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BULLETIN OF THE MARINE GEOLOGY

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Published by Marine Geological Institute of Indonesia

ISSN : 14106175 EISSN : 25278843 DOI : -

Core Subject : Science,

Earth & Planetary Sciences

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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Articles 173 Documents

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SUBMARINE LANDSLIDE AND LOCALIZED TSUNAMI POTENTIALITY OF MENTAWAI BASIN, SUMATRA, INDONESIA Haryadi Permana; C. Singh
BULLETIN OF THE MARINE GEOLOGY Vol 23, No 1 (2008)
Publisher : Marine Geological Institute of Indonesia

The new bathymetry and seismic data were acquired during the PreTI-Gap marine survey (February 15 to March 6, 2008). The survey was carried out along the NE margin of Mentawai Island using multi-beam swath bathymetry equipment, and 28-channels seismic streamer and four-airgun source. The first target was the Mega Island region near the epicenter of the 2007 great earthquake. The shallow bathymetry is characterized as a flat coral platform suggesting that 200 km elongated plateau is slowly subsiding without any active faults. Further north, from South Pagai to North of Siberut Islands, the seafloor morphology changes significantly. The deep and wide canyons or valleys produce very rough seafloor morphology between 50 and 1100 m water. In general, the submarine topography shows two break slopes at different depths. Between slope breaks, the undulating, hilly and circular features dominate, possibly caused by landslides. A push-up ridge is observed that dams the sediments eroded within a steep slope northeastward side. The seismic reflection data acquired along 14 dip seismic lines at the NE flank of Mentawai Islands, from Siberut to the South of Pagai Islands. We observed a set of southwestward dipping back thrust bounding the NE margin of the Mentawai Island. Keywords: submarine landslide, tsunami, Mentawai basin, Sumatra. Data batimetri dan seismik baru telah dihasilkan selama survey kelautan PreTi-Gap (15 Februari hingga 6 Maret 2008). Survei dilaksanakan sepanjang tepian timurlaut P. Mentawai menggunakan peralatan multibeam, seismic saluran ganda 28 kanal dengan sumber energi airgun. Sasaran pertama adalah memetakan kawasan pulau dekat pusat gempa tahun 2007. Kenampakan batimetri dangkal dicirikan dengan adanya dataran terumbu karang yang secara perlahan mengalami penurunan tanpa aktifitas sesar. Lebih jauh ke Utar, dari Pagai Selatan ke utara P. Siberut, morfologi dasar laut memperlihatkan perubahan secara signifikan, dimana lembah dasar laut memiliki lebar dan beda kedalaman antara 50 hingga 1100 meter. Secara umum, topografi dasar laut memperlihatkan dua kemiringan pada kedalaman yang berbeda dengan dicirikan adanya kenampakan perlipatan, perbukitan dan bentuk yang melingkar diperkirakan sebagai hasil gelinciran. Sebanyak 14 line data seismik refleksi pada sayap bagian timurlaut P. Mentawai, dari Siberut hingga ke selatan P. Pagai memperlihatkan adanya bukti sesar naik yang miring ke arah baratdaya yang masih satu set dengan tepian timurlaut P. Mentawai. Kata kunci: longsoran bawah laut, tsunami, Cekungan Mentawai, Sumatra.

Estimation of Sea Current Energy Potential by Using Calculation Models of Horizontal Axis Current Turbine in Toyapakeh Strait, Nusa Penida, Bali Beben Rachmat; Delyuzar Ilahude
BULLETIN OF THE MARINE GEOLOGY Vol 32, No 2 (2017)
Publisher : Marine Geological Institute of Indonesia

