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DESKRIPSI LITOLOGI BATUAN DASAR DAN HUBUNGANNYA DENGAN KARAKTERISTIK RESERVOIR REKAHAN ALAMI DI BLOK OGAN KOMERING, CEKUNGAN SUMATRA SELATAN Fitriana, Bayu Sapta; Sapiie, Benyamin; Rudyawan, Alfend
Bulletin of Geology Vol 7 No 3 (2023): Bulletin of Geology
Publisher : Fakultas Ilmu dan Teknologi Kebumian (FITB), Institut Teknologi Bandung (ITB)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/bull.geol.2023.7.3.3

Abstract

Keberadaan hidrokarbon pada reservoir batuan dasar (basement) di Blok Ogan Komering (OK), Sumatra Selatan, telah terbukti sejak tahun 1992 sejak penemuan hidrokarbon pertama pada sumur ASD-1 dengan laju alir 1.890 BOPD. Pada Tahun 2014, hidrokarbon pada batuan dasar kembali ditemukan dari pemboran sumur BDA-1 dengan laju alir 3,4 MMSCFD. Temuan-temuan hidrokarbon pada batuan dasar ini memberikan indikasi yang penting untuk menemukan kembali potensi-potensi hidrokarbon dari reservoir batuan dasar di daerah ini. Fokus penelitian ini memuat aspek litologi, umur batuan, dan karakteristik rekahan alamiberdasarkan data sumur, seismik, petrografi dan data pentarikhan umur batuan (age dating) yang memberikan wawasan tentang litologi batuan dasar, serta hubungannya dengan karakteristik rekahan alami dan kualitas reservoir di Blok OK, Cekungan Sumatra Selatan. Penemuan hidrokarbon di reservoir Batuan dasar pra-Tersier di area Blok OK sebelumnya didefinisikan terakumulasi pada batuan dasar granitik. Berbagai litologi yang terdapat di batuan dasar menunjukkan kompleksitas dari sejarah tektonik di Cekungan Sumatera Selatan. Studi petrografi lebih rinci menunjukkan komposisi litologi yang lebih kompleks. Litologi batuan dasar pra-Tersier terdiri dari granodiorit, diorit, marmer, andesit, serpih, filit dan sekis. Pentarikhan K-Ar pada batuan dasar andesitmenghasilkan interval umur antara 61-131 juta tahun yang lalu, setara dengan Kapur Awal-Akhir. Secara lebih detail, batuan beku di daerah ini telah mengalami proses alterasi hidrotermal, yang ditunjukkan dengan kehadiran mineral-mineral alterasi dalam komposisi batuannya. Log gambar pada interval batuan dasar menunjukkan perkembangan rekahan alami yang baik pada interval batuan dasar. Perkembangan rekahan alami memiliki korelasi dengan jenis litologi. Rekahan alami berkembang dengan baik pada litologi granodiorit, diorit, marmer, dan kuarsit. Batas satuan antar litologi yang beragam ini diinterpretasikan sebagai kontak sesar. Kontak sesar yang disertai dengan zona hancuran antara litologi yang berbeda menguntungkan untuk pengembangan rekahan dan berkorelasidengan indikasi hidrokarbon. Kata Kunci: Batuan dasar, petrografi, rekahan, reservoir, Sumatra Selatan
The uplift rate of Sulawesi East Arm and the activity of Batui Fault using a tectonic geomorphology approach in the Luwuk Area, Sulawesi Hikmy, Isbram Ginanjar; Rudyawan, Alfend; Putri, Berta Syafira; Sapiie, Benyamin; Gunawan, Indra
Jurnal Geologi dan Sumberdaya Mineral Vol. 26 No. 1 (2025): JURNAL GEOLOGI DAN SUMBERDAYA MINERAL
Publisher : Pusat Survei Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.33332/jgsm.geologi.v26i1.663

