Extraction of water and solutes from argillaceous rocks for geochemical characterisation: methods, processes and current understanding

This paper summarises the results of a comprehensive critical review, initiated by the OECD/NEA "Clay Club," of the extraction techniques available to obtain water, and solutes from argillaceous rocks. The paper focuses on the mechanisms involved in the extraction processes, the consequences on the isotopic and chemical composition of the extracted pore water and the attempts made to reconstruct its original composition. Finally, it provides some examples of reliable techniques and information, as a function of the purpose of the geochemical study.