Toyapakeh Strait has a fairly strong ocean current velocity with a velocity between 0.5 m/s – 3.2 m/s. The duration of the strong current (V> 0.5 m/s) ranges from 13-22 hours per day. The location of the strong current occurrence is located to the east of Nusa Lembongan Island, precisely at the stationary current measurement location. Vertical distribution of the direction and velocity currents at this location are not uniform from the top to the bottom, especially in the water column depths of 2 m, 4 m and 6 m, whereas at the water column depths of 8 m to 16 m are relatively uniform. Calculation results of potential electrical power by using the horizontal axis turbine model with a capacity of 35.9 kW (Rite Verdan), 100 kW (Tocardo DD702HT) and 250 kW (Tocardo DD1001HT) show that all of the values have the optimal electric powers, especially during the spring tide, whereas during the neap tide only the turbine with a capacity of 35.9 kW can retrieved an optimal electrical power. Calculation result of the electric power potential by using the method of calculation performed by the Electric Power Research Institute Inc. at the point of measurement, indicated that the total amount of energy 42.5 MWh per month for the turbine model Tocardo DD1001HT, 17.27 MWh per month for turbine model DD702HT Tocardo, and 9.08 MWh per month for the turbine model Rite Verdan.Keywords: Toyapakeh Strait, current velocity, time duration, electric power, depth of the water column Perairan Selat Toyapakeh mempunyai kecepatan arus laut yang cukup kuat dengan kecepatan berkisar antara 0,5 m/det – 3,2 m/det. Durasi terjadinya arus kuat (V>0,5 m/det) berkisar 13 – 22 jam per hari. Lokasi tempat terjadinya arus kuat terletak di sebelah timur Pulau Nusa Lembongan, tepatnya di lokasi tempat pengukuran arus stasioner. Secara vertikal distribusi arah dan kecepatan arus di lokasi ini tidak seragam dari atas ke bawah, terutama pada kedalaman kolom air 2 m, 4 m dan 6 m, sedangkan untuk kedalaman kolom air 8 m sampai 16 m relatif seragam. Hasil perhitungan potensi daya listrik dengan menggunakan model turbin sumbu horisontal dengan kapasitas 35,9 kW (Rite Verdan), 100 kW (Tocardo DD702HT) dan 250 kW (Tocardo DD1001HT) diperoleh daya listrik yang cukup optimal terutama saat spring tide, sedangkan saat neap tide hanya turbin dengan kapasitas 35,9 kW yang masih menghasilkan daya listrik secara optimal. Hasil perhitungan potensi daya listrik dengan menggunakan metode perhitungan yang digunakan oleh Electric Power Research Institute Inc. di titik pengukuran diperoleh total energi yang dihasilkan dari model turbin Tocardo DD1001HT adalah sebesar 42,5 MWh per bulan, model turbin Tocardo DD702HT adalah sebesar 17,27 MWh per bulan, dan model turbin Rite Verdan adalah sebesar 9,08 MWh per bulan.Kata Kunci : Selat Toyapakeh, kecepatan arus, durasi waktu, daya listrik, kedalaman kolom air

THE SAFETY FACTOR ANALYSIS OF THE MARINE SLOPE STABILITY MODEL ON THE ACCESS CHANNEL OF MARINE CENTRE PLAN CIREBON, WEST JAVA. Franto Novico; Nur Adi Kristanto
BULLETIN OF THE MARINE GEOLOGY Vol 25, No 2 (2010)
Publisher : Marine Geological Institute of Indonesia

This study is focused on access channel model that safety factors of some slopes stability would be investigated. Plaxis version 8 is applied to analyze a magnitude of safety factors and displacements based on three different slopes of access channel there are 30Â°, 45Â° and 60Â°. Furthermore, parameters are adopted from geotechnical drilling and laboratory tests. A finite element is applied as a simple model to analyze within a Mohr-coulomb equation. Based on soil data analyses on Marine Center Plan, indicates low safety factor and high deformation. As results, 10 to 40 meters deformation of the slopes and 0.80 to 2.34 of safety factor are obtained of the models. For that reason, a combination between slope channel and infrastructure must be considered. Keywords: Safety factor, slope stability, access channel, Marine centre, Plaxis Kajian ini dilakukan terhadap faktor keamanan dari beberapa jenis kemiringan dinding alur pelayaran yang selanjutnya dilakukan pemodelan dengan menggunakan alur pelayaran Besarnya keruntuhan dan faktor keamanan pada beberapa sudut kemiringan yang berbeda telah dianalisis dengan menggunakan perangkat lunak geoteknik Plaxis Versi 8. Tiga jenis kemiringan yang berbeda telah dibuat yaitu sudut kemiringan 30Â°, 45Â° dan 60Â°. Sebagai data masukan, parameter diambil berdasarkan hasil pemboran geoteknik yang telah dianalisis di laboratorium. Model sederhana elemen terbatas telah dibuat dan dianalisis berdasarkan persamaan Mohr-Coulumb. Berdasarkan analisis data tanah pada rencana Marine Centre menunjukan faktor keamanan yang rendah dan deformasi yang besar. Total deformasi yang dihasilkan berkisar 10-40 meter dengan nilai faktor keamanan 0,80~2,34. Oleh karena itu, dari hasil tersebut perlu dipertimbangkan untuk mengkombinasikan kemiringan alur dengan infrastruktur. Kata kunci : faktor keamanan, kemiringan lereng, alur pelayaran, Marine centre, Plaxis

