Geological setting of iron oxide-apatite deposits in theBafq ‎district, central Iran with an emphasis on mineralogical,petrographic, and geochemical study of the Sechahun deposit

The objective of this research is to determine all processes in the magmatic evolution and related hydrothermal activities that created the volcanic rocks and associated ore-forming systems of the Bafq ýmining district. Several iron oxide-apatite (IOA) deposits were investigated in this area with a focus on the Sechahun ore deposit. The Bafq ýmining district is well known for hosting significant IOA ore deposits with several million tons of iron ore and with some economic resources of rare earth elements. To achieve the goals of this research, detailed petrographic, fluid inclusion microthermometry, and lithogeochemical studies were obtained and supported by geological investigations at both local and regional scales. Textural, mineralogical, and fluid inclusion evidence indicates the ore genesis by fluid mixing. Magmatic-hydrothermal iron oxide-apatite ore precipitated during circulation of deuteric solutions within the host rocks at the early stage of mineralization. The mesothermal iron oxide ore of the Sechahun deposit was emplaced at the relatively shallow depths, while the near-surface epithermal hematite-jaspilite ore formed in a subaqueous environment. The most likely source of iron oxide-apatite mineralization would be a combined magmatic hydrothermal to convective hydrothermal model ýwith magmatism originating from the upper mantle and related bimodal volcanism resulting in felsic volcanic rocks. Rifting of the continental lithosphere during the Early Cambrian was associated with emplacement of a highly fractionated bimodal ýmagmas along the regional ýfracture-fault lines, a major controlling factor for mineralization processes in the Bafq district. ý