Ferricretes as a source of continental oolitic ironstones in northern Sudan

Abstract

In northern Sudan lateritic ferricretes and oolitic ironstones occur, the latter in both fluvial and marine sediments. Oolites and ferricretes display a close similarity such as a similar geochemical enrichment spectrum including V, which is a key element to distinguish ferricretes from simple ferribands formed in hydromorphic soils. In addition, elevated Al content of goethite, ferricrete-derived nuclei of ooids, and the existence of continental oolites as link between weathering crusts and marine deposits point to a lateritic source of sedimentary iron oolites.