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Geochemical Compositions and Magnetic Susceptibility of Soils from Different Origins: A Case Study in South Lampung, Indonesia Santoso, Nono Agus; Iqbal, Mochamad; Kadja, Grandprix Thomryes Marth
Indonesian Journal on Geoscience Vol 7, No 3 (2020)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.7.3.267-272

DOI:10.17014/ijog.7.3.267-272The study of rock weathering into soil is very important in geophysics. The geochemical and magnetic characteristics of soil were investigated in South Lampung using magnetic susceptibility and X-ray Fluorescence (XRF) measurements to identify the rock origin of the soil. The samples consisted of three soil types, those are granite soil, tuff soil in front of ITERA (Institut Teknologi Sumatra, South Lampung), and tuff soil inside ITERA. The tuffs (in front of and inside ITERA) and granite were taken in and around ITERA. The result showed that granite had the highest magnetic susceptibility value, while tuff soil in front of ITERA had the highest FeO content. Each sample can be distinguished by magnetic susceptibility and FeO content to prove that it can be used as a tool to distinguish the rock origin of soil.

Geochemical Compositions and Magnetic Susceptibility of Soils from Different Origins: A Case Study in South Lampung, Indonesia Santoso, Nono Agus; Iqbal, Mochamad; Kadja, Grandprix Thomryes Marth
Indonesian Journal on Geoscience Vol 7, No 3 (2020)
Publisher : Geological Agency

DOI:10.17014/ijog.7.3.267-272The study of rock weathering into soil is very important in geophysics. The geochemical and magnetic characteristics of soil were investigated in South Lampung using magnetic susceptibility and X-ray Fluorescence (XRF) measurements to identify the rock origin of the soil. The samples consisted of three soil types, those are granite soil, tuff soil in front of ITERA (Institut Teknologi Sumatra, South Lampung), and tuff soil inside ITERA. The tuffs (in front of and inside ITERA) and granite were taken in and around ITERA. The result showed that granite had the highest magnetic susceptibility value, while tuff soil in front of ITERA had the highest FeO content. Each sample can be distinguished by magnetic susceptibility and FeO content to prove that it can be used as a tool to distinguish the rock origin of soil.

Hydrogeochemistry of Natar and Cisarua Hot springs in South Lampung, Indonesia Mochamad Iqbal; Bella Restu Juliarka; Wijayanti Ashuri; Bilal Al Farishi
Journal of Geoscience, Engineering, Environment, and Technology Vol. 4 No. 3 (2019): JGEET Vol 04 No 03 : September (2019)
Publisher : UIR PRESS

Natar Hot Spring is one of the geothermal manifestations that is located in Lampung Province, Indonesia. About 6 km to the east, another hot spring appears with temperature around 40°C with neutral pH called Cisarua Hot Spring. The Natar Hot Spring itself having temperature 47-54°C with 6.23 pH. Based on the geologic map, the appearance of these hot spring is caused by Lampung-Panjang Fault which trending northwest-southeast. Morphology of the research area is showing a flat terrain topography which composed of Quaternary volcanic rock and metamorphic rock in the basement. The nearest volcano that expected to be the heat source of the geothermal system is the Quaternary extinct volcano called Mt. Betung which is located about 15 km to the southwest. The aim of the study is to analyze the geochemistry of the manifestations and calculate the reservoir temperature. Geochemistry analysis result shows both manifestations are bicarbonate which is formed as a steam-heated water or steam condensates. Geothermometer calculation shows that the geothermal reservoir has temperature 150-160°C with approximately 300 m in depth. All manifestations are originated from meteoric water according to stable isotope analysis D and δ18O data and interacting with carbonate-metamorphic rock beneath the surface based on 13C isotope value. A further geophysics study is needed to determine where the heat comes from.

Geochemical Compositions and Magnetic Susceptibility of Soils from Different Origins: A Case Study in South Lampung, Indonesia Nono Agus Santoso; Mochamad Iqbal; Grandprix Thomryes Marth Kadja
Indonesian Journal on Geoscience Vol 7, No 3 (2020)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.7.3.267-272

DOI:10.17014/ijog.7.3.267-272The study of rock weathering into soil is very important in geophysics. The geochemical and magnetic characteristics of soil were investigated in South Lampung using magnetic susceptibility and X-ray Fluorescence (XRF) measurements to identify the rock origin of the soil. The samples consisted of three soil types, those are granite soil, tuff soil in front of ITERA (Institut Teknologi Sumatra, South Lampung), and tuff soil inside ITERA. The tuffs (in front of and inside ITERA) and granite were taken in and around ITERA. The result showed that granite had the highest magnetic susceptibility value, while tuff soil in front of ITERA had the highest FeO content. Each sample can be distinguished by magnetic susceptibility and FeO content to prove that it can be used as a tool to distinguish the rock origin of soil.

