Abstract

The WNW-ESE trending arm of the Mahakoshal belt, extending towards south-east in the state of Jharkhand, through U.P, exposes variety of structural features those are uncommon in main Mahakoshals having ENE-WSW trend. The turbidites, said to be characteristic of the Parsoi Formation of the WNW trending arm, appear to be shear generated structures, having imprints across the length and width of the arm. Evidences of bulk flow along the pervasive foliation make it a mylonitic foliation, restricting possibility of survival of primary structures

Overwhelming presence of anticlockwise rotated fabric elements, producing S-C structure in phyllite/ phyllonite and in meta-greywacke, along with frequent presence of ‘alpha’ and ‘delta’ type structures, strongly asymmetric ‘S’ and at places ‘Z’ shaped folds and the sheath folds suggest that the ductile shearing with a sinistral shear sense is spread over the entire WNW trending sinuous arm of Mahakoshals. This belt has a strong manifestation on the imagery, maintaining a cross cutting relationship with the ENEWSW trending fabric of the main Mahakoshals and appears to be superposed over it. Evidences suggest it to be a wide and extensive shear zone.

Keywords: Shears; Progressive shearing; Sinistral shear sense; Rotation; Mylonitic Foliation; Turbidit