青藏高原东缘都江堰湖相沉积MIS3a阶段的快速气候变化记录

深海氧同位素第3阶段晚期(MIS3a)是青藏高原较为特殊的暖湿时期, 为了解这一时期高原东缘的气候变化细节, 利用AMS14C定年和粒度、总有机碳、正构烷烃等环境代用指标提取了四川都江堰湖相沉积剖面的相应记录.经过校正后的日历年龄显示此剖面沉积于43.6~34.6 kaBP期间, 记录了千年尺度的D-O旋回事件, 其分布时段分别为: DO11(43.6~41.8 kaBP), DO10(41.8~39.2 kaBP), DO9(39.2~37.7 kaBP), DO8(37.7~35.5 kaBP), DO7(35.5 kaBP~未见顶).该剖面总有机碳曲线与南京葫芦洞石笋和格陵兰冰心(GRIP)氧同位素曲线的对比表明, 该区域气候记录对全球高纬地区的冰量变化和亚洲季风演化具有响应; 而中纬度太阳辐射岁差对该区域气候波动的控制作用较强导致了细节上存在差异. 

Rapid Paleoclimate Changes during MIS3a Reflected by Lacustrine Deposits of Dujiangyan in the Eastern Margin of Qinghai-Tibet Plateau

The later phase of marine isotope stage 3 (i.e. MIS3a) on Qinghai-Tibet plateau was characterized by its special warm-humid climate. The constructed AMS14C calendar age-depth model, the component of n-alkanes, together with the grain size and total organic carbon (TOC) of lacustrine sediments in Dujiangyan S1 Section are used to elucidate the paleoclimate changes. The results indicate that rapid fluctuation on millennial scale was the main characteristic in the eastern margin of Qinghai-Tibet plateau during 43.6—34.6 kaBP. The Dansgaard-Oeschger events 11—7 can be reflected by these proxies, especially TOC. Comparison between TOC curve and oxygen isotope record from Hulu Cave and Greenland GRIP indicates that paleoclimate records in Dujiangyan respond to ice volume change in the high-latitude area and Asia monsoon oscillation. But the difference was shown because the influence of insolation values precession was strong in this area.