1980 Volume 30 Issue 159 Pages 1-18
The Shimokawa ore deposit has been regarded as a cupriferous iron sulphide deposit and is located at an upper horizon of the Shimokawa diabase. The diabase occurs as wall rock and is composed mainly of pillow lavas and diabase sheets with intercalations of slate and sandstone.
The diabase surrounding the ore deposit suffers amphibolic alteration which varys from actinolite to actinolitic hornblende zone towards the orebody. The diabases in the central part of the actinolitic hornblende zone is sheared and changed to chloritized and carbonatized diabase, and simultaneously slate changed to black phyllite. These rocks are successively altered Fe-rich chlorite, quartz and sericite, consequently changed to green schistose rock which always forms disseminated or banded ores. The green schistose rock indicates always metasomatic features and does not occupy any stratigraphic horizon. The evidence suggests that the ore deposit was derived from epigenetic process. result, much new evidence regarding the nature of the mineralization have been gained. Several new orebodies have been discovered in the mining areas as a result of our investigation. In this paper, the wall rock alteration of the Shimokawa ore deposit is reported.
