蔵王温泉の生成機構に関する一考察

抄録

The geological survey and the observation of microtremors showed that the Zao Hot Springs are situated on complicated sedimentary formation, composed of pyroclastic rocks and mud flows, and accumulated in an ancient volcanic crater. Several fissure zones, running in the direction of N 20°-40° W, have been noted in this area, and they are found to be parallel to the crater wall (see Fig.1). Hot spring vents are distributed mostly within a limited zone lying between the fissure lines F₄ and F₆. These springs are formed by mixing of groundwater and magmatic emanation ascending from the deep magma reservoir through the fissure structure. The discharge of the springs depends on the amount of groundwater supplied. As there is no simple relation between the content of soluble material and the temperature of these spring waters, it is thought that heat is supplied to the spring waters in a different manner for the magmatic components. It may be concluded that the supply of heat depends on the thermal conductibility of rocks.