DO BENTHIC FORAMINIFER RECORDS REPRESENT A PRODUCTIVITY INDEX IN OXYGEN MINIMUM ZONE AREAS - AN EVALUATION FROM THE OMAN MARGIN, ARABIAN-SEA

Benthic foraminifer accumulation rates (BFAR) and benthic to planktic foraminifer ratios (B/P) have been suggested to represent an index of paleoproductivity in the world oceans. It is shown here, however, that BFAR and B/P do not record the surface-water productivity signal in t he intense upwelling and oxygen minimum zone (OMZ) along the Oman Marg in. Greater BFAR and B/P values are noticed during the last glacial pe riod, when the monsoon and upwelling strength were weaker and the surf ace-water productivity was reduced. This is in contrast to the suggest ion that BFAR and B/P values are an indication of enhanced productivit y. On the other hand, BFAR and B/P values were lower during the Holoce ne as a consequence of intensified monsoon and upwelling and resulting enhanced productivity in the Arabian Sea. This appears to suggest tha t BFAR and B/P do not reflect the productivity variations in the OMZ o f the Arabian Sea. We speculate that dissolved oxygen concentrations m ight instead be controlling the benthic foraminifer abundance.