浑善达克沙地早全新世气候变化

Climate change in Otindag sandy land during the early Holocene

文中选取季风边缘区的浑善达克沙地为研究区,基于其南部的哈根淖尔沉积剖面,采用14C测年法建立年代序列,结合粒度参数和总有机碳含量的综合分析,探讨剖面沉积过程以及古湖泊水位变化,重建早全新世气候变化过程。结果表明,在10.8~8.5 Cal.ka BP间,气候总体上表现为由冷干转为暖湿的过程,湖面呈逐渐扩张趋势。代用指标指示其间气候振荡频繁,可能发生过5次冷干事件:约在10.6、10.0、9.8、9.5以及9.2 Cal.ka BP,湖泊短期收缩;在约8.8 Cal.ka BP还存在一次转暖过程,湖泊扩张。通过与周边地区沉积记录、北大西洋浮冰事件、格陵兰冰芯及东北哈尼泥炭的δ18O记录相比对,浑善达克地区气候变化与季风边缘区基本保持一致,也是对全球气候变化的区域响应。

Otindag sandy land locates in the monsoon marginal zone,it is greatly sensitive to climate change.Based on the sediment record of Hagen lake profile,we used14 C dating method to construct the chronosequence of lake sediments and discuss the paleolake level and the sedimentary process combined with the particle parameters analysis and the total organic carbon content to rebuild the climate change during the early Holocene. Results show that median particle size and average particle size turned small from down to up; the content of silt and the peakedness value both decreased correspondingly,which indicates dry-cold climate gradually turned to wet-warm climate during 10. 8 ～ 8. 5 Cal. ka BP with the frequent oscillations. There were mainly five dry-cold events： 10. 6,10. 0,,9. 5 and 9. 2 Cal. ka BP,respectively,indicating paleolake shrinking,climate mutation for a short duration and the sedimentary environment transition. There was a wet event occurring in 8. 8 Cal. ka BP with the large precipitation,which illustrates the lacustrine extension. Compared with the substitutive indexes of Ice-rafted debris event in North Atlantic,and the δ18 O records of Hani and Greenland Ice Sheet Project Two,research demonstrates that climate change in Otindag was better consistent with monsoon marginal climate change in addition to several climate sub-fluctuations as a result of the multiple solution analysis of the particle index and TOC,and it is a sensitively regional response to the global climate change.