~(40)Ar-~(39)Ar phlogopite dating of large skarn Fe deposits and tectonic framework in southeastern Hubei Province,Middle-Lower Reaches of the Yangtze River,eastern China

The Cu,Fe polymetallic deposits in southeastern Hubei are an important component of the Middle-Lower Yangtze River metallogenic belt,but the timing and tectonic framework of these deposits were poorly constrained.In this paper we present new 40Ar- ~(39)Ar phlogopite ages for the Chengchao and Jinshandian skarn iron deposits to constrain the timing and duration of mineralization. Phlogopite from the Chengchao and Jinshandian skarn deposits yielded a ~(40)Ar-~(39)Ar pleatu ages of 132.6±1.4Ma and 131.6±1.2 Ma respectively,and isochronal ages of 136±4 Ma and 132.0±2.8 Ma respectively.Integrated mineral paragenesis and fluid inclusion, we concluded that the~(40)Ar-~(39)Ar system in phlogopite remain to be closed with ore deposition,and constrain the formation of the Chengchao and Jinshandian skarn iron deposits at 132.6±1.4Ma and 131.6±1.2 Ma,respectively.These results are coincident with the Daye skarn Fe deposit and(porphyry)-skarn Cu deposits in southeastern Hubei Province.An integrated study of available petrological and geochemical and geophysics evidences,we concluded that the skarn Fe mineralization in southeastern Hubei was associated with lithospheric extension and thinning during the Late Mesozoic in Eastern China.