Pub Date : 2025-11-19DOI: 10.1016/j.margeo.2025.107679
Matteo Meli , Enrica Vecchi , Claudia Romagnoli
This study aims to reconstruct and analyze shoreline evolution along the highly urbanized Emilia-Romagna coast (Italy) over the period 1984–2023 using satellite-derived shorelines. Landsat and Sentinel-2 imagery were processed with the CoastSat toolbox, and shoreline positions were corrected for tide and wave setup before deriving yearly averages from 2,200 transects. While the spatial resolution of yearly-averaged SDS is lower than that of conventional techniques, this approach enables, for the first time in this region, the reconstruction of shoreline dynamics as a continuous time series spanning interannual to multi-decadal scales. Results highlight substantial spatial and temporal variability across the shoreline, driven by the interplay of natural processes and anthropogenic interventions such as coastal defenses, repeated nourishments, and sediment extraction. Despite ongoing sea-level rise and subsidence, most of the coast exhibits stability or net advancement, largely maintained through human interventions. The resulting dataset provides one of the most temporally extensive records of shoreline variability for the Emilia-Romagna coast and represents a valid basis for future monitoring and coastal management.
{"title":"Shoreline evolution in a low-lying coastal region under anthropogenic influence","authors":"Matteo Meli , Enrica Vecchi , Claudia Romagnoli","doi":"10.1016/j.margeo.2025.107679","DOIUrl":"10.1016/j.margeo.2025.107679","url":null,"abstract":"<div><div>This study aims to reconstruct and analyze shoreline evolution along the highly urbanized Emilia-Romagna coast (Italy) over the period 1984–2023 using satellite-derived shorelines. Landsat and Sentinel-2 imagery were processed with the CoastSat toolbox, and shoreline positions were corrected for tide and wave setup before deriving yearly averages from 2,200 transects. While the spatial resolution of yearly-averaged SDS is lower than that of conventional techniques, this approach enables, for the first time in this region, the reconstruction of shoreline dynamics as a continuous time series spanning interannual to multi-decadal scales. Results highlight substantial spatial and temporal variability across the shoreline, driven by the interplay of natural processes and anthropogenic interventions such as coastal defenses, repeated nourishments, and sediment extraction. Despite ongoing sea-level rise and subsidence, most of the coast exhibits stability or net advancement, largely maintained through human interventions. The resulting dataset provides one of the most temporally extensive records of shoreline variability for the Emilia-Romagna coast and represents a valid basis for future monitoring and coastal management.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"492 ","pages":"Article 107679"},"PeriodicalIF":2.2,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145623006","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Grain size distribution patterns of the Bay of Bengal marine sediments have the potential to provide valuable insights into the long-term variability of the Indian Summer Monsoon (ISM). The study presents a Plio-Pleistocene marine sediment grain size record from the offshore Mahanadi Basin to decipher precipitation phases and reconstruct long-term ISM variability. We have analysed the grain size distribution of 150 marine sediment core samples recovered from the Hole NGHP-01-19A in the western Bay of Bengal, covering the Plio-Pleistocene interval. Through the application of end-member Modelling Analysis of grain size distribution, the study identifies key sediment transport modes and infers monsoon-influenced depositional changes. Three dominant end-members (EM1, EM2, and EM3) were identified, with the majority (∼ 96 %) of sediments falling within the silt-size range. The temporal distribution of EM3, sand (%), and mean grain size reveals the intensified monsoon precipitation phases between 5.3 Ma – 5.2 Ma, 4.6 Ma - 3.2 Ma, at 2.7 Ma, 1.4 Ma - 1.2 Ma and 0.8 Ma - Recent. These observations are validated using published monsoonal proxies [Runoff data (IODP U1445 and U1446), Uvigerina proboscidea abundance and δ18O of Planktic foraminifera (ODP 758)]. The spectral and continuous wavelet transformation of EM3 and sand (%) indicates a strong influence of orbital forcing during the entire Pliocene epoch on the ISM precipitation phases. These findings highlight the close connection between monsoonal variability, orbital forcing, and sediment delivery to the western Bay of Bengal.
