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INDONESIA
Indonesian Journal on Geoscience
Published by Geological Agency Ministry of Energy and Mineral Resources
ISSN : 23559314     EISSN : 23559306     DOI : https://doi.org/10.17014/ijog.3.2.77-94
Core Subject : Science,
Earth & Planetary Sciences
The spirit to improve the journal to be more credible is increasing, and in 2012 it invited earth scientists in East and Southeast Asia as well as some western countries to join the journal for the editor positions in the Indonesia Journal of Geology. This is also to realize our present goal to internationalize the journal, The Indonesian Journal on Geoscience, which is open for papers of geology, geophysics, geochemistry, geodetics, geography, and soil science. This new born journal is expected to be published three times a year. As an international publication, of course it must all be written in an international language, in this case English. This adds difficulties to the effort to obtain good papers in English to publish although the credit points that an author will get are much higher. This Journal publishes 3 numbers per year at least 15 articles. It is a challenge for the management of the journal to remain survive and at the same time continuously maintain its quality and credibility in spite of those various constraints. Fortunately, this effort is strongly supported by the Geological Agency of Indonesia, as the publisher and which financially bear the journal. Last but not least the journal is also managed by senior geologist of various subdisciplines from various countries who are responsible for its quality.
Arjuna Subject : Ilmu Bumi dan Planet (semua kategori) - Geologi
Articles 323 Documents
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Hydrogeological Model of an Urban City in a Coastal Area, Case study: Semarang, Indonesia Putranto, Thomas; Rüde, Thomas
Indonesian Journal on Geoscience Vol 3, No 1 (2016)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.3.1.17-27

Abstract

DOI:10.17014/ijog.3.1.17-27In Semarang City, groundwater has been exploited as a natural resource since 1841. The groundwater exploited in deep wells is concentrated in confined aquifers. The previous hydrogeological model was developed in one unit of aquifer and refined then by using several hydrostratigraphical units following a regional hydrogeological map without any further analysis. At present, there is a lack of precise hydrogeological model which integrates geological and hydrogeological data, in particular for multiple aquifers in Semarang. Thus, the aim of this paper is to develop a hydrogeological model for the multiple aquifers in Semarang using an integrated data approach. Groundwater samples in the confined aquifers have been analyzed to define the water type and its lateral distribution. Two hydrogeological cross sections were then created based on several borelog data to define a hydrostratigraphical unit (HSU). The HSU result indicates the hydrogeological model of Semarang consists of two aquifers, three aquitards, and one aquiclude. Aquifer 1 is unconfined, while Aquifer 2 is confined. Aquifer 2 is classified into three groups (2a, 2b, and 2c) based on analyses of major ion content and hydrostratigraphical cross sections.
Stratified Sampling to Define Levels of Petrographic Variation in Coal Beds: Examples from Indonesia and New Zealand Moore, Tim A.
Indonesian Journal on Geoscience Vol 3, No 1 (2016)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.3.1.29-51

Abstract

DOI: 10.17014/ijog.3.1.29-51Stratified sampling of coal seams for petrographic analysis using block samples is a viable alternative to standard methods of channel sampling and particulate pellet mounts. Although petrographic analysis of particulate pellets is employed widely, it is both time consuming and does not allow variation within sampling units to be assessed - an important measure in any study whether it be for paleoenvironmental reconstruction or in obtaining estimates of industrial attributes. Also, samples taken as intact blocks provide additional information, such as texture and botanical affinity that cannot be gained using particulate pellets. Stratified sampling can be employed both on ‘fine’ and ‘coarse’ grained coal units. Fine-grained coals are defined as those coal intervals that do not contain vitrain bands greater than approximately 1 mm in thickness (as measured perpendicular to bedding). In fine-grained coal seams, a reasonable sized block sample (with a polished surface area of ~3 cm2) can be taken that encapsulates the macroscopic variability. However, for coarse-grained coals (vitrain bands >1 mm) a different system has to be employed in order to accurately account for the larger particles. Macroscopic point counting of vitrain bands can accurately account for those particles>1 mm within a coal interval. This point counting method is conducted using something as simple as string on a coal face with marked intervals greater than the largest particle expected to be encountered (although new technologies are being developed to capture this type of information digitally). Comparative analyses of particulate pellets and blocks on the same interval show less than 6% variation between the two sample types when blocks are recalculated to include macroscopic counts of vitrain. Therefore even in coarse-grained coals, stratified sampling can be used effectively and representatively.
Coral Reef Development as an Indicator of Seal Level Fluctuation: A Preliminary Study on Pleistocene Reef in Bulukumba, South Sulawesi Imran, A. M.; Farida, M.; Arifin, M. F.; Husain, R.; Hafidz, A.
Indonesian Journal on Geoscience Vol 3, No 1 (2016)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.3.1.53-66

