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Abstract:
Understanding of the evolutionary geodynamics of the Eastern Ghats Mobile Belt (EGMB), is crucial to reconstruction of the Rodinia and Gondwana supercontinents. However limited aspects of its structure and evolutional origin are known. Based on lithological assemblage and geochronological data, EGMB is divided into multiple heterogeneously deformed terranes. Recent seismological studies across the EGMB-Archaean craton boundary adds new perspective regarding the deformation of the region and its correlation with East-Antarctica. Integrated studies reveal heterogeneous structure across the craton and mobile-belt characterised by 32-37km, ~42km and 110-160km, 80-120km thick crust and lithosphere respectively, suggesting collisional thrusting of EGMB against the Archean Cratons that explains the abrupt changes in crustal thickness across the craton-mobile belt. The influence of mantle-plumes, owing to the trajectory of the Indian subcontinent across the Kerguelen/Crozet hotspots, results in thinner cratonic-lithosphere than its erstwhile neighbours in the Gondwanan configuration. Observations indicate crustal amalgamation of different blocks in the evolution of the present EGMB, akin to observations from East-Antarctica also touted to be composed of different Proterozoic crustal terranes. Parity in crustal thickness is also noted. Strained minerals along the upper-mantle fabrics influence the variation of anisotropic parameters across different domains, indicating large-scale pervasive deformation related to various collisional-rifting episodes. The most notable being the disparity in anisotropic trends and lithospheric architecture across the eastern and western Phulbani Domain establishing them as separate blocks. Thereby, deeper understanding into the complex geodynamics of EGMB and its correlation with East-Antarctica can be achieved through unified geophysical studies across both the regions.
