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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.

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Articles 9 Documents

Search results for , issue "Vol 6, No 3 (2019)" : 9 Documents clear

Multi-Ricker Spectral Modeling in the S-transform Domain for Enhancing Vertical Resolution of Seismic Reflection Data Winardhi, Sonny; Pranowo, Waskito
Indonesian Journal on Geoscience Vol 6, No 3 (2019): in-press
Publisher : Geological Agency

We present a relatively straightforward methodology for extending seismic bandwidth and hence enhancing the seismic resolution by performing time-variant deconvolution. We use the generalized S-transform (GST) approach in order to properly compute the time-frequency components of the seismic reflection trace. In estimating the time-variant wavelet, we propose a spectral modeling method named multi-Ricker spectral approximation (MRA). After obtaining the estimated wavelet spectrum at each time sample, a deconvolution filter can then be built and applied in the S-transform domain. This proposed time-variant seismic enhancement method needs neither information on subsurface attenuation model nor assumption that the subsurface reflectivity is random. It is a data-driven methodology which is based on the seismic data only. We validate this proposed method on a synthetic and apply to a field data. Results show that, after enhancement, overall seismic bandwidth can be extended resulting in higher vertical resolution. Correlation with VSP corridor stack at well location ensures that the generated reflection details after enhancement is geologically plausible.

Tephra-stratigraphy and Ash Componentry Studies of Proximal Volcanic Products at Mount Tangkuban Parahu, Indonesia: An Insight to Holocene Volcanic Activity Angkasa, Syahreza S.; Ohba, Tsukasa; Imura, Takumi; Setiawan, Iwan; Rosana, Mega
Indonesian Journal on Geoscience Vol 6, No 3 (2019): in-press
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.6.3.235-253

Tangkuban Parahu Volcano is one of the most active volcanoes in West Java, Indonesia, although most of the recent eruptions were relatively mild (e.g. 2013 eruption). However, there is still little information from the volcanic products in the proximal area. Here, a new documentation from the proximal volcanic succession is provided, including tephra-stratigraphy, componentry analysis, and petrography of volcanic products. Detailed mapping of the proximal area shows that the volcanic products are predominantly composed of alternating fine-clay and coarse ash, lapilli tuff, and pyroclastic breccia within ten tephra units. Componentry of ash particles revealed the presence of five components, associated with hydrothermally altered lithics, oxidized lithics, coherent crystalline lithics, magmatic juvenile, and free crystal in entire eruptive products. These indicate that the subvolcanic hydrothermal system has been developed since the Holocene and associated with a continual introduction of magmatic intrusion. Petrographic observation shows the presence of hydrothermal minerals of quartz or silica accompanied by alunite and kaolinite, representing acidic alteration within the crater-conduit. The existence of a silicified zone indicates that the subvolcanic hydrothermal system played an essential role as a cap-rock of pressurized gas and steam at depth (200-500 m), whereas magmatic injection caused the vapour plume expansion. The observation concluded that the proximal volcanic succession captured the evidence of coupled phreatic and phreatomagmatic activities during the latest development of Mount Tangkuban Parahu.

Multi-Ricker Spectral Modeling in the S-transform Domain for Enhancing Vertical Resolution of Seismic Reflection Data Sonny Winardhi; Waskito Pranowo
Indonesian Journal on Geoscience Vol 6, No 3 (2019)
Publisher : Geological Agency

DOI: 10.17014/ijog.6.3.223-233We present a relatively straightforward methodology for extending seismic bandwidth and hence enhancing the seismic resolution by performing time-variant deconvolution. We use the generalized S-transform (GST) approach in order to properly compute the time-frequency components of the seismic reflection trace. In estimating the time-variant wavelet, we propose a spectral modeling method named multi-Ricker spectral approximation (MRA). After obtaining the estimated wavelet spectrum at each time sample, a deconvolution filter can then be built and applied in the S-transform domain. This proposed time-variant seismic enhancement method needs neither information on subsurface attenuation model nor assumption that the subsurface reflectivity is random. It is a data-driven methodology which is based on the seismic data only. We validate this proposed method on a synthetic and apply to a field data. Results show that, after enhancement, overall seismic bandwidth can be extended resulting in higher vertical resolution. Correlation with VSP corridor stack at well location ensures that the generated reflection details after enhancement is geologically plausible.

