Karakterisasi Petrografi dan Klasifikasi Litologi Batuan pada Daerah Umpam dan Sekitarnya, Kecamatan Lengkiti, Kabupaten Ogan Komering Ulu, Sumatera Selatan
DOI:
https://doi.org/10.29303/goescienceed.v7i1.1681Keywords:
Benthic Foraminifera, Bathymetry, Baturaja Formation, Gumai Formation, South Sumatra BasinAbstract
The Umpam area and its surroundings, Lengkiti District, Ogan Komering Ulu Regency, South Sumatra, are located within the South Sumatra Basin and exhibit complex lithological variations. This study aimed to characterize rock types petrographically and to establish lithological classifications as a basis for more accurate rock nomenclature. The research methods included field observations, sample collection, thin section preparation, and petrographic analysis using a polarizing microscope under plane-polarized light (PPL) and cross-polarized light (XPL). The petrographic analysis of 12 samples revealed lithologies consisting of calcareous pelite (slate) and metacarbonate rock (phyllite) within the Tarap Formation (PCt); chert within the Situlanglang Member (Kjgs); chert and andesite within the Insu Member of the Garba Formation (KJgv); lithic tuff, andesite, and basalt within the Kikim Formation (Tpok); ferruginous lithic wacke within the Talang Akar Formation (Tomt); and wackestone limestone within the Baturaja Formation (Tmb). The Gumai Formation (Tmg) is also characterized by calcareous mudrock and wackestone. Overall, the study area is composed of metamorphic, igneous, pyroclastic, and sedimentary rocks, reflecting the diversity of geological processes that have occurred in the region.
References
Boggs, S. Jr. 2009. Petrology of Sedimentary Rocks (2nd Ed.).
Cambridge University Press.
Dunham, R. J. 1962. “Classification of Carbonate Rocks According to Depositional Texture. In W. E. Ham (Ed.), Classification of Carbonate Rocks: A Symposium.” American Association of Petroleum Geologists (AAPG) Memoir 1 108–21.
Embry, A. F., and J. E. Klovan. 1971. “A Late Devonian Reef Tract on Northeastern Banks Island, Northwest Territories.” Bulletin of Canadian Petroleum Geology 10:730–81.
Flügel, E. 2010. Microfacies of Carbonate Rocks: Analysis, Interpretation and Application (2nd Ed.). Springer.
Gafoer, S., T. Amin, and R. Pardede. 1999. “Geologi Lembar Baturaja, Sumatera.” Pusat Penelitian Dan Pengembangan Bandung.
Idarwati, H. S. Purwanto, E. Sutriyono, and C. Prasetyadi. 2018. “Revealing Granitic Basement of Garba Hill, Muara Dua Region, South Sumatera Based on Landsat Images, Structure, and Petrography.” IOP Conference Series: Earth and Environmental Science 212(1). doi: 10.1088/1755- 1315/212/1/012041.
Idarwati, H. S. Purwanto, E. Sutriyono, and C. Prasetyadi. 2021. “The Geologic Process of the Saka River Area: Related to the History Woyla Elevated Ocean in the South Sumatra Island Region, Republic of Indonesia.” Journal of Physics: Conference Series 2117(1). doi: 10.1088/1742- 6596/2117/1/012014.
Idarwati, Budhi Setiawan, Stevanus Nalendra Jati, Yogie Zulkurnia Rochmana, Elisabet Dwi Mayasari, and Muhammad Rendana. 2025. “Schematic Formation of Boudine Granite and Microfold Phyllite of Gilas River: Implications for Triassic to Tertiary Tectonics of Garba Hill, South Ogan Komering Ulu Regency, South Sumatra Province.” Geosystems and Geoenvironment 4(3):100414. doi: 10.1016/j.geogeo.2025.100414.
IUGS. 1989. No TitleA Classification of Igneous Rocks and Glossary of Terms: Recommendations of the International Union of Geological Sciences Subcommission on the Systematics of Igneous Rocks. Oxford: Blackwell Scientific Publications.
Koesoemadinata, R. P. 1981. Klasifikasi Batuan Sedimen. Bandung: Pusat Penelitian dan Pengembangan Teknologi.
Maryanto, Sigit. 2014. “Mikrofasies Dan Diagenesis Batugamping Formasi Baturaja Di Lintasan Air Kiti, Oku, Sumatera Selatan Limestone Microfacies and Diagenesis of Baturaja Formation At Air Kiti Section, Oku, South Sumatra.” Jurnal Geologi Dan Sumberdaya Mineral 15(2):89–104.
Pettijohn, F. J. 1975. Sedimentary Rocks (3rd Ed.). New York: Harper & Row. (628 p.).
Robertson, S. J. 1999. BGS Rock Classification Scheme: Volume 2—Classification of Metamorphic Rocks. British Geological Survey Research Report, RR 99–02. Keyworth, Nottingham, UK: British Geological Survey.
Tucker, M. E. 2001. Sedimentary Petrology: An Introduction to the Origin of Sedimentary Rocks (3rd Ed.).
Blackwell Science.
