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Indonesian Journal on Geoscience

IJOG
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Published by Institut Teknologi Nasional Yogyakarta

ISSN : 23559314 EISSN : 23559306 DOI : http://ijog.bgl.esdm.go.id/index.php/IJOG/article/

Core Subject : Science, Engineering,

Earth & Planetary Sciences Engineering

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 324 Documents

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Natural Compaction of Semarang-Demak Alluvial Plain and Its Relationship to the Present Land Subsidence Sarah, Dwi; Hutasoit, Lambok M; Delinom, Robert M; Sadisun, Imam A
Indonesian Journal on Geoscience Vol 7, No 3 (2020)
Publisher : Geological Agency

DOI:10.17014/ijog.7.3.273-289Land subsidence is the lowering of ground surface due to natural and/or anthropogenic processes. Land subsidence in the Semarang-Demak plain has been going on for more than thirty years, however the contribution of natural and anthropogenic causes is relatively unknown. The Semarang-Demak plain has only been formed recently, as a result of rapid sedimentation during the Holocene. The basin mainly consists of underconsolidated thick clay, vulnerable to excessive settlement due to its own weight and additional pressures. The rate of natural subsidence is quantified by modelling the delayed dissipation of measured overpressure and the resulting vertical deformation, resulting in natural compaction rate of less than 0.8 cm/year in Semarang City and more than 0.8 cm/year in Demak Regency. The subsidence computed for parts of the Semarang-Demak plain were compared to the measured geodetic rate, and the relative contributions of natural and anthropogenic causes are derived. Modelling results show that natural subsidence is more significant at the eastern part of the plain (Demak region) with compaction rate reaching 0.9 - 2.2 cm/year that counts for 48 - 92% of the total land subsidence.

The Significance of the Banda Sea: Tectonic Deformation Review in Eastern Sulawesi Titu-Eki, Adept; Hall, Robert
Indonesian Journal on Geoscience Vol 7, No 3 (2020)
Publisher : Geological Agency

DOI:10.17014/ijog.7.3.291-303The geology of eastern Sulawesi is widely known for its complexity due to multiple deformation stages.The geology on land has been studied excessively, but little assessment has been made on the offshore geology, thus the geological evolution of the area remains a subject of controversy. A thorough observation of high multibeam bathymetry dataset offshore and SRTM dataset onshore provides an understanding on the geological features relating to the tectonic deformation. Exquisite morphological features include carbonate buildups and gravitational collapse dominating the shelf areas whereas distinct form of ridges and seamount exists in the offshore. Structural features in this area including the major Tolo Thrust and South Sula Fault varied structural lineations on land with several polygonal extensional faulting and accretionary wedge on the west of the North Banda Sea. The existence of these features may indicate that the area was majorly deformed during Neogene, specifically relating to the opening of the Banda Sea due to the subduction rollback of Banda.

Preliminary Study of Rare Earth Element and Yttrium (REY) Content of Coal In Sangatta Coalfield, East Kalimantan, Indonesia Anggara, Ferian; T.B.M. Petrus, Himawan; Patria, Aulia Agus; Bangun, Aya Shika
Indonesian Journal on Geoscience Vol 7, No 3 (2020)
Publisher : Geological Agency

DOI:10.17014/ijog.7.3.305-314Kutai Basin is known as one of the most prolific sedimentary coal basins in Indonesia. Coal-bearing sequence in Kutai Basin is mainly Miocene to Eocene in age in which the coal seams are mostly in Miocene strata. Researchers have found that REY concentration in some coals and coal ashes are equal to or higher than that of the conventional deposit, as such coal deposit has become an important source for REY. Moreover, REY recovery as by-product from coal deposits could alleviate the â€œdirtyâ€ into â€œcleanâ€ coal energy. Referring to this shifted paradigm, a study on REY in Indonesian coal has put interest not only for researchers, but also for all stakeholders in this country. In this particular study, Sangatta coalfield in East Kalimantan was chosen as the area to observe the REY concentration. This area has been set due to its interesting geological setting, especially Pinang Dome that might have coal deposit with enriched REY. For the analyzed samples, drill cores were collected and then observed closely using polished section, inductively coupled plasma atomic emission spectroscopy (ICP-AES), and inductively coupled plasma mass spectrometry (ICP-MS). Based on the collected data, the highest REY concentration in coal deposit is located in the nearest part of the Pinang Dome. The REY content in coal deposit is associated with hydrothermal fluids and sediment source. These data suggest that there is a significant effect on Pinang Dome in the REY content in the coal deposit.

