Abstract
Nanggulan Formation included in the eastern part of South Serayu Basin. This formation locally outcrop in the eastern part of Menoreh Mountain, precisely in Degan and surrounding area. Nanggulan Formation is Eocene rocks which are consist of quartz sandstone, marl and lignite intercalation. Generally Nanggulan Formation is well outcrop along Watupuru and Songgo Rivers. Along these section was also found structural geology; joint, fault and fold which cross cut Nanggulan Formation. The purposes of this research is to record and analyze structural geology and litology data’s of Nanggulan Formation along the Watupuru and Songgo Rivers. The aims of this research is to find out structural condition of the study area and the implication with the distribution on quartz sandstone.
Quartz sandstone generally act as potential reservoir that capable to store fluid. Quartz sandstone cropped out locally in some location with narrow and segmented by structural geology. Degan 2 strike slip fault as synthetic fault formed following the old Meratus structure in Oligo-Miocene. The antithetic fault of Watupuru River 1 in the Plio-Pleistocene has been reactivated to be normal fault. Songgo normal fault is formed coincident with Watupuru fault reactivated. Both Watupuru and Songgo fault configures the small graben. This graben restricting between fine and granule quartz sandstone and also marl.