Late Quaternary Sedimentation and Paleoceanography in the Southern Okinawa Trough: A Synthesis of ODP1202 Scientific Results

Ocean Drilling Program Site 1202 was designed to study the sedimentary regimes of the southern Okinawa Trough and the paleoceanographic evolution of the Kuroshio (Black Current) in the northwest Pacific. Towards this end, this article reviews the last results of recent studies of the southern Okinawa Trough and summarizes the principal findings made by shipboard scientists and shore-based post-cruise researchers. Despite its deep penetration to 410 m below sea floor, the drilled sequence records only a short history of the past 68 kyrs mainly due to the high sedimentation rates at this site. The lower section of the cores contains numerous turbidite layers with distinctive, phased sources of sediment supply. The upper 130 m is free of turbidite disturbance and provides a high-resolution record for magnetic, sedimentologic and paleoceanographic studies. Sea level change, consequently the locations of the shorelines, and the sill depth, determined the main features of sediments of the record. Between 30 and 11 ka, when the sea level was low, the sediments came from both East China continent and Taiwan. After 11 ka, Taiwan sources became dominant, meanwhile Kuroshio has entered the Trough. Sea surface temperature rose from ~23oC during the last glacial and deglaciation interval to ~26oC of Holocene. The monotonous Holocene sediment provides a high-resolution, high-quality record f magnetic intensity, which may serve as a good reference for regional and global correlation.