宣城向阳剖面网纹红土粒度端元分析及指示意义

对宣城向阳剖面的109个网纹红土样本做粒度分析和地球化学元素分析,并对粒度数据采用合适的端元分解方法,将各端元与地球化学指标在深度上进行了对比。结果认为:端元法可以把代表此区域3种不同动力的沉积端元(EM)分离出来,并可以定量地分析各自所占比重及各个阶段每种动力各自的沉积变化。EM1明显指示着对原有沉积物的成壤改造作用;EM2可能代表着东亚冬季风作用下经远距离悬浮搬运并在湿润的宣城地区沉积而受到化学风化影响的组分;EM3则比较明显地代表着受东亚夏季风作用下的化学风化及近源搬运作用。各端元在深度上的变化过程一定程度上揭示了区域气候背景的变化信息,为更进一步的气候变化研究及网纹红土中网纹成因研究提供了一种新的思路。

End Member Analysis on Grain Size of Reticulated Red Clay and Its Indication Significance in Xiangyang Section of Xuancheng

Grain-size analysis and geochemical element analysis were carried out on 109 reticulated laterite samples from the Xiangyang section of Xuancheng, and appropriate end-member decomposition methods were used for the particle size data to compare each end-member with geochemical indexes in depth. It showed that the end member method can differentiate the three sedimentary end members with different dynamics in this area, and can quantitatively analyze the respective proportions and the respective sedimentary changes of each dynamic in each stage. EM1 clearly indicates the pedimentation and transformation of the original sediment; EM2 may represent the components affected by chemical weathering after long-distance suspension transport and deposition in the humid Xuancheng area under the action of East Asian winter monsoon; EM3 obviously represents chemical weathering and proximal transport under the action of East Asian summer monsoon. The depth change process of each end member reveals the change of the regional climate background to a certain extent, and provides a new idea for further research on climate change and the cause of reticulation in reticulated red soil.