Objectives:Based on the analysis of the tectonic stress field of SE Sichuan,the paper discusses the revolution characteristics of the tectonic stress field,the mode of action and the sequence of tectonic stress in the SE Sichuan using structural analysis methods.Methods:Through a survey on many structural features in the Southeast Sichuan Dingshan area,which include vertical folds,conjugated joints,etc.,we investigated the revolution characteristics of the tectonic stress field,mode of action and sequence of tectonic stress in the Dingshan area by structural analysis method.Results:The results show that the region experienced four periods of function of tectonic stress field which came from four different directions:NW,nearly SN,nearly EW and NE.The force of NW appeared early than that of nearly SN,and then the compression of nearly EW,the last NE.We concluded that the structural framework of the study area has been formed by the effect of compression stress of NE—SW which is still active today.Condusion:Following the analysis of orientations and stages of structural stress in southeastern Sichuan,we found that structural stress sources in the region were closely related to the structural evolution in the whole southeastern Sichuan region.The SE Sichuan basin is jointly controlled by the Xuefeng and Tibet structures.The intra-continental orogenic system of Xuefeng during the late Cretaceous occurred during a period of NW—SE-trending extensional deformation.The edges of the SE Sichuan basin formed a series of NE—SW-trending structures,for which deformation occurred in the Palaeocene stage.At the end of Eocene,due to the strong bending of central Guizhou along with the Ziyun—Luodian Fault in Daloushan and a strong barrier of rigid substrate beneath the Sichuan basin,Daloushan and southern Sichuan bore nearly N—S-trending extrusion which resulted in nearly E—W-trending structural deformation.In the early Oligocene,the Daliangshan structural belt began to undergo structural deformation and coincident with this,collision of India and Asia responded remotely to form E—W-trending extrusion in southeastern Sichuan region.Since the Late Oligocene,continuous collision action has been ongoing between India and Asia.The Daliangshan structural belt has experienced a gradually increased deformation intensity,which has expanded to the interior of the basin and formed NE—SW-trending extrusions,resulting in the formation of NW—SE-trending structures in the region including the ChangningShuanghe anticline.%细致辨析构造应力对研究区域作用方式和转换形式,对页岩气保存条件评价具有重要的指导意义.通过研究直立褶皱、共轭节理等各种构造形迹,采用构造解析分析方法,研究川东南构造应力场演化特征.同时在构造应力场地质分析的指导下,运用构造形迹叠加分析的方法及定年分析,清晰刻画了川东南构造应力作用方式以及期次,认为川东南主要受到四期不同方向构造应力作用,其中NW向挤压应力最早影响到研究区,形成控制研究区主体构造特征的NE向构造;其次是近SN向挤压应力对研究区的作用,发育一系列及EW向构造;随后印—亚板块碰撞远程响应在川东南形成EW向挤压,形成近SN向构造;最后NE—SW向构造应力是渐新世晚期以来一直影响研究区活动的主要动力来源,并对早期油藏进行改造和调整.川东南龙马溪组页岩气受到多期构造联合作用的影响:燕山晚期NW向挤压应力作用,致使研究区褶皱变形;渐新世晚期以来的构造活动,导致研究区大范围隆升剥蚀,断层出露地表,影响了页岩气保存条件的有效性.
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