Holocene variability of the Kuroshio Current in the Okinawa Trough, northwestern Pacific Ocean

Cores 255 and B-3GC from the southern and northern Okinawa Trough, respectively, were studied for determining the variability of the Kuroshio Current on centennial scales during the Holocene based on detailed AMS 14C dates, stable isotope, and planktonic foraminiferal distribution. The main flow of the Kuroshio Current was inferred to re-enter the Okinawa Trough at ∼7.3 calendar (cal.) kyr BP, leading to abrupt changes in sedimentation rate, remarkably increased abundance of the Kuroshio Current indicator Pulleniatina obliquiloculata, increased sea surface temperature (SST) and depth of thermocline (DOT). During ∼4.6–2.7 cal. kyr BP, the abundance of P. obliquiloculata sharply decreased, corresponding to a decreases in SST and DOT, implying that the influence of the Kuroshio Current weakened at that time, possibly as a result of the intensified winter monsoon. Significantly, the Kuroshio Current proxies (e.g. the difference in SST between the southern and northern Okinawa Trough) display periodicities of ∼1500 yr and ∼700–800 yr (ascribed to the second harmonic of the 1500 yr cycle in oceanic thermohaline circulation) during the Holocene. The Holocene events (at ∼0.6, 1.7, 3.3, 4.6, 5.9, 8.1, 9.4 cal. kyr BP) in the Okinawa Trough appear to be the most recent manifestation of the millennial scale climate cycle, recorded in the North Atlantic, Arabian Sea marine sediment cores and Greenland ice cores, suggesting global climatic tele-connections.