EPOCHS AND SPACE-TIME MIGRATING OF MESO-CENOZOIC THRUST-NAPPE TECTONICS IN THE NORTH QINLING-DABIE OROGEN
Sun Xiaomeng1, Wu Genyao2, Hao Fujiang1, Zhang Meisheng3, Liu Pengju3
1. Faculty of Applied Technology, Jilin University, Changchun 130022; 2. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029; 3. Faculty of Earth Sciences, Jilin University, Changchun 130026
The Meso-Cenozoic thrust-nappe tectonics in north part of the Qinling-Dabie orogen could be divided into five epochs,namely,Indosinian (T2-T3),Early Yanshanian (the last stage of J2-J3),Late Yanshanian (the last stage of K1),Terminal Yanshanian (the last stage of K2) and Early Himalayaian (the last stage of E) ones.The Meso-Cenozoic thrust-nappe tectonics in the area had an outstanding feature of space-time migration,which mainly embodied that the faults in the same epoch were obviously varied in scale and strength in varied regions and had a feature of diachronous migration evolution.The faults in varied epochs were clearly varied in scale,strength and geodynamic mechanism.The thrust-nappe tectonics in Indosinian epoch had a regularity of tectonic transport which was stronger in the east,weakened in the west,faulted in the east and folded in the west.The Early Yanshanian thrusting had a feature of diachronous migration evolution from the early period to the late period and from the east to the west.The Late and Terminal Yanshanian thrustings had tectonic feature which was weakened in the east and stronger in the west.The thrustings in the former four epochs were stronger in strength and larger in scale,but the scale and strength of thrust nappe tectonics in the Paleogene were weakened.The former three epochs had a tendency of progressive decreasing in scale and strength from the south to the north,but the latter two epochs were stronger in the north and weakened in the south,which showed that the Mesozoic orogeny had space time migration from the early period to the late period,from the east to the west,or from the south to the north.The Meso-Cenozoic thrust-nappe tectonics formed in a geodynamic background of diachronous collision between the Yangtze and the North China plates from the east to the west,and subduction and break-off of subducted plate in the intracontinent and mountains uplifting,extension and collapse.The formation mechanism of thrust tectonics in the Paleogene was supposed to be related to a far-field effect caused by collision between the Indian and the Eurasian plates.