On the Formation Temperatures of Minerals by the Heating Microscope Stage Method(I)

Abstract

In order to determine the range of formation temperatures of ore deposits, the liquid inclusions occurring in minerals from the following four mines in Japan were studied by the heating microscope method. In this experiment, the filling temperatures were determined by observing the disappearance of gas bubbles in the liquid inclusions.
Minerals whose filling temperatures were determined are quartz and calcite. The specimens of quartz were collected from three mines, Seigoshi, Amagi and Akatani, and those of calcite from the Nakatenjo mine, a branch mine of the Nakadatsu mine. They are closely associated with the ore minerals in each deposit.
Judging from the modes of occurrence of the host minerals, most liquid inclusions occurring in these specimens seem to be of primary origin.
Temperature data obtained in this study are shown in Table 1 and Figs. 3-4.
Ore deposits of both the Seigoshi and Amagi mines consist of gold quartz veins and are said to be of typically epithermal origin. Large parts of the hematite deposits of the Akatani mine are of the replacement type in Paleozoic limestone and are considered to be of hydrothermal origin. Lead and zinc deposits of the Nakatenjo mine may also belong to hydrothermal deposits of a low temperature type.
Therefore, the temperature data obtained in this study agree well with the formation temperatures which have been estimated, though qualitatively for these deposits, from other geological phenomena. The data give quantitative evidence to the former qualitative estimate.