Home – Home – Jornals – Russian Geology and Geophysics 2005 number 3

Volcanogenic pyrite-polymetallic deposits are widespread in southern Siberia (Rudny Altai, eastern Tuva, northern Baikal region, and western Transbaikalia). They are divided into two groups according to their formation mechanism: volcanogenic hydrothermal (VHMS-type) (Kyzyl-Tashtyg deposit in Tuva; Korbalikhinskoe, Zolotushinskoe, Yubileinoe, and other deposits in Rudny Altai) and volcanosedimentary (SEDEX-type) (Kholodninskoe deposit in the northern Baikal region and Ozernoe deposit in western Transbaikalia).
Comparison of major ores and ore minerals during the volcanosedimentary and volcanogenic hydrothermal formation of pyrite-polymetallic deposits showed their significant difference in the spectrum and contents of trace elements.
Ores of the VHMS deposits have high concentrations of trace elements as they formed under drastic drop in temperature (as a result of boiling-up of solutions and their mixing with sea water), which caused mass deposition of ore matter and coprecipitation of accompanying elements, including their sorption by crystallizing sulfide minerals.
The poorer spectrum and lower concentrations of trace elements in ores of the SEDEX deposits are, on the contrary, related to the rhythmic formation of chemogenic ores from sea-floor brine pools. The reduced amount of endogenic sulfur and gradual reduction of sea water sulfur and its involvement in sulfide formation prevented rapid mass deposition of sulfides and, accordingly, coprecipitation of accompanying elements.