The margin of Chryse Planitia, Mars, contains >10⁵ kilometer‐scale mesas, buttes, and plateaus (“mounds”), many of which are found in and around Oxia Planum, the ExoMars 2022 Rover landing site. Despite this, their origins and evolution are unknown. We have analyzed the morphologies and morphometries of 14,386 individual mounds to: (1) classify them based on their geomorphology; (2) constrain when they formed based on their stratigraphic and spatial relationships; and (3) develop hypotheses for their geological history. The mounds are classified as compound mounds, mesas, clustered mounds, and hills. Mound heights show that their elevations above the plains tend to a maximum height of 500 m. We interpret this as the thickness of a previously continuous layer that extended several hundred kilometers from the southern highlands into Chryse Planitia. Stratigraphy constrains the deposition of this layer to the Early‐Middle Noachian, correlatable to the phyllosilicate‐bearing strata of Mawrth Vallis, with similar layering also observable in some mounds, suggesting a genetic relationship. The mounds sometimes occur in circular arrangements, interpreted as an association with buried impact structures. We propose that the mounds formed through differential erosion after the premound layer was indurated by mineralization from groundwater in areas superposing underlying crustal weaknesses, for example, at buried crater margins. The subsequent differential erosion of this layer preferentially removed areas unaffected by this induration in the Late Noachian‐Early Hesperian leaving the mound population seen at present. These features present accessible three‐dimensional exposures of ancient layered rocks, and so are exciting targets for future study.

中文翻译：

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火星南部Chryse Planitia的地形学，形态学和孤立地貌分布

Chryse Planitia（火星）的边缘包含> 10 ⁵千米级的台地，山丘和高原（“土丘”），其中许多位于ExiaMars 2022 Rover登陆点Oxia Planum及其周围。尽管如此，它们的起源和进化仍是未知的。我们分析了14,386个单独丘的形态和形态，以：（1）根据它们的地貌对其进行分类；（2）根据地层和空间关系限制它们的形成；（3）为其地质历史提出假设。土墩分为复合土墩，台地，成簇土墩和丘陵。土墩的高度表明，它们在平原上方的高度趋向于最大高度为500 m。我们将其解释为先前连续的层的厚度，该层从南部高地延伸到Chryse Planitia已有数百公里。地层学将这一层的沉积限制在早中的诺亚纪时期，这与莫夫·瓦利斯（Mawrth Vallis）的页硅酸盐岩地层有关，在某些土丘中也可观察到类似的分层，表明成因关系。土墩有时以圆形排列的形式出现，被解释为与掩埋的冲击结构有关。我们建议，在叠加潜在地壳弱点的区域（例如，埋在火山口边缘的区域）中，由于地下水的矿化作用而使前丘层被硬化后，通过差异侵蚀形成的丘陵。随后该层的不同侵蚀优先去除了Noachian-Hesperian晚期硬结影响的区域，从而留下了目前可见的土丘种群。