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Keberadaan sebaran sedimn pasir dasar laut berdasarkqn data seismik Di Daerah Pulau Rupat, Kabupaten Bengkalis, Kepulauan Riau
No full textPenelitian keberadaan sebaran sedimen pasir laut dilakukan di daerah Perairan timur Pulau Rupat, Kabupaten Bengkalis, Kepulauan Riau. Tujuan dari penelitian ini adalah untuk mengetahui keberadaan pasir laut dengan mempertimbangkan karakter, volume dan kandungan pasir silika pada endapan dasar laut berdasarkan pola seismik refleksi. Metode penelitian yang digunakan adalah seismik pantul dangkal saluran tunggal (single channel) dengan menggunakan sumber gelombang suara Boomer, dengan energi sebesar 600 Joule. Berdasarkan pola reflektornya unit fasies seismik dibagi menjadi 3 unit yaitu: unit 1, unit 2 dan unit 3. Unit 1 diduga merupakan sedimen paling muda (sedimen resen) dengan fraksi pasir hingga fraksi halus (lumpur) dan bersifat relatif melampar karena tingkat sedimentasinya yang relatif seragam. Ketebalan unit 1 ini secara umum memperlihatkan ketebalan antara 0-48 meter dengan dominasi ketebalan berkisar 30–36 meter dan menunjukkan adanya perubahan ketebalan yang signifikan pada beberapa lokasi. Unit 2 merupakan unit yang diendapkan di bawah unit 1 dengan pola reflektor yang memperlihatkan subparalel- chaotic dan sebagian menunjukkan fitur acoustic blank, dominan kontinyuitas reflektornya sedang- rendah. Tetapi, pada sebagian tempat yang ditemukan fitur acoustic blank terjadi diskontinyuiti. Amplitudo reflektor pada unit ini bersifat sedang-rendah. Pola ketebalan sedimen unit 2 secara umum memperlihatkan ketebalan antara 2–58 meter dengan dominasi ketebalan berkisar 28–32 meter
VARIABILITY OF SEA SURFACE TEMPERATURE AND SALINITY IN MAKASSAR STRAIT DURING THE LAST GLACIAL MAXIMUM
Full text linkIndonesian Throughflow (ITF), which is part of the global thermohaline circulation, is known to play an important role in the heat exchange between the Pacific and Indian Oceans. The flow of the ITF is highly complex, it depends on temperature and salinity. This study presents a proxy study from 25,000–18,000 years ago from two sites that are connected by the Indonesian Throughflow in the Makassar Strait. Oceanographic characteristics, including Sea Surface Temperature (SST) and Sea Surface Salinity (SSS) were reconstructed and analyzed during the Last Glacial Maximum (LGM) period. A 295 cm marine sediment core coded SO217-18522 (1°24.106'N; 119°04.781'E, water depth 978 m) and SO217-18519 (0°34.329'N; 118°06.859'E, water depth 1658 m) from the SONNE 217 research cruise in 2011 was used as research material. Oxygen isotope analysis, planktonic foraminiferal Mg/Ca geochemistry, and radiocarbon dating were used in this study. The SST reconstruction shows that the temperature during the LGM reach the minimum during ~20 ka BP and the SST value was significantly lower by ~2–3 °C compared to the Late Holocene value. The SST also shows significant cooler in marine sediment SO2017-8519 located in the southern site compared to the northern site. Salinity reconstructions during the LGM shows that SSS value was 0.82–1.13 psu higher than in the Holocene. The south–north gradients of SST and SSS in the Makassar Strait were larger over the 23.2–24.2 ka BP (SST gradient by 0.5–1 °C and SSS gradien by 1–1.7 psu) compared to the Late Holocene. The increase in SST and SSS gradients during the ~20 ka BP likely indicates a weakened intensity of the surface ITF relative to conditions during the Late Holocene
SEASONAL AND INTRA-SEASONAL VARIABILITY OF OCEAN THERMAL POTENTIAL ENERGY IN THE INDONESIAN EXCLUSIVE ECONOMIC ZONE
