Resumo

BILMES, Andrés; D´ELIA, Leandro; VEIGA, Gonzalo D  e  FRANZESE, Juan R. Relleno intermontano en el Antepaís Fragmentado Patagónico: evolución neógena de la Cuenca de Gastre. Rev. Asoc. Geol. Argent. [online]. 2014, vol.71, n.3, pp.311-330. ISSN 0004-4822.

The Gastre Basin is one of the largest intermontane basins of the Patagonian Broken Foreland. It is oblique to the Andean chain and located more than 550 km east of the Andean trench. It was originated by reverse faulting and inversion of pre-existing normal faults during the Middle-Miocene, allowing the preservation of a continuous sedimentary record up to the present. Stratigraphic, sedimentologic and structural observations indicate a pre-tectonic, syn-tectonic and post-tectonic evolution stage. The pre-tectonic stage (late Lower Miocene) was related to a combination of a flexural subsidence event in the foreland in response to the tectonic activity in the fold and thrust belts, and the influence of explosive volcanism over low-gradient sedimentary environments. The syn-tectonic stage (Middle Miocene,) is marked by the contractional deformation event in which the Gastre Basin was structurally configured. During this stage, basin compartmentalization associated with shallow lacustrine systems occurred. The post-tectonic stage (Middle Miocene - Pliocene) involves the post-deformational deposits characterized by deep lacustrine systems under explosive volcanism influence as well as the alluvial and braided fluvial system. During this stage an abrupt decreasing of the volcaniclastic supply, which characterized the Miocene Northpatagonian successions, occurred. This was combined with a major climatic change developed in the Middle Miocene that corresponds with the change from the optimal climate to the aridity period in response to the Andean uplift.

Palavras-chave : Patagonian broken foreland; Intermontane basin; Miocene; Collón Curá Formation; Allocyclic factors.

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