Experimental and Theoretical Studies of Deep Fluids

EAR-9909583流体的释放和运动在许多高压地质过程中非常重要。例如，水溶液是在地壳深部变质过程中产生的，它们的迁移在地壳中重新分配了地质上重要的元素。同样，在地幔中，不同类型岩浆的源区显示出含水流体通过的迹象。随着压力的增加，大多数矿物在富水溶液中的溶解度增加，导致大量物质的运输。然而，尽管有大量证据表明这些过程发生在地球上，但系统的研究仍然有限，因为高压下溶解在流体中的溶质的性质鲜为人知。这个项目涉及高压(5kb)下水溶液及其溶解成分的化学实验和理论研究。该方法是利用深部流体中含水物种热力学性质预测的最新进展来计算在不同环境中存在流体时的模型相关系。这些预测随后被用来指导对主要造岩矿物的溶解度的实验研究。此外，我们正在测定选定的微量元素氧化物的溶解度，以确定在高压流体流动过程中应容易重新分配的元素。最后，我们正在通过测量矿物在含有这些组分的水溶液中的溶解度来研究氯和二氧化碳对深部环境中流体运输的影响。完成后，理论和实验相结合的研究将为研究深部地质环境中流体流动的物理和化学方面提供一个量化框架。

EAR-9909583ManningThe liberation and movement of aqueous fluids is important in many high-pressure geologic processes. For example, aqueous solutions are produced during deep-crustal metamorphism, and their migration redistributes geologically important elements in the crust. Similarly, in the mantle, the source regions for diverse magma types show signs of the passage of water-bearing fluids. The transport of substantial quantities of matter arises from the increasing solubilities of most minerals in water-rich solutions with increasing pressure. However, despite abundant evidence that these processes occur in the Earth, systematic study remains limited because the properties of the solutes dissolved in the fluid are poorly known at high pressure.This project involves experimental and theoretical investigations of the chemistry of aqueous fluids and their dissolved constituents at high pressures (5 kb). The approach is to use recent advances in prediction of the thermodynamic properties of aqueous species in deep fluids to compute model phase relations in the presence of fluid in different environments. The predictions are then used to guide experimental studies on solubilities of major rock-forming minerals. In addition, we are determining solubilities of selected trace-element oxides to identify elements that should readily be redistributed during high-pressure fluid flow. Finally, we are studying the effect of Cl and CO2 on fluid transport in deep environments by measuring mineral solubility in aqueous solutions containing these components. When completed, the combined theoretical and experimental studies will provide a quantitative framework for studying the physical and chemical aspects of fluid flow in deep geologic environments.