Paleoenvironmental and paleoclimatic changes in the Japan Sea since the last glaciation

2020 ◽  
Author(s):  
Xuefa Shi ◽  
Jianjun Zou ◽  
Sergey Gorbarenko
Keyword(s):  
Sea Ice ◽  
Sea Level ◽  
East Asian ◽  
Japan Sea ◽  
Sediment Provenance ◽  
Last Deglaciation ◽  
Central Japan ◽  
Warm Current ◽  
Ice Coverage ◽  
The Japan Sea

<p>The Japan Sea, one of the marginal seas of the North Pacific, communicates with adjacent seas through four shallow straits (<130 m) and the present environment in the Japan Sea is mainly forced by the Tsushima Warm Current (TWC), East Asia Monsoon (EAM) and seasonal sea ice. During the Quaternary, the pronounced effects of glacial eustatic sea level on the hydrography, ocean biogeochemistry and sediment depositions in the Japan Sea over glacial-interglacial cycles. However, the spatial heterogeneity of these forcings exerting on environment of the Japan Sea may results in contrasting response. On the basis of a suite of sediment cores collected during the China-Russia joint expedition in 2010, we investigate the sedimentary processes and paleoenvironment changes in the Japan Sea. We found enhanced extent of seasonal sea-ice coverage in the western Japan Sea, which is synchronous with the intensification of East Asian Winter Monsoon (EAWM) from 15ka to 8ka. During the early last deglaciation (17ka-15ka), perennial sea ice cover at investigated site occurs and thus inhibits the deepwater formation in the Japan Sea. Since 8 ka, increased deep ventilation and dampened sea ice coverage are closely related to enhanced EAWM and invasion of high-salinity TWC into the Japan Sea. In the southern Japan Sea, the sediment provenance is mainly derived from the Yangtze and old yellow rivers, while the terrigenous matter was mainly sourced from the Yangtze River after 7 ka, on the basis of elemental and radiogenic isotopic data (Sr and Nd) of fine-sized (<63 μm) sediments. Abrupt shifts in sediment provenance occurred at ~18 ka and ~7 ka and these time periods are synchronous with changes in surface hydrography and deep ventilation in the Ulleung Basin. In the central Japan Sea, eolian dust sourced from central Asia and Chinese Loess Plateau by westerly was delivered to the central Japan Sea. In addition, deep ventilation in the southern and central Japan Sea evidenced by redox-sensitive elements and ventilation-like radiolarian species suggest intensified ventilation since 8ka and during cold spells of the last deglaciation, which is closely related to the invasion of the Tsushima Warm Current into the Japan Sea. Our data suggest that sea level is a first-order factor in controlling the environment and sediment deposition in the Japan Sea at orbital timescales, while the East Asian Monsoon and Kuroshio Current play a secondary role. Note: This study was supported by the National Natural Science Foundation of China (Grants No. 41420104005, U1606401) and National Program on Global Change and Air-Sea Interaction (GASI-GEOGE-03 &-04).<span> </span></p>

scholarly journals Pliocene ostracods (Crustacea) from the Togakushi area, central Japan; palaeobiogeography of trans-Arctic taxa and Japan Sea endemic species

2008 ◽  
Vol 27 (2) ◽  
pp. 161-175 ◽  
Author(s):  
Hirokazu Ozawa ◽  
Hideaki Nagamori ◽  
Tomotaka Tanabe
Keyword(s):  
High Latitude ◽  
Endemic Species ◽  
Japan Sea ◽  
Kuroshio Current ◽  
The Arctic ◽  
Northwestern Pacific ◽  
Arctic Seas ◽  
Central Japan ◽  
The Japan Sea ◽  
Northern Atlantic

Abstract. Pliocene strata (4–3 Ma) in the Togakushi area, central Japan, yield significant ostracods, which allow investigation of the origins of high-latitude (Arctic–Atlantic) taxa and the Japan Sea endemic species, together with their post-Miocene history of extinction-speciation and migration. Three types of extinct species are found here: (1) cryophilic species in common with, or closely related to, species in Plio-Pleistocene assemblages described from the Japan Sea; (2) species closely related to, or comparable with, species that characterize Miocene Japan; and (3) species endemic to the Pliocene Japan Sea. Type (1) contains species closely related to high-latitude species known from the Arctic and northern Atlantic Oceans. Their presence suggests migration from the northwestern Pacific to the northern Atlantic through the Arctic seas since the Late Pliocene after the opening of the Bering Strait. Both Types (2) and (3) contain genera originating in the south, which show high specific diversity in regions affected by the modern warm Kuroshio Current. Ancestral ostracods of Types (2) and (3) invaded the Japan Sea from the Pacific from the Middle Miocene, and diversified to produce closely related species in the semi land-locked Japan Sea until the Early Pliocene. Two new species Aurila togakushiensis sp. nov. and Aurila shigaramiensis sp. nov. are described.

scholarly journals Unusually high sea level at the south coast of Japan in September 2011 induced by the Kuroshio

2020 ◽  
Author(s):  
Norihisa Usui ◽  
Koji Ogawa ◽  
Kei Sakamoto ◽  
Hiroyuki Tsujino ◽  
Goro Yamanaka ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Tide Gauge ◽  
Phase Speed ◽  
Japan Sea ◽  
South Coast ◽  
The South ◽  
Characteristic Analysis ◽  
The Japan Sea ◽  
The Kuroshio

Abstract Using a coastal assimilation model, generation mechanism of unusually high sea level (UHSL) at the south coast of Japan in September 2011 is investigated. Both model results and tide gauge observations indicate that sea level rise associated with the UHSL event occurred twice in the middle and end of September. The first one, which is localized around the eastern part of the Seto Inland Sea, is caused by a cyclonic circulation in the Kii Channel formed as a result of northward migration of the Kuroshio axis toward Cape Shionomisaki. The second sea level rise, which is the main contributor to this UHSL event, is observed in wide areas not only at the south coast of Japan, but also at the coast of the Japan Sea. It is brought about by a coastal trapped wave (CTW) induced as a result of a fluctuation of the Kuroshio path to the south of the Boso Peninsula. The CTW with positive SSH anomalies propagates westward along the south coast of Japan, and then goes into the coast of the Japan Sea. Sensitivity experiments and a modal characteristic analysis indicate that the CTW is mainly characterized by the first mode baroclinic Kelvin wave. The phase speed for the first mode is calculated at 2.96 m s$$^{-1}$$ - 1 , which compares well with that estimated by tide gauge observations.

scholarly journals Geochemical and Isotopic Evidence for Provenance of the Western Sea of Japan Over the Last 30000 Years

2021 ◽  
Vol 9 ◽  
Author(s):  
Ruxi Dou ◽  
Jianjun Zou ◽  
Xuefa Shi ◽  
Aimei Zhu ◽  
Zhi Dong ◽  
...  
Keyword(s):  
Sea Ice ◽  
Sea Level ◽  
Sea Of Japan ◽  
North Pacific ◽  
Western North Pacific ◽  
East Asian ◽  
Northern China ◽  
Coastal Areas ◽  
Westerly Jet ◽  
Marginal Sea

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.

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