Evidence for widespread glaciation in Arcadia Planitia, Mars

Viscous flow features, including lobate debris aprons and lineated valley fill, are common ice-related features found across the mid-latitudes of Mars. These features are commonly found along the dichotomy boundary and around massifs where snow and ice can accumulate and flow to topographic lows during periods of higher obliquity. We have identified and mapped glacial-related features reminiscent of lineated valley fill and lobate debris aprons in the lower mid-latitudes of Arcadia Planitia based on morphology, thermal infrared reflectance, thermal inertia, and subsurface radar reflections. Three sinuous features show surface morphologies and supporting spectral properties indicative of massive buried ice, including distinct boundaries, arcuate and linear banding, deep radar reflections, dielectric constants similar to water-ice, expanded secondary craters, and proximity to lobate debris aprons. We interpret the sinuous and lobate features of Arcadia Planitia to be buried debris-covered glaciers formed during higher obliquity periods in Mars’ recent past. These sinuous features appear to be channelized ice that once flowed but currently reside in a flat-lying region. Although their origin is unclear, we consider an ice stream or subglacial history due to a lack of obvious topographic dependence. The abundant evidence of widespread near-surface ice in a flat-lying lower mid-latitude region of Mars makes Arcadia Planitia a potentially favorable site for future missions due to the high potential for in situ resource utilization.

粘性流特征（viscous flow features）是火星中纬度区域广泛分布的一类常见与冰相关的地貌，其中包括瓣状碎屑岩床（lobate debris aprons）与条纹谷充填物（lineated valley fill）。这类地貌常分布于火星二分边界（dichotomy boundary）沿线以及地块（massifs）周边——在火星自转轴倾角较高的时期，积雪与冰体可在此堆积并向地形低洼处流动。本研究团队基于形态学、热红外反射率、热惯量（thermal inertia）与地下雷达反射信号，在阿卡迪亚平原（Arcadia Planitia）的低中纬度区域识别并测绘了一类类似条纹谷充填物与瓣状碎屑岩床的冰川相关地貌。三处蜿蜒特征（sinuous features）展现出指示巨量埋藏冰（massive buried ice）的表面形态与配套光谱特性，包括清晰的边界、弧形与线性条带、强雷达反射信号、与水冰相近的介电常数（dielectric constants）、扩张的次生陨石坑（secondary craters），以及与瓣状碎屑岩床的邻近性。我们认为，阿卡迪亚平原的蜿蜒与瓣状地貌为近期火星高倾角时期形成的被碎屑覆盖的埋藏冰川（debris-covered glaciers）。这类蜿蜒特征看似为曾经发生流动的渠化冰（channelized ice），目前却赋存于平坦区域。尽管其起源尚不明确，但由于缺乏明显的地形依赖性，我们推测其具有冰流（ice stream）或冰下演化的历史。火星平坦低中纬度区域广泛分布近地表冰的大量证据，使得阿卡迪亚平原成为未来深空探测任务的潜在优选着陆点——因其具备极高的原位资源利用（in situ resource utilization）潜力。