عنوان مقاله English
نویسنده English
Mehdi Abad copper deposit is located in 160 km northeast of Birjand, in South Khorasan province and in the Tertiary volcanic zone of the Lut Block. The major rock units of the study area have Eocene age and include andesitic lavas (andesite, trachyandesite, and pyroxene andesite), pyroclastic units (agglomerate and tuff) with jasper veins. Copper mineralization in this region is epigenetic along lava and pyroclastic units with andesitic composition along with tuff. The main ore textures include vein- veinlets, open space filling, disseminated and replacement. The ores contain primary minerals chalcocite, bornite, chalcopyrite and pyrite and the secondary minerals covellite, secondary chalcocite, cuprite, malachite, azurite, chrysocolla, hematite, goethite and limonite. The most important alterations accompanied with mineralization include carbonatic-silicic, argillic, chloritic, and Fe-oxide alterations that the amount of carbonatic-silicic alteration increases with closing to mineralization zones. Disequilibrium textures such as chemical zoning, sieve texture, rounded and gulf shape margins observed in phenocrysts of these rocks. Geochemical studies results show that these lavas belong to high to medium-K calc-alkaline series. Enrichment in LILE and LREE, depletion in HFSE and HREE in these rocks suggests active continental margin volcanic arc magmatism. Based on tectonic discrimination diagrams, Mehdi Abad area lavas are related to subduction zone and active continental margin that has been contaminated with crustal material while ascending to the surface. In this area, copper-rich magma has impacted the earth's surface while ascending from the subduction zone, creating a set of volcanic rocks with an intermediate composition in the form of lava and pyroclastics on the earth's surface, which are host rocks for copper mineralization.
کلیدواژهها English
