New experimental approach to study aqueous alteration of amorphous silicates at low reaction rates

Understanding the kinetics of silicate alteration in aqueous media is central to the study of oceanic hydrothermal systems, nuclear glass durability or carbonaceous asteroids from which chondrites are coming. We present a new experimental approach in combination with an integrated analytical protocol designed to study alteration processes at low temperatures (50%) and H2 formation, whose quantifications are crucial to understand terrestrial serpentinization processes. Interfacial precipitation–dissolution seems to be the rate controlling mechanisms. In addition, we investigated a crystallized film reacted at 190°C (2h), which transformation rate is ten times slower than that of the amorphous silicate but is nevertheless readily observable. This approach can be used to understand alteration in terrestrial and extraterrestrial samples. In particular, we reproduced several features observed in carbonaceous chondrites (amorphous and oxidized hydrated silicates) and show that, at 90°C, alteration may be faster than usually considered. It shou