Palynostratigraphy and Paleoenvironment of Bukit Tigapuluh Area in the Jambi Subbasin from Oligocene to Miocene

The Oligocene-Miocene trajectory exposed at the Lubuk Lawas and Lubuk Bernai Stratigraphic Tracks in Bukit Tigapuluh, Jambi Subbasin, Indonesia, archives remnants of equatorial vegetation during extreme global warming and near the beginning of the East Java-Eurasia microcontinent collision, and was carried out using mapping surface analysis, petrological analysis, sedimentology, stratigraphy and palinology. The rock units were deposited during one sedimentation phase, that is the continental deposition phase, which consists of conglomerates, gravel sandstones and sandstones that fill the basin followed by transgressive deposits associated with the deepening of the basin environment. Three palynozones Meyeripollis naharkotensis (Oligocene), Florschuetzia trilobata (Early Miocene) and Florschuetzia meridionalis (Middle Miocene) were identified stratigraphically on the basis of these pollen. The rock layers are deposits from the Early Oligocene to Middle Miocene from bottom to top. The depositional environment changed over time, passing from a narrow, steep-sided tectonic basin, during the Early to Late Oligocene, followed by a lacustrine basin to a palustine with oceanic influence, as a result of distensive E-W movement between the Jambi Fault and the Sunda Fault in the Late Oligocene to the Middle Miocene. Occurrence of taxonomically highly diverse angiosperm pollen in all three palynozones attests to an extremely rich inland and nearshore tropical flora under a strong seasonal rainfall regime. The climate remained warm and became increasingly humid towards the end of the Miocene. The nature of the environment is related to the dynamics of the opening of the basin opening.