Structure of the Motoyama Kuroko Deposits, Kosaka Mine, Akita Prefecture

Abstract

The Motoyama deposits of the Kosaka Mine, Akita Prefecture, are one of the typical Kuroko deposits in Japan. The deposits which originally had a bedded form, are imbricated by the strike-slip thrusts which took place in close connection with the post-ore intrusion of the Akamori dacite.
The zonal arrangement of the ores in the deposits is considered to have resulted from the lateral transition of the ore during the deposition. Discussions of the period of the mineralization suggest a syngenetic origin for the deposits.