| Abstract Submission No. | ABS-4.1-0132 |
| Title of Abstract | Lithospheric Deformation and Depth Localization of Seismic Anisotropy Beneath the Sikkim Himalaya |
| Authors | SATYAPRIYA BISWAL*, Debasis D Mohanty |
| Organisation | CSIR- North East Institute of Science and Technology |
| Address | AT-BENA, PO-KHUNTAPADA Keonjhar, Odisha, India Pincode: 758019 E-mail: satyapriyabiswal8763@gmail.com |
| Country | India |
| Presentation | Oral |
| Abstract | Seismic anisotropy serves as a powerful tool for deciphering the strength, direction, and depth of deformation within the crust, lithosphere, and sub lithospheric mantle. This study integrates shear wave splitting (SWS) analyses and spatial coherency methods to unravel the crustal¿mantle deformation patterns and source localization of anisotropy beneath the Sikkim Himalaya. Using the core refracted (SKS/SKKS/PKS) and crustal (Direct-S) seismic phases, this work presents novel shear wave splitting (SWS) observations from the Sikkim Himalaya region to understand the deformation patterns at the mantle and crustal scales, respectively. Indo-Eurasian collisional tectonics dominates the deformation patterns beneath Sikkim, as evidenced by significant time delays (δt) and consistent NW-SE orientated fast polarisation directions (ϕ) at all seismic station locations. The Sikkim Himalayan region has a similar crustal deformation pattern (NE-SW), driven by the alignment of maximum shear stress, indicating that the correlated crust-mantle dynamics are influenced by the massive collisional tectonic force. Spatial coherency analysis of splitting parameters based on the Fresnel zone concept was used to further constrain the source and depth of anisotropy. The findings point to a central anisotropic layer at a depth of around 120 km, which is indicative of deformation in the intricate lithospheric mass beneath Sikkim. This work collectively signifies that the lithospheric deformation beneath the Sikkim Himalaya is governed by large-scale collisional tectonics, manifested through the interaction of crust¿mantle anisotropy and deep-seated heterogeneities that reflect active geodynamic processes along the eastern Himalayan orogenic belt. |
| Keywords | Sikkim Himalaya, Seismic Anisotropy, Shear Wave Splitting, Lithospheric Deformation, Convergence tectonics, Indo-Eurasia collision |