1978 Volume 28 Issue 149 Pages 177-190
The Yatani deposits are epithermal vein type deposits situated in acidic tuff member of Yatani formation of Miocene age. The recent study of geology and ore deposits in the mine revealed following facts and suggestions on exploration in the future.
1. The post-ore movement of faults is controlled by simple rule, namely, left lateral movement for NW-SE trending faults and right lateral movement for NE-SW trending ones, which are interpreted as the movement of conjugate set of faults.
2. Shear and tension fractures of veins were formed under E-W trending compressional force, with maximum stress axis pitching 40° to the west in the northern part of No.2 Fault and horizontal in the southern part of No.2 Fault.
3. Veins show remarkable vertical monoascendent zoning of Pb and Zn mostly in the vertical direction with Pb zone in higher level and Zn zone in lower level. Horizontal and vertical zoning is also suggested to exist between Pb-Zn and Au-Ag zones.
4. Zoning pattern and distribution of high grade portion of vein are fully controlled by No.2 Fault and No.3 Fault which played important roles as principal channel ways of ascending ore solution.