Seismic Facies of Pleistocene–Holocene Channel-fill Deposits in Bawean Island and Adjacent Waters, Southeast Java Sea Ali Albab; Noor Cahyo Dwi Aryanto
BULLETIN OF THE MARINE GEOLOGY Vol 32, No 1 (2017)
Publisher : Marine Geological Institute of Indonesia

The late Pleistocene-Holocene stratigraphic architecture of the Bawean Island and surrounding waters, southeast Java Sea has been analyzed by using sparker seismic profiles. Geological interpretation of these seismic profiles revealed the widespread distribution of paleochannels with different shape and size in the present-day Java Sea. Two channel types can be distinguished based on its morphology: U-shaped channels in the western part and V-shaped channels in the eastern part. The stratigraphic successions were grouped into two major seismic units separated by different seismic boundaries. Characters of marine and fluvial deposits were determined based on seismic boundaries and internal reflectors. Three seismic facies can be identified within late Pleistocene – Holocene incised channel fills associated with SB2. The internal structure of incised-channels consist of chaotic reflector at the bottom, covered by parallel–sub parallel and almost reflection-free indicating the homogenous sediment deposited during the succession.Keywords : Pleistocene-Holocene channel fills, sparker seismic profiles, seismic boundaries, incised–channel, Java Sea. Rekaman seismik sparker digunakan untuk menganalisis endapan stratigrafi berumur Plistosen Akhir–Holosen di Perairan Pulau Bawean dan sekitarnya. Berdasarkan interpretasi geologi dari rekaman seismik tersebut teridentifikasi sebaran alur purba yang berbeda bentuk dan ukuran dengan kondisi Laut Jawa sekarang. Berdasarkan morfologinya, dua tipe alur purba yang terdentifikasi adalah alur purba berbentuk U di bagian barat dan berbentuk V yang terbentuk di bagian timur daerah penelitian. Suksesi stratigrafi kemudian dibedakan menjadi dua grup unit seismik utama yang dibatasi oleh perbedaan batas seismik, yaitu endapan asal darat dan laut yang ditentukan berdasarkan batas sikuen dan reflektor internal. Pada unit Pleistosen–Holosen teridentifikasi tiga tipe fasies seismik yang berkorelasi pada batas sikuen SB2. Struktur internal alur purba yang tertoreh terdiri dari reflektor kaotik yang di bagian bawah, kemudian ditutupi oleh reflektor paralel - sub paralel sampai hampir bebas refleksi yang mengindikasikan terendapkannya sedimen homogen selama suksesi tersebut.Kata kunci : Pengisi alur Plistosen - Holosen, penampang seismik sparker, batas seismik, alur tertoreh, Laut Jawa.

PALYNOLOGY OF TÃ–GI NDRAWA CAVE,COASTAL AREA OF NIAS ISLAND, NORTH SUMATERA A.A Polhaupessy
BULLETIN OF THE MARINE GEOLOGY Vol 24, No 2 (2009)
Publisher : Marine Geological Institute of Indonesia

Environmental study of the TÃ¶gi Ndrawa Cave by means of pollen analysis has been carried out. The interpretation is made based on the occurring pollen types as guide, the resulted pollen spectra, and curves exhibited in the pollen diagram. Combined evidences obtained from the palynological, geological and archaeologi cal studies provide the basis for the interpretation of plant ecology of shore and further the vegetational history of the marine area. In the meantime, plant ecology itself is concerned not only with plant communities but also the interaction among the plants involved, and their environmental factors. Keyword: Environmental, Pollen Analysis, TÃ¶gi Ndrawa Cave Studi lingkungan GuaTÃ¶gi Ndrawa, Pulau Nias, telah dilakukan dengan menggunakan analisis polen. Interpretasi ini berdasarkan hadirnya jenis polen sebagai petunjuk dalam membentuk diagram polen. Hasil studi palinologi, geologi dan arkeologi telah menghasilkan interpretasi dasar mengenai ekologi tumbuhan pantai kemudian sejarah tumbuhan yang pernah tumbuh didaerah laut dangkal. Pada zaman ini, ekologi tumbuhan tidak hanya tergantung komunitas tumbuhan tetapi justru tergantung pada interaksi diantara komunitas tumbuhan dan faktor lingkungannya. Kata Kunci: Lingkungan, Analisis polen, Gua TÃ¶gi Ndrawa

