PROVENANCE OF SEDIMENTS IN THE NORTHERN OKINAWA TROUGH OVER THE LAST 24 KA: HIGH RESOLUTION RECORD FROM MAJOR ELEMENTS

Major elements were studied for reconstruction of sediment provenance and paleoenvironment over the last 24 kaBP with the samples collected from Core PC-1 in the northern Okinawa Trough. In addition to major elements, grain size of 402 samples and planktonic foraminifer δ¹⁸O of 344 samples have been analyzed that leads to an average resolution at centennial scale. The study offers a new high resolution material for reconstructing the history and main control factors of the sediment input in the northern Okinawa Trough over the last 24 ka. In according to the variation in major element compositions, the core could be divided into three distinct depositional units, separated by two volcanic layers at 7.3 and 12.7 cal kaBP respectively. Both provenance discriminating plot and R-mode factor analysis indicate that vertical changes in major elements are mainly contributed by the nearby terrestrial materials, whereas the contribution from hydrothermal activity, marine biologic deposition, and volcanism are minor. In particular, the contribution of nearby terrestrial materials show an obvious change trend and can be well correlated with the sea level fluctuation and the evolution of the Tsushima Warm Current. It seems that paleoclimate renders no significant impact on the change in terrigenous sediment provenance.