孟加拉湾海洋沉积物的粒度分布模式有可能为印度夏季风（ISM）的长期变化提供有价值的见解。本文利用Mahanadi盆地上新世-更新世海相沉积粒度记录，对降水阶段进行了解析，重建了ISM的长期变化。本文分析了孟加拉湾西部NGHP-01-19A孔150个海相沉积物岩心样品的粒度分布，样品覆盖了上新世-更新世区间。通过对粒度分布的端元模拟分析，确定了关键的输沙模式，推断了受季风影响的沉积变化。确定了三个主要的端元（EM1， EM2和EM3），大多数（~ 96%）的沉积物落在粉砂粒度范围内。EM3、沙粒（%）和平均粒径的时间分布揭示了5.3 Ma ~ 5.2 Ma、4.6 Ma ~ 3.2 Ma、2.7 Ma、1.4 Ma ~ 1.2 Ma和0.8 Ma ~近期的季风降水增强阶段。这些观测结果通过已公布的季风代用物[径流数据（IODP U1445和U1446）、长形假水蛭丰度和浮游有孔虫的δ18O (ODP 758)]得到了验证。EM3和沙（%）的光谱和连续小波变换表明，整个上新世的轨道强迫对ISM降水阶段有很强的影响。这些发现强调了季风变率、轨道强迫和向孟加拉湾西部输送沉积物之间的密切联系。
{"title":"Plio-pleistocene sediment grain size variability in the Western Bay of Bengal: Evidences of Indian Summer Monsoon intensification","authors":"Nitika Millicent Patrick, Nishant Vats , Ajoy K. Bhaumik, Satabdi Mohanty, Koustav Chattopadhyay","doi":"10.1016/j.margeo.2025.107682","DOIUrl":"10.1016/j.margeo.2025.107682","url":null,"abstract":"<div><div>Grain size distribution patterns of the Bay of Bengal marine sediments have the potential to provide valuable insights into the long-term variability of the Indian Summer Monsoon (ISM). The study presents a Plio-Pleistocene marine sediment grain size record from the offshore Mahanadi Basin to decipher precipitation phases and reconstruct long-term ISM variability. We have analysed the grain size distribution of 150 marine sediment core samples recovered from the Hole NGHP-01-19A in the western Bay of Bengal, covering the Plio-Pleistocene interval. Through the application of end-member Modelling Analysis of grain size distribution, the study identifies key sediment transport modes and infers monsoon-influenced depositional changes. Three dominant end-members (EM1, EM2, and EM3) were identified, with the majority (∼ 96 %) of sediments falling within the silt-size range. The temporal distribution of EM3, sand (%), and mean grain size reveals the intensified monsoon precipitation phases between 5.3 Ma – 5.2 Ma, 4.6 Ma - 3.2 Ma, at 2.7 Ma, 1.4 Ma - 1.2 Ma and 0.8 Ma - Recent. These observations are validated using published monsoonal proxies [Runoff data (IODP U1445 and U1446), <em>Uvigerina proboscidea</em> abundance and δ<sup>18</sup>O of Planktic foraminifera (ODP 758)]. The spectral and continuous wavelet transformation of EM3 and sand (%) indicates a strong influence of orbital forcing during the entire Pliocene epoch on the ISM precipitation phases. These findings highlight the close connection between monsoonal variability, orbital forcing, and sediment delivery to the western Bay of Bengal.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"491 ","pages":"Article 107682"},"PeriodicalIF":2.2,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145576506","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-18DOI: 10.1016/j.margeo.2025.107681
Wenjun Zeng , Zhijun Dai , Jiejun Luo , Yi Chen , Xiaowen Xie , Riming Wang
Mangrove wetlands play a vital role in reducing water flow and wave energy, facilitating sediment capture and accumulation, thereby stabilizing coastlines and protecting coastal zones. Nevertheless, few studies have comprehensively investigated the hydrodynamic and sedimentary processes from bare flat zone to the forest interior of mangrove wetlands. Therefore, this study collected comprehensive field data, including hydrological, sediment, and elevation measurements between 2020 and 2022, aiming to diagnosing the attenuation of hydrodynamic and sediment processes in an undisturbed mangrove wetland of the Nanliu River Estuary. Results showed both current velocity and wave height declined markedly landward, accompanied by spatial fluctuations. Specifically, mean flood velocity, mean ebb velocity, and mean significant wave height decreased by over 70 %, 40 %, and 50 %, respectively. Correspondingly, surface sediments showed a general fining trend landward, with localized variations reflecting spatial heterogeneity of hydrodynamic forces. Meanwhile, surface elevation in bare flat zone increased sharply landward at an average slope of 1.6 ‰, while vegetated zone displayed a much gentler profile, averaging around 0.3 m. Vegetated zone was in relatively stable state, typically undergoing weak erosion or strong accretion, whereas bare flat zone experienced pronounced erosion or minor deposition. Dense, mature mangroves could effectively dissipate wave energy and slowing tidal currents, reducing flood velocity, ebb velocity, and wave height by 0.42 %/m, 0.25 %/m, and 0.45 %/m, respectively. Typhoons not only triggered substantial erosion but also reshaped sediment characteristics, with their impacts modulated by water depth controlled by tidal cycle variations.