Interpretation of Paleo-Channel Based on Shallow Seismic Reflection Record in Banten Bay, Banten Province Yogi Noviadi
BULLETIN OF THE MARINE GEOLOGY Vol 31, No 1 (2016)
Publisher : Marine Geological Institute of Indonesia

The objective of this study is to find out the pattern of paleo channel which was formed in Banten Bay and its surrounding.Â The aims are to find out the paleo-channel pattern at study area. The study methods are including vessel positioning, and shallow seismic reflection work. Vessel positioning method is to locate the exact position of seismic workÂ Â Â when recording the data from single channel of shallow seismic reflection. Seismic line orientations are determined by regional geological setting of the area. Trend of seismic lines are dominantly north â€“ south. In order to get the seismic data which could give geological setting configuration, seismic lines should be perpendicular to the strikes of the sediments.Based on the calculation of velocity of seismic refraction in sea water 1,500 meters/second, while within sediment 1,600 meters/second, it could be concluded that the paleo chanels were more or less in 32 meters below sea floor depth.This layer was the system that occur during the process of an interglacial on the Sunda Shelf when it was still a part of land that connects the Java, Sumatra and Kalimantan Islands. Paleo-channel deposits are characterized by subparalel - chaotic reflection character with a thickness between 5-35 meters.Keywords: Paleo-channels, seismic records and Banten BayMaksud dari penelitian ini adalah untuk mengetahui pola sungai purba yang terdapat di Teluk Banten dan sekitarnya, yang tujuannya adalah untuk mengetahui pola penyebaran alur sungai purba di daerah penelitian. Metode penelitian terdiri dari penentuan posisi kapal dan penelitianÂ seismik pantul dangkal. Penentuan posisi kapal berguna untuk menemukan posisi yang tepat saat merekam data oleh perlatan seismik saluran tunggal dangkal. Lokasi lintasan seismik disesuaikan dengan kondisi geologi daerah penelitian. Arah lintasan seismik pada umumnya berarah utara â€“ selatan. Untuk mendapatkan data seismik yang bisa memberikan konfigurasi kondisi geologi, lintasan seismik harus tegak lurus terhadap kedudukan lapisan batuan.Berdasarkan cepat rambat gelombang seismik di air laut 1.500 meter/detik, dan sedimen 1.600 meter/ detik, dapat disimpulkan bahwa alur purba kurang lebih berada pada kedalamanÂ 32 meter di bawah dasar laut.Lapisan ini merupakan sistem pengendapan yang terjadi selama proses interglasial di Paparan Sunda yang pada saat itu masihÂ merupakan bagian dari daratan yang menghubungkan P. Jawa, Sumatera dan P. Kalimantan. Endapan alur purbaÂ dicirikan dengan pola refleksi subparalel sampai tidak beraturan dengan ketebalan antara 5-35 meter.Kata kunci: Alur purba, rekaman seismik dan teluk Banten

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

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 108Â°48'30â€ - 109Â°1'30â€ E and 0Â°40'30â€ - 0Â°54'30â€ N and, situated Â± 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 108Â°48'30â€ - 109Â°1'30â€ BT and 0Â°40'30â€ - 0Â°54'30â€ LU dan terletak Â± 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 â€“ 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.

