末次冰消期以来内蒙古东部气候变化——基于风成砂-古土壤序列的地球化学记录

通过对内蒙古东部现代东亚季风界线两侧的浑善达克沙地和呼伦贝尔沙地风成砂-古土壤剖面的光释光、~(14)C年代和沉积物主、微量元素地球化学的分析,重建内蒙古东部末次冰消期以来气候变迁过程。浑善达克沙地的浩来呼热剖面(hsh1-09)显示了末次冰消期以来3次暖湿气候期,分别对应末次冰消期、全新世大暖期、中世纪暖期。呼伦贝尔沙地的嵯岗剖面(CG-09)表现了全新世大暖期和中世纪暖期两次的暖湿气候期。这一过程是对东亚夏季风的响应,大致反映了内蒙古东部末次冰消期以来的东亚夏季风两次不同程度增强及大暖期结束的南退过程。通过对比前人研究结果,全新世中期东亚夏季风较强,在内蒙古东部大约距今4 ka开始减弱、南退;中世纪暖期夏季风强度较弱,持续时间短。

A study of paleoclimate changes in east Inner Mongolia since the Last deglaciation on the basis of aeolian sand-paleosoil series geochemical records

Abstract: Otindag sandy land and Hulun Buir sandy land belong to east Inner Mongolia and lie on the two sides of modern East Asian Monsoon (EAM) boundary. Based on optical stimulated luminescence (OSL) and 14C dating method combined with chemical elements analysis, regional paleoclimate was reconstructed. The results indicate that Otindag sandy land experienced three warm wet periods in the last deglaciation, Holocene optimum and Medieval warm period respectively. Whereas Hulun Buir sandy land only experienced the last two warm epochs. These periods were responses to the East Asian Summer Monsoon (EASM), roughly reflecting the EASM enhancement in two different degrees since the last deglaciation and the retreat process in the end of Holocene optimum. By contrast with previous studies, the EASM began to retreat at about 4 ka in east Inner Mongolia; the monsoon intensity was weaker in Medieval warm period, and the duration was short.