The periglacial landscape of Utopia Planitia, Mars

Post by Antoine Séjourné, Univ. Paris-Sud XI, CNRS, Laboratoire IDES, France

On Earth, periglacial regions underlined by continuous and ice-rich permafrost are found in areas of Northern Canada and Siberia These areas are very sensitive to abrupt climate-changes (Murton, 2001). The ice-rich permafrost has a unique assemblage of landforms, some of which are signatures of climate change (Image 1).

On Earth one example are the thermokarst lakes that have resulted from extensive thawing of permafrost following global warming during the Holocene (Czudek and Demek, 1970).  Freeze-thaw cycles of the permafrost produce ice-wedge polygons (Washburn, 1973). Localized melting of ice-wedges at the junction of the polygons induces the formation of small ponds of surface water (Washburn, 1973).

Image 1

Image 1: Assemblage of periglacial landforms in Canada (aerial photo 2009 A. Séjourné)

The Utopia Planitia region, located in the northern mid-latitudes of Mars contains relatively young landforms (<10 Myr) that are possibly periglacial (Image 2).

The scalloped depressions (100-1,000 m in diameter) are proposed to be the result of sublimation or melting of ground-ice (Morgenstern et al., 2007; Soare et al., 2008). There is a current debate about the development of the depressions, specifically whether they expand equatorward during high obliquity periods, or poleward during low obliquity periods of Mars (Lefort et al., 2009; Séjourné et al., 2011).

The Martian polygons (100 m in diameter) are thought to be formed by thermal-cracking of a permafrost and filling of the cracks with sand or ice (Lefort et al., 2009; Séjourné et al., 2011). Associated elongated pits (10-100 m in diam.) are observed at the junction of some polygons (Image 2). They are proposed to be due to sublimation or melting of ground-ice (Morgenstern et al., 2007; Soare et al., 2008).

Image 2

Image 2: Possible periglacial landforms of Utopia Planitia on Mars (HiRISE image PSP_002202_2250)

The landforms in Utopia Planitia are similar in morphology and scale to the periglacial landforms on Earth (Séjourné et al., 2011). They are part of a landform assemblage indicating an ice-rich permafrost. This permafrost was degraded during a relatively recent obliquity-change of Mars inducing the formation of depressions and pits. The Utopia Planitia landforms described here are probably a marker of a recent climate change that occurred on Mars.

References:

Czudek, T. , Demek , J., 1970. Thermokarst in Siberia and its influence on the development of lowland relief. Quaternary Research 1, 103-20.

Lefort, A., P. S. Russell, N. Thomas, A. S. McEwen, C. M. Dundas, and R. L. Kirk, 2009. Observations of periglacial landforms in Utopia Planitia with the High Resolution Imaging Science Experiment (HiRISE). J. Geophys. Res., 114, E04005.

Morgenstern, A., E. Hauber, D. Reiss, S. van Gasselt, G. Grosse, Schirrmeister, L., 2007. Deposition and degradation of a volatile-rich layer in Utopia Planitia and implications for climate history on Mars. J. Geophys. Res., 112, E06010.

Murton, J.B., 2001. Thermokarst sediments and sedimentary structures, Tuktoyaktuk Coastlands, western Arctic Canada, Global and Planetary Change 28, 175-192.

Séjourné, A., Costard, F., Gargani, J., Soare, R., Fedorov, A., Marmo, C., 2011. Scalloped depressions and small-sized polygons in western utopia planitia, mars: A new formation hypothesis. Planetary and Space Science 59 (5-6), 412–422.

Soare, R. J., G. R. Osinski, Roehm C. L., 2008. Thermokarst lakes and ponds on Mars in the very recent (late Amazonian) past. Earth Planet. Sci. Lett., 272(1– 2), 382– 393.

Washburn, A.L., 1973. Periglacial Processes and Environments. New York: St Martin’s Press. 318 pp.

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