Multi-episodic bauxitization in a karstic and rifted setting (Early Cretaceous, South-western Iberian Basin, Spain): An interdisciplinary approach

Abstract

Bauxitic deposits serve as valuable sedimentary archives, offering insights into paleoclimatic, paleogeographic, and geodynamic processes over time. A multidisciplinary analysis of bauxitic deposits in the Cuenca Domain (Iberian Ranges, central Spain) aims to reconstruct their genesis in the framework of the geological evolution of this region during the Late Jurassic-Early Cretaceous rift episode. The bauxitic deposits preserve paleosol profiles that show multi-episodic processes of sedimentation, reworking, erosion, pedogenesis, and bauxitization, reflecting a landscape's dynamics that was strongly influenced by episodic tectonic activity. The presence of book-type kaolinite aggregates, ferruginous pisoids and ooids, and soil horizons provide evidence of in situ bauxitization. On the other hand, the presence of fractured pisoids and ooids, brecciated textures, and bauxitic C horizons also points to some degree of reworking. Authigenic boehmite suggests optimal conditions for bauxitization, whereas ferruginous crusts and peds at the top of the deposits point to a later ferruginization phase. A subsequent kaolinitization episode, probably driven by the infiltration of silica-rich fluids, is also recorded. By integrating stratigraphic, sedimentological, and mineralogical data, a succession of genetic stages in bauxite development has been identified, shaped by the tectonic evolution of the area. The proposed stratigraphic and pedogenetic model enhances the regional significance of the findings and enables a refined chronology of its tectonic evolution. The results highlight the potential of bauxitic materials, not only as paleoclimatic indicators but also as robust tools for reconstructing paleogeographic and tectonic conditions in complex settings where the sedimentary record is apparently homogeneous and extremely incomplete.