Geology, Mineralogy and fluid inclusion studies of the Abdossamadi barite deposit, northeast Marivand

Abdossamadi barite deposit is located 80 km northeast of the city of Marivan in the northwestern part of the Sanandaj–Sirjan metamorphic zone. The rocks in the deposit area predominantly consist of Cretaceous volcanosedimentary sequences of metamorphosed andesite, calcareous shale and limestone, metamorphosed under greenschist facies grade. The deposit is composed of stratiform ore and stringer zone. The stratiform ore consists of a lens-like barite body associated with sulfide minerals which are underlain by metamorphosed (and altered) andesite (stringer zone) and was under the calcareous shale. Sulfide mineral assemblages of the deposit are simple and consist of pyrite, sphalerite, galena, chalcopyrite, and tetrahedrite-tennantite. Massive, bedded, colloform, framboidal and disseminated structures and textures are common in the stratiform ore and indicate deposition of the deposit on the sea floor. The stringer zone that forming footwall of the stratiform ore is altered andesite that cut by sulfide-bearing quartz-barite veins and veinlets. Fluid inclusion studies indicated that barite samples in the stratiform ore homogenized between 115° and 215°C. Salinities of the fluid inclusions show a range from 0.21 to 5.86 wt.% NaCl equivalent. Cooling of the ore-bearing hydrothermal fluid is an important process in the stratiform ore deposition. This study shows that the barite deposit is an immature Kuroko type massive sulfide deposit, which contains only black ore. The deposit underwent metamorphism and deformation after the ore deposition and therefore, shows significant changes in ore structures and textures.