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INDONESIA
Indonesian Journal on Geoscience
ISSN : 23559314     EISSN : 23559306     DOI : -
Core Subject : Science,
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.
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Articles 5 Documents
Search results for , issue " Vol 2, No 2 (2015)" : 5 Documents clear
Magma Chamber Model of Batur Caldera, Bali, Indonesia: Compositional Variation of Two Facies, Large-Volume Dacitic Ignimbrites Sutawidjaja, Igan S.; Rosana, Mega F.; Watanabe, K.
Indonesian Journal on Geoscience Vol 2, No 2 (2015)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.2.2.111-124

Abstract

DOI:10.17014/ijog.2.2.111-124Batur is one of the finest known calderas on Earth, and is the source of at least two major ignimbrite eruptions with a combined volume of some 84 km3 and 19 km3. These ignimbrites have a similar compositions, raising the question of whether they are geneticaly related. The Batur Ignimbrite-1 (BI-1) is crystal poor, containing rhyodacitic (68 - 70wt % SiO2), white to grey pumices and partly welded and unwelded. The overlying Batur Ignimbrite-2 (BI-2) is a homogeneous grey to black dacitic pumices (64 - 66 wt % SiO2), unwelded and densely welded (40 - 60% vesicularity), crystal and lithic rich. Phase equilibria indicate that the Batur magma equilibrated at temperatures of 1100 - 1300oC with melt water contents of 3 - 6 wt%. The post-eruptive Batur magma was cooler (<1100oC) and it is melt more water rich (> 6 wt % H2O). A pressure of 20 kbar is infered from mineral barometry for the Batur magma chamber. Magmatic chamber model is one in which crystals and melt separate from a convecting Batur magma by density differences, resulting in a stratified magma chamber with a homogeneous central zone, a crystal-rich accumulation zone near the walls or base, and a buoyant, melt-rich zone near the top. This is consistent with the estimated magma temperatures and densities: the pre-eruptive BI-1 magma was hoter (1300oC) and more volatile rich (6 wt % H2O) with density 2.25 g/cm3 than the BI-2 magma (1200oC; 4 wt % H2O) in density was higher (2.50 g/cm3). Batur melt characteristics and intensive parameters are consistent with a volatile oversaturation-driven eruption. However, the higher H2O content, high viscosity and low crystal content of the BI-1 magma imply an external eruption trigger.
Seismic and Sequence Analysis of Middle to Late Miocene Deposits of Northeast Java Basin Yuniardi, Yuyun
Indonesian Journal on Geoscience Vol 2, No 2 (2015)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.2.2.101-110

Abstract

DOI:10.17014/ijog.2.2.101-110This study is focused on Middle to Late Miocene sediments. As depicted in the regional geology of Indonesia, the area of study is part of Northeast Java Basin. There are three phases of tectonism in the basin: extensional tectonics at Eocene-Oligocene time, compressional tectonics at Middle Miocene, and compressional tectonics at Miocene-Pliocene time. The result of the study shows three sequences were developing during Middle to Late Miocene, those are: (1) Middle Miocene sequence-1 (MM-1 sequence) consisting of a Lowstand Tract System deposition in Middle Miocene-1 (LST MM-1), Transgressive System Tract deposition in Middle Miocene-1 (TST MM-1), and Highstand System Tract deposition in Middle Miocene-1 (HST MT-2); (2) Middle Miocene sequence-2 (MT-2 sequence), comprising Transgressive System Tract Middle Miocene-1 (TST MM-2), and Highstand System Tract deposition in Middle Miocene-1 (HST MM-2); (3) Late Miocene sequence-1 (LM-1 sequence), composed of a Lowstand Tract System deposition in Late Miocene -1 (LST LM-1) and a Transgressive System Tract deposition in Late Miocene-1 (TST LM-1).
Geothermal System as the Cause of the 1979 Landslide Tsunami in Lembata Island, Indonesia Yudhicara, Yudhicara; Bani, Phillipson; Darmawan, Alwin
Indonesian Journal on Geoscience Vol 2, No 2 (2015)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.2.2.91-99

Abstract

DOI:10.17014/ijog.2.2.91-99A tsunami landslide which caused hundreds casualties and lots of damage took place on Lembata Island in 1979. In order to understand the characteristics of the landslide mechanism, a field survey was conducted in 2013 which sampled both the origin soil and landslide material, and the water from hotspring around the landslide site. The physical properties of the soil obtained show that the original soil has dominantly coarser grain than the landslide material (80.5% coarser grain compared to 11.8% coarse grain respectively) which indicates that the soil has become finer and softer. Hot spring analysis indicated that the mineral content of the water was 99.48% SO4. This shows that magmatism processes are involved which caused the soil to become acidic and may have fragilised the system. Results of X-ray Diffraction Mineralogy Analysis (XRD) show that the original soil is composed of minerals of cristobalite, quartz, and albite, while the landslide material consists of clay minerals such as quartz, saponite, chabazite, silicon oxide, and coesite which are typical minerals in a hydrothermal environment. Based on these results, it can be concluded that the area was influenced by an active geothermal system that could be the main source mechanism behind this disastrous event. 
The Lithofacies Association of Brown Shales In Kiliran Jao Subbasin, West Sumatra Indonesia Sunardi, Edy
Indonesian Journal on Geoscience Vol 2, No 2 (2015)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.2.2.77-90

Abstract

DOI:10.17014/ijog.2.2.77-90The lithofacies association, mainly lithology and depositional sequences of the Brown Shale Unit of Pematang Group was studied based on recent fieldwork at Karbindo Coal Mine, in Kiliran Jao Subbasin,West Sumatra, Indonesia. The lower part of the Brown Shale Unit consists of coal and limestone facies which were deposited in a marginal lacustrine area. The limestone was generated by evaporatic processes characterized by the presence of primary calcite crystals. The upper part of the unit, from bottom to top, is composed of six facies associations, among all: amalgamated massive thick bedded shales, interlaminated shales and siltstones, interbedded grey and red shales, fossiliferous shales, massive thick bedded shales, and interlaminated shale and sandstone facies. Those facies were deposited in a shallow to deep water lacustrine environment, characterized by their lithology compositions, sedimentary structures, and fossil contents. The unit has such as high content of reworked organic matters-bearing shales and mudstones. Turbiditic sedimentary structures, gastropods, and bivalves are common.
Developing a Land Suitability Index for Agricultural uses in Dry Lands from Geologic Point of View Using GIS - a Case Study from Jordan Al Farajat, Mohammmad; Mohammad, Alsharifa Hind; Diabat, Abdullah; Al Ibraheem, Hassan
Indonesian Journal on Geoscience Vol 2, No 2 (2015)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.2.2.63-76

Abstract

DOI:10.17014/ijog.2.2.63-76In the context of the study, a Multi-criteria evaluation (MCE) in GIS was used in developing suitability index to optimize suitable lands for agricultural uses and seasonal farming in dry lands from geologic point of view. This study was performed in the areas between Mafraq and Zarqa Cities in Jordan which are classified as arid lands. The study aims at protecting groundwater from pollution, reducing soil salting, reducing irrigation water loss caused by evaporation, and increasing crop productivity. The geo-environmental parameters of the named area including geology, groundwater depths, soil depths and textures, climatic conditions, topographic settings, and groundwater vulnerability conditions were mapped and converted into layers with special rates, given weights, and then modeled using the multi criteria evaluation (MCE) option, using Decision Making Modeling in IDRISI (GIS software) to reach at the best choice of lands for agricultural activities, and also to determine which of these lands are suitable for summer farming and which are suitable for winter farming.

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