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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、CaCO,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χ_ARM/χ_LF和χ_ARM/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,χ_ARM/χ_LF和χ_ARM/SIRM与成壤作用表现为反相关。
The Liuhuatun section located at the northeastern margin of Horqin sandy land was selected as the research object. The time series of aeolian sediment deposition was established by using 7 conventional ~ 14C ages. The sediment grain size, CaCO content, organic matter content and environmental magnetic index Systematic analysis and reconstruction of the climate evolution history of 4300-1000 cal.aB.P. in Horqin area. The results show that 4300 ~ 3800cal.aB.P. is the end of the Holocene, which is the warmest climate in the study area, and the degree of warming and wetting tends to decrease. 3800 ~ 1700cal.aB.P. Climate period, of which 3000cal.aB.P. is the node of climate evolution, the early climate gradually transition from warm and humid to dry and cold, the latter part of the winter monsoon continued strong, the summer monsoon gradually restored; 1700 ~ 1000cal.aB.P. Wet climate, climate conditions are warm and humid, but less than the Great War period. In addition, the environmental magnetic studies found that the magnetic particle size parameters χ_ARM / χ_LF and χ_ARM / SIRM can be used as a proxy for climate, and the commonly used magnetic susceptibility parameters indicate ambiguity in this study. Since native detritus magnetic minerals have reached a stable single domain (SSD) size, χ_ARM / χ_LF and χ_ARM / SIRM are inversely correlated with soil formation.