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INDONESIA
IJOG : Indonesian Journal on Geoscience
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
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The Application of Parametric and Nonparametric Regression to Predict The Missing Well Log Data Mordekhai Mordekhai; Izzul Qudsi; John Papilon Steven Guntoro
Indonesian Journal on Geoscience Vol. 8 No. 3 (2021)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.8.3.385-399

Abstract

DOI:10.17014/ijog.8.3.385-399Incomplete well log data are very commonly encountered problems in petroleum exploration activity. The development of artificial intelligence technology offers a new possible way to predict the required logs using limited information available. Optimizing conventional statistical theory, machine learning is proven to be a reliable tool for any prediction task in many fields of study. Regression is one of the basic methods that has rapid development and evolved many techniques with different approaches and purposes. In this study, parametric and nonparametric regressions {linear regression, Support Vector Machine (SVM), and Gaussian Process Regression (GPR)} are compared to predict the missing log using the available nearby data. Feature selection was done by performing Principal Component Analysis (PCA) on predictor variables. Different profile of PCA is observed between Cibulakan and Parigi Formations, which is the basis of conducting separate models based on the formation. Among all the selected methods, GPR is consistently making slightly better results. The correlation between the predicted and actual porosity of GPR is observed to be up to 0.19 higher compared to the other methods. Similar observation is also found on the Root Mean Squared Error (RMSE) value comparison. In practice, the GPR method has an inherent advantage compared to other methods, as it provides uncertainty to the prediction based on the standard deviation of each estimation result. The standard deviation of the GPR prediction ranges from 0.006 in high confidence cases and up to 0.077 where uncertainty is high. The models are considered robust and stable according to the RMSE evaluation from cross validation which is consistently giving the value below 0.04. In conclusion, the reliability of regression techniques for predicting the missing well log is exposed in this study, which results demonstrate steady and good accuracy in every formation which are tested on any well logs.
REE-Bearing Minerals in Tin Waste Dumps of Singkep Island: Geochemical Identification and Recovery Ronaldo Irzon
Indonesian Journal on Geoscience Vol. 9 No. 1 (2022)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.9.1.15-26

Abstract

DOI:10.17014/ijog.9.1.15-26Instead of environmental hazard, tailing might contain resources which could be reworked with the development of mining and separation technologies. Tailing dumps and waste ponds which associated with the long period of tin mining are easily found in Singkep Island. The waste should be processed to recover and purify precious metals within, and to reduce environmental degradation. REE-bearing minerals identification in tin tailing based on trace and rare earth element abundances is the aim of this study. Concise mineral beneficiation is illustrated for any further re-work strategy. The tailings collected from four locations in Singkep were analyzed for their trace and rare earth element compositions using ICP-MS at The Centre for Geological Survey. REE content in concentrates was upgraded at the range of 9 to 94 folds of the corresponding wastes. Monazite-(Ce), xenotime, and zircon are the REE-bearing minerals of the studied samples according to the elemental composition. Gravity, flotation, magnetic, and electrostatic methods would be applicable to separate the REE-bearing minerals from the tailing.
Werner Deconvolution Technique for the Interpretation of Residual Aeromagnetic Anomalies of Igbeti Schist Belt; Implication for Marble Exploration Saminu Olatunji; Warith Adewale Adebisi
Indonesian Journal on Geoscience Vol. 9 No. 2 (2022)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.9.2.209-217

Abstract

DOI:10.17014/ijog.9.2.209-217Determination of the straight down range of geologic formation between geographic latitude 8.30 0N to 9 0N and longitude 3.30 0E to 4.30 0E of the Igbeti schist belt became a thing of interest due to the on-going exploration in the region. Aeromagnetic field intensity anomaly data of the bound were then acquired, separated off regional field and a corresponding residual map obtained was later used applying Werner deconvolution method filtering tool. Three magnetic profiles were selected and labelled for the interpretation on the residual anomalies. The result shows that the depth to magnetic source has a maximum value of 1,000 m toward the subsurface in all the profiles selected, indicating the shallow nature of the magnetic source in the area. Based on the structural index shown, it further reveals solutions for contact and dyke which indicates that there are boundaries which separate rocks from one another and the presence of dyke formation. The implication of identical signature from all profiles is that the marble deposit is relative uniform extending to a great depth in the area.
Model Framework for Analysis and Visualization of Climate Disaster Patterns Dian Pratiwi
Indonesian Journal on Geoscience Vol. 9 No. 3 (2022)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.9.3.329-336

Abstract

DOI:10.17014/ijog.9.3.329-336Extreme climate change has almost begun to show symptoms just about in all countries, including Indonesia. At the beginning of 2020, some parts of Indonesia were flooded due to high rainfall intensity. In fact, in DKI Jakarta area the potential for flooding often arrive early. For this reason, an appropriate disaster pattern analysis system needs to be developed and implemented to prevent the incident from recurring by planning better handling. The model framework that was built to create a visualization system for disaster patterns in this study consisted of five stages, namely the image processing stage in the map image, the placement of the coordinates of the affected area, interpolation with the B-Spline method, extrapolation with the Von-Neumann law, and the accurate evaluation of the formed disaster pattern mapping. Through this model framework, it is expected to produce a system design for informative disaster pattern mapping.
Aliphatic Biomarker Signatures of Crude Oil from Tarakan Subbasin, Tarakan Basin, North Kalimantan, Indonesia Yulfi Zetra; R.Y. Perry Burhan; Maulida Fitriyyah; Zjahra Vianita Nugrahaeni
Indonesian Journal on Geoscience Vol. 10 No. 2 (2023)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.10.2.139-150

