Pulleniatina obliquiloculata as a paleoceanographic indicator in the southern Okinawa trough during the last 20,000 years

Abstract

Pulleniatina obliquiloculata, a tropical species of planktonic foraminifera, is indicative of the Kuroshio current and sensitive to winter sea surface temperature for the late Quaternary in the Okinawa Trough. Its relative abundance fluctuations are significant and correlatable between three gravity cores (cores 255, 170, 253) raised from the southern Okinawa Trough. Four major changes in its abundances with paleoceanographic significance have been recognized during the last 20,000 years: an abrupt increase at the Pleistocene/Holocene boundary, a short-term decrease indicative of a ‘Younger Dryas’-type climate reversal at about 11.4-9.6 ka B.P., the P. obliquiloculata maximum zone (around 7-6 ka B.P.) corresponding to the mid-Holocene climate optimum and the P. obliquiloculata minimum zone (around 4-2 ka B.P.) correlated probably to the Neoglacial cooling. The widespread occurrence of these events in the western Pacific and the correlated variations of its abundance between sea areas suggest that P. obliquiloculata is well promising as a paleoceanographic and climatic monitor for high-resolution reconstruction and sea-land correlation.