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Biomarker Composition of Some Oil Seeps from West Sulawesi, Indonesia Sutadiwiria, Yarra; Hamdani, Ahmad Helman; Sendjaja, Yoga Andriana; Haryanto, Iyan; Yeftamikha, Yeftamikha
Indonesian Journal on Geoscience Vol 5, No 3 (2018)
Publisher : Geological Agency

DOI: 10.17014/ijog.5.3.211-220A suite of oil seep samples collected from the Lariang and Karama Basins, West Sulawesi, Indonesia, have been analyzed using GC and GCMS techniques. Their biomarker compositions have been used to reveal the likely source rock that produces oil. These oil seep samples contain a range in both the concentration of hydrocarbons present and certain level of biodegradation experienced. All sterane m/z 217 data display a familiar pattern of steranes with carbon numbers from 27 to 29 together with pregnane and homo-pregnanes, including rearranged steranes. Triterpane (m/z 191) data show a moderate content of tricyclic terpanes (Tri/C30H), medium to high ratio of norhopane/hopane (C29/C30), and medium to high abundant land plan marker such as resin bicadinanes(Bic/C30H) and oleananes (Ol/C30H). The presence of high abundant oleananes in these samples has been interpreted as the evidence for a marine influence during early diagenesis that may occur by marine or via re-deposition of peat organics in marine sediments. Hence, these results state that the organic matter facies for their source rock oil seep samples from the West Sulawesi region are detected as mixed between allochthonous macerals from typical terrestrial higher plants transported into the basin from distal swamps and soils and some marine organic matter.

Tectonic Control on the Formation of Cleats in the Coal Beds of the Sajau Formation, Berau Basin, Northeast Kalimantan Sudradjat, Adjat; Hamdani, Ahmad Helman
Indonesian Journal on Geoscience Vol 5, No 3 (2018)
Publisher : Geological Agency

DOI: 10.17014/ijog.5.3.235-250Coal seams of lignite- to subbituminous rank of Pliocene-age from the Sajau Formation of the Berau Basin are characterized by the presence of a natural fracture system, including cleats. Often, these opening-mode fractures consist of two orthogonal sets (face and butt cleats), both almost perpendicular to the bedding. This paper describes the distribution of orientation, spacing, and aperture of cleats formed in the seams of the Sajau Formation. All observations and measurements were conducted at macroscopic, mesoscopic, and microscopic scales. The butt cleat mean orientations are NE-SW and NW-SE, whereas the face cleat mean orientations are NNE-SSW and NE-SE, and the cleat dip is at a high angle of 75° to the north. The angles between the orientations of these cleat sets are nearly 90°; that is, they are orthogonal. The spacing of the macroface cleats is between 9.52 and 14.46 cm (averaging 11.61 cm), while the spacing of the butt cleats is between 2.3 and 11.3 cm (averaging 5.35 cm). The mean aperture is 0.54 mm. In contrast, the mean spacing of the mesoface cleats is 3.09 mm, and the aperture measurements of these cleats range from 0.0478 to 0.0741 mm (averaging 0.0549 mm). The results obtained from outcrops and X-ray CT (computed tomography) scan clearly indicate that the NNE-SSW face cleat orientations are strictly parallel to the elongation of the main tectonic structures in the studied area. Their origin may be explained by their relationship with local tectonic stress (the maximum principal stress, σ1, was horizontal). Partial least square analysis of data collected from cleats and faults in the area indicates that a power law distribution exists between the cleat characteristics (spacing, density, and aperture), and the distance of the faults (R2 = 0.56). Cleat formation in the Sajau Formation was mainly controlled by the mechanical response to tectonic stresses, which generated a unique cleat network in the coal. Based on the SEM photography, it is concluded that the development of microcleats in the Sajau Formation resulted from both endogenic processes and tectonic activities as indicated by the change in the shape of the cleats, from straight line to curved shape and branching (intersection of multiple cleats that form a conical network at the end).

Biomarker Composition of Some Oil Seeps from West Sulawesi, Indonesia Sutadiwiria, Yarra; Hamdani, Ahmad Helman; Sendjaja, Yoga Andriana; Haryanto, Iyan; Yeftamikha, Yeftamikha
Indonesian Journal on Geoscience Vol 5, No 3 (2018)
Publisher : Geological Agency

