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BULLETIN OF THE MARINE GEOLOGY
ISSN : 14106175     EISSN : 25278843     DOI : -
Core Subject : Science,
Bulletin of the Marine Geology is a scientific journal of Marine geoscience that is published periodically, twice a year (June and December). The publication identification could be recognized on the ISSN 1410-6175 (print) and e-ISSN: 2527-8843 (on-line) twice a year (June & December) and it has been accredited by Lembaga Ilmu Pengetahuan Indonesia (Indonesian Institute of Sciences) by Decree Number: 818/E/2015. As an open access journal, thus all content are freely available without any charge to the user. Users are allowed to download, and distribute the full texts of the articles without permission from the publisher.
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COASTAL CHARACTERISTICS OF PAPELA AND ADJACENT AREA, ROTE ISLAND, EAST NUSA TENGGARA Nineu Yayu Gerhanae; Udaya Kamiludin
BULLETIN OF THE MARINE GEOLOGY Vol 28, No 1 (2013)
Publisher : Marine Geological Institute of Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (692.173 KB) | DOI: 10.32693/bomg.28.1.2013.52

Abstract

Coastal typhology as data base that describes the result of interaction among geophysical element to geological elements and anthropogenic aspects. This data can provide any information of morphological development processes which is reflected in the coastal characteristics map. Identification of the Papela coastal area, Rote Island, about 60 km length, based on indirect and direct methods. Direct method is done by field observation such as : geological condition, relief, shoreline character and dominant process. While indirect method is done by imagery satellite interpretation and related previous data. Observation results of coastal condition, that the study area is divided into four coastal types, there are rocky cliff, sandy pocket beach, muddy and sandy beach. Coastal geology of study area composed of Holocene Alluvium, Quaternary Coral Limestone and Tertiary Bobonaro Complex that has low to high rocks resistance. Coastal morphology form by alluvium plain until slope rugged hills with low-high relief. The coastline characters consist of the rocky cliff, sandy pocket, sandy and muddy beach, with dominant process that influenced by fluviatil which is characterized by mangrove. Beach face material composed of sand and float stone, from 15-30 meters width with 5O-15O slope. Although the coastal area is relatively stable but erosion active process occurs at some places. It is characterized by float stone, and notches accompanied by rock fall. While, accretion occur in muddy coastal type that is characterized by mangrove plants. Key words : Coastal type, marine process, abrasion, accretion, Papela coast, Rote Island. Tipologi pantai sebagai data dasar yang menggambarkan hasil interaksi antara unsur geofisika terhadap unsur geologi dan aspek antropogenik. Data ini dapat memberikan informasi proses pembentukan morfologi yang tercermin di dalam peta karakteristik pantai. Identifikasi pesisir sepanjang lebih kurang 60 km di sekitar pantai Papela, Pulau Rote, Nusa Tenggara Timur menggunakan pendekatan metode langsung dan tidak langsung. Metode langsung dilakukan dengan pengamatan lapangan seperti kondisi geologi, relief, karakteristik garis pantai dan proses dominan. Sedangkan pendekatan tidak langsung melalui kajian citra satelit dan data terdahulu yang terkait. Hasil pengamatan kondisi pantai, bahwa daerah penelitian dibagi mejadi empat tipe pantai yaitu pantai bertebing batuan, berkantong pasir, berlumpur dan pantai berpasir. Geologi pantai daerah penelitian disusun oleh Alluvium Holosen, Batugamping Koral Kuarter dan Komplek Bobonaro Tersier yang mempunyai resistensi batuan rendah sampai tinggi. Morfologi pantainya berupa pedataran pantai alluvium sampai kaki/lereng perbukitan bertebing dengan relief rendah-tinggi. Karakter garis pantainya terdiri dari bertebing batuan, berkantong pasir, pantai berpasir, dan berlumpur dengan proses dominan yang dipengaruhi oleh fluviatil dicirikan oleh tumbuhan bakau. Paras muka pantai disusun oleh material pasir dan rataan batuan, memiliki lebar berkisar 50 meter dengan kemiringan datar-landai pada tipe pantai berpasir. Meskipun terjadi kesetimbangan pantai atau merupakan pantai yang relatif stabil tetapi di beberapa tempat proses abrasi tetap aktif. Hal ini dicirikan oleh adanya rataan batuan, dan takik-takik yang disertai oleh jatuhan batuan. Sebaliknya, sedimentasi terjadi pada tipe pantai berlumpur yang dicirikan oleh tumbuhan bakau. Kata kunci: Tipologi pantai, proses laut, abrasi, akrasi, dan pantai Papela
THE IMAGES OF SUBSURFACE TERTIARY – QUARTENARY DEPOSITS BASED ON GROUND PENETRATING RADAR RECORDS OF SUBI KECIL ISLAND COAST, NATUNA DISTRICT, RIAU ARCHIPELAGO PROVINCE Kris Budiono
BULLETIN OF THE MARINE GEOLOGY Vol 28, No 1 (2013)
Publisher : Marine Geological Institute of Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (2550.147 KB) | DOI: 10.32693/bomg.28.1.2013.53

