Possible open-system (hydraulic) pingos in and around the Argyre impact region of Mars

We report the observation of possible (hydraulic) open-system pingos (OSPs) at the mid latitudes (similar to 37 degrees S) in and around the Argyre impact-basin. OSPs are perennial (water)-ice cored mounds; they originate and evolve in periglacial and pro-glacial landscapes on Earth where intra- or subpermafrost water under hydraulic/artesian pressure uplifts localised sections of surface or near-surface permafrost that then freezes in-situ. We invoke three lines of evidence in support of our analogue-based interpretation: (1) similarities of shape, size and summit traits between terrestrial OSPs and the Martian mounds; (2) clustered distribution and the slope-side location of the mounds, consistent with terrestrial permafrost-environments where OSPs are found; and, (3) spatially-associated landforms putatively indicative of periglacial and glacial processes on Mars that characterise OSP landscapes on Earth. This article presents five OSP candidate-locations and nests these mound locations within a new geological map of the Argyre impact-basin and margins. It also presents three periglacial hypotheses about the possible origin of the water required to develop the mounds. Alternative (non-periglacial) formation-hypotheses also are considered; however, we show that their robustness is not equal to that of the periglacial ones. (C) 2014 Elsevier B.V. All rights reserved.