CONICET | Buscador de Institutos y Recursos Humanos

Contributing to a better knowledge of the crustal state and configuration of the southernmost part of the Río de la Plata Craton (RPC), could shed light into the, still controversial, tectonic processes which were responsible for the deformation of the southwestern margin of Gondwana during the Late Paleozoic. In particular, the deformation and uplift of the Sierras Australes, which are part of the Claromecó Basin (Buenos Aires, Argentina), would be closely related to the crustal structure of the southern limit of RPC. Therefore, it is of crucial importance to investigate the possible existence of crustal heterogeneities underneath the Claromecó Basin, the Sierras Australes and the Colorado Basin which can be related to structural features and weakness zones that could have played a major role in the tectonic evolution of the study area. For this purpose, we developed a lithospheric scale 3D density model integrating various data, such as geological information (thicknesses, outcrops distribution, measured densities, etc), global models (EIGEN 6c4 for gravity data, GEBCO for bathymetry), well data (thicknesses and lithologies), seismic tomographies (Moho depth), and pre-existing 3D density models of the Colorado Basin. Our model includes layers of sediments, crystalline crust and lithospheric mantle and therefore predicts the thickness variation of the upper and lower crust in the study area and of the sedimentary sequences infilling the basins. Moreover, by analysing the model results, we propose a tentative location of the southern limit of the RPC and its possible tectonic relationship with transfer zones identified in the Atlantic platform southwards. Our results suggest that the southern boundary of the RPC is located along the northernmost limit of the Colorado Basin which is in contrast with the boundary proposed in previous works.

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