1983 Volume 33 Issue 180 Pages 201-212
The Furutobe mine, known as one of typical kuroko type deposits, started its production in 1963 after 1.8 million tons of ore reserve was confirmed by more than 100 surface diamond drilling holes.
For the first decade of operation, exploration effort was rewarded by the discovery of additional orebodies in the vicinity of original main orebodies. But when it comes to the second decade, exploration was already limited to small area which was left by a number of drill holes, grid interval of which was only 43 meters and the potentiality looked less promising. However, this detailed exploration both by diamond drilling and tunneling based on new geological concept turned out to be successful by discovering unexpected and small but high grade orebodies.
The followings are the principal geological concepts which will be referred case by case in this report.
1. Reconstruction of fault displacement of post ore nature.
2. Detailed examination of the occurrence of dyke rocks such as dacite and dolerite which intruded the orebody.
3. Examination of detailed succession of ore horizon and tracing of this horizon.
4. Re-examination of white dacite of the footwall.
