Salient and recess development in the Agrio-Alumine fold and thrust belt. Influence of a pre-Andean foreland obstacle

DANIEL L. YAGUPSKY; EZEQUIEL GARCÍA MORABITO; MAXIMILIANO NAIPAUER; CARLA M. TERRIZZANO; ERNESTO O. CRISTALLINI; VICTOR A. RAMOS

Santiago de Chile

Congreso; GeoSur 2013; 2013

The Agrio-Aluminé fold and thrust belt on theeastern fank of the Andes between 37º and 40º30?S showsa significant along-strike variation in width which defines acurved geometry. Diferential forelanward propagation ofboth portions delineates a wider northern portion(Chihuidos salient) and a narrower southern portion thatbecomes a recess (Laguna Blanca recess). Both sectorsexhibit different degrees of exhumation, accompained bynotable morphological, topographic, and structuralchanges.In the southern segment, the lateral growth of the FTB wasinhibited by the presence of a pre-Andean east-westoriented regional feature known as the Huincul High. Thecombination of structural data and detrital zircon ages of itsexposed protion, demostrates that the Huincul High wasalready uplifted by the time of inception of Andeandeformation. Therefore, it would have acted as a transverseforeland obstacle that inhibited the lateral growth of theAndean belt, increasing uplift and deformation at itsadjacent back zone.This setting suggest a higher pre-deformationalsedimentary sequence involved in the Agrio FTB, and theinteraction of the Aluminé FTB with the Huincul High, asfirst-order variables in originating a curved geometry of theFTB.