Early to Middle Albian age calcareous nannofossils from Pariwar Formation of Jaisalmer Basin, Rajasthan, western India and their significance

Early-Middle Albian calcareous nannofossil assemblage comprising 55 species has been recovered from the Pariwar Formation, Jaisalmer Basin, western India. The nannofossils are moderate to well-preserved and are calibrated with Early-Middle nannofossil zones CC7-CC8 of Albian age. The present record of nannofossils indicates a marine depositional environment with good connection to the open ocean for the Pariwar Formation. Presence of species, Seribiscutum primitivum in small numbers in surface sediments of Pariwar Formation and its common occurrence in coeval subsurface succession of Tanot Well-1 is the first record from the Cretaceous of Western India, which was located at ~30°S of the equator during mid-Cretaceous. S. primitivum is considered as cold-water, high-latitude taxa. Its presence in the Jaisalmer Basin suggests influx of cooler water currents from southern high latitudes during Albian time. Its co-existence with warm-water, wide-canal-bearing robust Tethyan nannoconids in the Jaisalmer assemblage suggests mixing of cold water masses with the warm waters in the western margin of the Indian subcontinent during Albian.