Geothermal System in Parang Wedang, Yogyakarta, Indonesia Mochamad Iqbal; Bella Restu Juliarka
Journal of Engineering and Technological Sciences Vol. 54 No. 4 (2022)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2022.54.4.6

Geothermal manifestations in Parangtritis, Indonesia, known as Parang Wedang Hot Spring, indicate a geothermal system in the subsurface. This circumstance motivated our research to model the Parang Wedang geothermal system in order to determine its subsurface conditions. Geological mapping, the geophysical method, and geochemical analysis were integrated to produce a conceptual model of the Parang Wedang geothermal system. The study area consists of structural hills, karst hills, and eolian plains with andesite breccias, limestone, andesite, and sand deposits as lithological variations. The results of magnetic modeling indicate that the research area is associated with the presence of an andesite intrusion and shows a NE-SW trending geological structure that is thought to be a path for hydrothermal fluid to the surface. Geochemical analysis was performed at two hot springs with temperatures of 47 °C and 49 °C. Geothermometer calculation showed that the geothermal reservoir in Parang Wedang has a temperature of 100 to 120 °C, a depth of about 180 to 285 m, and can be classified as a low enthalpy geothermal system.

Mineral analysis in rocks using XRD and Petrography Muhamad Ragil Setiawan; Mochamad Iqbal; Rahmat Nawi Siregar
Journal of Science and Applicative Technology Vol 2 No 1 (2019): ICoSITeR Special Edition
Publisher : Lembaga Penelitian dan Pengabdian Masyarakat (LPPM), Institut Teknologi Sumatera, Lampung Selatan, Lampung, Indonesia

Rock formation in a region is influenced by many factors such as tectonic and volcanic systems of the area. Both activities will affect the microstructure of the rock. This study analyzes mineral composition in three different rocks. We display the digital image that obtained from XRD and petrography. Rock samples were taken from some formations around Lampung. The analysis was performed on three different rocks: granite, andesite, and schist using XRD and petrography. The granite-R1 sample shows the result of mineral content present in the rock that is quartz, alkali feldspar, plagioclase, biotite. The andesite-R2 sample consists of plagioclase, orthopyroxene, biotite, and volcanic glass. The Schist-R3 sample consist of quartz, muscovite, calcite.

Morphological Analysis of Anak Krakatau Volcano after 22 December 2018 Eruption using Differential Interferometry Synthetic Aperture Radar (DInSAR) Mochamad Iqbal; Anjar Dwi Asterina Denhi; Kristianto; Ardy Prayoga
Journal of Geoscience, Engineering, Environment, and Technology Vol. 8 No. 2 (2023): JGEET Vol 08 No 02 : June (2023)
Publisher : UIR PRESS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25299/jgeet.2023.8.2.11651

Anak Krakatau Volcano is an active volcano located in the Krakatau Complex, Sunda Strait, Indonesia. On 22 December 2018, the volcano experienced a major eruption that led to a tsunami that devastated the shores of the islands of Java and Sumatra and killed up to 437 people. The eruption also destroyed the volcanoâ€™s body and change its shape drastically and forming a large crater in the southwestern part. After that eruption, the volcano continues to grow up. This research aims to analyze the deformation of the Anak Krakatau Volcano post-2018 eruption by using the differential interferometry SAR method (DInSAR). In order to support the analysis, we additionally compare the DInSAR result with tectonic-volcanic activity. Sentinel 1-A type SLC satellite imagery data from 5 June 2019 to 7 January 2020; consisting of 19 images or 18 pairs as master and slave were used to producing a deformation map. DInSAR result shows the volcano was generally experiencing deflation during the period, ranging from -1.03 to -4.81 cm (-3.01 cm average). However, inflation also occurred ranging from 0 to 5.99 cm, correlating with shallow and deep volcanic activity and followed by eruptions in October 2019 when the highest activities were observed. Furthermore, coherence value should be highly considered along with DInSAR processing, and this research allows that coherence to be acceptable.

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