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The Mechanism of Sediment Depositional Environment of Core Drilling of Gilimanuk Coast, Bali and Ketapang, East Java, Based on Sediment Textures
Get PDFThe analysis result of grains frequency curve and relation between grains size to cumulative have shown medium grains at Gilimanuk (Core drilling-1) and coarse grains at Ketapang (Core drilling-2). In general both of them are showed by pattern uniformity, which is represented by the similar of curve pattern. On the grain size of -2 phi as medium gravel with percentage between 6.47 to 35.88%, while core drilling -2 on the size of -2 phi between 6.86 to 61.11%.The average grains size of core drilling -1 are gravel about 21.3%, sand 60.2%, silt 5% and clay about 0.4% while core drilling-2 are characterized by 44.3%, sand 26.8%, silt 24.6% and clay about 0.6%. These result shows that at location of Core drilling -1 is dominated by sand where as at location of Core drilling -2 is dominated by gravel. These situation can be interpreted that the sediment at core drilling -2 location have influenced by strong marine current which can transport the large amount of gravel size compare to the location of Core drilling-1 which is dominated by sand. Based on the relation shape of grains size curve versus cumulative frequency shows that the sediment of Core drilling-1is interpreted as a beach sand deposits and only one sample which shows as a river sand deposits which was found at depth 0 – 3 m depth. In general, the sample of Core drilling –2 shows that the pattern of sediment tend as a beach sand deposits and only one sample which shows the combination between coastal deposits and river deposits ( 4 – 5 m depth). From this sample, the coarse to fine grains is deposited by coastal media and fine grains material (about 10%) is deposited by river media. The sample of river deposits is found as lamination because the only one which is created from combination between coastal and river depos its from all sample of core drilling-2.Keywords: core drilling, grain sediments, media transport, environmental deposition Hasil analisis menggunakan kurva frekuensi butiran serta hubungan antara besar butir terhadap kumulatif menunjukkan dominasi ukuran butiran sedang di daerah Gilimanuk (Bor-1) dan kasar di daerah Ketapang (Bor-2). Pada kedua daerah tersebut, secara umum memperlihatkan pola keseragaman, yang ditunjukkan oleh pola kurva yang sama. Pada ukuran butir -2 phi (kerikil sedang) pada Bor-1 berjumlah antara 6,47 – 35,88%, sedangkan pada Bor-2 pada ukuran -2 phi berjumlah antara 6,86 – 61,11%.Kandungan rata-rata butiran pada Bor-1 adalah: kerikil 21,3%, pasir 60,2%, lanau 5% dan lempung 0,4%, sedangkan Bor-2 adalah: kerikil 44,3%, pasir 26,8%, lanau 24,6% dan lempung 0,6%. Hasil ini menunjukkan bahwa pada Bor-1 didominasi oleh pasir dan pada Bor-2 didominasi oleh kerikil. Hasil ini dapat memberi gambaran bahwa pada Bor-2 berarus lebih kuat karena mampu menstranspor butiran kerikil dalam jumlah yang lebih besar dibandingkan dengan Bor-1 yang didominasi oleh pasir. Berdasarkan beberapa kurva hubungan antara besar butir vs frekuensi komulatif pada Bor-1 menunjukkan endapan pantai (beach sand), hanya satu contoh menunjukkan endapan sungai (river sand), yaitu contoh B1 (0 – 3m). Pada Bor-2, secara umum menunjukkan pola yang lebih mendekati endapan pantai (beach sand), hanya satu contoh menunjukkan kombinasi endapan pantai dan endapan sungai (river sand), yaitu contoh B2 (4 – 5 m). Pada contoh ini, butiran berukuran kasar sampai halus diendapkan oleh media pantai dan ukuran halus dengan persentase sekitar 10% merupakan endapan sungai. Contoh endapan sungai adalah pada B2 (4 – 5 m) ini merupakan endapan sisipan karena satu-satu terbentuk dari kombinasi pantai dan sungai dari seluruh contoh pada Bor-2.Kata kunci: pemboran inti, butiran sedimen, media transport, lingkungan pengendapa
