Petrografi dan Provenance Batupasir Formasi Muara Enim dan Sekitarnya, Kabupaten Lahat, Sumatera Selatan

Abstract

The Muara Enim Formation is a rock formation in the South Sumatra basin that is of late Miocene – Pliocene age which is composed of sandstone, claystone and coal lithologies. The research activity was carried out in Perangai village, Lahat Regency, South Sumatra. This study focuses on petrographic analysis and analysis of rock origin in the Muara Enim formation in sandstone lithology. This research was conducted on sandstone obtained from sandstone outcrops in the research area that have fine sand to coarse sand. From the results of the study of 6 sandstone samples analyzed by petrography, 2 types of Sublitharenite sandstone, 3 types of arcose lithic sandstone, and 1 type of Feldspatic litharenite sandstone according to the Folk Classification, et al. (1970) and based on the results of the provenance analysis of QFL and QmFLt Diagram Dickinson (1983), it was found that the sandstone of the Muara Enim Formation is of high origin which is influenced by the Recycled Orogen tectonic process which shows that the source of the original rock has been affected several times by tectonic activities such as the lifting process and the presence of total quartz mineral content which is more dominating than feldspar and lithik minerals.

Formasi Muara Enim adalah formasi batuan yang ada di cekungan Sumatera Selatan yang beumur Miosen akhir – Pliosen yang tersusun atas litologi batupasir, batulempung dan batubara. Kegiatan penelitian dilakukan didesa Perangai, Kabupaten Lahat, Sumatera Selatan. Penelitian ini berfokus pada analisis petrografi dan analisis asal batuan pada formasi Muara Enim pada litologi batupasir. Penelitian ini dilakukan pada batupasir yang diperoleh dari singkapan batupasir pada daerah penelitian yang memiliki ukuran butir halus sampai dengan kasar. Dari hasil penelitian 6 sampel batupasir yang dianalisis petrografi didapat 2 jenis batupasir Sublitharenite, 3 jenis batupasir Lithic Arkose, dan 1 jenis batupasir Feldspatic litharenite menurut Klasifikasi Folk, dkk (1970) dan berdasarkan hasil analisis provenance presentase QFL dan QmFLt Diagram Dickinson (1983), didapatkan bahwa batupasir Formasi Muara Enim berasal tinggian yang dipengaruhi oleh proses tektonik Recycled Orogen yang menunjukkan bahwa sumber batuan asal telah beberapa kali dipengaruhi oleh aktivitas tektonik seperti proses pengangkatan dan keterdapatan kandungan mineral kuarsa total yang lebih mendominasi dibandingkan mineral feldspar dan lithik.