[en] The Study based on geological setting of Hatapang region, North Sumatera, identified as a favourable area to the formation of sandstone type uranium mineralization. This characterized by the occurred of anomalous radioactivity, uranium contents of the upper cretaceous granite intrusions and radioactivity anomalous of tertiary sedimentary rocks deposited in terrestrial environments. The study is objective to find out the potential formation of sandstone type-uranium mineralization within tertiary sedimentary rocks based on data’s studies of geological, geochemical, mineralogy, radioactivity of rocks. Stratigraphy of Hatapang area of the oldest to youngest are quartz units (permian-carboniferous), sandstone units (upper Triassic), granite (upper cretaceous), conglomerate units (Lower –middle Miocene) and tuff units (Pleistocene). Hatapang’s granite is S type granite which is not only potential as source of radioactive minerals, particularly placer type monazite, but also potential as source rocks of sandstone type-uranium mineralization on lighter sedimentary rocks. Sedimentary rock of conglomerate units has potential as host rock, even though uranium did not accumulated in its rocks since the lack number of carbon as precipitant material and dissolved U"+"6 in water did not reduced into U"+"4 caused the uranium mineralization did not deposited. (author)

[en] Monazite is one source of thorium (Th), which has significant economic value and potential as an alternative fuel of nuclear power plants. The aims of research is to find out the distribution monazite alternative fuel of nuclear power plants. The aims of research is to find out the distribution monazite and its potential as a resource of radioactive minerals on the Bangka Island, then the data will be used and its potential as a resource of radioactive minerals on the Bangka Island, then the data will be used as a reference in the development of radioactive minerals exploration areas in the coming year. The research location is in the Bencah and Gadung villages, South Bangka Regency. The method used is the geological mapping, sampling of rock for petrographic, mineragraphic and autoradiographic analysis and heavy mineral for grains counting analysis. The results showed that lithologic area of Bencah Village composed of clay stone and alluvial deposits, while the Gadung Village composed by granite and alluvial deposits. Granite Gadung is predicted as the ilmenite series granite and tend to be of S type, while the material of Bencah alluvial is predicted come from the Klabat granite groups. In general, distribution of monazite in the alluvial slightly more potent of monazite than in the granite so that the development of radioactive minerals exploration will be prioritized in the alluvial areas. (author)

[en] The Background of this study is due to the geological setting of Harau area and its surrounding, West Sumatera, that is identified as a favourable area for uranium accumulation which is indicated by the presence of anomalous radioactivity in the Tertiary sedimentary rocks deposited on the terrestrial environment and the presence of anomalous uranium contents in Pre-Tertiary granites in several places in West Sumatera, and the presence of radioactivity anomalous in the Pre Tertiary metamorphic rocks. The purpose of this study is to determine the potential formation of uranium mineralization in the Harau area, to be used as a basis to conduct more detailed research in order to inventory the potential of uranium resources in Indonesia. The scope of the discussion in this review includes a discussion of geology, geochemistry and radioactivity of the outcrops. The composition of regional stratigraphic from old to young is quartzite unit, phyllite unit, conglomerate unit, sandstone unit, tuff unit and alluvium river. The main fault that developed in the study area are normal faults trending southwest – northeast. The study area is splitted into two sections where the southeastern part relatives fall down of the northwest. Based on geological setting, radioactivity and uranium data then is assumed that Harau is a potential area for the formation of uranium mineralization in sandstone and its vein type. Sandstone type is expected occur in sandstone conglomerate unit of The Brani Formation and vein type is expected occur in the quartzite unit of The Kuantan Formation. (author)