RESPON MIKROFAUNA (OSTRACODA) TERHADAP KONDISI LINGKUNGAN SEKITAR PULAU BANGKA, SULAWESI UTARA
Get PDFOstracoda merupakan kelompok mikro-organisme yang dapat terawetkan dalam sedimen dasar laut, termasuk dasar perairan sekitar Pulau Bangka, Sulawesi Utara. Pulau ini terkenal akan keindahan alam bawah laut dan penambangan bijih besi di kawasan pesisir. Perubahan lingkungan di pesisir tersebut secara tidak langsung berpengaruh terhadap kondisi dasar perairan laut sebagai habitat biota. Tujuan dari penelitian ini adalah untuk mengetahui respon ostracoda terhadap perubahan lingkungan perairan tersebut. Studi ini menggunakan 10 sampel sedimen dasar laut hasil cucian dilanjutkan dengan analisa mikropaleontologi (tahap penjentikan, identifikasi spesies, penghitungan spesimen dari setiap spesies, pengolahan data, dokumentasi spesimen) dan analisa sedimentologi (SEM-EDX). Keterdapatan Bairdopillata, Neonesidea, Paranesidea dan Quadracythere (BL16-010) yang hidup berasosiasi dengan kondisi terumbu karang mencerminkan suatu perairan dalam kondisi cukup bagus. Di titik lokasi lain (BL16-015 dan BL16-030) ditemukan mikrofauna dengan cangkang abnormal (rusak, kehitaman) yang mengandung C (59-86%), Al2O3(2%), SiO2 (1-7%), dan MnO (2%). Dijumpainya cangkang abnormal merupakan salah satu respon mikrofauna terhadap perubahan lingkungan di daerah penelitian.Kata Kunci: ostracoda, cangkang abnormal, SEM-EDX, Pulau Bangka, Sulawesi Utara Ostracoda is a group of micro-organism that could be preserved in marine sediments, including on the seafloor of Bangka Island, North Sulawesi. This island is famous as beautiful underwater place and iron mining in the coastal area. The environmental changes in the coastal area indirectly influence the seafloor condition as biotic habitats. The purpose of this study is to know the response of ostracoda to this coastal environmental change. This study used ten washed residue of surface sediment samples followed by micropaleontological analysis (picking, identification of species, specimen calculation every species, data processing, specimen documentation), and sedimentological analysis (SEM-EDX). The occurrences of Bairdopillata, Neonesidea, Paranesidea dan Quadracythere (BL16-010) that associated with coral reef communities reflect a good marine condition. In another sampling location (BL16-015 and BL16-030), it is found abnormal microfaunas (broken, blackish) that composed of C (59-86%), Al2O3 (2%), SiO2 (1-7%), and MnO (2%). The finding of these abnormal shells is one of the microfaunal response to environmental changes in the study area. Keywords : ostracoda, abnormal shell, SEM-EDX,Bangka Island, North Sulawes
The Study of Seafloor Tin Placer Resources of Quaternary Sediment at Toboali Waters, South Bangka
Get PDFBangka Island has primary and secondary tin deposit. However, along the history of tin mining has been done the primary tin deposit domination is less than secondary tin deposit. Secondary tin deposit is formed from Granitic S-type source rock weathering and then transported by gravity. After that, Cassiterite mineral (SnO2) accumulates and forms a placer deposit in the study area. The thickness of sediment cover at Toboali Waters is quite diverse, with a range between 5-20 milliseconds, by knowing the quarter sediment thickness using seismic data interpretation results, is expected to give an idea about tin placer deposit potential in Toboali waters. Based on the Isochron map shows patterns of quaternary sediment thickening to the southwest, south and southeast of Bangka Island.Keywords: Quaternary sediment, placer deposit, isochron map, Toboali WatersPulau Bangka memiliki endapan timah primer dan endapan timah sekunder. Namun, sepanjang sejarah penambangan timah yang telah dilakukan endapan timah primer tidak mendominasi jika dibandingkan dengan endapan timah sekunder. Pembentukan endapan timah sekunder