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GEOMORPHIC INDICES AND FAULT SEGMENTATION INDICATION OF MENANGA FAULT AT PESAWARAN, LAMPUNG Hendrawan, Rezki Naufan; Draniswari, Windi Anarta; Bakhtiar, Agim Yustian; Widiatama, Angga Jati
JGE (Jurnal Geofisika Eksplorasi) Vol 9, No 3 (2023)
Publisher : Engineering Faculty Universitas Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23960/jge.v9i3.287

Abstract

Remote sensing and GIS are playing important roles in geomorphology and hazard risks analysis. Pesawaran area located near the Menanga Fault and recently on the risk of earthquake that happened along this fault.  Thus, it is essential to investigate the area actively affected by Menanga Fault as preliminary research about hazard risk related to Menanga Fault. The morphometry method based on DEMNAS and Landsat 8 was applied to evaluate the zone affected by Menanga Fault, and fracture data analysis was conducted to consider the possibility of fault segmentation resulting from its mechanism. The study area can be divided into 3 zones; zone A is greatly affected by Menanga Fault activity, zone B is affected by Menanga Fault and Mt. Pesawaran development, and zone C is tectonically less affected. Zone A landforms were not only formed as a result of Menanga Thrust fault but also the strike-slip fault segment.  Fault segmentation exists in this zone with different mechanisms (strike-slip and dip-slip), producing lineaments with different trends, and differentiation of river patterns.
Metamorphic Complex Deformation in North Bangka Island Based on Macrostructures and Microstructures Evidences Hendrawan, Rezki; Draniswari, Windi Anarta; Wahyuni, Fitri Indah; Sapiie, Benjamin; Basuki, Nurcahyo Indro
Journal of Geoscience, Engineering, Environment, and Technology Vol. 9 No. 2 (2024): JGEET Vol 09 No 02 : June (2024)
Publisher : UIR PRESS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25299/jgeet.2024.9.2.13379

Abstract

The northern Bangka Island is composed of Pemali metamorphic complex which is indicated by the collision between Indochina and Sibumasu blocks. These features are interesting to observe because the metamorphic rocks could be recorded in some geological structures at different times. The study began by conducting field observation on Pemali Metamorphic Complex as objects. Field observation aims to collect lithological data, structural data, and oriented rock samples. The results of field pitching were processed to determine macrostructures, microstructures, and mineral distribution. The data was analyzed based on kinematic, descriptive, and deformation mechanisms to determine the deformation patterns that occurred in the study area. Field and oriented thin section data show structures and occurred in different deformation conditions. The analysis based on macrostructures and microstructures showed that the northern part of Bangka Island experienced three different deformation phases. Deformation begins with the formation of folds that are associated with collisions between Sibumasu-Indochina, followed by a second deformation that forms a fold with different verging. Both deformations are formed in the ductile zone and the brittle-ductile transition zone. The third deformation occurs when rocks have been lifted to the surface by the presence of faults, joints, and veins. The sequence of the deformation model is similar to the deformation experienced in the Bentong-Raub suture zone formed in the shear zone.
GEOMORPHIC INDICES AND FAULT SEGMENTATION INDICATION OF MENANGA FAULT AT PESAWARAN, LAMPUNG Hendrawan, Rezki Naufan; Draniswari, Windi Anarta; Bakhtiar, Agim Yustian; Widiatama, Angga Jati
JGE (Jurnal Geofisika Eksplorasi) Vol. 9 No. 3 (2023)
Publisher : Engineering Faculty Universitas Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23960/jge.v9i3.287

