Publications

The Cisubuh Formation is known as a regional seal and can also serve as a gas reservoir. In the stratigraphic column of the Bogor Basin, the Cisubuh Formation can be correlated with the Subang Formation, Kaliwangu Formation, Cigadung Formation, and Cantayan Formation. The purpose of this research is to determine the content of mollusc fossils in the Kaliwangu Formation. Lithological data and mollusc fossils content were obtained based on rock samples collected during fieldwork in 2023, the investigation results from the Directorate of Geology in 1968, and Dutch investigations from 1927-1935 stored in the Geological Museum. Mollusc fossils from fieldwork in 2023 were described following Leloux and Wesselingh, 2009. Mollusc fossil data were subsequently used to identify the age and deposition environment. The Kaliwangu Formation found in the Leuwimunding area, Majalengka Regency, is composed of lithology consisting of sandstone and intercalated sandstone with mudstone. The Kaliwangu Formation in the research area is interpreted as equivalent to the Cisubuh Formation. The variation of mollusc fossils found in this formation is dominated by species such as Turritella bantamensis, Turritella angulata djadjariensis, Natica vitellus, Natica lineata, Timoclea bataviana, Marginella (Cryptospira) ventricosa sangiranensis, and Bicorbula tjiguhanensis. The collection of 62 mollusc fossil species indicates a depositional environment ranging from intertidal to shallow marine. The Cisubuh Formation in the research area based on the presence of Turritella bantamensis can be characterized as Mollusc Bantamian Stage.