berawal dari pelapukan batuan Granit tipe-S yang kemudian mengalami transportasi akibat adanya gravitasi. Setelah itu, mineral kasiterit (SnO2) terakumulasi dan membentuk endapan plaser di daerah penelitian. Ketebalan sedimen penutup di Perairan Toboali berkisar antara 5-20 milidetik, dengan mengetahui ketebalan sedimen kuarter berdasarkan interpretasi data hasil rekaman seismik diharapkan dapat memberikan gambaran tentang potensi endapan timah placer di Perairan Toboali. Berdasarkan atas peta isokron, memperlihatkan bahwa pola penebalan sedimen kuater ke arah baratdaya, selatan dan tenggara Pulau Bangka.Kata kunci : Sedimen kuarter, endapan placer, peta isokron, Perairan Toboal
Temporal and Spatial Distribution of Heavy Metal in Sediment of Urban Coastal Waters: A Case Study in Jakarta Bay, Indonesia
Get PDFHeavy metals, hazardous chemical substances, increase in marine environment due to anthropogenic discharges. However, due to the hydrodynamic of the marine system these metals could vary both temporal and spatial distribution of metals in Jakarta Bay. This study was to reveal the temporal and spatial distribution of metals in sediment over the bay and to assess the environmental condition. Sediment samples were collected in11 stations of March (transitional season) and June(dry season)2013. The result showed that the concentration of heavy metals varied spatially, in which elevated concentration occurred adjacent terrestrial indicating the enrichment of metal-anthropogenic source, but insignificant temporarily.Keywords: heavy metals, spatial distribution, temporal distribution, anthropogenic activities, Jakarta Bay. Logam berat merupakan bahan berbahaya yang tersebar di lingkungan laut karena pengaruh aktifitas antropogenik. Akan tetapi, logam berat ini dapat terdistribusi secara temporal ataupun spasial di Teluk Jakarta akibat sistem hidrodinamika laut. Tujuan dari penelitian ini adalah untuk mengetahui distribusi spasial dan temporal logam berat dalam sedimen dan untuk menilai kondisi lingkungan teluk. Sedimen diambil dari 11 stasiun pada bulan Maret (musim transisi) dan Juni (musim kering) tahun 2013. Hasil penelitian menunjukkan bahwa distribusi spasial logam berat bervariasi, dimana konsentrasinya meningkat di lokasi dekat daratan yang mengindikasikan tingginya sumber logam-antropogenik namun secara temporal tidak signifikan.Kata kunci: logam berat, distribusi spasial, distribusi temporal, kegiatan antropogenik, Teluk Jakarta
KARAKTERISTIK MORFOLOGI DASAR LAUT DAN HUBUNGANNYA DENGAN KECEPATAN ARUS LAUT DI SELAT LAMPA, NATUNA, KEPULAUAN RIAU
Get PDFKondisi morfologi dasar laut dari suatu perairan khususnya di selat dapat mempengaruhi kecepatan arus laut. Indonesia sebagai negara kepulauan memiliki banyak pulau dan selat. Bertambahnya kecepatan arus laut dapat dimanfaatkan sebagai salah satu sumber energi yang ramah lingkungan. Selat Lampa yang berada di Pulau Natuna merupakan salah satu wilayah dari pulau-pulau kecil di Provinsi Kepulauan Riau yang masih mengalami krisis energi listrik. Hasil pengukuran kedalaman laut di lokasi penelitian secara keseluruhan berkisar antara 0 meter dan 59,59 meter. Dari hasil penelitian diketahui bentuk morfologi bawah laut pada lokasi ini pada umumnya relatif landai dengan kemiringan sekitar 5o– 10o. Namun pada bagian selat antara Pulau Setanau dan Pulau Setahi memiliki morfologi yang agak curam yang ditunjukkan oleh kontur yang lebih rapat dengan kedalaman berkisar 5 meter sampai dengan 30 meter. Hasil pengukuran dan pemodelan kecepatan arus laut menunjukkan bahwa pada lokasi selat antara Pulau Setanau dan Pulau Setahi memiliki kecepatan arus laut berkisar antara 0,3 meter/detik sampai dengan 1,28 meter/detik. Sehingga lokasi ini sesuai untuk penempatan turbin pembangkit listrik tenaga arus laut.Kata Kunci : Morfologi dasar laut, Kecepatan arus laut, Energi arus laut, Pulau-pulau kecil terluar, Selat