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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.
Arjuna Subject : -
Articles 173 Documents
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.