In addition to representing omission surfaces important for sequence stratigraphic analyses, paleosols and subaerial exposure features provide important insights into terrestrial processes and climate. This study of Miocene paleosols in the Madrid Basin by Bustillo et al. addresses the formation of three different uranium-rich calcrete-silcrete profiles to understand the processes and environments involved in their formation and the mechanisms involved in the fixation of uranium in surficial environments. The study integrates macromorphological, micromorphological, and geochemical observations to demonstrate the importance of roots in the formation of the profiles and in the concentration of uranium. The data illustrate interesting processes, such as contemporaneous calcitization and silicification in the pedogenic vadose environment, intense rhizoturbation and rooting, and uranium enrichment. These insights provide a conceptual model for processes in uranium-rich pedogenic and meteoric environments.
Root calcretes and uranium-bearing silcretes atsedimentary discontinuities in the Miocene of the Madrid Basin (Toledo, Spain) by M. Ángeles Bustillo, Chloé Plet, and Ana M. Alonso-Zarza