Full text linkOcean thermal energy is a promising marine renewable energy resource that can be developed as a clean energy alternative for Indonesia, which is in the equatorial or tropical region. This study assesses the potential of ocean thermal energy as a renewable energy source in the Indonesian Exclusive Economic Zone (EEZ) by estimating the monthly, seasonal, and intra-seasonal variability of ocean thermal energy conversion (OTEC) resources. The Indonesian EEZ spans from 6°N to 11°S and 95°E to 139°E, covering an area of 3,495,698.72 km². Using temperature data from simulations of the Hybrid Coordinate Ocean Model (HYCOM), the study evaluates the potential of OTEC resources over a 50-year period (from January 1964 to December 2013) with a spatial resolution of 0.125°. Estimation of OTEC potential power resources was based on temperature differences at depths of 20 m and 1000 m, following the hybrid cycle working principle.The results of the estimations indicate that the area has a monthly average potential power of 289.73 GW. The estimation also reveals seasonal and intra-seasonal variability in this potential energy, with fluctuations ranging from 280.09 GW in August to 295.65 GW in December, influenced by phenomena such as ENSO (El Niño Southern Oscillation) and IOD (Indian Ocean Dipole). In the Indonesian EEZ, the average potential thermal power decreases to 288.23 GW during an El Niño event and increases to 291.72 GW during a La Niña event. The IOD phenomenon has a similar effect, with potential decreasing to 281.82 GW during a positive IOD event and rising to 292.64 GW during a negative IOD event
PENGUKURAN KESEHATAN DAN LUASAN MANGROVE DI KECAMATAN MUARAGEMBONG: PENDEKATAN ANALISIS KERAPATAN TAJUK
Full text linkKecamatan Muaragembong sebagai muara dari Sungai Citarum, mengalami dinamika ekosistem yang signifikan akibat peningkatan intensitas abrasi dan sedimentasi di area pesisir yang berpotensi mempengaruhi kondisi ekosistem sekitarnya, khususnya ekosistem mangrove. Penelitian ini bertujuan untuk mengevaluasi dan memperkirakan tingkat kesehatan, kerusakan, dan luas total ekosistem mangrove di Kecamatan Muaragembong melalui analisis kerapatan tajuk. Data kerapatan tajuk dikumpulkan di lapangan menggunakan metode purposive stratified sampling dengan pendekatan fotografi hemisferik. Hasil klasifikasi menunjukkan luas total mangrove yang berhasil dipetakan seluas 1.073,65 ha, dengan koefisien Kappa sebesar 0,87, menandakan tingkat akurasi yang sangat baik. Evaluasi kesehatan komunitas mangrove mengungkapkan, bahwa 49,66% dari area mangrove berada dalam kondisi baik, 19,80% dalam kondisi normal, dan 30,54% dalam kondisi buruk. Data kerapatan tajuk menunjukkan hubungan sedang dengan koefisien determinasi sebesar 0,4219 (42,19%), yang dipengaruhi oleh faktor eksternal dan resolusi spasial citra yang digunakan
ENVIRONMENTAL CHANGES DURING THE LATE MIOCENE TO PLEISTOCENE USING SMALL FORAMINIFERA AND PALYNOMORPHS IN THE KUTAI BASIN, EAST KALIMANTAN
Full text linkThe Kutai Basin is one of the large basins in East Kalimantan which was formed during the Tertiary Period. The sedimentation process in this basin is strongly influenced by sea level changes. This study conducts quantitative analysis using the abundance of small foraminifera and palynomorphs in well “FN O-1” located in the northern part of offshore Kutai Basin. It applies the Planktonic-Benthic Ratio to determine the range of the bathymetric-related environments in the entire depth interval. The aims of this study are to interpret the sequence stratigraphy in the Kutai Basin using small foraminifera and palynomorphs associated with sea level changes. Three sequence stratigraphy phases are identified; TST (Transgressive System Tract), HST (Highstand System Tract), and FSST (Falling Stage System Tract), from the Late Miocene to Pleistocene in an inner to outer neritic environment. The results of the P/B ratio calculation show that wells with a depth of 1,230 feet to 12,180 feet are predominantly located in the inner neritic zone with a ratio percentage less than 20%. The highest abundance of small benthic foraminifera reaching 534 individuals was found at a depth of 1,650 feet within the TST phase. The most abundant planktonic foraminifera (452 individuals) was observed at a depth of 1,350 feet during the TST-HST transition. The FSST revealed the most abundance of mangrove palynomorphs with 100 fossil grains at 11,640 feet and 56 back-mangrove palynomorphs fossils were identified within the TST at 2,340 feet. This study concludes that the abundance of small foraminifera and palynomorphs suggests both marine and terrestrial influences on the basin
