Gold–Silver Mineralization in Porphyry–Epithermal Systems of the Baimka Trend, Western Chukchi Peninsula, Russiaстатья
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Дата последнего поиска статьи во внешних источниках: 2 ноября 2016 г.
Аннотация:—Mineralogical, fluid inclusion, and geochemical studies of precious metal mineralization within
the Baimka trend in the western Chukchi Peninsula have been preformed. Porphyry copper–molybdenum–
gold deposits and prospects of the Baimka trend are spatially related to monzonitic rocks of the Early Cretaceous
Egdygkych Complex. Four types of precious metal-bearing assemblages have been identified: (1) chalcopyrite
+ bornite + quartz with high-fineness native gold enclosed in bornite, (2) low-Mn dolomite + quartz +
sulfide (chalcopyrite, sphalerite, galena, tennantite-tetrahedrite ± tourmaline with low-fineness native gold
and hessite, and (3) rhodochrosite + high-Mn dolomite + quartz + sulfide (chalcopyrite, sphalerite, galena,
tennantite-tetrahedrite) with low-fineness native gold, electrum, acanthite, Ag and Au–Ag tellurides, and Ag
sulfosalts, and (4) calcite + quartz + sulfide (chalcopyrite, sphalerite, galena) with low-fineness native gold,
Ag sulfides and selenides, and Ag-bearing sulfosalts. Study of fluid inclusions from quartz, sphalerite, and
fluorite have revealed that hydrothermal ores within the Baimka Trend precipitated from fluids with strongly
variable salinity at temperatures and pressures ranging from 594 to 104oC and from 1200 to 170 bar, respectively.
An indicator of vertical AgPbZn/CuBiMo geochemical zoning is proposed. The value range of this
indicator makes it possible to estimate the erosion level of the porphyry–epithermal system. The erosion level
of the Baimka deposits and prospects deepens in the following order: Vesenny deposit → Pryamoi prospect →
Nakhodka prospect → Peschanka deposit → III Vesenny prospect.