Tectonics of East Indian Subcontinent: As derived from Integrated Gravity Anomalies of India, Bangladesh, Bay of Bengal and Myanmar Regions

Abstract

The East Indian Subcontinent (EISC) is a geologically complex region recording tectonic evolution from the Proterozoic era to the present. This study integrates terrestrial, marine, and satellite gravity data across ∼5 million sq. km covering eastern India, Bangladesh, the Bay of Bengal, and Myanmar, along with earthquake incidences from the past 120 years to unravel the tectonic framework of the region.

A Key focus of this study is building the interrelations among major Proterozoic orogenic belts—Central Indian Tectonic Zone (CITZ), Eastern Ghats Mobile Belt (EGMB), Chhotanagpur Granite Gneissic Complex (CGGC), and Shillong Meghalaya Gneissic Complex (SMGC). From this study, we propose a possible eastern boundary of the CITZ marked as Lucknow–Varanasi–Ranchi lineament, highlight the remarkable affinities between eastern CGGC and EGMB, and redefine the Eastern Continental Margin of India.

Gravity analysis delineates the disposition of collision zones of EISC besides inferring five tectonic domains of EISC, crustal boundaries, plate margins, and transitions from continental to oceanic crust. It also reveals heterogeneity over submarine ridges and the segmentation of the India–Myanmar subduction zone. Aseismic central segment, bounded by cross-faults, is an explicit inference of our study about current Indo-Australian plate subduction dynamics beneath the Sunda–Myanmar Plate.