1,721,033 research outputs found
Possible deep origin of sulphur output at Vulcano (Southern Italy) in the light of melt inclusion studies
No full textA study of melt inclusions at Vulcano (Aeolian islands,Italy): insights on the primitive magmas and on the volcanic feeding system.feeding system
No full textThe relationship between potassic, calc-alkaline and Na-alkaline magmatism in South Italy volcanoes: A melt inclusion approach
No full textmelt-mineral-fluid interactions in ultramafic nodules from alkaline lavas of Mount Etna (Sicily, Italy): Melt and fluid inclusion evidence
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Petrogenesis of mafic lavas from the northernmost sector of the Iblean district (Sicily)
No full textA wide spectrum of mafic volcanic rocks, ranging from Qz-tholeiites to strongly undersaturated alkaline lavas (ankaratrites), were erupted during Upper Miocene and Plio-Pleistocene in the Iblean area. The rather primitive nature of these products indicates that the differentiation processes occurred from the source region to the surface affected these magmas only in subordinate way.For this reason, on the basis of the presented chemical and mineralogical data, the petrogenetic study of the Iblean volcanic suite is mainly aimed at constraining and evaluating the partial melting processes and the nature of the mantle sources. The modelling of the available chemical data (both major and trace elements) indicates that these near-primary melts cannot have been produced by different degrees of melting from the same source; this would suggest that their differences reflect, at least in part, significant variations in source composition.The calculations suggest that suitable mantle sources are represented by variously "enriched" spinel-lherzolites, containing accessory phases such as amphibole for tholeiitic and transitional basalts (A-Th, B-Th and TB), amphibole + phlogopite for alkaline lavas (AB, Bn) and amphibole + phlogopite +/- apatite +/- carbonate for highly alkaline rocks (A-Ank, B-Ank).In this light, the wide range of mafic lavas collected in the Iblean area appear to have been produced by different degrees of partial melting, ranging from 2-3% for the highly alkaline rocks to 22 % for the Qz-tholeiites, of a lithospheric mantle characterized by small-scale heterogeneity.This process has been favoured by relatively high thermal conditions in the mantle beneath the studied area and induced by the Miocene and Plio-Pleistocene transcurrent-extensional tectonic regime.The chemical compositions of the various lavas depend on the relative proportions of the differently enriched mantle domains involved. Small degrees of partial melting sampled preferentially low-solidus enriched domains, producing the alkaline magmas. At higher partial melting degrees, larger domains of less enriched mantle portions contributed to the magmatogenetic processes, thus generating the subalkaline magmas
Inclusioni fluide e vetrose in noduli ultramafici e fenocristalli di lave alcaline etnee
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Environmental impact of the acid fumarole plume of a passively degassing volcano (Vulcano Island, Italy)
No full textAbstract This paper investigates the
role played by the fumarolic plume
of a passive degassing volcano in the
genesis of rock coatings (RC) and in
the introduction and re-distribution
of metals and trace elements in the
surficial environment. At La Fossa
active volcano (Vulcano Island) and
in the surrounding environment RC
develop owing to exposure of the
ground surface to the volcanic acid
plume produced by the passive degassing
of La Fossa. Significant positive
anomalies of a wide variety of
metals and trace elements (including
Bi, Ag, Se, Te, Sb, Pb, As, Cu, Tl
and Cd) were observed either in
distal and proximal RC. Most of
these anomalies are interpreted to be
the result of the transport and subsequent
deposition of trace elements,
likely to form volatile compounds, in
the fumarolic plume. Two main
processes seem to control the geochemistry
of RC: one is represented
by the leaching and subsequent
deposition of elements from the
proximal toward the distal RC; the
other is the direct input of trace
elements carried by the emitted volcanic
aerosol. The fact that most of
the trace elements (particularly Pb,
As, Tl, Bi, Te, Se, Cd) enriched in
the RC of Vulcano are highly toxic
and potentially dangerous to health
in high concentration, indicates that
the atmospheric metal injection by
the quiescently degassing La Fossa
volcano together with the subsequent
deposition and remobilization
by means of surficial waters
may represent an environmental
hazard that should be taken into
account in evaluating the potential
impact of volcanic air pollution on
human health
Assessment of a shallow magmatic system: the case of the 1888-90 eruption, Vulcano island, Italy
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