K-Ar dating of early cretaceous volcanic rocks along the Tan-Lu fault zone and its tectonics ignificance

The volcanic rocks from Longshan, Feidong in Anhui and Daotuo, Yishui in Shandong, along the Tan-Lu fault zone, were dated. The whole rock K-Ar ages of them was 119.2 plus/minus 2.3 Ma and 114.8 plus/minus 1.0 Ma respectively, which were obviously latter than the time of left-lateral slipp ing (143.3plus/minus 1.3 Ma) and coincident with the biotite 40Ar(-)39Ar ages (120~128Ma) from the intrusive rocks in Zhangbaling and zircons ages (106.9~121.4 Ma) from the granites in Feidong-Chaohu area. These ages implied that the Tan-Lu fault zone became, from a large-scale left-lateral slipping in early Early Cretaceous, an extensional one in late Early Cretaceous, and acted as a pathway of magmatic activities, which was related to regional lithospheric thinning in eastern North China Block.