Yan Rizal
Department of Geology, Institut Teknologi Bandung

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SEDIMENTARY FACIES AND HYDROCARBON RESERVOIR POTENTIAL OF SAND FLAT IN THE UPPER PART OF TAPAK FORMATION IN BANYUMAS AREA, CENTRAL JAVA Yan Rizal; Wahyu Dwijo Santoso; Alfend Rudyawan; Ricky Adrian Tampubolon; Affan Arif Nurfarhan
JURNAL RISET GEOLOGI DAN PERTAMBANGAN Vol 28, No 2 (2018)
Publisher : Indonesian Institute of Sciences

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (2392.507 KB) | DOI: 10.14203/risetgeotam2018.v28.835

Abstract

The upper part of Tapak Formation in Kali Cimande consists of alternating sandstones, siltstone and mudstone. The alternating sequence showed a fining and thinning upward bedding pattern. The facies association of the alternation built up by sand flat facies, which characterized by medium sandstone, moderate sorted, with cross-lamination sedimentary structures and mostly on the top of sandstone layer found a bioturbation trace fossils (Skolithos). Mixed flat facies, which is characterized by an alternation of thin layered sandstones with mudstone and siltstone, with lenticular, wavy, and flaser sedimentary structures, contained many forms of bioturbation, such Planolites, Thallasinoides, Lockeia, and Ophiomorpha. Mud flat facies association, is characterized by a repeated of claystone with thin sandstone intercalation, where the ratio of clay content more than 95 % of the total layers, contained abundantly with trace fossil Lockeia. Upper Tapak Formation plays as moderate reservoir potential. The thick sandstone in sand flat facies with moderate to poorly sorted and moderate porosity is required to provide hydrocarbon flows in Banyumas Basin.Bagian atas Formasi Tapak di Kali Cimande terdiri dari perselingan batupasir-batulanau dan mudstone. Sekuen perselingan menunjukkan pola perlapisan menghalus dan menipis ke atas. Asosiasi fasies tersebut terdiri dari fasies sand flat, yang dicirikan oleh batu pasir sedang, pemilahan sedang, struktur sedimen silang-siur serta fosil jejak bioturbasi (Skolithos) pada bagian puncak kebanyakan lapisan batu pasir. Fasies mixed flat, dicirikan oleh perselingan batupasir berlapis tipis dengan mudstone dan batulanau, serta struktur sedimen lentikular, perlapisan bergelombang, dan flaser, mengandung banyak bioturbasi, seperti Planolites, Thallasinoides, Lockeia, serta Ophiomorpha. Asosiasi Fasies sand flat, dicirikan oleh perulangan batulempung dengan sisipan batupasir tipis, dengan kandungan lempung lebih dari 95% total lapisan, serta fosil jejak Lockeia yang melimpah. Formasi Tapak Atas berperan sebagai reservoir potensial sedang. Bagian batupasir tebal di fasies sand flat dengan pemilahan sedang hingga buruk dan porositas sedang diperlukan untuk menyediakan aliran hidrokarbon di Cekungan Banyumas.  
PALEONTOLOGY OF ACROPORA CORALS AND STANDARD FACIES BELT FROM UJUNGGENTENG AREA, WEST JAVA Wahyu Dwijo Santoso; Yahdi Zaim; Yan Rizal
JURNAL RISET GEOLOGI DAN PERTAMBANGAN Vol 28, No 2 (2018)
Publisher : Indonesian Institute of Sciences

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1528.229 KB) | DOI: 10.14203/risetgeotam2018.v28.799

Abstract

The detail taxonomy analysis was performed to classify Acropora corals in Ujunggenteng Area. The research area was selected because the continuously exposed Quaternary coralline limestones, indicated the high variation and wide distribution of coral fossils. Moreover, the facies changes and contacts with shoreface sediments were clearly observed in this area. Detail taxonomy based on morphological description can classify Acropora corals in Ujunggenteng area into four species: Acropora cervicornis, Acropora palifera, Acropora gemmifera, and Acropora humilis. The study of coral paleontology and the application of the presence of corals as a standard facies belt were still rarely performed in Indonesia. Previous studies classified the coralline limestone into one standard facies belt, which was the organic build- up standard facies belt. Another approach was required to capture many conditions of coral fossil occurrences; not only in build-up condition but also in transported condition. Therefore, another purpose of this study is to modify the standard facies belt with a different approach using coral taphonomy and sediment association.Analisis taksonomi secara detil dilakukan untuk mengklasifikasikan koral Acropora di daerah Ujunggenteng. Daerah penelitian dipilih karena tersingkapnya batugamping terumbu berumur Kuarter yang menerus, yang menunjukkan tingginya jumlah spesies dan distribusi fosil koral yang luas. Selain itu, perubahan fasies dan kontak dengan batupasir pantai dapat jelas diamati pada daerah ini. Taksonomi detil berdasarkan deskripsi morfologi dapat mengelompokkan koral Acropora di daerah Ujunggenteng menjadi empat spesies: Acropora cervicornis, Acropora palifera, Acropora gemmifera, dan Acropora humilis. Selain itu, studi mengenai paleontologi dan penggunaan kehadiran koral sebagai dasar pembagian sabuk standar fasies batugamping masih jarang dilakukan di Indonesia. Studi sebelumnya mengelompokkan batugamping terumbu menjadi satu sabuk standar fasies, yaitu organic build up. Pendekatan yang lain diperlukan untuk menjelaskan kondisi koral lainnya pada batugamping, tidak hanya dalam kondisi tumbuh, tetapi juga dalam kondisi tertransportasi. Oleh karena itu, penelitian ini bertujuan untuk memodifikasi sabuk standar fasies dengan pendekatan berbeda menggunakan tafonomi koral dan asosiasi sedimen. 
First Evidence of Miocene Avian Tracks from Sumatra: Short Announcement Yahdi Zaim; Yan Rizal; Gregg F. Gunnell; Thomas A. Stidham; Russell L. Ciochon; Aswan Aswan
Berita Sedimentologi Vol 20, No 1 (2011)
Publisher : Ikatan Ahli Geologi Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (561.194 KB) | DOI: 10.51835/bsed.2011.20.1.214

