Upendra Man Singh Pradhan and Shardesh Raj Sharma

Petroleum Exploration Promotion Project, Department of Mines and Geology

Lainchaur, Kathmandu, Nepal

The pre-Siwalik sediments are exposed in the inner Terai valley of central Nepal. The sediments occur within the Lower Siwalik and lie to the north of Marin Thrust.  Slices of pre-Siwalik sediment might have brought up by thrusts. Since no fossils have been reported from these pre-Siwalik rocks, their age is referred to range from Gondawana to Miocene.

In this paper, an attempt is made to determine the stratigraphic position and age based on the palynological study. A number of spores and pollen are recorded from the samples. However, the palynomorph assemblages in the samples include only stratigraphically long-ranging taxa (Eocene to Quaternary). The identified Compositae type along with Aabiespollenites, Caryapollenities, Psilamonocolpites, Retitricopites etc are found belonging to Miocene or younger. Zoncostites ramonae (mangrove)  is assigned to be Late Eocene or younger age where as the Dinocyst Lingulodinium machaerophorum suggests the sample belonging to Tertiary or younger. Besides the pre-Siwalik outcrops are lithologically correlable with the red beds of Murree of India and Pakistan that are assigned as Oligocene-Miocene age. Hence, considering the palynomorph assemblages, its recommended age and paleo-environment   including the lithological correlation, the pre-Siwalik sediments of the present area must have deposited in Tertiary time and probably may range from Oligocene to Miocene.