Abstract

Sulawesi is a tectonically active area with convergent triple-junction amidst Eurasian, Indo-Australian and Pacific Plate. The study area is located in the suture zone of sedimentary Banggai-Sula Microcontinent and East Sulawesi Ophiolite. This research is aimed to determine fault activity and rate of tectonic uplift of Luwuk mountainous area. Field geological mapping had been done to determine lithology and geological structure along with morphometric analysis to measure definitive result of tectonic activities. Geological structure features which encountered in this area are Batui Thrust, Pasini Thrust, Lobu Balongan Fault Zone, and Lambangan Anticline. The sedimentary rocks have average N315oE dip direction with angle of 41o. Based on tectonic geomorphology and morphometric analyses are resulting the most active tectonic areas passed by the Batui and Pasini Thrust which have NE-SW direction and Lobu Balolang Fault Zone relative to others. The Batui Thrust is considered as active fault intersected the East Sulawesi Ophiolite and Banggai-Sula Microcontinent which segmented with wrench faults. Number of thrust faults parallel to the Batui Thrust generate Batui Thrust Belt which propagate from the ultramafic rocks to the sedimentary rocks within the suture zone. As a result, the presence of active fault is uplifting the East Arm of Sulawesi with 0.408 ± 0.008 mm and 0.213 ± 0.046 mm uplift rate per year by the presence of high altitude Celebes Molasses. These rates are getting higher to the west. Keywords: Batui Thrust, East Sulawesi Ophiolite, Luwuk, morphometry, tectonic geomorphology, uplift rate
STRUCTURAL CONTROL RELATED WITH MEDIUM-TO-VERY HIGH Au GRADE AT PIT B EAST AND B WEST, TUJUH BUKIT MINE, EAST JAVA Dermawan, Ilham Aji; Subandrio, Andri Slamet; Rudyawan, Alfend; Sanjaya, Arya Dwi; Maharief, Rama; Anditya, Krisma; Hasnur, Rizfan; Muttaqien, Muchamad Satya; Fitri, Cicih Larasati Widya; Pahlevi, Andi; Daulay, Dedy; Purwanto, Agus; Sjoekri, Adi Adriansyah
Bulletin of Geology Vol 4 No 1 (2020): Bulletin of Geology
Publisher : Fakultas Ilmu dan Teknologi Kebumian (FITB), Institut Teknologi Bandung (ITB)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/bull.geol.2020.4.1.2

