The Sea of Japan (JS) is a unique marginal sea in the western North Pacific that is characterized by four shallow straits. It can provide information about the paleoenvironment, for instance indicating variations in the East Asian Monsoon, Tsushima Warm Current, sea ice coverage, and Westerly Jet. Compared with other marginal seas in the western North Pacific, the JS is currently the only marginal sea without influx from large rivers. It is, therefore, of interest to determine the source of terrigenous sediments over time, particularly in the western JS, which has been less investigated in previous reports. In this study, a suite of multi-proxies including Sr and Nd isotopes and minor elements were measured for fine fractions (<63 μm) of core LV53-18-2 that were recovered from the western JS over the last 30 ka. Our results show that the sediments are rich in volcanic detritus and that the provenance of terrigenous sediments in the western JS is mainly derived from the arid region in northern China and coastal areas in the Far East. During the Last Glacial Maximum, the increased coverage of sea ice may have contributed to the accumulation of terrigenous debris. Meanwhile, the stronger East Asian Winter Monsoon and expansion of the Westerly Jet over northern China also carried more dust to the study area. However, the weakened atmospheric circulation and rise in sea level, induced by the ascending boreal insolation during the last deglaciation and early Holocene, remarkably reduced input of terrigenous debris, and the intense melting of sea ice delivered an amount of detritus from coastal areas to the research area. After 8 ka, the high stand sea level and opening of the Tatar Strait may have led to the development of the Liman Cold Current, which transports large quantities of volcanic materials to the study area continuously and produces more positive Eu anomalies, radiogenic εNd, and depleted ΣREE.
<p>The formation of intermediate and deep water plays a key role in regulating climate changes at a variety of time scales through the heat redistribution and carbon cycling. The Japan Sea has unique water-mass characteristics in the North Pacific with its own deep-water formation within the Sea itself called Japan Sea Proper Water (JSPW). Latitudinal ventilation changes in the Japan Sea were reconstructed using radiolarian assemblage from three sediment cores, extending from the southwestern, central to northwestern Japan Sea. Here, we present downcore faunal records spanning the last 25&#8239;ka as well as other existing ventilation records in the Japan Sea, and provide reliable evidence to evaluate the potential controlling mechanism that lead to onset and interruption of JSPW ventilation. Taking all together, we argue that radiolarian assemblage records have revealed a distinct basin-scale transition in deep-water conditions from anoxic to oxic during the deglaciation related to changing surface hydrography. However, it should be recognized that there is significant potential for bias in the timing of the ventilation changes among regions. Deep ventilation in the central Japan Sea has been in an interglacial mode during the B&#248;lling/Aller&#248;d presumably related to northward volume transport of the Tsushima Warm Current. Moreover, the decrease of JSPW Assemblage at the B/A in southwestern Japan Sea was attributed to higher export productivity, facilitating suboxic deepwater condition through enhanced consumption of oxygen, which was probably caused by coastal upwelling. In contrast, the weakening ventilation of the northwestern Japan Sea during the B/A and YD periods was probably caused by the blocking effect of the sea ice. Note: This study was supported by the National Natural Science Foundation of China (Grant No. 41420104005, U1606401) and National Program on Global Change and Air-Sea Interaction (GASI-GEOGE-04).</p>
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