A limited role for metasomatized subarc mantle in the generation of boron isotope signatures of arc volcanic rocks
2019 | journal article. A publication with affiliation to the University of Göttingen.
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A limited role for metasomatized subarc mantle in the generation of boron isotope signatures of arc volcanic rocks
Tomanikova, L.; Savov, I. P.; Harvey, J.; de Hoog, J. C.; Churikova, T. G. ; Yogodzinski, G. M. & Gordeychik, B. N. (2019)
Geology, 47(6) pp. 517-521. DOI: https://doi.org/10.1130/G46092.1
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Details
- Authors
- Tomanikova, Lubomira; Savov, Ivan P.; Harvey, Jason; de Hoog, Jan C.M.; Churikova, Tatiana G. ; Yogodzinski, Gene M.; Gordeychik, Boris N.
- Abstract
- Metasomatized subarc mantle is often regarded as one of the mantle reservoirs enriched in fluid-mobile elements (FMEs; e.g., B, Li, Cs, As, Sb, Ba, Rb, Pb), which, when subject to wet melting, will contribute to the characteristic FME-rich signature of arc volcanic rocks. Evidence of wet melts in the subarc mantle wedge is recorded in metasomatic amphibole-, phlogopite-, and pyroxene-bearing veins in ultramafic xenoliths recovered from arc volcanoes. Our new B and δ11B study of such veins in mantle xenoliths from Avachinsky and Shiveluch volcanoes, Kamchatka arc, indicates that slab-derived FMEs, including B and its characteristically high δ11B, are delivered directly to a melt that experiences limited interaction with the surrounding mantle before eruption. The exceptionally low B contents (from 0.2 to 3.1 μg g–1) and low δ11B (from –16.6‰ to +0.9‰) of mantle xenolith vein minerals are, instead, products of fluids and melts released from the isotopically light subducted and dehydrated altered oceanic crust and, to a lesser extent, from isotopically heavy serpentinite. Therefore, melting of amphibole- and phlogopite-bearing veins in a metasomatized mantle wedge cannot alone produce the characteristic FME geochemistry of arc volcanic rocks, which require a comparatively large, isotopically heavy and B-rich serpentinite-derived fluid component in their source
- Issue Date
- 2019
- Journal
- Geology
- ISSN
- 0091-7613
- ISSN
- 0091-7613
- Language
- English