Abstract

DOI:10.17014/ijog.3.1.53-66Pleistocene reefs in eastern part of Indonesia are abundantly found along the coast as raised reef. They express highly tectonized and/or uplifted area characterized by several terraces. Therefore the reef size is narrow. This research is located at Bira District of Bulukumba Regency or it lies at the southern tip of South Sulawesi Peninsula. The objective of this research is to define depositional environment based on coral development. Several methods were applied such as intersect lines which were perpendicular to the cliff, geochemical and petrographic analyses, as well as paleoenvironment interpretation. Three facies are described at the Pleistocene reef, namely 1) Reef Front Facies, 2) Reef Core Facies, 3) Back Reef Facies. Based on facies association and organism accumulation, the depositional environment of Pleistocene reef is interpreted to be developed in a small reef complex on an unstable basement. The reef has experienced at least 3 (three) times of sea level fluctuation.
Diagnostic Genesis Features of Au-Ag Selenide-Telluride Mineralization of Western Java Deposits Yuningsih, Euis Tintin; Matsueda, Hiroharu; Rosana, Mega F.
Indonesian Journal on Geoscience Vol 3, No 1 (2016)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.3.1.67-76

Abstract

DOI: 10.17014/ijog.3.1.67-76The ore mineralogy of the westernmost part of West Java such as Pongkor, Cibaliung, Cikidang, Cikotok, and Cirotan are characterized by the dominance of silver-arsenic-antimony sulfosalt with silver selenides and rarely tellurides over the argentite, whereas the eastern part of West Java including Arinem and Cineam deposits are dominated by silver-gold tellurides. Mineralogy of Se-type deposits at Pongkor, Cikidang, Cibaliung, Cisungsang, and Cirotan and Te-type deposits at Arinem and Cineam shows their different geochemical characteristics. Mineralogical and geochemical differences can be explained by variation of physico-chemical conditions that existed during gold-silver deposition by applying the phase relation among sulfide, telluride, and selenide mineral association in the deposits. The relative values of ƒSe2(g), ƒTe(g), and ƒS2(g) control the actual presence of selenide or telluride minerals within the West Java deposits, which also depend on their concentrations in the hydrothermal fluid. Even though the concentration of selenium in the hydrothermal fluid of Te-type deposits might have been similar or even higher than that in the Se-type, early substitution of selenium in the sulfide minerals prevents its concentration in the hydrothermal fluid to the levels for precipitating selenide minerals. Therefore, early sulfide mineral deposition from reduction fluids will not increase the ƒSe2(g)/ƒS2(g) ratio to form selenide minerals in Te-type deposits of Arinem and Cineam, other than selenium-bearing sulfide mineral such as Se-bearing galena or Se-bearing pyrargyrite-proustite.
Volcanostratigraphic Sequences of Kebo-Butak Formation at Bayat Geological Field Complex, Central Java Province and Yogyakarta Special Province, Indonesia Mulyaningsih, Sri
Indonesian Journal on Geoscience Vol 3, No 2 (2016)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.3.2.77-94