GRAVITY MODELING OF SUBSURFACE STRUCTURES AND RESERVOIR CHARACTERIZATION USING SEISMIC INVERSION IN THE NIAS BASIN
Full text linkThe development of interpretation techniques opens new exploration opportunities in the forearc basins of western Indonesia, such as the Nias Basin which show signs of oil and gas seepage. Gravity and seismic inversion analysis were used to look into the Nias Basin in order to evaluate its subsurface structure, the location of sedimentary sub-basins, and the possible presence of hydrocarbon reservoirs. After filtering the data for the Complete Bouguer Anomaly (CBA), a residual anomaly was obtained. This allowed for the quantitative interpretation of structures below the surface using 2D gravity forward modelling. Seismic and well data interpretation includes sensitivity analysis, a well-seismic tie, picking horizons, and acoustic impedance (AI) inversion. The residual gravity anomaly reveals eight sub-basin patterns spread out in the Nias Basin with a relative continuity direction of northwest-southeast following the lineaments of basement highs. The subsurface geological model identified four rock formations. From deepest to shallowest, these units are metamorphic bedrock (2.7 g/cc), Lelematua Formation (2.5 g/cc), Gomo Formation (2.4 g/cc), and Gunungsitoli Formation with an overlying alluvium (2.25 g/cc). Interpretation of well and seismic suggests a target zone at a 2,017 – 2,101 meters depth. Using a model-based hard constraint for AI inversion in this zone indicates possible carbonate reservoirs. Based on sensitivity analysis with an interval of 34,000 - 47,000 (ft/s)*(g/cc), an AI cutoff value of more than 34,000 (ft/s)*(g/cc) was obtained. The carbonate is estimated to be a tight carbonate in the limestone of the Gomo Formation
ANALISIS DATA BATIMETRI MENGGUNAKAN CITRA SATELIT SENTINEL-2 (STUDI KASUS: PULAU PUTRI, BATAM)
Full text linkData batimetri secara konvensional umumnya diperoleh dengan menggunakan teknik echo- sounding yakni dengan instrumen echosounder. Sejumlah masalah atau hambatan dari metode tersebut diantaranya biaya operasional yang mahal, perolehan data tidak multi temporal, kecuali dengan pengukuran ulang. Perkembangan teknologi memungkinkan metode pengukuran batimetri menjadi semakin beragam, salah satu metode alternatifnya adalah menggunakan metode penginderaan jauh dengan memanfaatkan citra satelit atau biasa disebut sattelite derived bathymetry (SDB). Lokasi penelitian ini berada di Pulau Putri, Batam yang dilakukan untuk mengkaji perbandingan data batimetri yang dihasilkan dari citra Sentinel-2 dengan beberapa citra yang diambil pada tanggal berbeda, dengan data pengukuran in situ. Nilai kedalaman dikaji menggunakan metode band ratio dengan memanfaatkan band biru dan hijau. Hasil kedalaman dari Sentinel-2 kemudian dibandingkan berdasarkan nilai Root Mean Square Error (RMSE), koefisien determinasi (R2), dan Total Vertical Uncertainty (TVU). Hasil penelitian ini menunjukkan citra bulan Januari merupakan citra terbaik dengan nilai koefisien determinasi sebesar 0,372. Hasil RMSE menunjukkan semakin tinggi tingkat kesalahan seiring bertambahnya kedalaman. Nilai RMSE pada kedalaman 0 - 30 meter berkisar antara 0,1 - 0,3 meter. Sedangkan pada kedalaman lebih dari 30 meter nilai RMSE bertambah dari 1 - 3 meter. Kualitas SDB dapat diidentifikasi berdasarkan nilai TVU. Berdasarkan analisis pada 8479 titik data insitu masing-masing hanya 645, 318, dan 179 titik data yang terklasifikasi dalam Ordo 2, Ordo 1, dan Ordo spesial
