岩手県赤金鉱山における高温交代銅鉄鉱床の鉱化(I)

流体包有物の充填温度と塩濃度

抄録

The filling temperature and the salinity of fluid inclusions in quartz and calcite occurred from the Hozumi and Sakae pyrometasomatic copper and iron deposits of the Akagane Mine were investigated by means of the heating stage and freezing stage microscope. Quartz was collected from two different stages of mineralization. The earlier stage one (Quartz-I) is intimately associated with pyrrhotite and chalcopyrite, and the later stage one (Quartz-II) is mainly accompanied by pyrite. Calcite coexisting with epidote, quartz-II and chlorite is considered to belong to the latest mineralization stage.
The main filling temperature ranges are measured as follows: quartz-I 260_??_320°C, quartz-II 230_??_290°C, calcite 210_??_240°C. This result is concordant with the mineral succession obtained from the field evidence and microscope observation. Generally speaking, the filling temperature in minerals of the Sakae deposit are similar to those of the Hozumi deposit, and is inclined to rise from upper to lower levels at the two deposits, and from peripheral (the 5th ore body) to central ore bodies (the main and 3rd ore bodies) at the Sakae deposit. This fact will suggest the flow direction of ore-forming fluid originated in some deeper places of the granite porphyry masses.
On the other hand, the salinity of fluid inclusions in quartz-I range from 12.5 to 13.3 weight percent for the Hozumi deposit and from 18.6 to 21.4 weight percent NaCl equivalent for the Sakae deposit.