Garuda - Garba Rujukan Digital

Article Per Year (5 Year)

All

IJOG : Indonesian Journal on Geoscience

IJOG
Website

Published by Geological Agency of Indonesia

ISSN : 23559314 EISSN : 23559306 DOI : -

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.

Arjuna Subject : -

Articles 796 Documents

50 51 52 53 54

The Magnetostratigraphy and the Age of So’a Basin Fossil-Bearing Sequence, Flores, Indonesia Dida Yurnaldi; Ruly Setiawan; Emma Yan Patriani
Indonesian Journal on Geoscience Vol 5, No 3 (2018)
Publisher : Geological Agency

DOI: 10.17014/ijog.5.3.221-234Three fossil-bearing intervals have been recognized in the Pleistocene So’a Basin, with the upper one holding important evidence of hominin fossils. The sequence also contains numerous in situ stone artifacts and fossils of other vertebrate taxa. Therefore, multiple dating techniques are crucial to secure the age of the fossil and artifact-bearing layers, especially the one with the hominin remains. This paper deals with the palaeomagnetic dating of the So’a Basin sequence to assist other dating methods that have been applied, and to refine the chronostratigraphy of the area. Palaeomagnetic sampling was conducted in four sections along a west to east transect. Four magnetozones can be recognized, consisting of two reverse and two normal polarity zones. By using the available radiometric ages as a guide and comparing the So’a Basin magnetostratigraphy with the Standard Geomagnetic Polarity Time Scale (GPTS), it became clear that both reverse magnetozones are part of the Matuyama Chron, while the normal magnetozones are the Jaramillo subchron and the Brunhes Chron. These palaeomagnetic dating results support the available radiometric dates and refine the age of the fossil-bearing deposits of the So’a Basin.

Tectonic Control on the Formation of Cleats in the Coal Beds of the Sajau Formation, Berau Basin, Northeast Kalimantan Adjat Sudradjat; Ahmad Helman Hamdani
Indonesian Journal on Geoscience Vol 5, No 3 (2018)
Publisher : Geological Agency

DOI: 10.17014/ijog.5.3.235-250Coal seams of lignite- to subbituminous rank of Pliocene-age from the Sajau Formation of the Berau Basin are characterized by the presence of a natural fracture system, including cleats. Often, these opening-mode fractures consist of two orthogonal sets (face and butt cleats), both almost perpendicular to the bedding. This paper describes the distribution of orientation, spacing, and aperture of cleats formed in the seams of the Sajau Formation. All observations and measurements were conducted at macroscopic, mesoscopic, and microscopic scales. The butt cleat mean orientations are NE-SW and NW-SE, whereas the face cleat mean orientations are NNE-SSW and NE-SE, and the cleat dip is at a high angle of 75° to the north. The angles between the orientations of these cleat sets are nearly 90°; that is, they are orthogonal. The spacing of the macroface cleats is between 9.52 and 14.46 cm (averaging 11.61 cm), while the spacing of the butt cleats is between 2.3 and 11.3 cm (averaging 5.35 cm). The mean aperture is 0.54 mm. In contrast, the mean spacing of the mesoface cleats is 3.09 mm, and the aperture measurements of these cleats range from 0.0478 to 0.0741 mm (averaging 0.0549 mm). The results obtained from outcrops and X-ray CT (computed tomography) scan clearly indicate that the NNE-SSW face cleat orientations are strictly parallel to the elongation of the main tectonic structures in the studied area. Their origin may be explained by their relationship with local tectonic stress (the maximum principal stress, σ1, was horizontal). Partial least square analysis of data collected from cleats and faults in the area indicates that a power law distribution exists between the cleat characteristics (spacing, density, and aperture), and the distance of the faults (R2 = 0.56). Cleat formation in the Sajau Formation was mainly controlled by the mechanical response to tectonic stresses, which generated a unique cleat network in the coal. Based on the SEM photography, it is concluded that the development of microcleats in the Sajau Formation resulted from both endogenic processes and tectonic activities as indicated by the change in the shape of the cleats, from straight line to curved shape and branching (intersection of multiple cleats that form a conical network at the end).

