Oxygen Isotopic Composition of Albian-Turonian Foraminifera from Cauvery Basin, India: Evidence of Warm Sea-Surface Temperature

The clays of Karai Formation (Uttatur Group) contain well-preserved planktonic and benthic foraminifera of Albian-Turonian age. The pristine tests of planktonic and benthic foraminifera were analyzed for their oxygen isotopic compositions. The δ¹⁸0 values of planktonic foraminifera, comprising Whiteinella archaeocretacea, Marginotruncana sp., Rotalipora reicheli, Praeglobotruacana stephani and Globigerinelloides sp. indicate the maximum near-surface temperatures of 29°C. The bottom water temperature, estimated on benthic foraminifera1 species Gyroidinoides sp., Quadrimorphina sp., Gavelinella sp., Lenticulina sp. and Pleurustomella sp., is about 2. This is in agreement with the palaeoclimatic conditions inferred on fossil assemblages.