Geology and depositional environment of the Miocene Wonosari in Nglipar Area, Wonosari, Yogyakarta, Indonesia

The study area is situated in Wonosari District, Gunung Kidul regency, Special Province of Yogyakarta. The frequent deposition and sedimentation process causing the interpretation of the depositional environment of the Miocene Wonosari Formation in the Nglipar area to become hard. These problems become one of the factors for not having clear statement of the depositional environment of the Miocene Wonosari Formation in Nglipar area, Wonosari. Thus this paper investigated the depositional environment, sedimentary facies of the Miocene Wonosari Formation in Nglipar area and updating the geological map in scale of 1:25,000. The methodology which was done throughout the research is the field surveying, and laboratory analysis. According to stratigraphy, there are two formations deposited in the study area which is known as Oyo and Wonosari formation respectively. The formations were studied in term of geomorphology and its lithology. Depositional environment of Miocene Wonosari Formation in Nglipar is interpreted by using the stratigraphy section that done at three locations. The parameters such as facies classification, sedimentary structures and fossils were used. Based on the sedimentary structure of cross bedding and the presence of fossil such as Globigerinid sp. and Orbulinids sp., the depositional environment of Miocene Wonosari Formation is shallow marine environment.