DOI: 10.17014/ijog.5.3.211-220A suite of oil seep samples collected from the Lariang and Karama Basins, West Sulawesi, Indonesia, have been analyzed using GC and GCMS techniques. Their biomarker compositions have been used to reveal the likely source rock that produces oil. These oil seep samples contain a range in both the concentration of hydrocarbons present and certain level of biodegradation experienced. All sterane m/z 217 data display a familiar pattern of steranes with carbon numbers from 27 to 29 together with pregnane and homo-pregnanes, including rearranged steranes. Triterpane (m/z 191) data show a moderate content of tricyclic terpanes (Tri/C30H), medium to high ratio of norhopane/hopane (C29/C30), and medium to high abundant land plan marker such as resin bicadinanes(Bic/C30H) and oleananes (Ol/C30H). The presence of high abundant oleananes in these samples has been interpreted as the evidence for a marine influence during early diagenesis that may occur by marine or via re-deposition of peat organics in marine sediments. Hence, these results state that the organic matter facies for their source rock oil seep samples from the West Sulawesi region are detected as mixed between allochthonous macerals from typical terrestrial higher plants transported into the basin from distal swamps and soils and some marine organic matter.

Tectonic Control on the Formation of Cleats in the Coal Beds of the Sajau Formation, Berau Basin, Northeast Kalimantan Sudradjat, Adjat; Hamdani, Ahmad Helman
Indonesian Journal on Geoscience Vol 5, No 3 (2018)
Publisher : Geological Agency

DOI: 10.17014/ijog.5.3.235-250Coal seams of lignite- to subbituminous rank of Pliocene-age from the Sajau Formation of the Berau Basin are characterized by the presence of a natural fracture system, including cleats. Often, these opening-mode fractures consist of two orthogonal sets (face and butt cleats), both almost perpendicular to the bedding. This paper describes the distribution of orientation, spacing, and aperture of cleats formed in the seams of the Sajau Formation. All observations and measurements were conducted at macroscopic, mesoscopic, and microscopic scales. The butt cleat mean orientations are NE-SW and NW-SE, whereas the face cleat mean orientations are NNE-SSW and NE-SE, and the cleat dip is at a high angle of 75Â° to the north. The angles between the orientations of these cleat sets are nearly 90Â°; that is, they are orthogonal. The spacing of the macroface cleats is between 9.52 and 14.46 cm (averaging 11.61 cm), while the spacing of the butt cleats is between 2.3 and 11.3 cm (averaging 5.35 cm). The mean aperture is 0.54 mm. In contrast, the mean spacing of the mesoface cleats is 3.09 mm, and the aperture measurements of these cleats range from 0.0478 to 0.0741 mm (averaging 0.0549 mm). The results obtained from outcrops and X-ray CT (computed tomography) scan clearly indicate that the NNE-SSW face cleat orientations are strictly parallel to the elongation of the main tectonic structures in the studied area. Their origin may be explained by their relationship with local tectonic stress (the maximum principal stress, Ïƒ1, was horizontal). Partial least square analysis of data collected from cleats and faults in the area indicates that a power law distribution exists between the cleat characteristics (spacing, density, and aperture), and the distance of the faults (R2 = 0.56). Cleat formation in the Sajau Formation was mainly controlled by the mechanical response to tectonic stresses, which generated a unique cleat network in the coal. Based on the SEM photography, it is concluded that the development of microcleats in the Sajau Formation resulted from both endogenic processes and tectonic activities as indicated by the change in the shape of the cleats, from straight line to curved shape and branching (intersection of multiple cleats that form a conical network at the end).

Biomarker Composition of Some Oil Seeps from West Sulawesi, Indonesia Sutadiwiria, Yarra; Hamdani, Ahmad Helman; Sendjaja, Yoga Andriana; Haryanto, Iyan; Yeftamikha, Yeftamikha
Indonesian Journal on Geoscience Vol 5, No 3 (2018)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.5.3.211-220

DOI: 10.17014/ijog.5.3.211-220A suite of oil seep samples collected from the Lariang and Karama Basins, West Sulawesi, Indonesia, have been analyzed using GC and GCMS techniques. Their biomarker compositions have been used to reveal the likely source rock that produces oil. These oil seep samples contain a range in both the concentration of hydrocarbons present and certain level of biodegradation experienced. All sterane m/z 217 data display a familiar pattern of steranes with carbon numbers from 27 to 29 together with pregnane and homo-pregnanes, including rearranged steranes. Triterpane (m/z 191) data show a moderate content of tricyclic terpanes (Tri/C30H), medium to high ratio of norhopane/hopane (C29/C30), and medium to high abundant land plan marker such as resin bicadinanes(Bic/C30H) and oleananes (Ol/C30H). The presence of high abundant oleananes in these samples has been interpreted as the evidence for a marine influence during early diagenesis that may occur by marine or via re-deposition of peat organics in marine sediments. Hence, these results state that the organic matter facies for their source rock oil seep samples from the West Sulawesi region are detected as mixed between allochthonous macerals from typical terrestrial higher plants transported into the basin from distal swamps and soils and some marine organic matter.

