Genesis of the Moghanlou Sb deposit (west of Zanjan): Evidences from geology, mineralization, geochemistry and fluid inclusions

Antimony mineralization at Moghanlou occurs as 2-3 meters siliceous-sulfide zone consisting of up to 10 centimeters wide quartz-stibnite breccia veins. The ore zone is hosted by amphibolite enclaves within feldspathic gr2 granite, and has N50E-trending that generally dips to the southeast at 75o. The hydrothermal alteration includes feldspathic, silicification, carbonatization and propylitic. The feldspar, quartz and carbonate alteration types are spatially associated with ore zone, whereas propylitic alteration affected amphibolite host rocks. Three stages of mineralization are distinguished at Moghanlou. Stage 1 is represented by silicification and carbonatization of host rocks along with minor disseminated pyrite. This stage is a pre-ore stage and it is usually crosscut by later stages. Breccia clasts of this stage have been recognized in the hydrothermal cements of stage 2 breccias. Stage 2 is the main ore-stage at the Moghanlou deposit. It is characterized by 2 to 10 cm wide quartz (calcite)-stibnite veins and breccias that usually cut stage 1 and, in turn, crosscut by stage 3 calcite veins. Stage 3 is a barren post-ore stage marked by calcite as vug infill and 1 cm wide veins. The ore minerals at Moghanlou are stibnite and minor pyrite. Stibiconite and goethite are the supergene assemblages, and the gangue minerals include quartz, calcite, actinolite, chlorite and talc. Ore minerals display disseminated, vein-veinlet, brecciated, comb, crustiform, cockade, plumose, vug infill and replacement textures.