Trace element and Pb–B–Li isotope systematics of olivine-hosted melt inclusions: insights into source metasomatism beneath Stromboli (southern Italy)

Autor: Eizo Nakamura, Federica Schiavi, Massimo Tiepolo, Katsura Kobayashi, Riccardo Vannucci
Přispěvatelé: Dipartimento di Scienze della Terra e dell'Ambiente [Pavia], Università degli Studi di Pavia, Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Study of the Earth's Interior, Istituto di Geoscienze e Georisorse (IGG), Consiglio Nazionale delle Ricerche [Roma] (CNR), Instituto di Geoscienze e Georisorse, Consiglio Nazionale delle Ricerche (CNR)
Rok vydání: 2011
Předmět:
Zdroj: Contributions to Mineralogy and Petrology
Contributions to Mineralogy and Petrology, Springer Verlag, 2012, 163 (6), pp.1011-1031. ⟨10.1007/s00410-011-0713-5⟩
Contributions to mineralogy and petrology 163 (2012): 1011–1031. doi:10.1007/s00410-011-0713-5
info:cnr-pdr/source/autori:Schiavi F. [1]; Kobayashi K. [2]; Nakamura E. [2]; Tiepolo M. [3]; Vannucci R. [1,3]/titolo:Trace element and Pb-B-Li isotope systematics of olivine-hosted melt inclusions: insights into source metasomatism beneath Stromboli (southern Italy)/doi:10.1007%2Fs00410-011-0713-5/rivista:Contributions to mineralogy and petrology/anno:2012/pagina_da:1011/pagina_a:1031/intervallo_pagine:1011–1031/volume:163
ISSN: 1432-0967
0010-7999
Popis: We studied the elemental and isotopic (Pb, B and Li isotopes) composition of melt inclusions hosted in highly forsteritic (Fo(83-91)) olivines that were collected from San Bartolo lava and pumice (ST79p, ST82p and ST531p) samples erupted by Stromboli in historical times. The studied melt inclusions have primitive calcalkaline to shoshonitic basaltic compositions. They cover a compositional range far wider than that exhibited by the whole-rocks and differ in key trace element ratios. San Bartolo melt inclusions are characterized by lower incompatible trace element abundances, higher ratios between fluid-mobile (B, Pb, U and LILE) and less fluid-mobile (REE, Th, HFSE) elements and lower La/Yb ratios relative to the pumice-hosted melt inclusions and pumiceous melts erupted during paroxysmal events. Trace elements, along with different Pb, B and Li isotopic signatures, attest to source heterogeneity on the small scale and provide new insights into subducted components beneath Stromboli. Results of a mixing model suggest that metasomatism of the mantle source of pumice-hosted melt inclusions was driven by solute-rich high-pressure fluids (< 20%) expelled from the deep portion of the slab. Heterogeneous Pb isotopic composition together with light delta B-11 (-8.6 to -13.7aEuro degrees) and delta Li-7 (+2.3 to -1.7aEuro degrees) indicates that high-pressure liquids were released in variable proportions from highly dehydrated metabasalts and metasediments. On the other hand, the elemental and isotopic (delta B-11 similar to -1.9 to -5.9aEuro degrees) composition of San Bartolo melt inclusions is better explained by the addition of a prevalent aqueous component (similar to 2 to 4%) escaped at shallower depths from sediments and altered basaltic crust in almost equivalent proportions, with a smaller contribution by high-pressure fluids. Owing to the high-angle dip of the subducted cold Ionian slab, aqueous fluids and high-pressure fluids would rise through the mantle wedge and locally superimpose on each other, thus giving origin to variously metasomatized mantle domains.
Databáze: OpenAIRE
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