Lampa, Pulau Natuna, Kepulauan Riau, Potensi energi listrik tenaga arus lautThe morphology condition of the seabed, especially in the strait, can affect the velocity of ocean currents in these waters. Indonesia as an archipelagic country has many islands and straits. Increasing the speed of ocean currents will be very potential to be utilized as one source of alternative energy that is environmentally friendly. Lampa Strait located on the island of Natuna is one of the small islands in Riau Islands Province which is still experiencing energy crisis. This location was chosen as the location of research for the potential energy of Tidal current. The results of sea depth measurements at the study sites overall ranged between 0 meters and 59.59 meters. From the results of the research is known the underwater morphology at this location is generally relatively sloping with a slope of about 5o to 10o But in the strait between the island of Setanau and Setahi Island has a rather steep morphology shown by a more dense contour with a depth ranging from 5 meters to with 30 meters. The result of ocean current measurement and modeling shows that at the location of the strait between Setanau Island and Setahi Island has a stronger ocean current speed ranging from 0,3 meters / second to 1,28 meters / second. So this location is suitable for the placement of turbines of Tidal current power plants.Keywords : Sub Bottom Profile, Ocean Current speed, Tidal Current Energy, Small outer islands, Lampa Strait, Natuna Island ,Riau Island, potential energy of Tidal current
PROSES SEDIMENTASI CEKUNGAN BONE BERDASARKAN PENAFSIRAN SEISMIK REFLEKSI DI PERAIRAN TELUK BONE SULAWESI SELATAN
Get PDFSecara geologi, Cekungan Bone terletak diantara Lengan Sulawesi Selatan dan Lengan Sulawesi Tenggara. Cekungan Bone terbentuk pada Paleogen-Neogen dan telah mengalami beberapa kali proses tektonik serta aktivitas magmatik. Morfologi Cekungan Bone dikontrol oleh beberapa sistem sesar yaitu sesar Walanae, Palukoro dan lainnya. Sesar-sesar ini selama Plio-Pleistosen hingga Kuarter mempengaruhi proses sedimentasi pada cekungan ini. Pada tahap awal, cekungan Bone terbentuk akibat dari proses subduksi lalu berkembang menjadi cekungan intermontane. Didalam Cekungan Bone tersebut terdapat beberapa sekuen yang ditafsirkan dari penampang seismik pantul, dimulai dari Kala Paleosen sampai Oligosen Awal diendapkan sekuen A. Sekuen A ditutupi Sekuen B secara tidak selaras pada Kala Oligosen Awal sampai Oligosen Akhir. Di atas sekuen B ini diendapkan Sekuen C secara tidak selaras yang mulai terbentuk pada umur Oligosen Akhir hingga Miosen Awal. Sekuen berikutnya diendapkan Sekuen D yang terbentuk pada saat Miosen Awal hingga Miosen Akhir dan ditutupi Sekuen E pada lingkungan laut dangkal hingga darat. Endapan yang paling atas adalah sekuen F yang berumur Kuarter dan sebagai sedimen pengisi lembah-lembah yang dipengaruhi oleh adanya sesar Walanae yang teraktifkan kembali. Kata Kunci : cekungan Intermontane, sesar Walanae yang teraktifkan kembali, cekungan Bone Geologically, the Bone Basin is situated in between south Sulawesi Arm and southeast Sulawesi Arm. The Basin was formed on the Paleogene-Neogene time and has repeatedly processed in terms of tectonics and magmatic activities. The morphology of Bone Basin was formed by some faults system, there are Walanae Fault, Palukoro Fault and others. These faults during Plio-Pleistocene up to Quaternary times were affected their sediment of the basin. In the beginning, the Bone Basin was formed by subduction and then developed become intramontane basin. In The Bone basin there are some sequences that are interpreted from seismic reflection, started from Palaeocene to Early Oligocene was marked by A sequence. Then, it was overlied unconformity by B sequence of Early Oligocene to Late Oligocene. On the top of B sequence was deposited unconformitily by C sequence which was formed from late Oligocene to Early Miocene. Furthermore, D sequence was deposited during Early Miocene to Late Miocene and covered by E sequence of shallow marine to terrestrial environments. The youngest is F sequence which formed in the Quaternary age and as a channel filed sediment was influenced by reactivated of Walanae Fault.Keywords : Intramontane basin, reactivated of Walanae Fault, Bone Basi
