Cathodoluminescence, micro thermometry and laser raman spectroscopy studies on hydrothermal quartz in Latala deposit, Central Iran

The Latala base and precious metals deposit is hosted by quartz veins, associated with a porphyry pluton intruded into a Cenozoic volcanic sequence. Euhedral quartz with sulfide mineralization such as pyrite, chalcopyrite, galena and sphalerite, with minor sulfosalts occurs in these veins as open space fillings and minor replacement bodies. Progressive growth of quartz crystals is evidenced by their texture revealed by cathodoluminescence imaging. The analysis of fluid inclusions indicate a decreasing homogenization temperature from 350°C in the core to 135°C along the edge of the quartz crystals with overgrowths. The presence of CO2 vapor suggested by the thermometric analysis is confirmed by Raman spectrometry. The solid phases in fluid inclusions identified as phyllosilicates, presumably muscovite and illite, chlorite, quartz and carbonate-mineral such as (Natrocarbonate, Dawsonite) by petrography and Raman spectrometry. Solid phase of halite were identified in two fluid inclusions. The homogenization temperature and salinity varies between 131 to 380 °C and 0.17 to 7.7 wt.% NaCl eq respectively. The properties of fluid inclusions corresponds to a magmatic hydrothermal fluid circulating from depth to shallower environments. The sulfur isotopic composition for galena, sphalerite, chalcopyrite and pyrite varies between -9.8 and -1‰, which correspond to values of magmatic sulfur. The δ34S values from .8 to -9.2‰ are in the range of hydrothermal fluids. Fluid inclusions features show a magmatic hydrothermal source which transported magmatic fluid and vapor from the depth through fractures to shallow environment. It suggests that magmatic water mixing with meteoric water was responsible for transportation of metals in Latala. Epithermal mineral precipitation during boiling, mixing and water-rock interaction formed hydrothermal quartz and sulfide mineralization. The available evidence suggests that the hydrothermal fluids changed from magmatic to epithermal in the region.