Compositional heterogeneities within Europa's ice shell likely impact the dynamics and habitability of the ice and subsurface ocean, but the total inventory and distribution of impurities within the shell are unknown. In sea ice on Earth, the thermochemical environment at the ice‐ocean interface governs impurity entrainment into the ice. Here, we simulate Europa's ice‐ocean interface and bound the impurity load (1.053–14.72 g/kg [parts per thousand weight percent, or ppt] bulk ice shell salinity) and bulk salinity profile of the ice shell. We derive constitutive equations that predict ice composition as a function of the ice shell thermal gradient and ocean composition. We show that evolving solidification rates of the ocean and hydrologic features within the shell produce compositional variations (ice bulk salinities of 5–50% of the ocean salinity) that can affect the material properties of the ice. As the shell thickens, less salt is entrained at the ice‐ocean interface, which implies Europa's ice shell is compositionally homogeneous below ~1 km. Conversely, the solidification of water filled fractures or lenses introduces substantial compositional variations within the ice shell, creating gradients in mechanical and thermal properties within the ice shell that could help initiate and sustain geological activity. Our results suggest that ocean materials entrained within Europa's ice shell affect the formation of geologic terrain and that these structures could be confirmed by planned spacecraft observations.

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欧罗巴冰壳内海洋杂质的夹带和动力学

欧罗巴冰壳内的成分异质性可能会影响冰和地下海洋的动力学和可居住性，但壳内杂质的总存量和分布尚不清楚。在地球上的海冰中，冰海界面处的热化学环境控制着杂质夹带进入冰中。在这里，我们模拟了欧罗巴的冰海界面，并限制了冰壳的杂质负荷（1.053–14.72 g / kg [千分之几，ppt]的散装冰壳盐度）和散装盐度分布。我们得出本构方程，该方程预测了冰成分随冰壳热梯度和海洋成分的变化。我们表明，不断发展的海洋凝固速度和壳内的水文特征会产生成分变化（冰块盐度为海洋盐度的5–50％），这会影响冰的物质特性。随着壳层变厚，冰-海洋界面夹带的盐分减少，这意味着欧罗巴的冰壳在〜1 km以下的成分均匀。相反，充满水的裂缝或晶状体的凝固会在冰壳内引入大量的成分变化，从而在冰壳内产生机械和热学特性的梯度，从而有助于启动和维持地质活动。我们的结果表明，欧罗巴内部夹带的海洋物质