Abstract

DOI:10.17014/ijog.3.2.77-94Bayat Complex is usually used as a work field for students of geology and other geosciences. The study area is located in the southern part of the Bayat Complex. Administratively, it belongs to Central Java Province and Yogyakarta Special Province. The lithology of Bayat is very complex, composed of various kinds of igneous, sedimentary, metamorphic, and volcanic rocks. Most of previous researchers interpreted Bayat as a melange complex constructed within a subduction zone. Kebo-Butak is one of formations that forms the Bayat field complex. The formation is composed of basalt, layers of pumice, tuff, shale, and carbonaceous tuff. Most of them are known as volcanic rocks. These imply that volcanic activities are more probable to construct the geology of Bayat rather than the subducted melange complex. The geological mapping, supported by geomorphology, petrology, stratigraphy, and geological structures, had been conducted in a comprehensive manner using the deduction-induction method. The research encounters basalt, black pumice, tuff with basaltic glasses fragments, zeolite, argilic clay, as well as feldspathic- and pumice tuff. Petrographically, the basalt is composed of labradorite, olivine, clinopyroxene, and volcanic glass. Black pumice and tuff contain prismatic clinopyroxene, granular olivine, and volcanic glasses. Feldspathic tuff and pumice tuff are crystal vitric tuff due to more abundant feldspar, quartz, and amphibole than volcanic glass. Zeolite comprises chlorite and altered glasses as deep sea altered volcanic rocks. The geologic structure is very complex, the major structures are normal faults with pyrite in it. There were two deep submarine paleovolcanoes namely Tegalrejo and Baturagung. The first paleovolcano erupted effusively producing basaltic sequence, while the second one erupted explosively ejecting feldspathic-rich pyroclastic material. The two paleovolcanoes erupted simultaneously and repeatedly.
Surface Rupture and Geotechnical Features of The July 2, 2013 Tanah Gayo Earthquake Daryono, Mudrik Rahmawan; Tohari, Adrin
Indonesian Journal on Geoscience Vol 3, No 2 (2016)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.3.2.95-105

Abstract

DOI:10.17014/ijog.3.2.95-105An assessment of surface rupture and collateral ground failures can help to evaluate the impact of future earthquakes. This paper presents the results of a field survey conducted to map the surface rupture and geotechnical phenomena associated with the ground shaking during the July 2, 2013 earthquakes in Tanah Gayo Highland. The objectives of this survey are to document and to characterize the surface ruptures as well as to identify types of earthquake-induced ground failures. Results of the survey identified four best sites of possible surface rupture. Two locations are obvious surface ruptures that can be traced on primary topographic feature of the active fault segment from the north to the south, crossing Pantan Terong Hill. The fault segment has a total mapped length of 19 km, with WNW trending zone and a dextral rupture offset. The ground shaking also resulted in landslides and liquefaction in areas underlain by very fine-grained tuffaceous sands. Based on the field survey, it can be concluded that the newly defined active fault segment, the Pantan Terong segment, is likely the segment that ruptured at the July 2, 2013 Tanah Gayo earthquake. Due to the soil types and unstable rocky slopes in the hilly Central Aceh region, large-scale landslides are primary risks during an earthquake event in this region.
Petrogenesis of Rinjani Post-1257-Caldera-Forming-Eruption Lava Flows Rachmat, Heryadi; Rosana, Mega Fatimah; Wirakusumah, Ade Djumarma; Jabbar, Gamma Abdul
Indonesian Journal on Geoscience Vol 3, No 2 (2016)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.3.2.107-126

Abstract

DOI:10.17014/ijog.3.2.107-126After the catastrophic 1257 caldera-forming eruption, a new chapter of Old Rinjani volcanic activity beganwith the appearance of Rombongan and Barujari Volcanoes within the caldera. However, no published petrogeneticstudy focuses mainly on these products. The Rombongan eruption in 1944 and Barujari eruptions in pre-1944, 1966,1994, 2004, and 2009 produced basaltic andesite pyroclastic materials and lava flows. A total of thirty-one sampleswere analyzed, including six samples for each period of eruption except from 2004 (only one sample). The sampleswere used for petrography, whole-rock geochemistry, and trace and rare earth element analyses. The Rombonganand Barujari lavas are composed of calc-alkaline and high K calc-alkaline porphyritic basaltic andesite. The magmashows narrow variation of SiO2 content that implies small changes during its generation. The magma that formedRombongan and Barujari lavas is island-arc alkaline basalt. Generally, data show that the rocks are enriched in LargeIon Lithophile Elements (LILE: K, Rb, Ba, Sr, and Ba) and depleted in High Field Strength Elements (HFSE: Y, Ti,and Nb) which are typically a suite from a subduction zone. The pattern shows a medium enrichment in Light REEand relatively depleted in Heavy REE. The processes are dominantly controlled by fractional crystallization andmagma mixing. All of the Barujari and Rombongan lavas would have been produced by the same source of magmawith little variation in composition caused by host rock filter process. New flux of magma would likely have occurredfrom pre-1944 until 2009 period that indicates slightly decrease and increase of SiO2 content. The Rombongan andBarujari lava generations show an arc magma differentiation trend.
Seismic Interpretation of the Nam Con Son Basin and its Implication for the Tectonic Evolution Tuan, Nguyen Quang; Tri, Tran Van
Indonesian Journal on Geoscience Vol 3, No 2 (2016)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.3.2.127-137