{"title":"Hydro-sedimentary processes of mangrove wetland over a meso-macrotidal estuary","authors":"Wenjun Zeng , Zhijun Dai , Jiejun Luo , Yi Chen , Xiaowen Xie , Riming Wang","doi":"10.1016/j.margeo.2025.107681","DOIUrl":"10.1016/j.margeo.2025.107681","url":null,"abstract":"<div><div>Mangrove wetlands play a vital role in reducing water flow and wave energy, facilitating sediment capture and accumulation, thereby stabilizing coastlines and protecting coastal zones. Nevertheless, few studies have comprehensively investigated the hydrodynamic and sedimentary processes from bare flat zone to the forest interior of mangrove wetlands. Therefore, this study collected comprehensive field data, including hydrological, sediment, and elevation measurements between 2020 and 2022, aiming to diagnosing the attenuation of hydrodynamic and sediment processes in an undisturbed mangrove wetland of the Nanliu River Estuary. Results showed both current velocity and wave height declined markedly landward, accompanied by spatial fluctuations. Specifically, mean flood velocity, mean ebb velocity, and mean significant wave height decreased by over 70 %, 40 %, and 50 %, respectively. Correspondingly, surface sediments showed a general fining trend landward, with localized variations reflecting spatial heterogeneity of hydrodynamic forces. Meanwhile, surface elevation in bare flat zone increased sharply landward at an average slope of 1.6 ‰, while vegetated zone displayed a much gentler profile, averaging around 0.3 m. Vegetated zone was in relatively stable state, typically undergoing weak erosion or strong accretion, whereas bare flat zone experienced pronounced erosion or minor deposition. Dense, mature mangroves could effectively dissipate wave energy and slowing tidal currents, reducing flood velocity, ebb velocity, and wave height by 0.42 %/m, 0.25 %/m, and 0.45 %/m, respectively. Typhoons not only triggered substantial erosion but also reshaped sediment characteristics, with their impacts modulated by water depth controlled by tidal cycle variations.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"491 ","pages":"Article 107681"},"PeriodicalIF":2.2,"publicationDate":"2025-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145576505","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-05DOI: 10.1016/j.margeo.2025.107680
Muhedeen A. Lawal, Ann E. Cook, Derek E. Sawyer
Offshore mud volcanoes can be sites of energetic eruptions and flank collapse. Using three dimensional seismic data from the Gulf of Mexico, we reveal an extensive mass flow (>1.1 × 109 m3) that is linked to one of the region's largest and active mud volcanoes, the Kohl mud volcano. Our analysis reveals a collapsed southeastern crater flank that is ∼1300 m wide and marked by collapse scarps at Kohl. The resulting mass flow is characterized by basin-verging (∼16°) toe thrusts, widens downslope, and ends abruptly at a moat on the seafloor. Unlike typical thin, less cohesive mud volcano flows, this deposit is ∼100 m thick, extends ∼6000 m downslope, and originates from the failed southeastern flank. The deposit is bound by kilometer-scale faults that connect the collapse scarp upslope at the mud volcano crater, and exhibits localized erosion below its debris tongue, typical of mass transport deposits. Erosive and compressional behaviors define the terminal phase of the mass flow emplacement and likely reflect an energetic emplacement event. We argue that an energetic eruption and subsequent crater rim and flank collapse provides the most plausible explanation for our observations, highlighting the feedback between submarine mud volcanism and mass wasting. This study represents an important step forward for understanding how submarine mud volcanism influences the formation of thick and erosive mass flows and the processes that govern the emplacement of such flows on seafloors globally.
{"title":"A submarine mud volcano eruption triggered a 100 m thick mass flow","authors":"Muhedeen A. Lawal, Ann E. Cook, Derek E. Sawyer","doi":"10.1016/j.margeo.2025.107680","DOIUrl":"10.1016/j.margeo.2025.107680","url":null,"abstract":"<div><div>Offshore mud volcanoes can be sites of energetic eruptions and flank collapse. Using three dimensional seismic data from the Gulf of Mexico, we reveal an extensive mass flow (>1.1 × 10<sup>9</sup> m<sup>3</sup>) that is linked to one of the region's largest and active mud volcanoes, the Kohl mud volcano. Our analysis reveals a collapsed southeastern crater flank that is ∼1300 m wide and marked by collapse scarps at Kohl. The resulting mass flow is characterized by basin-verging (∼16°) toe thrusts, widens downslope, and ends abruptly at a moat on the seafloor. Unlike typical thin, less cohesive mud volcano flows, this deposit is ∼100 m thick, extends ∼6000 m downslope, and originates from the failed southeastern flank. The deposit is bound by kilometer-scale faults that connect the collapse scarp upslope at the mud volcano crater, and exhibits localized erosion below its debris tongue, typical of mass transport deposits. Erosive and compressional behaviors define the terminal phase of the mass flow emplacement and likely reflect an energetic emplacement event. We argue that an energetic eruption and subsequent crater rim and flank collapse provides the most plausible explanation for our observations, highlighting the feedback between submarine mud volcanism and mass wasting. This study represents an important step forward for understanding how submarine mud volcanism influences the formation of thick and erosive mass flows and the processes that govern the emplacement of such flows on seafloors globally.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"491 ","pages":"Article 107680"},"PeriodicalIF":2.2,"publicationDate":"2025-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145526044","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-02DOI: 10.1016/j.margeo.2025.107678
Sebastian Lindhorst , Linus Budke , Robin J. Beaman , Jan Oliver Eisermann , Christian Hübscher , Niko Lahajnar , Thomas Lüdmann , Jody M. Webster , Christian Betzler
