Crustal architecture and tectonic evolution of the southernmost Río de la Plata Craton and its Neoproterozoic–Paleozoic sedimentary cover: Insights from 3D litho-constrained stochastic inversion models

Abstract

In the last decade, several models have been proposed to explain the location and geometry of the southern margin of the Archean–Paleoproterozoic Río de la Plata Craton. However, these topics and the regional distribution of the Neoproterozoic–Paleozoic sedimentary cover of the craton are still widely debated. This contribution presents a 3D litho-constrained gravity inversion model of the southern sector of the Río de la Plata Craton, based on the integration of geological, geophysical, and petrophysical data. The distribution of the Neoproterozoic–Paleozoic sedimentary cover of the region is reassessed considering a common and protracted geological history of the three morphotectonic units involved in the study area: the Tandilia System, the Claromecó Basin, and the Ventania System. Our results provide key information on the location and geometry of the southern margin of the Río de la Plata Craton that supports its relationship with the Neoproterozoic Brasiliano/Pan-African Orogeny and, subsequently, with the Paleozoic Terra Australis and Gondwanide orogenies. In this context, the Neoproterozoic basement of the Ventania System was dextrally transported from the Brasiliano/Pan-African Orogen during the late Ediacaran–early Cambrian and thrusted over the Río de la Plata Craton and its Neoproterozoic–early Paleozoic sedimentary cover during the Permian. Likewise, our 3D model also shed new insights into the orogenic mechanisms of deformation transfer from the North Patagonian Massif to the Ventania System. The deep crustal geometry determined for the latter suggests intraplate deformation, mainly due to the Permian reactivation of the boundary between the Río de la Plata Craton and the Brasiliano/Pan-African basement. This implies that the Ventania System was mechanically disconnected from the Permian orogenic front located further southwest in the North Patagonian Massif, thus challenging previous models of orogenic architecture for the region.