SPATIAL AND TEMPORAL VARIATION OF THE SEDIMENTATION RATES IN OKINAWA TROUGH SINCE THE LATE PLEISTOCENE AND THEIR CONTROLLING FACTORS

By using the collected chronological data of 33 sediment cores from Okinawa Trough, the sedimentation rates (SR) in different chronological sections of these cores were calculated. The results show very large spatial-temporal variations of the sedimentation rates in the trough. Spatially, there is an increasing trend of the SR from the north to the south, and the SR is much larger in the western slope of the trough than that in the eastern slope. Temporally, the SR increased greatly from late Pleistocene to Holocene. Owing to the result that the sediment in the trough was mainly composed of the terrigenous detritus, we suggest that the variability of the SRs in different parts and different chronological sections in the Okinawa Trough just reflected the complexity of the sedimentation environment and material origins, and mainly resulted from the variation of the sedimentation processes and sediment budget in different sites and ages. Meanwhile, the paleoceanological changes, the shifts of the Kuroshio Currents since the last deglaciation in this area also played an important role in this variation of the SRs. However, the event sedimentation, such as the volcanic event, and turbidites can also take great effect on the sediment accumulation in Okinawa Trough, thus, the effect of event sedimentation could not be less-estimated.