论文部分内容阅读
以福建闽江大横红土剖面为例,通过系统的粒度特征分析,探讨闽江二级阶地上红土沉积的成因及其古环境响应.研究结果表明:大横剖面红土的粒度组成以粉砂为主,分选较差,峰度平缓,表现出近源物质混杂堆积的特点.剖面不同层位之间的粒度组成表现出明显不同的特征,0~6.5 m层位红土以粘质粉砂颗粒为主,粒径变化随深度波动缓和,推测为近源高处古土壤或碎屑物质在降雨或坡面径流的侵蚀作用下向地势平缓的地区搬运沉积形成;6.5~8.9 m红土随地层深度增加中值粒径迅速增大,并在7.5 m以下出现剧烈波动,这样的粒级变化特征结合沉积层内存在多量植物根孔和碳屑的现象,推测该层可能是较大的古洪水爆发携带大量山地古土壤和风化壳碎屑物质在阶地上快速沉积的结果;8.9~11.3 m红土粒级波动无规律,分选性差,表现出河漫滩相沉积的特征.
Taking the red clay profile of Minjiang River in Fujian Province as an example, the sedimentary genesis and paleoenvironmental response of the laterite clay in the second terrace of the Minjiang River were studied by analyzing the granularity characteristics of the system.The results show that the grain size distribution of the laterite is large, The main, poor sorting, kurtosis smooth, showing the characteristics of mixed deposition of near-source materials.The grain size distribution between the different layers of the section showed obviously different characteristics, 0 ~ 6.5 m layer of laterite to clay silt particles The variation of grain size with the fluctuation of depth is presumed to be that sediments of ancient soils or debris near the source are transported to the flat terrain by the rainfall or runoff erosion. The increase of median diameter increased rapidly and fluctuated below 7.5 m. This feature of grain-size variation combined with the presence of a large number of plant root pores and carbon debris in the sediment layer suggests that this layer may be a larger paleo-flood Carrying a large number of mountain ancient soil and weathered crust detrital material quickly deposited on the terraces results; 8.9 ~ 11.3 m red soil particle size fluctuations irregular, poor sorting, showing the characteristics of river floodplain facies.