THE GEOCHEMICAL CHARACTERISTIC OF MAJOR ELEMENT OF GRANITOID OF NATUNA, SINGKEP, BANGKA AND SIBOLGA Ediar Usman
BULLETIN OF THE MARINE GEOLOGY Vol 30, No 1 (2015)
Publisher : Marine Geological Institute of Indonesia

A study of geochemical characteristic of major elelemnt of granitoid in Western Indonesia Region was carried out at Natuna, Bangka, Singkep and Sibolga. The SiO2 contents of the granites are 71.16 to 73.02 wt%, 71.77 to 75.56wt% and 71.16 to 73.02wt% at Natuna, Bangka, and Singkep respectively, which are classified as acid magma. While in Sibolga the SiO2 content from 60.27 to 71.44wt%, which is classified as intermediate to acid magma. Based on Harker Diagram, the granites from Natuna, Bangka and Singkep as a co-genetic. In other hand the Sibolga Granite show as a scatter pattern. Granites of Natuna, Bangka and Singkep have the alkaline-total (Na2O + K2O) between 6.03 to 8.51 wt% which are classified as granite and alkali granite regime. K2O content ranges from 3.49 to 5.34 wt% and can be classified as calc-alkaline type. The content of alkaline-total of Sibolga granite between 8.12 to 11.81 wt% and classified as a regime of syenite and granite. The range of K2O is about 5.36 to 6.94wt%, and assumed derived from high-K magma to ultra-potassic types. Granites of Natuna, Bangka and Singkep derived from the plutonic rock types and calc-alkaline magma, while Sibolga granite magma derived from K-high to ultra-potassic as a granite of islands arc. Based on the chemical composition of granite in Western Indonesian Region can be divided into two groups, namely Sibolga granite group is representing the Sumatera Island influenced by tectonic arc system of Sumatera Island. Granites of Bangka and Singkep are representing a granite belt in Western Indonesian Region waters which is influenced by tectonic of back arc.Keywords: magma, geochemical characteristic, major element and Western Indonesian Region Kajian karakteristik geokimia dari unsur utama granitoid di Kawasan Barat Indonesia telah dilakukan di daerah Natuna, Bangka, Singkep dan Sibolga. Kandungan SiO2 granit Natuna antara 71,16 - 73,02%, Bangka antara 71,77 - 75,56%, Singkep antara 72,68 - 76,81% termasuk dalam magma asam. Granit Sibolga memiliki kandungan SiO2 antara 60,27 - 71,44% termasuk dalam magma menengah - asam. Berdasarkan Diagram Harker, granit Natuna, Bangka dan Singkep mempunyai asal kejadian yang sama (ko-genetik), sedangkan granit Sibolga membentuk pola pencar. Granit Natuna, Bangka dan Singkep mengandung total alkalin (K2O+Na2O) antara 6,03 - 8,51% termasuk dalam jenis rejim granit dan alkali granit. Berdasarkan kandungan K2O antara 3,49 - 5,34 %berat, bersifat kalk-alkali. Granit Sibolga mengandung total alkali antara 8,12 - 11,81% termasuk dalam rejim syenit dan granit, dan berdasarkan kandungan K2O antara 5,36 - 6,94% berasal dari jenis magma K-tinggi sampai ultra-potassik. Granit Natuna, Bangka dan Singkep berasal dari jenis batuan beku dalam dan magma kalk-alkalin yang berhubungan dengan penunjaman, sedangkan granit Sibolga berasal dari jenis magma K-tinggi - ultra-potassik sebagai granit busur kepulauan. Berdasarkan komposisi unsur kimia utama, granit di Kawasan Barat Indonesia dapat dibagi dalam dua, yaitu granit Sibolga yang mewakili P. Sumatera, dipengaruhi oleh sistem tektonik busur P. Sumatera. Granit Bangka dan Singkep dapat mewakili suatu jalur granit di perairan Kawasan Barat Indonesia yang dipengaruhi oleh tektonik busur belakang. Kata kunci: jenis magma, karakteristik geokimia, unsur utama, dan Kawasan Barat Indonesia

MAGNETIC ANOMALY PATTERNS USING TREND SURFACE ANALYSIS APPLICATION (TSA) ON MARINE GEOLOGY MAPPING IN THE BALIKPAPAN WATERS Delyuzar Ilahude
BULLETIN OF THE MARINE GEOLOGY Vol 27, No 1 (2012)
Publisher : Marine Geological Institute of Indonesia

