Order/disorder phase transition in cordierite and its possible relationship to the development of symplectite reaction textures in granulites
Based on a consistent set of empirical interatomic potentials, static structure energy calculations of various Al/Si configurations in the supercell of Mg-cordierite and Monte Carlo simulations the phase transition between the orthorhombic and hexagonal modifications of cordierite (Crd) is predicted...
| Main Authors: | , , , , , |
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| Format: | Journal Article |
| Published: |
Pleiades Publishing Ltd.
2007
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| Online Access: | http://hdl.handle.net/20.500.11937/12743 |
| _version_ | 1848748161808465920 |
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| author | Vinograd, V. Perchuk, L. Gerya, T. Putnis, A. Winkler, B. Gale, Julian |
| author_facet | Vinograd, V. Perchuk, L. Gerya, T. Putnis, A. Winkler, B. Gale, Julian |
| author_sort | Vinograd, V. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Based on a consistent set of empirical interatomic potentials, static structure energy calculations of various Al/Si configurations in the supercell of Mg-cordierite and Monte Carlo simulations the phase transition between the orthorhombic and hexagonal modifications of cordierite (Crd) is predicted at 1623 K. The temperature dependences of the enthalpy, entropy, and free energy of the Al/Si disorder were calculated using the method of thermodynamic integration. The simulations suggest that the commonly observed crystallization of cordierite in the disordered hexagonal form could be related to a tendency of Al to occupy T1 site, which is driven by local charge balance. The increase in the Al fraction in the T1 site over the ratio of 2/3(T1): 1/3(T2), that characterizes the ordered state, precludes formation of the domains of the orthorhombic phase. This intrinsic tendency to the crystallization of the metastable hexagonal phase could have significantly postponed the formation of the association of orthorhombic cordierite and orthopyroxene over the association of quartz and garnet in metapelites subjected to granulite facies metamorphism. The textures of local metasomatic replacement (the formation of Crd + Opx or Spr + Crd symplectites between the grains of garnet and quartz) indicate the thermodynamic instability of the association of Qtz + Grt at the moment of the metasomatic reaction. This instability could have been caused by the difficulty of equilibrium nucleation of orthorhombic cordierite. |
| first_indexed | 2025-11-14T07:00:39Z |
| format | Journal Article |
| id | curtin-20.500.11937-12743 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T07:00:39Z |
| publishDate | 2007 |
| publisher | Pleiades Publishing Ltd. |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-127432017-09-13T16:06:42Z Order/disorder phase transition in cordierite and its possible relationship to the development of symplectite reaction textures in granulites Vinograd, V. Perchuk, L. Gerya, T. Putnis, A. Winkler, B. Gale, Julian Based on a consistent set of empirical interatomic potentials, static structure energy calculations of various Al/Si configurations in the supercell of Mg-cordierite and Monte Carlo simulations the phase transition between the orthorhombic and hexagonal modifications of cordierite (Crd) is predicted at 1623 K. The temperature dependences of the enthalpy, entropy, and free energy of the Al/Si disorder were calculated using the method of thermodynamic integration. The simulations suggest that the commonly observed crystallization of cordierite in the disordered hexagonal form could be related to a tendency of Al to occupy T1 site, which is driven by local charge balance. The increase in the Al fraction in the T1 site over the ratio of 2/3(T1): 1/3(T2), that characterizes the ordered state, precludes formation of the domains of the orthorhombic phase. This intrinsic tendency to the crystallization of the metastable hexagonal phase could have significantly postponed the formation of the association of orthorhombic cordierite and orthopyroxene over the association of quartz and garnet in metapelites subjected to granulite facies metamorphism. The textures of local metasomatic replacement (the formation of Crd + Opx or Spr + Crd symplectites between the grains of garnet and quartz) indicate the thermodynamic instability of the association of Qtz + Grt at the moment of the metasomatic reaction. This instability could have been caused by the difficulty of equilibrium nucleation of orthorhombic cordierite. 2007 Journal Article http://hdl.handle.net/20.500.11937/12743 10.1134/S0869591107050013 Pleiades Publishing Ltd. fulltext |
| spellingShingle | Vinograd, V. Perchuk, L. Gerya, T. Putnis, A. Winkler, B. Gale, Julian Order/disorder phase transition in cordierite and its possible relationship to the development of symplectite reaction textures in granulites |
| title | Order/disorder phase transition in cordierite and its possible relationship to the development of symplectite reaction textures in granulites |
| title_full | Order/disorder phase transition in cordierite and its possible relationship to the development of symplectite reaction textures in granulites |
| title_fullStr | Order/disorder phase transition in cordierite and its possible relationship to the development of symplectite reaction textures in granulites |
| title_full_unstemmed | Order/disorder phase transition in cordierite and its possible relationship to the development of symplectite reaction textures in granulites |
| title_short | Order/disorder phase transition in cordierite and its possible relationship to the development of symplectite reaction textures in granulites |
| title_sort | order/disorder phase transition in cordierite and its possible relationship to the development of symplectite reaction textures in granulites |
| url | http://hdl.handle.net/20.500.11937/12743 |