CONICET | Buscador de Institutos y Recursos Humanos

Although cratons have long been recognized as an important part of continental tectonic processes, we still have much to learnabout their structural features and their relation to the genesis of basins, sedimentary thickness distributions, fold and thrustbelts and surface processes. Contributing to a better knowledge of the crustal state and configuration of the southernmostpart of the Río de la Plata Craton, could shed light on the still controversial tectonic processes, which were responsible forthe deformation of the southwestern margin of Gondwana during the Late Paleozoic. In particular, the deformation and upliftof the Sierras Australes, which are part of the Claromecó Basin (Buenos Aires, Argentina), would be closely related to thecrustal structure of the southern limit of the Río de la Plata Craton. Therefore, it is of crucial importance to investigate thepossible 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 evolutionof the study area. For this purpose, we developed a 3D lithospheric-scale density model integrating various data, suchas geological information, global gravity models, well data (thicknesses and lithologies), seismic tomography data (Mohodepth), and pre-existing 3D density models of the Colorado Basin. Our model includes layers of sediments, crystalline crustand lithospheric mantle and therefore predicts the thickness variation of the upper and lower crust in the study area and of themain sedimentary sequences infilling the basins. Moreover, by analysing the model results, we propose a tentative locationof the southern limit of the Río de la Plata Craton and its possible tectonic relationship with transfer zones identified in theAtlantic platform southwards. Our results suggest that the southern boundary of the craton is located along the northernmostlimit of the Colorado Basin, which is in contrast with the boundary proposed in previous works. Therefore, we propose thatthe Colorado Basin rifting process could have occurred along this weakness domain.