Earthquake Potential Hazard Analysis of Palembang City, Sumatra Island Triyoso, Wahyu; Suwondo, Aris; Naibaho, Zael Yahd Xanggam
Indonesian Journal on Geoscience Vol 8, No 1 (2021)
Publisher : Geological Agency

DOI: 10.17014/ijog.8.1.1-9Most of the destructive earthquakes in Sumatra are dominated by thrust mechanisms that occur due to the process of subduction and some earthquakes with strike-slip fault sources such as the Sumatra fault and northwestern Sumatra. The subduction zones along western Sumatra and Sumatran fault zones are active seismic sources of earthquake events. The seismotectonics of South Sumatra can be affected by earthquakes triggered by these seismic sources. In this study, an estimation and analysis of the potential for earthquake hazard curves were carried out in Palembang City due to the influence of subduction zone sources, strike-slip faults, and intermediate to deep earthquake sources. The algorithm of the seismicity smoothing was applied to estimate the seismicity rate for megathrust sources, active faults, and intermediate to deep earthquake sources. The results of the earthquake hazard potential curve showed that the estimated Peak Ground Acceleration (PGA) in the bedrock of the subduction earthquake sources was greater than the estimated ground shaking due to strike-slip fault sources as well as intermediate to deep earthquake sources. To understand better the potential ground shaking, the evaluation of PGA at the surface was then estimated by including the amplification factor. The amplification factor was calculated using the Horizontal-Vertical Spectral Ratio (HVSR) method. Based on the PGA estimated at the surface of 10% probability exceedance level during 50 years, the Palembang City has a potential shaking of around 35 gal, which is likely to be caused by a megathrust earthquake source.

A Combined Petrographic-Geochemical Provenance and Tectonic Setting Study of Palaeozoic Rocks, in East Johor Basin, Peninsular Malaysia Surjono, Sugeng Sapto; Leman, Mohd. Shafeea; Mohamed, Kamal Roslan; Ali, Che Aziz
Indonesian Journal on Geoscience Vol 8, No 1 (2021)
Publisher : Geological Agency

DOI: 10.17014/ijog.8.1.11-24Several greywacke sandstones considered as Paleozoic rocks are found in three different formations, i.e. the Dohol, Linggiu, and Tanjung Leman Formations within the Palaeozoic East Johor Basin. The compositions of twenty-nine sandstone samples were identified using petrographical and geochemical methods to determine the provenance of sandstones as well as the tectonic setting of pre-and syn-sedimentation. Seven samples of them were examined using point counting method to obtain the mineralogical compositions. This petrographical point counting was done by plotting composition percentages to QFL and QmFLt triangular diagrams, The results showed a magmatic arc for Dohol Formation, a change from a magmatic to a recycled orogen for Linggiu Formation, and a recycled orogen for Tanjung Leman Formation. The recycled orogen tectonic setting of Linggiu and Tanjung Leman may have come from the underlying metamorphic and sedimentary rocks of Mersing and Murau Formations. Meanwhile, twenty-two samples were examined using a geochemical method by utilizing the ratio of K2O/Na2O and SiO2. The samples suggest a tectonic setting from both passive continental margin (PM) and active continental margin (ACM). Based on these findings, it is interpreted that the sedimentary rocks in East Johor were deposited in a subduction-related basin, such as fore-arc, magmatic arc, and back-arc.

