Mineral Dissolution and Precipitation Rates Under Near Equilibrium Conditions: An Application of Isotopic Doping Techniques to the CaO-MgO-SiO2-H2O System

本研究将利用一种新开发的方法来测量CaO-MgO-SiO2-H2O体系中矿物在100-400℃温度和高达1 kbar压力下的接近平衡溶解和沉淀速率。该方法包括测量与亚稳态反应物和稳定产物矿物反应时晶体生长和溶解的速率。所采用的技术包括利用同位素示踪剂在实验期间连续监测反应进程。通过系统地改变“反应物”和“生成物”的相对表面积，可以建立亚稳态条件和相对饱和状态对矿物相的调节。实验结果将提供在大范围温度和压力下地球化学重要矿物的接近平衡速率数据。这些数据可以包含在反应路径代码中，如EQ6，这将允许为活跃热液系统中流体的化学演化构建更好的模型。

9418719 Seyfried This research will utilize a newly developed method to measure near equilibrium dissolution and precipitation rates of minerals in the CaO-MgO-SiO2-H2O system at temperatures from 100-400 oC and pressures up to 1 kbar. The method involves measuring rates of crystal growth and dissolution during reaction of fluids with metastable reactant and stable product minerals. The technique to be used involves monitoring reaction progress continuously during experiments by means of isotopic tracers. Metastable steady state conditions and adjustments of the relative states of saturation with respect to mineral phases can be established by systematically changing the relative surface areas of "reactant" and "product". Results of the experiments will provide near-equilibrium rate data for geochemically important minerals at a wide range of temperatures and pressures. These data can be included in reaction path codes such as EQ6, which will allow construction of better models for the chemical evolution of fluids in active hydrothermal systems.