CENOMANIAN PLANKTIC FORAMINIFERAL BIOSTRATIGRAPHY OF SOUTHERN INDIA AND THEIR CORRELATION

Two hundred and forty eight sediment samples were collected systematically from the Karai Shale, exposed between Karai-Kulakkalnattam Villages, Perambalur District, Tamil Nadu, India for the study of Cenomanian planktic foraminiferal biostratigraphy and their correlation. Seventeen species of planktic foraminifera and seventy one species of benthic foraminifera were identified in the present study. The planktic foraminifers identified are as follows: Clavihedbergella simplex, Globigerinelloides bentonensis, Globigerinelloides caseyi, Globigerinelloides ultramicra, Hedbergella ambilis, Hedbergella bornholmensis, Hedbergella delrioensis, Hedbergella planispira, Hedbergella portsdownensis, Praeglobotruncana delrioensis, Praeglobotruncana stephani, Rotalipora cushmani, Thalmanninella appenninica, Thalmanninella balernaensis, Thalmanninella evoluta, Thalmanninella greenhornensis and Thalmanninella reicheli. The benthic foraminifers identified are as follows: Ammodiscus cretaceus, Ammodiscus planus, Anomalinoides indica, Astacolus jarvisi, Citharina sp., Dorothia filiformis, Dentalina basiplanata, Dentalina cylindroides, Dentalina marginuloides, Dentalina strangulata, Dentalina trujilloi, Eouvigerina uttatturensis, Frondicularia filocincta, Frondicularia goldfussi, Frondicularia mucronata, Gaudryina tailleuri, Gavelinella baltica, Gavelinella cenomanica, Gavelinella intermedia, Gavelinella simionescui, Gavelinella rudis, Globulina lacrima, Globulina prisca, Glomospira charoides, Glomospirella gaultina, Gyroidinoides depressa, Gyroidinoides globosa, Haplophragmoides kirki, Lagena hispida, Lenticulina alexanderi, Lenticulina circumcidanea, Lenticulina gaultina, Lenticulina grata, Lenticulina macrodisca, Lenticulina navarroensis, Lenticulina nuda, Lenticulina ovalis, Lenticulina planiuscula, Lenticulina polygona, Lenticulina rotulata, Lenticulina saxocretacea, Lenticulina secans, Lenticulina stephensoni, Lingulogavelinella albiensis, Lingulogavelinella globosa, Marginulina glabra, Marginulina hamuloides, Marginulina hamulus, Nodosaria affinis, Nodosaria distans, Nodosaria larva, Nodosaria obscura, Nodosaria orthopleura, Oolina apiculata, Oolina simplex, Pleurostomella cullygoodiensis, Pleurostomella nitida, Pleurostomella obtusa, Pseudonodosaria cylindracea, Pseudonodosaria manifesta, Quadrimorphina allomorphinoides, Quadrimorphina camerata, Quinqueloculina antiqua angusta, Ramulina aculeata, Ramulina globulifera, Saracenaria triangularis, Tristix excavata, Tristix tricarinatum acutangulum, Vaginulina kochii, Vaginulina plummerae and Vaginulina recta. In the present study four planktic foraminiferal bio-zones were identified from Early Cenomanian to Late Cenomanian. The bases of these zones are defined based on the first appearance of a new taxon. The zones in the ascending order are as follows: Thalmanninella appenninica Interval Zone, Thalmanninella greenhornensis Total Range Zone, Thalmanninella reicheli Total Range Zone and Rotalipora cushmani Total Range Zone. These zones are correlated with the bio-zones reported from Northern California, North Atlantic, Morocco, Tunisia, Egypt, Northern Cyrenica in Libiya, NE Spain, South Eastern Spain, Umbria, Anglo-Paris basin, Switzerland, Poland, England, SE-Devon, South-western Crimea, Northeast of Kerguelen Ridge and Western Pacific Ocean.