Publications

The new tectonic framework of the Central and East Java areas prior to the recognition of East Java Microplate and re-evaluation of regional geophysical data has revealed the nature of several sub basins, connecting Bogor Trough to Muria Trough and Kendal-Kebumen sub-basins to the south. The Central Java area considered to be high risk for hydrocarbon exploration, despite numerous oil seeps and abundant surface/sub-surface geological data. The main risk lies in the complexities of reservoir rocks, which comprises deep-water Middle Miocene-Pleistocene turbidite complex of Halang and Rambatan Formations. Reconstructing the evolution and development stages of the turbidite fans in specific turbidite system is critical to generate depositional model to reveal new exploration targets. Well exposed Mid-Miocene Cinambo and Rambatan Formations outcrop belt along Baribis and Bumiayu fault system, have been described on detailed stratigraphic sections. Cinambo, Cilutung, Rambatan River and adjacent sections are correlated based on biostratigraphy and traceable marker beds. Composite geologic and paleogeographic maps are constructed to provide site-specific interpretations by combining bed thickness, sand ratio, channel geometry and orientation, and rock packages hierarchy. The Cinambo - Rambatan turbidite system developed in retrograding sequence, comprising 10 “4th-order fan cycles, influenced by short distance non-efficient basinal transport, small sediment input, multiple canyon-fed systems. Sand-prone lithofacies distribution is related to fan development phases, Initiation phase marked by sandy slumped (1) Thick bedded structureless sandstone with great lateral continuity. Growth phase dominated by discontinuous (2) Sandstone conglomerate and (3) Thin-bedded amalgamated sandstone, marking the development of multistory braided channels. Retreat phase showing unconfined layered sheets (4) Ripple crosslaminated sandstone and (5) Sandstone of partial/complete Bouma sequence with great lateral continuity. Sandstones commonly composed of mixed carbonates mud and fine-grained quartz clasts, derived from reworked shallow-marine sediments previously stored in adjacent Jatibarang Low. Intraparticle dissolution due to burial, enhanced porosity values from 5-20%.