Sediment conduits like erosive canyons and channels are common morphological elements of submarine landscapes down to abyssal depths. While canyon-channel systems connected to slopes and shallow water are well studied, detached sediment-routing systems emerging in deeper waters have received less attention, especially in carbonate settings. We study the sedimentary architecture and evolution of an extensive canyon-channel system in the ‘Willis Passage’, a marine strait between the Magdelaine and Willis carbonate banks (Queensland Plateau, northeast Australia). The canyon-channel system is detached from the slopes of the carbonate banks, emerges at depths of >500 m and runs over more than 100 km towards the slope break of the carbonate plateau. The canyon is several kilometres wide and several tens of metres deep. Morphological edges (knickpoints) occur along the canyon course; one with a plunge pool at its downstream foot wall. Current ripples and coarse-grained lag deposits at the floor of the canyon indicate bottom-current activity and possibly winnowing of fine-grained sediment. The seafloor outside the canyon is intersected by bundles of grooves (linear seafloor cuts), tens of kilometres long. Sedimentological and morphological characteristics indicate that canyon-channel system and grooves are shaped by eastward-flowing bottom currents, which is in a direction counter to the dominant westward-flowing oceanic current regime. We propose that eastward-flowing sediment-laden bottom currents originate from the channelization of oceanic currents by the carbonate edifices of the Queensland Plateau, paired with tidal pumping in the narrow passages between the banks. This mechanism is most efficient during episodes of lowered sea level, while bottom currents are much weaker during sea-level highstand. Our seismic data reveal the existence of buried individual canyon-channel systems and document that the Queensland Plateau underwent episodic changes in the local current regime since the upper Miocene. Based on new geophysical and oceanographic data, as well as video observations of the seafloor, we show that slope-detached deep-water canyon-channel systems act as a conveyor, routing sediment from carbonate platforms to the deep ocean. As a link between the neritic realm and abyssal depths, these systems are important agents of dismantling and degradation of carbonate platforms and underline the role of bottom currents in shaping these depositional environments.
{"title":"Deep-water canyon-channel systems of the Queensland Plateau, Northeast Australia","authors":"Sebastian Lindhorst , Linus Budke , Robin J. Beaman , Jan Oliver Eisermann , Christian Hübscher , Niko Lahajnar , Thomas Lüdmann , Jody M. Webster , Christian Betzler","doi":"10.1016/j.margeo.2025.107678","DOIUrl":"10.1016/j.margeo.2025.107678","url":null,"abstract":"<div><div>Sediment conduits like erosive canyons and channels are common morphological elements of submarine landscapes down to abyssal depths. While canyon-channel systems connected to slopes and shallow water are well studied, detached sediment-routing systems emerging in deeper waters have received less attention, especially in carbonate settings. We study the sedimentary architecture and evolution of an extensive canyon-channel system in the ‘Willis Passage’, a marine strait between the Magdelaine and Willis carbonate banks (Queensland Plateau, northeast Australia). The canyon-channel system is detached from the slopes of the carbonate banks, emerges at depths of >500 m and runs over more than 100 km towards the slope break of the carbonate plateau. The canyon is several kilometres wide and several tens of metres deep. Morphological edges (knickpoints) occur along the canyon course; one with a plunge pool at its downstream foot wall. Current ripples and coarse-grained lag deposits at the floor of the canyon indicate bottom-current activity and possibly winnowing of fine-grained sediment. The seafloor outside the canyon is intersected by bundles of grooves (linear seafloor cuts), tens of kilometres long. Sedimentological and morphological characteristics indicate that canyon-channel system and grooves are shaped by eastward-flowing bottom currents, which is in a direction counter to the dominant westward-flowing oceanic current regime. We propose that eastward-flowing sediment-laden bottom currents originate from the channelization of oceanic currents by the carbonate edifices of the Queensland Plateau, paired with tidal pumping in the narrow passages between the banks. This mechanism is most efficient during episodes of lowered sea level, while bottom currents are much weaker during sea-level highstand. Our seismic data reveal the existence of buried individual canyon-channel systems and document that the Queensland Plateau underwent episodic changes in the local current regime since the upper Miocene. Based on new geophysical and oceanographic data, as well as video observations of the seafloor, we show that slope-detached deep-water canyon-channel systems act as a conveyor, routing sediment from carbonate platforms to the deep ocean. As a link between the neritic realm and abyssal depths, these systems are important agents of dismantling and degradation of carbonate platforms and underline the role of bottom currents in shaping these depositional environments.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"491 ","pages":"Article 107678"},"PeriodicalIF":2.2,"publicationDate":"2025-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145474756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bed roughness affects the turbulence structure within the bottom boundary layer (BBL), thus playing a significant role in sediment resuspension and transport. This study collected in-situ turbulence and sediment data within the BBL of the Pearl River Estuary (PRE) using a benthic quadrapod observation system. Based on quadrant analysis results, the presence of ripples leads to increased bed roughness, which enhances ejections and sweeps. We also find that sweep and ejection events possess stronger sediment mobilization capacity and higher transport efficiency, rather than simply having a larger time proportion. Additionally, under low bed shear stress, the presence of a fluffy layer makes the contribution of inward interactions to sediment flux during flood tide particularly significant. Consequently, we improved the method for determining the waiting time of the sediment flux intermittency index to identify the erosion of consolidated sediment layers.