Tephra-stratigraphy and Ash Componentry Studies of Proximal Volcanic Products at Mount Tangkuban Parahu, Indonesia: An Insight to Holocene Volcanic Activity Syahreza S. Angkasa; Tsukasa Ohba; Takumi Imura; Iwan Setiawan; Mega Rosana
Indonesian Journal on Geoscience Vol 6, No 3 (2019)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.6.3.235-253

DOI: 10.17014/ijog.6.3.235-253Tangkuban Parahu Volcano is one of the most active volcanoes in West Java, Indonesia, although most of the recent eruptions were relatively mild (e.g. 2013 eruption). However, there is still little information from the volcanic products in the proximal area. Here, a new documentation from the proximal volcanic succession is provided, including tephra-stratigraphy, componentry analysis, and petrography of volcanic products. Detailed mapping of the proximal area shows that the volcanic products are predominantly composed of alternating fine-clay and coarse ash, lapilli tuff, and pyroclastic breccia within ten tephra units. Componentry of ash particles revealed the presence of five components, associated with hydrothermally altered lithics, oxidized lithics, coherent crystalline lithics, magmatic juvenile, and free crystal in entire eruptive products. These indicate that the subvolcanic hydrothermal system has been developed since the Holocene and associated with a continual introduction of magmatic intrusion. Petrographic observation shows the presence of hydrothermal minerals of quartz or silica accompanied by alunite and kaolinite, representing acidic alteration within the crater-conduit. The existence of a silicified zone indicates that the subvolcanic hydrothermal system played an essential role as a cap-rock of pressurized gas and steam at depth (200-500 m), whereas magmatic injection caused the vapour plume expansion. The observation concluded that the proximal volcanic succession captured the evidence of coupled phreatic and phreatomagmatic activities during the latest development of Mount Tangkuban Parahu.

The Gondwanan Green Alga Tasmanites sp. in the Permian Lacustrine Deposits of West Timor Eko Budi Lelono
Indonesian Journal on Geoscience Vol 6, No 3 (2019)
Publisher : Geological Agency

DOI: 10.17014/ijog.6.3.255-266This paper discusses a palynological research on the Permian lacustrine sediments of West Timor. Ten outcrop samples were collected from a 5 m high cliff. Lithologically, the outcrop mostly consists of noncalcareous black shale showing papery structures and forms part of Bisane Formation. Palynomorphs extracted from the studied samples are rich, but of a low diversity indicating a non-marine environment. More than 80% of pollen assemblages are of the green alga Tasmanites sp., whilst the rest are mostly represented by striate and non-striate bisaccate pollen and trilete spores which indicate a Permian age. The chromatograms of GC and GCMS (saturate) indicate that the studied samples were deposited in a lacustrine environment of an anoxic to suboxic condition. Furthermore, in term of petroleum exploration, abundant Tasmanites sp. is believed to be the biological source for tricyclic terpanes which are well known as the primary source of hydrocarbons. This discovery offers an excellent opportunity for establishing a new petroleum system within the Paleozoic sequences of Timor Island.

Tertiary Sequence Stratigraphy of Bird Head Area, Eastern Indonesia Syaiful Alam; Djadjang Jedi Setiadi
Indonesian Journal on Geoscience Vol 6, No 3 (2019)
Publisher : Geological Agency

DOI: 10.17014/ijog.6.3.267-278 A long depositional period of Papua limestone called Kais Formation, which is overlain by clastic sediments of Steenkool Formation, reflects an interesting stratigraphic architecture in the West Papua region. Using seismic stratigraphic method of five stacking patterns, forestepping, downstepping, upstepping, backstepping, and seismic facies (parallel, prograding clinoform, channel fill, mounded) have been observed. Chronostratigraphic reconstruction was completed to figure out the depositional units in space and time. This study reveals the lowstand deposit during Early to Middle Eocene (LST), transgressive-highstand carbonate deposit during Middle Eocene to Middle Oligocene, and transgressive-highstand silisiclastic (TST-HST) deposit during Middle Miocene - Late Pliocene.

Determination of Hypocentre and Seismic Velocity Structure in Guntur Volcano Using Seismic Data from 2010 to 2014 Ahmad Basuki; Andri Dian Nugraha; Sri Hidayati; Hetty Triastuty
Indonesian Journal on Geoscience Vol 6, No 3 (2019)
Publisher : Geological Agency