Study of Production-Injection Strategies for Sustainable Production in Geothermal Reservoir Two-Phase by Numerical Simulation Pratama, Heru Berian; Saptadji, Nenny Miryani
Indonesian Journal on Geoscience Vol 8, No 1 (2021)
Publisher : Geological Agency

DOI: 10.17014/ijog.8.1.25-38The rapid pressure decline in liquid-dominated geothermal fields is a significant problem affecting the steam supply to the power plant. This study aims to understand the reservoir characteristics changes due to extraction of mass and heat from the reservoir through a numerical reservoir simulation under various strategies production-injection. The development of a liquid-dominated geothermal field model is assessed with various production strategies and injection strategies for the generation of 110 MW and 220 MW using a separated steam cycle. Thirty two production-injection strategies from a full factorial have been successfully carried out. The results show a low decrease for both reservoir pressure and decline rate for the steam cap and brine reservoir's production strategy combined with deep and dispersed injection strategy. From a simulation for 220 MW, the strategy for sustainable production is 25% from the steam cap and 75% from brine reservoir, dispersed, and deep reinjection with 9 make-up wells from the steam cap. The lowest decline rate after the 30th year is 0.5%, with Arps 1.0 exponent harmonic decline curve. The implementation of the production-injection strategy needs to be planned from the beginning of exploration or exploitation so that the strategy can be adjusted to changes in reservoir characteristics without causing problems.

Komatiitic Lamprophyre in West Sulawesi: First Evidence for >1350Â°C and 3.5 - 3.8 GPa Mantle Melts Godang, Shaban; Fadlin, Fadlin; Priadi, Bambang; Idrus, Arifudin; Sukadana, I Gde
Indonesian Journal on Geoscience Vol 8, No 1 (2021)
Publisher : Geological Agency

DOI: 10.17014/ijog.8.1.39-58The presence of lamprophyric lavas of Late Cenozoic in Talaya Volcanic Formation at the boundary between the subregencies of Mamuju and Tabulahan (Western Sulawesi) associated with the mantle enrichment rocks of the Adang Volcanics is the subject of this study. Petrologically, lamprophyre is composed of orthopyroxene (enstatite), clinopyroxene (augite), biotite, leucite, amphibole, magnetite, and autometasomatism of chlorite in grain minerals and groundmass. The lamprophyre is classified into monchiquite shoshonitic lamprophyre, and it has a komatiitic composition with the ratio of MgO/Al2O3 > 0.7906 (in wt %). The komatiitic monchiquite lamprophyre is characterized by high MgO (10.02 - 12.67 %), relatively low alumina (Al2O3= 10.98 - 11.70 %), SiO2= 46.43 - 47.8 %, TiO2 (0.84 - 1.00 %), FeOt (7.75 - 7.88 %), and relatively high content of alkaline (Na2O: 2.20 - 2.59 %; K2O: 1.58 - 2.45 %; Total alkali: 4.00 - 4.89 %, and CaO (9.29 - 10.71 %). The geochemical trace element plots using various diagrams suggests the geotectonic setting of the lamprophyric rock was formed in suprasubduction alkaline continental-arc, and the proposed source of magmatism comes from the suprasubduction activities from the east. The protolith of magma was originated from partial melting of depleted MORB mantle (DMM), composed of pyroxene-peridotite (garnet-lherzolite). The partial melting conditions are suggested to occur at high pressure (3.5 - 3.8 GPa) and the depth of ~120 km with melting temperature of >1350Â°C, and the magma is dominantly controlled by olivine fractional crystallization.

Mineralogical, Geochemical, and Raman Spectral Characteristics of Amphibole Mineral Types in Amphibolite from Southern Sanandaj-Sirjan Metamorphic Belt (Iran) Moeinzadeh, Hesam; Rahimisadegh, Hadiseh; Moazzen, Mohsen; Nakashima, Kazu
Indonesian Journal on Geoscience Vol 8, No 1 (2021)
Publisher : Geological Agency

DOI: 10.17014/ijog.8.1.59-72The current study is related to amphiboles in amphibolite rocks in the northwest of Golgohar Iron Mine located in the southern part of Sanandaj-Sirjan metamorphic zone.Petrography observations indicate that the studied rocks are of ortho-amphibolite type, formed from metamorphism of igneous rocks. The analysis of amphibole crystals in amphibolites of the region was done by petrography, electron microprobe, and Raman spectroscopy. Raman spectral pattern of the studied minerals was discussed in comparison to mineral type and chemistry characteristics. Based on mineral chemistry studies, it was discovered that all amphiboles in the studied rocks are calcic with (Ca+Na)Bâ‰¥1.34 and SiIV between 6.27 and 6.76 atoms per formula unit. Based on their enrichment in the elements Al and Fe3+, their composition varies from tschermakite to magnesio-hornblende. Raman spectral peak pattern for amphiboles and terrestrial tremolite does not have significant discriminable differences. However, Raman peak patterns of tremolite have clearly different features versus tschermakite. According to the general formula of amphiboles [A0-1B2C5T8O22(OH, F, Cl)2], the Raman spectrum variability of the tschermakite and tremolite can be due to the position of A site, Al incorporation into M1 + M2 + M3 sites and into the T site.

