Abstract

Middle Neogene (N.5-N.15) deposits within the Rambutan Area of the southwestern part of the South Sumatra Basin comprise a thick, transgressive, fine clastic, sequence overlain by coarser clastic sediments of a regressive sequence.

The early to mid Burdigalian section is composed of shale interbedded with thin very fine sandstone and siltstone which gradually change to shales with marly limestone deposited in upper bathyal to outer neritic environments.

The late Burdigalian sequence is comprised of shale in the lower part gradually changing to interbedded shales and micritic limestones in the upper part representing slope to outer neritic environments.

The Langhian to early Serravalian section consists of repetitive shales and very fine sand beds indicating a gradual change of environments from upper bathyal to inner neritic.

The mid Serravalian to early Tortoinian sequence is composed of shale at the base, changing to interbedded sandstones and shales in the middle, and sandstones, coals and mudstone beds in the upper part of the section, showing environmental variation from prodelta to delta front and delta plain.