SHALLOW MARINE FACIES OF THE MIDDLE MIOCENE KLANDASAN BEDS IN SOUTHERN KUTAI BASIN AND ITS HYDROCARBON SIGNIFICANCE

摘要

The exposure of Klandasan Beds outcrop within Balikpapan Town conveys stratigraphic information toward the subsurface facies distribution in the southern offshore of Kutai Basin. This work describes the examination of depositional facies of Klandsan beds in the southern part of Kutai basin as based on the numerous outcrops sampled in the field. Sedimentological log analysis shows Klandasan Beds composed of thick clean - quartz sandstone with less silt and shale intercalation. The thickness of the beds is up to 183 meters, the and the beds are commonly characterized by cross stratification, i.e. trough and planar cross-bedding, and the occurrence of shallow marine plankton, such as Peneroplis planatus, Reophax scorpiurus, Fluscynielaborneosensis Tan. Based on integration of paleontology, petrology and facies interpretation, the Klandasan Beds demonstrate that the shallow marine facies deposited on the marginal shore to inner shelf environment. The high energy of shallow marine is indicates by the existence of clean quartz sands. Several oil seepages are observed in Klandasan Bed outcrops indicating the occurrence of active petroleum system in the area. We conclude that this study may give better understanding on the shallow marine facies model and deposition, as well as contribute for a new interpretation toward hydrocarbon exploration in the South Kutai Basin.