مينرالوگرافي و مطالعه ميكروپروب كاني هاي سولفيدي در كانسار چهل كوره زاهدان

Mineralography, and EPMA Study of Sulfide Minerals in Chehelkureh Ore Deposit, Zahedan, SE Iran

The Chehelkureh copper deposit is located in Kuh-e-Lunka area, about 120 km NW ofZahedan (SE Iran). The ore field extends lor 1500m in N23°W direction, and is displaced by late brittle faults, striking E-W roughly. The host rocks are Eocene intercalated turbiditic greywacke sandstones, siltstones. and shale (flysch). Several stocks and dykes of granodiorite to quartz monzodiorite and granite composition intruded the turbidites, homfelsing them locally. Primary mineralization occurred in two stages, and comprises quartz, dolomite, ankerite, siderite, calcite, and lesser amounts of pyrrhotite, arsenopyrite, pyrite, chalcopyrite, sphalerite, galena. Se-rich galena, marcasite, molybdenite, ilmenite. rutile. nevskite, and paraguanajuatite. According to drill holes, there is a reserve of copper, lead, and zinc, with an average of 1.48% Cu, 1.77% Zn, and 0.85% Pb (4.1% Cu+ Zn + Pb). Complex intergrowth textures, some of which represent exsolution textures, are common in ore minerals, indicating temperatures greater than 400°C for the formation of Chehelkureh are deposit. EPMA results of sulfides indicate the presences of Se, and Bi. The average content of Se is 0.01% in pyrite, 0.018% in sphalerite, 0.028% in chalcopyrite, 0.025% in pyrrhotite, and 0.015% in galena respectively. Besides Bi minerals, bismuth element is present sometimes in considerable amounts in sulfides. S/Se ratio in the Chehelkureh ore deposit is lower in galena, and higher in pyrite. These ratios, as a whole, show magmatic origin for mineralization.