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A. P. Rossi, A. Chicarro (European Space Agency, ESTEC Research and Scientific Support Department, Noordwijk, The Netherlands), V. Huvenna (Challenger Division for Seafloor Processes, National Oceanography Centre, Southampton, United Kingdom), J. P. Henriet (Renard Centre of Marine Geology, Department of Geology and Soil Science, Ghent University, Belgium), S. Di Lorenzo (International Research School of Planetary Sciences, Universite d'Annunzio, Pescara, Italy), G. Neukum (Institut fur Geologische Wissenschaften, Freie Univ. Berlin, Germany), HRSC Co-Investigator Team
Martian chaotic terrains have some morphological resemblance with certain terrestrial submarine slope failures [1]. We are comparing a few chaos areas on Mars with an ancient slope failure in the Porcupine Basin, offshore SW Ireland [2]. Disrupted terrains (chaos) occur extensively on Mars, even if most strictly named chaos are concentrated in the outflow channels source region, close to the Eastern part of Valles Marineris canyon system. Mesas in Martian chaos areas are usually up to a few tens of km wide, whereas knobs are usually from a few hundred meters to a few km. Instead, blocks in the Porcupine slope failure are up to a few hundred meters wide. The blocks (or mesas) in Porcupine slope failure occupy an average of about 42% of the area. The percentage of undisrupted mesas however varies across the slope failure. Preliminary measurements in Aureum and Hydaspis chaos on Mars show comparable but slightly lower percentage of preserved mesas (25-30%). Locally in chaotic terrain-like areas such as the area north of Deuteronilus Mensae, the percentage of preserved blocks is around 15%, possibly due to further degradation and erosion of the mesas. Fluidization possibly occurs on both Martian chaotic terrains and in this terrestrial submarine failure. It is not clear yet whether basal sliding, present in the Porcupine Basin, has occurred in certain Martian chaotic terrains, and therefore we are using HRSC data to provide constraints. Multiple processes, such as rapid fluidization and sapping, could have produced polygonal morphologies on Mars. The Porcupine Basin slope failure could be of help in understanding the mechanism of chaos formation on Mars.
References: [1] Nummedal, D. and Prior D. B., 1981, Icarus 45, 77-86. [2] Huvenne, V.A.I., Croker, P.F. & Henriet, J. P., 2002, Terra Nova, 14, 33-40.
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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.