Sirait (1986) is in the opinion that the deposition of the volcanic has been primarily due to fluvial and sub-aqueous processes in which layering (strata) formation is expected. Elf (1992) has declaring that a sedimentary source from the south is prominent for some of the volcanic. Some hydrothermal alteration as well as sub-aerial weathering is also evident, which is interpreted to be occurred during early deposition of the volcanics.

Elf (1992) is in the opinion that the Jatibarang volcanic is of Eocene to Oligocene age and was deposited following initiation of back arc basin as a result of the Late Cretaceous up to Early Tertiary subduction zone running approximately North East – South West extending from the Meratus zone in East Kalimantan and curving due West to the south of present day of Jatibarang field location (Hamilton, 1979). The volcanic section thickness may attain as thick as 1,200 meters and directly unconformable overlying the metamorphic or igneous pre-Tertiary basement (Soulisa, 1979 in Elf, 1992), yet no wells ever drilled to penetrate the entire volcanic section. Kalan, et.al (1994) concluded that tuffaceous volcanics are the best producing reservoir in the Jatibarang Field, and that productive tuffs can be distinguished on logs. From their results shows that log correlations have isolated two producing tuff layers in the field. The two layers are separated in most field area by a generally non­productive basaltic/andesitic lava layer. Two main log types were defined representing felsic tuff and basaltic/andesitic.