Age of the MGS5 segment of the Milanggouwan stratigraphical section and evolution of the desert environment on a kiloyear scale during the Last Interglacial in China's Salawusu River Valley: Evidence from Rb and Sr contents and ratios

摘要

The MGS5 segment of the Milanggouwan stratigraphical section in China's Salawusu River Valley records 8.5 sedimentary cycles consisting of dune sands alternating with fluviolacustrine facies or/and paleosols. Based on a comprehensive analysis of the distribution of Rb and Sr within the segment and paleoecological evidence (fossils), it appears that the observed sedimentation cycles mainly resulted from fluctuations between dry-cold and warm-humid climates, which indicates that the MGS5 segment experienced at least eight cold-dry and nine warm-humid climatic fluctuations. Of these, 12 cold-warm climate fluctuations correspond to DO20-DO25 and stadia 21-26 recorded by the NGRIP ice cores. Another five cold-warm climatic fluctuations that occurred during MGSSe correspond to five substages (5el-5e5) recorded by the GRIP ice cores from Greenland. This kind of high-frequency climatic fluctuation on a kilo-year scale was mainly subject to variations in the strength of the East Asian winter and summer monsoons.