中文摘要：

摘要选择位于科尔沁沙地东北缘的六户屯剖面为研究对象，利用7个常规^14C年龄建立了风沙沉积的时间序列，通过对风沙沉积物粒度、CaCO3含量、有机质含量和环境磁学指标的系统分析，重建了科尔沁地区4300～1000cal．aB．P．的气候演化历史。结果显示，4300-3800cal．aB．P．为全新世大暖期末期，是研究区气候最暖湿的时期，且暖湿程度有不断降低的趋势；3800—1700cal．aB．P．为冷干气候期，其中3000cal．aB．P．为气候演变的节点，前期气候由暖湿逐步向冷干过渡，后期冬季风持续强盛，夏季风则逐渐恢复；1700—1000cal．aB．P．为亚暖湿气候期，气候条件相对暖湿，但不及大暖期时期。此外，环境磁学研究发现，磁粒度参数）CARM／X1和ZARm／SIRM可以作为气候代用指标，而常用的磁化率参数在本研究中指示意义不明确。由于原生碎屑磁性矿物已经达到稳定单畴（SSD）粒级，XARM/XH和HARM／SIRM与成壤作用表现为反相关。

英文摘要：

The Horqin sandy land（42°40＇ - 45°15＇N; 118°30＇ - 124°30＇E） in the western part of Northeast China is located in the present margin of East Asian monsoon zone, and its landscape is sensitive to the climate change. It lies in the transition zoon between the Inner Mongolian Plateau and the Manchurian Plain,with a total area of about 50000km2. This.region is characterized by continental monsoon climate,with a mean annual temperature of 3 -7℃. The mean annual precipitation ranges from ca. 500ram in the southeast to ca. 350mm in the northwest, with about 70% of the rainfall in summer. Stabilized and semi-stabilized sand dunes are widely spread in this region. Sand fields have high sedimentation rates during episodes of sand accumulation period, hence, it is possible that the sand deposits may record short time climatic changes at certain period. However, due to the potential erosion or hiatus, few successive and high-resolution palaeoclimatic sequences of sand deposits have been reported. This paper present a high-resolution climate evolution record during 4300 - 1000cal, aB. P. derived from sequential aeolian sediments of Liuhutun （ LHT ） section （ 44°28＇N, 123°08＇E ; 151 m a. s. 1. ） in the northeastern frontier of the Horqin sandy land. The 2.96-m sandy paleosol/sandy loess/fine sand section, with a chronological support of 7 radiocarbon dates,has been analyzed at 2-cm intervals（84 -120cm at 4-cm intervals）for grain size distribution（clay,silt, sand contents and Md）, CaCO3 content, organic matter content and environmental magnetic parameters（zlf,XAaM, SIRM et al. ）. Md is considered to represent wind strength and high Md reflects strong winter monsoon winds. CaCO3 content and organic matter content, which denote weathering intensity and the degree of vegetation cover, are chosen as proxies for summer monsoon circulations. The results show that 4300- 3800cal. aB. P. was the warmest and wettest epoch during the study period, with a trend of becoming cooler and drier. The H