DOI: 10.17014/ijog.6.3.279-289Guntur Volcano was in a dormant state even though its seismicity had increased on April, 2013 and August, 2013. In this study, determination of hypocentre and seismic velocity structure was conducted using seismic data from 2010 to 2014 as recorded by a seismic station of the Centre for Volcanology and Geological Hazard Mitigation of Indonesia (CVGHM). Volcano-Tectonic (VT) earthquakes were identified and carefully picked for P-and S-wave arrival times. More than 600 events of VT earthquakes from 2010 - 2014 were located using maximum likelihood estimation algorithm. The initial 1-D seismic velocity was calculated using Velest method in order to get the initial velocity as the input for the tomographic inversion. The results show distribution of VT hypocentres were clustered in three regions, namely Guntur Volcano, Kamojang geothermal area, and Darajat geothermal area. At the Guntur Volcano region, the VT events were located mostly at the northern part of the crater with the depth of hypocentre ranges from 0 - 4 km. The distribution of the VT events made alignment from the southwest to the northeast with the depth of hypocentre mostly ranges from 0 - 2 km at Kamojang region. Meanwhile, at Darajat geothermal area, the VT events were located at the depth of 0 - 2 km and made alignment from the southeast to the northwest. The low velocity zone associated with hot material or fluids was located at the depth of 5 km beneath the Guntur Crater. The location of VT earthquakes at the depth of 0 - 4 km beneath Guntur Crater was coincided with the area with high Vp and Vs anomalies. The low velocity zones were also found at Kamojang Crater and Cipanas hotspring area. It was predicted that the low velocity zone at the Kamojang Crater was related to a high temperature of the vapour system, whereas the reservoir of water was preferred to be dominated at the Cipanas hotspring.

Morphotectonics of Mount Rendingan Area Related To the Appearances of Geothermal Surface Manifestations Dewi Gentana; Nana Sulaksana; Emi Sukiyah; Euis Tintin Yuningsih
Indonesian Journal on Geoscience Vol 6, No 3 (2019)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.6.3.291-309

DOI: 10.17014/ijog.6.3.291-309The researched area is situated at Mount Rendingan and its surrounding area, Lampung Province, the southern part of Sumatra Island. It has a big potential of geothermal resource in line with a unique graben like bowl landform and geothermal surface manifestations. This research was carried out using remote sensing and field observation methods. The remote sensing method used topography and Shuttle Radar Topography Mission -Digital Elevation Model (SRTM-DEM) maps to analyze morphotectonic attributes, and the result was validated by morphotectonic data analysis from field observation. The purpose of this research is to evaluate the relation between morphotectonic and the appearances of geothermal surface manifestations. The interpretation of SRTM-DEM and topographic maps are supported by morphotectonic analyses,which indicate that the geothermal surface manifestations in this area are controlled by tectonic activity. It has various levels of lift which are shown by the values of valley height weight ratio (Vf) from 0.16 to 3.31 and the values of mountain front sinuosity (Smf) from 1.05 to 2.09. The morphotectonic characteristics can describe the geological structure activity levels which are reflected in the landform and its rock. The volcanic areas consist of igneous rocks which have small primary permeabilities. However, the development of geological structure can cause fractures in the rock that step in as a medium for passing geothermal fluid from depth to surface. They are found on the fault intersection zone system trending NE-SW and NW-SE, NNE-SSW and NNW-SSE, and WE system directions that indicate the fault system is correlated with the appearances of geothermal manifestations.

Tectonic Activity Phases of Cenozoic Period in Xuat Hoa Area, Bac Kan Province, Northeast Region, Vietnam Truong Thanh Phi
Indonesian Journal on Geoscience Vol 6, No 3 (2019)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.6.3.311-325

DOI: 10.17014/ijog.6.3.311-325This paper presents the analytical results of a hundred and three striations from twenty-five survey locations along 3B highway in Xuat Hoa area, Bac Kan Province, Vietnam. The analytical results have determined four main phases of tectonic activity: NW−SE, E−W, NE−SW, and N−S. The first phase, the compressive stress state in the direction of NW−SE, caused the right lateral strike-slip motion of faults in the direction of E−W and the left lateral strike-slip motion of faults in the direction of N−S. The second phase, the compressive stress state in the direction of E−W, caused the left lateral strike-slip motion of faults in the direction of NW−SE and the right lateral strike-slip motion of faults in the direction of NE−SW. The third phase, the compressive stress state in the direction of NE−SW, caused the left lateral strike-slip motion of faults in the direction of E−W and the right lateral strike-slip motion of faults in the direction of N−S. The final phase, the compressive stress state in the direction of N−S, caused the left lateral strike-slip motion of faults in the direction of NE−SW and the right lateral strike-slip motion of faults in the direction of NW−SE. In addition, these stress states also created thrust faults in the directions of NE−SW, N−S, NW−SE, and E−W. Based on the analytical results, field investigation, and previous studies, this study proposes the order of the main compressive stress states in the directions of 1) NW−SW, 2) E−W, 3) NE−SW, and 4) N−S.

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Home Page

OAI Link

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Contact Name Ivan Ferdian

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Abstract

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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