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Yusi Firmansyah
Faculty of Geological Engineering, Universitas Padjadjaran
Earth & Planetary Sciences Engineering

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Journal : Journal of Geosciences and Applied Geology

 1 
STRATIGRAPHY AND PETROGRAPHY OF ROCKS IN KARANGTENGAH VILLAGE AND SURROUNDINGS, BABAKAN MADANG SUB-DISTRICT, BOGOR DISTRICT, WEST JAVA PROVINCE REZA MOHAMMAD GANJAR GANI; Yusi Firmansyah; Nisrina Nadellia Putri; Tri Septianto Efendi; Kurnia Arfiansyah Fachrudin
Journal of Geological Sciences and Applied Geology Vol 7, No 3 (2023): Journal of Geological Sciences and Applied Geology
Publisher : Faculty of Geological Engineering, Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24198/gsag.v7i3.53012

Abstract

Stratigraphy and petrography, integral components of geological science, are crucial for identifying mineral composition, rock texture, and characteristics, as well as understanding relationships between layers and layer positions. This study is located in Karangtengah Village and its Nearby Surroundings, Babakan Madang District, Bogor Regency, West Java Province. Physiographically, the study area is included in the Bogor Zone (Van Bemmelen, 1949). The research site is also incorporated in the Geological Map of Bogor Sheet, West Java. And specifically this research was conducted in the Cileungsi River. This river is included in the Jatiluhur Formation (Sudjatmiko, 1972). Stating the purpose of geological mapping, such as understanding regional geology, identifying mineral resources, or assessing geological hazards. Then, data collection in the field, such as conducting detailed field surveys to observe and record geological features, using field notebooks, GPS for plotting, and cameras for documentation, collecting rock samples for laboratory analysis (Petrography analysis and microfossil analysis). As a result of this study, there are four rock units in the Karangtengah area, with the order of formation from the oldest to the youngest. Firstly, Claystone Unit (Tmbl) consists of mudstones and sandstones, with fossils of P. transitoria and G. peripheroronda indicating an Early Miocene age (N8) and the depositional environment is the Outer Neritic. Second, the Old Andesite Intrusion (At) consists of andesite igneous rocks with Middle Miocene age and deposited in a terrestrial environment. Third, the Tuff Unit (Qt) is dominated by pyroclastic tuff rocks with Pleistocene age and deposited in a terrestrial environment. Finally, the Andesite Unit (Am) consists of andesite igneous rocks younger than the Pleistocene, penetrating the Tuff Unit (Qt) and the Claystone Unit, and deposited in a terrestrial environment.
Estimation of Shale Content Calculation using log data in Kutai Basin Yusi Firmansyah; Muhammad Rafie; Reza Mohammad Ganjar Gaji
Journal of Geological Sciences and Applied Geology Vol 7, No 1 (2023): Journal of Geological Science and Applied Geology
Publisher : Faculty of Geological Engineering, Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24198/gsag.v7i1.49332

Abstract

Log data from the study area is located in the Kutai Basin, precisely in the Pulubalang Formation which is used to calculate the estimated shale content. Shale content estimation is one of the petrophysical parameters. In this study, the calculation of shale content estimation uses 3 methods, namely linear, Clavier and Stieber methods. The results of the calculation will provide the volume value of shale in the research area. In the process of calculating the shale content is calculated by separating the range of zones that will be calculated after determining the shale baseline by positioning the zone line on the highest gamma ray log and sand baseline on the lowest gamma ray which then shows the shale content contained in the zone to be analyzed. The results of the calculation of shale content in well A at a depth of 2750 - 3224 m ranged from 36.57% to 71.99%. The results of the analysis of clay content in the study area have an average clay content of 49.22%, meaning that the more clay content, the smaller the permeability and resistivity values will be and will increase the water saturation value.
ANALYSIS OF GEOMORPHOLOGICAL ASPECTS OF SURADE SUB-DISTRICT, SUKABUMI DISTRICT, WEST JAVA Yusi Firmansyah; Nur Khoirullah; Moh Fahrul Yahya
Journal of Geological Sciences and Applied Geology Vol 7, No 1 (2023): Journal of Geological Science and Applied Geology
Publisher : Faculty of Geological Engineering, Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24198/gsag.v7i1.49334

Abstract

The current form of the earth's surface romance is the result of geological processes that have taken place during the geological period which can show how the characteristics and distribution of the constituent rocks. This research was conducted to find out how the geomorphological conditions by analyzing the aspects of morphography, morphometry, and morphogenetics as a form of geomorphology in an area. The research location is in Mekarjaya Village, Ciemas Sub-district, Sukabumi Regency, West Java, which has geomorphological conditions influenced by the activity of an old submarine volcano which was then uplifted and experienced an intensive tectonic process. The method used in this study combines qualitative and quantitative aspects supported by satellite imagery, data processing applications, and references from previous research results. The results of this study show that there are 2 geomorphological units, namely the Slightly Steep Volcanic Hills Unit and the Steep Volcanic Hills Unit with the distribution of andesitic lava and volcanic breccia rocks. The drainage pattern that develops is rectangular.
SWELLING POTENTIAL OF CLAY SOIL KALIWANGU FORMATION IN CIBOGO DISTRICT, SUBANG REGENCY AREA BASED ON ITS BASIC PHYSICAL PROPERTIES Rio Akmal Rizky Prasetio; Raden Irvan Sophian; Yusi Firmansyah; Nur Khoirullah
Journal of Geological Sciences and Applied Geology Vol 7, No 2 (2023): Journal of Geological Sciences and Applied Geology
Publisher : Faculty of Geological Engineering, Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24198/gsag.v7i2.49958