Abstract

Organic geochemical studies of crude oil from Pamusian Field, Tarakan Subbasin, Tarakan Basin, North Kalimantan, have been done. Biomarker aliphatic hydrocarbon fractions were identified using a combined gas chromatography-mass spectrometer (GC - MS). Identified biomarkers consist of n-alkane groups, isoprenoids, bicyclic sesquiterpenoids, and pentacyclic triterpenoids. The most abundant aliphatic hydrocarbon biomarker is pristane followed by n-C19. The existence of n-alkanes shows a homologous (n-C16- n-C30) with a unimodal distribution type. The abundance of n-C19 is higher than other n-alkanes, supported by LHCPI value of 2.03, as an indicator of organic matter derived from microbial organisms. The amount of long chain n-alkanes (n-C25- n-C30) is almost the same as medium chain n-alkanes (n-C19 - n-C24) indicating the source of organic compounds is not only from microbial organisms, but also from terrestrial higher plants. The presence of 8β (H)-drimane compounds together with homodrimane shows the presence of bacterial input on the formation of oil from organic compounds. Ratio of Pr/Ph is 3.76, ratio of drimane/homodrimane is 1.058, ratio of Pr/n-C17 is 34.41, and ratio of Ph/n-C18 is 16.02 indicating the source of organic compounds came from terrestrial higher plants deposited in the oxic environment, and disposed to increase biodegradation. The CPI value is 0.95, and the highest amount of 17α (H), 21β (H)-hopane compounds suggest that Tarakan Subbasin oil was mature, and the source of organic compounds was derived from bacteria Keywords: Tarakan Basin, organic geochemistry, aliphatic hydrocarbon fraction, CPI
Documentation, Analysis and Reconstruction of the Paleo-landuse of Wadi Musa with Special Reference to the Nabataean Period: A Geomatic Study based on Archaeological Evidence Mohammmad Al Farajat; Saad Twaissi; Mahmoud B Al Hasanat; Abdulla Al-Rawabdeh; Hani Al Falahat; Emad Hijazeen; Ekhlas Al Eide
Indonesian Journal on Geoscience Vol. 8 No. 3 (2021)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.8.3.427-441

Abstract

DOI:10.17014/ijog.8.3.427-441Archaeologists and historians throughout time have relied mainly on textual, architectural, and art-historical analyses to understand the historical context of civilizations. This traditional approach has been challenged, however, by the current new practices in archaeological studies, which tend to rely on more scientific methods (e.g. information systems) to understand the wider context of the socio-cultural aspects of past societies. For example, the Nabataean studies, which for more than seventeen decades after the rediscovery of Petra in 1812, are based on the art historical analysis of the rock-cut facades of the the city of Petra. The wider story of the socio-cultural, political, and economic aspects of the Nabataean culture is still not well understood. Just recently archaeological research was undertaken to improve the understanding of the Nabaatean phenomenon from outside Petra. This paper discusses this new attempt to investigate the spatial organization and land use of Wadi Musa during the Nabataean period based on GIS analysis and new archaeological discoveries. Utilizing GIS in discovering historical phenomena provides a new perspective for analysis, whereby structures are treated not as individual archaeological items but rather as a system. This paper also presents a case study that demonstrates the significance of using GIS for historical research by shedding light on the temporal variation of Wadi Musa settlements with special focus on the paleo-landuse of the Nabatean period. The resulting reconstructed map indicates that Wadi Musa was well planned with special zones for elite residents, industry, rural communities, and agriculture. Social segregation/stratification is also well indicated in the plan of the city. The reconstructed map indicates that the strategy for Nabataean land use for Wadi Musa was to use it as a green zone around the city of Gaia.
Geology, Vein Textures, and Fluid Inclusions of the Cibeber Low-Intermediate Sulfidation Epithermal Au-Ag Orefield, Western Java Cendi D. P. Dana; Arifudin Idrus; Iwan Setiawan; Esti Handayani; Feddy Yurniadi; Ignas A. Meak; Chun-Kit Lai
Indonesian Journal on Geoscience Vol. 8 No. 2 (2021)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.8.2.157-175

