| In the late Mesozoic,the periphery of the Ordos block formed boundary extruded tectonic belts with different distribution directions.A large-scale thrust nappe structural belt is developed in the northwestern margin of the Ordos block,with complex structural deformation characteristics and patterns.Therefore,this paper selects the northwestern margin of the Ordos block as the research area,and takes multiple NE-SW thrusts and their symbiotic fold structures as the research objects.Through the fault slip vector,the conjugate joint occurrence and the fold two wings To collect the occurrences,use the“faultkin”and“stereo”software to invert the paleo-structural stress field,analyze the structural deformation patterns in the study area through the measured section and detailed field investigation,and use the“2DMOVE”software to restore the balanced section and calculate the research The amount of structural shortening in the area.Through the above methods,the structural deformation characteristics,structural stress field inversion results and structural shortening of the study area are obtained.Combined with regional structural analysis,the following points are mainly obtained:This paper believes that the intracontinental deformation in the northwestern margin of the Ordos block is dominated by strong upper crustal shortening,which is manifested as a series of thrust-fold deformations,and tectonic activity occurred in the Late Jurassic;the tectonic stress field of intracontinental deformation appears as NW-SE Extruded towards the structure,?1=124°?6°??2=212°?7°??3=337°?80°,the crustal shortening caused by intracontinental deformation in the northwestern margin of the Ordos block is 1.6-14.5km,and the shortening rate is 11.5-32.1%,and the crustal shortening deformation in the northern Helan Mountain area is greater than that in the Zhuozi Mountain area,and provides a basis for the study of the Late Mesozoic intracontinental deformation around the Ordos block. |
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