Mineralogy and geochemistry of Siriz iron deposit, northwest of Zarand, Kerman province

Siriz iron deposit is located in Central Iran structural zone, 75 km northwest of Zarand, Kerman Province. Iron mineralization occurred mainly as irregular ore bodies, lenses and veins in Paleozoic metamorphosed dolomitic limestone known as Kuhbanan Formation and the skarn units at the contacts of Siriz granitoid pluton. The Siriz iron deposit shows a simple mineralogical composition including magnetite, pyrite, chalcopyrite, hematite and iron hydroxides. The Siriz granitoid pluton is composed of quartz syenite, quartz monzonite, syenite and syenogabbro, with a calc–alkaline origin. Based on geochemical studies and classification, this pluton shows A-type characteristics with A1 subclass, originated from a mantle source. The Siriz skarn mineralization system consists of Siriz granitoid pluton as heat and mineralization source, skarn zone, massive magnetite iron ore lenses and veins, and metamorphosed dolomitic limestone (marble). An advance contact metamorphism between Siriz pluton and the dolomitic limestone of Kuhbanan Formation originated a calcic marble with granoblastic texture with garnet-wollastonitemarble (calcite) assemblage in limestone and garnet-clinopyroxene-phlogopite assemblage in dolomitic limestone. The Ca(-Mg) silicate minerals formed at this stage are mainly anhydrous and are not associated with iron mineralization. The peripheral high temperature magmatic-hydrothermal system changed to lower temperature system during the progressive cooling of the Siriz granitoid pluton,. This stage was recognized by formation of epidote, tremolite–actinolite, biotite, muscovite, chlorite, talc, calcite and quartz mineral assemblage in the Siriz iron deposit skarn unit. The association of iron mineralization and the late retrograde mineral assemblages, suggests that the iron mineralization is probably related to the fluid mixing with cooler meteoric water and decline in ore fluid temperature.