NOAA/WDS Paleoclimatology - Northern Okinawa Trough Geochemical, Sedimentary and Oxygen Isotope Data during the last 24.3 ka

Geochemical and sedimentological analyses of core PC-1 recovered from the northern East China Sea (ECS) provide insights into variations in terrigenous input associated with sea-level and climate changes over the past 24.3 ka. Based on high-resolution multiproxy records, our results suggest that the competing processes of sea-level and monsoonally-driven precipitation determined terrigenous input to the northern ECS. Dominance of terrigenous material, along with relatively light G. ruber d18O, indicate that the Last Glacial Maximum (LGM) lowstand of sea-level have occurred during the period 21.5-19.6 ka, not suggesting an early slow rise but supporting the conventional LGM age of 21 ka. This LGM lowstand was terminated by the rapid sea-level rise of 19-ka MWP, which is well expressed by the nearly synchronous decreases in both terrigenous detritus and mean grain size from 19.6 to 18.9 ka. MWP-1A is clearly marked in our records by a sharp reduction in terrigenous input and pronounced maxima of G. ruber d18O at 15.3-14.8 ka, given the considerable age uncertainties of deglacial marine radiocarbon samples. A slightly increasing input of terrigenous matter is noted after 13.4 ka, potentially pointing to a sea-level fall following the Inter-Allerød Cooling Period (IACP), which was seldom reported previously. Although MWP-1B did not leave robust signatures in terrigenous input, it is explicitly captured by the heavy d18O of G. ruber and decline in mean grain size at 11.5-10.9 ka. MWP-1c probably occurred in a broad millennial interval with multiple peaks, which are robustly marked by the abrupt variations in terrigenous input and marine organic matter at 9.7-9.3 and 9.1 ka, respectively. During the late Holocene, the effect of continuously weakening monsoon precipitation overwhelmed that of stable sea-level resulting in a uniform increase in the proportion of marine-derived organic matter after 5.5 ka.