The Younger Dryas in the West Pacific marginal seas

摘要

The occurrence and nature of the Younger Dryas (YD) abrupt climatic event in the West Pacific marginal seas are discussed on the basis of 15 sediment cores. This event has been found in all these cores studied with a high-resolution stratigraphy and proved to be common to the West Pacific region. As shown by the isotopic and micropaleontologic analyses, the YD, dated by C-14 at about 11 000 to 10 000 a B.P., is a brief event of sea surface cooling in winter season following a fresh-water pulse about 12 000 a B.P. The "apparent regression" of the YD recorded in the Changjiang River delta and the Sea of Japan agrees with the interpretation that the YD is a period of slowed sea level rising between two phases of rapid rising. Both the winter surface water cooling and the increasing salinity in the YD imply a strengthening of the winter, but not summer monsoon circulation. This major climatic event in the marginal seas must have had profound impact on the adjacent continent.