Structural Geometry of the Rocks of the Southern Part of the Nallamalai Fold Belt, Cuddapah Basin, Andhra Pradesh

A sequence of quartzite, banded phyllite and slate in the southern part of the Nallamalai fold belt shows a series of macroscopic gently plunging folds (DI) with NW-SE striking axial plane and a pervasively developed axial planar slaty cleavage. A weak later deformation has produced sporadic gentle folds (D2) with axial planes at high angle to the D1 fold axial planes.

The rocks along the eastern contact of the belt are mylonitized and the intensity of deformation gradually dies away towards west. A zone of tectonic dislocation is envisaged between the basement granite gneiss towards the east and the supracrustal Nallamalai rocks.