关键词: 雪峰山, 中生代板内造山带, 断层相关褶皱, 穹隆状构造, 运动学模式

Abstract: One of the key scientific issues related to tectonics of the South China Block focuses on the nature of the JiangnanXuefeng orogenic belt. In this study, structural style and kinematics of five tectonic units, namely the Xiangzhong composite thrust belt, Xuefengshan thickskinned thrust belt, FanjingshanZouma domal belt, troughlike faultfold thrust belt and ejective thinskinned thrust belt, are identified along a geological crosssection of the Xuefeng orogenic belt with detailed profiles of regional geology, deformation and seismic interpretation. Our study shows: (1) The Xiangzhong composite thrust belt in the eastern Xuefeng orogenic belt is represented by the Longshan composite tectonic dome. This dome has structural style of the SEdipping thrust faultrelated Mesozoic chevron anticline, which overprinted the EWstriking Caledonian anticline. (2) The Xuefengshan thickskinned thrust belt is bordered by the Dayong thrust fault to the west, and outcrops extensively the shallow metamorphic Banxi Group. This belt has the NW faultrelated folds with smaller slip flatramp fault, where flat developed along the weak layers within the Banxi group while ramp cuts upward, thus producing the broad syncline and tight anticline, respectively. The flatramp fault also resulted in the Neoproterozoic Banxi Group thrusting over the Paleozoic, and the formation of the Yuanma Basin and klippes and tectonic windows. (3) The FanjingshanZouma domal belt is represented by the Fanjingshan tectonic dome. This dome has the structural style of faultrelated fold, with SEdipping flatramp thrust fault and hangingwall anisomerous box anticline, which outcrops the early Neoproterozoic Fanjingshan Group in the core. Thus the Fanjingshan tectonic dome was produced by thickskinned thrust. (4) The troughlike faultfold thrust belt contains a series of NEstriking parallel box anticlines and chevron synclines. The Cambrian outcrops in the core of the box anticlines while the SinianNeoproterozoic Banxi Group involves deep in the deformation. The fault developed imbricate faultrelated fold in the shallow and basement involved faultfold in the deep, making it an active duplex thrust fault. (5) The ejective thinskinned thrust belt, situated between the Huayingshan and Qiyueshan faults, is represented by chevron anticline and box syncline with SEdipping flatramp thrust fault produced by faultpropagation folding. All five tectonic units have deformations involving the Upper TriassicLower Jurassic and are unconformably covered by the Upper Cretaceous, indicating deformations occurred in the middlelate Mesozoic, and likely followed a “younging” trend from SE to NW. Therefore, this paper has proposed a new kinematic model, which contains essential features of the faultrelated folds, fold evolution, and the Mesozoic intraplate progressive orogeny along the Xuefeng Mountain.

Key words: Xuefeng Mountain, the Mesozoic intraplate orogenic belt, faultrelated fold, tectonic dome, kinematic model