PLEISTOCENE PALEOCLIMATIC ZONATION IN NORTHERN INDIAN-OCEAN AS REVEALED FROM GLOBOROTALIA-MENARDII ABUNDANCE

The fluctuations in frequency of occurrence of Globorotalia menardii a commonly occurring planktonic foraminifera at DSDP Sites 219, 220 and 241 have been correlated with the Pleistocene paleoclimatic (Ericson) zonation. Abundance of Gr. menardii has been found to be high to mode rate during R, T, V, X and Z (all interglacial, interstadial and post- glacial) zones while it was remarkably low during S, U, W and Y (all g lacial) stages. Varying thicknesses of the above paleoclimatic zones a t these three sites are due to differences in sediment accumulation ra tes. A comparison of Gr, menardii and total planktonic foraminiferal a bundance at these sites show very good correspondence, the correlation coefficients of which are highly significant, indicating Ericson pale oclimatic zones can be precisely delineated with the help of total pla nktonic foraminifera also in tropical region.