抄録
The Akenobe deposit has been cited as one of the best-known examples of the xenothermal tin-bearing polymetallic vein-type mineralization. It occurs in a formation of slate, basic tuff and basic lava of middle to late Permian Maizuru group as well as Yakuno basic complexes. Detailed examination on the distribution of metals in each vein and the entire mineralization field revealed that the mineralization is roughly divided into three groups; Cu-Zn type, Cu-Sn type and Cu-Zn-Sn type and that a positive correlation exists between zonal arrangement of ores and type of mineralization. In general, Cu-Sn type is dominant in the central portion of the mining field, mainly along NE-SW trending major faults. On the other hand, Cu-Zn type is distributed in the outer zone, especially in the northwestern and southeastern areas.
The Chiemon vein swarm and Ginsei vein both belong to Cu-Zn-Sn type, although they are quite different each other in their metal zoning patterns. The former is composed of Cu-Zn and Cu-Sn type mineralizations which occurred with a considerable tectonic gap, while the latter seems to have been a product of more or less continuous ascending of ore solutions with copper, zinc and tin.
Taking into consideration the mineral zoning patterns and results of stress field analysis, it is concluded that the Chiemon vein swarm has been formed under NW-SE trending compressional stress and the No. 3 fault has served as channelways for ascending ore solutions. Recent exploration works based on these conclusions seem to be quite successful.
