Showing 1 results for Malayer-Esfahan Metallogenic Belt
Ebrahim Tale Fazel,
Volume 31, Issue 4 (12-2023)
Abstract
Investigation of geochemical-metallogenic conditions and mineralogy of the supergene, oxidation, mobilization, fractionation, and reprecipitation of metals, is fundamental for the understanding of the genesis of non-sulfide Pb-Zn deposits. The Changarzeh Pb-(Ag) deposit is located about 75 km northeast of Esfahan Province, within the southern Malayer-Esfahan metallogenic belt. Middle Triassic breccia-dolostone is the main mineralization host rock, and has two hypogene (sulfide) and supergene (oxide, carbonate, and silicate) ores. Frequent minerals of the supergene ore include smithsonite, hemimorphite, hydrozincite, anglesite, and cerussite. Metal separation is caused by a gradual changes from an acidic oxidation zone to alkaline conditions in the adjacent carbonate wall rock. The formation of an acidic oxidation zone within carbonate host rocks is facilitated by the “armouring” of galena by anglesite and by several pH-buffering reactions. The high activity of sulfuric acid-related SO42- ions during the oxidation stage led to the precipitation of highly insoluble anglesite, which results in low Pb2+ concentration within the fluid. Generally, limited availability of meteoric water and deep-water tables protect the non-sulfide ore from subsequent dissolution, where these conditions played an important role in the understanding on trcaing of non-sulfide supergene deposits.