Marine Geology最新文献

{"title":"The incompleteness of turbidite records: Comparing direct monitoring of turbidity currents to deposits preserved in submarine fans (Pointe-des-Monts, eastern Canada)","authors":"Florian Jacques ,&nbsp;Alexandre Normandeau ,&nbsp;Jean-Carlos Montero-Serrano ,&nbsp;Guillaume St-Onge ,&nbsp;Audrey Limoges ,&nbsp;André Rochon ,&nbsp;Urs Neumeier ,&nbsp;Patrick Lajeunesse ,&nbsp;Daniel Bourgault","doi":"10.1016/j.margeo.2025.107660","DOIUrl":"10.1016/j.margeo.2025.107660","url":null,"abstract":"<div><div>The recurrence of turbidity currents in submarine canyons is often assessed using sediment core records from submarine fans, which are generally assumed to reflect canyon processes. However, this assumption has rarely been tested. Here, we assess the completeness of modern sedimentary records in the Pointe-des-Monts submarine fan, located in the Lower St. Lawrence Estuary, eastern Canada, by comparing turbidity current activity derived from repeat multibeam bathymetry, direct monitoring observations, and short sediment cores. The timelapse bathymetry and monitoring results revealed that turbidity current activity over the last 15 years was primarily driven by storms, especially during ice-free winters. Since 2007, a minimum of nine turbidity currents were recorded by timelapse multibeam bathymetry and direct observations in the canyon system, many of which have led to the migration of cyclic steps within the canyon axis. However, turbidites recorded in the short sediment cores on the lobe predate all monitoring efforts, indicating a largely incomplete record of canyon processes preserved on the seafloor. The absence of modern turbidites (≤15 years) in the submarine fan is interpreted to result from bottom current reworking, bioturbation, and the dilution of turbidity currents as they become unconfined on the submarine fan. This study highlights that bottom currents can extensively remobilize turbidites, resulting in a largely incomplete record of turbidity currents on submarine fans. Consequently, caution is needed when reconstructing their recurrence and sediment dynamics using sediment cores, particularly in such dynamic nearshore systems.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"491 ","pages":"Article 107660"},"PeriodicalIF":2.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145526045","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}

{"title":"Geyser and Zélée seamounts and adjacent basin as witnesses of SW Indian Ocean tectonic and carbonate-siliciclastic-volcanoclastic sediment interplay","authors":"Dhishna Buljore ,&nbsp;Stéphan J. Jorry ,&nbsp;Gwenael Jouet ,&nbsp;Patrick Bachèlery ,&nbsp;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":"2026-01-01","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}

{"title":"Post-glacial sandy contourite drifts in the Malta-Gozo Channel (Pelagian Platform, central Mediterranean Sea): Characteristics, bottom currents and implication for shallow-water contourite systems","authors":"Daniele Spatola ,&nbsp;Aaron Micallef ,&nbsp;Daniele Casalbore ,&nbsp;Francesco Latino Chiocci ,&nbsp;Eleonora Martorelli","doi":"10.1016/j.margeo.2025.107672","DOIUrl":"10.1016/j.margeo.2025.107672","url":null,"abstract":"<div><div>An increasing number of studies have documented the occurrence of sandy contourites in modern systems. However, knowledge on their characteristics and links with oceanographic processes remains limited. In particular, the pattern of bottom current circulation on the Pelagian Platform (central Mediterranean Sea) and its driving mechanisms are poorly understood. To address these gaps, we analyse newly acquired very high-resolution geophysical and sedimentological data from offshore the Maltese Islands, which allow us to identify small-scale, sandy contourite drifts (named EM1–5), located in shallow water (depths between 50 and ∼ 100 m). Using a dense grid of high-resolution seismic profiles, multibeam bathymetry, and sedimentological analyses, we detail the internal and external geometry, morphology, and sedimentology of the deposits. Drifts EM1a, EM1b, EM1c, EM2, EM3, and EM5 appear as small elongated mounded deposits (separated and plastered drifts) cropping on the shelf seafloor, while EM4 is a buried mounded deposit located in the southern part of the study area. The spatial distribution of the studied drifts suggests that their formation is driven by a mesoscale anticyclonic gyre, tentatively ascribed to the Malta-Sicily Gyre, with currents enhanced by topographic interactions. Stratigraphic evidence suggests that this oceanographic dynamic has played a significant role in shaping the Maltese insular shelf since at least the Holocene, highlighting the potential of the Pelagian Platform to form carbonate sandy contourites. These findings advance the understanding of shallow-water (shelf-channelized) contourite systems and offer valuable insights to refine sedimentation models for carbonate-rich contourite deposits in temperate settings.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"491 ","pages":"Article 107672"},"PeriodicalIF":2.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145364405","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}

