Time of Oil Accumulation in Akita Plain Oil Fields, Akita Prefenture

Abstract

In this paper the writer describes a structural history and accumulation of oil in Akita plain which is one of the most important area in Akita sedimentary basin, northeast Japan.The first movement in this plain occured at Yabase structural trend in age of last Funakawa stage, and then a large amount of oil could migrate into the reservoir rocks of Onnagawa formation in the Yabase oil field.In last Tentokuji stage, there were two main anticlines in this plain, one of them at Yabase district and the other at Asahikawa, but the shallow pool at Asahikawa was eroded out, while the pool of Tentokuji formation in Yabase was preserved.