Chemical weathering processes in the 0-10 m of the critical zone developed on the Tégulines clay formation (Aube, France)

Abstract : Interactions between clayrock, atmosphere and hydrosphere induce mineralogical, chemical, pore water composition, and also petrophysical changes in the clay formation. The Lower Cretaceous Tégulines clay formation is an aquitard outcropping near Brienne-le-Chateau (north-eastern France) that Andra has investigated in the context of repository for low level radioactive waste. During the first drilling campaign, a multi-disciplinary approach highlighted the development of a critical zone (CZ) on Tégulines clay to depths of 20-25 m, with a highly reactive zone at depths of 10-12 m [2]. In this work, the main mineral and organic matter reactivities are presented as well as associated chemical weathering processes concerning the first 0-10 meters in which root network develops.