Genesis of Czech bentonites related to their use in engineered barriers for nuclear waste disposal

摘要

Genetic types of smectite-rich clays reflect processes of their formation and composition of parent rocks. The genesis also significantly affect smectites' stability in geological environment and their technical (physical and other) properties applicable during their use. This study aims to give a basic overview of genetic types of smectite-rich clays in the Czech Republic, and to investigate variation of their properties significant for nuclear waste disposal. Bentonite is commonly understood as a weathered residual rock' composed almost entirely of clay minerals from the smectite family (mainly montmorillonite). According to the geological understanding of their genesis, the bentonites are formed by devitrification and chemical alteration of igneous materials usually tuffs or volcanic ash. This process occurs at the place of original volcanic eruption and is not accompanied by any significant transport of weathered material to another sedimentary basin.