Limestone Sedimentology of The Lengkong Formation at Neglasari District, Sukabumi-West Java, Based on Outcrop and Petrography

Abstract

Research about Oligo-Miocene limestones in Java has always been interesting to study in order to understand the relationship between tectonic-volcanic, sedimentation, and petroleum potential. The Lengkong limestone formation is interesting to study especially its sedimentology aspects. There is no Scientific Publication about the Lengkong Formation which discusses detailed sedimentology aspects. Those aspects are important to modify the geological map, scale of 1: 50000 which was published by the ministry of energy and mineral resources. This research was conducted to determine the sedimentology process and development of a depositional environment of the Lengkong formation in the Cimapag River. The research area is located in Neglasari, Lengkong District, Sukabumi. The method used includes field surveys and laboratory analysis. A field survey embodies sedimentology data collection and rock sampling, which was then made into a detailed stratigraphic column. Rock samples were analyzed petrographically for 12 samples to determine microfacies. The results cover three limestone facies, namely wackestone, wackestone-packstone, and packstone facies. The sedimentation of the Lengkong Formation indicates a sea-level decrease of the Interbuild Basin Floor to Deep Marine Off reef