Not all folds and thrusts in the Yangtze foreland thrust belt are related to the Dabie Orogen: Insights from Mesozoic deformation south of the Yangtze River
Not all folds and thrusts in the Yangtze foreland thrust belt are related to the Dabie Orogen: Insights from Mesozoic deformation south of the Yangtze River
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DOI：
10.1002/gj.1214
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发表时间：
2010-09
影响因子：
1.8
通讯作者：
S. Z. Li;Guochun Zhao;Guowei Zhang;Xin Liu;S. Dong;Yongbin Wang;Xiaoguang Liu;Y. Suo;L. Dai
中科院分区：
文献类型：
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作者：
S. Z. Li;Guochun Zhao;Guowei Zhang;Xin Liu;S. Dong;Yongbin Wang;Xiaoguang Liu;Y. Suo;L. Dai
扬子前陆褶皱冲断带位于中国中东部中生代大别碰撞造山带和中生代江南板内造山带之间。在长江以北大别造山带确认了3次区域性变形事件。最早的区域变形（D1）对应于华南板块向华北板块俯冲时发生的东南挤压。与晚二叠世—早三叠世蓝片岩相变质作用同时发生的由上至东南方向的剪切作用，可能与长江以北新元古代—古生代沉积盖层内大别杂岩和平斜坡式逆冲构造的区域性片麻质发育有关。主要韧性变形（D2）也以东南向倒转和平卧褶皱为特征，与高压岩石发掘的早期阶段一致。顶部至西南向逆冲和西西北向的开放褶皱属于单独的后期变形阶段D3。先前的40Ar-39Ar云母年代在245 - 205 Ma之间，表明D1 - D3事件发生在晚二叠世-早侏罗世。与这些变形相关的前陆褶皱和逆冲作用在大别造山带的东、西“分支”两侧，而在大别造山带的前部则不存在。与长江以北的变形相反，江南造山带新元古代-古生代沉积盖层的变形主要表现为三叠纪至侏罗纪的北缘褶皱和顶向北逆冲。根据长江南北地区变形和构造极性的差异，认为位于大别造山带正前方的长江前陆褶皱冲断带与大别造山带无关，而是由江南造山带形成的。版权所有©2010 John Wiley & Sons， Ltd
The Yangtze foreland fold‐and‐thrust belt is located between the Mesozoic Dabie collisional orogen and the Mesozoic Jiangnan intraplate orogen in east‐central China. Three regional deformation events are recognized in the Dabie Orogen north of the Yangtze River. The earliest regional deformation (D1) corresponded to a southeastward compression that occurred during the subduction of the South China Plate below the North China Plate. Top‐to‐the‐southeast shearing coeval with Late Permian–Early Triassic blueschist facies metamorphism, was possibly associated with the development of regional gneissosity in the Dabie complexes and flat‐ramp‐style thrusts within the Neoproterozoic–Palaeozoic sedimentary cover, north of the Yangtze River. The main ductile deformation (D2) is also characterized by southeast‐verging overturned and recumbent folds, coeval with the early stage of exhumation of the high‐pressure rocks. A top‐to‐the‐SW thrusting and WNW‐striking open folds belong to a separate, later deformation phase, D3. Previous 40Ar–39Ar mica dates ranging between 245 and 205 Ma suggest Late Permian–Early Jurassic ages for the D1 to D3 events. The foreland folds and thrusts related to these deformations in the Dabie Orogen flank the eastern and western ‘limbs’ of the Dabie Orogen but are absent in the front of it. In contrast to the deformation north of the Yangtze River, the deformation of Neoproterozoic–Palaeozoic sedimentary cover in the Jiangnan Orogen south of the Yangtze River is generally characterized by north‐verging folding and top‐to‐the‐north thrusting from Triassic to Jurassic times. Based on the differences of deformation and structural polarity between the south and north areas of the Yangtze River, we propose that the Yangtze foreland fold‐and‐thrust belt in the direct front of the Dabie Orogen is unrelated to the Dabie Orogen but resulted from the Jiangnan Orogen. Copyright © 2010 John Wiley & Sons, Ltd.