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Andri Agus Rahman
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INDONESIA
Eksplorium : Buletin Pusat Pengembangan Bahan Galian Nuklir
ISSN : 08541418     EISSN : 2503426X     DOI : https://doi.org/10.55981/eksplorium
EKSPLORIUM is published to deliver the results of studies, research and development in the field of nuclear geology. The manuscripts are the result of study, research and development of nuclear geology with scope: geology, exploration, mining, nuclear minerals processing, safety and environment, and development of nuclear technology for the welfare.
Articles 172 Documents
Tectonic Pattern Imaging of Southern Sumatra Region Using Double Difference Seismic Tomography Firmansyah, Akmal; Wandono; Ramdhan, Mohamad
EKSPLORIUM Vol. 43 No. 1 (2022): MAY 2022
Publisher : BRIN Publishing

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17146/eksplorium.2022.43.1.6603

Abstract

Southern Sumatra and its surroundings are close to the contact zone of the Indo-Australian plate and Eurasian plate, so the area always relates to the high seismicity zone. The Sumatran subduction zone, the Mentawai fault, and several segments of the Sumatran fault drive seismic activities in the area. Tectonic settings are essential to understanding the area's source and hazard. This understanding can be obtained using the relocated hypocenter distribution and the 3D velocity model in the area. Relocated hypocenters and velocity models are obtained from simultaneous inversion from the BMKG earthquake catalog in January 2012-December 2020 using the double difference seismic tomography method. Seismic velocity inversion of P- and S- wave tomograms image the thermal zone beneath Dempo and Patah volcanoes at a depth of 30-50 km. Slab dehydration is also observed in several forearc high zone. Both phenomena are associated with negative anomalies. The Sumatran and Mentawai fault zones are marked between negative and positive anomalies on the contact zone. The subducted slab of the Indo-Australian plate is observed until a depth of 150 km, which is the maximum depth of nodes used in this study. The granitic basement beneath Anak Krakatau volcano is detected until 10 km. Two of those geological features are related to positive anomalies.
Geostatistical Ore Body Modeling on Uranium Mineralization in Remaja Sector, Kalan Area, West Kalimantan Ciputra, Roni Cahya; Heriawan, Mohamad Nur; Syaeful, Heri; Kamajati, Dhatu; Rahmawati, Putri
EKSPLORIUM Vol. 43 No. 1 (2022): MAY 2022
Publisher : BRIN Publishing

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17146/eksplorium.2022.43.1.6622

Abstract

Manual ore body modeling on Remaja Sector, Kalan, West Kalimantan generally takes a long time and is subjective. On the other hand, automatic modeling (implicit modeling) is faster, objective, and equipped with uncertainty factors. This study aimed to analyze the comparison between the geostatistical Sequential Indicator Simulation (SIS) ore body model to the manual ore body model. The lithology database was used as input for variogram analysis and SIS simulation. The directional variogram was used to construct an experimental variogram for the lithology with orientation data. The orientation of the lithologies corresponds to the anisotropy of their variogram map. The SIS was carried out in Block A and Block B with block sizes of 6×6×6 m3 and 5×5×5 m3 respectively. The simulation results were processed to produce a lithology probability model. By using maximum probability as block lithology, simulation results were well validated by the composite database histogram, the lithologies along the tunnel on the geological map of level 450 masl of Eko Remaja Tunnel., and the lithologies along boreholes. The weakness of the geostatistical ore body model was the results depending on the input parameters. Meanwhile, several advantages of the geostatistical ore body model were a faster processing process, equipped with an uncertainty factor, and the block size of the model has taken into account the distance between grade data so that it can be used directly for grade estimation. Quantitatively, the geostatistical ore body model had a higher average percentage of conformity to the lithology of the mineralized zone along the borehole than the manual ore body model
Volcanic Ash Fall Hazard of Mount Merapi on Yogyakarta Nuclear Area Setiaji, Abimanyu Bondan Wicaksono; Satyarno, Iman; Harijoko, Agung
EKSPLORIUM Vol. 43 No. 2 (2022): NOVEMBER 2022
Publisher : BRIN Publishing

