Imaging the lithospheric structure beneath the Indian continent
|Author(s)||Maurya S.1, Montagner J-P1, Kumar M. Ravi2, Stutzmann E.1, Kiselev S.3, Burgos G.1, Rao N. Purnachandra2, Srinagesh D.2|
|Affiliation(s)||1 : Inst Phys Globe Paris, Paris, France.
2 : Natl Geophys Res Inst, Hyderabad, Andhra Pradesh, India.
3 : Inst Phys Earth, Moscow, Russia.
|Source||Journal Of Geophysical Research-solid Earth (2169-9313) (Amer Geophysical Union), 2016-10 , Vol. 121 , N. 10 , P. 7450-7468|
|WOS© Times Cited||55|
We present a high-resolution 3-D lithospheric model of the Indian plate region down to 300 km depth, obtained by inverting a new massive database of surface wave observations, using classical tomographic methods. Data are collected from more than 550 seismic broadband stations spanning the Indian subcontinent and surrounding regions. The Rayleigh wave dispersion measurements along similar to 14,000 paths are made in a broad frequency range (16-250 s). Our regionalized surface wave (group and phase) dispersion data are inverted at depth in two steps: first an isotropic inversion and next an anisotropic inversion of the phase velocity including the SV wave velocity and azimuthal anisotropy, based on the perturbation theory. We are able to recover most of the known geological structures in the region, such as the slow velocities associated with the thick crust in the Himalaya and Tibetan plateau and the fast velocities associated with the Indian Precambrian shield. Our estimates of the depth to the Lithosphere-Asthenosphere boundary (LAB) derived from seismic velocity V-sv reductions at depth reveal large variations (120-250 km) beneath the different cratonic blocks. The lithospheric thickness is similar to 120 km in the eastern Dharwar, similar to 160 km in the western Dharwar, similar to 140-200 km in Bastar, and similar to 160-200 km in the Singhbhum Craton. The thickest (200-250 km) cratonic roots are present beneath central India. A low velocity layer associated with the midlithospheric discontinuity is present when the root of the lithosphere is deep.