| Abstract Submission No. | ABS-3.1-0192 |
| Title of Abstract | Shear wave structure and stress field of the Lithosphere beneath the Hindukush-Pamir region: Geodynamic implications |
| Authors | Naresh Kumar* |
| Organisation | Wadia Institute of Himalayan Geology |
| Address | Anushai Kumar D/o Naresh Kumar Dehradun, UTTARAKHAND, India Pincode: 248007 E-mail: nkd@wihg.res.in |
| Country | India |
| Presentation | Oral |
| Abstract | Systematically image the salient lithosphere structure and stress regimes beneath the Hindukush and Pamir regions. High-resolution surface wave tomography delineates the fine structure of the Lithosphere, and the stress regime patterns at different depths are elucidated through the inversion of focal mechanisms. Tomography indicates a low-velocity zone within the Lithosphere expressing the undergoing continental crust along with the mantle as the subducting slab. In the Hindukush region, the seismicity is concentrated up to 280 km depth with three distinct depth zones (up to 70, 70-160 and 160-280 km). Deeper earthquakes extend from the southwest in the southern part of the Hindukush to a maximum depth of ~150 km. In the central part of the Hindukush, they plunge to a depth of ~250 km, decreasing towards the central Pamir, and finally, this deeper depth seismicity diminishes towards the northeast beneath eastern Pamir. These intermediate focal depth earthquakes delineate slab plunging down and suggest an isolated stable block beneath the Hindukush, a distinctive nature of tectonic collision. The clockwise rotation of the largest principal stress in the compressive regimes with respect to increasing depth reflects the rotational behaviour of the subducted slab with the increase in depth. Simultaneously, in the Pamir region, anticlockwise rotation of principal stress together with a change in stress regimes with respect to increasing depth has been perceived as a complex collision geometry. An effective conceptual model that highlights the depth-wise regional stress environment is provided by the seismicity and Stress Tensor Inversion results in the Hindukush-Pamir regions. Also, the S-wave velocity tomography investigation indicates a very clear signature of submerging of the lithosphere structure of the Indian and Asian plate beneath the Hindukush-Pamir. The present work and data provide effective information on the IndiażAsia collision, and additional data in the future will strengthen the results. |
| Keywords | Hindukush-Pamir, Shear wave structure, stress field, Subducted slab, Seismcity |