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Ivan Baksheev, Lomonosov Moscow State University (Russian Federation)
Vsevolod Prokof'ev, Institute of Geology, Geochemistry, Mineralogy and Petrography, RAS (Russian Federation)
Vladimir Ustinov, Vernadsky Institute of geochemistry and Analytical Chemistry, RAS (Russian Federation)
Georgii Zaraiskii, Institute of Experimental Mineralogy, RAS (Russian Federation)
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We have studied tourmalines from schist-type emerald (Malyshevo, Russia), Sn greisen (Sherlovaya Gora, Russia and Cornwall, UK), Sn volcanic-related (Mramorny district, Russia), Cu-porphyry (Aktogai, Kazakhstan; Kafan, Armenia), ultramafic talc (Shabry and Syrostan, Russia), and different-depth gold (Berezovsky and Darasun, Russia) deposits. In the Emerald Mines, tourmalines can be classed as dravite to "fluor-dravite" with different values of XFe 0.12-0.37 and F 0-0.75 apfu. The Fe3+/Fetot ratio is low and ranges from 0.04 to 0.08. Calculated δ18OH2O and δDH2O values of fluid responsible for the tourmaline formation range from +7.7 to +8.3‰ and from -65 to -59‰, respectively, indicating magmatic source. In general, tourmalines from Sn greisen deposits can be classed as schorl to "fluor-schorl" with XFe 0.43-1.0 and F 0-0.58 apfu. The Fe3+/Fetot ratio is low and is ∼0.05. The δ18O (SMOW) value of studied tourmaline from Cornwall is +12.0‰. Among cations in emerald and greisen tourmalines, the major type of substitution is MgFe-1. Tourmalines from Sn volcanic-related deposits can be classed as schorl to "oxy-" and "flour-schorl" of two generations with XFe 0.86-0.95 and F 0-0.57 apfu for tourmaline-I associated with cassiterite and XFe 0.51-0.75 and F 0-0.25 apfu for tourmaline-II associated with sulfides. The Fe3+/Fetot ratio is higher than in the greisen and emerald deposits ranging from 0.11 to 0.25. Among cations, the major type of substitution is AlFe-1. The δ18O (SMOW) value varies from -7.2 to +9.5‰ indicating significant influx of meteoric water in mineralizing fluid. Tourmalines from the studied Cu-porphyry deposits can be classed as schorl-dravite with XFe 0.47-0.75 and F 0-0.35 apfu. The Fe3+/Fetot ratio is 0.59. Among cations, the major type of substitution is AlFe-1. The δ18O (SMOW) value of tourmaline from Kafan is +6.5δ. Tourmalines from talc deposits may be classed as dravite with XFe 0.23-0.46 and F 0-0.20 apfu. The Fe3+/Fetot ratio ranges from 0.39 to 0.55. Among cations, the major type of substitution is MgFe-1. Calculated δ18OH2O and δDH2O range from +7.6 to +11.1‰ and from -62 to -31‰, respectively, indicating magmatic fluid source with probable influx of metamorphic water. Early tourmalines from deep-seated gold deposits (P 1.7-2.5 kb) are schorl-dravite with XFe 0.08-0.46 and F 0-0.20 apfu. The Fe3+/Fetot ranges from 0.12 to 0.60. Calculated δ18OH2O and δDH2O range from +2.9 to +5.7‰ and from -61 to -57‰, respectively, indicating magmatic fluid source probably with influx of metamorphic water. Early tourmalines from the shallow gold deposits (P 0.5-1.5 kb) are schorl ("oxy-schorl")-dravite ("oxy-dravite"), with XFe 0.09-0.74 and F 0-0.37 apfu. The Fe3+/Fetot ranges from 0.50 to 0.85. Among cations, the major type of substitution is AlFe-1. Calculated δ18OH2O value varies from +0.1 to +7.7‰ indicating significant influx of meteoric water.
This work has been supported by IGCP-540.
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