonics: general;
- TECTONOPHYSICS;
- 8169 Sedimentary basin processes;
- TECTONOPHYSICS;
- 8175 Tectonics and landscape evolution;
- TECTONOPHYSICS