Synorogenic movement of the Tan-Lu fault zone
ZHU Guang, WANG Yong-sheng, NIU Man-lan, LIU Guo-sheng, XIE Cheng-long(College of Resource and Environment Engineering, Hefei Universityof Technology, Hefei 230009, China)
The origin timing and the model of the Tan-Lu fault are still debatable. It was found recently on the eastern margin of Dabie Mountains that the earlier sinistral strike-slip ductile shear belts exist in the Tan-Lu sinistral strike-slip ductile shear zone of the Early Cretaceous. Muscovite samples of mylonite from three localities in the earlier shear belts yield~(40)Ar/~(39)Ar plateau ages of (188.7±0.7) Ma, (189.7±0.6) Ma and (192.5±0.7) Ma, respectively. This dating indicates a synorogenic strike-slip thermal event. The foreland sediments and structures also show the activity of the fault zone during the collision of the North and South China plates. The synorogenic structures in the fault zone as well as the peripheral foreland sediments and structures demonstrate that the synorogenic motion of the fault zone was of a transform fault type, which sinistrally offset the Dabie and Sulu orogens for ca. 350 km and caused the anti-clockwise rotation of the Sulu orogen. During the activity of the fault zone in the Early Cretaceous, it extended further north and had left-lateral displacement of ca. 200 km. Therefore, the Tan-Lu fault was derived from the collision of the North and South China plates. Its synorogenic movement was associated with the continent-continent collision process of the two plates.