关键词: 马鬃山地区, 早古生代, 韧性剪切带, 年代学

Abstract: The Yemaquan-Lebaquan ductile Shear Zone, as the result of microcontinent collision in the Beishan Orogen, is of great geological significance in the Early Paleozoic collision-orogenic process of the Beishan orogenic belt. Previous studies mainly focused on the tectonic metamorphic core complex and the ophiolite in Lebaquan area. In order to better constrain its active age, the structural profile and microstructural characteristics of the Lepaquan-Yemaquan ductile shear zone were studied. It shows that the shear zone thrust from NWW to SEE during the earlier period, which then transformed into nearly E-W dextral strike-slip during the late stage. The mylonite zone was intruded by the late undeformed granite veins, which have a zircon U-Pb age of 416 Ma. Integrated with the previous studies, the time ductile deformationwas constrained between 423-416 Ma.

Key words: Mazhongshan, Early Paleozoic, ductile shear zone, chronology