Litho-Biostratigraphy of Siwalik Sediments in Arun Khola Area in Nawalparasi and Palpa Districts, Western Nepal.

Abstract

The study area located in the Nawalparasi and Palpa District of Western Development Region of Nepal. The toposheet No 099-11, 099-12, 099-15 and 099-16 cover whole section of the study area. Geographically the study area extends from longitude 83 0 47’50”E to 83 0 58’11”E and latitude from 27 0 40’2”N to 27 0 44’55”N. The total area covered is 163 sq Km. This desertation is concerned with the lithological and biological study of the mentioned area. This area is lies in the Siwalik Group of the Nepal Himalaya. The lithology of that area is like as the other parts of the Nepal but the naming are in different aspect. The study area covers the detail study of the rock unit between the CCT and MBT. Lithilogically the area is classified as Arung Khola Formation, Binai Khola Formation, Chitwan Formation and Deorali Formation. The Arung Khola and Binai Khola Formation are further divided into three members as Lower, Middle, Upper respectively. In these rock units the grain size is of the formation are increasing from older to younger units. Study of thin section of various location shows that the sandstone is of the arkose, lithic arenite and feldspathic types. The climate of the Siwalik formations is sub humid to humid. Palynologcal study is main parts of this thesis. Many pollen samples prepared and analysis has been done. Altogether 22 taxa belonging to 14 families of plant are documented from the Arung Khola Formation. The Arung Khola Formation is deposited in shallow water depositional basin. These texa are warm loving. Plam are common in the studied sample sho the tropical to sub tropical climate. These pollen represent the age of Late Miocene to early playstocene and climate as sa humid and warm as experienced in Terai area of Nepal today. Geological map, cross-section, columnar section, thin section preparation, pollen sample preparation, Paleocurrent analysis were done during the lab work and disertation preparation time. The paleo current flow from the pebble imbrication is found as S56 0 W around the Khani Damar Area.