Kinetics of the Smectite-Illite Transformation: An Experimental Study

在温度从25摄氏度到300摄氏度的不同二氧化硅、铝和钾浓度下，将在粘土上进行一系列实验。这项拟议研究的新实验技术已经得到了彻底的测试。它通过含有石英或薄水铝石的两个进料器-炸弹，通过它们在受控温度下的平衡溶解度，提供输入溶液中固定但可调节的二氧化硅和铝浓度。在拟议的实验中，细小的粘土样品将被悬浮在反应器内的流态化床中。然后在每次运行过程中提取固体和溶液的样品，以跟踪反应进程，并将使用各种分析技术来评估流体和固体的组成变化以及伊利石/蒙皂石样品的结构状态。这些实验的结果在几个方面将是重要的。首先，它们将为模拟盆地尺度上的流体流动和成岩作用提供动力学数据。在这样的模型中，水的释放、孔隙度的减少以及与滑石化相关的流体化学和压力的变化是迄今为止高度参数化的重要过程。其次，要解决蒙皂石向伊利石转化的机理。关于滑石化是通过固态还是通过溶解-再沉淀途径进行，一直存在着激烈的争议。在我们的实验中，控制流体组成和流量的能力(因此系统的“封闭性”)使我们能够评估这些因素是否影响反应的速度和能量，以及它们是通过元素反应还是通过多个路径控制表面动力学的质量传输。除了它对伊利尼化动力学的意义外，本文提出的工作还将推广May等人的有价值的平衡溶解度结果。(1986)和Aja等人的。(1991a，b)对K2O-MgO-Al_2O_3-SiO_2-H_2O系各相稳定性的研究。实验结果还应该确定基本粒子的解释是溶液还是多相的混合物(例如，Tardy和Fritz，1981；Aagaard和Helgeson，1983；Nadeau等人，1984；Garrels，1984；以及Altaner，1988)。

A series of experiments will be undertaken on clays under differing silica, aluminum, and potassium concentrations, at temperatures from 25oC up to 300oC. The new experimental technique for the proposed research has been thoroughly tested. It incorporates the dual pumping of solutions through two feeder-bombs containing quartz or boehmite which provide, by their equilibrium solubilities at controlled temperatures, fixed but adjustable silica and aluminum concentrations in the input solutions. In the proposed experiments, the narrowly sized clay samples will be suspended as fluidized bed within the reactor. Samples of both the solid and the solutions will then be extracted during each run to track the reaction progress, and a variety of analytical techniques will be used to evaluate compositional changes in the fluids and solids and the structural state of the illite/smectite sample. The results of these experiments will be important in several respects. First, they will provide kinetic data for modeling fluid-flow and diagenesis on a basin scale. In such models the release of water, reduction in porosity, and change in fluid chemistry and pressure associated with illitization are important processes that have to date been highly parameterized. Secondly, they should resolve the mechanism of the smectite to illite transformation. An active controversy persists as to whether illitization proceeds via a solid-state or a dissolution-reprecipitation path. In our experiments, the ability to control the fluid composition and flow rate (hence "closedness" of the system) allows us to assess whether these factors affect the rates and energetics of the reaction and whether they are dominated by mass transport of surface kinetics through an elemental reaction or through multiple pathways. In addition to its significance to the kinetics of illitization, the work proposed here will extend the valuable equilibrium solubility results of May et al. (1986)and of Aja et al. (1991a, b) on the stabilities of phases in the K2O-MgO-Al2O3-SiO2-H2O system. The experimental results should also resolve whether the fundamental particle explanation is solution or a mixture of multiple phases (e.g., Tardy and Fritz, 1981; Aagaard and Helgeson, 1983; Nadeau et al., 1984; Garrels, 1984; and Altaner, 1988).