Mineralogy and Geochemistry of Ores of the Kedrovskoe–Irokinda Ore Field (Northern Transbaikalia)

Abstract

Abstract —Ore mineralogy of the Kedrovskoe–Irokinda ore field (northern Transbaikalia) has been studied. The ore field comprises ca. 200 quartz veins. Vein 3 and the Kvartsevaya and Serebryakovskaya veins of the Irokinda deposit and the Shamanovskaya, Pineginskaya, Osinovaya, and Barguzinskaya veins of the Kedrovskoe deposit have been described. Quartz–pyrite assemblage (quartz-1, pyrite, pyrrhotite, and marcasite) and quartz–gold–sulfide assemblage (quartz-2, galena, chalcopyrite, sphalerite, electrum, fahlore, Ag tellurides, and sulfosalts of Ag, Cu, Sb, Pb, and Sn) have been revealed. Major ore minerals were investigated by EPMA and LA-ICP-MS. An increase in Ag content in electrum (from 5.5 to 72.4 wt.%) and fahlores (from 5 to 35 wt.%) and in the abundance of Ag minerals during the ore formation has been established. Galena contains impurities of Sb and Ag (thousands of ppm), Se, Cd, Te, and Bi (hundreds of ppm), Cu, Zn, As, and Sn (tens of ppm). It is shown that the Kedrovskoe–Irokinda ore field is a rare type of orogenic deposits with considerable variations in the composition of major ore minerals (electrum, sphalerite, and fahlores), which is explained by the diversity of the host rocks.