Abstract

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The Palaeo-Kambaniru river mouth, Sumba, East Nusa Tenggara, Indonesia: A record of strongly seasonal catastrophic flow in a monsoon-controlled deltaic complex John-Paul Zonneveld; Yahdi Zaim; Yan Rizal; Aswan Aswan; Anne Fortuin; Roy Larick; Russell L. Ciochon
Berita Sedimentologi Vol 47, No 3 (2021)
Publisher : Ikatan Ahli Geologi Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1088.021 KB) | DOI: 10.51835/bsed.2021.47.3.360

Abstract

The Kambaniru River valley near the city of Waingapu preserves a thick succession of coarse-grained fluvial-deltaic sediment deposited during the Late Pleistocene. This succession incises through a thick uplifted coral reef terrace succession and records intervals of highly episodic flow events during the last glacial interval. The occurrence of intraclastic, coarse sand/gravel matrix olistostromes in several areas attests to the occasionally catastrophic nature of flow in the ancestral Kambaniru River. Small to moderate-sized coral-rich reefs and laterally restricted reef terraces occur on delta-front conglomerate successions at multiple horizons through the study interval. These reefs record both intervals of low flow as well as periodic river-mouth avulsion episodes. Comparison of radiometric dates obtained from pelecypod and coral material from both deltaic successions and laterally adjacent coral reef terrace intervals indicates that uplift/subsidence history of the terraces differs from that of the valley and that correlation between the two should be taken with care.
Sedimentary Facies of the Upper Part of Tapak Formation in Banyumas Area, Central Java Ricky Andrian Tampubolon; Yan Rizal
Berita Sedimentologi Vol 44, No 1 (2019)
Publisher : Ikatan Ahli Geologi Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1715.742 KB) | DOI: 10.51835/bsed.2019.44.1.64

Abstract

The upper part of Tapak Formation in Kali Cimande of Banyumas area shows a good example of tidal flat succession. The interval consists of alternating sandstones, siltstone and mudstone that show a fining and thinning upward bedding pattern and includes sand flat, mixed flat and mud flat sedimentary facies. The sand flat facies is characterized by medium-grained sandstone, moderately sorted, with cross-lamination sedimentary structures and bioturbation trace fossils (Skolithos) found mostly on the top of sandstone layer. The mixed flat facies is characterized by an alternation of thin layered sandstones with mudstone and siltstone, with lenticular, wavy, and flaser sedimentary structures. This facies contains many forms of bioturbations, such as Planolites, Thallasinoides, Lockeia, and Ophiomorpha. The mud flat facies is characterized by repeated claystone and thin sandstone intercalation, where the ratio of clay content being more than 95 % of the total layers, and contains abundant Lockeia trace fossil. The Upper Tapak Formation in Banyumas basin has moderate reservoir potential.
Fossil-bearing Citalang Formation, Sumedang-Majalengka, West Java Yan Rizal
Berita Sedimentologi Vol 47, No 3 (2021)
Publisher : Ikatan Ahli Geologi Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (333.46 KB) | DOI: 10.51835/bsed.2021.47.3.366

Abstract

The Citalang Formation in Sumedang-Majalengka area comprises of various lithological units, including coarse-grained sandstones to conglomerates, greenish grey to dark grey claystone with sandstone and tuff interbeds, and pumice-bearing tuffaceous sandstones and tuff. All these units occur in the lower part of the formation and the contacts with older, underlying rock units are unconformable in several places.Vertebrate fossil fragments are frequently found in the lowermost part of the formation, especially within the coarse-grained sandstones to conglomerates unit. This unit also holds stone tools artefacts, which were made from different kind of stones and show quite simple or primitive shape. The age of Citalang Formation is not yet resolved and still needs to be researched. Some published literatures suggest Pleistocene while there are others that suggest Pliocene.
Palaeontological surveys in Central Sumatra and Bangka Julien Louys; Yahdi Zaim; Yan Rizal; Gilbert J. Price; Aswan Aswan; Mika Rizki Puspaningrum; Holly Smith; Agus Tri Hascaryo
Berita Sedimentologi Vol 47, No 3 (2021)
Publisher : Ikatan Ahli Geologi Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (618.858 KB) | DOI: 10.51835/bsed.2021.47.3.358

Abstract

We report on results from surveys undertaken in Sumatra during 2018 and 2019. The surveys had three objectives: (1) to examine, sample, and record the extensive Quaternary fossil deposits from caves in West Sumatra; (2) determine the potential for fluvial deposits in Riau and Jambi provinces; and (3) relocate the fossil proboscidean remains reported from Bangka Island. Our surveys produced several significant results. We mapped three important Padang Highland caves, Ngalau Lida Ajer, Ngalau Sampit, and Ngalau Gupin, locating and sampling the main fossil deposits in each, as well as recording additional caves in the region. Our surveys of the fluvial systems in central-west Sumatra did not reveal any vertebrate Pleistocene deposits but did yield Mio-Pliocene trace fossils. Finally, we relocated elephant fossils from Bangka, but no in situ vertebrate remains could be found. These finds add important new data to the geological history of Sumatra.