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[D-1.3.2 Studies to Estimate Long-Term Change of Element Cycles in Ocean Based on Microfossils and Other Sediment Components]

[Contact Person]

Akira Nishimura
Section Director, Marine Mineral Resources Section
Marine Geology Department
Geological Survey of Japan
1-1-3 Higashi, Tsukuba, Ibaraki 305 Japan
Phone +81-298-54-3594, Fax +81-298-54-3589
E-mail akiran@gsj.go.jp

[Total Budget for FY1993-1995]

25,682,000 Yen (FY1995 8,123,000 Yen)

[Abstract]

　Southern oceans around Antarctica have been focused as one of the most important areas which control global environmental change through ocean circulation, because Antarctic water is very nutritious and behaves as the source of deep ocean water. Sediment core sequences taken around Antarctica are expected to include a plenty of information of paleoceanographic change.
In this work, we tried to establish quantitative reconstruction of environmental change of the Antarctic seas including surface productivity, deep water circulation, and glacier development. We analyzed cores from the Ross Sea and adjacent regions. Sedimentological analyses of cores in the surface sediments of the Ross Sea revealed two lithologic units, upper pelagic unit of diatomaceous ooze and clay and lower semi-consolidated sandy silt. The lower lithologic unit suggests that the highly ice-sheet influenced sedimentation existed in glacier time and/or the ice sheet retreating in the Ross Sea. In the outer area of the Ross Sea, there are found contourites with highly laminated parts formed by bottom currents probably during glacial time. The sedimentary environment in the Late Quaternary is reconstructed based on the core data.

[Key Words]

Antarctic Sea, Marine Sediment, Microfossils, Flux, Productivity