Determination of Hydrocarbon Zones Using Logging Data Analysis in A Sandstone Reservoir (Case Study: Structure ‘TL’ Basin North West Java) Herianto Herianto
Indonesian Journal on Geoscience Vol 5, No 3 (2018)
Publisher : Geological Agency

DOI: 10.17014/ijog.5.3.251-263Northwest Java Basin is one of the Indonesian basins that has the potential of hydrocarbon reservoir. A petrophysical analysis plays a role in determining the physical properties of reservoir rocks such as shale volume, porosity, and water saturation zones which is to analyze the hydrocarbon zone possibilities (net pay). A qualitative analysis and correlation of rock lithology study were carried out at seven wells, while a quantitative study was performed by calculating the volume of the shale with a linear method, density-neutron porosity, and water saturation using simandoux equation, then zoning the prospect zones was finally done. Based on the calculation and data analysis, Vsh cutoff value obtained is 23%, the porosity is 10.6%, and water saturation is 71%. Then, the zones of hydrocarbon prospects were recovered, that are the PI-08 wells (9.632 ft - 9.662 ft), PI-10 (9.420 ft - 9.468 ft, 9.475 ft - 9.516 ft, 10.155 ft - 10.175 ft), well PI-11 (9.268 ft - 9.288 ft), well PI-11ST (9.268 ft - 9.927 ft), well PI-12 (9.396 ft - 9.461 ft, 10.047 ft - 10.059 ft), and PI-13 wells (9.356 ft - 9.416 ft, 9.980 ft - 10.000 ft).

Groundwater Occurrence Prediction using Regressions on Morphometric Variables in Upstream Progo Watershed, Yogyakarta T. Listyani; Budiadi Budiadi
Indonesian Journal on Geoscience Vol 5, No 3 (2018)
Publisher : Geological Agency

DOI: 10.17014/ijog.5.3.265-276Geomorphological mapping has been done at the upstream part of Progo Drainage Area by measuring some geomorphological indexes and level of shallow groundwater level at 196 stations, to investigate connections between geomorphological characteristics and groundwater system in the area. These indexes are valley floor - height ratio (Vf), valley cross section (Vratio o rVr), stream gradient index (SL), and drainage density (Dd). Based on the linear regression analysis, the four indexes show none to very weak correlation to water table at most locations. It means that all width, height, and width of the river valley do not control shallow groundwater level. However, some locations indicate a strong control of elevation to shallow groundwater level. The first case indicates that there is another controlling factor to the shallow groundwater system. Most likely, a deeper aquifer exists at those locations, which does not show up in the second case. All results give a preliminary indication that morphometry can be used to predict groundwater system in the area.

Element Mobilization During Weathering Process of Ultramafic Complex in North Konawe Regency, Southeast Sulawesi Based on A Profile from Asera Ronaldo Irzon; Baharuddin Abdullah
Indonesian Journal on Geoscience Vol 5, No 3 (2018)
Publisher : Geological Agency

DOI: 10.17014/ijog.5.3.277-290The North Konawe Regency, located in the northern part of the southeast arm of Sulawesi Province, is occupied mainly by Ophiolite Complex. Recent studies on weathering of ultramafic complex have been focussed on the composition of laterite in relation to heavy metal explorations. In Asera area, North Konawe, a 3.1 m wide outcrop of ultramafic rocks is related to nickel laterite potential. In this study, an elemental change during the weathering process is discussed, including the mobilization of rare earth elements. XRF and ICP-MS from The Centre for Geological Survey of Indonesia are the two important geochemistry instruments used in this study. Si, Mg, and Ca are depleted during weathering, whilst the enriched elements are Fe, Al, Ti, and some heavy metals such as Cr, Mn, and Co. A different mobilization pattern is detected on Ni, because of its relation to Mg. Cs, Rb, and Ba are concentrated in a clayey horizon of upper laterite. The increase of REE concentrations is parallel to both Fe and Mn which rises to the top of laterite. Ce and Eu negative anomaly trends indicate oxidizing condition through the weathering process, although the studied profile, influenced by allochthon material, morphology condition, and geochemistry composition, indicates that the transported rock fragments were originated from ultramafic rock.

Geochemical Characteristics of Sunda Volcanic Arc in Sumatra and Andaman Hananto Kurnio
Indonesian Journal on Geoscience Vol 6, No 1 (2019)
Publisher : Geological Agency

DOI: 10.17014/ijog.6.1.1-16Geochemical characteristics of Sunda volcanic belt are recognized from each characteristic of Weh Island, Tabuan Island in Semangko Bay, South Sumatra, and Andaman Islands. Trace and rare earth elements (REE) are produced by fumaroles in a marine environment of submarine volcano of Weh Island characterized by barium (Ba) as an indicator of sea water influence in the mineralization process, while sulphide minerals do not occur in this area. REE pattern compared to Mid Oceanic Ridge Basalt (MORB) shows a characteristic of subduction tectonics and is distributed in shallow coastal water of high energy. Based on comparison of REE contents in all samples, it reveals that volcanism process causes REE enrichments either in the past or in recent. Geochemical characteristics of Tabuan Island in Semangko Bay reveal the occurrence of hydrothermal mineralization followed by pervasive occurrences of sulphide minerals in vein-type disseminations enriched in Au, Ag, Zn, Pb, Cu, As, Sb, Ba, and Mn. Geochemical characteristics of Andaman Islands reveal imprint of substantial subduction component in the form of sediment fluid and melt and fluid-induced subduction component derived from altered oceanic crust.

