Stalagmite Stable Isotope Record And Climate Significance From Huangye Cave In Gansu Wudu

Gansu Wudu Huang Ye cave is in the transition zone of eastern Qinghai-Tibet Plateau and the Loess Plateau, near the impact of the Asian monsoon border and is the typical region in the impact of the Asian monsoon.To study the region's climate history of evolution will help us to understand and learn the impact of Asian monsoon's to the Northwest of China.The stalagmite (HY05-1) collected from the region, Gansu Province HuangYe cave provided the change history of Asian monsoon and the ecological evolution sequence of the region's vegetation that isotopic recorded of 856 years during AD842-AD1698.By studying stalagmite isotope significance in HuangYe cave of Gansu Province, the change of Huang Ye cave HY05-1 stalagmite oxygen isotopes is the effective proxy of intensity of the Asian monsoon. The region can be divided into the following three climate stages.First, AD842-978 weakening of the monsoon period is equivalent to DACP (cold dark period),δ¹⁸O andδ¹³C value are positive, monsoon precipitation is relative little and vegetation is characteristic with C4 plants for the large proportion. The climate stage is relative to the period in the history of my late Tang Dynasty and Five Dynasties period and the early Northern Song Dynasty.Second,AD978-1282 of monsoon dramatic increase and then gradual decrease period is equivalent to MWP (Medieval Warm Period ), showing thatδ¹⁸O andδ¹³C value are overall negative. Monsoon Force strengthened fast and then weakened gradually and vegetation is characteristic with C3 and C4 plants increasing in the proportion of plants. The climate stage is relative to the history of the Southern Song Dynasty and the late Northern Song period.Third, AD1282-1698 weakening of the monsoon period is equivalent to LIA (Little Ice Age), AD1282-1476 showing thatδ¹⁸O andδ¹³C values are overall positive.Monsoon strength reached the minimum in this session, the vegetation is characteristic with C3 and C4 plants decreasing in the proportion of plants. The climate stage is relative to the history of late Yuan Dynasty and early Ming Dynasty. AD1476-1698 the period of monsoon increase with volatility is relative to the late Ming Dynasty and early Qing Dynasty. Showing thatδ¹⁸O andδ¹³C are overall negative with Significant fluctuations. Monsoon strengthened wholly and the vegetation is also characteristic with C3 plants increasing in the proportion of plants by large. But the stage has sharp fluctuation and climate is very unstable.Compared HY05-1 stalagmite isotope records with cosmogenic nuclides, we found that Solar activity not only in the strength of the centennial-scale impact on the Asian monsoon strength, but also in 10 years scale ,solar activity is the important factors controlling Asia monsoon changes. Compared HY05-1 stalagmite oxygen isotopes with the reconstruction of the Scotland stalagmite record rainfall, Note the intensity of the Asian monsoon and the NAO index close.