L'apport des mineraux opaques a l'etude des paleoalterations: Exemple de quelques sables tertiaires de haute Belgique

The study in incident light of the heavy minerals contents of some Oligocene sands in the Hautes Fagnes and the Liege regions (Belgium) clearly shows the successive stages of their weathering: a diagenetic reduction pointed out by the weathering products of ilmenite and ilmenomagnetite, a sulphurization when a lagoonal environment succeeded to the Oligocene regression, a phase of silicification and finally the oxidation of the sediment, more or less intense depending upon the local conditions.