Experimental Determination of Phase Equilibria and Thermodynamic Properties of the System H2O-CO2-NaCl

地壳中的含水流体几乎参与了所有的地质过程，包括部分熔融、热和溶质输运、东道国岩石的反应和蚀变、裂缝中不溶性矿物的沉积以及岩石变形。流体参与这些过程的程度取决于它的化学性质和运输性质。H2O-CO2-NaCl体系非常接近真实的地壳流体。了解该体系的p-V-T-x性质是至关重要的，并且为了能够理解地壳地质过程中的流体-岩石相互作用，显然需要在高温高压下实验确定热物理性质。我们与J. Blencoe合作，提出在压力100 ~ 300 MPa，温度500 ~ 800℃的条件下，通过实验确定H2O-CO2- nacl体系的相关系和热力学性质。这些条件位于H2O-CO2二元临界曲线之上，跨越H2O-NaCl二元临界曲线，适用于许多地壳流体-岩石过程。我们将使用配备氢气服务的内部加热压力容器来确定岩盐饱和表面和水在表面的活性。利用这些数据，我们将能够确定三元体系的相平衡和活度-组成关系。这些结果将对使用合成流体包裹体的系统的研究起到补充作用，并将为在适合地壳地热、变质和变形系统的条件下构建H2O-CO2-NaCl系统的热力学数学模型提供必要的基本输入。

Anovitz and LabotkaEAR-0106990Aqueous fluids in the Earth's crust participate in nearly all geologic processes, including partial melting, heat and solute transport, reaction and alteration of host country rock, deposition of insoluble minerals in fractures, and rock deformation. The extent to which fluid participates in these processes depends on its chemical and transport properties. The H2O-CO2-NaCl system is a close approximation to real crustal fluids. An understanding of the p-V-T-x properties of this system is critical, and an experimental determination of the thermophysical properties at high temperatures and pressures is clearly required to be able to understand the fluid-rock interaction in crustal geologic processes. We, in collaboration with J. Blencoe, propose to determine experimentally the phase relations and thermodynamic properties of the H2O-CO2-NaCl system at pressures ranging from 100 to 300 MPa and temperatures from 500 to 800 degrees C. These conditions lie above the critical curve of the H2O-CO2 binary, span the critical curve in the H2O-NaCl binary, and are appropriate for many crustal fluid-rock processes. We will determine the halite saturation surface and the activities of H2O on the surface with the use of an internally heated pressure vessel equipped with hydrogen service. With these data, we will be able to determine the phase equilibria and the activity-composition relations for the ternary system. The results will be complementary to studies of the system that use synthetic fluid inclusions and will provide the basic input necessary to construct mathematical models of the thermodynamics of the H2O-CO2-NaCl system at conditions appropriate for crustal geothermal, metamorphic, and deformation systems.