Currently, Mars appears to be in a frozen state, with the clear majority of the planet's surface maintaining year-round sub-zero temperatures. The discovery of features consistent with landforms found in periglacial environments on Earth, suggests a recent climate history for Mars dominated by the presence of permafrost and/or freeze-thaw cycling. Landforms indicative of such periglacial activity include hummocky, polygonized, scalloped, and pitted terrains in the mid-to high-latitudes of both hemispheres. The detection of near-surface and surface ice by the Phoenix lander, excavation of ice by recent impacts, complemented by interpreted results from the SHAllow RADar (SHARAD) instrument, further unveil a landscape in the mid-latitudes enriched in subsurface ice. We report here on the landscape analysis of a region within Utopia Planitia, where we aim to assess the influence of periglacial processes in the formation of a new landform that we have dubbed ‘Decameter-scale Rimmed Depressions’ or DRDs for short. These features are small-scale depressions surrounded by a narrow rim, ranging from <1 ​m to no higher than a few metres in height. We categorized 3 different DRD morphologies: ellipse morphologies, labyrinth, and tear-drops. DRDs share many morphological similarities with so-called “brain terrain”, although unlike “brain terrain”, most of the DRDs we mapped occur on intra-crater plains and not in association with glacial flow features. The presences of isolated fully enclosed ellipse morphologies is also a notable difference. We discuss the possibility that “brain terrain” and DRDs are genetically different features, but given the similarity in morphology and geographic distribution, we find this unlikely. Thus, while we cannot rule out an origin of DRDs through periglacial sorting, we favour a process for DRD formation similar to that proposed “brain terrain”, whereby ground ice, likely in the form of buried glacial ice, underwent thermal contraction and differential degradation, resulting in the formation of the landform that we see today. DRDs thus represent a further morphological marker for the presence of ground ice in the northern plains of Mars.

目前，火星似乎处于冰冻状态，行星表面的大部分地区全年保持低于零的温度。发现与地球上冰缘环境中发现的地貌一致的特征表明，火星最近的气候历史以永久冻土和/或冻融循环的存在为主。表明这种冰缘活动的地貌包括两半球中高纬度地区的丘陵、多边形、扇形和坑洼地形。凤凰号着陆器对近地表和地表冰的探测、最近撞击对冰的挖掘，再加上浅层雷达 (SHARAD) 仪器的解释结果，进一步揭示了中纬度地区富含地下冰的景观。我们在此报告乌托邦平原内一个地区的景观分析，我们的目标是评估冰缘过程对形成新地貌的影响，我们将其称为“十米尺度的边缘洼地”或简称 DRD。这些特征是被狭窄边缘包围的小规模凹陷，高度从<1米到不高于几米。我们对 3 种不同的 DRD 形态进行了分类：椭圆形态、迷宫和泪珠。DRD 与所谓的“脑地形”有许多形态相似之处，尽管与“脑地形”不同，我们绘制的大多数 DRD 发生在火山口内平原上，与冰川流特征无关。孤立的全封闭椭圆形态的存在也是一个显着的差异。我们讨论了“大脑地形”和 DRD 是基因不同特征的可能性，但鉴于形态和地理分布的相似性，我们认为这不太可能。因此，虽然我们不能通过冰缘分选排除 DRD 的起源，但我们倾向于类似于提出的“大脑地形”的 DRD 形成过程，其中地面冰，可能以埋藏的冰川冰的形式，经历热收缩和差异降解，从而形成了我们今天所见的地貌。因此，DRD 代表了火星北部平原存在地冰的进一步形态学标记。从而形成了我们今天看到的地貌。因此，DRD 代表了火星北部平原存在地冰的进一步形态学标记。从而形成了我们今天看到的地貌。因此，DRDs 代表了火星北部平原存在地冰的进一步形态标记。