Abstract

Subsurface Tertiary to Quaternary deposits from coast of Subi Kecil Island, Natuna Distric, Riau Archipelago Province, were imaged with Ground Penetrating Radar (GPR). The GPR survey was carried out by using GSSI Surveyor III/20 with 270 MHz and 40 MHz of 3200 MLF antennas. GPR data were processed using software GSSI’s RADAN for Windows NT™. The interpretation were done by using the radar facies as a groups of radar reflections. The GPR images of study area can be recoqnized in to several facies such as parallel, sub parallel, chaotic, oblique, mound and reflection-free. The calibration were done with geological data along the coast (cliff and outcrop). Unit A is the uppermost layer which is characterized by continous to non continous pararel reflection, srong reflector and high amplitude and is interpreted as alluvium deposits. Below the unit A is unit B which is characterized by non continous sub parallel, chaotic and mound reflector, strong reflector and high amplitude. Unit C and D (Mio-Oligocene) are overlain by unit A and B include chaotic, reflection-free and, locally, discontinuous parallel, oblique mound reflector radar facies, correlatable at the cliff face to massive sands, mostly representing near coastal deposits. These units are bounded by continuous, high amplitude reflections that can be easily correlatable throughout the GPR profiles, serving as important stratigraphic markers. The GPR survey may improve the reconstruction of the depositional environments through the recognition of massive and unconsolidated sand deposits within unit A and B (Holocene). The stratigraphic framework was also improved through the recognition of the discontinuity surface between Units C and D. Keywords: radar facies, stratigraphy, Tertiary to Quatenary, Subi Kecil Island Pencitraan endapan bawah permukaan Tersier sampai Kuarter di pantai Pulau Subi Kecil, Natuna, Propinsi Riau Kepulauan, telah dilakukan dengan “Ground Penetrating Radar (GPR). Survey GPR dilakukan menggunakan SIR 20 GSSI dengan antenna 200 MHz, 40 MHz da MLF 3200. Data GPR diproses mengunakan perangkat lunak Radan GSSI untuk Window NTTM. Citra Radar di daerah penelitian dapat dibagi menjadi reflektor paralel, sub paralel, chaotik, oblik, undulasi dan bebas refleksi. Kalibrasi telah dilakukan dengan kondisi geologi sepanjang pantai (tebing dan singkapan batuan). Unit A merupakan lapisan paling atas, dicirikan oleh reflektor parallel yang menerus dan tidak menerus, reflektor kuat, amplitudo tinggi dan ditafsirkan sebagai endapan alluvium. Di bawah unit A adalah unit B yang dicirikan oleh reflektor sub paralel yang menerus sampai tidak menerus, chaotic, hiperbolik, dengan reflektor kuat dan amplitudo tinggi. Unit C dan D (Mio-Oligosen) ditutupi oleh unit B yang dicirikan oleh fasies reflektor chaotic, bebas reflektor, dan secara lokal pararel tidak menerus, miring dan hiperbolik, dapat dikorelasikan dengan pasir padat pada tebing sebagai endapan dekat pantai. Citra GPR memperlihatkan rekonstruksi lingkungan pengendapan melalui pengenalan pasir padat dan pasir lepas pada unit A dan B (Holosen). Kerangka stratigrafi akan lebih baik melalui pengenalan ketidak menerusan lapisan antara unit C dan D. Kata kunci: fasies radar, stratigrafi, Tersier sampai Kuarter, Pulau Subi Kecil
CHARACTERISTIC OF SHALE GAS RESERVOIR USING LMR (LAMBDA-MU-RHO) INVERSION: CASE STUDY BARNETT SHALE, FORT WORTH BASIN TEXAS, USA Hagayudha Timotius; Yulinar Firdaus
BULLETIN OF THE MARINE GEOLOGY Vol 28, No 1 (2013)
Publisher : Marine Geological Institute of Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (879.105 KB) | DOI: 10.32693/bomg.28.1.2013.54