Tectonic Control on the Formation of Cleats in the Coal Beds of the Sajau Formation, Berau Basin, Northeast Kalimantan Sudradjat, Adjat; Hamdani, Ahmad Helman
Indonesian Journal on Geoscience Vol 5, No 3 (2018)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.5.3.235-250

DOI: 10.17014/ijog.5.3.235-250Coal seams of lignite- to subbituminous rank of Pliocene-age from the Sajau Formation of the Berau Basin are characterized by the presence of a natural fracture system, including cleats. Often, these opening-mode fractures consist of two orthogonal sets (face and butt cleats), both almost perpendicular to the bedding. This paper describes the distribution of orientation, spacing, and aperture of cleats formed in the seams of the Sajau Formation. All observations and measurements were conducted at macroscopic, mesoscopic, and microscopic scales. The butt cleat mean orientations are NE-SW and NW-SE, whereas the face cleat mean orientations are NNE-SSW and NE-SE, and the cleat dip is at a high angle of 75Â° to the north. The angles between the orientations of these cleat sets are nearly 90Â°; that is, they are orthogonal. The spacing of the macroface cleats is between 9.52 and 14.46 cm (averaging 11.61 cm), while the spacing of the butt cleats is between 2.3 and 11.3 cm (averaging 5.35 cm). The mean aperture is 0.54 mm. In contrast, the mean spacing of the mesoface cleats is 3.09 mm, and the aperture measurements of these cleats range from 0.0478 to 0.0741 mm (averaging 0.0549 mm). The results obtained from outcrops and X-ray CT (computed tomography) scan clearly indicate that the NNE-SSW face cleat orientations are strictly parallel to the elongation of the main tectonic structures in the studied area. Their origin may be explained by their relationship with local tectonic stress (the maximum principal stress, Ïƒ1, was horizontal). Partial least square analysis of data collected from cleats and faults in the area indicates that a power law distribution exists between the cleat characteristics (spacing, density, and aperture), and the distance of the faults (R2 = 0.56). Cleat formation in the Sajau Formation was mainly controlled by the mechanical response to tectonic stresses, which generated a unique cleat network in the coal. Based on the SEM photography, it is concluded that the development of microcleats in the Sajau Formation resulted from both endogenic processes and tectonic activities as indicated by the change in the shape of the cleats, from straight line to curved shape and branching (intersection of multiple cleats that form a conical network at the end).

Biomarker Composition of Some Oil Seeps from West Sulawesi, Indonesia Yarra Sutadiwiria; Ahmad Helman Hamdani; Yoga Andriana Sendjaja; Iyan Haryanto; Yeftamikha Yeftamikha
Indonesian Journal on Geoscience Vol 5, No 3 (2018)
Publisher : Geological Agency

DOI: 10.17014/ijog.5.3.211-220A suite of oil seep samples collected from the Lariang and Karama Basins, West Sulawesi, Indonesia, have been analyzed using GC and GCMS techniques. Their biomarker compositions have been used to reveal the likely source rock that produces oil. These oil seep samples contain a range in both the concentration of hydrocarbons present and certain level of biodegradation experienced. All sterane m/z 217 data display a familiar pattern of steranes with carbon numbers from 27 to 29 together with pregnane and homo-pregnanes, including rearranged steranes. Triterpane (m/z 191) data show a moderate content of tricyclic terpanes (Tri/C30H), medium to high ratio of norhopane/hopane (C29/C30), and medium to high abundant land plan marker such as resin bicadinanes(Bic/C30H) and oleananes (Ol/C30H). The presence of high abundant oleananes in these samples has been interpreted as the evidence for a marine influence during early diagenesis that may occur by marine or via re-deposition of peat organics in marine sediments. Hence, these results state that the organic matter facies for their source rock oil seep samples from the West Sulawesi region are detected as mixed between allochthonous macerals from typical terrestrial higher plants transported into the basin from distal swamps and soils and some marine organic matter.

Tectonic Control on the Formation of Cleats in the Coal Beds of the Sajau Formation, Berau Basin, Northeast Kalimantan Adjat Sudradjat; Ahmad Helman Hamdani
Indonesian Journal on Geoscience Vol 5, No 3 (2018)
Publisher : Geological Agency

