(U-Th)/He Geochronology Constraints on Lateritic Duricrust Formation on the Guiana Shield oleh C. Ansart, C. Quantin, D. Calmels, T. Allard, J. Y. Roig, R. Coueffe, B. Heller, B. Heller, R. Pinna-Jamme, J. Nouet, S. Reguer, D. Vantelon, C. Gautheron