Study on smectite-to-illite transformation mechanism

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Study on smectite-to-illite transformation mechanism, using the core samples IT-2 from the Kakkonda geothermal field, has been successfully completed and the results have been published in five papers of international and national journals. In this year, we worked on motmorillonite-to-beidellite transformation at Bouillante geothermal field, Guadeloupe as an application of our current model of smectite-to-illite transformation mechanism. Detailed XRD, FTIR and chemical analyses clearly demonstrated a transition from montmorillonite to beidellite with increasing depth and temperature via interstratification of the two layers. However this transition was not explained by a thermally controlled beidellitization but control of solution composition related to the precipitation of clays, based on the carbon and oxygen isotopes data analysis. This conclusion is reasonably accepted from the viewpoint of our current model of smectite-to-illite transformation mechanism. This result has been submitted to an article of American Mineralogist co-authored with French colleagues.In the next step, it is important to understand the precipitation dynamics of clay minerals in water-rock interaction. It is not easy that experimental works undertakes to understand the behavior of silicate ions in solution. Instead of crystallization of silicates, thus, we started working on crystallization process of iron oxyhydroxide minerals, especially focusing on understanding of the role of anions in the formation of FeOOH minerals. We have interested results on this subject and published two papers.