Evolution And Dynamics Mechanism Of Weihe Graben

The Weihe graben is a rift basin developed in the late Mesozoic-Cenozoic which hold in the Qinling orogenic belt and Ordos basin.This paper taked Qinling orogenic belt, Weihe graben and Ordos basin as a interrelated dynamic system for study by the time limited for late Mesozoic-Cenozoic.Research focused the relationship between the developoment of the Weihe graben and Qinling orogenic belt,Ordos basin tectonic changes,discussed the structure development,sedimentary evolution and characteristics of dynamics of Weihe graben.Research taked "Decomposition,Dynamic and Comprehensive" three principles for guidance, used the method of geology,geophysics,geodetic survey and mathematical simulation to analyze the relationship between Qinling orogenic belt, Qrdos basin and Weihe graben. Specific research methods are widely collect and research materials and previous research results,combining with a certain amount of field work; beginning the work based on regional tectonics,topography,sediment characteristics and geophysical; research of the coupling relationship of the Weihe graben developmental process and its surrounding tectonic movement which the main line is the Weihe graben sedimentary response to its surrounding areas.Research shows that:(1)The formation and development process of weihe graben can be well correspond with the surrounding tectonic events,which can he divided into 4 stages (K2-E1,E2-N2,Qp,Qh).(2)Since 20±(2-4)Ma, the Qinghai-tibet plateau aggregate effect and remote effect on the surrounding area.Sedimentary characteristics of the Weihe graben can correspond well up with Qinghai-tibet movement, Kunhuang movement, Gonghe movement. (3)North Qinling large normal faults, ladder shaped normal faults of north Weihe are the main fractures which control the development of the Weihe graben. They are characteristics for development time early, active strong, different geological era succession.In addition, there are some EN-NNE and NW flaws which control of the internal structures and sedimentary framework of the Weihe graben with 3 main faults.(4)Nowadays the structure of Weihe graben is joint influenced by the horizontal structural force,the mantle protrusion power and the gravity of sedimentary. The mantle protrusion power is the main factor of tensile environment of the Weihe graben.