The Feidong ductile shear belt in the Tan-Lu fault zone is geometrically a sinistral stike-slip fault of a flower pattern. The mylonite and ultramylonite in the ductile shear zones yield whole-rock 40Ar/39Ar ages of 120. 48 Ma and 118. 75 Ma respectively, which suggest that large-scale sinistral displacement in the Tan-Lu fault zone took place in the Early Cretaceous. Studies on deformation and overprinting structures in the belt demonstrate that the Fuchashan area of Feidong is a relict block of the Indosinian Dabie-Jiaonan orogenic belt, which has been transected, dragged, overprinted and reworked by the Tan-Lu fault zone. The Tan-Lu fault zone and the Dabie-Jiaonan orogenic belt were developed in different times and belong to different tectonic systems. The former belongs to the circum-Pacific system while the latter is part of the Tethys system.