The research location is the northern part of the Basin of Limboto Lake; the focus of the research is the limestone outcrop with 24 meter thickness in Yosonegoro area. The purpose of the study is to find out facies, standard microfacies and depositional environment on Limboto limestone. The research method carried out consisted of three methods namely the measured section, petrographic analysis and biostratigraphy analysis.
The limestone facies in the Yosonegoro area consist of two facies. Then, based on sedimentary structure, composition, color, precipitation texture, terrestrial origin components and the organism content, the two facies can divided into three different microfacies. Paleobathymetry shows a deepening from the middle shelf - upper slope to the upper slope - lower slope due to the sea level rise. Compilation of standard microfacies and paleobathymetry types shows changes in depositional environment from the slope environment to the toe of slope environment. The result of this study will be led researchers to propose the name of the new formation, which is the Limboto Limestone Formation according to specific location and characteristics from the previous formation name of the Clastic Limestone Formation.
