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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 180 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.
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.
IDENTIFICATION OF EARTHQUAKE AND TSUNAMI RISK ZONES IN SOUTHERN JAVA USING GRAVITY METHOD Karima, Isna; Martha, Agustya Adi; Hudayat, Nurul; Zera, Tati
BULLETIN OF THE MARINE GEOLOGY Vol 40, No 2 (2025)
Publisher : Marine Geological Institute of Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32693/bomg.40.2.2025.934

Abstract

The southern part of Java has a high level of disaster risk because it is affected by a subduction zone where the Indo-Australian plate thrusts beneath the Eurasian plate. Six tsunami events occurred in the southern part of Java, caused by earthquakes in the area, based on BMKG catalogue data from 416 to 2023. Given the very large population on the island of Java, the possibility of causing more casualties is greater. Therefore, it is very necessary to have thorough mitigation preparation to estimate the possibility of areas experiencing a large earthquake that triggers a tsunami. This study aims to determine areas with a high level of earthquake and tsunami risk distribution using the gravity method with data from the TOPEX satellite in the form of free air anomaly data and topographic data. After data processing and an anomaly map were obtained, it showed that areas with a high level of earthquake risk were located around the subduction zone and Java Trench. This is due to the geological conditions of the southern part of Java, located in the subduction zone where many active faults were found.
GEOCHEMISTRY OF SEABED AND COASTAL SEDIMENTS IN LIMAU WATERS AREA Zulfikar, Muhammad; Saputro, Eko; Albab, Ali; Rahardiawan, Riza
BULLETIN OF THE MARINE GEOLOGY Vol 40, No 2 (2025)
Publisher : Marine Geological Institute of Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32693/bomg.40.2.2025.953

Abstract

Sediment provenance and weathering history are used to understand sedimentary processes and to explore mineral potential in coastal–marine systems in the Limau Waters. Therefore, the characteristics of seabed and coastal sediments need to be determined. This study aims to identify the source rocks, paleoweathering signatures, and sediment maturity of both seabed and coastal sediments through a geochemical approach. A geochemical approach that integrates major oxide and rare earth element (REE) analyses, the paleoweathering, and sediment maturity indices, is used to identify the source rocks of these sediments. Major oxides elements were measured using X-ray fluorescence (XRF) and REE concentrations were determined using inductively coupled plasma - optical emission spectrometry (ICP-OES) and inductively coupled plasma optical - mass spectrometry (ICP-MS). Geochemical discrimination diagrams indicate that seabed sediments are mainly derived from intermediate to felsic igneous rocks with higher compositional maturity, whereas coastal sediments are influenced by mafic volcanic rocks and are comparatively immature in composition. Both sediment types exhibit weak chemical weathering (CIA < 70), suggesting limited alteration of young volcanic sources. The CIA–ICV relationships portray contrast sediment transport and depositional processes between the coastal and marine environments. This study is expected to provide a geochemical-based framework for provenance analysis and to support the development of insights for future marine mineral exploration in the Limau Waters area.
FORAMINIFERA DISTRIBUTION AS AN INDICATOR OF PALEOCEANOGRAPHY IN WAIPOGA WATERS, NORTHERN PAPUA Wijaya, Joleen Felicia; Jatiningrum, Resti Samyati; Gustiantini, Luli; Putri, Mardhatillah Kurnia; Firdaus, Yulinar
BULLETIN OF THE MARINE GEOLOGY Vol 40, No 2 (2025)
Publisher : Marine Geological Institute of Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32693/bomg.40.2.2025.965