Abstract

DOI:10.17014/ijog.3.2.127-137The Nam Con Son Basin covering an area of circa 110,000 km2 is characterized by complex tectonic settings of the basin which has not fully been understood. Multiple faults allowed favourable migration passageways for hydrocarbons to go in and out of traps. Despite a large amount of newly acquired seismic and well data there is no significant update on the tectonic evolution and history of the basin development. In this study, the vast amount of seismic and well data were integrated and reinterpreted to define the key structural events in the Nam Con Son Basin. The results show that the basin has undergone two extentional phases. The first N - S extensional phase terminated at around 30 M.a. forming E - W trending grabens which are complicated by multiple half grabens filled by Lower Oligocene sediments. These grabens were reactivated during the second NW - SE extension (Middle Miocene), that resulted from the progressive propagation of NE-SW listric fault from the middle part of the grabens to the margins, and the large scale building up of roll-over structure. Further to the SW, the faults of the second extentional phase turn to NNE-SSW and ultimately N - S in the SW edge of the basin. Most of the fault systems were inactive by Upper Miocene except for the N - S fault system which is still active until recent time.
An Overview on the Possibility of Scandium and REE Occurrence in Sulawesi, Indonesia Maulana, Adi; Sanematsu, Kenzo; Sakakibara, Masayuki
Indonesian Journal on Geoscience Vol 3, No 2 (2016)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.3.2.139-147

Abstract

DOI:10.17014/ijog.3.2.139-147The development in modern-high technology application is growing rapidly, resulting in the constant supply of critical metal and rare earth elements (REE). Currently, resources of these elements are restricted and new source of these elements need to be discovered accordingly. Scandium (Sc) as one of critical metals is an important metal for electrolyte of solid oxide fuel cells and other advance technology. In addition, REE are the important elements in the use of permanent magnets and rechargeable batteries. This manuscript reports an overview on the possibility of scandium and rare earth element occurrences in Sulawesi. Sc is concentrated in limonite layers in Soroako ultramafic rocks as a result of Fe3+ site substitution of mafic minerals (pyroxene, amphibole, etc.) during a laterization process. REE are enriched in association with clay minerals in B horizon from heavily weathered granitic rocks in Palu and Masamba, suggesting the possibility of ion-adsorption style mineralization. The lateritic soil of the ultramafic rocks and the weathered crusts of the granitic rocks in Sulawesi could be the potential sources of scandium and rare earth elements, respectively.
REE Comparison Between Muncung Granite Samples and their Weathering Products, Lingga Regency, Riau Islands Irzon, Ronaldo; Syafri, Ildrem; Hutabarat, Johannes; Sendjaja, Purnama
Indonesian Journal on Geoscience Vol 3, No 3 (2016)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.3.3.149-161

Abstract

DOI:10.17014/ijog.3.3.149-161The increasing demand for Rare Earth Elements (REE) is related to the continous development of technology, and these elements are used in modern equipments. REE can occur in igneous and sedimentary rocks in significant amounts as primary deposits, whereas the secondary REE deposit can be produced by intensive lateritic weathering of bedrocks under the tropical or subtropical climate. Lateritic process can increase REE concentration from sub-economic levels in host rocks to be more valuable. Muncung Granite is located in a tropical area of Lingga Regency, Riau Islands Province. REE occurs in the Muncung Granite and in weathered layers (saprolite, laterite, and soil). ICP-MS was applied to measure the REE content in all samples of this study. The average REE content of the Muncung Granite is 265 ppm with Eu anomaly in REE’s spider diagrams. Lateritization process has increased REE content by more than four times compared to that in the Muncung Granite. Ce and Eu anomalies in weathered layers can be associated with weathering process and initial REE contents in the host rock. Ce anomaly in a laterite layer is found to have a negative correlation to REE total enrichment. The REE level in the Muncung Granite is higher than the content in the soil and saprolite layers, but lower than that in the laterite.

Page 21 of 33 | Total Record : 323

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