Possible ice-wedge polygonisation in Utopia Planitia, Mars and its latitudinal gradient of distribution

Abstract

On Earth, ice complexes are commonplace landscapes amidst the continuous permafrost of coastal or near-coastal plains in the Arctic. Formed by the freeze-thaw cycling of water, ice complex features include: hummocky (thermokarstic) terrain, inflated or deflated by the presence of absence of excess ice; thermokarst lakes (i.e. excess ice that has thawed and pooled); alases (i.e. thermokarst basins emptied of water); and, ice-wedge polygons, often characterized by raised (iceaggraded) or lowered (ice-degraded) margins relative to the polygon centres.The origin and development of these complexes is rooted in inter-or intra-glacial pulses of temperature that engender widespread thaw, meltwater distribution and migration through the soil column (sometimes to decametres of depth), and the freeze-thaw cycling of the meltwater.The possible existence of ice-rich terrain on Mars revised by the freeze-thaw cycling of water dates back to the grainy Mariner-mission photographs of the 1960s and 1970s. However, absent of regolith samples from areas where this terrain is hypothesised, attempts to validate the ice-rich hypothesis often have ended abruptly, either with spectrometric inferences of waterequivalent hydrogen to one metre or so of depth or with "looks-like", therefore "must-be" analogies derived of Earth-based ice-complexes.In the case of small-sized Martian polygons with low-and high-centres, the similarities of form between ice and sand-wedge polygons on Earth has equivocated the reach of ice-wedge hypotheses on Mars.Here, we show that:1) The plains' terrain of our study region in Utopia Planitia (40-50 o N; 100-125 o E) displays a statistically-significant and positive (linear) correlation between the ratio of low-centred to high-centred polygons (lcps vs hcps) and a poleward latitude of distribution.2) This linear correlation would be expected, in as much as ground-ice stability increases with latitude, were the shoulders of higher-latitude lcps underlain by (aggraded) ice-wedges and those of lower-latitude hcps underlain by (degraded) ice-wedges.3) The change of polygon morphology with latitude would not be expected were the lcps and hcps underlain by sand wedges, in as much as ground-ice stability is unrelated to their aggradation or degradation. 4)Crater counts of the polygonised terrain indicate that it is less youthful than previous studies have suggested, perhaps by an order of magnitude. This attenuates the possible inconsistency between the more temperate boundary-conditions required by the formation of ice-wedge polygons and the current constraints of extreme aridity, low temperatures and low atmospheric pressure.

Martian Araneiforms: A Review

“…Titus et al, 2003) or found at depths of a few cm to meters (Bandfield & Feldman, 2008;Piqueux et al, 2019), interpreted as massive and nearly pure deposits whose origin varies as a function of unit and hemisphere (Bramson et al, 2017;Morgan et al, 2021;Schorghofer & Forget, 2012). Water ice deposits are generally associated with high thermal inertia values and are associated with patterned ground (e.g., Balme et al, 2013;Séjourné et al, 2011Séjourné et al, , 2012Soare et al, 2021).…”

“…If this is the case, the absence of spider features on exposed perennial CO 2 ice may not just be caused by the intrinsic substrate properties, but also by the optical properties of the overlying seasonal CO 2 ice. Water ice, both exposed (Bibring et al., 2004; Piqueux et al., 2008; T. Titus et al., 2003) or found at depths of a few cm to meters (Bandfield & Feldman, 2008; Piqueux et al., 2019), interpreted as massive and nearly pure deposits whose origin varies as a function of unit and hemisphere (Bramson et al., 2017; Morgan et al., 2021; Schorghofer & Forget, 2012). Water ice deposits are generally associated with high thermal inertia values and are associated with patterned ground (e.g., Balme et al., 2013; Séjourné et al., 2011, 2012; Soare et al., 2021). Both attributes point to rock‐like competent material properties, potentially not conducive to surficial scouring and the formation of spiders.…”

Planetary geomorphology

“… Lobate forms interpreted to be solifluction lobes (see section 7) (Figure 8d).  Polygonal patterned ground where the centres are lower than the margins and those margins form double-ridges implying the existence of ice wedges (Soare et al, 2021(Soare et al, , 2014 (Figure 8e).  Scalloped depressions (Soare et al, 2008) and polygon junction pits (Costard et al, 2016) were initially interpreted to be true thermokarst (i.e.…”

A billion or more years of possible periglacial/glacial cycling in Protonilus Mensae, Mars

“…Third, this would be the case especially were near-surface perchlorate brines present (e.g. Gallagher et al, 2011;Barrett et al, 2017;Soare et al, 2018Soare et al, , 2021a; also, see brine references in, e.g. Renno et al, 2009;Martinez et al, 2017;Primm et al, 2019;Chevrier et al, 2020).…”