Title: Study of ice-rich permafrost: a high-resolution regional study and palaeoclimatic implications
Funding: PNP and CNES HRSC
Principal investigator: F. Costard
GEOPS staff involved: A. Séjourné, F. Costard, S. Bouley, F. Schmidt
Partners: JAP Rodriguez (Univ. Tucson), R. Soare, (Dawson, Canada)
The planet Mars possesses a cryosphere in the form of a polar cap and ice in the ground, particularly in the plains of the northern hemisphere. The GRS gamma-ray spectrometer and the Phoenix lander have detected this subsurface ice (< 1 m), and numerous cryosphere features (polygons, thermokarst depressions, etc.) and glacial features (glaciers, etc.) have been observed. However, this cryosphere (origin, quantity, distribution) as well as the deposits of the northern plains and their links to recent global climate changes (< 100 Ma) remain largely unknown. We carried out standardised mapping and geomorphological analysis of the northern plains of Mars. It brought together several teams across Europe with expertise in planetary geology (Paris-Saclay, Open University, Dublin, Berlin, DLR, Wroclaw). The aim was to produce a large-scale, high-resolution map of periglacial and glacial landforms using the latest satellite data from three basins in the northern plains (Acidalia, Utopia, Arcadia). The project enabled the reconstruction of the recent geological and climatic history (< 50 Ma) of the northern plains (Ramsdale et al., 2018, 2019; Orgel et al., 2019; Séjourné et al., 2019). In particular, we demonstrated that the structures were associated within a periglacial landscape similar to that of Siberia, featuring ice-rich permafrost formed during a previous glacial period, and that this permafrost must have contained >50% ice (Séjourné et al., 2012). Subsequently, this permafrost was degraded during a period of regional or global warming on Mars similar to the present-day Arctic, forming depressions through the sublimation of the permafrost ice (Séjourné et al., 2011). This work is continuing in collaboration with R. Soare (Dawson College, CA) on the detection of possible ice layers in Utopia (publication by Soare et al. 2025, Icarus).