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IJOG : Indonesian Journal on Geoscience

IJOG
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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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Quaternary Geological Phenomena in Labuhan Area, Pandeglang Regency, Banten Province U. Lumban Batu; S. Poedjoprajitno
Indonesian Journal on Geoscience Vol 7, No 4 (2012)
Publisher : Geological Agency

DOI: 10.17014/ijog.v7i4.148Geological features in Labuhan area were studied from the middle of October to the middle of November 2011 covering seventy days. Surface and subsurface data were obtained from interpretation of landsat images and shallow hand-auger boreholes. The geological features are distinctly associated with active tectonics. The stratigraphy clearly indicates at least three phases of tectonic activities since the Late Miocene until Holocene. Tectonics of phase one occurred in the Late Miocene; phase two took place in the period from Pliocene to Late Pleistocene, while tectonics phase three is ongoing in the Holocene. Volcanic activity has intensified since the Early Pleistocene. The landsat images show an irregular outline of the northern coast line. This penomenon is interpreted to be the result of tectonic uplift. On the other hand, the southern coast is linear in plan which is interpreted to correlate with tectonic subsidence. Furthermore, stratigraphic correlation shows that depositional environment changed vertically due to a local subsidence. The northern researched area is occupied by Pleistocene volcanic eruption centres, whilst the younger ones tend to shift southward. This fact tends to indicate that the subduction zone moved southward slowly.

Melanic and Fulvic Andisols in Volcanic Soils derived from some Volcanoes in West Java Rina Devnita
Indonesian Journal on Geoscience Vol 7, No 4 (2012)
Publisher : Geological Agency

DOI: 10.17014/ijog.v7i4.149Melanic and fulvic Andisols are the great groups in the classification of volcanic soils Andisols, which describe the soils with high organic carbon content in the epipedon. The organic C must be more than 6% in the upper 30 cm with the value and chroma are 2 or less for melanic and more than 2 for fulvic. Melanic epipedon also has to have the melanic index that is 1.70 or less. The objective of this study is to investigate the melanic and fulvic Andisols in volcanic soils that developed under pine forest vegetation (Pinus merkusii) from different parent materials and ages of Mount Tangkuban Parahu (andesitic, Holocene) and Mount Tilu (basaltic, Pleistocene). The method used was a descriptive comparative survey of three profiles in Mount Tangkuban Parahu and three profiles in Mount Tilu. Analyses were done for each horizon in the profiles comprising the investigation of andic soil properties through the analyses of organic C, bulk density, Al + ½ Fe (ammonium oxalate), and P-retention. The investigations were continued by further calculation of organic C content and by investigation of soil colour with Munsell Soil Colour Chart. The results showed that the two profiles in Mount Tangkuban Parahu and two profiles in Mount Tilu are fulvic Andisol. No melanic Andisols were found in both locations. Pine forest vegetation encourages the formation of fulvic Andisols were derived from andesitic-Holocene parent materials or basaltic-Pleistocene parent materials.

Supergene Enriched, Intrusion Related Low Suphidation Deposit, Binebase-Bawone, North Sulawesi, Indonesia A. Wisanggono; P. Abaijah; K. Akiro; D. Pertiwi; R. Aditya Sauzy
Indonesian Journal on Geoscience Vol 7, No 4 (2012)
Publisher : Geological Agency

