본 자료는 지난 1979년 일본석유기술협회지(Journal of the Japanese Association of Petroleum Technologists, vol. 44)에 게재된 보고서의 일부로, 신서일본석유개발(주)소속의 Akira Minami가 발표한 논문(일본명 산음-마충 퇴적분지의 분포와 성격)을 한역하였다. 영문이나 우리 말로 바꾸기 어려운 경우가 많아서 확실하지 않은 것은 원전대로 표기하였다.
This article discusses stratigraphy and geological history of continental shelf area covering of offshore San-in to Tsushima islands. Geological data from 5 wells and detailed seismic surveys indicate that sediments in the studied area are divided into 4 stratigraphic groups ranging from Oligocene to Tertiary in age, namely X, H, K, and D groups in ascending order. The oldest X group of Oligocene time comprises paralic sediments including volcanics deposited in the initial stage of basin-formation. N group of mainly lower Miocene time consists of deep marine sediment, representing the highest stage of transgression. Sediments of the K group of middle Miocene time show distinct off-lapping depositional pattern during the basinfilling stage. The youngest D group covers these older groups unconformably. Strong deformation of sediments prior to the deposition of the D group formed many anticlinal structures. Five exploratory wells were drilled at the selected structures, where only minor gas shows were encountered. The area provides the enough palaeotemperature to mature the source rocks at moderate depth.
