PLANKTONIC PERCENTAGE OF FORAMINIFERAL FAUNA IN SURFACE SEDIMENTS OF THE ARABIAN SEA (INDIAN-OCEAN) AND A REGIONAL MODEL FOR PALEODEPTH DETERMINATION

The percentage of planktonic specimens in foraminiferal assemblages were determined in 126 surface sediment samples (depth range 13 to 1050 m) from the Arabian Sea along the western continental margin of India. The results obtained are in agreement with previous studies in other areas that planktonic percentage increases with depth. The resultant pattern is compared with results from the Atlantic margin of the northeastern United States, Gulf of Mexico, Timor Sea and Red Sea. Comparisons reveal that in spite of diversity between various areas, the over-all pattern indicate a positive correlation between planktonic percentage and depth. Based on the above relationship, a regional model has been constructed for the western continental margin of India in the Arabian Sea region to determine paleodepth from the planktonic percentage of fossil foraminiferal fauna. Regional differences in salinity patterns could be one of the main reasons for deviation of the regional model for the Arabian Sea with other regional models from Pacific and Atlantic regions and also with the Global model.