Geological and Tectonic analysis of Shivalik range of northwestern Himalayas

Abstract

The fluvial sedimentary rocks deposited in the basins located to the south, facing the Himalayan orogenic chain, are known as the Siwalik Group. The study area of ​​the present work, located in the foothills of the northwestern Himalayan region, villages Saketi and Kala Amb, Sirmaur district, Himachal Pradesh, exposes rocks from various units of the Lower, Middle, and Upper Siwalik subgroups. Based on the environmental conditions of deposition, these sediments are interpreted as continental deposits, characterized by fluvial deposits, alluvial fan deposits, and lake-borne deposits. Since the early nineteenth century, the rocks of the Siwalik Group have also been recognized for their rich and diverse fossil collection of fauna, especially vertebrates. Based on the study of the biological evolution of these fossils, the rocks of this age have been placed in the Middle Miocene-Pliocene-Pleistocene period. Signs of tectonic and neo-tectonic activity are also visible in the rocks of these Shivalik ranges at many places, the main ones being the Himalayan Frontal Thrust/Fault (HF T/F) in the south and the Nahan Thrust (NT) along with the Main Boundary Thrust/Fault (MBF) in the north.