Characteristics of tectonic zoning and formation and evolution of the pre-mountain folded-alluvial belt in the western part of the southern margin of the Junggar Basin
The interpretation of high-precision seismic data reveals that the tectonics of the western part of the southern margin shows new tectonic superposition characteristics and more complex superposition composite tectonic style,and the superposition tectonics has obvious zoning characteristics in spatial dis-tribution.Combined with the field geological investigation,seismic interpretation,equilibrium section restoration,and the use of wedge tectonic theory and tectonic geology analysis methods,the complex superposition tectonic deformation differences and zoning characteristics were investigated.The study shows that:the western part of the southern margin develops a spatial folding system under the joint and differential control of basement involvement and downstream sliding,and the development of folds is controlled by faults,which are superimposed on each other to form a tectonic wedge,double tecton-ics,sudden tectonics and other composite tectonic styles.The western part of the southern margin is di-vided into three tectonic belts,namely,the pre-mountain retrograde thrust-overthrust tectonic belt,the basement-involved fold-rupture belt,and the cover-slip fold-rupture belt,according to the nature of the tectonic deformation and the difference of the deformation,among which the basement-involved fold-rupture belt is overlapped with the first row of the fault belt and controlled by the basement-involved rupture system,and the large-scale tectonic wedge of basement-involved,the dual structure of the dor-sal stacking and double-tectonics,and the double-tectonics of the forward-dipping tectonics are devel-oped,and the dorsal axes overlap the planes of faults with high coincidence degree.The slip-type fold-rupture zone includes the second and third rows of fold zones,which are controlled by the downstream slip-type rupture system,with the development of break-spreading folds,low overlap between the dor-sal axes and the fault line planes,and layered differences in the vertical direction of the tectonics;the o-verall degree of tectonic deformation from the south to the north shows that it is decreasing from strong to weak.The period and intensity of extrusion stress,the northward slip of the slip fault,the wedge length of the tectonic wedge and the pushing distance,the thickness of the slip layer and the thickness of the overlying strata,the depositional age,the depositional rate,and the difference in lithology are the causes of the vertical stratification of the tectonics of the western part of the southern margin and the north-south division of the zone.The explicit construction of deformation differences and the refined di-vision of zoning have important implications for clarifying the development of geological structures in re-search areas and guiding oil and gas exploration activities.
western part of southern margin of Junggar Basinpre-mountain beltthrust and nappe tec-tonic beltfold-thrust beltconstruct stylestructural deformationzoning characteristicstectonic evo-lution
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