Study of Seawater Intrusion in Deep Aquifers of Semarang Coast Using Natural Isotopes and Hydrochemicals Agus Budi Wijatna; Muhammad Kayis; Satrio Satrio; Evarista Ristin Pujiindiyati
Indonesian Journal on Geoscience Vol 6, No 1 (2019)
Publisher : Geological Agency

DOI: 10.17014/ijog.6.1.17-28Seawater intrusion in deep aquifers of Semarang Coast is important to be investigated, because Semarang is one of big cities in Indonesia. Besides its dense population, the growth of industries also increases rapidly with the increase of withdrawal of groundwater either from shallow or deep aquifers. Over-exploitation of groundwater can cause a decreasing groundwater quality due to seawater intrusion. Through this study, the salinization from seawater into the deep aquifer system can be observed. Groundwater samples were collected from deep aquifers with the depth around 40-120 m, and then the isotope contents of 18O and 2H as well as the hydrochemical were analyzed. The isotope and hydrochemical analysis results show that six of thirteen samples are of freshwater type. They are in S2, S5, S7, S8, S9, and S13 sites. While the others are supposed to be encroached by seawater. The slight encroached groundwater of S1, S6, and S10 had a fraction of seawater in the range of 0.15 to 0.26, whereas the moderate and high ones were of S3, S4, S11, and S12 which had seawater fraction between 0.25 and 0.34. Seemingly, salinization mechanism of groundwater by seawater does not depend on its distance from the shoreline and bore well depth. It is confirmed to the site of S5 and S7 located 680 m and 950 m from the shoreline, respectively, which were predominated as freshwater type. On the contrary, the groundwater of S10, S11, and S12 located at further sites about 5-6 km from shoreline is clearly indicated seawater intrusion.

Fluid-Rock Interaction During Hydrothermal Alteration at Parangtritis Geothermal Area, Yogyakarta, Indonesia D. F. Yudiantoro; I. Permata Haty; D. S. Sayudi; A. Bayu Aji; S. Umiyatun C.; M. Nuky Adrian
Indonesian Journal on Geoscience Vol 6, No 1 (2019)
Publisher : Geological Agency

DOI: 10.17014/ijog.6.1.29-40Parangtritis Volcano is part of the Tertiary magmatic belt in Java, which was tectonically formed by collisions between the Eurasian Continental Plate and Indo-Australian Oceanic Plate. The collisions have taken place since Late Cretaceous and still continue until today. In that period, the magmatic belt in Java Island was formed and produced mineralization and geothermal. The characterization of geothermal in Tertiary volcanoes differs from the geothermal system that is on Quaternary volcano alignment in the middle of Java, such as: Awibengkok, Wayang Windu, Darajat, and Kamojang which have a high temperature. The purpose of this research is to study the mobilization elements due to interaction of hydrothermal fluids with wall rocks in low enthalpy geothermal regions of the Tertiary magmatic arc in Parangtritis. Identification of minerals and chemical element changes is approached by methods of petrographic and scanning electron microscope (SEM) analyses. As for knowing the composition and the origin of hydrothermal fluids, it used analyses of cations, anions, and isotope δ18O and δD of hot water manifestation. The occurrence of geothermal manifestations in Parangtritis, such as hot water and rock alteration, reflects the interaction of hydrothermal fluids with wall rocks which generates an argillic zone with mineral alteration such as quartz, calcite, montmorillonite, and hematite. The presence of alteration mineral montmorillonite replacing pyroxene provides an evidence that there have been interactions between the fluids and rocks. This interaction is as a process of element mobilization. Decrease in elements Si, Ca, Mg, and Fe is accompanied by an increase of Al during the replacement of pyroxene into montmorillonite. The mobility of this element occurs due to acid fluids. However, the hydrothermal fluid composition of the current hot water manifestation is neutral chloride water type composition, and the origin of the fluids is meteoric water (δ18O: -4.20 ‰ and δD: 23.43 ‰).

