CHARACTERISTICS OF Rb/Zr RATIO OF DLC70-3 CORE FROM SOUTH YELLOW SEA AND ITS ENVIRONMENTAL IMPLICATION SINCE LATE PLEISTOCENE

The DLC70-3 core from South Yellow Sea was scanried with XRF Core Scanner in 1 cm interval. It is found that the terrestrial elements Rb and Zr in the sediments showed an excellent pattern of lamination in the vertical direction.And the relative contents of Rb and Zr change significantly in different grain-size fractions.Rb is high in the fine grained sediments while Zr is opposite. Rb/Zr ratios can reflect the change in relative content of clay minerals to quartz and feldspar. It is supposed that the Rb/Zr ratio of the sediments of the DLC70-3 core is controlled by both the sea level and climate changes in the source area, of which the latter one dominates, the section of 26.50~38.00 m(MIS 4)consisting of coarse grain-size sediments is mainly influenced by the sea level change.The Rb/Zr ratio indicates that the chemical weathering was strong in the source area during MIS 5 and MIS 3, which corresponds well to the variation trend of the summer monsoon and chemical weathering indicators in the inland Loess Plateau area, especially during the early MIS 3(40~60 ka).