Document Type : Original Research Paper
Authors
1 Ph.D. Student, Department of Geology, Ferdowsi University of Mashhad, Mashhad, Iran
2 M. Sc., Department of Geology, University of Tehran, Tehran, Iran
Abstract
Ahangaran is an active Pb-Ag mine of Iran that is located in Malayer town, Hamedan province and situated in the Esfahan-Malayer Pb-Zn Metallogenic Zone. The mineralographical studies of different parts of the Ahangaran mine show different sulfide-oxide zones with major minerals including galena, cerussite, chalcopyrite, magnetite, pyrite, hematite, goethite and others minor minerals. For the first time, the minor minerals including jordanite-lengenbachite series, coronadite and galena molybdate is identified as a host for Pb and Ag using scanning electron microscope (SEM) and electron probe micro-analyzer (EPMA). Freibergite (Fahlore group) and lanaite as two minor minerals containing Ag are reported as major element in the crystalline lattice, as well. In addition to Ag presence in the minor minerals, it is measured up to 500 ppm in galena and cerussite by EPMA studies. Pb isotope study on a galena sample from Ahangaran deposit shows the Pb is radiogenic with orogenic reservoir characteristics in which high amount of Pb originated from the upper and lower crust. In addition, Pb model age shows Pb derivation from Triassic basement (249 Ma), and Pb isotopic ratios suggest a mature arc environment for the Ahangaran deposit.
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