Crustal contamination and crystal entrapment during polybaric magma evolution at Mt. Somma–Vesuvius volcano, Italy: Geochemical and Sr isotope evidence

Piochi, Monica; Ayuso, Robert A.; Vivo, Benedetto De; Somma, Renato

doi:10.1016/j.lithos.2005.05.009

Cited by 62 publications

(61 citation statements)

References 65 publications

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“…7a, b), as also two other pumices from the mortars of Forum of Trajan analyzed in (GA-p2, BU-p1) do. A third mortar pumice from the Grande Aula of Trajan Markets (GA-p1), that attributed to the Vesuvius based also on its mineralogic composition, shows Zr/TiO 2 vs Nb/TiO 2 composition quite similar to that of the early explosive activity of Somma-Vesuvius ("Pomici di Base" and "Pomici Verdoline", Ayuso et al, 1998;Landi et al, 1999: Paone, 2006: Piochi et al, 2006Fig. 7a).…”

Section: Ports Of Claudius and Anxurmentioning

confidence: 89%

Provenance materials for Vitruvius' harenae fossiciae and pulvis puteolanis : Geochemical signature and historical–archaeological implications

D'Ambrosio¹,

Marra

Cavallo

et al. 2015

Journal of Archaeological Science: Reports

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Section: Ports Of Claudius and Anxurmentioning

confidence: 89%

Provenance materials for Vitruvius' harenae fossiciae and pulvis puteolanis : Geochemical signature and historical–archaeological implications

D'Ambrosio¹,

Marra

Cavallo

et al. 2015

Journal of Archaeological Science: Reports

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“…The geochemical signature of magma-carbonate interaction can sometimes be seen within volcanic products, and is known as "carbonate assimilation" (e.g., Wenzel et al, 2002;Barnes et al, 2005;Gaeta et al, 2006;Piochi et al, 2006;Chadwick et al, 2007;Freda et al, 2008;Deegan et al, 2010;Mollo et al, 2010a). Recent petrological studies have documented in detail that magma contamination is marked by the overgrowth of Ca-rich phases (mainly calcic clinopyroxene) on primary minerals (essentially olivine); as a result, the magma becomes progressively depleted in silica and enriched in alkalis.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Thermal weakening of the carbonate basement under Mt. Etna volcano (Italy): Implications for volcano instability

Heap

Mollo

Vinciguerra

et al. 2013

Journal of Volcanology and Geothermal Research

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The physical integrity of a sub-volcanic basement is crucial in controlling the stability of a volcanic edifice. For many volcanoes, this basement can comprise thick sequences of carbonates that are prone to significant thermally-induced alteration. These debilitating thermal reactions, facilitated by heat from proximal magma storage volumes, promote the weakening of the rock mass and likely therefore encourage edifice instability. Such instability can result in slow, gravitational spreading and episodic to continuous slippage of unstable flanks, and may also facilitate catastrophic flank collapse. Understanding the propensity of a particular sub-volcanic basement to such instability requires a detailed understanding of the influence of high temperatures on the chemical, physical, and mechanical properties of the rocks involved. The juxtaposition of a thick carbonate substratum and magmatic heat sources makes Mt. Etna volcano an ideal candidate for our study. We investigated experimentally the effect of temperature on two carbonate rocks that have been chosen to represent the deep, heterogeneous sedimentary substratum under Mt. Etna volcano. This study has demonstrated that thermalstressing resulted in a progressive and significant change in the physical properties of the two rocks. Porosity, wet (i.e., water-saturated) dynamic Poisson's ratio and wet Vp/Vs ratio all increased, whilst P-and S-wave velocities, bulk sample density, dynamic and static Young's modulus, dry Vp/Vs ratio, and dry dynamic Poisson's ratio all decreased. At temperatures of 800 °C, the carbonate in these rocks completely dissociated, resulting in a total mass loss of about 45% and the release of about 44 wt.% of CO 2 . Uniaxial deformation experiments showed that high in-situ temperatures (> 500°C) significantly reduced the strength of the carbonates and altered their deformation behaviour. Above 500 °C the rocks deformed in a ductile manner and A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPTthe output of acoustic emissions was greatly reduced. We speculate that thermally-induced weakening and the ductile behaviour of the carbonate substratum could be a key factor in explaining the large-scale deformation observed at Mt. Etna volcano. Our findings are consistent with several field observations at Mt. Etna volcano and can quantitatively support the interpretation of (1) the irregularly low seismic velocity zones present within the sub-volcanic sedimentary basement, (2) the anomalously high CO 2 degassing observed, (3) the anomalously high Vp/Vs ratios and the rapid migration of fluids, and (4) the increasing instability of volcanic edifices in the lifespan of a magmatic system. We speculate that carbonate sub-volcanic basement may emerge as one of the decisive fundamentals in controlling volcanic stability.

