Micro thermometry of fluid inclusions on siliceous veins in Ramand area, south of Qazvin, Iran

Ramand area is located about 80 km south of Qazvin Province, northwest of Central Iran. The study area is a part of the magmatic belt of Orumieh-Dokhtar of the structural zones of Iran. The area consists of rhyodacitic igneous rocks, rhyolite, rhyodacitic tuff, crystalline tuffs and rhyodacitic flow lavas. The pyroclastic and volcanic units are interrupted by major faults such as Korcheshmeh and Hassanabad faults as well as sub-faults with a northwest-southeast trending. The most important alterations in the area includes sericitization, argilitization and hematization. The main ore minerals include pyrite, oxides and iron hydroxides. The most associated gangue minerals are quartz, potassium feldspar, albite and rock fragments in tuffs. In order to determine the properties of mineralizing fluids, fluid inclusions within quartz were analyzed, which are closely associated with gold mineralization in the area. The results of these analyzes show that the salinity of the fluids involved in the quartz minerals varies between 2 and 11.7 wt% NaCl equivalent. Also homogenization temperature of fluid inclusions for quartz varies between 141 and 230 0C. Most of the fluid inclusions in these veins are liquid double phase (L+V) and have sizes smaller than 20 micron. The analytical results of the analyzed samples show low temperature and salinity range which is consistence with metamorphism and basin brine sources. The fluid inclusions, mineralogical and geochemical data show that the gold mineralization in the Ramand area is similar to Epithermal type.