Thermodynamic calculations provide valuable insights into the reactions that drive the profound fluid transformations during serpentinization, where surface fluids are transformed into some of the most reduced and alkaline fluids on Earth. However, environmental observations usually deviate from thermodynamic predictions, especially those occurring at low temperatures where equilibrium is slowly reached. In this work, we analyzed 138 low‐temperature (<40°C) fluids from the Samail ophiolite in Oman to test thermodynamic predictions with environmental observations. Four fluid types were identified through this work. (i) Type 1 circumneutral (pH 7–9) fluids result from fluid interactions with serpentinized rocks common in the shallow subsurface. (ii) Fluids with pH ranging from 9 to 11 and low Si concentrations are products of intermediate stages of serpentinization. (iii) Type 2 hyperalkaline (pH > 11) fluids approach equilibrium with diopside, and with serpentine and brucite actively forming during advanced stages of serpentinization. Lastly, (iv) most fluids sampled in this work deviate from predicted equilibrium compositions and depict various degrees of mixing between Type 1 and 2 fluids. Mixed fluids fall within the same pH range but have considerably higher dissolved Si than intermediate‐type fluids. Hyperalkaline fluids exhibit variable degrees of mixing despite maintaining pH > 11, implying strong buffering capacity of serpentinization‐generated fluids. Overall, this work demonstrates that predicted and measured compositions of serpentinization‐derived fluids can be reconciled using a combination of equilibrium and fluid‐transport simulations. This work substantiates these calculations as useful tools in exploring serpentinization reactions in continents and perhaps in other low‐temperature environments on Earth and beyond.

中文翻译：

---

蛇纹石化液的理论预测与环境观察：来自阿曼萨迈尔蛇绿岩的经验教训

热力学计算为驱动蛇形化过程中的深刻流体转变的反应提供了宝贵的见解，在这些反应中，地表流体被转化为地球上还原性最强的碱性流体。但是，环境观测通常会偏离热力学预测，尤其是那些在缓慢达到平衡的低温环境下进行的观测。在这项工作中，我们分析了来自阿曼Samail蛇绿岩的138种低温（<40°C）流体，以利用环境观测值测试热力学预测。通过这项工作，确定了四种流体类型。（i）1型中性（pH 7–9）流体是由于与浅层地下常见的蛇纹岩的流体相互作用而产生的。（ii）pH值在9到11之间且Si浓度低的流体是蛇纹石化中间阶段的产物。（iii）2型高碱性（pH> 11）液体与透辉石达到平衡，在蛇纹石化的晚期阶段会活跃地形成蛇纹石和水镁石。最后，（iv）在这项工作中取样的大多数流体都偏离了预测的平衡组成，并描绘了1型和2型流体之间的各种混合程度。混合液处于相同的pH范围内，但溶解的硅比中型液体高得多。尽管保持pH> 11，高碱性液体仍显示出不同的混合度，这意味着蛇纹石化生成的液体具有很强的缓冲能力。全面的，这项工作表明，结合平衡和流体传输模拟，可以预测和测量蛇纹石化衍生流体的成分。这项工作证实了这些计算是探索大陆和其他地球及其他地区低温环境中蛇毒化反应的有用工具。