Saturn's ice‐covered moon Enceladus may contain the requisite conditions for life. Its potentially habitable subsurface ocean is vented into space as large cryovolcanic plumes that can be sampled by spacecraft, acting as a window to the ocean below. However, little is known about how Enceladus’ ocean fluids evolve as they freeze. Using cryo‐imaging techniques, we investigated solid phases produced by freezing simulated Enceladean ocean fluids at endmember cooling rates. Our results show that under flash‐freezing conditions (>10 K s⁻¹), Enceladus‐relevant fluids undergo segregation, whereby the precipitation of ice templates the formation of brine vein networks. The high solute concentrations and confined nature of these brine veins means that salt crystallization is kinetically inhibited and glass formation (vitrification) can occur at lower cooling rates than typically required for vitrification of a bulk solution. Crystalline salts also form if flash‐frozen fluids are re‐warmed. The 10 µm‐scale distribution of salt phases produced by this mechanism differs markedly from that of gradually cooled (∼1 K min⁻¹) fluids, showing that they inherit a textural signature of their formation conditions. The mineralogy of cryogenic carbonates can be used as a probe for cooling rate and parent fluid pH. Our findings reveal possible endmember routes for solid phase production from Enceladus’ ocean fluids and mechanisms for generating compositional heterogeneity within ice particles on a sub‐10 µm scale. This has implications for understanding how Enceladus' ocean constituents are incorporated into icy particles and delivered to space.

中文翻译：

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模拟的土卫二海洋流体冻结过程中结晶相和非晶相的分配

土星的冰雪覆盖的月亮土卫二可能包含生命的必要条件。它潜在的可居住的地下海洋作为大型低温火山烟气被排放到太空中，可以通过航天器采样，作为通往下方海洋的窗口。然而，关于土卫二的海洋流体在冻结过程中是如何演化的知之甚少。使用冷冻成像技术，我们研究了以端构件冷却速率冷冻模拟的Enceladean海洋流体所产生的固相。我们的结果表明，在速冻条件下（> 10 K s ^-1），与土卫二相关的流体会发生分离，从而使冰样的沉淀形成盐水静脉网。这些盐水脉的高溶质浓度和有限的性质意味着盐的结晶在动力学上受到抑制，并且玻璃化的形成（玻璃化）可以在比本体溶液玻璃化通常所需的更低的冷却速率下发生。如果重新加热急冻流体，也会形成结晶盐。这种机理产生的盐相的10 µm尺度分布与逐渐冷却（〜1 K min ^-1）流体，表明它们继承了其形成条件的纹理特征。低温碳酸盐的矿物学可以用作冷却速率和母液pH值的探针。我们的发现揭示了从土卫二海洋流体中产生固相的可能的最终成员路线，以及在小于10 µm规模的冰粒内产生成分异质性的机制。这对于理解土卫二的海洋成分如何被整合到冰冷的颗粒中并传递到太空中具有重要意义。