Abstract

Tujuh Bukit secara umum disusun oleh batuan vulkanik dan vulkaniklastik Formasi Batuampar berumur Oligosen Akhir sampai Miosen Tengah. Setelah terjadi aktivitas tektonomagmatisme pada Pliosen, satuan tersebut teralterasi dan menjadi host rock bagi mineralisasi ekonomis yang juga terbentuk pada Pliosen.Daerah penelitian berada di tambang terbuka Pit B Eastdan B West. Kavling yang mencakup kedua pit tersebut memiliki luas ± 700 x 500 m2, terletak pada koordinat ± 9045100 –9045600 mU dan ± 174400 –175100 mT sistem proyeksi koordinat UTM WGS 1984 zona 50S. Penelitian ini membahas tentang kontrol struktur yang berperan dalam pembentukan karakteristik alterasi dan mineralisasi Au sistem epitermal sulfidasi tinggi yang berkembang di Pit B East dan B West, tambang Tujuh Bukit. Struktur geologi yang dominan berkembang berupa sistem sesar mendatar berumur Pliosen, berarah relatif NW-SE dan N-S, dengan arah tegasan utama NNW-SSE mengikuti model pure shear. Terdapat pula sesar normal berarah relatif NW-SE dan sesar naik berarah relatif ENE-WSW. Sesar-sesar tersebut pada skala regional merupakan kompensasi akibat gaya tektonik tekanan (compressive) berarah NNW-SSE dalam satu periode tektonik yang sama. Sistem sesar mendatar menghasilkan zona-zona sesar normal dan zona tinggian pada geometri releasing stepover, releasing bend, dan restraining bend. Sesar-sesar mendatar yang ada di Pit B East dan B West merupakan sistem sesar strike-slippaling kecil pada skala regional Tujuh Bukit. Struktur geologi yang berkembang merepresentasikan tektonik Pulau Jawa saat ini.Terdapat lima satuan alterasi setelah dilakukan integrasi data lapangan, data pengeboran, dan hasil pemindaian ASD, yaitu: satuan kuarsa, kuarsa-alunit, kuarsakaolinit, kaolinit-montmorilonit-klorit, dan kaolinit-montmorilonit.Mineral bijih yang ditemukan berdasarkan observasi di lapangan dan pengamatan mineragrafi berupa pirit, kalkopirit, kovelit, bornit, tetrahedrit, azurit, malakit, hematit, dan goetit. Mineral-mineral tersebut umumnya ditemukan berasosiasi dengan alterasi yang mengalami silisifikasi, seperti satuan kuarsa, kuarsa-alunit, dan kuarsa-kaolinit.Alterasi silisifikasi dan mineralisasi Au kadar menengah hingga sangat tinggi umumnya berada pada zona-zona sesar normal yang diakibatkan oleh pergerakan sesar mendatar pada geometri releasing bend (daerah di sepanjang belokan Sesar BE 2 dan Sesar BE 3) dan releasing stepover (daerah di antara Sesar BE 1-BE2, di antara Sesar BW 2-BW3, dan di antara sesar BW 6-BW 7-BW 8), serta sesar normal yang sejajar dengan arah tegasan utamanya pada skala regional. Kata kunci: Sistem sesar mendatar, mineralisasi, epitermal sulfidasi tinggi, Tujuh Bukit
KARAKTERISTIK REKAHAN ALAMI, STUDI KASUS MODEL SINGKAPAN DIGITAL (DOM) BATUAN GRANITIK DI MUARO SILOKEK, SUMATERA BARAT Koesmawardani, Wildan Tri; Nurshal, M.E. Marshal; Sapiie, Benyamin; Rudyawan, Alfend
Bulletin of Geology Vol 3 No 3 (2019): Bulletin of Geology
Publisher : Fakultas Ilmu dan Teknologi Kebumian (FITB), Institut Teknologi Bandung (ITB)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/bull.geol.2019.3.3.1

Abstract

Digital Outcrop Model (DOM) is a method of building a more realistic, 3D-based geocellular model based on photogrammetric data. DOM can describe position of fractures with a minimum length of four meters, so it can describe better distribution and fracture geometry with more precision. DOM used has a dimension of 320 m × 12 m at fractured granitic rock outcrops at Muaro Silokek, West Sumatra. There are 1183 fracture interpretations in the DOM. Based on the fracture orientation scattered in the DOM, there are four segmentation structures with three domain orientation directions, north north west - south southeast (NNE-SSW), northeast - southwest (NE-SW), and east-northeast - west southwest (ENE-WSW). The results of kinematic analysis of the structural data show that the Muaro Silokek area is affected by the strike slip fault with the northwest-southeast direction (NW_SE) which is parallel with orientation of the Takung Fault. Fracture density analysis in DOM was carried out by grid method with grid dimensions of 20 m × 20 m resulting in a value range of 0.15 - 1 fracture/m2. From the results of the fracture density analysis, the kinematic analysis can be carried out to determine the minor fault orientation. Fracture density is strongly influenced by the distance to fault and has logarithmic distribution data with a high correlation coefficient R2 = 0.98.
New Insights into the Geological Evolution of Eastern Indonesia from Recent Research Projects by the SE Asia Research Group Watkinson, Ian M.; Hall, Robert; Cottam, Mike A.; Sevastjanova, Inga; Suggate, Simon; Gunawan, Indra; Pownall, Jonathan M.; Hennig, Juliane; Ferdian, Farid; Gold, David; Zimmermann, Sebastian; Rudyawan, Alfend; Advocaat, Eldert
Berita Sedimentologi Vol 23, No 1 (2012)
Publisher : Ikatan Ahli Geologi Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1328.003 KB) | DOI: 10.51835/bsed.2012.23.1.189

