Discovery and exploration significance of loess in Xiaoqinghe River drainage, Shandong Province

Key words:  Xiaoqinghe River drainage  loess  grain size  genesis  exploration significance

Abstract:

The characteristics of shallow sediments in the south of Xiaoqinghe River drainage, Shandong Province were studied by using samples from drilling holes, field study and grain size analysis. The results show that the shallow sediments in the south of Xiaoqinghe River drainage are mainly argillaceous silt and silty mud. The sediments consist of loess markers including calcareous concretions and snail fossils and develop obvious sedimentary cycle of loess-paleosol. By analyzing grain size of the samples systematacially and contrasting those samples with some aeolian sediments such as Qingzhou loess, Xifeng loess and dust fallouts in Beijing, it is proved that, loess from the study area carries the typical characteristics of aeolian loess in China which possesses the typical double-peak feature in grain size frequency curves. Furthermore, it is evident that the average grain size is larger than that of dust fallouts in Beijing and Xifeng loess, but is coarser than that of Qingzhou loess or resembles, which reflects a nearer provenance. The main provenance of loess in the study area is the exposed Bohai continental shelf during the last glacial period. The monsoon in the eastern China and mountains in the south area of Xiaoqinghe River drainage provide transporting force and topographic condition for the formation of loess in the study area. Paleochannels develop in the northernmost of the drainage, and there is a transitional zone between the loess and paleochannel. The depth of water table in the south of the drainage is greater than that in the north because of the difference of sedimentary characteristics and topography. The difference finally results in that the excitation effect in the north is much better than that in the south.