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Crustal structure of the southern Dabie ultrahigh-pressure orogen and Yangtze foreland from deep seismic reflection profiling |
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| Authors: | Shuwen Dong Rui Gao Bolin Cong † Zhongyan Zhao Xiaochun Liu Sanzhong Li Qiusheng Li Dongding Huang |
| Institution: | Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China;;Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China;;Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;;College of Marine Geosciences, Ocean University of China, Qingdao 266003, China;;The 6th Geophysical Survey, New Star Petroleum Co., Sinopec, Nanjing 21000, China |
| Abstract: | A new 140‐km‐long seismic reflection profile provides a high‐resolution crustal‐scale image of the southern Dabieshan high‐pressure (HP) metamorphic belt and the Yangtze foreland fold‐and‐thrust belt. The seismic image of the stacked section shows that the southern Dabieshan metamorphic terrane and Yangtze foreland belt are separated by a large north‐dipping fault. In the foreland the upper crust is dominated by a series of folds and thrusts formed during the collisional stage in the mid‐Triassic; it was reworked by crustal extension resulting in the formation of a late Jurassic and Cretaceous red‐bed basin. The southern Dabieshan profile shows stacked crustal slabs developed along the margin of the collisional orogenic belt. The Moho reflectors at 10–11 s (～30–33 km) are seismically prominent and segmented by a number of south‐verging thrusts that were probably developed by foreland‐directed thrusting of the deeply subducted continental crust during exhumation. The seismic reflection profile suggests that structures related to the Triassic–Jurassic subduction and exhumation of the Yangtze plate are preserved despite the severe crustal extension superimposed during the late Mesozoic and Cenozoic. |
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