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湖沼沉积物地球化学元素对地球气候环境变化敏感性强。本文以江西定南大湖湖沼沉积物地球化学元素为研究对象,使用主成分分析法,并结合总有机碳(TOC)、有机碳同位素(δ13Corg)、中值粒径(Md)、化学蚀变指数(CIA)等相关气候代用指标,以元素组对的形式阐释不同地化元素响应不同气候环境下的地球化学行为和迁移规律。研究结果显示:第一主成分(PC1)包括Al2O3、Ti O2、Si O2、Nb、Rb、Ga、Ba、S等元素,曲线变化与CIA相似,指示湖泊流域的化学风化强度,气候暧湿,PC1含量高;第二主成分(PC2)包括Co、Zr、Hf元素,曲线变化与中值粒径较为一致,指示湖泊流域的水动力条件,气候冷干,PC2含量高;第三主成分(PC3)包括Sc、Cu、U、V元素,曲线变化与TOC、δ13Corg含量变化一致。大湖沉积物的物质来源为:在气候暧湿、流域化学风化作用强的条件下,地表径流冲刷流域周边花岗岩风化壳物质并搬运至湖盆沉积,但不排除在冷干时期,风力携带粉尘物质堆积的影响,粉尘物质可能主要源于周边的风化碎屑物。
The geochemical elements of the lake sediments are sensitive to the changes of the Earth’s climate and environment. In this paper, geochemical elements in the sediments of Lake Dahu in Jiangxi Province are studied. Principal component analysis (PCA) is used to study the relationship between sediment geochemistry and organic carbon (TOC), organic carbon isotope (δ13Corg), median diameter (Md) (CIA) and other related climate proxy indicators to explain the different geochemical elements in response to different geochemical environment geochemical behavior and migration rules in the form of element pairs. The results show that the first principal component (PC1) includes elements such as Al2O3, Ti O2, Si O2, Nb, Rb, Ga, Ba and S. The change of the curve is similar to that of CIA, indicating that the chemical weathering intensity, PC1 content is high; the second principal component (PC2) includes elements of Co, Zr and Hf, and the change of the curve is consistent with the median particle size, indicating the hydrodynamic conditions of the lake basin, cold weather and high PC2 content; the third principal component PC3) including Sc, Cu, U, V elements, the curve changes consistent with the TOC, δ13Corg content changes. Substance sources of the Great Lakes sediments are as follows: Surface runoff flushes the granite weathering crust material around the watershed and transports it to the lake basin under the conditions of warm and humid climate and chemical weathering of the river basin. However, it is not excluded that during the cold-dry period, As a result of the accumulation, the dusty material may mainly originate from the weathering debris on the periphery.