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Transport multicomposant en milieu poreux : application à l'évolution d'un système carbonaté

Abstract : This work deals with spatial-time evolution of a carbonate system due to transport and chemical processes. In this study, carbonate diagenesis is focused on calcitization, i.e. the aragonite to calcite transformation of Porites coral skeletons.
The comprehension of these phenomena is apprehended by a multi-field approach relevant from both geology (1) and porous media physics (2).
1. Geology - Various stages of calcitization are investigated in a series of Pleistocene and Holocene fossil corals, sampled in uplifted terraces of New-Caledonia, Wallis and Futuna, and Vanuatu (South-West Pacific). Diagenetic cements are observed and characterized at a fine scale by various imagery techniques (X Ray Diffraction, Optical Microscopy, Cathodoluminescence Imagery, Raman Spectroscopy, Scanning Electron Microscopy, Electron Microprobe...) in order to discriminate the different phases of calcitization and to identify the involved mechanisms.
2. Porous media physics - With the aim explaining structural heterogeneities observed at the “thin section scale”, a model of multicomponent reactive transport is developed at the microscopic scale including the significant processes of the coral diagenesis (tracer diffusion, migration due to the species charge, adsorption/desorption, kinetic and/ or thermodynamic chemical reactions). Preliminary 1D direct simulations are presented and discussed in terms of the most significant microscopic processes for calcite cementation. This type of numerical experiments can be used as the basis of a tractable upscaling procedure, which allow taking into account additional parameters (in particular several scales of description...). This is illustrated for a digitized 3D sample of Porites subjected to an idealized process of reaction transport.
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https://tel.archives-ouvertes.fr/tel-00110963
Contributor : Cécile Rabier <>
Submitted on : Thursday, November 2, 2006 - 5:08:03 PM
Last modification on : Thursday, January 11, 2018 - 6:20:34 AM
Long-term archiving on: : Tuesday, April 6, 2010 - 6:30:24 PM

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  • HAL Id : tel-00110963, version 1

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Cécile Rabier. Transport multicomposant en milieu poreux : application à l'évolution d'un système carbonaté. Hydrologie. Université Sciences et Technologies - Bordeaux I, 2005. Français. ⟨tel-00110963⟩

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