Resumen

RAMOS, Victor A. Evolución de la cuenca golfo San Jorge: su estructuración y régimen tectónico. Rev. Asoc. Geol. Argent. [online]. 2015, vol.72, n.1, pp.12-20. ISSN 0004-4822.

The Golfo de San Jorge Basin is a basin developed to the east of the first foothills of the Patagonian Cordillera between 44° and 48° S latitude, which has a complex geological history. Its basement was structured by a large compressive strain associated with a Neopaleozoic collision, followed by important extensional periods linked to the Jurassic opening of the Weddell Sea. An extensional fracturing, associated with the opening of the South Atlantic in the Late Jurassic, is superimposed in an almost orthogonal orientation. An extensional regime prevailed during the Early Cretaceous, this time produced by subduction with extension governed by the absolute motion of the South American plate. The onset of compression in the Late Cretaceous controlled the tectonic load subsidence of the continental deposits of the Chubut Group in a foreland basin. This basin, with a highly segmented basement and no confined margins also favored the existence of extensional faults with subparallel orientation to the main compressive stress during the Late Cretaceous. This system prevailed during the early Paleogene, with a conspicuous stress rotation, culminating in the Oligocene with an incipient primary extension associated with an intraplate alkali basaltic volcanism. This was associated with a decrease in the absolute displacement of the South American plate. The structure of the basin obtained the present geometry in the Neogene with the final development of the Bernárdides fold and thrust belt.

Palabras clave : Patagonia; Extension; Compression; Weddell Sea; South Atlantic.

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