CALCAREOUS NANNOFOSSILS OF ALBIAN AGE FROM TANOT WELL1, JAISALMER BASIN, RAJASTHAN AND ITS PALAEOBIOGEOGRAPHIC SIGNIFICANCE

The present paper deals with the record of well preserved and diverse early-middle Albian nannofossils recovered from Tanot # 1 (Oil India Limited), drilled in the Jaisalmer Basin, Rajasthan, western India. Early Cretaceous (Aptian-Albian) marine sediments are known from the western (jaisalmer and Kachchh basins) and the eastern continental margins (Mahanadi, Krishna-Godavari, Palar and Cauvery basins) of the Indian Plate. Early-middle Albian nannofossils are known from sandy, fossil-fauna depleted; Upper Member of Bhuj Formation in Kachchh (Biswas, 1977). Aptian to Turonian nannofossils are recorded from fossiliferous Cauvery Basin, southern India. The Tanot #1 samples are available from 1104-1899m depth; however, only a part of the interval between depths 1899m-1596m is studied herein. The occurrence of Tranolithus orionatus from the oldest sample (1899m) upwards is used here to assign it to CC8 Zone (Sissingh, 1978) and NC8 Zone (Roth, 1978) of middle Albian age. FAD of T. orionatus is a middle Albian marker both in the Tethyan and the Boreal provinces in various zonation schemes. FAD of Axopodorhabdus albianus at 1656m marks base of NC9 Zone (Roth, 1978) in the section as well. The dominance of Nannoconus spp. suggests shallow water environment and nearness to shore.