Resumo

TURIENZO, Martín M.; DIMIERI, Luis V.; FRISICALE, María C.  e  ARAUJO, Vanesa S.. Evolution of the Andean structures at the Río Diamante region (34º40'SL): linkage between the Malargüe fold-and-thrust belt and the Cordillera Frontal. Rev. Asoc. Geol. Argent. [online]. 2010, vol.67, n.3, pp.354-368. ISSN 0004-4822.

The study of the Andean structures at the Río Diamante region and its linkage with the tertiary volcanic, subvolcanic and sedimentary rocks, allow us to propose a structural evolution for this sector of the Andes. Two basement-involved sectors with a thin-skinned sector between them form the dominant structure. At the western sector, large basement wedges related to Andean thrusts have propagated along favourable horizons in the cover generating the thrusts and folds of the thin-skinned central sector. Deformation of these sectors, that implies 10 km of shortening, took place between 14.5 Ma and 10.8 Ma, which represents an important Middle Miocene compressive event (2.7 mm/year). At the eastern sector, the absence of efficient detachments difficulted the development of basement wedges and instead a significant deformation occurred by backthrusting. Several subvolcanic bodies (10.5 Ma to 5.5 Ma) cropping out in the backthrusting area suggest that is apparent a close relationship between the magmatism and the antithetic faulting. With continuing compression, the Carrizalito fault cuts towards the surface thrusting pre-Jurassic and Mesozoic over tertiary rocks, although in the southern region it remains as a blind thrust with evidence of modern seismicity. A shortening of 4.3 km in the eastern sector was attained between 10.8 Ma and 0.5 Ma, which indicates that Andean contraction diminished during Late Miocene-Pleistocene times.

Palavras-chave : Kinematic; Andean tectonic; Basement wedges; Andes; Río Diamante.

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