The Time Series Difference And Significance Of Quaternary Stage Evolution In Shanxi-Shaanxi Graben

Shanxi-Shaanxi graben,north from the Yanshan and south to Qinling, located in the southern and eastern Ordos plateau edge since Pliocene. The graben system is one of the strongest new tectonic movement places in China, from southwest of the Yanqing County in Beijing, through Hebei Province, Shanxi Province and Shaanxi Province, distributed by the normal fault the enclosed rift basin.The faultage basin in graben system gathered water into lake, occupied by the lake in a very long period time in Quaternary. Influences by tectonic movement and climate, the pattern of all faultage basins in Shanxi and Shaanxi have experienced a number of lake transgression and regression changes, the evolution of the River– Lake's environment, formed series of lacustrine or lake erosion terrace and fluvial terraces during the Middle and late Quaternary.This area lies in the loess field, with the decreases occurred in the lake area when the lake retreat, the lake water will be exposed gas deposits to acceptance of loess; while the increase occurred when the lake transgression of the lake area, the water will swamp the loess deposits of the lake sediments. Therefore it emerges the phenomenon we see in the wild: different periods of lake sediments range of large or small in the horizontal direction; lacustrine deposits and fluvial or aeolian deposits were interbedded in the vertical direction. If the lake level is above the S1 paleosol accumulation, it indicates that during the S1 paleosol development stages, regression occurred in the area of the lake regression, If the lacustrine deposits covers the S1 paleosol layers above the note during the period of the S1 paleosol development, in means that the lake transgression occurred in the area.The reach results show that the reasons of occurring the tectonic movement that changes the scope of the ancient lake led to a significant lake regression. In fact, in the late Quaternary, Shanxi and Shaanxi graben system took place three times intense tectonic movements in the Weihe basin led to the formation of three river terraces, In Linfen - Taiyuan and Datong Basin Basins (Nihewan Basin) have led to three large-scale events lake retreat. The first movement occurred during the L9, S8, L8 loess - paleosol development period, The second movement occurred during the L6, S5, L5 loess - paleosol development period, The third movement occurred during the L2, S1, L1 loess - paleosol development period. But for all the faultage basins of Shanshan graben system, tectonic movement occurs every time but not at the same, Weihe basin are the first place, then Linfen - Taiyuan Basin, finally Datong Basin. The incidents are similar to the Pleistocene Kunhuang and Gonghe movements.From the time series and differences of the Weihe basin, Linfen - Taiyuan Basin, Datong Basin in Quaternary, we can see that Qinghai-Tibet Plateau in Queensland occurred since the Pleistocene,Kunhuang and Gonghe movements are influential on the external area. It also reflects that the influences of the uplift of the Qinghai-Tibet Plateau are step by step and gradually, from the south to the north. The formation of the differences in time series has a relation with the crustal stress occurred by the uplift of the Qinghai-Tibet plateau, the evolution from the Weihe basin to the Datong Basin has an obvious impact on the uplift of the Qinghai-Tibet plateau.