Abstract
The Hosokura mine is one of the largest lead and zinc mines in Japan. The mine lies in the eastern margin of so called "green tuff region" in northeastern Honshu, and the mine area is composed mainly of propylite, rhyolite, green tuff and tuffaceous sandstone, all of which belong to the Miocene formation. The ore deposit is of the fissure-filling vein type.
Considering the following facts :
(1) the mine location on geological structure in the green tuff region,
(2) the vein pattern,
(3) the direction of arrangements and shapes of igneous bodies,
(4) the gravity anomalies ;
the main structural directions of N-S, E-W NW-SE and NE-SW are presumed in the pre-Miocene basement. The sedimentary environment and the vein systems are also under the influence of the four structural directions mentioned above.
