Unraveling the Geologic History of Miranda’s Inverness Corona

Miranda is the only icy body whose surface is known to contain the enigmatic features called corona—ovoid to trapezoidal areas of deformation. In this work, we seek to constrain potential formation mechanisms for Inverness Corona, the youngest known region on Miranda (Kirchoff et al., 2022). To do this, we created the first detailed geologic map of Inverness, enabling the creation of a stratigraphic column of the order of events that formed this region. We employed a previously published Digital Elevation Model (DEM) of the northern region of Inverness Corona (Beddingfield et al., 2022) to analyze the spacing of features in the region, that we propose to be extensional in origin. From this, we estimate an approximate brittle ice shell thickness of 2.5-3.8 km at the time of the region’s formation, indicating that Miranda’s brittle ice shell may have been relatively thin in the geologically recent past. We propose that Inverness formed from extension driven by a rising diapir or ice-shell thickening from a recent orbital resonance with Umbriel (Ćuk et al., 2020). The Uranus Orbiter and Probe (UOP) mission is the highest priority flagship mission recommendation of the 2023-2032 Planetary Science and Astrobiology Decadal Survey. As such, we suggest measurements related to imaging, composition, gravity, and ice-shell thickness to gain an understanding of the geologic and orbital histories of the Uranian satellites, which would have implications for the evolution of the system as a whole.

米兰达（Miranda）是已知表面存在名为冕（corona）的神秘特征的唯一冰质天体——冕是呈卵状至梯形的变形区域。本研究旨在约束因弗内斯冕（Inverness Corona）的潜在形成机制，该区域是米兰达上已知最年轻的区域（Kirchoff等，2022）。为此，我们绘制了因弗内斯冕的首张详细地质图，从而能够建立该区域形成事件序列的地层柱。我们采用了先前发表的因弗内斯冕北部区域的数字高程模型（DEM）（Beddingfield等，2022），以分析该区域内特征的间距——我们认为这些特征起源于伸展作用。据此，我们估算出该区域形成时的脆性冰壳厚度约为2.5-3.8千米，这表明米兰达的脆性冰壳在地质历史近期可能相对较薄。我们提出，因弗内斯冕的形成源于底辟上升驱动的伸展作用，或源于近期与天卫二（Umbriel）的轨道共振导致的冰壳增厚（Ćuk等，2020）。天王星轨道器与探测器任务（Uranus Orbiter and Probe，UOP）是2023-2032年行星科学与天体生物学十年调查中优先级最高的旗舰任务建议。因此，我们建议开展与成像、成分、重力及冰壳厚度相关的测量，以了解天王星卫星的地质和轨道历史——这将对整个系统的演化具有重要意义。