Abstract

Eastern Indonesia has a prolonged, complex tectonic history. It is where the Eurasian, Indo-Australian, Caroline and Philippine Sea plates converge, and where processes such as subduction, obduction, slab rollback, rifting, supracrustal extension, lower crustal flow and exhumation are very young or still active.For these reasons, the SE Asia Research Group (SEARG) at Royal Holloway, University of London, has made Eastern Indonesia one of its major research themes in recent years. The SEARG has been conducting geological research in SE Asia since 1982. Work has been undertaken in Indonesia, Malaysia, Thailand, the Philippines, Vietnam and the South China Sea. In 2012 the SEARG is directed by Professor Robert Hall, and involves 12 postgraduate students, 2 postdoctoral researchers, a large number of academic staff, research associates and collaborators in the UK and overseas. The group is funded by a consortium of oil companies.Here we summarise recent and ongoing SEARG projects in Eastern Indonesia. Most of the projects are field-based, but they all also employ new data and techniques, such as 40Ar-39Ar, U-Pb dating (SHRIMP and LA-ICP-MS), Hf isotope dating (LA-MC-ICP-MS), UTh/ He dating, multibeam bathymetry, high quality seismic and remote sensing data.
Bahasa Inggris: GEOLOGI DAN STUDI KONTROL STRUKTUR TERHADAP MINERALISASI DI DAERAH ARINEM, GARUT, JAWA BARAT Rudyawan, Alfend; Sujatmoko, Muhammad Lugas; Rizal, Yan
Buletin Sumber Daya Geologi Vol 20 No 1 (2025): Buletin Sumber Daya Geologi
Publisher : Pusat Sumber Daya Mineral Batubara dan Panas Bumi

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.47599/bsdg.v20i1.518

Abstract

Exploration by PT Aneka Tambang in 1981 identified several promising mineral prospects in West Java, categorized as low- to high-sulfidation epithermal types. One such prospect is the Arinem area in Garut, which became the focus of this study. Spanning 0.46 km², this area is located 45 km from Garut city. The data used in this research include field data and core samples from seven boreholes provided by PT ANTAM Tbk. This study aims to understand the geological and hydrothermal alteration processes of the region using field work measurements, petrographic, mineralographic, and ASD specTERRA The study area consists of volcanic and volcaniclastic units, intruded by Pyroxene Andesite and Hornblende Andesite, with prominent hydrothermal alteration zones. The geological structures include the Left-Lateral Arinem Fault and the Right-Normal Arinem Fault, both of which control hydrothermal processes. Minerals such as pyrite, chalcopyrite, galena, and sphalerite were identified, with mineral veins trending north – south. The results suggest that Arinem is a part of an en-echelon structure arrays part of a larger left lateral strike slip system in West Java that cross-cut by the younger NE – SW dextral faults. This provides crucial insight into the geology, subsurface alteration and mineralization distribution, highlighting its significance for ongoing exploration efforts.
Fault Surface Rupture Modeling Using Particle Image Velocimetry Analysis of Analog Sandbox Model Furqan, Terry Alfa; Sapiie, Benyamin; Natawidjaja, Danny Hilman; Widodo, Lilik Eko; Rudyawan, Alfend; Hadiana, Meli
Journal of Engineering and Technological Sciences Vol. 56 No. 1 (2024)
Publisher : Directorate 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.2024.56.1.10

Abstract

This study investigated the correlation between fault kinematics, surficial displacement, and surface rupture geometry patterns between earthquake cycles using particle image velocimetry (PIV) analysis of an analogue sandbox modeling that mimics InSAR observations. The research explored various fault systems, including reverse, normal, and strike-slip faults, through controlled sandbox experiments. The fault surface rupture zone manifests itself due to strain accumulation between two mobile blocks. The displacement magnitude is most pronounced on the surface and is absorbed by the section above the hanging wall or moving block. During fault surface rupture formation, the leading edge of the surface movement consistently extends beyond the anticipated fault surface rupture zone and retreats upon full fault surface rupture development. Subsequently, the distribution of the surface movement is sharply confined by the established fault surface rupture. The key findings of this study underscore the potential of PIV of sandbox modeling for studying fault surface rupture geometry and its development, providing insight into seismic processes. Overall, this work contributes to advancing our knowledge of seismic phenomena and improving strategies for earthquake prediction and mitigation.