Insights on Mineralogy and Chemistry of Fairview Gold Mine, Barberton Greenstone Belt, South Africa Altigani, Mohammed Alnagashi Hassan
Indonesian Journal on Geoscience Vol 8, No 1 (2021)
Publisher : Geological Agency

DOI: 10.17014/ijog.8.1.73-99Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and electron microprobe analysis (EMPA) techniques were used to determine the mineralogy and chemistry of dominant sulphide and associated gold deposits at the Fairview Gold Mine of the Barberton Greenstone Belt (BGB). The rocks and ore mineral associations at the Fairview Mine indicate mesothermal (orogenic) conditions for the gold deposit. The whole rock chemistry of the Fairview Mine reflects calc-alkaline affinities, and felsic provenance is revealed by high SiO2, K2O, Al2O3, and TiO2, and low Fe2O3, MgO, Ni, and Cr contents. The mineral assemblages of the Fairview Mine rocks and ores indicate three phases of metamorphisms; regional prograde, thermal, and retrograde metamorphism, which caused zonation and heterogeneity of the ore minerals. The principal ore minerals in this deposit are pyrite, arsenopyrite, pyrrhotite, chalcopyrite, and rare sphalerite, as well as minor gold. The obtained results revealed that sulphides of the Fairview Mine are divided into two types (generations) varying in their morphology, association, and elemental composition. The old type 1 is porous, anhedral, heterogeneous, contains inclusions and rich in As, Ni, Co, and Au compared to type 2. Trace-element distribution and occurrence mode of gold at Fairview mine reflect two phases of gold mineralization. The first stage is associated with sulphides (mainly pyrite and arsenopyrite), whilst the second phase is free-lode hosted by silicates (mainly quartz).

Striations at The Base of The Paleo-Fan and Channel Revealed by 3D Seismic Data, Offshore Cameroon Le, Anh Ngoc
Indonesian Journal on Geoscience Vol 8, No 1 (2021)
Publisher : Geological Agency

DOI: 10.17014/ijog.8.1.101-107The 3D seismic data, offshore Cameroon, reveal the evidence of a Pliocene fan and a channel with a series of striations at their base. The fan and channel developing in Early Pliocene, were characterized by high amplitude reflections with bi-directional downlap on the base of the Pliocene sequence, and interpreted to be deep-water sandrich fan and channel. Pliocene channel flowed from east to west in the High Gradient Slope (HGS), whereas, the fan extended from NE to SW on the Low Gradient Slope (LGS). Individual striations have been imaged that are 20 - 50 m wide, c. 10 - 20 km long, and 4 - 8 m deep, trending NE - SW and E - W, slightly divergent patterns toward downslope. Striations are observed at the base of fan and channel suggesting the beginning of a period of unstable slope creating NE - SW slides in LGS and erosion in HGS. They were followed by the deposition of large scale fan deposits on the LGS and a series of parallel aggradational channels in the HGS. The striated unconformity at the base of the Pliocene sequence may be the result of a major tectonic uplift event or significant climate changes.

Page 30 of 33 | Total Record : 324

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bernadeta subandini astuti

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Home Page

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Contact Name bernadeta subandini astuti

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Editorial Address Jl. Diponegoro No. 57 Bandung, Indonesia

Location Kab. sleman, Daerah istimewa yogyakarta INDONESIA

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Contact Name
bernadeta subandini astuti

Contact Email
bernadeta.palguno@gmail.com

Phone
+6222-7213793

Journal Mail Official
ijog@bgl.esdm.go.id

Editorial Address
Jl. Diponegoro No. 57 Bandung, Indonesia

Location
Kab. sleman,

Daerah istimewa yogyakarta

INDONESIA