Benthic Foraminifera and Clay Mineralogy Across the Cretaceous-Tertiary Boundary in Cauvery Basin, India

Two relatively uninterrupted sequences spanning the Cretaceous-Tertiary boundary (KTB) arc present at two sites, namely Ammapettai-A (AMT-A) in Thanjavur sub-basin and Anandathandavapuram-A (ATP-A) in Ariyalur- Pondicherry sub-basin in Southern India. A total of 28 benthic foraminiferal species were identified at the generic or specific level. The occurrence of Nuttallides truempyi, Gavelinella beccariiformis, Bulimina trinitatensis and agglutinated foraminifera across KTD suggests that the palcobathymetry was >500m, and that deep sea benthic foraminifera were not severely affected by the KTB event. However, changes in foraminiferal relative abundances and their morphotypes were noticed across KTB and were related to changes in supply of organic fluxes to the basin floor. The clay mineral assemblages across KTB at the two sites appear to be little different. The high abundance of kaolinite clay close to the KTB at site AMT-A, may be attributed to progradational or shifting of depositional pattern.