Intermediat-sulfidation epithermal Cu (Pb and Zn) mineralization in the Marshoun 2 occurrence (SE Zanjan): Mineralization, geochemistry and fluid inclusions evidences

Mineralization in the Marshoun 2 occurrence occurs as quartz-sulfide veins hosted by intermediate tuff units, and is divided into four stages. Stage 1 is represented by silicification of host rocks along with minor disseminated pyrite. Stage 2 is characterized by quartz-sulfide (chalcopyrite, pyrite) veins and breccia cements. Stage 3 is characterized by quartz (calcite)-sphalerite-galena ± chalcopyrite ± pyrite veins and breccia cements. Stage 4 is barren post-ore quartz-calcite vein-veinlets. The hydrothermal alteration includes of silicification, intermediate argillic, carbonate, and propylitic alteration. The ore minerals are pyrite, chalcopyrite, galena, and sphalerite; quartz, sericite, chlorite and calcite are present as gangue minerals. Ore minerals display vein-veinlet, brecciated, comb, crustiform, colloform, cockade, plumose, bladed, skeletal, and vug infill textures. Similar Chondrite–normalized rare elements and REE patterns of mineralized samples indicate that hey may have fomed by same hydrothermal process. Microthermometric data reveal that ore-forming fluids at the Marshoun deposit belong to the moderate-temperature and low-salinity H2O–NaCl system. Fluid boiling and mixing were important processes in the evolution of the ore-forming fluids. Marshoun 2 is an intermediate-sulfidation epithermal deposit.