http://www.cnr.it/ontology/cnr/individuo/prodotto/ID39711
Water speciation and Sr isotopic exchanges during water-melt interaction: a combined NMR-TIMS study on the Cretaio Tephra (Ischia Island, South Italy) (Articolo in rivista)
- Type
- Label
- Water speciation and Sr isotopic exchanges during water-melt interaction: a combined NMR-TIMS study on the Cretaio Tephra (Ischia Island, South Italy) (Articolo in rivista) (literal)
- Anno
- 2004-01-01T00:00:00+01:00 (literal)
- Alternative label
Slejko F.F., Petrini R., Orsi G., Piochi M., Forte C. (2004)
Water speciation and Sr isotopic exchanges during water-melt interaction: a combined NMR-TIMS study on the Cretaio Tephra (Ischia Island, South Italy)
in Journal of volcanology and geothermal research
(literal)
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
- Slejko F.F., Petrini R., Orsi G., Piochi M., Forte C. (literal)
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- Rivista
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- ISI Web of Science (WOS) (literal)
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
- Dipartimento di Scienze della Terra,via Weiss 8,I-34127,Trieste,Italy
Osservatorio Vesuviano ^INGV,via Diocleziano 328,I-80124,Napoli,Italy
Istituto per i Processi Chimico-Fisici,CNR, Pisa (literal)
- Titolo
- Water speciation and Sr isotopic exchanges during water-melt interaction: a combined NMR-TIMS study on the Cretaio Tephra (Ischia Island, South Italy) (literal)
- Abstract
- In order to improve the microscopic understanding of the water -magma interaction process during explosive
volcanism,volcanic glasses representative of deposits with sedimentological characteristics suggesting different water/
melt ratios were studied by a combination of the nuclear magnetic resonance (NMR)and TIMS methods.The glasses
were separated from pumices of two surge layers and one fallout bed of the Cretaio Tephra (Ischia Island,Italy),
which is the product of an explosive eruption that occurred at Ischia in the second century BC.The 29 Si CP -MAS
NMR experiments indicate the occurrence of 1 H -29 Si dipolar couplings in glasses from the phreatomagmatic activity,
suggesting the presence of hydrogen atoms in proximity of silicon atoms.This feature is not detected in the glass from
the deposit of the magmatic explosion.1 H MAS NMR spectra reveal different peaks attributed to different hydrous
species characterized by different motional properties.These include rigid H2O groups isolated in the glass structure,
more mobile water species and possibly structural hydroxyl groups.1 H MAS NMR spectra recorded after deuteration
experiments of the glass at a temperature up to 300 C revealed that the exchange reactions of the D2O vapor with
hydrogen were limited to the most mobile water species,possibly on vesicle surfaces or in channels.The hydrogen
concentration linearly correlates with the 87 Sr/86 Sr isotope ratio in glasses,suggesting isotopic tracer exchanges
between the Sr dissolved in the water vapor and the Sr in the silicon -oxygen network during hydration.It is proposed
that the uprising melt interacted with a hydrothermal system of seawater-derived fluids,characterized by relatively
high Sr isotopic composition. (literal)
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