Development of a Numerical Model for the PVTX Properties of Na-K-Ca-Fe-C1 Solutions in Magmatic/Hydrothermal Ore Deposits

BodnarEAR-0125918将进行为期三年的实验研究，以确定与浅层花岗岩岩浆有关的岩浆-热液矿床在适宜的温度和压力范围内流体不混溶的温度-压力-成分(PTX)界限。这项研究将集中在含有Na、K、Ca和Fe氯化物的水溶液中的流体组成，从包含Na-K、Na-Ca和Na-Fe氯化物的较不复杂的子系统开始。不相容流体的样品将使用合成流体包裹体技术就地捕获，并将使用标准的微温分析技术确定流体的组成。这些成分数据将被用来开发一个经验的数值模型，以预测参与岩浆-热液作用的P-T条件。该模型将只需要在流体包裹体的常规显微测温和/或微量化学分析过程中容易获得的信息。对水-氯化钠-氯化钾体系的初步研究证明了该项目的可行性。数据证实，合成的流体包裹体捕获了实验运行条件下存在的具有代表性的流体样本(S)，并在淬火过程中保持这些成分到实验室环境条件下。此外，对共存的富液体包裹体和富气相包裹体的常规显微测温分析也可用于确定流体成分。水-氯化钠-氯化钾体系的初步数据表明，钠和钾在共存的液体和蒸汽之间的分配随温度和压力而系统地变化。具体地说，钠在液体中的分配随着温度的升高和压力的降低而变得不那么明显。

BodnarEAR-0125918A three-year experimental study will be conducted to determine the temperature-pressure-composition (PTX) limits of fluid immiscibility over the temperature and pressure range appropriate for magmatic-hydrothermal ore deposits associated with shallow granitic magmas. The study will focus on fluid compositions in aqueous solutions containing Na, K, Ca, and Fe chlorides, starting with the less-complex sub-systems containing Na-K, Na-Ca, and Na-Fe chlorides. Samples of immiscible fluids will be trapped in situ using the synthetic fluid inclusion technique, and compositions of the fluids will be determined using standard microthermometric analytical techniques. The compositional data will be used to develop an empirical numerical model to predict P-T conditions attending magmatic-hydrothermal processes. The model will require only information that is easily obtainable during conventional microthermometric and/or microchemical analysis of fluid inclusions. The feasibility of the project has been documented by preliminary studies on the water-NaCl-KCl system. The data confirm that the synthetic fluid inclusions trap a representative sample of the fluid(s) present at experimental run conditions, and maintain these compositions during quenching to ambient laboratory conditions. Moreover, conventional microthermometric analysis of the coexisting liquid-rich and vapor-rich inclusions can be employed to determine the fluid compositions. Preliminary data for the water-NaCl-KCl system show that partitioning of sodium and potassium between coexisting liquid and vapor varies systematically with both temperature and pressure. Specifically, sodium partitioning into the liquid phase becomes less pronounced with increasing temperature and with decreasing pressure.