CONICET | Buscador de Institutos y Recursos Humanos

Sedimentary basins located at the marginsof continents act as the final base level for continental-scale catchments that are sometimeslocated thousands of kilometers away from thebasin, and this condition of exceptionally longsediment transfer zones is probably reinforced insupercontinents, such as Gondwana. One of themost prominent marine basins in southwesternGondwana during the Jurassic and Early Cretaceouswas the Neuquén Basin (west-centralArgentina), but its role as a sediment repositoryof far-flung source areas has not been extensivelyconsidered. This contribution provides the firstdetailed detrital-zircon U-Pb geochronology ofthe Valanginian?Hauterivian Pilmatué Memberof the Agrio Formation, which is combined withsedimentology and paleogeographic reconstructionsof the unit within the Neuquén Basin for abetter understanding of the fluvial delivery systems.Our detrital-zircon signatures suggest thatTriassic?Permian zircon populations were probablysourced from the adjacent western sector of theNorth Patagonian Massif, whereas Early Jurassic,Cambrian, Ordovician, and Proterozoic grains weremost likely derived from farther east, in the easternsector of the North Patagonian Massif, as well aspresently remote terranes such as the Saldania Beltin southern Africa. We thus propose a Valanginian?Hauterivian longitudinal delivery system that,starting in the mid-continent region of southwesternGondwana and by effective sorting, wasbringing fine-grained or finer caliber sand to theNeuquén Basin shoreline. This delivery system wasprobably active (though not necessarily continuously)from Early Jurassic to Early Cretaceous untilfinally coming to an end during the opening of theSouth Atlantic Ocean in the latest Early Cretaceous.