{"title":"Impact of fluffy layer and bedform on turbulent intermittency in tidally induced bottom boundary layer","authors":"Zhixin Cao, Chao Li, Zhenkun Lin, Yaokun Lin, Zhaohui Deng, Jiaxue Wu, Jie Ren","doi":"10.1016/j.margeo.2025.107677","DOIUrl":"10.1016/j.margeo.2025.107677","url":null,"abstract":"<div><div>Bed roughness affects the turbulence structure within the bottom boundary layer (BBL), thus playing a significant role in sediment resuspension and transport. This study collected in-situ turbulence and sediment data within the BBL of the Pearl River Estuary (PRE) using a benthic quadrapod observation system. Based on quadrant analysis results, the presence of ripples leads to increased bed roughness, which enhances ejections and sweeps. We also find that sweep and ejection events possess stronger sediment mobilization capacity and higher transport efficiency, rather than simply having a larger time proportion. Additionally, under low bed shear stress, the presence of a fluffy layer makes the contribution of inward interactions to sediment flux during flood tide particularly significant. Consequently, we improved the method for determining the waiting time of the sediment flux intermittency index to identify the erosion of consolidated sediment layers.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"491 ","pages":"Article 107677"},"PeriodicalIF":2.2,"publicationDate":"2025-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145474754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-28DOI: 10.1016/j.margeo.2025.107676
Z.A. Roseby , T. Sengupta , S.L. Ward , D.F. Vosper , M. Blaauw , C.M. Roberts , J.D. Scourse
Continental shelf sediments – particularly soft, muddy habitats - serve as significant reservoirs of organic carbon over glacial-interglacial timescales and are subject to disturbance, notably from mobile bottom fishing gear. The quantity and quality of accumulated organic carbon varies across shelf environments, with muds storing more organic carbon than other substrate types. For effective marine management, it has been recommended that the reactivity, or ‘quality’, of organic matter should be considered when assessing the vulnerability of sedimentary carbon to disturbance. If management interventions are to be made to protect vulnerable organic carbon reservoirs on the seafloor, then it is also important to consider the burial efficiency of carbon. In areas of rapid sediment accumulation, carbon will be moved from surface to geological reservoirs more quickly, thus facilitating carbon sequestration. In this study, we assess the quantity, quality, and accumulation rate of organic carbon in the muddy depocenter of the Fladen Ground, northern North Sea - an area of low active sediment accumulation, with both historic and ongoing bottom trawling. All sediment cores analysed in this study display upwards coarsening of surface sediments, consistent with sediment disturbance and winnowing. Southern Fladen Ground sediments are especially well sorted, depleted in total organic carbon, and enriched in calcium carbonate - patterns that align with intensified trawling. Our results show very low modern organic carbon accumulation rates (∼0.7 g C m−2 yr−1), low organic matter reactivity (18.5 % labile), and that modern trawl events can potentially disturb sediments and carbon accumulated over the last ∼2300 years. These results indicate that sediment and organic carbon accumulation rates are an important consideration when assessing the vulnerability of sedimentary carbon.
