Publications

Exploration in Offshore South Java encounters challenging phase since previous efforts have not shown considerable results. For constructing integrated framework, comparison to onshore geology should be undergone. In terms of basin structures, the Offshore South Java displays rift structures with its tectonic position as fore-arc. The basin structures trend in NE-SW with several bands to ENE-WSW. Considering the onshore geology, Wonosari High partitions the graben system and continues to the offshore area. For comparison, basin highs developing in the onshore South Java are Jampang, Karangbolong, Kulon Progo, Munjungan, and Banjarsari Highs. Meanwhile, basin lows are represented as Jogjakarta, Baturetno, Punung, and Watulimo-Ledoyo Lows. Strong repetition on NE-SW lineaments on the onshore geology supports such pattern in the offshore area. That is because extensional regime due to subduction roll-back mechanism spread through East Java in Eocene. This study aims to correlate the onshore to offshore geology in South Java, as well as constructing subsidence mechanism. In order to achieve the goal, this study employs regional seismic interpretations of published works, structural modeling for graben restoration, and surface data. By considering the basin evolution and present-day setting, Offshore South Java has undergone extensional tectonics in its early history and flexural subsidence in recent setting. Extensional structures underneath Offshore South Java prove that such regime developing across East Java in Eocene. Basin depocentre strethches in transition of West and Central Java (south of Nusa Kambangan). Flexural subsidence operates due to thrust wedge mechanism in the southern portion of the basin, in spite of its narrow, linear distribution. Episodic flexural subsidence is observed from unconformities between foredeep sequences. Such phenomenon may occur due to rough surfaces of the subducting slab and trigger intermittent compression.