DOI: 10.17014/ijog.v7i4.150Gold mineralization at East Asia Minerals’ Binebase Prospect on Sangihe Island displays controls to mineralization typical of other Pacific Rim Intrusion related low sulphidation systems. Better gold grades are localized on EW dilatant structures at the intersection of NW trending structural corridors. Mineralization at Binebase was previously interpreted as being hosted in a high sulphidation style of alteration system. This assumption was based on surface observations of alunite and what was thought to be residual vuggy silica. Recent observations indicate that the alunite is a supergene mineral in nature and that the vuggy silica is the boxworked remnants of silica + pyrite alteration. Precious metal grades decline moving away from feeder structures and there has been significant supergene enrichment of gold in the oxide zone. Exploration drilling completed in 2008 by East Asia Minerals Indonesia resulted in an inferred resource of approximately 835,000 oz of contained gold at a cut off grade of 0.25 g/t Au. This resource included both oxide and hypogene sulphide mineralization. Drilling was reinitiated in 2011 to change the inferred to indicated resource, that drilling programme continued at the time of this publication. Various geophysical techniques were employed at both prospect and regional scales to aid exploration. Ground magnetics defined hydrothermal alteration and magnetite destruction which was coincident with mineralization at both Binebase and Bawone and an Induced Polarisation survey also produced an anomaly which was coincident with disseminated fine sulphide associated with clay alteration within the hydrothermal alteration. The southern part of the island was covered by an airborne geophysical survey in an attempt to understand the regional structural controls on mineralization and to define additional areas of hydrothermal alteration.

Shell Bed Identification of Kaliwangu Formation and its Sedimentary Cycle Significance, Sumedang, West Java Aswan Aswan; S Rijani; Y. Riza
Indonesian Journal on Geoscience Vol 8, No 1 (2013)
Publisher : Geological Agency

DOI: 10.17014/ijog.v8i1.151Kaliwangu Formation cropping out around Sumedang area contains mollusk fossils dominated by gastropods and bivalves. In terms of sequence stratigraphy, each sedimentary cycle generally consists of four shell bed types: Early Transgressive Systems Tract (Early TST) deposited above an erosional surface or sequence boundary, that is characterized by shell disarticulation, trace fossils, gravelly content, no fossil orientation direction, and concretion at the bottom; Late Transgressive Systems Tract (Late TST) identified by articulated (conjoined) specimen in its life position, that shows a low level abration and fragmentation, adult specimen with complete shells, and variation of taxa; Early Highstand Systems Tract (Early HST) characterized by adult taxa that was found locally in their life position with individual articulation, juvenile specimens frequently occured; Late Highstand Systems Tract (Late HST) determined as multiple-event concentrations, disarticulated shell domination, and some carbon or amber intercalation indicating terrestrial influence. Shell bed identification done on this rock unit identified nineteen sedimentary cycles.

The Potential of Eocene Shale of Nanggulan Formation as a Hydrocarbon Source Rock S. Winardi; B. Toha; M. Imron; D. H. Amijaya
Indonesian Journal on Geoscience Vol 8, No 1 (2013)
Publisher : Geological Agency

DOI: 10.17014/ijog.v8i1.152In western Indonesia, Eocene shale is generally considered as a potential source rock. The Nanggulan Formation outcropping at Kulonprogo Yogyakarta consists of a shale interval of Eocene in age. Analysis of its organic material content, kerogen type, and maturity level were conducted to know its potential. The laboratory analysis of eleven samples were done to measure its TOC content. Samples with TOC > 0.5% then were analyzed to measure its Rv and TAI. Maturity level was also calculated by TTI from burial history model. The result of analysis shows there are various TOC contents and seven samples of them are categorized into a good-excellent class (TOC > 1%). Kerogen content of those samples is type III (non fluorescene amorphous-humic kerogen). One sample has a good indication of hydrocarbon formation (PY = 9.0 mg HC/g rock). Unfortunately thermal maturity level of the samples is immature (highest Rv 0.39, Tmax 422oC, and TAI 2). Otherwise, TTI calculation result from subsurface burial history modelling indicates that some areas are mature having reached gas window since 0.4 mya, especially in the area which had been influenced by a volcanic intrusion at Oligocene (28.5 mya). Therefore, the Nanggulan Formation shale has a potential capacity as a source rock with some limitation in maturity level.

