In situ infiltration-precipitation processes in some rock systems

Abstract

We carry out a chemical treatment (acidization or basification) of typical rock specimens in-situ, and characterize the emerging pattern resulting from the infiltration-precipitation scenario. Galena and limestone samples were treated with sulfuric acid, while pyrite was reacted with sodium hydroxide. Various infiltration techniques were employed, after selection of the most feasible method for each rock separately. The patterns of anglesite (PbSO4), anhydrite (CaSO4) and goethite (FeOOH) deposition presented different alteration modes of the bare rock textures. Among the three deposited minerals, only the anhydrite (CaSO4) displayed a band stratification. The formation of a Liesegang pattern in the rock of highest porosity indicates a plausible correlation between the band formation and a minimum porosity requirement. A banded rock of compact texture could then be formed by a cementation mechanism, governing the long time evolution of the rock. © 2023, The Author(s), under exclusive licence to Science Press and Institute of Geochemistry, CAS and Springer-Verlag GmbH Germany, part of Springer Nature.