Modification of fold geometry in Almora Crystalline Shear Zone, Lesser Himalaya, India

Abstract

The folds generally initiate at several discrete points along a layer or multilayer undergoing compressional forces. These compressional forces often lead to rotation of fold segments and in all such regimes, folds are strongly asymmetrical and are in complete agreement with the direction in which the force is applied and also with the related thrust sheet movement. This paper illustrates the progressive change in fold geometry with increasing compression and ductile shearing using natural example as studied in the Almora Crystalline Zone (ACZ). The folds in the ACZ have started developing initially by the buckling processes as upright folds with varying degrees of inter-limb angles, which later on with increasing amount of ductile shearing modified in to tight to isoclinal and overturned to recumbent folds.