The mechanism of cation and oxygen isotope exchange in alkali feldspars under hydrothermal conditions
The mechanism of re-equilibration of albite in a hydrothermal fluid has been investigated experimentally using natural albite crystals in an aqueous KCl solution enriched in 18O at 600°C and 2 kbars pressure. The reaction is pseudomorphic and produces a rim of K-feldspar with a sharp interface on a...
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| Format: | Journal Article |
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Springer
2009
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| Online Access: | http://hdl.handle.net/20.500.11937/44338 |
| _version_ | 1848756971902074880 |
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| author | Niedermeier, D. Putnis, Andrew Geisler, T. Golla-Schindler, U. Putnis, Christine |
| author_facet | Niedermeier, D. Putnis, Andrew Geisler, T. Golla-Schindler, U. Putnis, Christine |
| author_sort | Niedermeier, D. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | The mechanism of re-equilibration of albite in a hydrothermal fluid has been investigated experimentally using natural albite crystals in an aqueous KCl solution enriched in 18O at 600°C and 2 kbars pressure. The reaction is pseudomorphic and produces a rim of K-feldspar with a sharp interface on a nanoscale which moves into the parent albite with increasing reaction time. Transmission electron microscopy (TEM) diffraction contrast and X-ray powder diffraction (XRD) show that the K-feldspar has a very high defect concentration and a disordered Al, Si distribution, compared to the parent albite. Raman spectroscopy shows a frequency shift of the Si-O-Si bending vibration from ~476 cm-1 in K-feldspar formed in normal 16O aqueous solution to ~457 cm-1 in the K-feldspar formed in 18O-enriched solution, reflecting a mass-related frequency shift due to a high enrichment of 18O in the K-feldspar silicate framework. Raman mapping of the spatial distribution of the frequency shift, and hence 18O content, compared with major element distribution maps, show a 1:1 correspondence between the reaction rim formed by the replacement of albite by K-feldspar, and the oxygen isotope re-equilibration. The textural and chemical characteristics as well as the kinetics of the replacement of albite by K-feldspar are consistent with an interface-coupled dissolution-reprecipitation mechanism. © Springer-Verlag 2008. |
| first_indexed | 2025-11-14T09:20:41Z |
| format | Journal Article |
| id | curtin-20.500.11937-44338 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T09:20:41Z |
| publishDate | 2009 |
| publisher | Springer |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-443382017-09-13T14:29:23Z The mechanism of cation and oxygen isotope exchange in alkali feldspars under hydrothermal conditions Niedermeier, D. Putnis, Andrew Geisler, T. Golla-Schindler, U. Putnis, Christine The mechanism of re-equilibration of albite in a hydrothermal fluid has been investigated experimentally using natural albite crystals in an aqueous KCl solution enriched in 18O at 600°C and 2 kbars pressure. The reaction is pseudomorphic and produces a rim of K-feldspar with a sharp interface on a nanoscale which moves into the parent albite with increasing reaction time. Transmission electron microscopy (TEM) diffraction contrast and X-ray powder diffraction (XRD) show that the K-feldspar has a very high defect concentration and a disordered Al, Si distribution, compared to the parent albite. Raman spectroscopy shows a frequency shift of the Si-O-Si bending vibration from ~476 cm-1 in K-feldspar formed in normal 16O aqueous solution to ~457 cm-1 in the K-feldspar formed in 18O-enriched solution, reflecting a mass-related frequency shift due to a high enrichment of 18O in the K-feldspar silicate framework. Raman mapping of the spatial distribution of the frequency shift, and hence 18O content, compared with major element distribution maps, show a 1:1 correspondence between the reaction rim formed by the replacement of albite by K-feldspar, and the oxygen isotope re-equilibration. The textural and chemical characteristics as well as the kinetics of the replacement of albite by K-feldspar are consistent with an interface-coupled dissolution-reprecipitation mechanism. © Springer-Verlag 2008. 2009 Journal Article http://hdl.handle.net/20.500.11937/44338 10.1007/s00410-008-0320-2 Springer restricted |
| spellingShingle | Niedermeier, D. Putnis, Andrew Geisler, T. Golla-Schindler, U. Putnis, Christine The mechanism of cation and oxygen isotope exchange in alkali feldspars under hydrothermal conditions |
| title | The mechanism of cation and oxygen isotope exchange in alkali feldspars under hydrothermal conditions |
| title_full | The mechanism of cation and oxygen isotope exchange in alkali feldspars under hydrothermal conditions |
| title_fullStr | The mechanism of cation and oxygen isotope exchange in alkali feldspars under hydrothermal conditions |
| title_full_unstemmed | The mechanism of cation and oxygen isotope exchange in alkali feldspars under hydrothermal conditions |
| title_short | The mechanism of cation and oxygen isotope exchange in alkali feldspars under hydrothermal conditions |
| title_sort | mechanism of cation and oxygen isotope exchange in alkali feldspars under hydrothermal conditions |
| url | http://hdl.handle.net/20.500.11937/44338 |