{"title":"Multiple methane release events from Cascadia Margin sediments since 1 Ma inferred from pyrite multiproxy data","authors":"Qiang Song ,&nbsp;Jiasheng Wang ,&nbsp;Thomas J. Algeo ,&nbsp;Can Chen ,&nbsp;Zhou Wang ,&nbsp;Qin Yang ,&nbsp;Kunlong Geng ,&nbsp;Qing Li","doi":"10.1016/j.margeo.2025.107670","DOIUrl":"10.1016/j.margeo.2025.107670","url":null,"abstract":"<div><div>Large-scale methane release events (MREs), which can trigger transient climatic hyperwarming, are associated with enhanced anaerobic oxidation of methane (AOM), generating diagnostic geochemical and petrographic signatures in authigenic pyrite. Previous studies of MREs have analyzed single proxies such as pyrite framboid size or the sulfur isotopic composition of bulk-sediment pyrite over short core intervals, providing insufficient data regarding the intensity and magnitude of such events. Here, we utilize multiple proxies (i.e., pyrite framboid content, size, and sulfur isotopic composition) to reconstruct a detailed history of paleo-MREs at Site U1329 (IODP Leg 311) on the Cascadia Margin since 1 Ma. The recovered pyrite consists mainly (&gt;99%) of isolated framboids and framboid aggregates, some having late diagenetic overgrowths. The characteristics of these framboids reflect the intensity and magnitude of each MRE: strong events were associated with FeS₂ &gt; 1.0 wt.%, mean framboid size &gt;20 μm, and Δ³⁴S &lt; 0‰ (where Δ³⁴S = δ³⁴S_CRS – δ³⁴S_SMTZ), whereas weak events were associated with FeS₂ = ∼0.5-1.0 wt.%, mean framboid size ∼10-20 μm, and Δ³⁴S &gt; 0‰. The study core contains four MREs (one strong, three medium) with mean pyrite content of 1.27 wt.%, mean framboid diameter of 26±6 μm, and mean Δ³⁴S of 10.5‰ (cf. background interval values of 0.85 wt.% mean FeS₂ content; 12±2 μm mean framboid diameter; and 16.0‰ mean Δ³⁴S). Each MRE was associated with a glacio-eustatic lowstand, a relationship reflecting destabilization of gas hydrates through pressure release, leading to an upward flux of methane, shallowing of the sulfate-methane transition zone (SMTZ), and enhanced AOM activity. Our results indicate that the morphological and geochemical signatures of pyrite are important carriers of paleoclimate information that can be used to study the occurrence and intensity of paleo-methane events and further improve understanding of methane hydrate dynamics.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"491 ","pages":"Article 107670"},"PeriodicalIF":2.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145425276","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}

{"title":"Buried Middle Miocene cyclic steps on the northwestern slope of the Xisha carbonate platform, South China Sea","authors":"Biwen Wang ,&nbsp;Jinfeng Ren ,&nbsp;Zenggui Kuang ,&nbsp;Guangfa Zhong","doi":"10.1016/j.margeo.2025.107671","DOIUrl":"10.1016/j.margeo.2025.107671","url":null,"abstract":"<div><div>High-amplitude undulating seismic reflections within the Middle Miocene strata on the northwestern slope of the Xisha carbonate platform, located on the northwestern continental margin of the South China Sea, have drawn significant research interest over the past decade. Several conflicting genetic models have been proposed, including those suggesting carbonate reefs, turbidity-current or bottom-current channels, and fault-related features. This study examines the morphology, internal structures, and distribution of these undulations using 3D seismic data, combined with 2D seismic and drilling data. These undulations are characterized by long wavelength (0.5–2.3 km), low wave height (15–80 m), large aspect ratios (20–60), upslope-migrating waveforms, upslope-asymmetric cross-sectional morphology, typical stoss-side backset beddings and truncated lee sides, and are therefore identified as cyclic steps associated with supercritical flows. The slope-parallel crestlines of the cyclic steps further indicate their turbidity-current origin. Some coexisting downslope extending linear depressions are attributed to turbidity-current channels. Development of the cyclic steps is closely associated with the evolution of the Xisha carbonate platform. During the early Middle Miocene, when the carbonate platform productivity was high, abundant calcareous sediments were delivered from the platform margin to the study area, contributing to the formation of the cyclic steps in the lower slope off the platform. As the platform was drowning in the late Mid-Late Miocene, sediment supply from the platform was reduced, leading to the abandonment of the bedforms, with the bedform troughs being infilled by interbedded hemipelagites and turbidites. Our findings are significant for a better understanding of 3D morpho-sedimentary architecture of buried supercritical-flow bedforms that have been rarely reported, with implications for regional paleogeographic reconstructions and carbonate platform evolution.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"491 ","pages":"Article 107671"},"PeriodicalIF":2.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145364440","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}

