Ilya V. Chaplygin

Re-determination of the crystal structure of heyrovskyite mineral Pb6Bi2S9 (Kudryavyi Volcano, Iturup Island, Kurils, Russia)

Heyrovskyite mineral Pb6Bi2S9 from fumarole exhalations of the Kudryavyi volcano (Iturup island, Kurils, Russia) is studied by X-ray crystallography (Bruker Nonius X8 Apex with a 4K CCD detector, R = 0.0405). Unit cell parameters are: a = 4.1457(1) Å, b = 13.7421(5) Å, c = 31.5005(12) Å, V = 1794.6(1) Å3, Z = 4, dx = 7.216 g/cm3, Cmcm space group, R=0.0405. The resulted structure is similar to the known structures of heyrovskyites from other deposits with some variation in the cation composition.

Chemical composition and metal capacity of magmatic gases of Gorelyi volcano, Kamchatka

The high-temperature (865°C according to data of an IR-camera) gases and the crater lake water of Gorelyi volcano were sampled in September 2011. The gas and condensate were collected from the active crater in bocca, which was formed in June 2010. The chemical composition and the δ18O and δD values of the condensate and lake water were analyzed. In comparison with the isotopic data on volcanic condensates of the adjacent Mutnovskii volcano, the data points of samples from Gorelyi volcano fall to the mixing line of meteoric and magmatic water. The isotopic characteristics of the water component of the fluid mostly correspond to the high-temperature equilibrium with silicate rocks or melts; the portion of local meteoric water is ~25%. The high metal content of gases of the volcano is determined. The total removal of Cu, Zn, Pb, Mo, Cd, In, Sn, Tl, and Bi by gases of Gorelyi volcano (~30 t/year) comparable to that of the Kudryavyi volcano (20–80 t/year) indicates the high ore-bearing capacity of the volcanic gas fluids.

Sources of rhenium and osmium enrichment in fumaroles, sulphide sublimates and volcanic rocks from the Kudriavy volcano

Rhenium loss through magma degassing could be partly balanced by rhenium enrichment in fumarolic magmatic gases and Re-bearing precipitates, as may be the case for the Kudriavy volcano associated with an active subduction zone. The relatively unradiogenic 187Os/188Os isotope ratios (0.122 up to 0.152) and high Os contents (averaging 0.6 ppb) of fumarolic gas condensates imply that significant Re and Os are remobilised from depleted MORB mantle. Involvement of a Re-rich component is evident from high Re concentrations in high-temperature gas condensates, ranging from 7 to 200 ppb. Indeed, Re-rich Os-poor components such as organic-rich subducted sediments and volcanic rocks do not significantly shift the isotopic composition of fumarolic products. The relatively radiogenic composition of the dacite-andesite-basaltic arc volcanics (187Os/188Os ratio up to 0.58), however, could result from significant Os (and Re) input from subducted sediments.