| Budget Amount *help |
¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1991: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1990: ¥1,000,000 (Direct Cost: ¥1,000,000)
|
|---|
| Research Abstract |
Long range, tropospheric eolian dust transported from the Asian continents has been deposited on the land surfaces in Japan and Korea and on the sea floor of the Sea of Japan and the North Pacific Ocean since the late Pleistocene. Nonallophanic andosols, red yellow soils developed on limestones, basalts, and others diverse parent materials, and paleosols buried in paleodunes in the area along the coast of Japan Sea, were strongly influenced by the eolian dust derived from the Asian Continents.
The eolian dust was characterized by a predominance of soil particles 0.7 to 30 mu m in diameter. The median particle diameters of wadi sediment in the Takla Makan ranged from 20 to 100 mu m. The median particle diameters of loess in China, loess derived soils, eolian dust, and pelagic sediments decrease steadily from the eastern part of China through Japan and Korea(3-30mum)to Hawaii and the north Pacific Ocean(0.7-8 mum). Their dominant minerals were 2 : 1 and 2 : 1 : 1 layer silicates, kaolinite, quartz, and feldspar, and were characterized by high K_20/SiO_2 and SiO_2/Al_2 0_3 molar ratios. Oxygen isotope compositions of fine grained quartz from soils and eolian dust deposits in Japan, Korea and the Japan Sea pelagic sediments ranged from 14 to 17%% indicating that it is of the Asian continental origin. The recent flux of Asian eolian dust is about 4 to 7 mm/1000 yrs. compared to about 14 to 23 mm/1000 yrs. in the late Pleistocene glacial periods.
Israel eolian dust from the Saharan desert accumulated at an average rate of 0.5 to 1 mm/year in the late Quaernary.
|
