Geomorphic expression of the southern Central Andes forebulge (37°S, Argentina)

Authors

  • Bertrand Nivière,

    Corresponding author
    1. LFCR - UMR 5150/CNRS/Total/University of Pau, IPRA, Pau Cedex, France
    • Correspondence: Bertrand Nivière, LFCR - UMR 5150/CNRS/Total/University of Pau, IPRA, BP 1155, F-64013 Pau Cedex, France. Tel.: +33 559 40 74 22; fax: +33 559 40 74 15; e-mail: bertrand.niviere@univ-pau.fr

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  • Grégoire Messager,

    1. LFCR - UMR 5150/CNRS/Total/University of Pau, IPRA, Pau Cedex, France
    2. Group of Dynamics of the Lithosphere Group, Institute of Earth Sciences “Jaume Almera”, CSIC, Barcelona, Spain
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  • Sébastien Carretier,

    1. GET - UMR 5563/CNRS/UPS/IRD/CNES, University of Toulouse, Toulouse, France
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  • Pierre Lacan

    1. LFCR - UMR 5150/CNRS/Total/University of Pau, IPRA, Pau Cedex, France
    Current affiliation:
    1. Centro de Geociencias, Universidad Nacional Autónoma de México, Blvd. Juriquilla, Juriquilla, Mexico
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Abstract

We present a geomorphologic analysis of an east-west transect located east of the southern Andes of Argentina (~37°S). We observe a succession of zones that underwent erosion and deposition during the Pleistocene. If the proximal Andean foothills are incised, a proximal depozone receives sediments feeding the megafan of the Rio Colorado on the Chadileuvú plain. More distally, the abandoned palaeo-valleys and bending of the valley floors reflect a localized uplift. Further to the east, another depozone corresponds to the Pampa Deprimida lowland. This pattern is consistent with the presence of a classical flexural geometry of the lithosphere. The distal uplift of the foreland corresponds in terms of location, length (150 km) and amplitude (240 m) to the Andean forebulge modelled by a geophysical approach. In this study, we identify the morphological imprint of this bulge and show its effect on the fluvial activity.

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