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“…3). Orsi et al 2004) Somma-Vesuvius rocks show 87 Sr/ 86 Sr values ranging from 0.70620 to 0.70810 and 143 Nd/ 144 Nd ratios ranging from 0.51261 to 0.51238 (Civetta et al 1987(Civetta et al , 1991(Civetta et al , 2004Civetta and Santacroce 1992;Caprarelli et al 1993;Santacroce et al 1993;Cioni et al 1995;Ayuso et al 1998;Somma et al 2001;Piochi et al 2006;Di Renzo et al 2007). Isotopic data have been largely used to constrain the genesis of the Vesuvius magmas, located in a mantle source variably enriched in sediment derived fluids and melts (e.g., Ayuso et al 1998;Di Renzo et al 2007, and references therein).…”

Section: Geological Outlinesmentioning

confidence: 99%

The “Pomici di mercato” Plinian eruption of Somma-Vesuvius: magma chamber processes and eruption dynamics

et al. 2007

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The Pomici di Mercato (PdM, 8,010±40 a), also known in the literature as Pomici Gemelle or Pomici di Ottaviano, is one of the oldest Plinian eruptions of SommaVesuvius. This eruption occurred after the longest (7 ka) quiescence period of the volcano and was followed by more than 4 ka of repose. The erupted magma is phonolitic in composition. All the products have very low phenocrysts content (less than 3%) and show evidence of mineralogical disequilibria. They contain K-feldspar ± clinopyroxene (salite and diopside) ± plagioclase ± garnet ± biotite ± amphibole ± apatite ± Fe-Ti oxides. Pumice fragments collected at different stratigraphic heights are slightly less evolved and more enriched in radiogenic Sr composition upsection. The glass composition is fairly homogeneous in single pumice fragment and among pumice fragments from different layers. Glass separated from pumice fragments collected at different stratigraphic heights is homogeneous in the Sr-isotope composition (around a value of 0.70717). Glass is in isotopic equilibrium with salite throughout the entire sequence and with diopside at the base of the sequence. Diopside becomes more radiogenic upsection, reaching a value of 0.707458±7, whereas feldspar is consistently slightly less radiogenic than glass. Nd-isotope composition is fairly uniform (ca. 0.51247) through the whole sequence. The isotopic disequilibria among glass, feldspar and diopside, together with the homogeneous isotopic composition of pumice glass in equilibrium with salite, and the mineralogical disequilibria between plagioclase and K-feldspar, imply that most of the diopside and plagioclase crystals are xenocrysts incorporated into the phonolitic magma during residence in a magma chamber and/or during ascent towards the surface. The PdM Tephra are compositionally and isotopically similar to the phonolitic, first-erupted products of the subsequent Pomici di Avellino Plinian eruption. On the basis of this similarity, we suggest that the magma feeding both eruptions resulted from the tapping of a unique magma chamber. Prior to the PdM eruption, this chamber was formed by a large and homogeneous phonolitic magma body. After the PdM eruption, as a consequence of new arrivals of more radiogenic in Sr, less-differentiated magma batches, the magma chamber progressively developed a slightly stratified phonolitic uppermost portion, capping a tephriphonolitic layer, both emitted during the subsequent Pomici di Avellino eruption.

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Crustal contamination and crystal entrapment during polybaric magma evolution at Mt. Somma–Vesuvius volcano, Italy: Geochemical and Sr isotope evidence

Cited by 62 publications

References 65 publications

Provenance materials for Vitruvius' harenae fossiciae and pulvis puteolanis : Geochemical signature and historical–archaeological implications

Provenance materials for Vitruvius' harenae fossiciae and pulvis puteolanis : Geochemical signature and historical–archaeological implications

Thermal weakening of the carbonate basement under Mt. Etna volcano (Italy): Implications for volcano instability

The “Pomici di mercato” Plinian eruption of Somma-Vesuvius: magma chamber processes and eruption dynamics

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