Calcareous Nannoplankton (marine algae) Analysis in Subsurface Sediments of Andaman Sea
Get PDFAndaman Sea in the Indo-Pacific Warm Pool (IPWP) is influenced by Indo-Australia monsoon winds. Marine sediment cores in this area, BS36 (06°55’50.8”N; 96°07’28.51”E; ; Water depth 1147.1 meters) were acquired by Geomarin III research vessel andanalysed its morphology for nannoplankton occurences. Results from qualitative identification on marine sediment core in Andaman Sea obtained 11 genus of nannoplankton marine algae in this area. Dominated genus discovered in this site is Gephyrocapsa, Emiliania, and Helicosphaera. Although this research is qualitative and preliminary study phase; however, this reference of modern nannoplankton taxonomy and features using Scanning Electron Microscope (SEM) would enhance marine algae biodiversity along Andaman Sea of Indonesian watersKeywords: Nannoplankton, morphology, sediment core, taxonomy, Andaman Sea Kawasan Laut Andaman terletak di wilayah kolam panas Indo-Pasifik sangat dipengaruhi oleh angin musim Indo-Australia. Conto inti sedimen laut di wilayah BS 36 (06°55’50.8” Utara; 96°7’28.51” Timur; kedalaman laut 1147,1 meter) diambil menggunakan wahana kapal riset Geomarin III dan dianalisis morfologi nanoplankton yang ditemukan di wilayah ini. Hasil dari pemerian kualitatif dari conto sedimen inti di Laut Andaman menghasilkan 11 genus nanoplankton sebagai alga laut yang dapat ditemukan pada lokasi ini. Genus yang sangat menonjol di satu lokasi titik pengambilan conto sedimen inti yaitu Gephyrocapsa, Emiliania, dan Helicosphaera. Meskipun kajian ini masih bersifat kualitatif dan tahap studi awal; namun acuan tentang taksonomi nanoplankton modern dan kenampakan dari Scanning Electron Microscope (SEM) akan memperkaya biodivesitas alga laut di sepanjang Laut Andaman dari perairan Indonesia.Kata Kunci: Nanoplankton, morfologi, conto sedimen inti, taxonomi, Laut Andama
The Content of Placer Heavy Mineral and Characteristics of REE at Toboali Coast and Its Surrounding Area, Bangka Belitung Province
Get PDFBangka Island and surrounding areas (including coast and seabed sediments) is known as main tin producer (cassiterite) in the world as these part of the Southeast Asia Granitic belt, but in fact, other than as a producer of tin, Bangka Belitung is also as heavy mineral placer (as accessories mineral) and REE potential producer which one based on the geological conditions.The potential of accessories minerals on sediment coast, other than cassiterite that occurs around Betumpak Cape, i.e: magnetite (7.86 %), ilmenite (4.9%), zircon (2.51%) and apatite (1.07%) respectively with content. While the content of monazite by using a hand drill has the potential content of up to 67.8 g/m3, while the content of monazite hypothetical resources off the coast of Bangka approximately 471,087,689 m3. As for the content of monazite hypothetical resources off the coast of South Bangka are approximately 23,995,820 m3.At Toboali coast, South Bangka the presence of REE in sediments are above the Earth's crust generally. They’re concentrations, such as La (5.07 to 199 ppm), Ce (106-394 ppm), Pr (5.11-59.7 ppm), Nd (16.5-201 ppm), Sm (9.97-52.3 ppm), Eu (0.18-1.55 ppm), Gd (9.11-39.3 ppm), Tb (1.35-8.14 ppm), Dy (9.01-56.3 ppm), Ho (1.89-12.3 ppm), Er (5.19-33.9 ppm), Tm (0.77-5.62 ppm), Yb (3.3-37.5 ppm) and Lu (0.71-5.41 ppm). LREE (La-Eu) highest content is generally found in the location of the tailings sludge (TBL-13C), not