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INDONESIA
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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Articles 5 Documents
Search results for , issue "Vol 40, No 1 (2025)" : 5 Documents clear
THERMOCLINE WATER TEMPERATURE GRADIENT AT THE INDONESIAN THROUGHFLOW PATHWAYS DURING LAST GLACIAL MAXIMUM (LGM) Rachmayani, Rima; Larasati, Oktavira Dwi Demia; Hendrizan, Marfasran
BULLETIN OF THE MARINE GEOLOGY Vol 40, No 1 (2025)
Publisher : Marine Geological Institute of Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32693/bomg.40.1.2025.937

Abstract

This study aims to investigate the strength of the Indonesian Throughflow (ITF) during the Last Glacial Maximum (LGM) in comparison to the Pre-Industrial (PI) at the Makassar Strait, the Molucca Sea, and the Banda Sea, representing the pathways of the ITF. The analysis was performed based on the temperature distribution of the south (S) and north (N) thermocline gradients. Temperature data were obtained from the simulation of the Climate Community System Model, version 4 (CCSM4). The depth of the thermocline layer during the LGM and the PI period exhibits seasonal variability across the S-N stations. At Station 1, 2, and 3, the thermocline depth during the LGM ranges from 49 - 218 m (51 - 251 m), 55 - 250 m (69 - 254 m), and 48 - 238 m (48 - 218 m) in the south (north), respectively. The analysis of seasonal temperature variations in the thermocline layer in the three locations indicates that the ITF was significantly weakened both during the LGM and PI, indicated by the negative S-N Thermocline Water Temperature (TWT) gradient. The result suggests the southern part of each station is predominantly fresher compared to the northern part during these times. Additionally, it implies that the ITF is more robust in the eastern region (Banda Sea) during the LGM compared to the PI. This variation may relate to the intensity of seasonal local winds, mixing processes, and the remote influence of El Niño-like events, which could affect water transport along the pathway of the ITF.
UPWELLING INFLUENCE ON ENVIRONMENTAL CHANGE AND SEDIMENTATION DYNAMICS FROM TRACE FOSSILS IN THE MOLUCCA SEA: IMPLICATIONS FOR SEDIMENT DATING Wiguna, Taufan; Zuraida, Rina; Atmadipoera, Agus Saleh; Yuwono, Fareza Sasongko; Hernawan, Undang; Christanti, Vera; Tournier, Nicolas; Damanik, Adrianus; Vogel, Hendrik; Cahyarini, Sri Yudawati
BULLETIN OF THE MARINE GEOLOGY Vol 40, No 1 (2025)
Publisher : Marine Geological Institute of Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32693/bomg.40.1.2025.896

Abstract

Bioturbation, the alteration of sediment layers by organism activities, plays a crucial role in shaping sedimentary environments. This process affects nutrient cycling, sediment stability, and habitat health, particularly in marine ecosystems like the Molucca Sea. Bioturbation can complicate age determination by disrupting the natural layering of sediments and potentially altering chronological records, which challenges the accuracy of dating methods. This study investigates bioturbation patterns and Zr/Rb ratios in sediment cores from the Molucca Sea to better understand past environmental conditions and assess the suitability of these sediments for age determination. Sediment samples were collected using a box corer from BUDEE22-29BC (within the upwelling region) and BUDEE22-57BC (outside the upwelling area). The cores were analyzed using CT scanning to identify bioturbation features, and the Bioturbation Index (BI) was applied to evaluate the intensity and impact of bioturbation on sediment dynamics. The Zr/Rb ratios were determined using an X-ray fluorescence (XRF) spectrometer, providing insights into grain size distribution. The results suggest the potential shifting of the upwelling center (BUDEE22-29BC) and variations in upwelling intensity (BUDEE22-57BC). Although Zr/Rb ratio shows that BUDEE22-29BC is a high-energy environment, as opposed to BUDEE22-57BC, both sites retain chronological integrity, making them suitable for paleoenvironmental and geochronological analysis.
BEARING CAPACITY AND SETTLEMENT BEHAVIOUR OF COASTAL SOIL FOR THE PLANNED BALONGAN PORT DEVELOPMENT, WEST JAVA Ekasara, Adam Raka; Raharjo, Purnomo; Susilowati, Susilowati
BULLETIN OF THE MARINE GEOLOGY Vol 40, No 1 (2025)
Publisher : Marine Geological Institute of Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32693/bomg.40.1.2025.943

