Himalayan transverse faults and folds and their parallelism with subsurface structures of North Indian plains

Abstract

A large number of fractures, faults and folds trending normal and oblique to the Himalayan tectonic trend have been recognized in recent years. The tear faults of Kumaun and Nepal have caused predominant right-lateral shear movements. There are eloquent indications of tectonic and seismic activities along some of these faults. In Kumaun, some of the NNW-SSE oriented tear faults coincide with the great thrusts that have brought older Precambrian crystallines over the sedimentary rock. This phenomenon has led many workers to interpret the thrusts as high-angled faults. Significantly, these transverse and oblique faults and fractures are parallel to the great faults discovered in the basement of the Ganga Basin and in the South Indian block, implying a certain genetic connection between the two sets. Likewise, the transverse folds of mesoscopic and macroscopic dimensions superposed on earlier folds of normal Himalayan trend are parallel to the great hidden ridges in the base ment of the Ganga Basin, representing undersurface extension of the Peninsular orogenic trends such as the Satpura, Bundelkhand and Aravali. The presence in the Lesser Himalaya of transverse structures having striking parallelism with those of Peninsular India, coupled with the strong lithostratigraphic similarities between the Purana (Riphean) sedimentary formations of the Lesser Himalaya and the greater Vindhyan Basin and the occurrence in many parts of the Himalaya of coalbearing continental Gondwana and marine Permian formations, reminiscent of similar horizons of the Bihar-Madhya Pradesh borders, is a pointer to the tectonic unity of the two provinces and suggests involvement of Peninsular India in the tectonic framework of the Himalaya.