Pleistocene deformation of the Malargüe fold–thrust belt from structural modelling and geochronology of syntectonic sedimentation

Abstract

We report uplift and shortening rates from a late Neogene–Pleistocene deformation stage of the frontal fold–thrust belt and adjacent wedge-top in the Principal Cordillera of the southern Central Andes (latitude 33–39°S). A structural model is presented based on integration of surface field data and subsurface 2D seismic sections. Shortening, uplift and sedimentation rates were calculated from different steps of kinematic modelling. Our structural interpretations and modelling are integrated with new detrital zircon U–Pb geochronology to define a previously overlooked Pleistocene period of orogenic shortening and syntectonic sedimentation in the Malargüe basin. This task was possible as a result of the dating of three samples yielding ages between ∼12 and 1 Ma obtained from a 900 m deep well located in the foreland. From stratigraphic correlations, our data record an active Plio-Pleistocene wedge-top depozone coeval with retreat of the volcanism, and the emplacement of retroarc basalts. Structural modelling, together with detrital zircon U–Pb provenance data, registers shortening producing a foredeep to wedge-top Plio-Pleistocene transition, adjusting and completing the knowledge of the frontal fold–thrust belt and foreland basin in the southern Central Andes. Supplementary material: Supplementary tables are available at https://doi.org/10.6084/m9.figshare.c.7033425