大陆架沉积物——尤其是软质、泥泞的栖息地——在冰期-间冰期时间尺度上是有机碳的重要储存库，并容易受到干扰，尤其是来自移动式底部渔具的干扰。累积有机碳的数量和质量因陆架环境而异，淤泥比其他类型的基质储存更多的有机碳。为了有效地管理海洋，有人建议在评估沉积碳对干扰的脆弱性时应考虑有机物的反应性或“质量”。如果要采取管理干预措施来保护海底脆弱的有机碳储层，那么考虑碳的埋藏效率也很重要。在沉积物积聚迅速的地区，碳将更快地从地表转移到地质储层，从而促进碳的固存。在这项研究中，我们评估了北海北部弗拉登地泥质沉积中心有机碳的数量、质量和积累速率，这是一个低活跃沉积物堆积的地区，历史上和现在都有海底拖网捕捞。本研究分析的所有沉积物岩心均显示地表沉积物向上粗化，与泥沙扰动和筛分相一致。弗拉登南部的地面沉积物分选得特别好，总有机碳含量不足，碳酸钙含量丰富——这种模式与密集的拖网捕捞相一致。我们的研究结果表明，现代有机碳积累率非常低（~ 0.7 g C m−2 yr−1），有机质反应性很低（18.5%不稳定），现代拖网事件可能会干扰沉积物和过去~ 2300年积累的碳。这些结果表明，沉积物和有机碳积累速率是评估沉积碳脆弱性的重要考虑因素。
{"title":"Vulnerability of blue carbon stocks to disturbance in sediments with low burial efficiency","authors":"Z.A. Roseby , T. Sengupta , S.L. Ward , D.F. Vosper , M. Blaauw , C.M. Roberts , J.D. Scourse","doi":"10.1016/j.margeo.2025.107676","DOIUrl":"10.1016/j.margeo.2025.107676","url":null,"abstract":"<div><div>Continental shelf sediments – particularly soft, muddy habitats - serve as significant reservoirs of organic carbon over glacial-interglacial timescales and are subject to disturbance, notably from mobile bottom fishing gear. The quantity and quality of accumulated organic carbon varies across shelf environments, with muds storing more organic carbon than other substrate types. For effective marine management, it has been recommended that the reactivity, or ‘quality’, of organic matter should be considered when assessing the vulnerability of sedimentary carbon to disturbance. If management interventions are to be made to protect vulnerable organic carbon reservoirs on the seafloor, then it is also important to consider the burial efficiency of carbon. In areas of rapid sediment accumulation, carbon will be moved from surface to geological reservoirs more quickly, thus facilitating carbon sequestration. In this study, we assess the quantity, quality, and accumulation rate of organic carbon in the muddy depocenter of the Fladen Ground, northern North Sea - an area of low active sediment accumulation, with both historic and ongoing bottom trawling. All sediment cores analysed in this study display upwards coarsening of surface sediments, consistent with sediment disturbance and winnowing. Southern Fladen Ground sediments are especially well sorted, depleted in total organic carbon, and enriched in calcium carbonate - patterns that align with intensified trawling. Our results show very low modern organic carbon accumulation rates (∼0.7 g C m<sup>−2</sup> yr<sup>−1</sup>), low organic matter reactivity (18.5 % labile), and that modern trawl events can potentially disturb sediments and carbon accumulated over the last ∼2300 years. These results indicate that sediment and organic carbon accumulation rates are an important consideration when assessing the vulnerability of sedimentary carbon.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"492 ","pages":"Article 107676"},"PeriodicalIF":2.2,"publicationDate":"2025-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145692428","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-28DOI: 10.1016/j.margeo.2025.107675
Jaia Syvitski , Ross Powell , Kumiko Azetsu-Scott , Ken Asprey , Eric Hutton , Gywn Lintern
Flocculation dynamics of inorganic mineral grains are quantified for ten mid-to-high latitude, deep coastal basins along the Atlantic, Pacific and Southern Oceans. Suspended floc populations are imaged in situ, capturing an undisturbed water column. The basins receive and accumulate low carbon sediment via delivery of inorganic mineral flocs that carry a reactive organic carbon component during transport. Suspended particles are distributed among four particle reservoirs each characterized by a settling velocity (w) and floc size (D): 1) microflocs and constituent grains (D < 50 μm, w < 4 m/day); 2) medium size flocs (D = 50 to 650 μm, w = 4 to 32 m/day; 3) large flocs (D = 650–5000 μm, w = 32 to 172 m/day); and 4) strings of flocs (5–100 mm in length, w = 200 to 400 m/day) sometimes forming “fabrics”. Stratified currents control flocculation by providing the necessary conditions to support bio-mediated inorganic flocculation. A multi-layer classification scheme based on vertical trends in floc concentration and diameter is used to identify hotspots of flocculation growth and decay within a suite of particle layers: 1) surface layers, 2) flocculation fronts, 3) dilution layers, 4) steady-state layers, 5) deep basin waters, 6) bottom boundary layers, and 7) shelf nepheloid layers. Flocculation fronts form along oceanographic sill depths carrying shear turbulence, and similarly along brackish to seawater mixing depths. Once flocs enter deep basin waters, their properties change little during sedimentation. Transit time for flocs to reach a basin's seafloor ranged from 1 to 14 days for basin depths 73 to 873 m. Evidence suggests multiple aggregation processes (e.g. doubling, onion skin, chaos) can act simultaneously within basin waters. Insights from this study can inform environmental management, such as mitigating the effects of sedimentation from human activities and understanding the implications of climate change on fjord ecosystems.
