祁连山南坡木里地区晚更新世晚期的气候变迁

通过对祁连山南坡木里地区晚更新世地层剖面AMS¹⁴C年代的测定,以及对沉积物粒度、磁化率及SiO₂、Al₂O₃、Fe₂O₃等氧化物含量的研究,重建了研究区晚更新世晚期44.8～35ka B.P.的气候变迁。木里地区晚更新世晚期44.8～35ka B.P.的气候可以分为3个阶段:(1)44.8～40.5ka B.P.,气候温暖湿润,41.9ka B.P.出现的暖事件与D-O振荡中的IS12对应;(2)40.5～35.5ka B.P.,气候波动频繁且在波动中变冷,该阶段成功捕捉到3次D-O振荡中的暖事件和1次Heinrich冷事件,3次暖事件与D-O振荡中的IS9、IS10、IS11对应,时间分别为35.8ka B.P.、37.5ka B.P.、39.7ka B.P.,冷事件与D-O振荡中的H3对应,时间为35.5ka B.P.;(3)35.5～35ka B.P.,气候波动大,具变暖趋势。整个阶段的气候波动与深海氧同位素第3阶段后期气候变化特征较吻合,亦揭示了全球变化信号在研究区的响应特征。

Climatic change during the late stage of Late Pleistocene at Muli area in south slope of Qilian Mountains

Based on the precise measurement of AMS¹⁴C ages in Late Pleistocene stratigraphic section at Muli area in the south slope of Qilian Mountains,and combined with the study of sedimentary grain size,magnetic susceptibility, and oxide(SiO₂,Al₂O₃ and Fe₂O₃)content,we reconstructed the climatic change of the study area during 44.8-35ka B.P. with 3 stages:(1)During 44.8-40.5ka B.P.,all the proxies show that the regional environment is warm and humid. The warm event around 41.9ka B.P. corresponds to IS12 in Dansgaard-Oeschger events;(2)During 40.5-35.5ka B.P.,the climate fluctuated frequently and tended to be cold. The three warm events of IS9-IS11, i.e., 35.8ka B.P.,37.5ka B.P.,and 39.7ka B.P.,respectively,and the H3 cold event of 35.5ka B.P.,were found during this period;(3)During 35.5-35ka B.P.,the climate fluctuated strongly and tended to get warm. These features of climatic fluctuation fit well with those of the late stage of MIS3. It indicates that the climate changes could spread globally but the precipitation situation varies in different areas.