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All Journal Bulletin of Scientific Contribution : Geology Jurnal Geologi dan Sumberdaya Mineral (Journal of Geology and Mineral Resources) Journal of Geosciences and Applied Geology
Syaiful Alam
Fakultas Teknik Geologi, Universitas Padjadjaran
Chemistry Civil Engineering, Building, Construction & Architecture Earth & Planetary Sciences Energy Engineering Environmental Science

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Regresi Non-Linear pada Pemodelan Dekompaksi Syaiful Alam; . Nurdradjat; Budi Muljana; Djadjang Jedi Setiadi
Bulletin of Scientific Contribution: GEOLOGY Vol 17, No 1 (2019): Bulletin of Scientific Contribution GEOLOGY
Publisher : Fakultas Teknik Geologi Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (423.801 KB) | DOI: 10.24198/bsc geology.v17i1.20989

Abstract

AbstractDecompaction modeling is critical step in geohistory analysis. Decompaction modeling aims to obtain the thickness of stratigraphic unit before being compacted. Formulation of decompaction modeling requires initial porosity ( )  and coefficient of compaction (c). These two parameters are disentangled by porosity-depth relationship. Exponential model is used as the basis for knowing the relationship. Historically, exponential model often describes a more realistic porosity-depth phenomenon than other models. The exponential model yield the absence of negative porosity as the depth increases. The parameter  and c from a number of data are solved through regression method. This paper presents statistical explanation on non-linear regression to generate a simpler formulation, thus facilitating the calculation of initial porosity and coefficient of compaction. These parameters are used later in decompaction modeling.  Keywords: Decompaction modeling, non-linear regression, initial porosity, coefficient of compaction. AbstrakPemodelan dekompaksi adalah bagian yang penting dalam analisis geosejarah. Pemodelan dekompaksi bertujuan untuk mendapatkan ketebalan unit stratigrafi sebelum mengalami kompaksi. Formulasi pemodelan dekompaksi memerlukan parameter porositas awal ( ) dan koefisien kompaksi (c). Kedua parameter tersebut dapat ditentukan dari model porositas-kedalaman yang digunakan. Model eksponensial dijadikan sebagai landasan untuk mengetahui hubungan tersebut. Secara historis, model eksponensial seringkali menyajikan fenomena porositas-kedalaman yang lebih realistis dibandingkan dengan model lain. Model eksponensial memungkinkan tidak adanya nilai porositas yang negatif seiring dengan bertambahnya kedalaman. Parameter  dan c dari sejumlah data tersebut dapat dicari melalui metode regresi. Paper ini menyajikan pemaparan proses statistik regresi non-linear sehingga menghasilkan formulasi yang lebih sederhana. Formulasi ini memudahkan perhitungan penentuan parameter   dan c. Parameter tersebut digunakan nantinya dalam pemodelan dekompaksi. Kata kunci: Pemodelan dekompaksi, regresi non-linear, porositas awal, koefisien kompaksi.
Analisis Deret Waktu dalam Korelasi Stratigrafi: Studi Kasus Formasi Subang, Jawa Barat Syaiful Alam
Jurnal Geologi dan Sumberdaya Mineral Vol. 21 No. 4 (2020): JURNAL GEOLOGI DAN SUMBERDAYA MINERAL
Publisher : Pusat Survei Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.33332/jgsm.geologi.v21i4.502

Abstract

Fasies turbidit dan endapan hasil aliran gravitasi serta suksesi litologi yang monoton pada anggota batupasir Formasi Subang telah membuat korelasi stratigrafi menjadi sulit. Singkapan pada lokasi penelitian mayoritas berupa perselingan batupasir-batulempung, serta setempat ditemukan batupasir amalgamasi. Korelasi stratigrafi merupakan tahapan awal dalam analisis stratigrafi lebih lanjut, antara lain bertujuan untuk mengetahui runtutan kejadian sejarah pengendapan serta penyebarannya secara lateral. Analisis Time-Trend (TTA) merupakan metode dalam statistik untuk melihat tren/pola yang ada dari suatu sikuen data. TTA kemudian diterapkan pada penampang stratigrafi terukur pada anggota batupasir Formasi Subang yang tersingkap di lintasan Sungai Cikandung, Jawa Barat. Berdasarkan TTA, terdapat enam pola penumpukan strata yang dapat dikorelasikan secara meyakinkan, dengan batupasir amalgamasi sebagai variasi lokal dalam tren global yang melekat pada penampang stratigrafi di daerah penelitian.Katakunci: Analisis Time-Trend (TTA), korelasi stratigrafi, Formasi Subang.
Stratified Soil Characterization using 1D Resistivity Inversion along the Pasuruan Coastline, East Java Syaiful Alam; Nur Khoirullah; Yanwar Yusup Rukmana
Journal of Geological Sciences and Applied Geology Vol 2, No 5 (2018): 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.v2i5.20248