Late Holocene Pollen Record of Environmental Changes in Karimata Strait, Sunda Shelf Region Eko Yulianto; Woro Sri Sukapti; Kresna Tri Dewi
Indonesian Journal on Geoscience Vol 6, No 1 (2019)
Publisher : Geological Agency

DOI: 10.17014/ijog.6.1.41-55Pollen analysis has been conducted on a 90 cm gravity core taken from the Karimata Strait to reveal pollen facies in marine sediment and Late Holocene environmental changes in the central Sunda Shelf region. The core site is at 32 m water depth and located about 170 km northwest of Bangka Island, Indonesia. Ten samples were collected at 10 cm intervals through the core. The total number of pollen grains counted in the samples varies between very low (<50 grains) to abundant (>200 grains). High frequencies (50 - 70%) of mangrove pollen are found at 90 to 40 cm indicating that pollen facies in offshore marine sediment may be comparable with those in mangrove forest floor sediment. The core site has been in a neritic environment since its early deposition ca. 1,800 yr B.P. (~150 A.D.) when mangroves vastly grew on the tidal flats of the surrounding islands and they persisted to ca. 700 yr B.P. (~1,250 A.D.). In the middle of this period, a catastrophic event speculatively due to the 535 A.D. Krakatau eruption might have responsible for the decrease of mangroves and the disappearance of benthic foraminifers. The deposition of silicious materials (tephra) due to this eruption might have provided an opportunity for benthic foraminifers to increase their population subsequently. From ca. 700 yr B.P. (~1,250 A.D.) mangroves declined, as indicated by lower frequencies of pollen grain in samples from 30 cm deep upward. It occurred simultaneously with the deposition of coarser sediment and the increase of benthic foraminifer abundance. Interplay of anthropogenic activities, strengthening ENSO cycle, and lowering erosion base level might have been responsible for these environmental changes.

Sedimentary Environment of a Modern Carbonate Platform of Karimunjawa Islands, Central Java Tubagus Solihuddin; Dwi Amanda Utami; Hadiwijaya Lesmana Salim; Joko Prihantono
Indonesian Journal on Geoscience Vol 6, No 1 (2019)
Publisher : Geological Agency

DOI: 10.17014/ijog.6.1.57-72Sitting in a biodiversity “hotspot” of the mid-Sunda Shelf region, Karimunjawa Islands have currently been the priority for marine biodiversity conservation. Knowledge of surface sediments on modern carbonate platform is one of essential information to support conservation policies, but such has received little attention from reef researchers. This study describes the sediment characteristics of the selected modern carbonate platforms of Karimunjawa Islands through integrated sediments and satellite data analysis. Textural group of sediments indicates that moderate to poorly sorted gravelly sands are dominant with no grading pattern concerning geomorphological and habitat succession from landward to seaward. Sediment compositions are predominantly bioclastic components, comprising coral and mollusks as the highest and the second highest estimated order of abundance. The reworked grains and rock fragments, although present, are not volumentary abundant. The carbonate sedimentary facies is primarily composed of mud-lean packstone with additional proportion of grainstone and packstone. There are only slight distinct sedimentological characteristics for all benthic habitats as shown by the principal component analysis revealing overlap relationship between sediment parameters and benthic habitats. The study provides the first characterization of sediments which operate on the modern carbonate platform of Karimunjawa Islands along with their controlling factors and specialized nature.

