Numerical and Experimental Simulation of Reaction-Diffusion Processes in Metamorphic Rocks

从岩石学和岩石成因方面对长崎变质岩中蛇纹岩中的几种复合脉体进行了研究。通过对反应扩散方程的数值模拟，结合矿物溶解度数据，可以估计形成复合矿脉的流体成分。研究了蛇纹岩与泥质片岩之间发育的蛇纹岩混岩内的传质过程，以及由此形成的钠长石。通过比较泥晶片岩和钠长石的体积组成，结合密度数据，可以估计泥晶片岩形成钠长石过程中化学成分的加减量。由于石英和放光石在泥质片岩中的溶解作用，sio2、MgO、CaO和FeO的减少是主要的组成变化。其他组件是固定的。采用单元动力学方法模拟了基于上坡扩散模型的变质层状发育过程。矿物与粒间流体的局部平衡可以增强扩散耦合，引起上坡扩散。这个模型可以很好地解释大多数变质层理。实验研究了钠长石在水热条件下的溶解度。

Several kinds of composite veins in serpentinite from the Nagasaki metamorphic rocks are investigated in terms of petrography and petrogenesis. Numerical simulation of reaction-diffusion equations together with mineral solubility data gives estimation of compositions of the fluid responsible for the formation of the composite veins.Mass transfer within serpentinite melange developing between serpentinite and pelitic schists and the resultant formation of albitite are examined. Comparison of bulk composifin of albitite and that of pelitic schists together with density data enables us to estimate the amounts of addition and subtraction in chemical components during the formation of albitite from pelitic schists. Major change in compositions is subtraction of SiO_2, MgO, CaO and FeO due to dissolution of quartz and actinolite in pelitic schists. Other components are immobile.The process of development of metamorphic layering based on uphill diffusion model is Simulated by Cell Dynamical Method. Local equilibrium between minerals and the intergranular fluid can enhance diffusion - coupling and cause uphill diffusion. Most metamorphic layering can be well explained by this model.Solubility of albite under hydrothermal conditions were experimentally investigated.