Abstract

The inversion has been widely used in subsurface modeling of numerousdata. The number of stratified soil layer and thicknesswere driven by damped least-squares inversion method.This studyintegrated five borehole logs and six vertical electrical sounding measurements. The inversion result is able to predict an unsampled of borehole data. The resulting maximum rms error is 0.22 and minimum rms error is 0.011 from 1D inversion.The borehole datas indicatedgravelly soil layer, sandy soil layer,and clayey soil layer withthe resistivity values respectively range from 33.6-7.45 (Ohm.m), 7.45-3.98 (Ohm.m), and 3.98-0.016 (Ohm.m).Based on the studyresult there were possibilities of seawater intrusion indication according to the soil stratigraphic profile based on resistivity properties and borehole data. Keyword: Pasuruan coastline, stratified soil, 1D resistivity inversion.
Stratigraphy and structural pattern of Kebumen Region using Second Vertical Derivative of Gravity Data, Central Java Syaiful Alam
Journal of Geological Sciences and Applied Geology Vol 4, No 1 (2020): 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.v4i1.29018

Abstract

Gravity forward modeling has been carried out in Kebumen Region, Central Java Province. With its position on the mélange complex, the geological complexity in this area is still a challenge to be modeled. Bougeur anomaly values in the study area ranged from 50 mGal to 130 mGal. The structural morphology of the Luk-Ulo Mélange Complex and Kulon Progo Mountain have higher Bougeur anomaly, ranging from 105 to 125 mGal. The residual positive anomaly zones in the northwest and southeast are situated with residual negative anomaly zones in between. The shallow effect through the Second Vertical Derivative method shows the patterns of fault types separating the two anomalous zones of Karangsambung and Kulon Progo region. The Luk Ulo Mélange Complex and stratigraphy of Karangsambung Formation up to Halang Formation are faulted by thrust-fault and strike-slip structural pattern. Keyword: Stratigraphy, structural pattern, second vertical derivative.
Evidence of Pliocene-Pleistocene Unconformity in eastern Bogor Trough, Sumedang-West Java Syaiful Alam; Yoga Andriana Sendjadja; Lia Jurnaliah; Kurnia Arfiansyah Fachrudin; Reza Mohammad Ganjar Gani
Journal of Geological Sciences and Applied Geology Vol 3, No 1 (2019): 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.v3i1.21528

Abstract

AbstractRecent measuring stratigraphic observation in Cikandung River has revealed the Late Pliocene stratigraphic and tectonic event. Research area is located in easter Bogor Trough. Previously, it was stated controversially pertaining to the stratigraphic relationship between Kaliwangu and Citalang Formations. The outcrop-based remark has never been explained, slightly intuitive. Making strike and dip measurements and stratigraphic analysis using tape and compass traverse were done to unveil the role of Plio-Pleistocene tectonic regime in stratigraphic-filling of the basin. Strike azimuths recorded from several locations of Citalang and Kaliwangu Formations show angular geometry and both of those sedimentary facies within formations indicate the significant and rapid change in depositional process. But interestingly, the angular geometry is only founded in the southern part of study area. To the north, angular relationship becomes parallel. This geometrical distribution implies the strong influence of tectonic regime in Late Pliocene interval. The evidence from outcrops observation conclude the unconformity between Citalang and Kaliwangu Formations. Keywords: Stratigraphic unconformity, Citalang and Kaliwangu Formations, Plio Pleistocene Tectonic
MOUNTAIN-FRONT SINUOSITY AND ASYMMETRICAL FACTOR OF LELES-GARUT INTRA-ARC BASIN, WEST JAVA Iyan Haryanto; Djadjang Jedi Setiadi; Syaiful Alam; Nisa Nurul Ilmi; Edy Sunardi
Journal of Geological Sciences and Applied Geology Vol 2, No 5 (2018): 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.v2i5.20230

Abstract

The Leles-Garut Basin, with an elevation ranges between 650 and 725 above mean sea level, is a Quaternary topographic basin area situated in the east-trending volcanic arc of West Java. In contrast to the adjacent Bandung Basin, the nature of the basin bounding area of the Leles-Garut Basin is not clearly defined. The presence of volcanic chain and structural lineament exhibits the difference in morphological features. A quantification of morphological indices was chosen to redefine an active tectonic involvement in surrounding basin border. Mountain-front sinuosity indices range from 1.1 to 3.9 and basin asymmetrical factor suggests a wide range of the effects of active tectonic even a little tilting. The study unveil that the basin bounding is not only volcano-bounded but also fault-bounded.
Co-Authors . Nurdradjat Budi Muljana Djadjang Jedi Setiadi Edy Sunardi Iyan Haryanto Kurnia Arfiansyah Fachrudin Lia Jurnaliah Nisa Nurul Ilmi Nur Khoirullah Reza Mohammad Ganjar Gani Yanwar Yusup Rukmana Yoga Andriana Sendjadja