Abstract

The decreasing of fossil fuel reserves in the conventional reservoir has made geologists and geophysicists to explore alternative energy source that could answer energy needs in the future. Therefore the exploration of oil and gas that is still trapped in the source rock (shale) is needed, and one of them still developed in shale gas. The method of Amplitude Versus Offset (AVO) Inversion is used for Lambda-Mu-Rho attributes, that is expected to assess values of physical parameters of shale. Fort Worth Basin is chosen to be a study area because, the Barnett Shale Formation has proven contains of oil and gas. This study using synthetic seismic data, based on geological model and well log data obtained from Vermylen (2012). It is expected from the study of Barnett Shale that related to shale gas development could be applied. Keyword: Shale gas, Barnett Shale, Fort Worth Basin, AVO Inversion, Lambda-mu-rho attributes Penurunan cadangan bahan bakar fosil pada reservoar konvensional membuat ahli geologi dan geofisika mengeksplorasi sumber energi alternatif guna menjawab kebutuhan energi di masa depan. Oleh karena itu dibutuhkan eksplorasi minyak dan gas yang masih terperangkap dalam batuan induk (serpih), dan salah satunya yang dikembangkan saat ini adalah “shale gas”. Penggunaan metode inversi Amplitudo Versus Offset (AVO) untuk atribut Lambda-Mu-Rho diharapkan dapat menghasilkan nilai-nilai parameter “fisis shale”. Cekungan Fort Worth dipilih sebagai lokasi penelitian ini karena terdapat Formasi “Barnett Shale” yang telah terbukti mengandung minyak dan gas. Penelitian ini menggunakan data seismik sintetik berdasarkan model geologi serta data sumur yang diperoleh dari Vermylen (2012). Diharapkan dari penelitian tentang Barnett Shale yang berkaitan dengan pengembangan shale gas dapat diaplikasikan. Kata kunci: “Shale gas”, “Barnett Shale”, Cekungan Fort Worth, Inversi AVO, atribut Lambda-Mu-Rho
INDICATION OF GOLD AND SILVER OCCURRENCE AT SAMPIT BAY, KOTA WARINGIN TIMUR DISTRICT, CENTRAL KALIMANTAN PROVINCE I Wayan Lugra; Udaya Kamiludin
BULLETIN OF THE MARINE GEOLOGY Vol 28, No 1 (2013)
Publisher : Marine Geological Institute of Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (830.816 KB) | DOI: 10.32693/bomg.28.1.2013.50

Abstract

The study area is fluviatile deposit which consists of yellow to light gray loose sand, iron oxide, and kaoline spreading from the land shallowing to sea direction. Concentration grade for determining of gold and silver content used a total analysis of the hot mixture HF-HNO3-HClO4 with measurements "Atomic Absorption Spectrofotometry".(AAS). Highest concentration of gold and silver found at sample GCTS-31 that gold 0.096 ppm and silver 2.284 ppm, in muddy sand type sediment, at 3.1 meters depth and arround 1,250 meter length from coast line. While the lowest concentration of the gold was 0.025 ppm found at sample GBTS 14 in very fine sand type sediment located at 1.07 meter depth and approximately 320 meters length from coast line. The lowest concentration of the silver was founded at sample GBTS 25 that is 0.860 ppm in sandy mud sediment type located at 2.49 meters depth and approximately 3,000 meters length from the coast line. The gold placer is may derived from weathering of Pambuang Formation which spreads in the west and north of Sampit Bay, and transported by Mentaya River and longshore current system. Key word : sediment samples, laboratory analyses, gold, silver and Sampit Bay. Daerah penelitian merupakan endapan fluviatil terdiri dari pasir lepas berwarna kuning muda sampai abu-abu pucat, oksida besi, dan kaolin yang memiliki sebaran makin mendangkal ke arah laut. Kadar konsentrasi untuk menentukan kandungan emas dan perak menggunakan analisis total campuran HF-HNO3-HClO4 dengan metoda AAS. Analisa besar butir digunakan untuk memisahkan sedimen fraksi kasar sedangkan analisa pipet dilakukan terhadap sediment fraksi halus. Kadar emas dan perak tertinggi terdapat pada contoh GCTS -31, yaitu emas 0,096 ppm dan perak 2,284 ppm, pada jenis sedimen lumpur pasiran, di kedalaman 3,1 meter dan sekitar 1.250 meter dari garis pantai. Sedangkan kadar emas terendah yaitu 0,025 ppm terdapat pada contoh GBTS 14 pada jenis sedimen pasir sangat halus di kedalaman 1,07 meter dan sekitar 320 meter dari garis pantai. Kadar perak terendah dijumpai pada contoh GBTS 25 yaitu 0,860 ppm dengan jenis sedimen pasir lumpuran pada kedalaman 2,49 meter dan sekitar 3.000 meter dari garis pantai. Sumber emas plaser diperkirakan dari lapukan Formasi Pembuang yang memiliki sebaran cukup luas di sebelah barat dan utara Teluk Sampit dan ditransportasi oleh Sungai Mentaya dengan anak-anak sungainya, serta sistem arus memanjang pantai. Kata kunci : contoh sedimen, analisis laboratorium, emas, perak dan Perairan Teluk Sampit.
THE PETROLOGY CHARACTERISTIC OF GRANITOID ROCK BASED ON GEOCHEMICAL ANALYSIS OF BAJAU CAPE COAST AND ITS SURROUNDING, WEST KALIMANTAN Noor C.D. Aryanto; E. Suparka
BULLETIN OF THE MARINE GEOLOGY Vol 28, No 1 (2013)
Publisher : Marine Geological Institute of Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (938.017 KB) | DOI: 10.32693/bomg.28.1.2013.51

