Geological Structure And Dynamic Characteristics Of Dejiang Area In Guizhou Province

The Dejiang area in Guizhou is located in the uplift area of the northern part of the Upper Yangtze block.Sedimentary strata are widely developed in the study area,and after a series of geological structure transformations,special structural patterns are formed.Through field observations and laboratory studies of rock formations,folds,and fault structures in the study area,the geologic structure,deformation,kinematics,and dynamics of the geological structure in the study area were analyzed,and the geological structure and tectonic evolution of the geological structure were investigated.Analysis,discussion.On the basis of summarizing previous studies,combined with field investigations and analysis of indoor data,the following points were learned about the structural characteristics and evolution of the Dejiang area:?1?According to the geological structure deformation pattern,deformation strength and spatial distribution law,the study area is divided into two types of deformation areas and four deformation units:?1?Western linear strong deformation area?I?:closed-intermediate constant folding/shingled inverse Thrust layer combination;?2?Medium-western basal uplift weakly deformed area?II?:Broadly backdip/stepwise normal fault combination;?3?Central-eastern strong linear deformation area?III?:Closed anticline/tenant?passive?Angular/Hedging thrust fault combination;?4?Eastern basement uplift weak deformation zone?IV?:Broad back-slope/normal fault combination.?2?The geological structure of the Dejiang area has undergone long-term geological structural evolution and formed a complex geological structure.The Wuling orogenic movement formed the crystalline basement and basement faults in the study area;the Guangxi movement made the Xiushan Formation?S₁x?and the Liangshan Formation?P₂l?into parallel unconformity contact;the Yanshan-Xishanian geological tectonic movement laid the foundation for the present The main structural pattern.?3?According to the structural deformation characteristics and the combination of regional structural analysis,it is preliminarily assumed that the Yanshan-Xishan period geological structure development-evolutionary model can be divided into four stages:?1?the original stage:the overall rise and fall of the substrate,cap layer deposition;?2?Initial folding stage:The cover is affected by the regional EW toward the extrusion and the SN counterclockwise couple to form the initial fold,and the nucleus is subjected to longitudinal tension to form a longitudinal fault;?3?Stages of fault block dislocation?disruption?:The basement block breaks,and the diamond block forms a broad dome anticline.The caprock of the Qianlong anticline diverges along the faults,forms a tightly closed anticline and a broad obliquely passively,forming a partition-type folding combination;longitudinally extending faults.Forming a stair-like combination;?4?Fault-breaking bend-breaking phase:The continuous rupture of the basement fault block,the cracking of the capping layer,the formation of tight folds,and the further development of the stepped fault.