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 on its petroleum potential. Lengkong formation as a part of those limestones is interesting to study especially about its sedimentology aspects. There is no Scientific Publication about the Lengkong Formation which discuss detailed sedimentology aspects. Those Aspects are important as primary data to make the geological map, scale of 1: 50000 which is published by the ministry of energy and mineral resources. This research was conducted in order to determine the sedimentology process and the development of a depositional environment of Lengkong formation in the Cimapag River. The research area is located in Neglasari,  Lengkong District, Sukabumi. The methods used are field survey and laboratory analysis. A field survey conducted sedimentology data collection and rock sampling which is then made into a detailed stratigraphic column. Rock samples were analyzed by petrographic on 12 samples to determine microfacies. The results showed three limestone facies, namely facies wackestone, wackestone-packstone, and packstone. The sedimentation of Lengkong Formation generally indicated the decrease in the sea level of Interbuild Basin Floor to Deep Marine Offreef.