Kinematic evolution of the Malargüe fold-and-thrust belt at the Río Diamante (34º40’ S.L.), Southern Andes of Argentina.

MARTÍN TURIENZO; LUIS DIMIERI

Colorado College, Usa.

Taller; Integrated Solid Earth Sciences Summer School; 2008

ISES -- Integrated Solid Earth Sciences

The Malargüe fold-and-thrust belt is a thick-skinned belt in central-western Argentina developed during the Andean orogeny, related to the subduction between the oceanic Nazca and continental South American plates. The basement is mainly composed of pre-jurassic igneous rocks that are covered by Mesozoic marine and continental sediments of the Neuquén basin. Neogene volcanic activity and sedimentation contemporaneously with the mountain building allow us to infer the relative ages of major structures. Based on detailed field mapping, seismic and well information, three balanced structural cross-sections were made resulting an average shortening of 14.2 km (24%) for basement and cover rocks (Turienzo, 2008). Dating of pre and post tectonic volcanic and subvolcanic rocks (Baldauf, 1992; Giambiagi et al., 2005) allow us to postulate that the structures were significantly active from around 14.8 Ma to 2 Ma, which suggests a rate of shortening equal to 1.1 mm/year.