Evolution of the Paleozoic Claromecó Basin (Argentina) and geodynamic implications for the southwestern margin of Gondwana: Insights from isostatic, gravimetric and magnetometric models

The evolution of the Paleozoic Claromecó Basin is intimately related to contemporaneous tectonic events in the Sierras Australes and Patagonia (Argentina). These deformation and tectonomagmatic processes record, in turn, the evolution of the southwestern margin of Gondwana during the Paleozoic, which is still controversial and has been alternatively interpreted as the result of different subduction-related, extensional or collisional events. The Claromecó Basin, thus, comprises a key area to evaluate possible mechanisms of subsidence, which could have allowed creating the necessary accommodation space for the sedimentary pile. For this purpose, 2D isostatic flexural models, 2.5D magnetic and gravimetric models, 1D backstripping and 3D gravity inversion were carried out in this work. Results suggest that the Claromecó Basin could have initially developed during back-arc extension in a retreating subduction boundary, followed by a period of anomalous subsidence associated with the load exerted by an ancient subducted slab. Dynamic subsidence, thus, played a major role during this period, resulting from subduction processes along the proto-Pacific margin of Gondwana. Later on, the basin evolution was dominated by the load constructed by the deformation that generated the Sierras Australes.