地质流体岩石反应的地球化学动力学方法

提出了一个以矿物生成和溶解的速率确定体系矿物沉淀的量来模拟水岩反应的新方法。新固相在体系中沉淀的量只依赖于沉淀速率，而不是依赖于水岩之间的平衡。考察了一个矿物溶解生成次生矿物最终趋于平衡的溶解沉淀反应演化，结果表明在水岩体系中对于次生矿物的部分平衡假定在许多情况下都不能成立。在这样的反应演化过程中亚稳矿物与溶液之间总保持过饱和态，矿物的沉淀速率随反应的进展而变化。同时，当主要溶解矿物达到平衡而溶解作用停止时，次生矿物沉淀尚未停止，直到体系饱和指数全部趋于０时，才达到总体平衡。用动力学方法处理地球化学过程中的水岩反应比准稳平衡的简单假设更合理，因为动力学方法更符合自然情况，同时产生了关于时间过程的时间尺度信息。

DYNAMIC APPROACH TO MODELING FLUID ROCK INTERACTION IN GEOCHEMICAL PROCESSES

A new approach to modeling fluid rock interaction is developed, which replaces the assumption of partial equilibrium with a complete calculation of the rates at which minerals form and dissolve. The precipitable amount of a mineral in the systems depends only on its rate of precipitation rather than the assumption of partial equilibrium. The evolution of reaction in close systems towards equilibrium with respect to secondary phases is examined. The results show that the assumption of partial equilibrium with respect to secondary minerals in low temperature water rock systems may not be justified in many instances. The metastable minerals and solution hold almost supersaturate in the evolution of the reaction. The rates of second minerals varied in the evolution of the reaction. When the dissolution of reacting minerals stopped, the precipitation of second minerals still continued, until the all saturation indexes went to 0 and the system was in bulb equilibrium. The model is applied to the weathering of feldspar and quartz with an emphasis on the rates at which minerals form and dissolve. In this paper we suggest that a dynamic approach to treat the process of fluid rock interaction in geochemistry processes may be superior to the simple assumption of metastable equilibrium, because the dynamic approach is more general and yields information on the time scale of the aging process.