Please use this identifier to cite or link to this item:
http://hdl.handle.net/2122/3733
DC Field | Value | Language |
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dc.contributor.authorall | Schuessler, J.; Liebniz Universitat Hannover | en |
dc.contributor.authorall | Botcharnikov, R.; Liebniz Universitat Hannover | en |
dc.contributor.authorall | Behrens, H.; Liebniz Universitat Hannover | en |
dc.contributor.authorall | Misiti, V.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia | en |
dc.contributor.authorall | Freda, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia | en |
dc.date.accessioned | 2008-04-07T12:52:28Z | en |
dc.date.available | 2008-04-07T12:52:28Z | en |
dc.date.issued | 2008 | en |
dc.identifier.uri | http://hdl.handle.net/2122/3733 | en |
dc.description.abstract | The oxidation state of iron in hydrous ultrapotassic (phono-tephritic) melts coexisting with mixed H2O-CO2 fluids was experimentally studied at 1200 and 1250{degree sign}C and pressures from 50 to 500 MPa. The oxygen fugacity (fO2) varied from NNO-2.9 to NNO+2.6 in logfO2, relative to the Ni-NiO oxygen buffer (NNO), as imposed by external redox conditions in experimental vessels and internal variations in water activity from 0.05 to 1 inside the capsules. The iron redox state of the quenched melts was determined by colorimetric wet-chemical analysis. This analytical method was optimized to measure the Fe2+/ΣFe ratio of mg-sized samples within ±0.03 (2σ). The accuracy and precision was tested with international reference materials and with standards analyzed by other methods. The Fe2+/ΣFe ratio of the experimental glasses covered a range of 0.41 to 0.85. A small negative effect of dissolved water on Fe2+/ΣFe at given fO2 was found, consistent with the thermodynamic model of Moretti (2005). No effect of pressure and temperature on the redox state of iron was resolvable in the investigated P-T range. Compared to hydrous ferrobasaltic melts that were studied previously under similar conditions, systematically lower Fe2+/ΣFe ratios were found for the phono-tephritic melts, in particular at low oxygen fugacities. This effect is attributed to the much higher K2O contents of the phono-tephrite (7.5 compared to 0.3 wt%), but the difference in ΣFeO (7.8 wt% in the phono-tephrite and 12.9 wt% in the ferrobasalt) may have an influence as well. Comparison of the experimentally obtained relationship between logfO2 and Fe3+/Fe2+ for the studied hydrous ultrapotassic melts with commonly used empirical and thermodynamic models suggest that these models can be successfully applied to phono-tephritc melts, although such compositions were not implemented in the model calibrations. Furthermore, the new data can be used to improve the models with respect to the effects of compositional variables, such as H2O or K2O, on the redox state of iron in silicate melts. | en |
dc.language.iso | English | en |
dc.publisher.name | MINERALOGICAL SOC AMER | en |
dc.relation.ispartof | American Mineralogist | en |
dc.relation.ispartofseries | 10/93(2008) | en |
dc.subject | iron oxidation state, ferrous iron determination, oxygen fugacity, phono-tephrite, ultrapotassic hydrous silicate melt, Alban Hills, water activity | en |
dc.title | Oxidation state of iron in hydrous phono-tephritic melts | en |
dc.type | article | en |
dc.description.status | Published | en |
dc.type.QualityControl | Peer-reviewed | en |
dc.description.pagenumber | 1493-1504 | en |
dc.identifier.URL | http://www.minsocam.org/MSA/AmMin/TOC/2008/Oct08.html | en |
dc.subject.INGV | 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology | en |
dc.description.obiettivoSpecifico | 2.3. TTC - Laboratori di chimica e fisica delle rocce | en |
dc.description.journalType | JCR Journal | en |
dc.description.fulltext | open | en |
dc.contributor.author | Schuessler, J. | en |
dc.contributor.author | Botcharnikov, R. | en |
dc.contributor.author | Behrens, H. | en |
dc.contributor.author | Misiti, V. | en |
dc.contributor.author | Freda, C. | en |
dc.contributor.department | Liebniz Universitat Hannover | en |
dc.contributor.department | Liebniz Universitat Hannover | en |
dc.contributor.department | Liebniz Universitat Hannover | en |
dc.contributor.department | Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia | en |
dc.contributor.department | Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia | en |
item.openairetype | article | - |
item.cerifentitytype | Publications | - |
item.languageiso639-1 | en | - |
item.grantfulltext | open | - |
item.openairecristype | http://purl.org/coar/resource_type/c_18cf | - |
item.fulltext | With Fulltext | - |
crisitem.author.dept | Liebniz Universitat Hannover | - |
crisitem.author.dept | Institut für Mineralogie, Uni Hannover, Germany | - |
crisitem.author.dept | Liebniz Universitat Hannover | - |
crisitem.author.dept | Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione Roma1, Roma, Italia | - |
crisitem.author.dept | Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione Roma1, Roma, Italia | - |
crisitem.author.orcid | 0000-0002-6151-7789 | - |
crisitem.author.orcid | 0000-0002-2320-8096 | - |
crisitem.author.parentorg | Istituto Nazionale di Geofisica e Vulcanologia | - |
crisitem.author.parentorg | Istituto Nazionale di Geofisica e Vulcanologia | - |
crisitem.classification.parent | 04. Solid Earth | - |
crisitem.department.parentorg | Istituto Nazionale di Geofisica e Vulcanologia | - |
crisitem.department.parentorg | Istituto Nazionale di Geofisica e Vulcanologia | - |
Appears in Collections: | Article published / in press |
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schuessler et al.pdf | 768.89 kB | Adobe PDF | View/Open |
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