This work presents the first chemical and isotopic (δ 13 C-CO 2 , δ 13 C-CH 4 , 3 He, 4 He, 20 Ne, 40 Ar, 36 Ar, δ 18 O, and δD) data for fluid discharges from Guallatiri volcano, a remote and massive stratovolcano, which is considered as the second most active volcano of the Central Volcanic Zone (CVZ) in northern Chile. Fumarolic gases had outlet temperatures of between 80.2 and 265 °C, and showed a significant magmatic fluid contribution marked by the occurrence of SO 2 , HCl, and HF that are partially scrubbed by a hydrothermal aquifer. The helium isotope ratios (< 3.2) were relatively low compared to those of other active volcanoes in CVZ, possibly due to contamination of the magmatic source by 4 He-rich crust and/or crustal fluid addition to the hydrothermal reservoir. Geothermometry in the H 2 O-CO 2 -CO-H 2 -CH 4 system suggests equilibrium temperatures of up to 320 °C attained in a vapor phase at redox conditions intermediate between those typical of hydrothermal and magmatic environments. Thermal springs located 12 km northwest of the volcano’s summit had outlet temperatures of up to 50.1 °C, neutral to slightly basic pH, and a sodium bicarbonate composition, typical of distal fluid discharges in volcanic systems. Cold springs at the base of the volcanic edifice, showing a calcium sulfate composition, were likely produced by interaction of shallow meteoric water with CO 2 - and H 2 S-rich gases. A geochemical conceptual model was constructed to graphically represent these results, which can be used as an indication for future geochemical monitoring and volcanic hazard assessment.

中文翻译：

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智利北部瓜拉蒂里火山岩浆-热液系统气体和水排放的地球化学

这项工作提供了第一个化学和同位素（δ 13 C-CO 2 、δ 13 C-CH 4 、3 He、4 He、20 Ne、40 Ar、36 Ar、δ 18 O 和 δD）数据。 Guallatiri 火山，一座偏远的大型成层火山，被认为是智利北部中央火山区 (CVZ) 中第二活跃的火山。延胡索气的出口温度在 80.2 到 265 °C 之间，并显示出显着的岩浆流体贡献，其特征是 SO 2 、HCl 和 HF 的出现，这些气体被热液含水层部分洗涤。与 CVZ 中其他活火山相比，氦同位素比 (< 3.2) 相对较低，可能是由于 4 富 He 地壳和/或地壳流体添加到热液储层中对岩浆源的污染。H 2 O-CO 2 -CO-H 2 -CH 4 系统中的地温测量表明，在介于典型热液和岩浆环境之间的氧化还原条件下，气相中达到的平衡温度高达 320 °C。位于火山顶峰西北 12 公里处的温泉出口温度高达 50.1 °C，pH 值为中性至微碱性，碳酸氢钠成分是火山系统远端流体排放的典型特征。火山结构底部的冷泉显示出硫酸钙成分，可能是由浅层大气水与富含 CO 2 和 H 2 S 的气体相互作用产生的。构建了地球化学概念模型以图形表示这些结果，可用作未来地球化学监测和火山灾害评估的指示。