Skip to Main content Skip to Navigation
Theses

Contrôles thermodynamiques et cinétiques des états d'oxydation du fer dans les liquides silicatés magmatiques : Expérimentation, Modélisation, Applications et simulations.

Abstract : Terrestrial magmas display a large range of redox conditions, which reflect several interplays taking place at various steps of magmas evolution. The iron redox ratio of these magmas is commonly used as an indicator of the redox conditions (fO2). In order to improve the interpretation of magmas redox signatures, the behavior of iron in silicate melts is constrained through several experimental and theoretical approaches:
1- Modeling of redox equilibria in silicate liquids:
Ø Analyze of the bibliographic data base
Ø The data base is extended toward oxidized and hydrated systems through appropriate experiments
Ø Modeling of the thermodynamic properties of ferrous and ferric iron
From a practical point of view, the thermodynamic model we propose allows to estimate pre-eruptive T or fO2 from natural magnetite-glass assemblages. Moreover, Fe3+/Fe2+ equilibria can be calculated for a wide range of compositions and conditions. Some applications and the precision of this method are detailed.
2- Constraints on the kinetics of iron oxidation-reduction in hydrous melts:
Ø Experimental studies
Ø Modeling
Different mechanisms of iron-hydrogen redox interactions are identified. As results, we suggested that H2 exchanges seem not able to significantly modify the redox signature of a magma stored in the crust. Rather, internal equilibria as magnetite-liquid are most likely to control the T-fO2 evolution of such magma. In contrast, simulations of percolation and H exchange between a small volume of basalt and a peridotite suggested an increase of fO2 sufficient to explain the redox features of calc-alcaline suites.
Complete list of metadata

https://tel.archives-ouvertes.fr/tel-00002091
Contributor : Nathalie Pothier <>
Submitted on : Monday, December 9, 2002 - 11:44:32 AM
Last modification on : Thursday, March 5, 2020 - 6:49:19 PM
Long-term archiving on: : Friday, April 2, 2010 - 6:24:03 PM

Identifiers

  • HAL Id : tel-00002091, version 1

Citation

Fabrice Gaillard. Contrôles thermodynamiques et cinétiques des états d'oxydation du fer dans les liquides silicatés magmatiques : Expérimentation, Modélisation, Applications et simulations.. Géologie appliquée. Université d'Orléans, 2001. Français. ⟨tel-00002091⟩

Share

Metrics

Record views

486

Files downloads

3826