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利用巢湖ACN钻孔,通过多参数磁性测量、粒度和AMS14C测年分析,探讨了近7000年以来巢湖沉积物磁性特征变化及其控制因素,并进而探讨了其对亚洲季风变化的指示意义。研究结果表明,ACN钻孔磁性特征由磁铁矿主导,其变化主要受沉积动力环境控制,间接反映了流域降水的变化。总体上粘土含量高的沉积物中磁性矿物含量较低、颗粒较细,形成于高湖泊水位环境,对应了降水量高的时期;而>32μm组分含量高的沉积物磁性较强、颗粒较粗,形成于低湖泊水位环境,对应了降水量低的时期。巢湖ACN的磁性记录(尤其是ARM/和ARM/SIRM两个参数)揭示了近7000年以来巢湖流域降水具有减少的趋势,导致湖泊收缩和沉积物中磁性矿物颗粒变粗。在这一长期变化的基础上,还存在6000aB.P.,5500aB.P.和3800aB.P.附近的显著干旱事件。这一磁性记录与中国东部地区的石笋、湖泊等记录可以很好地对比,是亚洲季风演变的区域响应结果。
Based on the multi-parameter magnetic measurement, particle size and AMS14C dating, the magnetic characteristics of Chaohu Lake sediments and their controlling factors were explored with the help of ACN drilling in Chaohu Lake. The significance of these changes to the Asian monsoon was also discussed. The results show that the magnetic characteristics of ACN boreholes are dominated by magnetite, and the change is mainly controlled by sedimentary dynamic environment, which indirectly reflects the change of precipitation in the basin. In general, the sediments with high clay content have lower content of magnetic minerals and finer grains and formed in high lake water level environment, corresponding to the period of high precipitation. The sediments with high content of> 32μm are more magnetic and the grains are more Coarse, formed in the low lake water environment, corresponding to the period of low precipitation. The magnetic records of ACN in Chaohu Lake (especially ARM / and ARM / SIRM) reveal that the precipitation in Chaohu Lake basin has been decreasing since the last 7,000 years, leading to the shrinkage of the lake and the thickening of the magnetic minerals in the sediments. On the basis of this long-term change, there are also significant arid events around 6000aB.P., 5500aB.P. And 3800aB.P. This magnetic record is well matched with records of stalagmites and lakes in eastern China and is the regional response to the evolution of the Asian monsoon.