Article révisé par les pairs
Résumé : Low temperature neoformed REE phosphates (monazites) have been discovered in the Neogene cryptokarsts from Southern Belgium. These minerals are intimately associated with kaolinite, at the karst wall. They range from a few nanometers to a few tens of micrometers in size. The mobilization of the trace elements as well as the processes that resulted in their trapping in monazites, together with the neoformed clays (halloysite, kaolinite) were discussed through a detailed geochemical investigation. Keywords: Monazite, Weathering, Kaolinite, Rare earth elements, Cryptokarst. © Académie des Sciences.