Deep crustal Shear Zones in the Eastern Ghats Mobile Belt, India: Gondwana correlations

Shear zones are significant in understanding the physicochemical processes, such as mineralization, magmatism, metamorphism, and deformational patterns and bear remarkable influence on many aspects of earth system science. We present here the structural framework of the Eastern Ghats Mobile Belt (EGMB) that constitutes a net work of deep crustal shear zones. It was possible to identify and recognize these shear zones by involving different spatial data sets, field observations along regional traverses and detailed structural analysis in selected critical areas and outcrop mapping and in conjunction with the available published geological maps. We review and present here field description, distribution, geometry and the kinematics of different shear zones of the EGMB and emphasize their significance in terms of tectonic models and Gondwana correlations. The shear zones at the cratonic margins such as the Sileru shear zone, Koraput - Rairakhol shear zone and the Northern boundary shear zone represent a long and continuous suture zone extending for over a few hundreds of kilometers and upto lithospheric depths. All the shear zones witnessed multiple events of magmatism, metamorphism and deformation. The stretching lineations show different orientations in different segments and divide the EGMB into several distinct structural domains. All the shear zones are found to be transpressive in character and subjected to repeated reactivation in space and time. Oblique collision and long lived transpressional tectonic regime during Gondwana amalgamation seem to be responsible for the present structural architecture of the EGMB. The shear zones are the controlling factors for any mineralization, igneous activity, migmatization and retrogression and that they represent key laboratories' for understanding the geological processes and ultimately the earth's history. There is a strong need for detailed field based studies involving modern mapping techniques with current tectonic perspectives before we attempt any advanced laboratory based measurements for useful and meaningful interpretations.