Late Campanian-Maastrichtian in Pondicherry Area (Cauvery Basin) Southern India: Bioevents and Palaeoenvironmental Inferences from Planktonic Foraminifera

The late Campanian/Maastrichtian succession exposed in the Pondicherry area provides one of the best exposed marine sections in the Cauvery basin and is examined for its foraminiferal contents. The biostratigraphic distribution of 72 species of planktonic foraminifera has been used to identify eleven planktonic zones and subzones and correlated to the global bioevents.The present biostratigraphic analysis has revealed four bioevents in the late Campanian-Maastrichtian sediments of the Pondicherry area. The first one was associated with the Radotruncana calcarata (CF10), which correlated to the late Campanian event (LCE); the second bioevent was associated with the Rugoglobigerina rotundata (CF7a) and the Rugoglobigerina scotti CF7b, which correlated to the (Campanian-Maastrichtian boundary event (CMBE); the third bioevent is associated with Globotruncana linneiana and Contusotruncana contusa, which correlated to middle Maastrichtian event (MME). The fourth bioevent associated with the Racemiguembelina fructicosa, which is correlated with the late Maastrichtian event (LME) associated with the Cretaceous/Paleogene boundary in the studied area.Three principal climate and faunal associations were identified in the present study in Cauvery basin; (1) worldwide cooling with minimal variation in the late Campanian-earliest Maastrichtian observed through extraordinary diversification for the Cretaceous mostly accomplished in the early Maastrichtian (Event-1, C31r), (2) warming and stable high diversity (Event-2, upper C31r to lower C30n), (3) return to global cooling and high-stress environments (Event-3, C30n)