Large asymmetric polar scarps on Planum Australe, Mars : characterization and evolution

• Main Authors: Grima, C., Costard, F., Kofman, W., Saint-Bézar, B., Servain, A., Rémy, F., Mouginot, J., Herique, A., Seu, R.
• Other Authors: Institut de Planétologie et d'Astrophysique de Grenoble (IPAG ), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS), Interactions et dynamique des environnements de surface (IDES), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales Toulouse (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Department of Earth System Science Irvine (ESS), University of California Irvine (UCI), University of California-University of California, Dipartimento INFOCOM Roma, Università degli Studi di Roma "La Sapienza" = Sapienza University Rome
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2011
• Subjects: [SDU.STU.PL]Sciences of the Universe [physics]/Earth Sciences/Planetology; Ice Sheet
• Online Access: https://hal.archives-ouvertes.fr/hal-00572377

International audience Numerous scarps with similar characteristics have been observed in the polar layered deposits of Planum Australe, Mars. They are referred to as LAPSs (for Large Asymmetric Polar Scarps) because of their typical cross-section featuring a trough between a straight slope on one side with outcrops of layered deposits and a convex slope on the other side without any outcrops. These LAPSs are restricted to the outlying region of Ultimi Lobe. Topographic data, optical images, and subsurface radar observations have been analyzed and compared to produce a complete morphologic and stratigraphic description of these scarps. In all, 167 LAPS-like features have been identified. All have similar dimensions and characteristics and appear to be deep depressions in the ice. The polar deposits have an average thickness of 1 km in this region and the LAPS depressions commonly reach half of that thickness. Subsurface data indicate that the depressions could reach bedrock at certain locations. Many surface features of the polar deposits of Mars are considered to be consequences of depositional and/or erosion processes. We propose a mechanical failure of the ice for the LAPSs origin, given the striking similarities in shape and size they show with rollover anticlines above listric faults commonly observed as a crustal extension mode on Earth. This tectonic scenario would imply a substantial outward sliding of the polar deposits in the region of Ultimi Lobe and a low basal shear stress. No information is available to determine whether such a system could be active at present. Confirmation of the "mechanical failure" hypothesis of these LAPSs on Mars is of major importance as it could be a macro-expression of fundamental differences between ice-sheet behavior under martian and terrestrial conditions. (C) 2010 Elsevier Inc. All rights reserved.