The highly modified surface of Europa's ice shell hides a global, salty ocean that may hold conditions favorable for life, and cycles in the ice shell likely impact those conditions by allowing material transfer between the surface and subsurface ocean. The Galileo spacecraft observed a number of young geologic features that indicated Europa's ice shell was recently or presently active, including lenticulae. Lenticulae, a collection of quasi‐elliptically shaped surface disruptions, have been suggested to form above relatively small bodies of water (∼10 km diameter) emplaced in the ice shell as shallow as 1 km below the surface. Here, we use numerical models to quantify the longevity of small bodies of water in Europa's ice shell and explore their chemical evolution to understand how shallow water impacts the composition of the ice shell and regional surface geology over time. We find that lenticulae are more geologically transient than previously described, and that if the reservoirs contain salts, up to meters‐thick layers of salt may precipitate during the solidification process. Our results imply that, if depressions are the first signs of liquid water emplaced in the ice shell, lenticulae may be actively forming at present day, suggesting liquid water may still be present in Europa's shallow ice which could form water plumes and affect its habitability.

中文翻译：

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欧罗巴冰壳中小的浅水域的热化学演化

欧罗巴冰壳高度修饰的表面掩盖了一个全球咸海，可能拥有有利于生命的条件，并且冰壳中的循环可能通过允许物质在表层和地下海洋之间转移而影响这些条件。在伽利略航天器观察到许多年轻的地质特征，表明欧罗巴的冰壳最近或目前处于活动状态，包括小毛孔。扁豆，一种准椭圆形的表面破坏的集合，已被建议在相对较小的水体（直径约10 km）上方形成，该水体置于冰壳中，深度小于表面1 km。在这里，我们使用数值模型来量化欧罗巴冰壳中小水体的寿命，并探索它们的化学演化，以了解浅水随时间如何影响冰壳的组成和区域地表地质。我们发现，小金毛虫在地质上比先前描述的更具瞬态性，并且如果储层中含有盐，那么在凝固过程中可能会沉淀出多达几米厚的盐层。