Marine Geology最新文献

{"title":"Mesophotic encrusting biotas and bioclastic deposits on the Western South Atlantic Equatorial margin: Geomorphological insights from the Amazon and Semi-Arid Coast Systems","authors":"João Regis dos Santos Filho ,&nbsp;João Victor Moraes da Costa Anjos ,&nbsp;Cleverson Guizan Silva ,&nbsp;Allan Kardec Duailibe Barros Filho ,&nbsp;Gilberto Tavares de Macedo Dias ,&nbsp;Alberto Garcia Figueiredo Jr. ,&nbsp;Amanda Bourguignon Cecilio ,&nbsp;Juliane Castro Carneiro","doi":"10.1016/j.margeo.2025.107544","DOIUrl":"10.1016/j.margeo.2025.107544","url":null,"abstract":"<div><div>Encrusting mesophotic biotas shaped by interactions between organisms, sedimentary processes, and environmental factors contribute significantly to bioclastic sediment compositions. This paper focuses on their distribution and relationship to deposits on the Western South Atlantic Equatorial Margin, particularly the Amazon and the Semi-Arid Coast. A comprehensive analysis of historical geological data and innovative mapping techniques, including GIS and seismic attribute integration, provides an understanding of its geomorphology and the extension of these benthic environments, that occupy an area of 29,830 km². A four-stage model explains the origin and development of these important deposits. Stage 1 reflects the initial formation of beachrocks, the erosion of sandstone outcrops, and the formation of rhodolith mounds during the Last Glacial Maximum. Stage 2, during the early Marine Transgression, is characterized by colonization of rocky surfaces. Stage 3 is marked by drowning and the transition from altiphotic to mesophotic environments. Stage 4 involves fully formed mesophotic encrusting biotas and associated bioclastic deposits, influenced by environmental conditions, including discharge of the Amazon River Plume. Enhanced regional seabed mapping aims to support marine management policies, promote sustainable resource use, and serve as a model for conservation efforts elsewhere.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"484 ","pages":"Article 107544"},"PeriodicalIF":2.6,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143685160","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":"Distinct sandbar behavior on a gently sloping shoreface sea-breeze dominated beach","authors":"Gabriela Medellín ,&nbsp;Alec Torres-Freyermuth ,&nbsp;Nicholas Cohn","doi":"10.1016/j.margeo.2025.107543","DOIUrl":"10.1016/j.margeo.2025.107543","url":null,"abstract":"<div><div>Sandbars are common features in sandy nearshore environments that readily migrate in response to changing hydrodynamic conditions and, when in shallow water, can provide coastal protection by inducing wave breaking and through sediment feeding to the beach. Prior process-based studies related the off- (on-) shore sandbar migration with the increase of the undertow current (wave acceleration skewness) associated to storm (mild) conditions. However, onshore sandbar migration has, under some circumstances, also been reported to occur during storms at mild sloping shorefaces. A comprehensive 9-year data set of (200) weekly to bi-weekly surveys of the beach and shallow nearshore, undertaken on an accretive micro-tidal sea-breeze dominated beach along the southeastern coast of Mexico, are presented here that shed new insights into hydrodynamic drivers of inner surf zone sandbar and shoreline dynamics. During spring-summer, short period waves, mainly associated to local sea-breezes, drive offshore sandbar migration. On the other hand, winter storms, occurring during fall-winter months, generate more energetic swell waves that induce onshore sandbar migration. In general, seasonal changes of shoreline and inner sandbar position are coupled, with on- (off-) shore sandbar migration being synchronous to seasonal shoreline advance (retreat), suggesting a gradual feeding of sediment from the bar system onto the beach. Analysis of the data, in conjunction with comparison to equilibrium model results, are used to explore the physical drivers of sub-seasonal sandbar evolution at the site. The sandbar dynamics in the study area, showing an opposite behavior to conventional expectation of storm-induced offshore transport, are well correlated to seasonal changes of waves properties. This distinct sandbar behavior might be present at other gently sloping shoreface sea-breeze dominated sandy beaches.