Abstract
Weathered and fresh samples of Sri Lancan rocks (metamorphic) were collected from various localities and analysed for major elements by XRF method (Rigaku, KG-X System, Japan). The amount of water was found by ignation method.
The XRF results were used for various weathering indices to find the most suitable chemical index of weathering applicable to Sri Lanka. The values of each index for all samples were obtained and their variations were compared.
Out of eight different chemical indices of weathering Ruxton's Ratio, Product Index and Weathering Potential Index are most suitable to find the variations of the degree of weathering in the Sri Lankan rocks. Measuring of H2O(+) amount of rock material is a good and reliable method to find the degree of weathering to a certain extent.
Résumé
Des échantillons de roches métamorphiques altérées et saines ont été prélevés dans différents points du Sri Lanka et l'analyse de leurs principaux éléments a été réalisée par spectrométrie de fluorescence X.
Les résultats obtenus ont permis d'établir différents indices d'altération en vue de choisir le mieux adapté pour le Sri Lanka.
Parmi 8 indices chimiques différents le «Ruxton's ratio», le «Product Index» et le «Weathering potential index» sont ceux qui rendent le mieux compte du degré d'altération des roches étudiées. La mesure de la teneur en eau des roches peut également donner des indications intéressantes sur le degré d'altération.
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Jayawardena, U.d.S., Izawa, E. Application of present indices of chemical weathering for precambrian metamorphic rocks in Sri Lanka. Bulletin of the International Association of Engineering Geology 49, 55–61 (1994). https://doi.org/10.1007/BF02595001
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DOI: https://doi.org/10.1007/BF02595001