Petrogenesis and evolution of Mt. Vulture alkaline volcanism (Southern Italy)

L. Beccaluva*, M. Coltorti, P. Di Girolamo, L. Melluso, L. Milani, V. Morra, F. Siena

*Corresponding author for this work

Research output: Contribution to journalArticle

82 Citations (Scopus)

Abstract

The Late Pleistocene Mt. Vulture strato-volcano developed at the intersection of NE-SW and NW-SE lithospheric fault systems, on the easternmost border of the Apennine compressional front overthrust onto the Apulian foreland. The initial phase of the volcanic activity is represented by pyroclastic deposits, including lava blocks, and subordinate eccentric domes, mostly phonolitic in composition. The later stages of activity formed the bulk of the strato-volcano (pyroclastic products and subordinate lavas), mostly tephritic in composition, with minor intercalations of basanite, melafoidite and melilitite lavas and dikes. Variations in rock and mineral composition suggest that the volumetrically pre-dominant basanite-tephrite (foidite)-phonotephrite-phonolite series can be accounted for by fractional crystallization processes starting from basanitic parental magmas, in agreement with the remarkably constant 87Sr/86Sr isotopes (0.70586-0.70581). Mass-balance calculations indicate that the variably differentiated magmas may have been produced by removal of wehrlite, clinopyroxenite and syenite cumulates, some of which are occasionally found as cognate xenoliths in the volcanics. Fractionation processes probably developed in multiple-zoned magma chambers, at depths of 3-5 km, corresponding to the tectonic discontinuity between the allochthonous Apennine formations and the underlying Apulian platform. Highly differentiated phonolitic magmas capping the magma chambers and their conduits thus appear to have fed the initial volcanic activity, whereas dominantly tephritic products were erupted in later stages. The least evolved mafic magmas, namely basanites, mela-foidites and melilitites, are characterized by diverse Na/K ratios and critical SiO2-undersaturation, which indicate their derivation as independent melts generated from distinct, heterogeneously enriched mantle sources and by variable partial melting degrees.

Original languageEnglish
Pages (from-to)277-297
Number of pages21
JournalMineralogy and Petrology
Volume74
Issue number2-4
DOIs
Publication statusPublished - 2002
Externally publishedYes

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