Publications

East Java lies on the South East (SE) margin of Sundaland and is filled by thick sequence of Tertiary volcanic sediment. Products of Oligo-Miocene volcanic and quartz deposits are widespread, acting as important hydrocarbon accumulation. SE Java is one location where quartz-rich sandstone is found around volcanic arc. This paper is analyzing Miocene volcanic quartz sandstone that has been discussed as potential reservoir. Sandy facies within Jaten Formation is characterized by flaser sandstone (Sfl), low angle cross lamination sandstone (Sla), wavy lamination sandstone (Sw), ripple cross lamination sandstone (Sr) and horizontal laminated sandstone (Sh) with total thickness of 2 to 9 m. Thin coal layers occasionally present in muddy facies, considered as a good intra formations source rock. Previous studies describes sandstones of the formation contains abundant bipyramidal, faceted crystal, and embayed volcanic quartz grain, indicating volcanic origin. Integrated biostratigraphy, petrography and lithofacies analysis have shown that sandstone of Jaten Formation was deposited in terrestrial to transition environment with fluvial point bar and sand flat facies associations. They are interpreted as a part of lower flank of the volcanoes in the south connected to open marine in the northern part, indicating fluvial to estuary depositional system in active volcanic setting. The existence of thick volcanic materials in SE Java was neglected previously. As a matter of fact, it has valuable implication for basin history, provenance, and reservoir properties that will resolve future exploration problems in SE Java.