The strontium isotope ratio (⁸⁷Sr/⁸⁶Sr) is a natural tracer commonly used to determine water sources, water flow trajectories, and mixing relationships. In high-temperature hydrothermal systems, the low solubility of retrograde minerals such as calcite and anhydrite may significantly reduce the dissolved Sr concentration. Further contribution of Sr along the flow path from isotopically distinct sources will alter and potentially mask the original Sr isotopic signature of the fluid, limiting the potential of ⁸⁷Sr/⁸⁶Sr data for reconstructing fluid flow patterns. This study investigates the tracing potential of ⁸⁷Sr/⁸⁶Sr in terms of fluid circulation within the El Chichón volcano hydrothermal system. Although limestone aquifers are evidenced in the region, the ⁸⁷Sr/⁸⁶Sr signature of most thermal fluids from the volcano does not indicate any major Sr contribution from such lithologies, but rather reveals that Sr is inherited from volcanic rocks. An isotope-enabled reactive transport model is performed to investigate under which conditions a connection between the limestone and volcanic aquifers is compatible with chemical and Sr isotopic compositions of the thermal springs. Results indicate that the ⁸⁷Sr/⁸⁶Sr signature of a sedimentary fluid with moderate Sr concentration can be completely modified into a magmatic signature after interacting with Sr-rich primary minerals, such as plagioclases, within short period of times (<1 year). Primary minerals release magmatic Sr to the fluid while secondary minerals (such as calcite) progressively precipitate and remove the initial sedimentary Sr. The El Chichón hydrothermal system hence represents a case where the ⁸⁷Sr/⁸⁶Sr of most springs does not keep any memory of the circulation through the sedimentary basement, as magmatic Sr dominates the isotopic signature. A certain analogy exists with hydrothermal fluids vented at oceanic spreading centers, whose ⁸⁷Sr/⁸⁶Sr signature departs from seawater and reflects Sr inherited from water-basalt interaction.

锶同位素比（⁸⁷ Sr/ ⁸⁶ Sr）是一种天然示踪剂，常用于确定水源、水流轨迹和混合关系。在高温热液系统中，方解石和硬石膏等逆行矿物的低溶解度可能会显着降低溶解的 Sr 浓度。来自不同同位素来源的 Sr 沿流动路径的进一步贡献将改变并可能掩盖流体的原始 Sr 同位素特征，从而限制⁸⁷ Sr/ ⁸⁶ Sr 数据重建流体流动模式的潜力。本研究探讨了⁸⁷ Sr/ ^{86的示踪潜力}Sr 在 El Chichón 火山热液系统内的流体循环方面。尽管该地区存在石灰岩含水层，但来自火山的大多数热流体的⁸⁷ Sr/ ⁸⁶ Sr 特征并未表明此类岩性对 Sr 有任何主要贡献，而是表明 Sr 是从火山岩中继承的。使用同位素激活的反应传输模型来研究在何种条件下石灰岩和火山含水层之间的连接与温泉的化学和 Sr 同位素组成相容。结果表明，⁸⁷ Sr/ ⁸⁶中等 Sr 浓度的沉积流体的 Sr 特征在与斜长石等富含 Sr 的原生矿物相互作用后，可在短时间内（<1 年）完全转变为岩浆特征。原生矿物将岩浆 Sr 释放到流体中，而次生矿物（如方解石）逐渐沉淀并去除初始沉积 Sr。因此，El Chichón 热液系统代表了大多数泉水的⁸⁷ Sr/ ⁸⁶ Sr 不保留任何记忆的情况。通过沉积基底的循环，因为岩浆 Sr 主导同位素特征。与在海洋扩张中心排放的热液存在某种类比，其⁸⁷ Sr/ ⁸⁶Sr 签名从海水中分离出来，反映了从水-玄武岩相互作用中继承的 Sr。