The application of Trend Surface Analysis (TSA) method an geological and geophysical research in map sheets 1813-1814, Balikpapan Waters and its surrounding, shows the significant value of residual anomaly. The magnetic disseverance of regional and total anomaly value obtained the negative anomaly between -50 nT and -350 nT and positive anomaly between +50 nT and +400 nT. The contour of total and regional anomaly shows the magnetic properties of rocks which characterizes the geological arrangements of the research areas. Residual anomaly yielded from the 2nd order value of regional anomaly might be correlated with the formation of basin structures in the central and northern parts of research area, which is interpreted as a part of Kutai Basin. Keywords : TSA method, magnetic anomaly, geology and geophisics, Balikpapan Waters. Penerapan metode TSA dalam penelitian geologi dan geofisika di Lembar Peta 1813-1814, Perairan Balikpapan dan sekitarnya menunjukkan nilai anomali sisa yang cukup signifikan. Hasil pemisahan nilai anomali magnet regional dan anomaly total diperoleh nilai anomali yaitu antara -50 nT dan â€“350 nT dan anomali positif antara +50 nT dan +400 nT. Kontur anomali total dan anomali regional memperlihatkan sifat kemagnitan batuan yang mencirikan tatanan geologi daerah penelitian. Anomali sisa dihasilkan dari nilai anomali regional orde ke 2, kemungkinan berkaitan dengan pembentukan struktur cekungan di bagian tengah dan utara daerah penelitian yang ditafsirkan sebagai bagian dari Cekungan Kutai. Kata kunci : metode TSA, anomali magnet, geologi dan geofisika, Perairan Balikpapan.

THE CORRELATION BETWEEN BENTHIC FORAMINIFERA AND SEDIMENT TYPES OF SOUTH MAKASSAR STRAIT Sheilla Zallesa; Kresna Tri Dewi; Noor C.D. Aryanto
BULLETIN OF THE MARINE GEOLOGY Vol 29, No 2 (2014)
Publisher : Marine Geological Institute of Indonesia

South Makassar Strait is located between Kalimantan and Sulawesi Islands that is an important oceanographic pathway connecting between the Pacific and Indian oceans. This area is a part of sedimentary basin that has specific seabed morphology and sediment characteristics, including foraminifera as a component of sediments. The purpose of this study is to determine community structure of benthic foraminifera related to sediment characteristics. This study used 20 top core sediment samples from water depth between 200 and 1500 m. There are identified 38 species of benthic foraminifera and some of them are characterized the study area: Anomalinoides colligerus, Lenticulina suborbicularis, Planulina wuellerstorfi, , and Pseudonodosaria discrete. The diversity index is categorized as moderate values (1.0=H'= 3) and the average of evenness values is about 0.79. The dominance values are less than 0.5 indicate that there is no dominant species in the study area. In relation to sediment characteristics, it shows that the high abundance of benthic foraminifera occurs in sediment type of silty sand and sandy silt. Moderate abundance appears in sand following by low abundance in silt and sandy silt sediment types. Keywords: benthic foraminifera, community structure, sediment types and Makassar Strait Makassar bagian selatan terletak diantara Pulau Kalimantan dan Sulawesi yang merupakan jalur oseanografik yang penting menghubungkan Samudera Pasifik dan. Wilayah ini merupakan bagian dari cekungan sedimen yang mempunyai morfologi dasar laut dan karakteristik sedimen tertentu termasuk foraminifera sebagai komponen sedimen. Tujuan dari penelitian ini adalah untuk mengetahui struktur komunitas foraminifera bentik dalam kaitannya dengan tipe sedimen dasar laut. Penelitian ini menggunakan 20 sampel sedimen bagian atas dari pemercontoh inti pada kedalaman antara 200 dan 1500 m. Ada 38 spesies foraminifera bentik dan beberapa diantaranya mencirikan daerah penelitian: Anomalinoides colligerus, Lenticulina suborbicularis, Planulina wuellerstorfi, dan Pseudonodosaria discrete. Indeks keanekaragaman termasuk dalam kategori sedang (1,0=Hâ€™=3) dan nilai rata-rata keseragaman sekitar 0,79. Nilai dominasi lebih kecil dari 0,5 itu menandakan tidak ada spesies yang dominan pada lokasi penelitian. Terkait dengan karakteristik sedimen menunjukkan bahwa kelimpahan foraminifera bentik tinggi terdapat pada jenis sedimen pasir lanauan dan lanau pasiran. Kelimpahan sedang ditemukan pada jenis sedimen pasir diikuti kelimpahan rendah yang dijumpai pada sedimen lanau dan lanau pasiran. Kata kunci: foraminifera bentik, struktur komunitas, jenis sedimen, Selat Makassar.

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