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"484 ","pages":"Article 107543"},"PeriodicalIF":2.6,"publicationDate":"2025-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143685161","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mg/Ca heterogeneity in the benthic foraminifera Cibicidoides wuellerstorfi and Uvigerina peregrina","authors":"Trenity Ford,&nbsp;Ashley M. Burkett","doi":"10.1016/j.margeo.2025.107534","DOIUrl":"10.1016/j.margeo.2025.107534","url":null,"abstract":"<div><div>Laser ablation derived Mg/Ca ratios in the epibenthic foraminifera <em>Cibicidoides wuellerstorfi</em> and infaunal <em>Uvigerina peregrina</em> were analyzed from diverse Pacific Ocean sites, covering depths from 600 to 1800 m and bottom water temperatures (BWT) of 2–9 °C. Using Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS), multiple measurements were performed across specimen chambers to assess Mg/Ca variability. For <em>C. wuellerstorfi</em>, intra-chamber Mg/Ca ratios showed an average standard deviation of 0.319 mmol/mol with a mean of 1.41 mmol/mol (relative standard deviation, RSD, of 23.2 %), while inter-chamber variability reached 39.2 %. <em>U. peregrina</em> exhibited slightly lower variability, with a standard deviation of 0.184 mmol/mol and a mean ratio of 1.03 mmol/mol (RSD of 17.0 %). No consistent relationship was observed between Mg/Ca ratios and BWT for either species when using published temperature calibration eqs. A calibration considering carbonate ion concentration (Δ[CO₃²⁻]) improved the fit for <em>C. wuellerstorfi</em> samples at temperatures below 3 °C, suggesting Δ[CO₃²⁻] influences Mg incorporation in epifaunal foraminifera in colder waters. Further analysis of intertest Mg/Ca ratios across 23 specimens of <em>Cibicidoides wuellerstorfi</em> and 40 of <em>Uvigerina peregrina</em> revealed a lack of correlation with temperature, with R² values of 0.004 and 0.003, respectively. The lack of a temperature correlation with Mg/Ca values supports the hypothesis that factors beyond ambient temperature, such as biomineralization processes and carbonate ion concentration, affect Mg/Ca incorporation in the studied species. These results highlight the complexities in interpreting Mg/Ca ratios for these species as temperature proxies and suggest the need for further research to account for geochemical variability in these proxies, especially in LA-ICP-MS based datasets.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"484 ","pages":"Article 107534"},"PeriodicalIF":2.6,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143620896","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":"Modern bioturbation structures and their mixing effects in the Yangtze River Estuary and its adjacent sea areas","authors":"Xin Zhang ,&nbsp;Dejiang Fan ,&nbsp;Baoduo Wang ,&nbsp;Peng Cheng ,&nbsp;Judong Mao ,&nbsp;Xiaolin Ren ,&nbsp;Xueshi Sun","doi":"10.1016/j.margeo.2025.107533","DOIUrl":"10.1016/j.margeo.2025.107533","url":null,"abstract":"<div><div>Bioturbation structures are not only critical indicators to the state of the seafloor environment but also serve as important proxies for reconstructing paleo-environments. Furthermore, bioturbation processes will cause the redistribution of materials and early diagenesis in sediments, which makes it a challenging component to explore elements cycles or interpret sedimentary records over centennial time scale. This study, based on sediment cores from 31 stations in the Yangtze River Estuary and its adjacent areas, utilized high-resolution X-ray computed tomography (CT) scanning technology and MATLAB data processing method, along with measurements of sediment grain size and ²¹⁰Pb activity, to qualitatively and quantitatively characterize the bioturbation structures in the area and estimate mixing intensity. The results indicate that bioturbation structures can be functionally categorized into four types: biodiffusor structure, conveyors structure, regenerator structure and gallery-diffusor structure, with conveyors structure and gallery-diffusor structure being the most common. The vertical distribution patterns of bioturbation structures within the cores exhibit variations, including exponential decay pattern, fluctuating decay pattern, pulse distribution pattern, and uniform distribution pattern. Based on bioturbation intensity and their combinations, three bioturbation structural zones were identified: the Yangtze River Estuary bioturbation zone, the coastal sand ridge and northern Zhejiang-Fujian bioturbation zone, and the transitional phase and northern Zhejiang-Fujian muddy bioturbation zone. The mixing coefficients in this area ranges from 0.02 to 884.24 cm²/yr, exhibiting significant spatial variation. Strong mixing is observed in the pro-delta and delta front-shelf transition zones, while weaker mixing occurs in the northern Zhejiang-Fujian muddy area and the southern coastal region of northern Jiangsu coastal. The mixing effects are influenced not only by bioturbation but also by non-biological factors such as physical mixing.