Structure of the Nagavali Shear Zone, Eastern Ghats Mobile Belt, India: Correlation in the East Gondwana Reconstruction

Abstract

Interpretation of satellite data in combination with regional field traverses, delineating the major structural features such as the Nagavali and Vamsadhara Shear Zones and associated fold patterns, provides a synoptic picture of the regional tectonic framework of the central part of the Eastern Ghats Mobile Belt. The complex geology of the study area can broadly be grouped into three distinct deformational events. D 1 fabrics represented by near flat-lying gneissic foliations, paralleling the lithological banding are best preserved in low strain domains and are related to Middle to late Archaean thrusting (3000-2600 Ma). The second deformational event D 2 is characterized by the development of shear zones and associated mylonitic fabrics and magmatism probably during 1450-850 Ma. The Pan-African thermal (500-550 Ma) overprint is restricted to shear zones in the form of reworking. Regionally, the central part of the Eastern Ghats Mobile Belt can be divided into five distinct structural domains based on structural geometry of folds, foliations and lineations. A three-dimensional block diagram of the Nagavali and Vamsadhara Shear Zones involving fold-thrust tectonics associated with westward thrusting is presented here. A correlation of Pan-African Shear Zones in adjacent continents wrapping around the Archaean Dharwar Craton in the reconstruction of Rodinia and East Gondwana supercontinent suggests an east-west convergence.