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The Andes are thought to be formed through discrete contractionalstages separated by periods of little to no orogenic construction. This paper analyzesthe intervals between the main contractional phases that built the Southern CentralAndes between 35° and 37°S in order to determine whether they were characterized byneutral, contractional or extensional conditions. During an interruption in orogenesisbetween the Late Cretaceous and the Miocene shortening phases, two extensionalstages are recorded through the opening of a series of intra- and retro-arc basins. U-Pbdating of detrital zircons in a sample collected from the Los A´ ngeles unit, a synextensionalvolcano-sedimentary succession located at 35°40?S along the Chile andArgentina international border, provided a maximum depositional age of 67.1 2.4/0.9 Ma. This age, in association with evidence of regional crustal thinning, suggests apreviously unrecognized extensional phase during latest Cretaceous times. Limitedshortening succeeded this extensional event and was followed by a second extensionalepisode during late Oligocene and earliest Miocene times. While the first extensionalevent was restricted to the core of the Late Cretaceous orogen, the second episodeaffected a wide area ranging between the present forearc and retroarc areas. Astructural section across the Malargu¨e fold-thrust belt at 36°S indicates inversion ofnormal faults where extension was focused and new thrust generation in areas notaffected by extensional deformation. Our data reveal that the growth of the SouthernCentral Andes is the product of a complex alternation of contractional and extensionalphases, with inherited structures playing a role in their tectonic evolution. A comparisonwith other Cordilleran orogenic systems such as the Puna-Altiplano plateau, thenorthern Peruvian Andes and the North American Sevier-Laramide orogenic belt,suggests that extensional deformation in the Southern Central Andes responds betterto changes in plate kinematics, rather than to localized events within a continuouscontractional setting.