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"484 ","pages":"Article 107533"},"PeriodicalIF":2.6,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143592044","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":"Seafloor morphology and recent dynamics in the Scoglio d'Affrica (Northern Tyrrhenian Sea)","authors":"Anna Saroni ,&nbsp;Federica Maurantonio ,&nbsp;Daniele Casalbore ,&nbsp;Francesco L. Chiocci ,&nbsp;Ettore Cimenti ,&nbsp;Massimo Coltorti ,&nbsp;Maurizio Demarte ,&nbsp;Martina Pierdomenico ,&nbsp;Daniele Spatola ,&nbsp;Roberta Ivaldi","doi":"10.1016/j.margeo.2025.107518","DOIUrl":"10.1016/j.margeo.2025.107518","url":null,"abstract":"<div><div>From 2017 to 2023, the offshore area nearby the Scoglio d'Affrica islet, located in the Northern Tyrrhenian Sea, has been surveyed and monitored after a violent fluid emission from a shallow-water mud volcano that caused an outburst rising 10 m above the sea surface. This transient phenomenon occurred very localized and short-lived. Assessing the complexity of this kind of event requires an integrated monitoring system, which allows us to characterize the seafloor morphology and recent dynamics through high resolution swath bathymetry and direct visual seafloor observation. These data allow also the identification of new features produced by recent seafloor dynamics and fluid seepage related to mud volcanism, obtaining insights on the temporal and spatial evolution of the seafloor morphology related to cold seeps in the area. In particular, the mud volcano responsible for the 2017 gas outburst is made up of two shallow water mounds characterized by different seafloor evolutionary records, including sediment consolidation, fracturing and variation in morphology and height, likely related to inflation/deflation processes as well as to the sediment reworking by wave action.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"484 ","pages":"Article 107518"},"PeriodicalIF":2.6,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143620377","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":"Discoveries on coastal retrogressive breach failures inspired by failure of an underwater fixed platform","authors":"Xiamei Man ,&nbsp;William R. Dally ,&nbsp;David P. Callaghan ,&nbsp;Peter Nielsen","doi":"10.1016/j.margeo.2025.107530","DOIUrl":"10.1016/j.margeo.2025.107530","url":null,"abstract":"<div><div>Retrogressive breach failures (RBF) are submarine landslides that result in a nearly vertical sand wall above and below the water surface. Previous studies suggest a four-phase mechanism of RBFs, including triggering, propagation, termination, and recovery phases. There have been both laboratory and field studies on the later three phases, while the triggering mechanism of RBFs remain unknown given the event occurrence is unpredictable both spatially and temporally.</div><div>Amity Point on North Stradbroke Island, 37 km Northeast from Brisbane, Australia is a valuable coastal flow slide study site with frequent occurrence of approximately every two weeks (<span><span>Beinssen et al., 2014</span></span>) of them at a fixed location. Aiming at revealing the triggering mechanism of flow slides, an eight-meter-tall underwater tripod was manufactured and anchored on the seabed. The tripod location was designed to be fixed at a point with minimum bathymetry change during flow slide events referring to existing studies (<span><span>Beinssen et al., 2014</span></span>) with between 1.5 m and 2 m deep helical anchors. The tripod collapsed overnight by the undermining of two of the three helical anchors, including the 2 m deep anchor, by a significant underwater flow slide while there was minimal flow slide evidence on the beach.</div><div>The short lifespan of the tripod presents the complexity of RBFs (especially underwater) and the limitations of existing research. Underwater RBF events that do not propagate to the shore (or slightly erode the shore) occur more frequently than previous research reported (<span><span>Beinssen et al., 2014</span></span>). While it does not propagate to the shore, the event still erodes a significant amount of sand underwater. It indicates the triggering occurs at 10 m underwater or even deeper.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"484 ","pages":"Article 107530"},"PeriodicalIF":2.6,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143592045","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The tsunami history and prehistory of Nuʻu Refuge, Maui, Hawaiʻi","authors":"Scott Fisher ,&nbsp;James Goff ,&nbsp;Andrew B. Cundy ,&nbsp;David Sear","doi":"10.1016/j.margeo.2025.107522","DOIUrl":"10.1016/j.margeo.2025.107522","url":null,"abstract":"<div><div>In the 21st century tsunamis have claimed the lives of at least 253,000 people globally, making them one of the deadliest natural disasters. In Hawai'i, destructive events occur, on average, every 11 years. This study takes a multi-proxy approach to understand the magnitude and frequency of tsunamis at the Nuʻu Refuge, Kaupō, Maui, Hawai'i. Research there revealed sedimentary evidence of four tsunami or storm events dating from as early as 1837 CE from both local and distant sources. Sedimentary evidence from the wetlands indicates a depositional environment dominated by tsunami inundation coupled with increasing isolation from the sea. Understanding (a) the source, magnitude and frequency of tsunami events and (b) ongoing geomorphological change provides a foundation for developing mitigation strategies to reduce the destructive potential of future tsunamis.