Abstract

The planned development of Balongan Port in West Java requires a comprehensive geotechnical evaluation to support foundation planning at the proposed site, which is underlain by soft, clay-rich sediments. This study aims to assess the bearing capacity of the subsurface and predict potential settlement behaviour by integrating field and laboratory investigations. Standard Penetration Test (SPT) data from two boreholes, BH-3 (14 m) and BH-4 (18 m), and were complemented by laboratory analyses of soil physical and mechanical properties. The site is primarily composed of high-plasticity clay, known for its low strength, high compressibility, and variable geotechnical characteristics. Calculations based on SPT results yielded allowable loads of 53.1 tons at BH-3 and 39.0 tons at BH-4, respectively, while laboratory analyses indicated significantly higher bearing capacities of 265.9 tons and 884.4 tons, respectively. Settlement predictions based on SPT and laboratory data were 0.61 cm and 2.07 cm, with an estimated 90% consolidation period of about 12.9 years. These findings emphasize the variability and compressibility of the soft clay strata as well as the importance of employing multiple assessment methods. The study provides essential input for foundation planning and highlights the need for integrated geotechnical assessment methods to ensure the safety, reliability, and long-term performance of pile-supported structures at the proposed port site.
STUDY OF HEAVY METAL LEAD (PB) IN THE NORTHERN WATERS OF BELITUNG REGENCY Fathona, Salsabila; Rachmayani, Rima; Nurhidayati, Ayu Utami; Utami, Dwi Amanda
BULLETIN OF THE MARINE GEOLOGY Vol 40, No 1 (2025)
Publisher : Marine Geological Institute of Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32693/bomg.40.1.2025.860

Abstract

Belitung Regency has significant tin potential, spread across the land, rivers, and beaches which have been mined for hundreds of years. However, tin mining activities are indicated to be a source of pollution in the northern region of Belitung Regency. This study aims to determine the distribution of the lead (Pb) concentrations in sediments and water columns in the northern waters of Belitung Regency and to evaluate the seasonal effect, particularly ocean currents, on the distribution patterns. In situ data were collected during the westerly season, including sediment samples, water column samples, and oceanographic parameters such as seawater quality and current measurements. During the easterly season, only sediment samples were obtained. Pb concentrations in sediments and water samples were analyzed at the National Research and Innovation Agency (BRIN) laboratory using the Atomic Absorption Spectrophotometry (AAS) method. The results showed that Pb concentrations in sediment samples ranged from 10.08 to 50.08 mg/kg during the easterly season, and from 10.96 to 60.72 mg/kg during the westerly season. In the water column, Pb concentrations ranged from 0 to 0.05 mg/L during the westerly season. The distribution pattern of Pb in sediments in the easterly season tended to spread offshore, while in the westerly season it is accumulated in the river. These patterns are influenced by seasonal flow variations, geographical location, and sediment grain size. Pb concentrations in sediments are higher in the westerly season compared to the easterly season. This is likely due to increased erosion and surface runoff during the rainy season, which leads to greater deposition of heavy metals in marine sediments.
IMPACT OF SIGNIFICANT WAVE HEIGHT, WIND SPEED, AND PRECIPITATION VARIABILITY ON SHIPPING SAFETY IN INDONESIAN ARCHIPELAGIC SEA LANES Fathurohman, Azkal; Napitupulu, Gandhi; Fujiawati, Ghina; Napitupulu, Moses
BULLETIN OF THE MARINE GEOLOGY Vol 40, No 1 (2025)
Publisher : Marine Geological Institute of Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32693/bomg.40.1.2025.895

Abstract

Unexpected and unpredictable extreme weather poses significant risks to maritime activities, particularly in Indonesian waters and the Indonesian Archipelagic Sea Lanes, known as ALKI, which have been internationally recognized for shipping and aviation since 1985. This study assesses these risks by analyzing patterns of wave height, wind speed, and rainfall along ALKI to improve shipping safety and mitigate accident risks. Data from the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA5 for the period 1993 to 2023 and Global Precipitation Measurement (GPM) for 2001 to 2020 were processed using descriptive statistics and Empirical Orthogonal Function (EOF) methods. The results reveal high waves (1-2.5 m) and strong winds at Beaufort scale 4 prevailing in northern Indonesian waters from December to February and southern waters from June to August. Higher rainfall (350-600 mm) occurs in the northern region from September to November and in the southern from December to February. Extreme waves (90th percentile) reach up to 3 m in open ocean areas such as the Natuna Sea, western Sumatra, southern Java, the Maluku Sea, and northern Papua Sea. Extreme winds are observed over open ocean areas, with slight spatial shifts, as seen in the Arafura Sea (9-10 m/s). Extreme rainfall (250-350 mm) is concentrated in the northwestern region. EOF analysis identifies global climate phenomena and regional oceanographic dynamics as the primary drivers of significant wave height variability. Improved understanding of weather variability can enhance navigation safety along the ALKI routes and inform more effective regulation, law enforcement, and monitoring.

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