Variability of the Tsushima warm current during the Pleistocene and its relationship with the evolution of the East Asian Monsoon; preliminary results from IODP Expedition 346 (Sites U1427 and U1428/29) based on benthic ostracod assemblages.

Author(s): Bassetti, Maria Angela; Alvarez Zarikian, C. A.; Toucanne, Samuel; Yasuhara, Moriaki; Holbourn, A. E.; Sagawa, Takuya; Tada, Ryuji; Murray, Rick W.
Author Affiliation(s): Primary:
University of Perpignan, CEFREM, Perpignan, France
Other:
Texas A&M University, United States
IFREMER, France
University of Hong Kong, China
University of Kiel, Germany
Kyushu University, Japan
University of Tokyo, Japan
Boston University, United States
Volume Title: AGU 2014 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2014; American Geophysical Union 2014 fall meeting, San Francisco, CA, Dec. 15-19, 2014. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: The semi-enclosed marginal sea bordered by the Eurasian continent, the Korean peninsula and the Japanese Islands has an average depth of 1350 m and is connected with other marginal seas in the region by shallow and narrow straits. At present, the Tsushima Warm Current (TWC), a branch of the Kuroshio Current, is the only warm current flowing into the marginal sea west of Japan. The TWC carries both subtropical water originating from the North Pacific and fresher runoff water derived from East China Sea continental shelf. The northerly flow of the TWC through the shallow Tsushima Straits is ultimately controlled by relative sea level variations over time. IODP Expedition 346 Sites U1427 and U1428/29 are ideally located to record changes in (i) the intensity of the influx of the TWC, and (ii) the intermediate ventilation of the marginal sea over the last million years. The Japan Sea Intermediate Water (JSIW) corresponds to a vertical salinity minimum, found below the TWC, between 200 and 400-500 m water depth. The JSIW shows a relatively high oxygen concentration, related to the deep water convection in winter and linked to fresh water supply during winter monsoon intervals. Based on recent observations, it is thought during glacial and interglacial conditions, and millennial scale climate cycles the intensity of deep and intermediate water currents varied but the mechanisms of such variations are not fully known. Microfossil faunal proxies can be used for tracking bottom environmental conditions related to variability of the bottom water circulation intensity. Here, we present preliminary results obtained using ostracods (benthic microcrustaceans) that are abundant in the sedimentary sequences recovered at Sites U1427 and U1428/29, and are known to react sensitively to changes in water masses physico-chemical parameters. In particular, the variability of the genus Krithe through time is correlated with the sortable silt (carbonate-free, 10-63 µm sediment size distribution) to infer current speed and bottom water ventilation.
Year of Publication: 2014
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 24 Surficial Geology, Quaternary Geology; Asia; Cenozoic; Currents; East China Sea; Expedition 346; Far East; IODP Site U1427; IODP Site U1428; IODP Site U1429; Integrated Ocean Drilling Program; Japan; Japan Sea; Kyushu; North Pacific; Northwest Pacific; Ocean currents; Pacific Ocean; Pleistocene; Quaternary; Tsushima; West Pacific; Yamato Basin
Coordinates: N355755 N355756 E1342636 E1342636
N314038 N314039 E1290200 E1290200
N313702 N313703 E1285951 E1285951
Record ID: 2015117209
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