| Budget Amount *help |
¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 1997: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1996: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Research Abstract |
1) Electron spin resonance (ESR) spectra of quartz grains of loess and eolian dust collected from Siberia, Korea, China, Japan, Formosa, New Zealand, Turkey and Austria were measured in order to identify the source area of eolian dust and to reconstruction prevail winds during MIS 2. Results are as follows ; Quaternary : <0.7, Tertiary : 2.0-2.8, Wesozoic or paleozoic quartz : 3.3-4.7, Precambrian quartz : 11.0-17.1 (unit : 2.51E+13vacancies).
2) Eolian dust in the northern Japan was supplied by NW winter monsoon. from Siberia and Mongolia where the Precambrian rocks are widely exposed. The central and southern Japan, eolian dust supplied from central Asia by summer westerlies. The southernmost islands of Japan supplied from Souh China and India where the Precambrian rocks are widely exposed by winter westerlies. Under the assumption that the values of ESR intensity signal of eolian quartz reflected those of the quartz at the source area of eolian dust, the source area and trajectory of eolian dust could be reconstructed.
3) Loess in Formosa was affeced the deposition of local eolian material. Loess of the North Island in New Zealand was also affected the deposition of volcanic tephra in large quantity. Loess of South Island was affected significantly the deposition of eolian dust carried from Precambrian rock areas in Australia by westerlies.
4) Abrupt changes in dust deposition were just before glacial terminations such as Dansgaard-Oechger cold events or Heinrich events. Eolian dust loading on snow field of the Tibetan Plateau and associated snow darking may have introduced strenghening of summer monsoon. Dust-induced changing of monsoon may have a role in triggering climate changes.
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