A NEW TYPE OF GOLD-SILVER MINERALIZATION IN NORTHEAST RUSSIA

Abstract

Based on numerous empirical data, it has long been accepted in geological literature that volcanogenic or epithermal deposits do not grade into mesothermal or plutonogenic ones in deeper zones. The grading is usually difficult to recognize during the study of epithermal deposits. On the contrary, Izava @et al.@ [1] discovered a second stage of very rich epithermal mineralization beneath the volcanogenic unit in terrigenous basement rocks of the Khisikari deposit (Japan). We identified a telescoped superposition of different mineralizations in the Sopka Rudnaya gold--silver deposit (Central Chukotka) [2]. In addition to two stages of epithermal ores confined to terrigenous basement rocks and volcanogenic sequences, low-grade (pyrite--arsenopyrite) mineralization zones with fine-dispersed gold were recovered by boreholes in terrigenous sequences at a depth of 100--200 m along the dip of epithermal veins. We believe that fine-disseminated gold--sulfide ore bodies and gold--silver deposits of Central Chukotka make up a single ore-association series. Moreover, the gold--sulfide ore bodies can be considered root zones of epithermal ore fields within a single ore-forming system [3]. According to Kalinin @et al.@ [4], the Carlin-type disseminated gold--sulfide mineralization can be expected in carbonate basement rocks of the epithermal Ol'chan ore field (Omolon terrane).