A method for analyzing low-salinity fluids (up to ~11 wt% NaCl equivalent) that have been equilibrated with felsic melts in high-pressure, high-temperature experiments is reported. Experiments were performed at a pressure of 200 MPa and 800 °C in internally-heated pressure vessels, wherein magmatic fluids were quenched and recovered in a multi-step process for analyses of major (Na, K, Ca, Cl, and F) and trace (Li, Be, Mn, Cu, Zn, Rb, and Sr) elements by ion chromatography and inductively coupled plasma mass spectrometry (ICP-MS). The quenched melts were analyzed for major and trace elements by electron microprobe and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Such analyses permitted the composition of the fluid to be directly measured without the need for mass balance calculations or trapping fluids within fluid inclusions while still enabling the precise determination of partition coefficients. Mass balance calculations tend to overestimate Na, K, Ca, and Be; underestimate Cu, Zn, and F; and are in agreement for Li, Mn, Rb, Sr, and Cl when compared to direct measurements. Additionally, a comparison of partition coefficients calculated from measured and mass balance derived concentrations to available literature data is consistent with mass balance calculations being less accurate than measured values. Thus, direct measurements of quenched fluids by ion chromatography and ICP-MS offer a robust method for characterizing the composition of magmatic-hydrothermal fluids that have been equilibrated with silicate melts.

报告了一种在高压、高温实验中与长英质熔体平衡的低盐度流体（高达 ~11 wt% NaCl 当量）的分析方法。实验在 200 MPa 和 800 °C 的压力下在内部加热的压力容器中进行，其中岩浆流体在多步过程中被淬火和回收，用于分析主要（Na、K、Ca、Cl 和 F）和离子色谱法和电感耦合等离子体质谱法 (ICP-MS) 测定痕量（Li、Be、Mn、Cu、Zn、Rb 和 Sr）元素。通过电子探针和激光烧蚀电感耦合等离子体质谱 (LA-ICP-MS) 分析淬火熔体的主要和微量元素。这种分析允许直接测量流体的成分，而无需进行质量平衡计算或将流体捕获在流体包裹体中，同时仍能精确确定分配系数。质量平衡计算倾向于高估 Na、K、Ca 和 Be；低估 Cu、Zn 和 F；与直接测量相比，与 Li、Mn、Rb、Sr 和 Cl 一致。此外，从测量和质量平衡派生的浓度计算的分配系数与现有文献数据的比较与质量平衡计算的准确性低于测量值一致。因此，