| The Eastern Junggar basin,sandwiched between the northern Kelameili Mountain and the southern Bogda Mountain,is an important petroliferous basin,Permian is the main oil source rock.Previous studies indicated that the current Permian tectonic featuresappears a "checkerboard format",which is related to the feature of the Permian prototype basins and the later superimposition and transformatio since Permian.As Eastern Junggar basin is a part of the "Central Asian orogenic belt".The Permian prototype basin and the post-overlying reconstruction process are of great significance to the evolution of the inland tectonic evolution of the Central Asian orogenic belt after the Permian.On the other hand,the tectonic evolution is closely related to the migration,accumulation and preservation of oil and gas.The study has important guiding significance for oil and gas exploration.The purpose of this paper is to analyze the superposition characteristics of current Permian geological architecture in Eastern Junggar Basin,discuss the characteristics of Permian prototype basin and establish a superimposed and retrofitted model from Permian to Neogene.On the basis of previous studies,the paper takes "tectonic evolution" and "basin-mountain coupling" as guidance,discusses the tectono-stratigraphic sequence,tectonic geometry,kinematics and tectonic deformation times,gains three conclusions about the spatial and temporal relationship of tectonic deformation of the Eastern Junggar Basin,just as follows:1.13 horizons' unconformities are recognized through geological survey,log analysis and seismic stratigraphic analysis in the Eastern Junggar Basin.After depicting the temporal and spatial distribution of unconformities,four regional unconformities at the bottom of Middle Permian,the bottom of Cretaceous,the bottom of Paleogene and the bottom of Neogene are confirmed.It is considered that the Junggar Basin experienced large-scale tectonic superimposition in the late of early Permian,the late of Jurassic,the late of Cretaceous and the late of Oligocene.2.According to the fault-related fold theory,the tectonic numerical simulation is used to analyze the tectonic and kinematic characteristics of the main control basin and controlled concave / convex faults.The results show that the present geological architeture of the Permian is formed by the superimposition and transformation of the seven tectonic belts in the north-east,northwest,east-west,‘S-shape'north-north east and north-northwest directions in the multi-stage tectonic movement.In this paper,the Permian is divided into 21 structural units.3.Using the method of fault cutting stratum,unconformity surface,growth stratum and cryogenic thermochronology,the formation sequence and mechanism of seven tectonic belts are discussed.And the “multi-stage and multi-superimposed mode of two-orogen-one-basin”is established.The NW-trending compression-pressure foreland basin is formed by compression of the right bank of the Kelameili faults in Late Carboniferous-Middle Permian.TheEW-trending and "S-shape " tectonic belts are formed by the northward extruding of Bogda faults in the late Triassicperiod.The NNW-trending tectonic belt is formed by the eastward extruding of Western Bogda and the blocking of the Qitai Uplift in the Late Jurassic period.Kelameili faults stopped its activity and formed a NW-trending piedmont tectonic zone in the Late Cretaceous.After the Pliocene,the Bogda faults stopped its activities and formed a NW or NE strike piedmont belt,which meansthe "checkerboard format" structure was eventually finalized. |
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