Etude de deux nouvelles méthodes de géochronométrie : datation de formations carbonatées par la spectrométrie gamma du déséquilibre de la famille de l'uranium ; datation R.P.E. de l'émail dentaire fossile uranifère

First, the U-serie disequilibrium dating method was re-examined using non-destructive y-spectrometry. A new low-background (< 10 ppb U- equivalent) Ge-HP y- spectrometer has been used to date travertine with small U-content (~ 0,1 ppm) and low (< 5%) Th/U , content, by comparison with old-limestone yspectra. Second, a new ESR dating method has been developped using fossil dental enamel whith is rich in U-content (10 - 100 ppm). Both methods were applied to Arago Cave (Tautavel, France) : - with an Ionium-age of 120 ka (10%), the upper travertine seems to have been set up during the Riss-deglaciation period. - the high ( ~ 50%) Th/U-content samples of the intermediate travertine are undatable. - the ESR-age of EQUUS mosbachensis enamel is 400 ka (10%) for the G-soil of Arago. XXI H. erectus, and 600 ka (10%) for the Q-soil above (- 1 m) of the lower travertlne of which Io-age is older than 350 ka.