Skripsi
STUDI LINGKUNGAN PENGENDAPAN DAN ANALISIS KUALITAS BATUBARA BLOK KIKIM, PT. BATUALAM SELARAS
The research was conducted in Gumay Talang District, Lahat Regency, South Sumatra. Regionally, this area is included in the South Sumatra Basin which is a back arc basin. This basin has coal-carrying formations, called the Muaraenim Formation and the Airbenakat Formation. Coal is formed through a sedimentation process that occurs in a specific location called a sedimentation environment. This study’s main goal is to interpret the facies boundaries and to describe the deposition system. Furthermore, this study also analyzed the ash content and total sulfur composition to determine the coal environmental deposition. The research methods used in this research also include lithofacies analysis through measured stratigraphic cross-sections and electrofacies analysis to determine the geophysical log patterns of subsurface rocks and coal quality analysis. Based on geomorphological analysis, the research area has an anthropogenic plateau and concavomorphic landform. The stratigraphy of the research area includes Late Miocene to Pliocene Estuary Enim Formation, which consist of siltstone, claystone, coal, sandstone and carbonaceous claystone layers. Based on geophysical logging, coded DMF-01, DMF-02, DMF-03, and DMF-04 which has 200m interval to one another. The youngest to oldest seam are Seam B, Seam C, Seam D, Seam E. Quality analysis shows that the coal in the study area is classified in the subbituminous B – subbituminous A ranking. The determination of the deposition environment of the research site is based on 4 parameters. Based on the ash content, C seam has the highest ash content, due to visible parting on the C seam. The presence of parting in the coal seam affects the amount of ash content compared to the coal seam that does not have any parting. The presence of parting in the coal seam is caused by flood runoff after coal deposition, after which the coal is redeposited. Based on the sulphur content, the environment of deposition in the study area is classified as upper delta plain. Based on electrofacies, the coal seam has a Cylindrical/Boxcar curve pattern that characterizes the precipitation rate of fluvial channels. Based on the lithology found in the field, the claystone, siltstone, and sandstone comes from fluvial material that deposited in the floodplain – back swamp so that the environment of deposition includes the upper delta plain supported by the presence of clay parting in the coal layer.
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