Structural Characteristics And Evolution Of Nappe To The South Of Fufeng Fault In Huainan Area

The nappe structure in the south of Fufeng in Huainan area is located in the south margin of North China plate.The present tectonic pattern has been formed in the long-term geological evolution.Through the study of nappe structural system in the southern Huainan area,it not only provides the basis for the prevention and control of geological disasters and the exploration of coal resources under the nappe,At the same time,it also provides theoretical basis for the prevention and control of water damage and the design of coalbed methane mining in abandoned mining areas.In this paper,the geological structure types,geometric forms and structural evolution history of the research area are studied by field geological survey,structural statistics and evolution methods from the aspects of typical section characteristics,macro geological structure characteristics and dynamic characteristics,and the following conclusions are drawn:(1)The strike of the research area is from east to west to west,and consists of a series of South dipping thrust faults,which are mainly developed in Proterozoic Paleozoic strata.(2)The study area is divided into three fault blocks:the first block is the part enclosed by the shungenshan and Fuli faults,the stratum trend is near EW,the stratum is vertical or reversed,and the formation occurrence has gradual change;The second fault block is the part of Fufeng fault,Shanwangji fault and Fuli fault.The stratum trend is NW-SE,and no reverse occurs.The area is characterized by translational faults.The fault is divided into Bagongshan and Fengtai rock slices,and the formation occurrence on both sides is obviously different;The third fault block is the part of the limit between Fufeng and Fuli faults.The Fufeng fault and Fuli fault converge each other in the area,and the geological structure is deeply influenced by Fufeng fault.(3)Through the restoration of paleotectonic stress field,it is concluded that the study area has experienced two stages of tectonic movement,namely NNE-SSW movement and NWW-SEE movement.(4)Combined with the regional geological evolution background of the study area,the formation of nappe structure south of Fufeng originated from the early compression of Indosinian Yanshan movement.Under the action of the regional NNE-SSW compression stress,Fufeng fault,Shanwangji fault,shungenshan fault and Fuli fault began to form.By the middle of Yanshan Movement,due to the shortening of NWW direction,the early formation of thrust faults has a tendency to normal fault.The transformation of Fuli fault into normal fault promotes the formation of Hefei basin.The Sanwangji fault divides the Bagongshan block into two,and the south thrust of Fufeng in Huainan area reflects the formation of present geological structure.Figure[42]Table[4]Reference[72]...