Abstract

DOI:10.17014/ijog.8.2.157-175This paper describes the results of surficial geological and alteration mapping combined with several laboratory analyses, including petrography, ore microscopy, ore geochemistry, and fluid inclusion studies, aimed at establishing the nature of mineralization and alteration in the Cibeber area, West Java, Indonesia, and developing a genetic model. The area forms part of the Bayah Dome Complex, which hosts several gold-silver deposits. It is underlain by andesitic lava, tuff breccia, and subordinate sandstone. Its structural framework consists of joints, normal faults, NE-SW dextral strike slip faults, and NW-SE strike-slip faults. Hydrothermal alteration can be divided into four types, viz. silicification, clay-silica, argillic, and propylitic. Mineralization is mostly hosted in quartz veins showing a variety of textures, including massive, colloform-crustiform, breccia, lattice bladed, comb, and saccharoidal. Ore minerals consist of native gold and silver, pyrite, chalcopyrite, sphalerite, galena, tennantite-tetrahedrite, covellite, malachite, hematite, and goethite, while the gangue minerals quartz, illite, epidote, and calcite. Four stages of mineralization/veining are recognized: early, middle (the main ore forming stage), late, and supergene. The highest obtained metal grades are 8.17 ppm Au, 113.6 ppm Ag, 1.23% Cu, 1.28% Pb, and 1.2% Zn. Fluid inclusions from mineralized veins yielded temperatures of 222 - 280°C and salinities of 0.36 - 1.31 wt.% NaCl eq. The hydrothermal fluids are interpreted to have been largely of meteoric origin with the mineralization having formed at a depth of about 258 - 270 m below paleosurface. Both low-sulphidation and intermediate-sulphidation styles of mineralization are present.
A Combination of Embedded Markov Chain and Binomial Probability As A Tool in Sedimentary Facies Analysis Djadjang Jedi Setiadi; Iyan Haryanto; Budi Muljana; Syaiful Alam
Indonesian Journal on Geoscience Vol. 9 No. 3 (2022)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.9.3.291-302

Abstract

DOI:10.17014/ijog.9.3.291-302The methodology of facies analysis may include statistical examination to establish a local facies model. Without such examination, it is very difficult to predict the facies succession and to interpret the changes in depositional conditions from thick or complex stratigraphic sections. Based on the survey of sedimentary geologic literature in Indonesia, it is suggested that the aforementioned statistical method has relatively seldom been used in Indonesia. Such a situation may reflect a gap in information on the methodology and, accordingly, it seems imperative that there should be a re-exposition of the method. This paper presents a concise exposition of the combination of the embedded Markov Chain and binomial probability as one of the most successful statistical methods which are used in facies analysis. The results of previous studies of The Citalang Formation are used as a case study to illustrate its applications to the real geologic world.
Robustness of DRASTIC Method for Groundwater Vulnerability Case of Wadi Nil Aquifer in Jijel, NE Algeria Souhil Mahdid; Nabil Chabour; Taha-Hocine Debieche; Abdelmalek Drouiche; Séverin Pistre
Indonesian Journal on Geoscience Vol. 9 No. 2 (2022)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.9.2.229-246

Abstract

DOI:10.17014/ijog.9.2.229-246The alluvial water table of Wadi Nil is characterized by an abundance of groundwater, attributed to the high rainfall (1,000 mm/yr on average) of the region, the good permeability of its aquifer (10-3 to 10-4 m/s), and its significant thickness (35 to 100 m). Its waters are used for drinking water as well as for irrigation. In recent years (2000-2020), significant growth in terms of urban, agricultural, and industrial activities has developed on the plain, and has generated a significant amount of waste and effluents. In order to protect the groundwater resource, a map of the vulnerability of the water table to pollution, intended to guide public policies, has been drawn up. The DRASTIC method is a method chosen for the creation of this map, in view of its efficiency and reliability. The results obtained show that the groundwater consists of three zones: the first zone - of moderate vulnerability - is located in the outcrop areas of the marl formations (central part of the plain); the second - of high vulnerability - occupies most of the plain, composed mainly of the wadi alluvial formations; and finally the third - of very high vulnerability - is located in the downstream part of the groundwater, where the aquifer formations are sandy. The statistical analyses and sensitivity analysis of DRASTIC parameters highlight the importance of the parameters «water depth, recharge, and impact of the vadose zone» in the elaboration of the vulnerability map of the studied area, and show that the approach is relatively robust. Nevertheless, if the “water depth” and “recharge” parameters can be constrained by field measurements, the “impact of vadose zone” parameter appears to be the most delicate, because it is both sensitive and associated with uncertainties
Mass-Transport Deposit In Deep Water Setting, Offshore Cameroon, West Africa Anh Ngoc Le
Indonesian Journal on Geoscience Vol. 8 No. 2 (2021)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.8.2.231-219

Abstract

DOI:10.17014/ijog.8.2.231-219Mass-transport deposits (MTDs) have been analyzed over an area of 1,500 km2 in the deep-water setting of West Africa, focusing on the Early Tertiary sequence using high resolution of 3D seismic data. Observed MTD is about 10 km wide and 20 km long, up to 140 m thick, on the high gradient slope of 3.4o, extending from east to west. Internal seismic facies of the mass consist of extensional imbrication facies in the upslope area, thrusted facies downslope area. The MTD likely was triggered by a combination of mechanisms. Uplift in the Tertiary, dated at about 30 - 40 Ma, corresponding to the unconformity KS_5 may be the main reason that causes slope failure. Besides, possibly releasing gas from the gas hydrate stability zone may contribute to triggering mass-transport deposition in the study area.

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