Geology and depositional environment of Sambipitu area, Nglanggeran district, Gunung Kidul regency, special province of Yogyakarta, Indonesia

The study area is located in the Nglanggeran district, Gunung Kidul Regency, Special Province of Yogyakarta that was located at the Southern Mountain along the southern part of Jawa Island in Indonesia. This research paper is concern with the objectives of updating the geological map in the scale of l :25,000 and to study the facies association for interpreting the depositional environment of the Sambipitu Formation, which is one of the formations lies in the study area. The methodology that was done throughout the project is by the remote sensing interpretation, fieldworks and laboratory works. Stratigraphically, there are four formations deposited in the study area. There are the Nglanggeran, overlain by the Sambipitu, the Oyo and the Wonosari Formation respectively. All of the formations have distinct characteristics based on lithologies and morphologies. The stratigraphic section was carried out along the Ngalang River to establish the parameters needed for interpreting the depositional environment. The parameters used are facies associations, sedimentary structures and ichnofossils. Based on the dominant sandstones and mudstones, and the sedimentary structures of lenticular bedding, wavy bedding, normal grading, cross beddings, parallel lamination, slumps and convolute bedding, the depositional environment of the Sambipitu Formation is interpreted to be in the shallow marine. The interpretation is supported by the presence of ichnofossils from the Skolithos and Cruziana ichnofacies which can be found within the shallow marine environment.