Barite from the Saf’yanovka VMS deposit (Central Urals) and Semenov-1 and Semenov-3 hydrothermal sulfide fields (Mid-Atlantic Ridge): a comparative analysis of formation conditions

Abstract

Hydrothermal and diagenetic barites from colloform and clastic pyrite-rich ores from the weakly metamorphic Saf'yanovka volcanogenic massive sulfide deposit (Devonian, Central Urals) were studied in comparison with barite from similar modern seafloor deposits from the mid-Atlantic Ridge (Semenov-1 and Semenov-3 hydrothermal fields). Hydrothermal barites from all the studied deposits exhibit similar morphology: they occur as tabular crystals or their aggregates. In contrast, diagenetic barite from clastic ores of the Saf'yanovka deposit occur as compact aggregates of deformed, broken, or slightly curved tabular crystals with stylolite boundaries. The variable Sr contents in the studied barites show no relationship with the genetic types. The average δ 34 S values of hydrothermal barite from both ancient and modern colloform sulfides (+22.9 ‰, Saf'yanovka deposit; +21.2‰, Semenov-1 field) match those of Silurian-Devonian and contemporary seawater, respectively. The lower δ 34 S of hydrothermal barite from clastic sulfides of the Semenov-3 field (+19.6 ‰), which is associated with high-Se, high-temperature chalcopyrite, indicates light sulfur contribution from oxidation of fluid H 2 S. The higher average δ 34 S of diagenetic barite from clastic

Sulfide Breccias from the Semenov-3 Hydrothermal Field, Mid-Atlantic Ridge: Authigenic Mineral Formation and Trace Element Pattern

“…Sulfide breccias from the Semenov-3 hydrothermal field were briefly described by Safina et al [46]. Here, we significantly expand this description providing textural-structural relationships between sulfide clasts and authigenic mineral assemblages.…”

“…The well-formed barite laths in the breccia matrix likely formed during early diagenesis were further replaced by late diagenetic coarse-crystalline pyrite (Figures 4d and 14). Finally, the previously studied druses of large euhedral barite crystals with formation temperatures of 265-335 • C indicate a late high-temperature hydrothermal overprint [46].…”

Chimneys in Paleozoic massive sulfide mounds of the Urals VMS deposits: Mineral and trace element comparison with modern black, grey, white and clear smokers

“…Methane and N 2 detected by gas chromatography are common in fluid inclusions of barite from the Safyanovskoye deposit (Safina et al, 2016). Galena-tetrahedrite assemblage with native gold typical of the sphalerite-barite-chalcopyrite chimneys of the Safyanovskoye deposit is similar, probably, with grey clear smokers of the Hakurei modern vent site.…”

Extreme enrichment of selenium in the Apliki Cyprus-type VMS deposit, Troodos, Cyprus

“…The Apliki mineralogy is dominated by chalcopyrite indicating mineralization temperatures of 280–350°C (e.g. Gill et al , 2016; Safina et al , 2016) (Fig. 14, stage I).…”