Geological setting of the Phu Khanh Basin based on updated geological-geophysical data

Abstract

The Phu Khanh Basin is a Tertiary sedimentary basin located in deep a water area adjacent to the continental shelf of Central Vietnam, which has been begun to form since the Eocene(?)/Oligocene to the Quaternary. This area has previously only been briefly studied based on satellite magnetic, gravity data and some 2D multichannel seismic lines. In this article, the authors present the most recently interpreted and merged gravity data to update the research results on geological structure, tectonics and the history of geological evolution of the Phu Khanh Basin, which are considered significant contributions for hydrocarbon exploration campaigns in the future. Our new results show that mechanism of the the Phu Khanh Basin formation was started by a rifting process with most of it located in the central basin, controlled by four main fault systems, including the NW - NE system, the NE - SW system, sub-meridian system and less active is the sub-latitude system. The evolution of the basin has undergone through four main phases of different tectonic deformation, which are characterized by its typical geodynamic regimes and tectonic activities. These evolutionary phases can be briefly described as follows: (i) Paleocene peneplanation phase, (ii) The active rifting phase in Eocene/Oligocene-Early Miocene, (iii) The Middle Miocene thermal subsidence phase and finally (iv) The Late Miocene-Quaternary shelf building phase. However, the issue of determining the Eocene age at the bottom of the basin has so far remained unclear and elucidated by the lack of deep wells penetrating the deepest region of the basin.