Geological Structure and Ore Deposits in the Northeastern Area of the Hokuroku Basin, Akita Prefecture, Japan

Abstract

By recent explorations, the new black ore deposits of ginzan under thick volcanic cover of the Quaternary age have been discovered in the northeastern area of the famous Kosaka mining district. The geological occurrences of the ore deposits are very similar to those of the Hanawa ore deposits which are located far southward.
The stratigraphic horizon of the new deposits is also in the upper part of the Nishikurosawa stage roughly corresponding to the Burdigalian, as in the most cases of black ore deposits in the region.
The structural position of the new deposits is near the margin of the Namariyama sub-basin in the west of the elongated Towada basin, in which southern part the Hanawa deposits occur. This subbasin is located close to the northeast of the large circular Hokuroku basin, where along the margin many important black ore deposits have been in operation. The discovery of the new deposits may be a promissing guide to further exploration in this sub-basin.