インド・オーストラリアプレートの第三紀運動史と西インドネシアの第三系層序について

Abstract

The Tertiary movements of the Indo-Australian plate are re-evaluated, based on the magnetic anomaly zones on the south off the Australian continent. The re-evaluated history of the plate's movements shows a good consistency with the Tertiary tectono-stratigraphic records of tectonic and sedimentary events in petroliferous West Indonesia.The magnetic anomaly zones studied are distributed in the area between the George V Fracture Zone and the Australia-Antarctica Magnetic Discordance Zone. The magnetic anomalies are symmetrically developed with respect to the Southeast Indian Oceanic Ridge in the area. They preserve laterally and chronologically high continuity. The re-evaluation indicates more detailed historical changes in the northward movement of the Indo-Australian plate during the Tertiary than the previous works.This study shows two geohistorical phases in the Indo-Australian plate movements: (I) a slow northward movement of the Australian plate till the latest Eocene, and a sudden acceleration of the movement around the earliest Oligocene, (II) the Late Oligocene acceleration and a plateau of high movement rate till the late Early Miocene, and the early Middle Miocene remarkable acceleration. These events in the plate movements were well recorded in the mega-sequence of the Indonesian Tertiary and Quaternary systems as well as stratigraphic controls of the eustatic sea level fluctuations.The tectono-stratigraphic history in the West Indonesia established an excellent petroleum systems that have been evaluated to yield ca. 46.5 billion barrels of oil equivalent of recoverable hydrocarbons in total.