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17146/eksplorium.2022.43.2.6708

Abstract

The existence of nuclear installations in the Yogyakarta Nuclear Area is vulnerable to the eruption of Mount Merapi, the most active volcano in Indonesia. Tephra hazard has the potential to threaten the operational activities of nuclear installations in the Yogyakarta Nuclear Area; thus, it is necessary to analyze the distribution and potential hazard of volcanic ash from Mount Merapi for future eruptions. Numerical modelling is used in analyzing tephra distribution using TEPHRA2 software with parameters of the 2010 Mount Merapi eruption, which is then visualized to isomass and isopach maps of tephra distribution. The analysis resulted in the ash dispersion leading to the Yogyakarta Nuclear Area in April, May, June, and August with an accumulated mass of 20-50 kg/m3 with a thickness of 0.2-12 cm. It is necessary to deal with volcanic ash hazards such as roof strength, secondary cooling system, filtering system, and electrical system for several installations in the Yogyakarta Nuclear Area.
Geology and Alteration of East Pinolosian Area, Bolaang Mongondow, North Sulawesi Province Mardain, Tober; Arifin, Yayu Indriati; Kasim, Muhamad; Rosadi, Dhani Rhamdani
EKSPLORIUM Vol. 43 No. 2 (2022): NOVEMBER 2022
Publisher : BRIN Publishing

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17146/eksplorium.2022.43.2.5835

Abstract

Bolaang Mongondow is located on the Eastern North arm of Sulawesi. This area is a Neogene-aged magmatic arc composed of plutonic and volcanic rocks that indicate mineralization-bearing host rocks. The study aimed to determine the geological setting and alteration based on geological observations and geochemical analysis. The method used is geological mapping, followed by laboratory and studio data analysis. The lithology of this area is composed of andesite, diorite, and pyroclastic breccia units. Two main faults are the Northwest-Southeast trending dextral fault and the Northeast-Southwest trending sinistral fault, which causes hydrothermal mineral alteration. Mineral alteration in the study area is divided into several zones, including the Silicification Zone (massive silica + vuggy silica), Advance Argillic Zone (illite + alunite + dickite + halloysite + kaolinite), Argillic Zone (illite + montmorillonite + pyrophyllite), Prophyllitic Zone (chlorite + montmorillonite). The presence of mineral assemblages and alteration zones shows the characteristics of High Sulfide Epithermal deposits with the highest level of 0.47/ppm in the Advance Argillic Zone.
Petrogenesis and Geological Structure of Tantan Granitoid in Sungai Manau District, Merangin Regency, Jambi Province Ariani, Rizky Putri; Utama, Hari Wiki
EKSPLORIUM Vol. 43 No. 2 (2022): NOVEMBER 2022
Publisher : BRIN Publishing

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17146/eksplorium.2022.43.2.6415

Abstract

Tantan granitoids are Late Triassic–Early Jurassic age intrusive rocks that are quite extensive and can be partially found in Sungai Manau Sub-district, Merangin Regency, Jambi Province. Tantan granitoids are found in the Barisan Hills physiography, a magmatic arc line on Sumatra Island. Tantan granitoids are interesting to observe to explain rock formation. The petrographic and XRF analyses can provide insight into the intrusive rock type, its relationship to the tectonic framework, and magmatism. The trend of potential mineral resources can be interpreted based on the granitoid-type approach. The Tantan Granitoid Intrusion has two types of rocks: granite and quartz monzodiorite. Granite and quartz monzodiorite are sub-alkaline magma types, with the granitoid type being I-type metaluminous, which tends to have potential with base metal minerals associated with hornblende minerals from observations or petrographic analysis. Based on the TAS diagram of Na2O+K2O vs. SiO2 shows that the sub-alkaline magma type is a calc-alkaline series type in the K2O vs. SiO2 diagram and a calc-alkaline type in the AFM diagram. This data analysis shows that the tectonic formation of the Tantan Granitoid magma was formed from orogenic results in the form of a Continental Arc. This type can be associated with Meso-Thetic subduction activities against the West Sumatra Sundablock during the Late Triassic–Early Jurassic. Structures in the study area include northwest-southeast trending horizontal faults, including Batang Tantan Fault, Tiangko Fault, Sei Tengko Fault, and Serik Fault, then northeast–southwest trending regional faults, and relatively downward trending faults, namely Serik Fault and Betung Fault. The formation of fault structures is believed to result from subduction tectonic processes during this period.
Geological Structure Control on the Formation of Metal Mineralization at Quartz Veins in Jendi Village, Wonogiri Regency, Central Java Widagdo, Asmoro; Sukadana, I Gde; Indrastomo, Frederikus Dian
EKSPLORIUM Vol. 43 No. 2 (2022): NOVEMBER 2022
Publisher : BRIN Publishing