[en] Rare earth elements (REE) are strategic material used in high-tech and clean energy devices. In Indonesia, REE contained in monazite, zircon, and xenotime minerals as accessories minerals in tin mining located in the granite tin belt of Riau Islands to Bangka Belitung. Singkep is one of the potential areas of REE because its location is in the granite tin belt. The goal of the study is to determine the REE prospects in Singkep Island. The method used by taking 25 pan concentrated samples on some tailing ex tin mining on the Singkep island. These samples were taken from each rock formation on Singkep Island in sequence from older to younger rocks formation, respectively. They are Permian Carboniferous of Bukit Duabelas quartzites, Permian Carboniferous of Persing Metamorphic Rocks, Triassic Muncung granite, Jurassic Tanjungbuku granite, Holocene swamps deposits and alluvium. Each sample of pan concentrated is divided into two parts for REE content and grain mineral analysis. All 25 samples were analyzed for REE content, while only 14 samples for the grain mineral. The results of REE content and grain mineral analysis indicate that the REE prospect area located in the tailings ex tin mining in the rock formation of the Muncung granite area. The highest concentration of lanthanum reached 20100 ppm, cerium 37100 ppm, yttrium 9872 ppm, and neodymium 2840 ppm in monazite, zircon, and allanite. (author)

[en] Geological, radiometrical, and geochemical studies of Banggai granites and Bobong Formation have been conducted in order to obtain potential uranium area. Taliabu Island is selected for the study because Taliabu Island is a micro continent fraction of the Gondwana super continent that separated at the end of the Mesozoic to Paleogene period. Some types of uranium mineralization formed in the period of Gondwana include sandstone-type, lignite coal type, and vein-type. Taliabu Island is a small part from the Gondwana super continent so it is expected will be found uranium mineralization or at least indications of uranium mineralization occurrences. The aim of this study is to obtain uranium potential areas for the development of uranium exploration in the future. The methods used are reviewing geological, radiometric, and geochemical data from various sources. The results of review showed that geological setting, radiometric, and geochemical data gives positive indication to the formation of uranium mineralization for sandstone type. Banggai granite is a potential uranium source. Sandstone of Bobong Formation as a potential host rock. Coal and pyrite as a potential precipitant. Uranium potential area is located on Bobong Formation and its surrounding. (author)

[en] The result of economical study about demand of water supply and electric in Madura Island concludes that in 2016 Madura Island will need nuclear desalination plant to process sea water becomes fresh water. In order to support the installation of nuclear desalination plant, it is required site free from active fault, because active fault is mainly rejection factor criteria on site selection process. Aim of the research is to get geological information and identify of active fault in the site candidate of nuclear desalination plant at Ketapang area and its surrounding by interpretation of aerial photograph and land sat imagery, geological and structure geological mapping as well as trenching. The lithology of Ketapang (Md.01) and Sokobana (Md.02) site candidate consists of reef and chalky limestone forming undulating hills morphology. Structurally, research area forms a monocline with East-West trending axis, plunging 10° to East, the direction of strike is West-East, dip 10° - 30° to North. Geological structure analysis show that research area is free from active fault. (author)

[en] Uranium is a fuel for nuclear power plants at this time and thorium has the potential to become a future nuclear fuel. Utilization of thorium as a nuclear fuel is expected to take place after 2020. Currently research and development of pilot scale thorium-based nuclear power plants is being carried out in several European, American and Asian countries. Thorium is an element found in some of the accessories minerals in several mineral deposits such as tin, bauxite and rare earth elements deposits. Minerals accessories in the mineral deposits are generally monazite. This study aims to provide a genera description of the prospect of thorium in Indonesia, especially for the development of nuclear fuel in the future because in Indonesia there are many tin and bauxite mines, besides that there are also rare earth elements deposits. Result of the preliminary survey in several regions in Indonesia showed that monazite availability in primary tin mines was 5.07 %, secondary tin mines were 7.57 %, bauxite mines were 1.8 % (thorium contents 4,210 ppm), and thorium content in rare earth elements deposits is 86.9 ppm to 11.10 %. The overlay of tin and bauxite and rare earth elements deposits is quite extensive. Tin deposits are located along the zone of granite tin belt from the Riau to Bangka Belitung archipelago. The bauxite deposits is located in the zone of granite tin belt in Riau Islands and West Kalimantan. Rare earth elements deposits located in the area of Mamuju Regency, West Sulawesi. Data occurrences of the monazite or thorium in some mines or mineral deposits in Indonesia and the extent of their dispersion indicate that the prospect of thorium in Indonesia is considered to be quite good. (author)

