Место издания:Université de Lorraine Nancy, France
Первая страница:255
Последняя страница:258
Аннотация:Copper-molybdenum-gold porphyry deposits and occurrences of the Baimka trend located 250 km South of Bilibino, Chukchi Peninsula, Russia are spatially related to monzonitic rocks of the Early Cretaceous Egdykgich Complex. Four precious metal-bearing mineral assemblages were identified within this trend: (1) bornite + chalcopyrite + quartz with inclusions of high fineness gold in bornite, (2) Mn-poor dolomite + quartz + sulfides (sphalerite, galena, chalcopyrite, tennantite-tetrahedrite) ± tourmaline with medium-fineness gold, (3) rhodochrosite + Mn-rich dolomite + quartz + sulfides (sphalerite, galena, chalcopyrite, tennantite-tetrahedrite) with low-fineness gold, electrum, acanthite, and Ag and Au-Ag tellurides, and (4) calcite + quartz + sulfides (sphalerite, galena, chalcopyrite) with low-fineness gold, Ag sulfides and selenides, Ag-bearing sulfosalts, and acanthite. On the basis of geochemical study, the AgPbZn/CuBiMo is suggested as an index of erosion level of porphyry-epithermal system: the higher this index the shallower erosion level. The erosion level of deposits and prospects in the Nakhodka ore field located within the Baimka trend increase from Vesenny deposit through Pryamoi and Nakhodka prospects to the III Vesenny procpect.