Fluid inclusion study on the contact metamorphic tungsten ore deposits of the Yaguki mine
1982 Volume 32 Issue 172 Pages 107-116
Details
1982 Volume 32 Issue 172 Pages 107-116
The filling temperature and the salinity of fluid inclusions in minerals from the pyrometasomatic copper-iron and tungsten ore deposits of the Yaguki mine were measured by means of a microscope with heating and freezing stages. The present works aim at the clarification of mineralization relationships between the two kinds of deposits. The results could be summarized as follows:
(1) The ranges of filling temperature of fluid inclusions in quartz, scheelite and epidote from the tungsten deposits are 200°-340°(265°), 220°-330°C(270°C), and 230°-330°C(290°C), respectively (parentheses indicate arithmetical mean values). And the ranges of the salinity of the former two minerals mentioned above are 1.0-2.9 and 2.9-10.5% in NaCl equivalent concentration, respectively.
(2) The range of the filling temperature of fluid inclusions in quartz and calcite from copper-iron deposits is 200°-360°C(291°C), which is almost the same as that of the Akagane mine, Iwate Prefecture. The salinity could not be measured because of a minute inclusion size.
(3) The results of the fluid inclusion study indicate that the mineralization stage of tungsten is later than that of copper-iron. This process of mineralization is supported by the mineral succession and mineral assemblages obtained from the field evidence and the microscopic observation.
(4) The filling temperatures of inclusions from copper-iron ore deposits decreases distinctly toward the upper level, whereas those of inclusions from tungsten ore deposits are confined to a narrow range in spite of the depth.
(5) There is a linear relationship between the filling temperature and the salinity of fluid inclusions in quartz from the tungsten deposits, while scheelite occupies a very narrow area in the diagram of filling temperature vs. salinity of inclusions. From these facts, it is inferred that scheelite crystallized under the condition of narrow ranges of both temperature and salinity.