Depositional Environment of Fine-Grained Sedimentary Rocks of the Sinamar Formation, Muara Bungo, Jambi M. Heri Hermiyanto Zajuli; H. Panggabean
Indonesian Journal on Geoscience Vol 8, No 1 (2013)
Publisher : Geological Agency

DOI: 10.17014/ijog.v8i1.153The research area is situated in the northwestern side of South Sumatra Basin, which is a part of Muara Bungo Regency, Jambi Province. The Oligocene Sinamar Formation consists of shale, claystone, mudstone, sandstone, conglomeratic sandstone, and coal-seam intercalations. This research was focused on fine sedimentary rock of Sinamar Formation, such as shale, claystone, and mudstone. Primary data were collected from SNM boreholes which have depths varying from 75 m up to 200 m, and outcrops that were analyzed by organic petrographic method, gas chromatography-mass spectrometry (GC-MS) of normal alkanes including isoprenoids, and sterane. The dominant maceral group is exinite, composed of alginite (3.4 - 18%), and resinite (1.6 - 5.6%), while vitrinite maceral consists of tellocolinite 0.4 - 0.6%, desmocollinite 0.4%, and vitrodetrinite 8.4 - 16.6%. Organic petrography and biomarker analyses show that organic materials of shales were derived from high plants and algae especially Botrycoccus species. Botrycoccus and fresh water fish fossil, found in the shale indicate a lacustrine environment.

The Potential of Ketungau and Silat Shales in Ketungau and Melawi Basins, West Kalimantan: For Oil Shale and Shale Gas Exploration Lauti Dwita Santy; Hermes Panggabean
Indonesian Journal on Geoscience Vol 8, No 1 (2013)
Publisher : Geological Agency

DOI: 10.17014/ijog.v8i1.154The Ketungau and Melawi Basins, in West Kalimantan, are Tertiary intramontane basins of which the potential for economic conventional oil and gas discoveries have not previously been confirmed. The Ketungau Basin is bordered by the Melawi Basin in the south. Besides non-ideal trapping mechanisms, another major problem in these basins is source rock maturation. Nevertheless, both basins are promising to be explored for oil shale and shale gas energy resources. Therefore, the aim of this paper is to give some perspectives on their source rocks, as an input for the evaluation of the potential of unconventional oil and gas. About twenty samples collected from the Ketungau and Melawi Basins were analyzed using pyrolysis and organic petrographic methods. The results show a poor to good quality of source rock potential. The Ketungau shale, which is the main source rock in the Ketungau Basin, is dominated by type III, immature, and gas prone kerogen. The Silat shale, which is the main source rock in the Melawi Basin, is dominated by type II, immature to early mature, mixed gas, and oil prone kerogen. In the field, Ketungau and Silat Formations have a widespread distribution, and are typically 900 m to 1000 m thick. Both the Ketungau and Silat shales occur within synclinal structures, which have a poor trapping mechanism for conventional oil or gas targets, but are suitable for oil shale and shale gas exploration. This early stage of research clearly shows good potential for the future development of unconventional energy within the Ketungau and Melawi Basins.

The August 2010 Phreatic Eruption of Mount Sinabung, North Sumatra Igan S. Sutawidjaja; O. Prambada; D. A. Siregar
Indonesian Journal on Geoscience Vol 8, No 1 (2013)
Publisher : Geological Agency

DOI: 10.17014/ijog.v8i1.155Mount Sinabung, located in Karo Regency, North Sumatra Province, is a strato volcano having four active craters. Since its latest eruption about 1,200 year ago, a phreatic eruption occurred on August 27th, 2010. The eruption took place in Crater-I, which was initiated by a greyish white plume and then followed by black plumes as high as 2000 m above the crater. Altered rock fragments and ash were erupted during this event. The altered rocks show a development of argillic alterations which was formed in the hydrothermal system in depth. The alteration zone is formed along the northeast-southwest and northwest-southeast trend across the three craters. All of the craters are actively discharging solfataric gases, of which sulphur deposits are resulted, and they have been quarried by the local people. The age of the latest magmatic eruption was dated by 14C method from the charcoal sample found in the pyroclastic flow deposits near Bekerah Village.