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17146/eksplorium.2022.43.2.6623

Abstract

Quartz veins in the Jendi area and its surroundings are formed by geological structures with distributions and patterns that need to be known. This study uses data on striation, quartz vein orientation, and metal content in quartz veins. The use of this data aims to determine the relationship between the vein direction pattern and its metal mineral content with the main structure that forms it. The results of this study can be useful in determining the structural model and distribution of veins in the study area. The research method was carried out through a series of field and laboratory work. Fieldwork includes measuring striation data, measuring the orientation of quartz veins, and taking quartz vein samples. Studio work includes stereographic analysis of striation data, rosette diagram analysis of vein measurement data, and analysis of metallic element content of quartz veins. The quartz vein mineralization zone in the study area is controlled by a right slip fault with a northwest-southeast trend that forms a transtension zone with a north-south trend. The north-south trending veins are generally thick, long/continuous, and have a high metal content.
Activation of Kaolin Minerals from Ketapang Regency as Cu Metal Adsorbent Material Septiansyah, Sy. Indra; Afandi, Idris Herkan; Dirtami, Retno Tasya
EKSPLORIUM Vol. 43 No. 2 (2022): NOVEMBER 2022
Publisher : BRIN Publishing

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17146/eksplorium.2022.43.2.5802

Abstract

Kaolin is a term given to a group of phyllosilicate minerals whose layers have a 1:1 structure with Al2Si2O5(OH)4 composition. This type of kaolin phyllosilicate mineral is commonly known as a clay mineral. The kaolin clay group consists mainly of the kaolinite mineral or better known as white clay. Kaolin is widely applied in industries such as paper, ceramics, rubber, plastic, paint, fiberglass, cosmetics, etc. The processing of kaolin as an adsorbent can be carried out using physical activation, where the kaolin is washed and separated from the impurities and dried into a powder. Then the chemical activation of kaolin will go through a leaching process using HCl with optimal concentrations aimed at separating kaolin from impurities that are still chemically bound to kaolin. The results of the characteristics show recovery of 71.42% to 81.2% and moisture content <2%. The chemical composition of kaolin containing SiO2 was 53.32–67.32%, Al2O3 was 28.22–30.47%, Fe2O3 was 1.32%, CaO was 0.03%, MgO was 0.20%, MnO2 was 0.01%, K2O of 0.86%, NaO of 0.01%, Cr of 0.01%, LOI of 11.03%. The adsorption test results on Cu metal in CuSO4 solution showed the absorption of 62–93% of Cu metal which was adsorption.
Distribution and Characteristics of Rare Earth Elements in Uranium-Ore Deposits from Rirang Area, West Kalimantan Province, Indonesia Adimedha, Tyto Baskara; Farenzo, Rayhan Aldizan; Sukadana, I Gde; Nugraheni, Rosmalia Dita; Pratiwi, Fadiah; Ciputra, Roni Cahya; Indrastomo, Frederikus Dian; Syaeful, Heri; Rachael, Yoshi
EKSPLORIUM Vol. 45 No. 1 (2024): MAY 2024
Publisher : BRIN Publishing

