论文部分内容阅读
现今出露在北大别穹隆北界上的晓天—磨子潭韧性剪切带是早白垩世造山后伸展活动的产物。野外观测、室内石英C轴组构与运动学涡度测量指示,这一NWW—SEE走向、倾向NNE的韧性剪切带,呈现为正左旋走滑运动,以简单剪切变形为主。该剪切带内现今所保留运动学特征及其在空间上的变化反映其形成后经历过旋转改造。以实测组构为约束的变形模拟揭示,该剪切带在早期伸展活动时为中地壳内上盘向280°方位运动的水平韧性剪切带,后在北大别穹隆上拱中被动地抬升而成为现今状态。北大别穹隆西强东弱的上隆幅度是晓天—磨子潭韧性剪切带被不均匀抬升和旋转的主要原因。该剪切带与北大别穹隆皆为早白垩世造山后重力垮塌中形成的,具有科迪勒拉型变质核杂岩特征。
The Xiaotian-Mozi Tan ductile shear zone now exposed on the northern boundary of the Northern Dabie Forth is the product of post-Early Cretaceous orogeny. Field observations, indoor quartz C-axis configuration and kinematic vorticity measurements indicate that this NWW-SEE ductile shear zone, which is prone to NNE, presents a positive-left-lateral strike-slip movement dominated by simple shear deformation. The kinematic features now retained in this shear band and their spatial variations reflect the rotational transformation that has occurred since their formation. The deformation simulation constrained by the measured tectonics reveals that the shear zone is a horizontal ductile shear zone moving towards the 280 ° azimuth in the mid-crust at early extensional activity and is then passively raised in the arch of the North Dabie Fold Become the present state. Uplift of the Xijiang-Dongbei weakening of the North Dabie Fold is the main cause of uneven uplift and rotation of the Xiaotian-Mozi Tan ductile shear zone. The shear zone and the North Dabie Fold were formed during the Early Cretaceous orogeny after gravity collapse and have the characteristics of Cordillera-type metamorphic core complex.