Uppermost Mantle Seismic Velocity and Anisotropy Structure beneath the Indian Shield and Adjacent Regions

Abstract

Abstract newlineThe tectonic framework of the Indian Shield is a complex amalgamation of diverse newlinegeodynamic regimes, namely orogenic belts (the Himalayas and Tibetan region), cratons and newlinebasins inside the Indian Shield, oceanic and continental subductions (Burmese, HindukushPamir, newlineand newlineAndaman-Nicobar newlineIsland newlinearcs), newlineand newlinethe newlineoceanic newlineplate newline(the newlineBay newlineof newlineBengal). newlineThe newlinestudy newlineregion newlineextends newlinebetween newline5.5ºS newlineand newline45ºN, newlineand newline55ºE newlineand newline105ºE. newlineThe newlineIndian newlineShield newlineis newlinemostly newline made up of a mosaic of Precambrian crystalline terrains with their evolutionary newlinehistories. Cratons, rifts, deep sedimentary basins, accreted terranes, and the widespread newlineDeccan volcanic province are all situated within the plate interior. After the breakup of newlineGondwanaland, several mantle plume episodes significantly altered the Indian lithospheric newlineplate. The Himalayan arc marks the northern limit of the Indian plate, where the Indian plate newlineis underthrusting continually beneath the Eurasian plate. The continental Indian plate is newlineobliquely underthrusting the Myanmar (Burma) microplate along the Burmese arc in the newlinenortheast. The geodynamic processes and features related to the Indian lithosphere and the newlinesubduction in this region are controversial, such as the effect of the collision on the Indian newlineplate, the thickness and anisotropic nature of the plate, coupling or decoupling of the upper newlinemantle, the state of the mantle lid, the nature of the oceanic plate (the Bay of Bengal), etc. newlineThe significant velocity variation between the crust and the mantle enables efficient newlinepropagation of Pn and Sn waves through the uppermost mantle, which is often modelled as a newlinehead wave, and thus assists in strongly constraining tomographic models. For this purpose, Pn newlineand Sn wave arrivals were utilized to generate the high-resolution P- and S-wave velocities, newlineVp/Vs ratios, and anisotropy models of the hitherto elusive uppermost mantle beneath the newlineIndian Shield and its surrounding regions to unravel the tectonic imprints in the litho