Résumé
Comparison between the minerals (determined by FTIR spectroscopy) and pollen content of lacustrine sediments from the Salitre area (Brazil) shows that the variations of the mineral content are indicators of regional or local environmental changes. An opposite trend between the forest cover and the detrital content of sediments is observed during the Pleistocene lacustrine episode. FTIR spectroscopy allows the detection of a sedimentary hiatus outlined by a large change in the mineral content; it also emphasizes the abrupt nature of some changes of the vegetation cover which, without adequate datings, could have been misinterpreted as a sedimentary hiatus.