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"483 ","pages":"Article 107522"},"PeriodicalIF":2.6,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143534796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Drilling the New Jersey shallow shelf to evaluate Miocene continental margin sequences, sea level, and resources","authors":"K.G. Miller ,&nbsp;G.S. Mountain ,&nbsp;J.N. Proust ,&nbsp;A. Mukhatzhanov ,&nbsp;J.V. Browning ,&nbsp;W.J. Schmelz ,&nbsp;S.P. Hesselbo ,&nbsp;D.M. Hodgson ,&nbsp;M.E. Katz ,&nbsp;J. Lofi ,&nbsp;P.J. Sugarman ,&nbsp;D. Monteverde","doi":"10.1016/j.margeo.2025.107521","DOIUrl":"10.1016/j.margeo.2025.107521","url":null,"abstract":"<div><div>We review scientific ocean drilling of the New Jersey passive continental margin and the success of Integrated Ocean Drilling Program (IODP¹) Expedition 313 in addressing long-standing, fundamental issues of sequence stratigraphy, sea-level change, and resources. The New Jersey margin was targeted for study by several generations of ocean drilling because of its thick, prograding Oligocene to Quaternary sequences bounded by unconformities. Coring and logging on the onshore coastal plain (Ocean Drilling Program [ODP] Legs 150X<span><span>http://www-odp.tamu.edu/publications/citations/cite150X.html</span><svg><path></path></svg></span> and 174AX), outer continental shelf (Leg 174A), and continental slope and rise (Legs 95, 150, and 174A) provided a chronology of sea-level lowerings but did not sample facies needed to evaluate Miocene sea-level amplitudes. Expedition 313 used a Mission Specific Platform (L/B <em>Kayd</em>) to drill on the shallow continental shelf, recover critical Miocene facies, particularly on clinoform foresets, and capture the full amplitudes of relative sea-level changes. Expedition 313 overcame challenging borehole conditions and recovered a total of 1311 m of core at three sites (81 % recovery) that:<ul><li><span>(1)</span><span><div>correlated difficult-to-date nearshore-shelf facies to the time scale with resolution better than ±0.5 million years (Myr);</div></span></li><li><span>(2)</span><span><div>tested and confirmed that sequence boundaries are a primary cause of seismic reflections on siliciclastic shelves;</div></span></li><li><span>(3)</span><span><div>tested sequence stratigraphic models with core-log-seismic integration; and.</div></span></li><li><span>(4)</span><span><div>provided a record of paleodepth changes through time that constrained amplitudes of Miocene sea-level change, including the influence of mantle dynamic topography. The New Jersey relative sea-level estimates are similar to those obtained using stable isotopes and Mg/Ca paleothermometry, showing that GMGSL (“eustasy”) varied with 10–60 m scale amplitudes on the Myr scale.</div></span></li></ul></div><div>Drilling beneath the shallow continental shelf also identified groundwater sources, including seawater, deep-sourced brines, and meteoric fresh water, that represent potential resources for future generations. Studies of this margin have implications for future subsurface storage of supercritical CO₂ and geotechnical issues relating to the location of offshore wind infrastructure. Expedition 313 demonstrated the feasibility of continuously recovering and logging strata in shallow water, providing constraints on sea level, sequences, hydrogeology, and resources.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"484 ","pages":"Article 107521"},"PeriodicalIF":2.6,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143550556","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Decadal shifts and future projections of the Han River Delta coastline","authors":"Xiu Juan Liu ,&nbsp;Jie Ni Xü ,&nbsp;Albert J. Kettner ,&nbsp;Yang Wang ,&nbsp;Jia Ji Yi","doi":"10.1016/j.margeo.2025.107520","DOIUrl":"10.1016/j.margeo.2025.107520","url":null,"abstract":"<div><div>The Han River Delta, the sixth largest delta in China, has received decreasing amounts of fluvial sediments over the last decades. Here, we use satellite images for 1981–2020 and a conceptual geometric model to investigate recent and future evolution of the delta coastline. Satellite images were able to capture the transition from a more natural coastline with sandy beaches to an artificial structure since 2015. This transition has been accompanied by rapid seaward migration of a portion of the artificial coastline due to land reclamation. Furthermore, most of the coastline has remained stable (showing no significant advance or retreat), except for coastlines that are dominated by mangrove forest. The coastline has not always remained stable. Before the 1980s, the coastline was continuously advancing. Modeling