Calcite U-Pb Dating and Micro-XRF Analysis Constraint on Formation of Bawang Zn-Fe-Sn Deposit in Danchi Metallogenic Belt,South China
Danchi metallogenic belt is one of the most important nonferrous metal industry bases.It is to be the research focus owing to the large scale of Sn and Sb metal budget.The genesis of Sn-polymetallic mineralization during the Late Cretaceous and the relationship between Zn-Sn and Sb mineralization in the belt remain unclear.The Bawang deposit,a recently discovered paleokarst infilled type deposit,occurs in the west limb of the Wuxu anticline.Basing on the earlier study of structural analysis,mineralogy,and cassiterite U-Pb ages,in this study it presents element mapping of ores by micro-XRF(μ-XRF)analysis,and in situ U-Pb laser ablation-magnetic sectorfield-inductively coupled plasma mass spectrometer(LA-SF-ICP-MS)ages of calcite during the antimony mineralization stage.Micro-XRF analysis revealed that the sphalerite,cassiterite-quartz,and arsenopyrite mineralization have taken place in order in the Bawang deposit.Calcite U-Pb dating provides a lower intercept ages of 62.8±1.1 Ma(MSWD=2.6;2σ).Combined with previous ages of Zn-Sn mineralization,mineralogy,and μ-XRF analysis,the Zn-Sn mineralization is 30 Ma earlier than Sb mineralization.The pressure contrast existed between the fluid pressure at the site of ore deposition and the fluid pressure within the concealed intrusion is the key dynamics of fluid flow for the tin mineralization.
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