Source Of The Holocene Aeolian Loess-soil In The Upper Reaches Of The Yinghe River

Holocene loess-soil profile is studied in this thesis at the Third step terrain of the Shuangjihe River as one of tributary of the Yinghe River in the upper reaches of the Yinghe River. Through field observation, sampling and experimenting, a lot of data of grain-size, magnetic susceptibility and total organic carbon (TOC) indexes at the loess-soil profile are gained, it is analyzed that the connections between the experiment data and sediment environment, soil environment, sedimentary feature of the deposit. The analysis of mechanical grain-size composition and grain-size parameter is emphasized, they are frequency curves, accumulative frequency curves, normal probability accumulative frequency curves, grain-size median, mean size, standard deviation, skewness, kurtosis. It is discussed that the similarity and distinction between the loess substance in the upper reaches of the Yinghe River and that in the Loess Plateau; it is revealed that the source of loess substance and the forming process of loess in the upper reaches of the Yinghe River, and it has importantly actual significance to acquaint the land substance composition and forming process, reveal Holocene loess sediment environment changes, and indirectly reflect soil erosion in the Loess Plateau. According to study, the thesis draws the following conclusions: (1) There are similarity and obvious distinction between the loess substance in the upper reaches of the Yinghe River and that in the Loess Plateau. The contrasting on the grain-size and grain-size parameter for these two regions reveal that there are different wind dynamic system and substance source. The similarity lie in that the thick powder sand is the mostly on grain-size composition of the loess in two regions, and they were formed by the dust carried and pilled up by the wind. The difference of the loess in two regions lies in that the mean size of the loess layer in the upper reaches of Yinghe River is obviously thicker than that in the Loess Plateau, and the standard deviation is little, the skewness is more partial, and the kurtosis is also sharper in the loess layer. But above-mentioned indexes have not obvious distinction in the paleosol. Which show the wind dynamic carrying the dust is stronger in the period during the loess carrying and pilling up in the upper reaches of the Yinghe River, and the near dust was carried and...