秭归盆地中—新生代多期叠加改造变形特征研究OA

This article focuses on the intracontinental tectonic deformation of the South China Plate in southeastern Eurasia since the Mesozoic-Cenozoic era,taking the Zigui syncline as the research object,and using structural analysis methods to analyze its superimposed deformation process.The Zigui syncline is located at the intersection of the northern margin of the South China Plate,the front edge of the Daba Mountain arc-shaped structural belt,and the northern edge of the Xuefengshan thrust system,and has an overall"basin type"syncline structural style.This basin witnesses and records detailed information on the intracontinental tectonic deformation of the South China Plate since the Late Mesozoic era,and is the best window to reveal the characteristics of intracontinental tectonic deformation in the South China Plate.Based on previous research,this article reveals through field structural analysis that the Zigui syncline has undergone three stages of structural deformation since the Late Mesozoic era.The first phase of deformation(D1)is characterized by the development of NE-SW trending synclinal structures in the Jurassic and its underlying strata.The inversion results of the paleo-stress field indicate that it was subjected to near NW-SE compression.Combined with the regional stratigraphic contact relationship,the deformation time of this phase of structure is limited to the end of the Jurassic period,and the power source is the northwest subduction of the ancient Pacific Plate.The second phase of deformation(D2)is manifested as the superposition and transformation of pre-existing NE-SW structures by near NNE-SSW compression.Combined with regional geological data,the deformation time of the structure is limited to the Late Paleogene period,and the power source is the uplift and expansion of the Qinghai-Tibet Plateau caused by the subduction of the Indian Plate into the Eurasian continent.The third stage deformation(D3)is characterized by a series of nearly N-S trending compression structures developed under the compression of the E-W direction.Based on the regional tectonic uplift event,the deformation period of this period is the Late Neogene,and its driving force comes from the eastward expansion of the Qinghai-Tibet Plateau.