Carbonate globules have been found in amphibole-bearing glass veins of
peridotite xenoliths from Szentbekalla (Balaton Highland, Central
Hungary). Strong resorption of amphibole suggests multiple fluid-melt
infiltration. Textural features of carbonate globules and the
surrounding silicate glass indicate a magmatic melt origin for the
carbonate and exclude the possibility of significant alteration. The
application of the cpx structural barometer for clinopyroxenes formed in
the silicate glass indicates high-pressure vein formation.
Laser-ablation ICP-MS analyses revealed trace element zoning within the
carbonate. Uniform profiles observed for various elements within the
carbonate indicate that the zoning is related to non-diffusive mixing
during carbonate-silicate interaction rather than to element diffusion.
The trace element composition of the centers of the globules (e.g. low
Ce/Pb and Nd/Pb ratios) suggests a crustal origin for the carbonate
melt. The C, 0, and Sr isotope compositions of the calcite globules
(delta(13)C about - 14 parts per thousand; delta(18)O about 22 parts per
thousand; (87)Sr/(86)Sr = 0.70533) also argue for a crustal origin of
the carbonate melt. Trace element and C-O-Sr isotopic compositions of
calcite globules suggest that the carbonate melt was derived from
subducted material. Injection of the carbonate melt into the peridotite
triggered amphibole melting. The carbonate and silicate melts
intermingled, but their interaction was confined to the margins of
carbonate globules. Preservation of trace element zoning and element
diffusion calculations indicate that the vein-hosting peridotite was
rapidly brought to the surface after the carbonate melt injection. (C)
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