Transgression patterns of Muara Enim Formation at Tanjung Agung Village based on stratigraphic data measurements

Abstract Muara Enim Formation is one of the formations which is composed in the South Sumatra Basin in the Late Miocene Epoch. It has a specific lithology which shows how the conditions of the depositional environment were the formation was deposited. The purpose of this research is to determine the pattern of transgression and regression of Muara Enim Formation. Transgression and regression patterns are used to determine how the shoreline moves. It is caused by the supply of sediment material. The finer sediment material is deposited and the smoother the movement of the material towards the land, showing the indication of transgression, and vice versa. This research uses analytical-interpretative as the method, which is using the result of sampling analysis and then interpreting how the pattern of transgression and regression are changed. This method is used to determine the physical properties of the lithology composing the Muara Enim Formation. Based on field observations on the Air Enim River, it is known that the Muara Enim Formation is composed of lithology dominated by fine grain size (claystone) to medium grain size (tuffaceous sandstone) with thin coal in several locations. Based on field outcrop (surface data) it is known that the claystone lithology is thickened to a younger layer (about 2.5 m thickness) with massive sedimentary structure. It is interpreted that the Muara Enim Formation was deposited in a transgression pattern in a depositional phase which was influenced by sediment supply factors and weak depositional currents.