Abstract

The aim of this study is to identify of petrology characteristic based on geochemical analysis in order to know the granitoid rock type. Administratively, the study area is in the City and District of Singkawang, West Kalimantan Province, at coordinate 108°48'30” - 109°1'30” E and 0°40'30” - 0°54'30” N and, situated ± 145 km to the north of Pontianak City. The outcrop of granitoid along Bajau Cape coast and its surrounding, had been analyzed petrographically and geochemically using AAS method. Based on analysis of five samples show that the ratio mole of Al2O3/(CaO+Na2O +K2O) > 1 ranged between 1.12 and 1.7, while the rest of three samples are moderately aluminous, with a ratio value between 0.5 and 1.0. The ratio between K2O and (K2O+Na2O+CaO) ranges 0.07 to 0.55 (moderate) that forms alkali feldspar normative ranges from 3.8 to 15.89 wt%. This ratio shows that granite alkali feldspar is classified to be calc-alkaline series. Petrographically, this rock is porfiritic texture, hollocrystalline, granular hypodiomorphic and biotite present as phenocryst, yellowish brown, euhedral, thin and platy. The content of oxides element (Na2O and MgO) tend to decrease, whereas of other oxides elements, namely Al2O3, TiO2, K2O, FeO and CaO increased, parallel with the raising of SiO2. Therefore, the Singkawang Granitoid can be grouped as alkali feldspar granite, syeno-granite and quartz monzonite. Keywords: petrography, geochemstry, major elements, calc-alcaline affinity, granitoid type and Bajau Coast, West Kalimantan. Penelitian ini bertujuan untuk mengidentifikasi karakteristik petrologi, berdasarkan analisa geokimia sehingga jenis batuan granitoidnya dikenali. Secara administratif, daerah penelitian termasuk ke dalam Kota dan Kabupaten Singkawang, Provinsi Kalimantan Barat, pada koordinat 108°48'30” - 109°1'30” BT and 0°40'30” - 0°54'30” LU dan terletak ± 145 km, arah utara dari Kota Pontianak. Singkapan batuan granitoid sepanjang pantai Tanjung Bajau dan sekitarnya telah dianalisis secara petrografi dan geokimia dengan menggunakan AAS. Berdasarkan 5 contoh yang dianalisa menunjukan perbandingan mol Al2O3/(CaO+Na2O +K2O) > 1, yakni berkisar antara 1,12-1,7, sedangkan 3 contoh sisanya bersifat peraluminus sedang, dengan nilai ratio antara 0.5-1.0. Perbandingan antara K2O dan (K2O+Na2O+CaO) berkisar antara 0,07-0,55 (sedang) yang membentuk alkali normatif feldspar berkisar 3,84 – 15,89% (berat). Perbandingan tersebut menunjukan batuan Granit alkali feldspar yang tergolong dalam seri batuan kalk-alkali. Secara petrografi, batuan tersebut menunjukkan tekstur porfiritik, holokristalin, hipidiomorfik granular dengan biotit hadir sebagai fenokris, coklat kekuningan, euhedral, pipih dan sedikit berlembar. Kandungan unsur oksida (Na2O dan MgO) cenderung mengalami penurunan, sedangkan unsur oksida lainnya, yaitu Al2O3, TiO2, K2O, FeO dan CaO mengalami kenaikan sejalan dengan makin bertambahnya SiO2. Maka dengan demikian Granitoid Singkawang dapat dikelompokan menjadi granit alkali feldspar, syenit-granit dan kuarsa-monsonit. Kata kunci: Petrografi, geokimia, senyawa utama, afinitas kalk-alkalin, batuan granitoid dan Pantai Bajau, Kalimantan Barat.

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