Geochronology of Diagenesis and Mineralization of the Luoyang Iron Deposit in Zhangping City,Fujian Province and Its Geological Significance

In order to determine the main mineralization time and ore forming genesis in the southwestern Fujian Province,this paper selects the Luoyang iron deposit to develop the study of LA-ICP-MS zircon U-Pb isotopic dating for granite and Re-Os geochronology for molybdenite from the iron ore body.According to the results,the molybdenite Re-Os isotopic model date is(133.0±1.9)to(134.0±4.2)Ma,which belongs to Early Cretaceous;and LA-ICP-MS zircon U-Pb isotopic dates for the granite porphyry and fine grain porphyritic granite are(131±1)Ma and(131.64±0.62)Ma respectively,which is very close to the mineralization time achieved by the Re-Os isotopic dating.According to the analysis of the granites,spatial distribution of magnetite and molybdenite ore bodies,and the mineralization and alteration characteristics,combining with the above granite and deposit chronological data,it is suggested that the Luoyang iron deposit mainly formed at Early Cretaceous when the contact thermofluid metasomatism occurred between the Early Cretaceous granites and the Carboniferous clastic and carbonate strata.