Geology and Ore Deposits of the Ikuno Mine, with Special Reference to the Gold-Silver Veins

Abstract

The Ikuno mine is located in the Inner Zone of Southwest Japan and is well-known, together with the Akenobe mine, as one of the typical xenothermal deposits. Geology of this area is composed of the Tamba group, early Permian, and the Ikuno group, late Cretaceous to Paleogene, which consists. of various volcanic and pyroclastic rocks from rhyolitic to basaltic. Ore deposits are polymetallic veins in the Ikuno group and its accompanying intrusive rocks, showing the typical zonal arrangement, that. is, the polymetallic zone in the central part and the gold-silver zone in the outer part.
The writers made observation on the recently-developed gold-silver veins (Nishi-rokugo vein of the Tasei vein group, Koei vein of the Kanagase vein group, etc.) with the naked eye and under the microscope, and they were able to clarify characteristics of the veins. From the results of these studies and the geochemical survey carried out for the Aokusa vein group, some possibilities of discovery of new gold-silver veins have been obtained.