The magmatic rocks of the Nefza district located in the NW part of Tunisia belong to a Neogene volcanic complex. It includes fresh rhyodacites weathered into kaolinite and/or halloysite, and nontronite. Chemical analyses of rhyodacites compared to the nontronite phase reveal an evolution in the composition in term of loss in Na, Ca, K. The values of CIW (Chemical Index of Weathering) and the AI index (Alteration Index of Ishikawa) show that the rhyodacite experienced chemical changes due to the leaching of the fresh rocks by meteoric and hydrothermal waters.
|Pages (de - à)||178-194|
|journal||European Journal of Scientific Research|
|Numéro de publication||2|
|Etat de la publication||Publié - mai 2014|