Publications

The Barito Basin is located in southeast Kalimantan. It contains a thick Cenozoic sedimentary succession that overlies basement rocks of Paleocene and older age. This paper presents a revised stratigraphy and depositional model for the basin and identifies sediment source areas, based on new lithostratigraphic, biostratigraphic, petrographic and paleocurrent data collected as part of a field-based study.The oldest sedimentary rocks of the Barito Basin succession are assigned to the Tanjung Formation. They include conglomerates, sandstones, siltstones, mudstones, limestones and coal, deposited in a fluvio-tidal coastal plain to marginal marine setting. Palynomorph assemblages indicate deposition began in the late Middle Eocene and foraminifera show that it continued until latest Early Oligocene. During this time, sediment was being sourced from the west and southwest. The Tanjung Formation is overlain by the Montalat Formation in the north and the Berai Formation in the south. These are laterally equivalent in age and were deposited in marginal fluvio-deltaic to fully marine conditions respectively. Foraminiferal assemblages indicate this phase of deposition continued until the Early Miocene. The Warukin Formation overlies these formations, and includes limestones, mudstones, siltstones, sandstones and lignites deposited in a marginal marine to fluviodeltaic setting. Palynomorph assemblages date the top of the formation as Late Miocene. Palaeocurrent data indicate sediment was being transported from the west for the oldest part of the formation, and partly from the east for the younger coal-bearing sequences. It is suggested that this reversal in palaeoflow records uplift of the Meratus Mountains.