Junction and Transition of Meso-Cenozoic Intraplate Deformation between Taihang Mountains and Qinling Mountains
CHENG Shixiu;LI Sanzhong;XU Liqing;YU Shan;CAO Xianzhi;WANG Pengcheng;SUO Yanhui;LIU Xin;ZHAO Shujuan;XIONG Lijuan;Key Lab of Submarine Geosciences and Exploration Techniques,Ministry of Education;College of Marine Geosciences,Ocean University of China;
During Mesozoic and Cenozoic, the Qinling Mountains is a E—W-striking uplifting central mountains separating North China from South China in geography,while the Taihang Mountains is a S—N-striking uplifting mountains in the Central North China Block in geology,but their strikes are perpendicular to each other.In order to investigate exhumation,uplifting history and transition of tectonic stress fields between these two mountains within the interior Eurasian Plate,by systematic comparison and analysis of their regional compressive and extensional tectonics,and contrast transitions of Mesozoic and Cenozoic tectonic regimes,this paper concludes that transition time of Mesozoic and Cenozoic tectonic regime is about the late Early Cretaceous. Through analysis and comparison of coeval stress field in different tectonic units,it reveals that their shortening and compressivedeformation is related to intraplate heterogeneity of lithosphere structures caused by formation of ancient orogenic belts,and their extensional deformation is closely related to penetrative intraplate rifting in East China. Therefore,the extensional tectonics shows the formation of wide rift valleys of which overall tectonic framework is inherited from its pre-existing basement tectonic framework. In short,the difference of intraplate deformations is controlled by pre-existing basement tectonics,and the responses of complex pre-existing boundaries of different intraplate blocks to geodynamics at plate margins are so different. After removing a far-field effect of plate subduction,the intraplate deformation mechanism itself may be closely associated with heterogeneity of intraplate thermal— mechanical structures.