Resumo

GHIGLIONE, Matías C. et al. Structure andevolution of the austral basin fold-thrust belt, Southern Patagonian Andes. Rev. Asoc. Geol. Argent. [online]. 2009, vol.65, n.1, pp.215-226. ISSN 0004-4822.

This study focuseson the evolution of the Southern Patagonian Andes fold-thrust belt and theadjacent non-deformed foreland of the Austral basin between 49°45' and52°00'SL. This sector involves mainly Late Cretaceous sequences of the firstregressive cycle (Lago Viedma Cycle) of the Austral basin foreland stage, andCampanian to Paleogene sequences associated with tectonic uplift of its westernboundary. From a stratigraphic-sedimentary point of view, a first-orderincrease in the fillthickness and depth to the basement exists from north tosouth including the presence of deeper depositional environments in the samedirection. Furthermore, there are strong along-strike variations in width andlateral position of the structural domains following the same trend. Based uponprevious interpretations, is concluded that the distribution of extensionaldepocenters from the early extensional phase of the basin controlled theseimportant sedimentary and structural N-S contrasts. Furthermore, in ourpresented model, East-west oriented transition zones are interpreted asaccommodation zones separating synrift sub-basins.

Palavras-chave : Austral basin; Foreland basin; Cretaceous; Extensional depocenters.

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