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.55981/eksplorium.2024.7058

Abstract

Uranium and rare earth elements (REE) are essential elements for the development of green environmentally friendly, and sustainable energy. To meet the increasing demand for these raw materials, Indonesia has taken steps to explore and map potential deposits, including the Rirang Sector in Melawi Regency, West Kalimantan. However, the available information on the mineralization of these elements in the area is limited. Therefore, this study aimed to provide a detailed characterization on the petrology and geochemical characteristics of uranium ore and to synthesize the mineral genesis of uranium and REE-bearing ore in the Rirang Sector. The analytical methods used included petrography, micro-XRF, and geochemical analysis. The results showed that uranium mineralization was present in brannerites, uranophane, and swamboite associated with tourmaline and monazite ore. Similarly, REE concentrations were hosted by REE-bearing minerals, such as monazite, xenotime, and loparite. Geochemically, the uranium concentration in the monazite ore ranged from 1,110 – 28,440 ppm, while the total REE (TREE) concentration varied between 85,320 to 138,488 ppm. The formation of uranium and REE mineralization were due to the metasomatism process and its association with the Na-rich fluid of felsic intrusion. Notably, the weathering process did not enrich uranium and REE content in the soil but rather decreased it due to the leaching process and the absence of clay minerals capable of absorbing the REE cations on the surface of clay crystal structures.
Characterization of Radioactive and Rare Earth Elements in Heavy Minerals from River Sediments in Marau Region, Ketapang, West Kalimantan Pratiwi, Fadiah; Rachael, Yoshi; Widodo; Fauzi, Rachman; Madyaningarum, Nunik; Adimedha, Tyto Baskara; Indrastomo, Frederikus Dian; Sukadana, I Gde
EKSPLORIUM Vol. 45 No. 1 (2024): MAY 2024
Publisher : BRIN Publishing

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.55981/eksplorium.2024.6971

Abstract

Alluvium deposits from the Kendawangan River located in Marau, Ketapang, West Kalimantan have been known for their radioactive and rare earth mineral potential. In this paper, heavy minerals taken from alluvium deposits will be characterized to determine the elemental distribution of uranium, thorium, and rare earth elements in each mineral and their mineralogical composition. The samples are taken by panning and prepared using the flotation method to obtain heavy mineral concentrates. Geochemical analysis was carried out using a Bruker M4 Tornado plus Micro-XRF and continued with mineralogical analysis using AMICS (Advanced Mineral Identification and Characterization System) software. It was found that the distribution of heavy minerals from the sand samples was dominated by manganoan ilmenite, ilmenite, rutile, zircon, magnetite, and monazite, as well as thorite, cassiterite, xenotime, allanite, and other minerals in small quantities. Uranium, thorium, and rare earth elements are found in monazite, thorite, xenotime, zircon, and allanite.
Geological Structure Identification Using GGMplus Satellite Gravity Data in The Area Surrounding Mount Tampomas Mazzaluna, Haidar Prida; Rustadi; Wibowo, Rahmat Catur
EKSPLORIUM Vol. 45 No. 1 (2024): MAY 2024
Publisher : BRIN Publishing

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.55981/eksplorium.2024.6924

Abstract

Satellite gravity provides a new alternative in geological exploration with several advantages, such as low operational cost and large covering area. GGMplus satellite gravity data provide better accuracy for several applications such as lithology or fault identification. Satellite gravity provides a new alternative in geological exploration with several advantages, such as lower costs, broader area coverage, and easily accessible data. Mount Tampomas is one of the areas that has geothermal prospects and a mountain area that has many types of rock formations and faults. This research has been conducted using GGMplus satellite gravity data in the Mount Tampomas area to obtain the second vertical derivative (SVD) and identify the fault distribution in the area. The GGMplus Gravity Acceleration data was corrected and filtered to obtain SVD structures in the area. The structure in this area is dominantly trending northwest-southeast and west-east. The area around Mount Tampomas forms a structure in the form of a caldera. In addition, there are also structures trending north-south at coordinates 81500-82000 E. Some of these structures were overlaid with a geological map to see the suitability of the processed data with the geological conditions that have been studied. The comparison is done by overlaying the structure of the interpretation results and the contour of the value 0 from the Second Vertical Derivative (SVD) data so that we get four fault structures that correlate with the geological map, three calderas, and one lineament that correlates with the lineament map.