Varas Muriel, María JosefaMolina Ballesteros, Eloy2025-12-192025-12-192004Varas-Muriel, M.J., Molina-Ballesteros, E. The role of porosity in the development of authigenic dolomite and palygorskite. An example in siliceous sandstones of continental origin in Western Spain. Int J Earth Sci (Geol Rundsch) 93, 132–143 (2004). https://doi.org/10.1007/s00531-003-0373-41437-325410.1007/s00531-003-0373-4https://hdl.handle.net/20.500.14352/129465Fondo FEDER (1FD97–0417) grant (1996–99) Project “CS” 12/98During the Tertiary, the Hercynian basement of the Iberian Peninsula was uneven due to Alpine tectonism which led to the development of a set of horsts and grabens forming its main geological structure. One of these grabens is the Ciudad Rodrigo Basin, located close to the Portuguese border. The south-western margin of this graben is filled with arkosic sandstones of continental origin that, once deposited, underwent important low-grade diagenetic processes related to the surface processes. The main diagenetic processes were hydrolysis, replacement by carbonate, and argillization to palygorskite. These three processes led to the differentiation of three main levels within the outcrops studied: (1) the Lower Level, where the original clayey sandstone outcrops, displaying fairly hydromorphic traits; (2) the Middle Level, where part of the clayey matrix has been replaced by dolomitic carbonate; and (3) the Upper Level, where palygorskite is the new neoformed clay. The change in porosity seems to have been the controlling factor, since it governs the dynamics of the solutions inside the rocks. These conditions changed from being diffusion-driven, at the start of the diagenesis, to flow-driven as porosity increased.engjournal article1437-3262https://doi.org/10.1007/s00531-003-0373-4restricted access552(460-15)549(460-15)DolomitePalygorskiteDiagenesisSandstonesContinental basinWestern SpainMineralogía (Geología)Petrología2506.14 Petrología Sedimentaria2506.11 Mineralogía