Sources of unique rhenium enrichment in the Kudriavy volcano, Kurile Islands

The rhenium loss through magma degassing (Sun et al.,
2003) could be partly balanced by rhenium enrichment in
fumarolic magmatic gases and Re-bearing precipitates, as it is
a case for the Kudryavy subduction zone volcano, Kurile
Islands. The sources of this unusual Re enrichment could be
elucidated using the Re-Os isotopic systematic. 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 a significant part of Re and Os was
remobilised from depleted MORB mantle. Involvement of Rerich
component is evident from high Re concentrations in
high-temperature gas condensates, ranging from 7 to 200 ppb.
Indeed, the radiogenic Re-rich Os-poor components such as
organic-rich subducted sediments (≥20%) and volcanic rocks
(≥20%) do not shift significantly the isotopic composition of
fumarolic products. The relatively radiogenic composition of
the andesite-basaltic arc volcanics (187Os/188Os ratio up to
0.58) could result in the significant Os (and Re) input from
subducted sediments.

References
Sun W., Benett V.C., Eggins S..M., Kamenetsky V.S. and
Arculus R.J. (2003). Nature, 422, 294-297.