Maceral Characteristics and Vitrinite Reflectance Variation of The High Rank Coals, South Walker Creek, Bowen Basin, Australia Asep K. Permana; C. R. Ward; L. W. Gurba
Indonesian Journal on Geoscience Vol 8, No 2 (2013)
Publisher : Geological Agency

DOI: 10.17014/ijog.v8i2.156The Permian coals of the South Walker Creek area, with a vitrinite reflectance (Rvmax) of 1.7 to 1.95% (low-volatile bituminous to semi-anthracite), are one of the highest rank coals currently mined in the Bowen Basin for the pulverized coal injection (PCI) market. Studies of petrology of this coal seam have identified that the maceral composition of the coals are dominated by inertinite with lesser vitrinite, and only minor amounts of liptinite. Clay minerals, quartz, and carbonates can be seen under the optical microscope. The mineral matter occurs in association with vitrinite and inertinite macerals as syngenetic and epigenetic mineral phases. The irregular pattern of the vitrinite reflectance profile from the top to the bottom of the seam may represent a response in the organic matter to an uneven heat distribution from such hydrothermal influence. Examination of the maceral and vitrinite reflectance characteristics suggest that the mineralogical variation within the coal seam at South Walker Creek may have been controlled by various geological processes, including sediment input into the peat swamp during deposition, mineralogical changes associated with the rank advance process or metamorphism, and/or hydrothermal effects due to post depositional fluid migration through the coal seam.

Morphostructural Development of Gunungsewu Karst, Jawa Island H. D. Tjia
Indonesian Journal on Geoscience Vol 8, No 2 (2013)
Publisher : Geological Agency

DOI: 10.17014/ijog.v8i2.157Gunungsewu Karst (also known as Sewu karst in the literature) is synonymous with morphology of a carbonate terrain dominated by hills crowned by accordant-level tops that developed in a humid tropical environment by comparatively more rapid dissolution and denudation. In addition, the hills are sinoid to cone-shaped. Surface drainage is negligible compared to subsurface water flow. Abandoned channel segments and spatial arrangements of karst hills have been found to correspond with fracture patterns that are genetically associated with the regional compression direction of Jawa Island. Images derived from space platforms show many landform patterns that were neither known from ground-based nor from aerial photograph study. Landforms arranged in ring, multi-ring, spiral, polygonal, and long linear to serpentine patterns are common beside the expected depressions of dolines, poljes, and uvalas. The orientations of the long linear ridges appear to change systematically from those near the coast to those located inland. These linear ridges are interpreted as depositional fronts, most likely representing breaker zones. The youngest depositional ridge fronts, located nearest to the present shoreline, are parallel to the geological strike of Jawa Island. Toward the island’s interior, linear depositional fronts deviate in orientation by as much as 40o. This is now interpreted to have resulted from counterclockwise rotation of the Gunungsewu microplate since the late Middle Miocene. Similar CCW rotations are indicated by the paleomagnetic orientations of igneous rocks located farther east in the southern range of the island. Active tectonics is expressed in stage-wise net uplift of Gunungsewu whereas regional tilting appears negligible. Stacked and often paired river terraces (thus suggesting land uplift) have been used to relatively date paleoarcheological finds. Very recent uplift on the coast show up in lazy-V limestone notch profiles, and occasionally by stacked notches. At the Klayar coast, slight northward tilt of a few degrees are expressed as counter-regional inclination of a subrecent abrasion platform.

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Ivan Ferdian

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Home Page

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Contact Name Ivan Ferdian

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Location Kota bandung, Jawa barat INDONESIA

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Contact Name
Ivan Ferdian

Contact Email
ivan.ijgbg@gmail.com

Phone
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Journal Mail Official
ivan.ijgbg@gmail.com

Editorial Address
-

Location
Kota bandung,

Jawa barat

INDONESIA