巢湖CH-1孔沉积物磁性、粒度特征分析

Magnetic and grain size characteristics of sediments from core CH-1 in Chaohu Lake

通过对巢湖湖心长1.5m的CH-1孔沉积物磁性参数和粒度组成进行测量,探讨了巢湖的沉积环境变迁.结果表明:CH-1孔沉积物以中粉砂和细粉砂为主,其次为黏土.该孔中黏土粒级对磁性矿物贡献最大.自底部向上,该孔分为4段:第1段,沉积物向上粒度变细,亚铁磁性矿物含量减少,亚铁磁性矿物颗粒变细;第2段,沉积物向上粒度变粗,亚铁磁性矿物含量减少,磁性矿物颗粒变细;第3段,沉积物向上粒度变细,亚铁磁性矿物含量增多,磁性矿物颗粒变粗;第4段,沉积物向上粒度变粗,亚铁磁性矿物含量增多,磁性矿物颗粒变粗.上述结果显示:巢湖湖面在整个沉积历史时期呈现上升和下降的交替变化,反映了气候变化对巢湖沉积的影响.

Magnetic and grain size measurements were conducted on core CH - 1 （ 1.5 m in length ） from Chaohu Lake to study the environmental changes of the lake. The results show that sediments of core CH - 1 are mainly composed of medium silt, fine silt, and a little clay. The magnetic minerals are mainly contained in the clay. From the bottom to the top of the core, the sediment can be divided into four sections. In section 1, sediment grain size and particle size of ferrimagnetic mineral decrease upward, While the content of ferrimagentic mineral increase. Section 2 shows that the sediment grain size becomes coarser gradually upward, and the particle size of magnetic minerals still decrease, while the content of ferrimagnetie mineral becomes less. In section 3, sediment grain size becomes finer upward and the particle size of magnetic minerals becomes coarser upward, while the content of ferromagnetic minerals increase. In section 4, the sediment grain size and the particle size of magnetic minerals become coarser upward and the content of ferrimagnetic minerals increase. The study results indicate that the water level of Chaohu Lake fluctuated during the past, revealing the past climate ehangings.