Page 52 of 80 | Total Record : 796

50 51 52 53 54

Filter by Year

2006 2026

Filter By Issues

All Issue Vol. 13 No. 1 (2026) Vol. 12 No. 3 (2025) Vol. 12 No. 2 (2025) Vol. 12 No. 1 (2025) Vol. 11 No. 3 (2024) Vol. 11 No. 2 (2024) Vol. 11 No. 1 (2024) Vol. 10 No. 3 (2023) Vol. 10 No. 2 (2023) Vol 10, No 2 (2023): in-press Vol. 10 No. 1 (2023) Vol 10, No 1 (2023) Vol. 9 No. 3 (2022) Vol 9, No 3 (2022) Vol 9, No 2 (2022) Vol. 9 No. 2 (2022) Vol. 9 No. 1 (2022) Vol 9, No 1 (2022) Vol 8, No 3 (2021) Vol. 8 No. 3 (2021) Vol 8, No 2 (2021) Vol. 8 No. 2 (2021) Vol 8, No 1 (2021) Vol. 8 No. 1 (2021) Vol 7, No 3 (2020) Vol 7, No 2 (2020) Vol 7, No 1 (2020) Vol 6, No 3 (2019) Vol 6, No 3 (2019): in-press Vol 6, No 2 (2019) Vol 6, No 2 (2019) Vol 6, No 1 (2019) Vol 6, No 1 (2019) Vol 5, No 3 (2018) Vol 5, No 3 (2018) Vol 5, No 2 (2018) Vol 5, No 2 (2018) Vol 5, No 1 (2018) Vol. 5 No. 1 (2018) Vol 5, No 1 (2018) Vol 4, No 3 (2017) Vol 4, No 3 (2017) Vol 4, No 2 (2017) Vol 4, No 2 (2017) Vol 4, No 1 (2017) Vol 4, No 1 (2017) Vol 3, No 3 (2016) Vol 3, No 3 (2016) Vol 3, No 2 (2016) Vol 3, No 2 (2016) Vol 3, No 1 (2016) Vol 3, No 1 (2016): in-press Vol 2, No 3 (2015) Vol 2, No 3 (2015) Vol 2, No 2 (2015) Vol 2, No 2 (2015) Vol 2, No 1 (2015) Vol 2, No 1 (2015) Vol 1, No 3 (2014) Vol 1, No 3 (2014) Vol 1, No 2 (2014) Vol 1, No 2 (2014) Vol 1, No 1 (2014) Vol 1, No 1 (2014) Vol 8, No 4 (2013) Vol 8, No 4 (2013) Vol 8, No 3 (2013) Vol 8, No 3 (2013) Vol 8, No 2 (2013) Vol 8, No 2 (2013) Vol 8, No 1 (2013) Vol 8, No 1 (2013) Vol 7, No 4 (2012) Vol 7, No 4 (2012) Vol 7, No 3 (2012) Vol 7, No 3 (2012) Vol 7, No 2 (2012) Vol 7, No 2 (2012) Vol 7, No 1 (2012) Vol 7, No 1 (2012) Vol 6, No 4 (2011) Vol 6, No 4 (2011) Vol 6, No 3 (2011) Vol 6, No 3 (2011) Vol 6, No 2 (2011) Vol 6, No 2 (2011) Vol 6, No 1 (2011) Vol 6, No 1 (2011) Vol 5, No 4 (2010) Vol 5, No 4 (2010) Vol 5, No 3 (2010) Vol 5, No 3 (2010) Vol 5, No 2 (2010) Vol 5, No 2 (2010) Vol 5, No 1 (2010) Vol 5, No 1 (2010) Vol 4, No 4 (2009) Vol 4, No 4 (2009) Vol 4, No 3 (2009) Vol 4, No 3 (2009) Vol 4, No 2 (2009) Vol 4, No 2 (2009) Vol 4, No 1 (2009) Vol 4, No 1 (2009) Vol 3, No 4 (2008) Vol 3, No 4 (2008) Vol 3, No 3 (2008) Vol 3, No 3 (2008) Vol 3, No 2 (2008) Vol 3, No 2 (2008) Vol 3, No 1 (2008) Vol 3, No 1 (2008) Vol 2, No 4 (2007) Vol 2, No 4 (2007) Vol 2, No 3 (2007) Vol 2, No 3 (2007) Vol 2, No 2 (2007) Vol 2, No 2 (2007) Vol 2, No 1 (2007) Vol 2, No 1 (2007) Vol 1, No 4 (2006) Vol 1, No 4 (2006) Vol 1, No 3 (2006) Vol 1, No 3 (2006) Vol 1, No 2 (2006) Vol 1, No 2 (2006) Vol 1, No 1 (2006) Vol 1, No 1 (2006) More Issue

Home Page

OAI Link

Editorial Team

Contact

Reviewer

Google Scholar

Contact Name
Ivan Ferdian

Contact Email
ivan.ijgbg@gmail.com

Phone
-

Journal Mail Official
ivan.ijgbg@gmail.com

Editorial Address
-

Location
Kota bandung,

Jawa barat

INDONESIA

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Home Page

OAI Link

Editorial Team

Contact

Reviewer

Google Scholar

Contact Name Ivan Ferdian

Contact Email ivan.ijgbg@gmail.com

Phone -

Journal Mail Official ivan.ijgbg@gmail.com

Editorial Address -

Location Kota bandung, Jawa barat INDONESIA

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Contact Name
Ivan Ferdian

Contact Email
ivan.ijgbg@gmail.com

Phone
-

Journal Mail Official
ivan.ijgbg@gmail.com

Editorial Address
-

Location
Kota bandung,

Jawa barat

INDONESIA