Geology and Geological Structure in the Hokuroku District, Akita Prefecture
1971 Volume 21 Issue 105 Pages 1-21
Details
1971 Volume 21 Issue 105 Pages 1-21
The Hokuroku district, approximately 40km in W-E length and 20km in N-S, lies within the green-tuff region of the northeastern Japan, where several large "kuroko" deposits, such as Hanaoka, Shakanai, Kosaka and others, are located.
Miocene formations characterized by pyroclastic rocks and violent volcanic activities in the Nishi kurosawa and Onnagawa stage deposited thickly in the central part of the district and thinly in the marginal part.
Detailed geological survey and prospecting by drillings have been carried out for a long time at the Ha-naoka and Kosaka mines, especialy the Miocene volcanism and the stratigraphy of mudstone layers correlated by foraminiferas are investigated by systematic and accurate prospecting methods.
Details of geological structure, stratigraphy and volcanism are given in three areas of Hana-oka, Shinsawa-Shigenai and Kosaka.