{"title":"Paleo-bathymetric Evolution of Prydz Bay since the Eocene-Oligocene Boundary, East Antarctica","authors":"Zijian Xiao ,&nbsp;Xiaoxia Huang ,&nbsp;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":"2026-01-01","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}

{"title":"From impact to extinction to recovery: Discoveries of IODP-ICDP Expedition 364 to the Chicxulub impact structure","authors":"S.P.S. Gulick ,&nbsp;P. Kaskes ,&nbsp;C.M. Lowery ,&nbsp;A.S.P. Rae ,&nbsp;S.M. Tikoo","doi":"10.1016/j.margeo.2025.107661","DOIUrl":"10.1016/j.margeo.2025.107661","url":null,"abstract":"<div><div>In 2016, International Ocean Discovery Program Expedition 364, with support from the International Continental Scientific Drilling Program, drilled into the peak ring of the Chicxulub impact structure, famous for its causal link to the mass extinction at the end of the Cretaceous. In this summary paper, we discuss key findings from Site M0077 on the cratering processes, marine ecosystem recovery after the mass extinction, and the post-impact hydrothermal system and habitability of the impact structure. Important results include (1) the confirmation of the dynamic collapse model of peak ring formation, (2) insights into impactite emplacement processes on Earth, where water is a key component, (3) discovery of the iridium anomaly within the impact basin, unequivocally linking the Chicxulub impact basin to the global Cretaceous-Paleogene (K-Pg) boundary layer, (4) evidence for key atmospheric inputs of dust, sulfate aerosols, and soot, all likely contributing to global cooling and reduction of photosynthesis as drivers for extinction, (5) rapid recovery of life within the ocean overlying the crater, including a primary succession driven by in part by picoplankton before a transition over 100 s kyr to diversifying planktic communities, and (6) the presence of a long-lived hydrothermal system with extant thermophilic life in the buried peak ring 66 Myr later. The Chicxulub crater represents exceptional scientific opportunity in that it bridges planetary science, impact dynamics, and astrobiology; the integration of such findings continue to reveal the transformative power of asteroid impacts as a major geologic and biologic process.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"491 ","pages":"Article 107661"},"PeriodicalIF":2.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145334751","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}

{"title":"Impact of fluffy layer and bedform on turbulent intermittency in tidally induced bottom boundary layer","authors":"Zhixin Cao,&nbsp;Chao Li,&nbsp;Zhenkun Lin,&nbsp;Yaokun Lin,&nbsp;Zhaohui Deng,&nbsp;Jiaxue Wu,&nbsp;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":"2026-01-01","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}

{"title":"Deep-water canyon-channel systems of the Queensland Plateau, Northeast Australia","authors":"Sebastian Lindhorst ,&nbsp;Linus Budke ,&nbsp;Robin J. Beaman ,&nbsp;Jan Oliver Eisermann ,&nbsp;Christian Hübscher ,&nbsp;Niko Lahajnar ,&nbsp;Thomas Lüdmann ,&nbsp;Jody M. Webster ,&nbsp;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 &gt;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":"2026-01-01","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}

{"title":"Inorganic mineral flocculation within mid-to-high latitude deep coastal basins","authors":"Jaia Syvitski ,&nbsp;Ross Powell ,&nbsp;Kumiko Azetsu-Scott ,&nbsp;Ken Asprey ,&nbsp;Eric Hutton ,&nbsp;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 &lt; 50 μm, w &lt; 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":"2026-01-01","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}