results reveal that a significant reduction of fluvial sediment, mainly caused by upstream dam emplacement, had a key role in the shifting status of the delta coastline evolution. Additionally, model results suggest that if fluvial sediment supply had remained consistent with pre-dam levels, the more abundant fluvial sediment supply could counteract the effects of a maximum sea-level rise scenario for decades. However, a sustained decrease of the fluvial sediment supply, at rates similar to the less abundant sediment supply at present, is expected to dominate the evolution of the delta coastline under a conservative sea level rise scenario. In the case of a medium or maximum sea level rise scenario, the future evolution of the delta coastline will be dominated by the rate at which sea level rises, rather than a further decrease of riverine sediment. The large-scale land reclamation has a negligible impact on the advance or retreat rate of the delta coastline. These findings offer valuable insights for the management of delta coastlines.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"484 ","pages":"Article 107520"},"PeriodicalIF":2.6,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143550557","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":"Tracking diagenetic alteration of magnetic susceptibility in thrust ridge and slope basin sediments of the Cascadia margin (ODP Sites 1249 and 1252; IODP Site U1325)","authors":"Stephen C. Phillips ,&nbsp;Joel E. Johnson ,&nbsp;William C. Clyde ,&nbsp;Wei-Li Hong ,&nbsp;Jacob B. Setera ,&nbsp;Marta E. Torres","doi":"10.1016/j.margeo.2025.107519","DOIUrl":"10.1016/j.margeo.2025.107519","url":null,"abstract":"&lt;div&gt;&lt;div&gt;We investigated sediment core records from the Cascadia Margin (Ocean Drilling Program Sites 1249 and 1252 at Hydrate Ridge; Integrated Ocean Drilling Program Site U1325 offshore Vancouver Island) using a Zr/Rb heavy mineral proxy from X-ray fluorescence (XRF) core scanning to identify intervals of primary detrital magnetic susceptibility (κ) and predict intervals where diagenesis caused magnetite dissolution by hydrogen sulfide. We also measured total sulfur (TS) content, grain size distributions, total organic carbon (TOC) content, and the magnetic mineral assemblage to further constrain the role of diagenesis on κ. Understanding how κ can be used to better characterize the varied effects of detrital and diagenetic signals in marine settings is important for understanding biogeochemical cycling and records of paleoenvironmental change. The upper 100 m of slope basin Site 1252 contains multiple intervals (&gt; 90 m total) of decreased κ correlated with elevated TS content, consistent with dissolution of magnetite and precipitation of pyrite, iron monosulfides, and/or elemental sulfur. Similarly at the other slope basin site, Site U1325, κ is lower and TS is elevated in the interval between 24 and 51 mbsf, due to sulfide formation. At both slope basin sites, these low κ intervals correspond with high TOC, suggesting the possibility that organoclastic sulfate reduction (OSR) is likely a major driver of diagenetic alteration of κ at these sites. High TS:TOC ratios at Site U1325 suggests anaerobic oxidation of methane (AOM) during sulfate-methane transition zone (SMTZ) migration may have contributed to alteration of κ. In contrast, within the upper 90 m of Site 1249, a methane seep site at the summit of Hydrate Ridge, κ is almost entirely altered by diagenetic processes, with much of the low κ explained by a high degree of iron sulfide formation, while some intervals are affected by precipitation of magnetic iron sulfides that maintain or even increase κ. The presence of abundant methane seepage and gas hydrate as well as chemosynthetic seafloor fauna at this site, suggests that sulfide is released to the water column and AOM, rather than OSR, drives diagenetic alteration of κ at this site. Overall, the slope basin sites show episodic variation of κ that is influenced by TOC content, likely driven by changes in marine primary productivity and sedimentation rate, while the seep site shows consistently altered κ with lower TS content and no correlation with TOC. Methane seep environments likely experience loss of hydrogen sulfide to the water column and oxidation of hydrogen sulfide by seafloor seep fauna, which limits the amount of solid phase sulfur (pyrite, iron monosulfides, elemental sulfur) that can be precipitated within the sediments. In contrast, the migration of a buried SMTZ at slope basin sites results in enhanced sulfur precipitation within the sediments. This integrated magnetic and geochemical approach reveals the diagenetic p","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"483 ","pages":"Article 107519"},"PeriodicalIF":2.6,"publicationDate":"2025-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143512207","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}