so in HREE (Gd-Lu), the highest content is widely available on the sandy beach sediments (TBL-13B). Tectonic environment of Toboali granitoid rocks by plotting a spider diagram refers to the chondrite normalization is continental magmatic arc.Keywords: Placer heavy mineral, REE, Granitic Belt, Bangka Belitung Province. Pulau Bangka dan daerah sekitarnya (termasuk di pantai dan sedimen dasarlaut) telah lama dikenal sebagai penghasil timah (kasiterit) utama di dunia sebagai dari bagian Jalur Granit AsiaTenggara, selainmineral berat sebagai pembawa unsur tanah jarang (UTJ) sangat dimungkinkan mengingat kondisi geologinya.Potensi mineral ikutan di sedimen pantai selain kasiterit, seperti di pantai Muntok antara lain, seperti magnetit (7,86%), ilmenit (4,9%), zirkon (1,32%) dan apatit (1,07%). Adapun kandungan monasit berdasarkan hasil pemboran tangan memperlihatkan kandungan hingga 67,8 g/m3 dengan kandungan potensi sumber daya di seluruh Pantai Bangka sekitar 471.087.689 m3 dengan potensi sumberdaya hipotetik di Pantai Bangka Selatan mendekati 23.995.820 m3. Di Pantai Toboali, Bangka Selatan kehadiran Unsur Tanah Jarang (UTJ) dalam sedimen, umumnya di atas konsentrasi kerak bumi. Kandungan unsur tanah jarang tersebut, seperti La (5,07 - 199 ppm), Ce (106-394 ppm), Pr (5,11-59.7 ppm), Nd (16,5-201 ppm), Sm (9,97-52,3 ppm), Eu (0,18-1,55 ppm), Gd (9,11-39,3ppm), Tb (1,35-8,14 ppm), Dy (9,01-56,3 ppm), Ho (1,89-12,3 ppm), Er (5,19-33,9 ppm), Tm (0,77-5,62 ppm), Yb (3,3-37,5 ppm) dan Lu (0,71-5,41 ppm). Kandungan tertinggi unsur tanah jarang ringan (UTJ-R) seperti La hingga Eu umumnya dijumpai pada lokasi tailing (TBL-13C) berbeda halnya dengan unsur tanah jarang berat (UTJ-B), kandungan tertingginya dijumpai pada sedimen pantai pasiran (TBL-13B). Berdasarkan hasil perajahan pada diagram laba-labanya, memperlihatkan bahwa lingkungan tektonik granit Toboali merupakan busur benua magmatik. Kata kunci: Mineral berat letakan, Unsur Tanah Jarang (UTJ), Jalur Granit, Provinsi Bangka Belitun
KETERDAPATAN MINERAL LEMPUNG SMEKTIT YANG MEMPUNYAI SIFAT PLASTISITAS TINGGI DI PERAIRAN CIREBON, JAWA BARAT
Get PDFSalah satu masalah dalam pembangunan infrastruktur di atas tanah lempung adalah sifatnya yang mengembang (swelling). Tujuan penelitian adalah untuk mengetahui sifat fisik dan keteknikan tanah lempung di perairan Cirebon. Metode penelitian meliputi pemboran, besar butir, analisis mineral dan uji Atterberg. Hasil analisis ukuran butir dari contoh tanah tidak terganggu didominasi oleh lempung, sedangkan mineral lempungnya menunjukkan jenis smektit yang lebih banyak dari pada kaolinit. Kaolinit dan montmorilonit mempunyai kadar air yang tinggi. Nilai plastisitasnya tinggi sampai sangat tinggi dengan nilai aktifitas di atas 0,5. Berdasarkan hasil uji Atterberg plastisitas Index lempung dengan nilai >17 dapat dikategorikan bersifat plastisitas tinggi dan kompak (High Plasticity and cohesive). Kata kunci : Mineral smektit, plastisitas tinggi, uji Atterberg, analisis mineral lempung, perairan Cirebon.One of the problems in the construction of infrastructure on top of clay is that it is expanding (swelling). The research objective was to determine the physical and engineering properties of clay in the waters of Cirebon. Methods of research include drilling, grain size analyses, mineral analysis and Atterberg test. The results of the analysis of the grain size of the sample undisturbed soil dominated by clay which are indicated and dominated by smectite rather than kaolinite. Kaolinite and monmorilonite are high in water content. The plasticity value is high to very high with activity value above 0.5. Based on the results of Atterberg test, clay plasticity index with values >17 can be considered to be of high plasticity and compact (High Plasticity and cohesive).Keywords: smectite minerals, high plasticity, Atterberg test, clay minerals analysis, Cirebon waters