| Because in the middle reaches of the Yellow River in the activities of the special tectonic position of ordos massif, middle reaches of the Yellow River of E Mei platform near ordos massif east edge, its evolution history research is to understand and investigate the remote effects of qingzang-tibet plateau scientific problems such as important way, on both sides of the middle reaches of the Yellow River of E Mei platform found lacustrine carbonate platform, platform and different regions, different altitude of underground of the lacustrine sediments of the loess, paleosol sequence is not the same, according to the topography and geological map, and loess- paleosols sequence method, using the Core Draw drawing software, in turn, make different terrace loess section, E Mei platform roughly divided into three sub, the highest level of underground by loess-paleosol sequence is S14 paleosol, about 1.09 Ma b. p. forms. The second higher level of underground by loess-paleosol sequence is L9 formation was about 0.85 Ma b. p.(D S liu, 1985), the third lowest station underground overburden layer of loess- paleosol sequence is S1 paleosol and L2 loess respectively, forming were about 0.13 Ma b. p with between.0.25 and 0.13 Ma b. p. Loess- paleosol sequence through the platform of the first layer is directly covered in loess deposit, we determine three secondary platform should be related to the formation of the wei river basin and lin fen basin with the three movement of lake retreat, because the wei river basin in L9, L6, L2 loess development occurred during the period of the three big lake retreat movement, and also in lin fen basin S8, S5, S1 paleosol development occurred during the period of the three big lake retreat movement, the two lake retreat movement is caused by the tectonic uplift movement, so E Mei platform level 3 secondary platform formation is associated with three big tectonic uplift. Because E Mei platform is located in between wei river basin and lin fen basin, because of the tectonic uplift movement, there is a lag in time, so E Mei platform closer from the wei river basin, the tectonic uplift movement occurred earlier, and the loess, paleosol sequence layer older; And closer from the lin fen basin of E Mei platform, the tectonic uplift movement occurred in late, and the loess, paleosol sequence layer is relatively young. E Mei platform before the lift is covered by the ancient san men lake, so E Mei platform lift for the last time in S1 paleosol development period, can correspond to the demise of the ancient san men lake. At the same time, according to the literature and investigation, the Yellow River cutting wear after E Mei platform, the ancient san men lake and well versed in san men lake Yellow River flows into the east sea are consistent, remains to be further research and textual research. This thesis mainly the following conclusions:(1)E Mei platform as a whole is tilted from north to south, because there was too much of tectonic movement in the middle reaches of the Yellow River, the or dos massif tilted to the north, and E Mei platform tilted to the south, resulting in S14 paleosol development after all bedding loess – pale sol sequence is tilted shaped.(2)E Mei platform is a transitional platform, north and south on both sides of the platform of the loess, paleosol sequence is different. And E Mei platform has three secondary platform, this triple terrace with Fen river nutrient-laden down faulted basin of a massive lake retreat for three times.(3)E Mei platform by three large-scale tectonic uplift was Yellow River cut through the before, based on the research analysis middle Yellow Rive of geomorphic evolution history, this will be for the whole evolution history to provide more evidence in the middle reaches of the Yellow River. |
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