Structural deformation and origin of the arcuate fold-thrust belt in western Hubei Province
Wang Ping1, Liu Shaofeng2, Wang Kai3, Gao Tangjun4
1. Earth Science and Engineering, Nanjing University, Nanjing 210093;
2. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083;
3. Xi'an Institute of Geology and Mineral Resources, Xi'an 710054;
4. SINOPEC Exploration Southern Company, Chengdu 610041
In northern Yangtze area,there are two Mesozoic arcuate fold-thrust belts,the southern Daba fold-thrust belt and the eastern Sichuan-Western Hubei fold-thrust belt.The origin of the southern Daba was due to the large arc-shape indentor(northern Daba divided by Chengkou-Fangxian thrust fault)and two basement uplift(Micangshan and Shennongjia),but the origin of the eastern Sichuan-Western Hubei fold-thrust belt was not well understood.Based on the cross sections and field mapping,this paper analyzed the geometry and kinematics of the folds and faults in western Hubei province.We found that the fold-thrust belt was characterized by multi-phase deformation.The early phase deformation was dominant by straight fold trending NEE.During the propagation of fold-thrust belt,the eastern and western limbs were developed with curved folds trending NNE and NWW,respectively.The strike-slip faults with opposite slip direction were also formed in the two limbs.The late phase deformation was concentrated in the central fold-thrust belt,characterized by NNE-trending fold and NNW-trending strike-slip fault.The NNE-trending folds superposed on the NEE-trending folds,while the NNW-trending fault cut across the NWW curved in the eastern limb.The two-phase deformation suggested the varied structural stress field controlled by different factors.We conclude that the arcuate fold-thrust belt is orocline with vertical-axis rotation in western Hubei Province.The early phase deformation was controlled by detachment horizons.The late phase deformation was controlled by Huangling basement uplift,which held the propagation of eastern limb of the fold-thrust belt and intensified the curved deformation.