科尔沁沙地黄土序列中正构烷烃组成特征反映的全新世气候时空变化研究

Climate system of Horqin Sandland, located at the tail-end area of the Asian monsoon influences, varies spatially and temporally when competition happens between summer monsoon and winner monsoon. The changes of the Asian monsoon system dominated the conditions of humidity and temperature which formed certain climate and ecosystem in the mostly region of east Asia and determined the development direction of human civilization in the past ten thousand years (Holocene). Based on analysis of multi-climatic proxies, which include n-alkane (biomarker) component characteristics and other regular climatic proxies, it will try to reconstruct climate change sequence in Horqin Sandland during Holocene and discuss an influence and function of climatic force for regional or global area in this research. High resolution loess samples from five loess profiles scattered evenly in Horqin Sandland will be determined for climatic proxies (n-alkane component characteristics, particle size, carbonate concentration, TOC, magnitic susceptibility, et al.) analysis. Comparing the climatic meanings of these proxies, certain characteristic parameters of n-alkane component will be screened out as the most effected indicator to reconstruct the history of vegetation type and climate changes in Horqin Sandland during Holocene combining with a reliable chronology. After these, a regular pattern of climatic elements’(such as temperature and moisture) distribution in spatical and temporal aspects during Holocene will be concluded via synthesizing all information acquired from this research, already reported researches and historical records from Horqin Sandland.

科尔沁沙地处于东亚季风尾闾区，其气候受东亚夏季风和冬季风竞争关系的影响，从而呈现出空间和时间上的差异。东亚季风系统在过去一万年（全新世）里的变化过程基本主导了东亚大部分地区的水热条件变化并形成了相应的气候和生物植被表现，甚至决定了人类文明的发展方向。本研究试图通过对以生物标志物正构烷烃组成特征为主的多种气候指标分析来建立科尔沁沙地全新世以来的气候环境变化序列，讨论区域和全球性的气候驱动因素的作用和影响。研究将在科尔沁沙地选择分布较均匀的五个黄土沉积剖面进行高分辨率的气候代用指标分析。通过正构烷烃组成特征指标与其他常规指标的气候指示信息对比来筛选出最能反映科尔沁沙地气候变化规律的正构烷烃特征参数，并结合常规气候代用指标和可靠年代框架来重建科尔沁沙地全新世植被和气候的演化历史。最后，将科尔沁沙地各点的重建结果与已有气候记录和历史资料综合分析来得出科尔沁沙地全新气候要素（温、湿）的时空分布规律。

科尔沁沙地处于东亚季风尾闾区，其气候受东亚夏季风和冬季风竞争关系的影响，从而呈现出空间和时间上的差异。本研究基于对以生物标志物正构烷烃组成特征为主的多种气候指标分析来建立科尔沁沙地全新世以来的气候环境变化序列，讨论区域和全球性的气候驱动因素的作用和影响。通过对科尔沁沙地南缘和中北部两个黄土沉积剖面高分辨率正构烷烃特征指标（CPI、木本/草本、ACLt）和常规指标（粒度、TOC）的结合，以及可靠C14年代序列框架，本研究重建了科尔沁沙地的全新世气候变化序列。研究结果表明科尔沁沙地的南部全新世气候具有典型东亚季风气候系统特征，在约7000 a BP到4400 a BP有全新世适宜期的气候阶段表现，而中北部腹地区域的全新世气候整个偏干和脆弱，仅在4400a BP至1500a BP段有较弱的气候相对适宜的时段出现，其可能受到西风带气候系统的遥相关作用影响。