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Fig. 14. Bulk continental crust-normalized multi-element spider diagrams for the VMS-type, skarn-type, and the Dingjiashan and Fengyan magnetite (Rudnick and Gao, 2003). Data sources VMS deposits are from Makvandi et al. (2016); skarn deposits are from Zhao and Zhou (2015), Hu et al. (2017), Ding et al. (2018), Li et al. (2018), Yi (2018), Li et al. (2019), Chen et al. (2020), Chen et al. (2021), Dong et al. (2021), and Peng et al. (2021). [Display omitted] • Magnetite geochemistry can be used to distinguish VMS and Zn-Pb skarn type deposits. • VMS-hosted magnetite has higher V but lower Mn contents than skarn-hosted magnetite. • Dingjiashan and Fengyan magnetite are skarn-type rather than VMS-type. Central Fujian is an important polymetallic (Zn-Pb-Ag-Cu-Mo-Au) mineral province in southeastern (SE) China, yet its mineralization is still disputed between Proterozoic volcanogenic massive sulfide (VMS) or Mesozoic skarn-type. The Dingjiashan and Fengyan are two representative of them, with the ores mainly hosted in the Meso-Neoproterozoic Longbeixi Formation marble and schists. For the magnetite from Dingjiashan and Fengyan, their hydrothermal mineral assemblage and their low V, Al, Cr, Ni, Ga, and HFSEs contents (cf. igneous magnetite) are all typical of hydrothermal origin. LA-ICP-MS time-resolved depth profile and inter-element correlation suggest that: 1) Mn, Ti, V, Ni, and Cr are mainly present in solid solution; 2) Na, Mg, Al, K, Si, and Ca occur both as solid solution and the micro-silicate inclusions and/or halite-bearing fluid inclusions; and 3) Zn, Co, Cu, Ag, Pb, and Bi are intimately associated with sulfide micro-inclusions. For both Dingjiashan and Fengyan magnetite, the Ti, V, Al, Ga, and Mn contents are temperature-controlled, whilst Ti, V, Cr, and Sn contents are redox-controlled. Meanwhile, the Ca and Mg contents are controlled by fluid-rock interactions, and the Mn enrichment is inherited from the fluid composition. Coexisting mineral phases have likely exerted major geochemical control on the magnetite samples. We compiled a large published geochemical dataset on magnetite from well-studied VMS and skarn deposits worldwide. Compared with VMS-hosted magnetite, skarn-hosted magnetite has relatively high median contents for Ca, Al, Ge, Sn, Mn, and Mg, and low median contents for Si, Ga, Ti, V, Ni, and Cr. Overall, the Dingjiashan and Fengyan magnetite samples have similar trace element compositions (esp. Mn and V) to those of skarn-hosted (rather than VMS-hosted) magnetite. Magnetite geochemistry thus suggests that both the Dingjiashan and Fengyan are best classified as stratabound, distal Zn-Pb skarn deposits. Our findings highlight the effectiveness of magnetite trace element geochemistry in differentiating ore deposit types, which contributes to regional Zn-Pb ore exploration and research. [ABSTRACT FROM AUTHOR]

• A global geochemical dataset of VMS- and skarn-hosted sphalerite was compiled and reviewed. • VMS-hosted sphalerite has broader trace element range than its skarn-hosted equivalent. • VMS-hosted sphalerite has higher Fe-Ag but lower Mn-Co contents than skarn-hosted sphalerite. • Sphalerite trace element geochemistry can be a useful exploration and research tool. Central Fujian is an important polymetallic (Zn-Pb-Ag-Cu-Mo-Au) mineral province in southeastern China, yet its mineralization is still disputed with proposed genetic models ranging from Proterozoic volcanogenic massive sulfide (VMS) to Mesozoic skarn-type mineralization. The Fengyan stratabound Zn-Pb deposit is mainly hosted in marble of the Meso-Neoproterozoic Longbeixi Formation. The deposit contains two types of ore-stage sphalerite (Ⅰ and II) distinguishable based on their paragenetic relations and associated mineral assemblages. Sphalerite I generally occurs as solitary crystals characterized by black to red internal reflections. Sphalerite II is commonly associated with galena and chalcopyrite, and has yellow internal reflections. Sphalerite I has lower concentrations of Co, Cd, Cu, Pb, Ag, and Bi, but higher concentrations of Fe, Mn, and In compared to sphalerite II. Both sphalerite types have very low contents of Ga, Ge, and Sn. According to a large, global sphalerite geochemical database of well-studied VMS and skarn deposits compiled as part of this study, skarn-hosted sphalerite is characterized not only by a broader range of contained trace element contents than its VMS-hosted equivalent but also by higher concentrations of Fe, Ga, Ge, and Ag and lower Mn, Cd, In, and Co. Trace element geochemistry and metal concentrations can thus be used to distinguish VMS and skarn deposits. Overall, the two sphalerite types from Fengyan have similar trace element compositions to those of skarn-hosted (but not VMS-hosted) sphalerite. In addition, the two types of sphalerite and their coexisting minerals have a narrow in-situ δ34S range (-1.6 to 4.1 ‰, mean 2.3 ‰), indicating a magmatic source. The elemental and isotopic geochemical evidence suggests that Fengyan is best classified as a stratabound, distal Zn-Pb skarn deposit. Our work highlights the effectiveness of sphalerite trace element geochemistry for differentiating ore deposit types, thereby presenting a possible tool in support of both Zn-Pb ore exploration and research. [ABSTRACT FROM AUTHOR]