gisement d’uranium de type roll-front

CONT: Genèse des gisements d’uranium de type roll-front […] Les concentrations de type roll-front constituent le type majeur de gisement d’uranium en contexte sédimentaire et repré­sentent une part très importante des réserves mondiales à bas coût.
OBS: Au Sud Texas, le gisement uranifère de Panna Maria, de type «roll», se serait formé selon ces processus biogéniques [...]

CONT: The subeconomic Dorchester deposit in New Brunswick evidently has a higher grade linear or curvilinear zone in contact with barren pyrite near an oxidation-reduction ""front"" and a lower grade zone away from the ""front."" Although incompletely documented, this morphology is similar to that of uranium roll-front deposits.
OBS: The resulting sedimentary rocks are most important as hosts for uranium deposits, which are generally termed Colorado Plateau type after their best known occurrences, where they are also known as roll-front type after their form and mode of deposition.