Evolution of the Hida metamorphic rocks from the view point of clinopyroxene mineralogy

从斜辉石矿物学的角度探讨了希达变质带的演化。主要结论如下：Hida变质带斜辉长片麻岩是由变质岩与灰岩的机械混合作用形成的，发生了tr+cc+qz=di+H2O+CO2的反应。inishi型岩石既包括岩石的机械混合产物，也包括角闪岩的脱水熔融产物。岩石的机械混合是交代反应的一个主要过程。这一过程导致体系的组成发生变化，由于简单岩石混合物的自由能与产物的自由能之间的差异而发生变质反应。这类变质反应属于非等化学反应，与一般认为变质反应是在等化学系统内随着温度和压力的变化而发生的观点相反。非等化学反应的概念延伸到流体轴承系统。发现岩石的机械混合变质反应导致流体相的突然释放和组成变化，从而可能发生不同的反应。大陆前缘（即大陆活动带）的吸积作用增强了导致非等化学变质反应的岩石机械混合作用。由于非等化学反应是不可逆的过程，大陆活动带的岩石学性质在威尔逊旋回后继续逐渐改变。

Evolution of the Hida metamorphic belt was discussed from the view point of clinopyroxene mineralogy. Followings are major conclusions.1. Clinopyroxene gneiss of the Hida metamorphic belt was formed by mechanical mixing of metabasite and limestone, thereby the reaction tr+cc+qz=di+H2O+CO2 takes place. Inishi-type rocks include both the product of the mechanical mixing of the rocks and that of dyhydration melting of amphibolite.2. Mechanical mixing of rocks is a major process of metasomatic reaction. This process results in the compositional change of system, and therefore metamorphic reactions due to the difference between the free energy of simple mixture of rocks and that of products take place. This type of metamorphic reactions is of non-isochemical reaction, being in contrast to a general view that metamorphic reactions take place in response to the change of temperature and pressure within isochemical system.3. The concept of non-isochemical reaction extends to fluid bearing systems. We found that the metamorphic reactions by mechanical mixing of rocks results in the abrupt release and compositional change of fluid phases, and consequetly different reactions may occur.4. Mechanical mixing of rocks leading to the non-isochemical metamorphic reactions is enhanced by accretionary process at the leading edge of continents, in other words, continental mobile belts. Since non-isochemical reactions are of irreversible processes, the petrological properties of continental mobile belts continue to be progressively chanced upon Wilson cycle.