Vorticity Estimation of the Terrane Boundary Shear Zone of the Eastern Ghats Mobile Belt, and its Tectonic Significance

ABSTRACT The Terrane Boundary Shear Zone (TBSZ) of the Eastern Ghats Mobile Belt on the NW front against Bastar Craton shows northwesterly vergent thrust kinematics; and on the northern front with Singhbhum Craton shows dextral strike-slip tectonics. The kinematic vorticity numbers are as follows: the NW front, Wm(RGN) is 0.70–0.83 and Wm (Rs/ θ ) is 0.82–1.0; and the northern front, Wm(RGN) is 0.60–0.81 and Wm(Rs/θ) is 0.61–1.0. The estimates suggest that the Wm (Rs/ θ ) values are larger which indicates that the last incremental strain is dominated by simple shear. Further, both fronts are deformed by transpressional to simple shear deformation. However, the northern boundary shear zone has a transtensional component suggesting the TBSZ has undergone shear zone perpendicular extension. The development of the Mahanadi rift valley on the northern front may be related to such extension.