{"title":"Inorganic mineral flocculation within mid-to-high latitude deep coastal basins","authors":"Jaia Syvitski , Ross Powell , Kumiko Azetsu-Scott , Ken Asprey , Eric Hutton , Gywn Lintern","doi":"10.1016/j.margeo.2025.107675","DOIUrl":"10.1016/j.margeo.2025.107675","url":null,"abstract":"<div><div>Flocculation dynamics of inorganic mineral grains are quantified for ten mid-to-high latitude, deep coastal basins along the Atlantic, Pacific and Southern Oceans. Suspended floc populations are imaged in situ, capturing an undisturbed water column. The basins receive and accumulate low carbon sediment via delivery of inorganic mineral flocs that carry a reactive organic carbon component during transport. Suspended particles are distributed among four particle reservoirs each characterized by a settling velocity (w) and floc size (D): 1) microflocs and constituent grains (D < 50 μm, w < 4 m/day); 2) medium size flocs (D = 50 to 650 μm, w = 4 to 32 m/day; 3) large flocs (D = 650–5000 μm, w = 32 to 172 m/day); and 4) strings of flocs (5–100 mm in length, w = 200 to 400 m/day) sometimes forming “fabrics”. Stratified currents control flocculation by providing the necessary conditions to support bio-mediated inorganic flocculation. A multi-layer classification scheme based on vertical trends in floc concentration and diameter is used to identify hotspots of flocculation growth and decay within a suite of particle layers: 1) surface layers, 2) flocculation fronts, 3) dilution layers, 4) steady-state layers, 5) deep basin waters, 6) bottom boundary layers, and 7) shelf nepheloid layers. Flocculation fronts form along oceanographic sill depths carrying shear turbulence, and similarly along brackish to seawater mixing depths. Once flocs enter deep basin waters, their properties change little during sedimentation. Transit time for flocs to reach a basin's seafloor ranged from 1 to 14 days for basin depths 73 to 873 m. Evidence suggests multiple aggregation processes (e.g. doubling, onion skin, chaos) can act simultaneously within basin waters. Insights from this study can inform environmental management, such as mitigating the effects of sedimentation from human activities and understanding the implications of climate change on fjord ecosystems.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"491 ","pages":"Article 107675"},"PeriodicalIF":2.2,"publicationDate":"2025-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145474755","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-27DOI: 10.1016/j.margeo.2025.107674
Zijian Xiao , Xiaoxia Huang , Katharina Hochmuth
This study used backstripping analysis, combined with a multi-proxy dataset comprising borehole logs, multi-channel seismic surveys, high-resolution bathymetric data, and regional tectonic constraints to quantitatively reconstruct the paleobathymetric evolution of Prydz Bay. As the third largest bay in Antarctica, Prydz Bay is located in front of the Lambert Glacier-Amery Ice Shelf of the East Antarctic continental margin. Prydz Bay is covered by rich multi-channel seismic lines, and Ocean Drilling Program Leg 119 and 188 provided available lithology data of 8 boreholes, establishing it as an ideal area for basin analyses and paleobathymetric evolution. Core porosity data indicated that the sedimentary strata on the continental shelf are overcompacted due to grounded glacier loading, while the slope exhibits hemipelagic sedimentary characteristics. Considering the variability of deposition history and different crustal structure, the compaction was calculated separately between the continental shelf and slope. By comparison with previous studies, our new results quantitatively infer the thickness of sediment variations, and more detailed paleobathymetric grids were produced in different stages since Eocene-Oligocene boundary. The newly reconstructed paleobathymetry contributes to the understanding of the depositional response of ice sheet dynamics and ocean circulation changes, providing critical constraints on the coupled glacial-ocean-sediment system. Furthermore, spatially explicit gridded data could be used to establish more realistic regional ice sheet, ocean circulation, and climate models in the future.
本研究采用反采分析方法，结合钻孔测井、多通道地震调查、高分辨率测深数据和区域构造约束等多代理数据，定量重建了Prydz湾的古测深演化。普莱兹湾是南极洲第三大海湾，位于南极洲东部大陆边缘的兰伯特冰川-阿莫里冰架前。Prydz Bay被丰富的多通道地震线覆盖，Ocean Drilling Program Leg 119和Leg 188提供了8个钻孔的可用岩性数据，使其成为盆地分析和古测深演化的理想区域。岩心孔隙度数据表明，陆架上沉积地层受地面冰川负荷作用过度压实，坡面呈现半深海沉积特征。考虑到沉积历史的可变性和地壳结构的差异性，陆架和陆坡之间的压实度分别计算。通过与前人研究结果的比较，定量地推断了沉积物厚度的变化，并建立了始新世-渐新世界线以来不同阶段的更详细的古水深网格。新重建的古水深测量有助于了解冰盖动力学和海洋环流变化的沉积响应，为冰川-海洋-沉积物耦合系统提供关键约束。此外，空间明确的网格数据可用于未来建立更真实的区域冰盖、海洋环流和气候模式。
{"title":"Paleo-bathymetric Evolution of Prydz Bay since the Eocene-Oligocene Boundary, East Antarctica","authors":"Zijian Xiao , Xiaoxia Huang , Katharina Hochmuth","doi":"10.1016/j.margeo.2025.107674","DOIUrl":"10.1016/j.margeo.2025.107674","url":null,"abstract":"<div><div>This study used backstripping analysis, combined with a multi-proxy dataset comprising borehole logs, multi-channel seismic surveys, high-resolution bathymetric data, and regional tectonic constraints to quantitatively reconstruct the paleobathymetric evolution of Prydz Bay. As the third largest bay in Antarctica, Prydz Bay is located in front of the Lambert Glacier-Amery Ice Shelf of the East Antarctic continental margin. Prydz Bay is covered by rich multi-channel seismic lines, and Ocean Drilling Program Leg 119 and 188 provided available lithology data of 8 boreholes, establishing it as an ideal area for basin analyses and paleobathymetric