Abstract

The research is conducted in Cibogo District, Subang Regency. Focus of the research is taking samples in area inside Kaliwangu Formation by doing field observation and field sampling using disturbed sample method then it will be tested in laboratory for its basic physical properties. Result of its basic physical properties will be analyzed to determine their swelling potential by taking 5 sample of soil from Kaliwangu Formation. Based on sieve analysis every sample of Kaliwangu Formation (Pk) have more than 50% of clay fraction for each sample, and based on Atterberg limit test Kaliwangu Formation (Pk) samples are dominated by Silt High Plasticity (MH) soil with 3 samples of the MH type and only 2 samples of the CH type. According to consistency limit test of Kaliwangu Formation (Pk) soil, the swelling potential can be determined by classify it based on liquid limit (%) and plasticity index (%) using swelling potential classification. Using the soil consistency value, especially the liquid limit value and the plasticity index value, it can be classified as the swelling potential of Kaliwangu Formation (Pk) classified as high - very high potential with a very high dominance.
SOIL ERODIBILITY AND ITS EROSION POTENTIAL IN SADAWARNA DAN AND SURROUNDING AREA, CIBOGO DISTRICT, SUBANG REGENCY, WEST JAVA PROVINCE Salsabila Nur Alpionisa; Zufialdi Zakaria; Nur Khoirullah; Raden Irvan Sophian; Yusi Firmansyah
Journal of Geological Sciences and Applied Geology Vol 7, No 2 (2023): Journal of Geological Sciences and Applied Geology
Publisher : Faculty of Geological Engineering, Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24198/gsag.v7i2.49995

Abstract

The Sadawarna Dam and its surroundings, which are located in Subang Regency, are currently under construction. Change in land use caused by the construction occurred. Land management and soil conservation are needed to prevent uncontrolled erosion because it can caused slopes in critical condition, flood occurred in the downstream areas of river, and silting of dam. One of the information in land management and soil conservation is by identifying the soil erodibility which aims to find out the sensitivity of the soil to erosion in the research area. Soil erodibility affected by grain size distribution, soil structure, soil organic matter, and soil permeability. In this research area, the soil erodibility was calculated based on disturbed sample in the field which was then tested in the laboratory. The laboratory tests include sieve analysis, hydrometer analysis, and %c organic. Soil permeability obtained from previous studies. The research area is dominated by clay-sized soil which are the result of weathered claystone in Subang Formation. Soil erodibility value in the research area ranged from 1,100 – 0,448 t ha h/ha MJ cm with dominance of low soil erodibility classes. The dominance of clay-sized soil causes low soil erodibility value because clay sized soil has cohesive properties so it tends to be difficult to erode.
Slope Stability Analysis of East Ring Road Construction at Sadawarna Dam With Shear Strength Reduction Method Rafino Kurnia Putra; Zufialdi Zakaria; Muhammad Kurniawan Alfadli; Raden Irvan Sophian; Nur Khoirullah; Yusi Firmansyah
Journal of Geological Sciences and Applied Geology Vol 7, No 3 (2023): Journal of Geological Sciences and Applied Geology
Publisher : Faculty of Geological Engineering, Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24198/gsag.v7i3.50589

Abstract

Slope stability has been a problem that studied on geotechnical works for the uncertainties such as varieties of soil behaviours to unpredicted failure of measurements and samplings. The Limit Equilibrium Method (LEM) has been popular for decades for its convenience but cannot determine displacement thus the result could be uncertain. As computational calculations have been developed, the Finite Element Method (FEM) began to use as a tool to not only determine factor of safety, but also determine displacement and forces that affect slope’s stability. This research was done to analysed slope stability using Shear Strength Reduction (SSR) and compared it to general method such as Limit Equilibrium Method (LEM). The research was conducted on a section in Sadawarna DAM ring road area, Subang, West Java. Slope on research area was divided into two layers with the bottom layer relatively non-cohesive compared to the top of layer. Both soil however dominantly consist with fine grain soil such as silt and clay. The upper layer of slope can contain more water with liquid limit of 73,46% compared to the lower layer with 68,27% liquid limit.  Simulation result showed slope that analysed using SSR method has Factor of Safety (FoS) 0,12 lower than LEM method. SSR method could be used to analysed pessimistic value at worst scenario and could predicted deformation of slope.
Co-Authors Kurnia Arfiansyah Fachrudin Moh Fahrul Yahya Muhammad Kurniawan Alfadli Muhammad Rafie Nisrina Nadellia Putri Nur Khoirullah Nur Khoirullah Raden Irvan Sophian Rafino Kurnia Putra Reza Mohammad Ganjar Gaji REZA MOHAMMAD GANJAR GANI Rio Akmal Rizky Prasetio Salsabila Nur Alpionisa Tri Septianto Efendi Zufialdi Zakaria