پترولوژی (Nov 2018)
Mineralogy, geochemistry and fluid inclusion studies of Dagh-Dali Zn-Pb(±Au) Deposit, Northern Takab, Northwest Iran
Abstract
Dagh-Dali Zn-Pb deposit is located 40 km north of Takab city and it consist of Bekhair-Bolaghi and Baldirghani ore zones. Mineralization in Bekhair-Bolaghi is consist of galena, sphalerite, pyrite and chalcopyrite with disseminated texture hosted in the Kahar shales and Jangotaran dolomitized limestone. Sphalerite is mainly associated with galena or surrounded by pyrite. Galena is formed in two forms of disseminated and fine crystalline texture in association with chalcopyrite and massive texture in association with sphalerite. Stibnite is associated with galena and sphalerite, and chalcopyrite is the least frequent sulfide minerals in the deposit. Gold scan study shows a insignificant concentration of gold in pyrite structure. In Baldirghani, As-Sb-Au mineralization occurred in marl, sandstone and tuff of the Qom Formation. Realgar and orpiment with mosaic, stibnite with radial and spheroidal, barite with fibrous and sphalerite with spheroidal textures are hosted in quartz vein. There is trace of gold in realgar and stibnite structure based on gold scan study. Based on geochemical investigation in Bekhair-Bolaghi, Pb-Zn, Pb-Ag, Zn-Sb, Ag-Sb and Pb-Sb pairs and in Baldirghani, Pb-Zn and Pb-Ag pairs have strong positive correlation. Exploration drilling results indicate that mineralization is shallow(<30m). Fluid inclusion analyses indicate that ore bearing fluid salinity is 4.55 to 6.81 wt% NaCl eq. with mean temperature 212.5°C for Bekhair-Bolaghi and 1.65 to 10.48 wt% NaCl eq. with temperatures 170 to 207°C for Baldirghani. Based on geological, mineralogical, geochemical and fluid inclusion studies, it seems that Dagh-Dali Zn-Pb deposit is similar to low sulfidation type deposits.
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