Authors
1
1- MSc. student, Department of Geology, Faculty of Science, Bu-Ali Sina University, Shahid Fahmideh Street, 65174-4161, Hamedan, Iran.
2
Bu-Ali Sina University
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3- Assistant Professor, Department of Geology, Faculty of Science, Bu-Ali Sina University, Shahid Fahmideh Street, 65174-4161, Hamedan, Iran
4
4- MSc., Department of Geology, Faculty of Sciences, Birjand University,South Khorasan, Iran.
Abstract
The Pirhajat deposit is 5 km northeast of Pirhajat, 120 km northwest of Tabas in the Pirhajat mountain range. This deposit is in the Central Iranian subcontinent and the Tabas-Poshtbadam metallogenical province in Uzbakkoh-Eshghabad section. The geological units of the region include two carbonate rock units (dolostone and dolomitic limestone) belonging to the Middle Triassic Shotori Formation and the sandstone of the Lower Jurassic Shemshak Formation. On the basis of K2O/Na2O versus SiO2/Al2O3 diagram, the sandstone unit with lith-arenite lithology is plotted in the passive continental margin area. The mineralization in this deposit is strongly controlled by tectonic processes in which the main fault is the most important, with an east-west strike-slip extension and a slope of 70-80 degrees to the south. The mineralization occurred in two hypogene stages including native lead, galena, pyrite, tetrahedrite, chalcopyrite, and sphalerite, and a supergene stage includes lead oxide minerals (plattnerite, massicot-minium), linarite, anglesite, cuprite, malachite, azurite, chrysocolla, covellite, tenorite, goethite, cerusite and gangue minerals consist of barite, quartz, calcite and dolomite. The main mineable metal that can be extracted in this deposit is lead as native lead, plattnerite (lead oxide) and to a lesser extent lead sulfide (galena). On the basis of the results of ICP-OES analysis (13 samples), lead has an average grade of 3% and the maximum silver in this deposit is 27 ppm, which shows the relatively high grade of lead and the presence of silver, that show a promising economic outlook. Also, zinc has an average grade of 372 ppm (in 13 samples). Copper also has a grade of more than 5% in some samples. On the basis of these studies and analyses,
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