1,721,129 research outputs found
Fluorophlogopite and F-rich phases in limestone clasts from the Campanian Ignimbrite quarried at Fiano (southern Italy): mineralogical, geochemical and volcanological insights.
No full textFluorine-rich metamorphosed xenoliths associated to the distal Campanian Ignimbrite (CI) tephra (Campania region,
southern Italy) have long attracted the interest of the mineralogical community (i.e. Scacchi, 1890; Zambonini, 1919;
Masi & Turi, 1972; Balassone et al., 2002). These rocks derive from the Mesozoic carbonate lithotypes of the
Campanian Apennine, embedded in the pyroclastic flow and presently resting at the bottom of the tuff formations. The
sedimentary protoliths suffered from the action of hot, volatile-rich pyroclastic flow, and consequently were affected by
thermal metamorphism to various degrees. Their peculiarity is the occurrence of F- and Mg-bearing phases, with an
ubiquitous presence of neoformed fluorite. The occurrence at Fiano quarries (the so-called “Tufare”) is the classical
locality for these rock xenoliths. Similar rocks were also found in the CI of the Caserta area, and in the Latium region
(Colli Albani). This research aims both at a crystal chemical study of fluorophlogopite occurring in the Fiano xenoliths,
and at a geochemical and volcanological survey, to constrain the petrogenesis processes related to this rare F-, Mg-rich
assemblage and to CI.
The analysed samples belong to two lithotypes: mica-bearing clasts and variably metamorphosed carbonate blocks.
The former lithotype is represented by abundant fluorite, followed by fluorophogopite, F-rich chondrodite, fluoborite,
diopside and (Fe,Mg)-oxides. Minor to trace contents of calcite, humite, tremolite, and grossular also occur. Carbonate
rocks can show calcite only, or also trace amounts of fluorite. The Fiano micas composition approaches that of the
Vesuvius micas from the 1872 eruption (Balassone et al., 2013). The micas belong to the 1M polytype and have crystal
chemical features typical of fluorophlogopites i.e., low c lattice parameter (~ 10.13 Å), (~ 2.060 Å) and (~ 3.135 Å)
distances. New data on minor to ultratrace elements amounts found in the studied clasts, together with Carbon and
Oxygen isotope data will be reported and interpreted in a petrogenetic and volcanological frame.
Balassone G., Franco E., Mattia C.A., Petti C. & Puliti R. 2002. Re-examination of fluosiderite, an unknown mineral
from southern Italy: equal to fluorine-rich chondrodite. Eur. J. Min., 14, 151-155.
Balassone G., Scordari F., Lacalamita M., Schingaro E., Mormone A., Piochi M., Petti C. & Mondillo N. 2013.
Trioctahedral micas in xenolithic ejecta from recent volcanism of the Somma-Vesuvius (Italy): crystal chemistry and
genetic inferences. Lithos, 160-161, 84-97.
Masi U. & Turi B. 1972. Frazionamento isotopico del carbonio e dell'ossigeno negli inclusi calcarei metamorfosati del
"Tufo grigio campano" Auct. di Fiano (Salerno). Per. Min., 41, 291-310.
Scacchi A. 1890. La regione vulcanica fluorifera della Campania. Mem. R. Com. Geol. It., I, 1-48.
Zambonini F. 1919. Il tufo pipernoide della Campania e i suoi minerali. Mem. Descr. Carta Geol. It., 7, 130 pp
Speciazione acquosa in fusi silicatici: evidenze spettroscopiche della interazione acqua-magma in vetri vulcanici della eruzione del Tufo Giallo Napoletano nella Caldera dei Campi Flegrei.
No full textMelt structures at the glass transition by NMR spectroscopy. parameters in volcanin processes modelling
No full textDiverse magma sources and crustal contamination processes at Mount Somma- Vesuvius (Italy): geochemical and Sr-isotopical evidence.
No full textCrustal contamination and crystal entrapment during polybaric magma evolution at Mt. Somma-Vesuvius volcano, Italy: geochemical and Sr isotope evidence.
No full textModeling of the thermal state of Mt. Vesuvius from 1631 AD to present and the role of CO2 degassing on the volcanic conduit closure after the 1944 AD eruption
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