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dc.contributor.author
Kueter, Nico
dc.contributor.author
Cody, George D.
dc.contributor.author
Foustoukos, Dionysis I.
dc.contributor.author
Mysen, Bjorn O.
dc.date.accessioned
2022-09-28T12:16:27Z
dc.date.available
2022-09-28T06:48:43Z
dc.date.available
2022-09-28T12:16:27Z
dc.date.issued
2022-11-05
dc.identifier.issn
0009-2541
dc.identifier.issn
1872-6836
dc.identifier.other
10.1016/j.chemgeo.2022.121076
en_US
dc.identifier.uri
http://hdl.handle.net/20.500.11850/572984
dc.identifier.doi
10.3929/ethz-b-000572984
dc.description.abstract
Tracing the deep geological water cycle requires knowledge of the hydrogen isotope systematics between and within hydrous materials. For quenched hydrous alkali-silicate melts, hydrogen NMR reveals a distinct heterogeneity in the distribution of stable hydrogen isotopes (D, H) within the silicate tetrahedral network, where deuterons concentrate strongly in network regions that are associated with alkali cations. Previous hydrogen NMR studies performed in the sodium tetrasilicate system (Na2O x 4SiO2, NS4) with a 1:1 D2O/H2O ratio showed on average 1300 ‰ deuterium enrichment in the alkali-associated network, but the effect on varying bulk D2O/H2O ratios on this intramolecular isotope effect remained unconstrained. Experiments in the hydrous sodium tetrasilicate system with 8 wt% bulk water and varying bulk D2O/H2O ratios were performed at 1400 °C and 1.5 GPa. It is found that both hydrogen isotopes preferably partition into the silicate network that is associated with alkali ions. The partitioning is always stronger for the deuterated than for the protonated hydrous species. The relative enrichment of deuterium over protium in the alkali-associated network, i.e., the intramolecular isotope effect, correlates positively with the D2O/H2O bulk ratio of the hydrous NS4 system. Modeled for natural deuterium abundance (D/H near 1.56 × 10−4), a 1.4-fold (c. 340 ‰) deuterium enrichment in the alkali-associated silicate network is predicted. The partitioning model further predicts a positive correlation between the bulk water content of the silicate melt and the intramolecular deuterium partitioning into the alkali-associated silicate network. Such heterogeneities may explain the magnitude and direction of hydrogen isotope fractionation in hydrous silicate melts coexisting with silicate-saturated fluids. As such, this intramolecular isotope effect appears to be an effective mechanism for deuterium separation, particularly in hydrous magmatic settings, such as subduction zones.
en_US
dc.format
application/pdf
en_US
dc.language.iso
en
en_US
dc.publisher
Elsevier
en_US
dc.rights.uri
http://creativecommons.org/licenses/by/4.0/
dc.subject
Silicate melt
en_US
dc.subject
Deep water cycle
en_US
dc.subject
Volatiles
en_US
dc.subject
Hydrogen isotopes
en_US
dc.subject
NMR spectroscopy
en_US
dc.title
Intramolecular hydrogen isotope exchange inside silicate melts – The effect of deuterium concentration
en_US
dc.type
Journal Article
dc.rights.license
Creative Commons Attribution 4.0 International
dc.date.published
2022-08-30
ethz.journal.title
Chemical Geology
ethz.journal.volume
610
en_US
ethz.journal.abbreviated
Chem. geol.
ethz.pages.start
121076
en_US
ethz.size
10 p.
en_US
ethz.version.deposit
publishedVersion
en_US
ethz.identifier.wos
ethz.identifier.scopus
ethz.publication.place
Amsterdam
en_US
ethz.publication.status
published
en_US
ethz.date.deposited
2022-09-28T06:48:45Z
ethz.source
SCOPUS
ethz.eth
yes
en_US
ethz.availability
Open access
en_US
ethz.rosetta.installDate
2022-09-28T12:16:28Z
ethz.rosetta.lastUpdated
2023-02-07T06:49:21Z
ethz.rosetta.versionExported
true
ethz.COinS
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