佐渡・鶴子鉱床群形成の場の仮想基盤変位法による解析

抄録

Geology and fracture systems in the areas of Sado, Tsurushi and Ohtaki vein type gold deposits, Niigata Prefecture, were re-investigated and studied in detail. Based on the geologic information, some faults younger than vein fractures were dislocated to pre-fault situation on a cross section transversing the Sado deposit. As the result, a flexure became evident at the place where the Sado ore veins exist on the crose section.
On the other hand, simulation analysis was executed to construct a geologic structure model which formed the Sado, Tsurushi and Ohtaki ore veins. The simulation was carried out with Virtual Basement Displacement method which utilize three dimentional elasto-plastic finite element method.
Fracture systems which coincide with the ore veins were formed in the beds above steeply inclined basement in the experiment. The Sado ore vein systems, are best explained by the subsidence of experimental basement at northern part of east-trending line. As for the experimental basement below the Tsurushi ore vein system, northern part of west-northwest-trending line subsided, and as for the Ohtake ore vein systems, southern part of northwest-trending line subsided. These directions on the experimental basement appear to reflect the principal structure of the basement in this area.