Publications

Cibulakan Formation as one of the prolific hydrocarbon-bearing intervals has become an interesting study object for many researchers. The continuous outcrop of the Cibulakan Formation in the Cipamingkis River comprises claystone, sandstone, and subordinate limestone of grainstone, packstone, and wackestone facies. The outcrop should be able to give a clearer vertical and spatial variation of sandstone and limestone geometry compared to the conventional core alone. Field observations followed by measuring the section is conducted to distinguish lithofacies and to create a stratigraphic profile from the chosen interval. Samples and thin sections from sandstone and limestone lithofacies are observed further to determine fragment type variation, matrix, cement, texture, and porosity types qualitatively. Fourteen (14) lithofacies have been recognized from the observation, i.e., Slumped Sandstone (A1), Claystone (A2), Slightly-bioturbated Sandstone (B1), Cross-laminated Sandstone (B2), Parallel-laminated Siltstone (B3), Calcareous Claystone (B4), Moderately-bioturbated Sandstone (C1), Hummocky Cross-stratified Sandstone (C2), Skeletal – Coral clast Wackestone (C3), Skeletal-clast Packstone (C4), Coralline Foraminiferal Boundstone (C5), Low-angle Planar Cross-bedded Sandstone (D1), Intensely-bioturbated Sandstone (D2), and Trough Cross-bedded Sandstone (D3). There are four architectural facies in the research interval and each of them is composed of different and specific lithofacies. An ideal parasequence is composed of all Architectural Facies namely : (A) Offshore-Transition (B) Lower Shoreface (C) Upper Shoreface with the whole thickness range between 15 to 25 m and the parasequence shows thickening upward succession. The detailed information about the lithofacies and architectural facies hopefully will provide a better understanding of the facies modelling of the mixed carbonate-siliciclastic depositional setting, new insights for parasequence recognition in clastic shoreline depositional environment and become a reference for other areas lacking in core data and/or outcrop analogue.