Cretaceous (Albian-Turonian) calcareous nannofossil biostratigraphy of the onshore Cauvery Basin, southeastern India

A suite of outcrop samples from the Cauvery Basin belonging to mudrock-claystone dominated Karai Formation were analysed for nannofossil biostratigraphy in two newly measured sections at and Garudamangalam. The age Section is interpreted as early Albian Turonian, whereas Garudamangalam late Cenomanian. ‘BC’ zones Bown et al. (1998) are applicable both sections, Cenomanian Turonian ‘UC’ Burnett (1998), only partially applicable, due some problematic primary secondary markers. Albian-Cenomanian boundary appears be continuous approximated using FO lower ammonites M. mantelli Zone. Cenomanian-Turonian interval incomplete with a hiatus ~0.66 myr, indicated by absence upper Nannofossil Zone UC5. nannoplankton assemblages composed broadly cosmopolitan taxa, despite relatively high-latitude setting SE India during (~45°S), which reflected common occurrence biogeographically bipolar taxa such Repagulum parvidentatum Seribiscutum primitivum. palaeobiogeographic affinity nannoplankton, however, does not bear distinct Austral stamp, typical Sollasites falklandensis Zeugrhabdotus kerguelenensis very rare studied sections. appearance Crucibiscutum hayi Albian, Gartnerago segmentatum suggests that these species may have originated southern high latitudes before migrating northern Boreal regions. Four new calcareous species, Calculites karaiensis, Loxolithus bicyclus, Manivitella fibrosa Tranolithus simplex described.