土卫六极地地形地貌制图：约束表面过程和景观演变
Geomorphologic Mapping of Titan's Polar Terrains: Constraining Surface Processes and Landscape Evolution
摘要：
我们提出了土卫六的极地地形地貌图。该地图是由卡西尼合成孔径雷达和成像科学子系统成像产品以及测高、SARTopo和雷达测量地形数据集组合而成的。在结合图像与地形数据，我们的地貌图揭示了一个地层序列，从中我们推断单元之间的过程相互作用。在绘制具有相同地貌单元的两极地区时，我们得出结论，形成北极地区地形的过程也形成了我们在南极观察到的景观。均匀的SAR暗平原被解释为沉积矿床，并以适度切割的高地为界。这些平原包含最高密度的填充和空湖洼地和峡谷。这些单元不整合地覆盖在基底岩石上，基底岩石在两极的不同海拔处以山脉和SAR明亮的解剖地形露头。然后，所有这些单元都被向海洋倾斜的表层单元叠加，这表明随后沉积物的陆上搬运。从嵌入的空洞洼地和流入海洋的峡谷的深度估计，SAR黑暗平原的厚度必须超过600米，尽管两极的厚度可能有所不同。在每个极地地区的最低海拔处，都有大片的海洋，目前北部充满了液态甲烷/乙烷，南部则是空的。大型平原沉积物和周围的山坡可能是以前广阔的极地海洋的残留地貌，其中较大的液体可能允许可溶性和不溶性沉积物的持续积累，可能形成分层沉积物。再加上地壳的垂直运动，所形成的地层将具有不同的溶解度和抗侵蚀性。
英文摘要：
We present a geomorphologic map of Titan's polar terrains. The map was generated from a combination of Cassini Synthetic Aperture Radar (SAR) and Imaging Science Subsystem imaging products, as well as altimetry, SARTopo and radargrammetry topographic datasets. In combining imagery with topographic data, our geomorphologic map reveals a stratigraphic sequence from which we infer process interactions between units. In mapping both polar regions with the same geomorphologic units, we conclude that processes that formed the terrains of the north polar region also acted to form the landscape we observe at the south. Uniform, SAR-dark plains are interpreted as sedimentary deposits, and are bounded by moderately dissected uplands. These plains contain the highest density of filled and empty lake depressions, and canyons. These units unconformably overlay a basement rock that outcrops as mountains and SAR-bright dissected terrains at various elevations across both poles. All these units are then superposed by surficial units that slope towards the seas, suggestive of subsequent overland transport of sediment. From estimates of the depths of the embedded empty depressions and canyons that drain into the seas, the SAR-dark plains must be >600 m thick in places, though the thickness may vary across the poles. At the lowest elevations of each polar region, there are large seas, which are currently liquid methane/ethane filled at the north and empty at the south. The large plains deposits and the surrounding hillslopes may represent remnant landforms that are a result of previously vast polar oceans, where larger liquid bodies may have allowed for a sustained accumulation of soluble and insoluble sediments, potentially forming layered sedimentary deposits. Coupled with vertical crustal movements, the resulting layers would be of varying solubilities and erosional resistances.
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