Abstract

Foraminifera are widely used as indicators for reconstructing past marine environmental conditions. This study aims to investigate the ecological conditions of Waipoga waters, North Papua, by analyzing the distribution of foraminifera during the late Middle Holocene to Late Holocene. The study area plays an important role in the dynamics of the Indonesian Throughflow (ITF/ITF) and ENSO. Sediment core samples were prepared and identified for foraminifera, followed by quantitative analyses including relative abundance, P/B ratio, and ecological indices. In addition, sortable silt analysis was applied as an environmental proxy to support the reconstruction of past environmental changes. The results show that foraminiferal abundance throughout the sediment core varies. Planktonic foraminifera are more dominant, comprising 12 genera with 22 species. The most dominant species are Globigerinoides ruber (41,7%), Neogloboquadrina dutertrei (11%), Neogloboquadrina incompta (13,2%), Pulleniatina obliquiloculata (4%), Hastigerina pelagica (6,65%), and Globigerinoides immaturus (6,7%). Meanwhile, benthic foraminifera consist of 42 genera with 62 species, dominated by Bulimina marginata (1,8%), Cibicidoides pachyderma (1,89%), and Lenticulina calcar (1,3%). During the late Middle Holocene to Late Holocene, the Waipoga waters were influenced by variations in bottom current intensity and thermocline stability. Zones I and III reflect oligotrophic conditions with weak circulation, while Zone II indicates increased bottom current intensity, high productivity, and dysoxic conditions, suggesting possible intensification of upwelling events.
HYDROCARBON POTENTIAL OF THE OFFSHORE AKIMEUGAH BASIN FROM MESOZOIC-PALEOZOIC BASED ON GEOLOGICAL AND GEOPHYSICAL ANALYSIS Setiadi, Imam; Rasyid, Faris N; Zulivandama, Shaska Ramadhan; Firdaus, Yulinar; Santy, Lauty D.; Saleh, Hanif M.; Rachman, Muhammad G.; Djaja, Andrian W.; Nurdin, Nazar; Rahardiawan, Riza; Subarsyah, Subarsyah
BULLETIN OF THE MARINE GEOLOGY Vol 40, No 2 (2025)
Publisher : Marine Geological Institute of Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32693/bomg.40.2.2025.954

Abstract

Akimeugah Basin is one of the basins with discovery status, however hydrocarbon production has not yet been established. One of potential petroleum play type for further investigation, estimated to contain hydrocarbon reserves in the offshore Akimeugah Basin, is the Mesozoic–Paleozoic sedimentary play, interpreted to have originated from the Australian passive margin. This study aims to analyze geological and geophysical data to delineate the sub-basin pattern and characterize petroleum system elements. The analysis integrates gravity data interpretation, geochemical evaluation of source rocks, and subsurface interpretation based on seismic and well data. Results indicate that source rocks in the Kola-1 well are primarily composed of Type III (gas-prone) and secondarily of Type II (oil/gas-prone) kerogen. Thermal maturity analysis shows that the Woniwogi, Aiduna, and Modio Formations have reached the oil window. Reservoir potential has been identified in the Tipuma Formation (Triassic), Aiduna Formation (Permian), and Modio Dolomite (Devonian–Silurian). Seal rocks consist of regional and intraformational units composed of tight siltstone and shale. Trapping mechanisms in this area include a combination of structural traps such as fault-bounded anticlines and stratigraphic traps represented by sub-unconformities. Identified exploration leads include seven within the Modio Dolomite structural play, six within the Permian Aiduna Sandstone play, and four within the Triassic Tipuma Sandstone play.
ACOUSTIC FACIES AROUND THE INTRUSIVE COMPLEX OF SALAHNAMA AND PANDANG ISLANDS, MALACCA STRAIT , S.Si., MT., Subarsyah; Albab, Ali; Zulivandama, Shaska Ramdhan; Saputro, Eko; Ali, Arif; Setiadi, Imam; Zulfikar, Muhammad; Nauval, Faris; Rahardiawan, Riza
BULLETIN OF THE MARINE GEOLOGY Vol 40, No 2 (2025)
Publisher : Marine Geological Institute of Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32693/bomg.40.2.2025.938

Abstract

Salahnama and Pandang Islands lie on the main range of the granite province; both islands are located in the Sunda Shelf, Malacca Straits. These islands are composed of intrusive rocks from Berhala. The rock’s existence will offer a significant contribution to the distribution of surface sediments in the surroundings. The sea dynamics and the geometry of the Malacca Strait will also have an impact on the seabed. Apart from that, global factors such as sea level changes will lead to transformation of the depositional environment and subsurface geology in the strait. Geological conditions of the seabed surface and subsurface can be understood and interpreted based on the acoustic characteristics and reflector patterns of a seismic section. Then, based on the acoustic character and reflector pattern, an acoustic facies can be defined. Seismic data measurements have been carried out around Salahnama and Pandang Islands in 2024. Based on the results of the seismic section, the acoustic facies in the study area are classified into 6 (six), which include AF I – AF VI. Seabed morphological features in the form of sand dunes were identified in the first acoustic facies (AF I); this feature is formed due to geometric aspects, surface currents, and bottom current's which may or may not be triggered by tidal vortices. Acoustic Facies II (AF II) is characterized by sandwave or ripple marks formed by strong seabed currents. AF III was formed after the Last Glacial Maximum (LGM) ended and the depositional environment returned to a shallow marine environment, characterized by a transparent pattern in the seismic section. The erosional truncation at the upper boundary of AF IV indicates a change in the depositional environment from shallow marine to coastal or terrestrial environments during the Last Glacial Maximum period. AF V is acoustic bedrock, and AF VI is characterized by a chaotic pattern, which is interpreted as granitic intrusive rocks.