The Formation Mechanism And Hydrocarbon Accumulation Of Transverse Fault In Thrust Belt Of Southern Junggar Basin

The transverse fault is a fault that is perpendicular or oblique to the regional structure or the main body of the basin.The southern margin of the Junggar basin developed typical foreland thrust belt system,where transverse faults widely developed.The research of the characteristics and formation mechanism of this faulted structure can not only assist us to profoundly understand the tectonic pattern of southern Junggar thrust belt but also guide us into the exploration prospective in this zone.Identifying the transverse faults is first and foremost work,based on the data of landform remote sensing,gravity and magnetic field and 3D seismic data,13 transverse faults were identified in the south of the South thrust belt.In the plane,these transverse faults which had the characteristics of left-lateral or right-lateral(NNE or NNW)distributed in a group.In the seismic profile,these transverse faults performed as the bifurcation,flower structure and other features,the fault surface is steep and the blocks on both sides of the faults appeared as random distribution.On the satellite map,it can be clearly seen that the two disks of the transverse faults have a relative sliding phenomenon,and were split with other fractures and anticlines.The formation of transverse fault can be divided into two kinds: pre-existing regional faults(NNE)and the main thrust rushed active faults caused by differences in the regulation of fault.These transverse faults are associated structural components of thrust and nappe tectonics structure of the thrust belt in Quasi South,and remained thrust and strike slip properties.The control effect of the cross section of the thrust belt on the oil and gas is eventually discussed in this paper.The development site of the transverse faults is usually the entrance of the mountain stream into the basin.Good reservoirs well developed along the steep slope of alluvial fan,fan delta fan;the main thrust fault,transverse faults and anticlines formed fault noses,fault blocks and other types of structural traps and composite traps,the main thrust fault and transverse layer can connect oil source and reservoir,making these traps effective traps.According to the reservoir trap models,oil and gas vertical distribution pattern is established: oil and gas migrated and transported mainly along the thrust faults and transverse layer,forming reservoir in anticline trap.