Geology and Ore Deposits of the Kamikita Mine, Aomori Prefecture (2)
with Special Reference to the Volcanism and Mineralization in the Okunosawa Formation
1968 Volume 18 Issue 90 Pages 185-199
Details
1968 Volume 18 Issue 90 Pages 185-199
On the basis of geological data obtained from diamond drilling, surface and underground survey, the Miocene acidic volcanism of the Kamikita mine district can be summarized as follows :
1) The acidic volcanic activity was predominant in the Okunosawa Formation and the overlying formation.
2) The Okunosawa Formation is composed of acidic lava flow (so-called lava dome), pyroclastic rocks accompanied by the acidic volcanic activity and sedimentary tuff.
3) The pyroclastic volcanic activity in the Okunosawa Formation is divided into two stages, OB1 and OB2, respectively. The OB1 stage was the initial volcanism which formed pyroclastic rocks and several lava domes. The OB2 stage is the final of which activity was violent and widespread.
4) An explosive eruption took place at the beginning of OB2, during which the black ore deposits of the Kamikita Mine was formed. The other explosion took place during the OB2 volcanism. Thus, the primary ore deposits had been destroyed and the beded deposits were formed.
