Stratigraphical and morphological evidence for pingo genesis in the Cerberus plains

‘Rootless’ debris cones (or pseudocraters) occur in platy, patterned ground throughout the Cerberus plains of Mars and are thought to represent the products of explosive magma–ice interaction [Lanagan et al., 2001. Geophys. Res. Lett. 28, 2365–2368; Fagents et al., 2002. In: Smellie, J.L., Chapman, M.G. (Eds.), Volcano–Ice Interaction on Earth and Mars. In: Geol. Soc. Spec. Publ., vol. 202, pp. 295–317]. Requiring lava and water interspersed, they are central to theories of multiple magmatic and aqueous flood events [Burr et al., 2002. Icarus 159, 53–73; Berman, D.C., Hartmann, W.K., 2002. Icarus 159, 1–17] and widespread sheet volcanism [Keszthelyi et al., 2000. J. Geophys. Res. 105, 15027–15049] in the region during the late Amazonian (a region reported to have been occupied by water bodies ranging from lakes to oceans [Scott et al., 1995. Map of Mars showing channels and possible paleolake basins. USGS Miscellaneous Investigations Series, Map I-2461 (1:30,000,000)]). The nature of the platy substrate is the subject of debate, with evidence given for lava [Keszthelyi et al., 2000. J. Geophys. Res. 105, 15027–15049; Plescia, J.B., 2003. Icarus 164, 79–95] and ice [Brakenridge, G.R., 1993. Lunar Planet. Sci. XXIV (Part 1), 175–176; Rice et al., 2002. Lunar Planet. Sci. XXXIII. Abstract #2026; Murray et al., 2005. Nature 434, 352–355]. The superposition relationships of cones and platy deposits in the channels of the Athabasca Valles precludes a magmatic origin, indicating later formation as permafrost mounds (or ‘pingos’), with implications for geologically recent flood volcanism, age constraints on young surfaces and recent climate change on Mars.