The 'Infracambrian System' in the southwestern margin of Gondwana, southern South America

Abstract

AbstractThe classical definition of ‘Infracambrian’ that refers strictly to sequences of Proterozoic age is not applicable in southwestern Gondwana. In this paper the term ‘Infracambrian’ is used to define the sequences deposited during the Pampean orogenic cycle, which extends until the Cambrian period.A classification of Infracambrian basins is proposed based on location, level of preservation and perceived petroleum potential. Only the eastern basins of the South American plate have potentially significant exploration potential.Two Neoproterozoic petroleum systems have been identified in the eastern basins: a Riphean system, developed on the western margin of the San Francisco Craton, in the San Francisco Basin of Brazil; and a Vendian system, developed on the eastern margin of the Amazonia–Río de la Plata cratons, in the Corumbá Basin of Brazil and Paraguay. The Riphean system is reportedly proven by a well test drilled by Petrobras. An active Vendian petroleum system is proven by the presence of oil seeps within fractured limestones. A Vendian petroleum system is proposed for the Claromecó Basin of Argentina based on the correlation of the Vendian and Riphean sequences.