雪峰山、武陵山及其西北侧逆冲拆离构造与变形定量研究

Abstract In the Yangtze Block (South China), a well-developed Mesozoic thrust system extends through the Xuefeng and Wuling mountains in the southeast to the Sichuan basin in the northwest. The system comprises both.thin-skinned and thick-skinned thrust units separated by a boundary.detachment fault, the Dayin fault. To the northwest, the thin skinned belt is.characterized by either chevron anticlines and box synclines to the northwest,and chevron synclines to the southeast. The former structural style displays narrow exposures for the cores of anticlines and wider exposures for the cores of synclines. Thrust detachments occur along Silurian (Fs) and Lower Cambrian (Fc) strata and are dominantly associated with the anticlines. To the southeast, this style of deformation passes gradually into one characterized by chevron synclines, with associated principal detachment faults along Silurian (Fs), Cambrian (Fc) and Lower Sinian (Fz) strata. There are however,numerous secondary back thrusts. Therefore, the thin-skinned belt is not unlike the Valley and Ridge Province of the North American Applachian Mountains. The thick-skinned belt structurally overlies the thin skinned belt.and is characterized by a number of klippen including the Xuefeng and Wuling nappes. It is thus comparable to the Blue Ridge Province of Appalachia..The structural pattern of this thrust system in South China can be explained by a model involving detachment faulting along various stratigraphic.layers at different stages of its evolution. The system was developed through a northwest stepwise progression of deformation with the earliest delamination along Lower Sinian strata (Fz). Analyses of balanced geological cross-sections yield about 18.1-21% (total 88 km) shortening for the thin-skinned unit and at least this amount of shortening for the thick-skinned unit. The compressional deformation from southeast to northwest during late Jurassic to Cretaceous time occurred after the westward progressive collision of the Yangtze Block with the North China Block and suggests that the orogenic event was intracontinental in nature.Keywords: Balanced geological section; Thrust fault; Thin- and thick

厘定雪峰山、武陵山及其西北侧逆冲推覆构造格局，研究拆离构造几何学与运动学特征，查明不同构造层次的拆离构造特征及相关变形在三维空间的表现形式，系统测量褶皱、断裂和剪切带的几何参数和应变参数，编制平衡地质剖面，定量分析拆离构造的形成和演化过程，探讨其形成的动力学机制。为扬子板块中生代碰撞造山作用及盆山关系研究奠定基础。