Su Xin and Wei, Kuo-Yen (2005): Calcareous nannofossils and variation of the Kuroshio Current in the Okinawa Trough during the last 14,000 years

Leg/Site/Hole:
ODP 195
ODP 195 1202
Identifier:
2005-062438
georefid

Creator:
Su Xin
China University of Geosciences, Center of Marine Geology, Beijing, China
author

Wei, Kuo-Yen
National Taiwan Normal University, Taiwan
author

Identification:
Calcareous nannofossils and variation of the Kuroshio Current in the Okinawa Trough during the last 14,000 years
2005
In: Wei, Kuo-Yen (editor), Mii, Horng-Sheng (editor), Huang, Chi-Yue (editor), Okinawa Trough; sedimentary processes and paleoenvironment
Institute of Earth Sciences Academia Sinica, Taipei, Taiwan
16
1
95-111
A quantitative census study on calcareous nannofossils from sediments of Site 1202 recovered by ODP Leg 195 and surface sediments from the East China Sea was carried out to obtain a high-resolution nannofossil record of the change of the Kuroshio Current during the late Quaternary. Two nannofossil ratio indices were designed and employed in this study: (1) ratio of Florisphaera profunda against F. profunda, Emiliania huxleyi and Gephyrocapsa oceanica (F-EG ratio) as a nannofossil proxy of the Kuroshio Current, (2) ratio of G. oceanica against F. profunda and E. huxleyi and G. oceanica (G-FE ratio) as a proxy of near-coast environment. Results from the 14 surface nannofossil samples demonstrate that the F-EG ratio is >15% in the assemblage lying directly under the main route of the Kuroshio Current, whereas it is very low (<10%) in sediments off the current. High ratios G-FE (>30%) were seen from all samples on the East China Sea continental shelf or from near-coast cores. Down hole nannofossil record from the top 60 mbsf sediment interval at ODP Hole 1202B reflects the change of the Kuroshio Current in the last glacial and postglacial period since 14 ka. Extreme low F-EG ratio together with very high G-FE ratio at Hole 1202B during the time of the latest Pleistocene and the earliest Holocene suggest the absence of the Kuroshio Current in the area studied. The event of intrusion of the Kuroshio Current was clearly recorded by a dramatically increase of F-EG ratio and notably a reduction in the G-FE ratio around 9 ka. Furthermore, based on the variation of the F-EG ratio and delta (super 18) O of planktonic foraminifera Neogloboquadrina dutertrei, variation of the Kuroshio Current in the Holocene shows three long-term cycles (with a periodicity of approximately 3000 yr).
English
Serial
Coverage:Geographic coordinates:
North:24.4900
West:122.3000East: 122.3100
South:24.4800

Quaternary geology; algae; assemblages; biostratigraphy; Cenozoic; glaciation; Holocene; Kuroshio; Leg 195; marine sediments; microfossils; nannofossils; North Pacific; Northwest Pacific; Ocean Drilling Program; ODP Site 1202; Okinawa Trough; Pacific Ocean; paleo-oceanography; paleoclimatology; paleoecology; Plantae; Pleistocene; quantitative analysis; Quaternary; sediments; upper Pleistocene; West Pacific;

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