[en] Ella Ilir administratively located in Melawi Regency, West Kalimantan. Regional geology of Ella Ilir area is composed of metamorphic rocks in Triassic–Carboniferous age which are intruded by Jurassic and Cretaceous granitic rocks. Radioactive minerals occurrences in the area are indicated by magnetite veins radioactivities on Triassic to Carboniferous metamorphic rocks whose values range from 1,000 c/s to 15,000 c/s. Goal of the study is to determine the type of ore mineral deposits and to identify the presence of radioactive mineral in magnetite veins in Ella Ilir area. The methods used are geological mapping, radioactivity measurements, analysis on uranium grades, and mineragraphy analysis of severe magnetite veins samples. Lithologies of the study area are composed by biotite quartzite, meta tuff, metasilt, metapellite, biotite granite, and rhyolite. The east-west sinistral fault and the north-south dextral fault are the developed fault structures in this area. Mineral composition of magnetite veins are consists of iron ore, sulfide, and radioactive minerals. Iron ore mineral consists of magnetite, hematite, and goethite. Sulfide minerals consist of pyrite, pirhotite, and molybdenite, while radioactive minerals consist of uraninite and gummite. The occurrences of magnetite veins are controlled by lithology and geological structures. The magnetite veins in metasilt are thick (1.5–5 m), filled the fractures in the fault zone. Meanwhile, the magnetite veins in metapellite are thinner (milimetric–centimetric), filled the fractures that are parallel to the schistocity. The ore deposits in the study area are iron ore deposits or magnetite ore deposits formed by magmatic hydrothermal processes. (author)

[en] The fieldwork is based on the data of strike (S0) and schistosity (S1) of cores that could not penetrate the geological structure model and result of observation on some cores has shown that U mineralization veins are not always parallel to S1. The problems were encountered in core drill data to improve the estimation of U resources from indication category to measured category. The purpose of the evaluation is to establish the advisability of geological structure model and U mineralization model which was applied by this time. The research used remapping of geological structure with surface method in the scale of 1:1000. The result of remapping shows the difference of the dipping between new geological structure model and the old model. The dipping of the new model is to South East until vertical and the old model is to North West until vertical and to South East until vertical. Despite the difference between both of them, the substantive of folding system is identical so that the new and old models can be applied in drilling in West Lemajung sector. U mineralization model of remapping result consists of 3 types : type 1 U mineralization lens form with West-East direction and vertical dipping which is associated with tourmaline, type 2 U mineralization filling in the open fractures with West-East direction and 70^o to North dipping and parallel with S1, and type 3 U mineralization fill in opening fractures with N 110^o - 130^o E the direction and 60^o to North East until subvertical dipping while the old model is only one type. It is U mineralization filling in the open fractures with West-East the direction and 70^o to North the dipping and parallel with S1. Because of this significant difference, data collection of drill core must follow the new mineralization model. (author)

[en] Thorium and uranium in Bangka Island are mainly found in monazite mineral. In the geological point of view the monazite formed in S type granite, sandstones and alluvial deposits. In Bangka Barat where several S types granite and also alluvial deposits and this area considered as a potential area for monazite placer. S type granites are predicted as a source of monazite while alluvial deposits are considered as a dispersion place for deposition of monazite. The purpose of this study is to determine the geological information and to know the hypothetical potency of thorium and uranium resources in alluvial deposits. The methods used in this study are geological mapping, measurement of thorium and uranium contents in the rock, sampling of granite for petrographic analysis, sampling of heavy mineral in alluvial deposits for grain size analysis. Results of the research show that the lithology of West Bangka region composed of schist unit, meta-sandstone unit, granite intrusion, diabase intrusion, sandstone unit and alluvial deposits. Monazite is found in granite intrusion, sandstone unit and alluvial deposits. Evolving fault strand to northwest-southeast, northeast-southwest and west-east. The results of the grain size analysis of heavy mineral shows the average percentage of monazite in the heavy mineral is 6.34%. Other potential minerals contained in placer deposits are zircon 36.65%, ilmenite 19.67% and cassiterite 14.75%. (author)