Cenozoic collisional tectonics and origin of Pb-Zn-F mineralization in the Bitlis Massif, SE Turkey

Abstract

Hasbey Pb-Zn-F mineralization in the Bitlis Massif, south of Lake Van, lies within the Neotethyan suture of the Alpine orogenic belt. Mineralization occurs in two different lithologies and locations: Type-I is present in dolostone fractures and faults as veins and veinlets, whereas Type-II occupies a fault zone between black marbles and calcschists. Sphalerite and argentiferous galena are the main ore minerals in both types. The dominant gangue minerals are quartz and dolomite in Type-I ore and calcite, quartz, and green-white fluorite in Type-II. Analysed fluid inclusion data from sphalerite, fluorite, and quartz indicate that high-temperature (>500 degrees C) mineralization was initiated from low-salinity fluids (4.3 wt.% NaCl equiv.). As temperatures dropped from 400 degrees C to 160 degrees C, the salinity of solutions increased and appreciable CO2 was contributed to the fluid system. In the absence of immiscibility, assemblages of fluid inclusions containing CO2 indicate that the solutions were homogeneous during entrapment and that mineralization took place under pressure conditions between 5 and 2 kb.