Sedimentary Responses Of The Middle Permian Tectonic Evolution In Western Sichuan

This paper takes the Qixia Formation and Maokou Formation of the Middle Permian in the western margin of the Sichuan Basin as the research horizon,and is guided by multidisciplinary theories such as tectonic geology,sedimentology and reservoir geology.Taking full advantage of field survey profiles,typical drilling,logging and seismic data,based on the regional tectonic setting,the sedimentary filling process of the basin is combined with paleo-geomorphic patterns and tectonic evolution characteristics to restore the Middle Permian Qixia Formation and Mao in the western Sichuan Basin.The stratigraphic framework of the Oral Group is used to map the tectonic-sedimentary environment characteristics of each sedimentary period,and the tectonic-sedimentary evolution process is analyzed.The paper has achieved the following results and understanding:(1)In the sedimentary period of the Middle Permian in western Sichuan,the Emei ground motion,the Emei mantle movement and the Soochow movement affecting the sedimentary evolution of the Qixia Formation and the Maokou Formation were sorted out,and the Emei ground motion was considered to occur.A large-scale regional extension of the southern China,and the Emei mantle plume continued to surge,and eventually led to large-scale eruption of basalt.Furthermore,the mantle plume activities are further divided into three stages: the early stage of mantle plume activity and the middle and late stages of mantle plume activity,to discuss their control effects on the tectonic-sedimentary environment evolution of the western Permian in western Sichuan.In the sedimentary period of the Middle Permian in western Sichuan,the relationship between the Emei ground fissure movement,the Emei mantle plume movement and the Dongwu movement during the sedimentary evolution of the Qixia Formation and the Maokou Formation was reorganized and considered to be Emei.The ground fissure movement is a large-scale regional extension in southern China,and the Emei mantle plume continues to rise,and eventually leads to large-scale eruption of basalt.The reason is actually the Emei crack.The most direct manifestation of the intensity of the movement to the maximum activity is also the final product of the activity of the Emei mantle column,which is closely related to each other.(2)Defining the characteristics and evolution of the sedimentary facies of the Middle Permian in western Sichuan.In the sedimentary period of the Middle Permian,it is mainly the carbonate open platform sedimentary system,and further divided into two types of sedimentary subfacies: open sedimentary platform and platform margin two sedimentary subfacies,Taiyuan Beach and Tainean Beach.And from the vertical evolution and longitudinal distribution characteristics,the relationship between planar distribution and spatial superposition is revealed.(3)The coupling relationship between the tectonic-sedimentary evolution of the Middle Permian Qixia Formation and the Maokou Formation in western Sichuan is defined.The Middle Permian sedimentary deposit was developed on the basis of the filling and filling of the Liangshan Formation.It is obviously controlled by the basement structure and sea level rise and fall.There is a certain inheritance between the two,and there are regional differences.Inheritance is manifested in the fact that,with the relative rise of sea level,on the basis of the shore-swamp sedimentary environment of the Liangshan Formation,the study area gradually transitions to a stable carbonate rock open platform sedimentary environment.The difference is reflected in the influence of the sea level rise and fall,the unbalanced uplift of the regional tectonic movement and the differential erosion.The distribution of the sedimentary facies in the area changes with each other,forming different degrees of migration.The sedimentary environment of this period can be divided into basin,platform margin and open platform sedimentary environment from west to east,and each sedimentary facies belt has the characteristics of north-south differentiation and east-west gradual change.A tectonic-sedimentary environment evolution model was established.