Composition and metal contents of ore-forming fluids of the Kalguty Mo-W(Be) deposit (Gorny Altai)

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• 作者：A.A. Borovikov^a ; ^{borovik@igm.nsc.ru" class="auth_mail" title="E-mail the corresponding author} ; V.A. Goverdovskiy^b ; A.S. Borisenko^a ; ^c ; N.V. Bryanskiy^d ; S.I. Shabalin^a ; ^c
• 关键词：Mo&ndash ; W deposits ; fluids inclusions ; redox potential ; metal-bearing ore-forming fluids
• 刊名：Russian Geology and Geophysics
• 出版年：2016
• 出版时间：April 2016
• 年：2016
• 卷：57
• 期：4
• 页码：507-518
• 全文大小：1087 K

文摘

Based on results of study of fluid inclusions, we have established the specific fluid regime of formation of the Kalguty Mo–W(Be) deposit (Gorny Altai). Using classical thermobarogeochemistry (cryo- and thermometry) and modern microprobing methods (Raman spectroscopy and LA-ICP-MS), we studied fluid inclusions in quartz of quartz–wolframite veins (ore formation stage I), specific “quartz core” (quartz lens), and pyrite-chalcopyrite-molybdenite paragenesis (ore formation stage II). The results of study show that the quartz–wolframite veins of the Kalguty deposit formed with the participation of reduced W-Sb-bearing fluids with a salt content of up to 5.9 wt.%. Their gas phase consisted of CO₂, N₂, and CH₄. Formation of pyrite-chalcopyrite-molybdenite mineralization involved oxidized hot (530–420 °C) fluids with the average salt content of 9.3 wt.%. Their gas phase was of high density (up to 0.55) and consisted of CO₂, N₂, and H₂S. The pressure of the mineral-forming environment varied from 50 to 25 MPa. The fluids contained Cu, Mo, Bi, and S. The productive greisen-vein Mo–W(Be) mineralization of the Kalguty deposit resulted from the superposition of greisen molybdenite-chalcopyrite mineralization on parageneses of earlier formed quartz-wolframite veins. Oxidized metal-bearing fluids that formed the Mo mineralization of the Kalguty deposit have high contents of S and are geochemical analogs of magmatic metal-bearing ore-forming fluids of the Central Aldan porphyry Cu-Au-Mo deposits, which are genetically related to alkaline massifs. This suggests the significant influence of the mantle source on the formation of the Kalguty rare-metal ore-magmatic system. The same is evidenced from the sulfur isotope composition of chalcopyrite, molybdenite, and pyrite from ore parageneses, falling in the narrow range of δ³⁴S‰ from − 1.2 to + 2.9 corresponding to the isotope composition of mantle sulfur.