Identifikasi Batugamping Kepulauan Sombori, Morowali, Sulawesi Tengah

Abstract

The study area is located in the Sombori Islands, Morowali Regency, Central Sulawesi Province, which regionally belongs to the Salodik Formation of Eocene–Miocene age. This study aims to identify limestone lithology through both macroscopic and microscopic observations, as well as to determine the variation of carbonate rock types composing the Salodik Formation in the study area. The research method applied is petrographic analysis of thin sections to identify rock texture, structure, grain size, sorting, packing, and mineral composition. The results indicate that the lithology of the study area consists of carbonate limestone classified as packstone and grainstone. The packstone is characterized by a non-laminated structure, brown to dark coloration, moderately clastic texture, moderate to poor sorting, open packing fabric, and grain sizes ranging from <0.02 to 1.25 mm. Its composition consists of skeletal grains (foraminiferal fossils), non-skeletal grains (quartz) and opaque minerals, along with a mud matrix composed of carbonate clay and medium- to coarse-grained calcite. The grainstone exhibits a non-laminated structure, brown to reddish coloration, medium- to coarse-grained clastic texture, poor sorting, open packing fabric, and grain sizes ranging from <0.02 to 2.5 mm. Its composition includes foraminiferal fossils, limestone fragments, opaque minerals, and mud. These findings are consistent with the typical lithological characteristics of the Salodik Formation, which formed in a shallow marine environment with moderate to high depositional energy. This study provides an important basis for further diagenetic analysis, depositional environment interpretation, and limestone utilization in the study area.