DOI: 10.17014/ijog.5.3.235-250Coal seams of lignite- to subbituminous rank of Pliocene-age from the Sajau Formation of the Berau Basin are characterized by the presence of a natural fracture system, including cleats. Often, these opening-mode fractures consist of two orthogonal sets (face and butt cleats), both almost perpendicular to the bedding. This paper describes the distribution of orientation, spacing, and aperture of cleats formed in the seams of the Sajau Formation. All observations and measurements were conducted at macroscopic, mesoscopic, and microscopic scales. The butt cleat mean orientations are NE-SW and NW-SE, whereas the face cleat mean orientations are NNE-SSW and NE-SE, and the cleat dip is at a high angle of 75° to the north. The angles between the orientations of these cleat sets are nearly 90°; that is, they are orthogonal. The spacing of the macroface cleats is between 9.52 and 14.46 cm (averaging 11.61 cm), while the spacing of the butt cleats is between 2.3 and 11.3 cm (averaging 5.35 cm). The mean aperture is 0.54 mm. In contrast, the mean spacing of the mesoface cleats is 3.09 mm, and the aperture measurements of these cleats range from 0.0478 to 0.0741 mm (averaging 0.0549 mm). The results obtained from outcrops and X-ray CT (computed tomography) scan clearly indicate that the NNE-SSW face cleat orientations are strictly parallel to the elongation of the main tectonic structures in the studied area. Their origin may be explained by their relationship with local tectonic stress (the maximum principal stress, σ1, was horizontal). Partial least square analysis of data collected from cleats and faults in the area indicates that a power law distribution exists between the cleat characteristics (spacing, density, and aperture), and the distance of the faults (R2 = 0.56). Cleat formation in the Sajau Formation was mainly controlled by the mechanical response to tectonic stresses, which generated a unique cleat network in the coal. Based on the SEM photography, it is concluded that the development of microcleats in the Sajau Formation resulted from both endogenic processes and tectonic activities as indicated by the change in the shape of the cleats, from straight line to curved shape and branching (intersection of multiple cleats that form a conical network at the end).

ANALISIS PENENTUAN JARAK TITIK INFORMASI DAN KLASIFIKASI SUMBER DAYA ENDAPAN NIKEL LATERIT BERDASARKAN ANALISIS VARIOGRAM Irfan Marwanza; Chairul Nas; Theresa Naomi Putri; Ahmad Helman Hamdani; Iyan Haryanto
JURNAL GEOMINERBA (JURNAL GEOLOGI, MINERAL DAN BATUBARA) Vol 1 No 1 (2017): Jurnal Geominerba - 2017
Publisher : PPSDM Geominerba

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.58522/ppsdm22.v1i1.120

Estimation process of precipitated mineral deposit is usually done by using conventional method which is only based on sample position. The accurate estimation method, that includes spatial and temporal continuity, is considered important, and a method that takes account of this continuity is Kriging Method. A study will be conducted by making laterite nickel zonation, based on degree of drill core (coring), while content appraisal and nickel resource comparison in block model will use Kriging Method. Data of this study is taken from southern block exploration of PT. Haltim, Wailukum, district of East Halmahera, North Maluku. Description method isused to analyse assay data, lithology, collar, and bore hole survey. Analysis method is done by using Surpac 6.3 software. Through block model result, it is found that the spread of nickel, ferrum, MgO, SiO2 and cobalt is in every percentage of the level. This method will generate experimental Variogram using lag value, nugget effect and sill that should be taken into account to make an accurate estimation result. The classification is done based on thickness and weighting of saprolite zone in southern block. The result of classification using sill method for saprolite zone is one third sill for measuring area of 35 meter, and two third sill for appointed area of 55 meter. For that reason, in this study area, for 50 meter gap of bore hole is classified as appointed area.

NILAI KUALITAS MASSA BATUAN DENGAN METODE ROCK MASS RATING PADA AREA LOWWALL PIT X, PT. BUKIT ASAM TBK. SUMATERA SELATAN Dandy, Leonardus; Khoirullah, Nur; Hamdani, Ahmad Helman
JURNAL GEOMINERBA (JURNAL GEOLOGI, MINERAL DAN BATUBARA) Vol 8 No 2 (2023): Jurnal Geominerba - 2023
Publisher : PPSDM Geominerba

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.58522/ppsdm22.v8i2.139

This research is located in the Muara Enim Formation which is included in the South Sumatera Basin and this formation is a coal-bearing formation in the study area. Rock Mass Rating classification is a rock mass classification method which can be used as an initial reference for engineering geology because it describes the rock mass characteristics which assosiated with slope stability. Mining at PT Bukit Asam, Tbk. using the open pit mining method so the control process is related to slope stability. The research was conducted on lowwall slope area which was designed to follow the slope of the rock layers that have the potential for plane slides so it is important to know the characteristics of the rock mass as an initial reference for the stability of a slope. The quality of the rock mass rating is determined by the rating of each parameter which is carried out by using the scanline method as a field calculation. Based on the rating of rock mass rating, the study area is divided into three rock mass classes, rock mass class II (good rock), rock mass class III (fair rock), and rock mass class IV (poor rock).

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