Abstract

Remote sensing and GIS are playing important roles in geomorphology and hazard risks analysis. Pesawaran area located near the Menanga Fault and recently on the risk of earthquake that happened along this fault.  Thus, it is essential to investigate the area actively affected by Menanga Fault as preliminary research about hazard risk related to Menanga Fault. The morphometry method based on DEMNAS and Landsat 8 was applied to evaluate the zone affected by Menanga Fault, and fracture data analysis was conducted to consider the possibility of fault segmentation resulting from its mechanism. The study area can be divided into 3 zones; zone A is greatly affected by Menanga Fault activity, zone B is affected by Menanga Fault and Mt. Pesawaran development, and zone C is tectonically less affected. Zone A landforms were not only formed as a result of Menanga Thrust fault but also the strike-slip fault segment.  Fault segmentation exists in this zone with different mechanisms (strike-slip and dip-slip), producing lineaments with different trends, and differentiation of river patterns.
Peran Kontaminasi Kerak pada Diferensiasi Magma Pembentuk Batuan Vulkanik Sungai Ampalas, Mamuju, Sulawesi Barat Draniswari, Windi Anarta; Kusuma, Sekar Indah Tri; Adimedha, Tyto Baskara; Sukadana, I Gde
EKSPLORIUM Vol. 41 No. 2 (2020): NOVEMBER 2020
Publisher : BRIN Publishing

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17146/eksplorium.2020.41.2.6040

Abstract

Anomalous radiometry has been found in Ampalas River Area on volcanic rock boulder. The values measured from gamma spectrometer are 787 ppm eU and 223 ppm eTh. This discovery is promising for exploration development. Further study need to figure the radioactive mineral bearing rock characteristic from in-situ samples. The research aim is to determine the petrology and geochemical characteristics of Ampalas volcanic rocks as preliminary study to find radioactive mineral accumulation process of Ampalas volcanic rocks. The methodologies are field observation, rock sampling, petrography, and X-Ray fluorescence (XRF) analyses. The Ampalas volcanic rocks consist of phonolite, phoidite, and phoid syenite. Their textures are porphyritic, flow, pyroxene rim, zoning, pseudo-leucite, corrosion, mafic inclusions, and sieve. The geochemical characteristics show high alkalinity and radioactive mineral enrichment disseminating on rock. The magmatic processes which play a significant role in radioactive mineral-bearing rocks formation are crystal fractionations (leucite and alkaline feldspar fractionations), continental crust assimilation, and magma mixing. Long interaction between magma and crust creates advanced magma differentiation causing higher uranium and thorium accumulation.
Distribution and Mineralogical Characteristic of Raya Volcanics, West Kalimantan Draniswari, Windi Anarta; Pratiwi, Fadiah; Ngadenin; Sukadana, I Gde; Adimedha, Tyto Baskara; Ciputra, Roni Cahya; Argianto, Ekky Novia Stasia; Aminarthi, Erwina; Supraba, Vertika Dhianda
EKSPLORIUM Vol. 42 No. 2 (2021): NOVEMBER 2021
Publisher : BRIN Publishing

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17146/eksplorium.2021.42.2.6511

Abstract

There are several volcanic rocks in a radius of 150 km from where the Nuclear Power Plant (NPP) site project in West Kalimantan. The Mesozoic volcanic rocks have not been characterized for volcanic hazard evaluation purposes due to their old age. However, the distribution of Raya Volcanic Rocks that covers the site area and the wider area up to 150 kilometers from the site makes this rock group quite important to be characterized to find out how its activities in the past. This paper’s objective is to comprehend the distribution and characteristics of Raya Volcanic Rocks for NPP site volcanic hazard evaluation purposes. Fieldwork and lineament analyses were conducted to map and interpret the distribution of Raya Volcanic Rocks while mineralogical analysis using petrography and micro XRF were conducted to characterize the Raya Volcanic Rocks. The distribution of Raya Volcanic Rocks that relatively show NNW–SSE orientation is probably controlled by the NNW–SSE fault system. The analyses resulted that Raya Volcanic Rocks erupted as lava flows derived from mafic magma as a product of mantle partial melting that underwent crystal fractionation, injection of hotter/more Ca-rich magma, and magma mixing on an open-system magmatic process.