Structure and Attenuation of the Continental Crust

Das, Prajna Paramita (2022) Structure and Attenuation of the Continental Crust. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (MS dissertation of Prajna Paramita Das (17MS045)) 17MS045_Thesis_file.pdf - Submitted Version Restricted to Repository staff only Download (22MB)

Abstract

This work comprises two projects, one, to compute the sediment layer thickness, Moho depth and well-constrained models of the crustal structure beneath the Ganga basin; the other to map the lateral variations in seismic-wave propagation (P-wave attenuation) characteristics of the Jammu and Kashmir Himalaya. We have obtained sediment thickness of around ∼ 4 km and the Moho depth ranging between 44 to 50 km underneath the Ganga basin. The thickness of the sedimentary strata and shear wave velocity structure of the crust and uppermost mantle beneath these foreland basins are important to understand the strength and deformation of the Indian plate as it underthrusts the Himalaya and Tibetan plateau. Our results are compared with studies done on the northeastern Himalayan foreland basin. P-wave attenuation tomography is computed for the Jammu and Kashmir Himalaya. A seismic gap lies in the region. Attenuation tomography is a sensitive indicator of tectonic processes. So apart from computing the P-wave attenuation tomography of our region of interest we have also tried to correlate our results with the active tectonics of the region. South-west of the Kishtwar window showed distinct low values of Q which is presumed to be an effect of the presence of frontal and lateral ramps. Shiwaliks displayed intermediate Q values followed by high values for the Tethyan Himalayas.

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