evolution. Core porosity data indicated that the sedimentary strata on the continental shelf are overcompacted due to grounded glacier loading, while the slope exhibits hemipelagic sedimentary characteristics. Considering the variability of deposition history and different crustal structure, the compaction was calculated separately between the continental shelf and slope. By comparison with previous studies, our new results quantitatively infer the thickness of sediment variations, and more detailed paleobathymetric grids were produced in different stages since Eocene-Oligocene boundary. The newly reconstructed paleobathymetry contributes to the understanding of the depositional response of ice sheet dynamics and ocean circulation changes, providing critical constraints on the coupled glacial-ocean-sediment system. Furthermore, spatially explicit gridded data could be used to establish more realistic regional ice sheet, ocean circulation, and climate models in the future.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"491 ","pages":"Article 107674"},"PeriodicalIF":2.2,"publicationDate":"2025-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145425339","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-26DOI: 10.1016/j.margeo.2025.107673
Dhishna Buljore , Stéphan J. Jorry , Gwenael Jouet , Patrick Bachèlery , Fabien Paquet
This study examines the Late Quaternary sedimentary and volcanic history of Zélée and Geyser Seamounts, carbonate platforms in the Mozambique Channel (south-west Indian Ocean). These seamounts are in a region influenced by active tectonics, glacial-interglacial sea-level cycles, and persistent volcanic activity from both local (Mayotte and Comoros Archipelago) and regional (Madagascar) sources. As a result, they display complex sedimentary and geomorphic characteristics. The research uses sediment cores and seismic profiles to identify four glacial-interglacial stages. It traces shifts in sediment provenance and documents a transition from Madagascar-derived siliciclastic inputs to volcanic sediments associated with Mayotte volcanism around 150 ka.
The analysis also tests a model of platform formation in general on two independently formed edifices, Zélée and Geyser. Detailed geomorphological mapping reveals steep slopes, terraces, volcanic cones, and erosional features. Seismic profiles show stratified deposits including turbidites of different origins. These turbidites highlight episodic sediment transport. Volcanoclastic layers are linked to volcanic events, while siliciclastic layers trace back to Madagascar. Calciturbidites reflect carbonate shedding from Zélée and Geyser during sea-level changes.
The findings enhance our understanding of carbonate platform evolution in tectonically active marine environments, emphasizing the influence of volcanism, tectonics, and climatic fluctuations on sediment distribution and platform morphology. This study contributes a refined perspective on sedimentary processes and sediment provenance in carbonate platforms, with broader implications for reconstructing past oceanographic conditions in similar regions.
{"title":"Geyser and Zélée seamounts and adjacent basin as witnesses of SW Indian Ocean tectonic and carbonate-siliciclastic-volcanoclastic sediment interplay","authors":"Dhishna Buljore , Stéphan J. Jorry , Gwenael Jouet , Patrick Bachèlery , Fabien Paquet","doi":"10.1016/j.margeo.2025.107673","DOIUrl":"10.1016/j.margeo.2025.107673","url":null,"abstract":"<div><div>This study examines the Late Quaternary sedimentary and volcanic history of Zélée and Geyser Seamounts, carbonate platforms in the Mozambique Channel (south-west Indian Ocean). These seamounts are in a region influenced by active tectonics, glacial-interglacial sea-level cycles, and persistent volcanic activity from both local (Mayotte and Comoros Archipelago) and regional (Madagascar) sources. As a result, they display complex sedimentary and geomorphic characteristics. The research uses sediment cores and seismic profiles to identify four glacial-interglacial stages. It traces shifts in sediment provenance and documents a transition from Madagascar-derived siliciclastic inputs to volcanic sediments associated with Mayotte volcanism around 150 ka.</div><div>The analysis also tests a model of platform formation in general on two independently formed edifices, Zélée and Geyser. Detailed geomorphological mapping reveals steep slopes, terraces, volcanic cones, and erosional features. Seismic profiles show stratified deposits including turbidites of different origins. These turbidites highlight episodic sediment transport. Volcanoclastic layers are linked to volcanic events, while siliciclastic layers trace back to Madagascar. Calciturbidites reflect carbonate shedding from Zélée and Geyser during sea-level changes.</div><div>The findings enhance our understanding of carbonate platform evolution in tectonically active marine environments, emphasizing the influence of volcanism, tectonics, and climatic fluctuations on sediment distribution and platform morphology. This study contributes a refined perspective on sedimentary processes and sediment provenance in carbonate platforms, with broader implications for reconstructing past oceanographic conditions in similar regions.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"491 ","pages":"Article 107673"},"PeriodicalIF":2.2,"publicationDate":"2025-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145425340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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