Jurnal Ilmiah Geologi Pangea (JIG Pangea) is an Indonesian scientific journal published by the Geological Engineering Department, Faculty of Mineral and Technology, UPN Veteran Yogyakarta. The journal receives Indonesian or English articles. Those articles are selected and reviewed by our professional editors and peer reviewers. The journal is published twice a year every July and December. The published article in JIG Pangea covers all geoscience and technology fields including Geology, Geophysics, Petroleum, Mining, and Geography. The subject covers a variety of topics including : geodynamics, sedimentology and stratigraphy, volcanology, engineering geology, environmental geology, hydrogeology, geo-hazard and mitigation, mineral resources, energy resources, medical geology, geo-archaeology, applied geophysics and geodesy.
PROGRAM STUDI TEKNIK GEOLOGI FAKULTAS TEKNOLOGI MINERAL UPN VETERAN YOGYAKARTA
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Analisis Stabilitas Lereng Disposal Pada Desain In Pit Dump E, Daerah Lawang Kidul, Kabupaten Muara Enim, Sumatra Selatan
Open pit mining for coal requires an effective approach to overburden management, frequently employing in pit dumping (spoil disposal in excavated pits). However, water ponding and mud accumulation at the pit floor are critical variables that increase the potential for slope instability and the risk of landslides. This research aims to quantitatively analyze the stability of the proposed in pit dump design slopes at PT Pamapersada Nusantara, Muara Enim, South Sumatra, focusing on the impact of maximum mud conditions. The stability analysis was conducted using the Limit Equilibrium Method (LEM), specifically the Morgenstern-Price method, applied across six cross-sections. Four sections (A–D) represent the initial design, and two sections (E–F) represent the maximum mud conditions. The calculated Factor of Safety (FS) revealed significant contrasts. Based on the standard set by the Minister of Energy and Mineral Resources Decree No. 1827 K/30/MEM Year 2018 (FS > 1.3), only sections C–C’ (FS = 2.304) and D–D’ (F = 2.271) are classified as safe. Conversely, the four remaining sections (A–A’, B–B’, E–E’, and F–F’) have FS values below the critical threshold of 1.3. Specifically, sections E–E’and F–F’ showed very low FS values, confirming that the presence of mud is the dominant factor causing instability. This indicates that most of the dump slopes are at high risk of failure and categorized as unsafe. Consequently, these analysis results provide a critical foundation for consideration in the planning of future slope geometry redesigns
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Slope Stability Analysis of the Highwall in Coal Mine Pit X, Balangan Regency, South Kalimantan
Coal mining is generally carried out using the open-pit method, which results in the formation of surrounding slopes. Slope stability analysis is essential to determine the safety factor value and prevent potential landslides. This study aims to identify the rock formations and determine the safety factor of the highwall slope in pit “X.” Administratively, the study area is located in Balangan Regency, South Kalimantan Province. The research methodology includes field mapping to obtain primary data on lithology types and orientations, as well as the scanline method on the rock slope to determine the Geological Strength Index (GSI). Secondary data obtained from the company include slope design data, current topography, laboratory test results of rock samples, and groundwater level data. Slope stability analysis was conducted on six cross-sections, from section A–A’ to section F–F’, along the highwall using the Limit Equilibrium Method (LEM) with the Morgenstern-Price approach and the Generalized Hoek-Brown failure criterion. The analysis was performed under both static and dynamic conditions with a horizontal seismic coefficient of 0.05. The results show that all six slope sections have safety factor values greater than 1.3 under static conditions and greater than 1.1 under dynamic conditions, indicating that the slopes are classified as stable.
SLOPE STABILITY ANALYSIS OF DISPOSAL "X" IN AN OPEN-PIT COAL MINING AREA, BALANGAN REGENCY, SOUTH KALIMANTAN
Coal mining activities involve waste material disposal, where slope stability must be maintained to ensure operational safety. This study aims to analyze the slope conditions and determine the factor of safety (FoS) of the disposal slope design to ensure compliance with the minimum safety criteria. The study area is located within the Mining Business Permit (IUP) of PT “Y”, Balangan Regency, South Kalimantan Province. The analysis was conducted using the Limit Equilibrium Method (LEM) with the Morgenstern–Price approach and Mohr–Coulomb failure criterion, utilizing Slide 6.0 software. The data used include actual and 2025 design topography, Standard Penetration Test (SPT) borehole data, geotechnical parameters (cohesion, internal friction angle, and unit weight), and groundwater levels obtained from standpipe piezometers. The results show that all ten analyzed disposal slope sections have FoS values greater than 1.3, indicating that the slopes are stable and suitable for further development.
CHARACTERISTIC OF CRUDE OILS IN MUSI PLATFORM, SOUTH PALEMBANG SUB-BASIN, SOUTH SUMATRA BASIN
Musi Platform located in South Palembang Subbasin, South Sumatra Basin, bounded by Pigi Trough at the north, Saung Naga Graben at the south, and Benakat Gulley at the east. In Musi Platform, there are several oil fields that have been discovered and most of them remain produce oil to this day. Oil type variation discovered in the TG-1 – TG-13 – TG-10 – TG-4 - TG-7 - TG-5 – TG-2 – TG-11 wells. Location of their wells close to each other leads to assumption that they come from same kitchen. Oil analyses were conducted by geochemical analysis including liquid chromatography, gas chromatography, and gas chromatography-mass spectrometry analysis. Oil analysis included 21 samples for carbon isotope and 23 samples for biomarkers. Correlation of crude oil to crude oil, was done by interpreting carbon isotope and biomarkers data. Based on geochemical analysis of crude oil samples, using carbon isotope analysis, oils at research area could be divided into two groups: light saturates and heavy saturates. The light saturates were only found in TG-9, TG-8, TG-7, TG-10, and TG-13 wells, while another well contained heavy saturates. Furthermore, it can be concluded that there are three (3) oil families in the study area, i.e. lacustrine, lacustrine-estuarine, and shallow marine oil families. Lacustrine oil family show C26/C25 (tricyclic terpane) ratio is more than 1, ratio of C31/C30 hopane is smaller than 0.25, carbon isotope δ13C saturates value is -18.70 to -22.08, high C28 sterane concentration, low diasterane concentration. Lacustrine-estuarine oil family show ratio of C26/C25 (tricyclic terpane) is more than 1, ratio of C31/C30 hopane is smaller than 0.25, value of carbon isotope δ13 C saturates -24.24 to -29.1, high C29 sterane concentration, low diasterane concentration. Shallow marine oil family show ratio of C26/C25 (tricyclic terpane) is less than 1, C31/C30 hopane ratio is greater than 0.25, carbon isotope 13 C saturates value is -18.8 to -23.7, high C27 sterane and diasterane concentration.