Marine Geology最新文献

{"title":"Daily timescale analysis of sediment transport and topographic changes on a mesotidal sandy beach under low to moderate wave conditions","authors":"Isaac Rodríguez-Padilla ,&nbsp;Ismael Mariño-Tapia ,&nbsp;Amaia Ruiz de Alegría-Arzaburu","doi":"10.1016/j.margeo.2024.107323","DOIUrl":"https://doi.org/10.1016/j.margeo.2024.107323","url":null,"abstract":"<div><p>Understanding sediment transport processes on natural sandy beaches is essential for gaining insights into beach recovery and making effective coastal management decisions. This study examines surfzone sediment transport rates related to beachface morphological variations on an embayed mesotidal sandy beach located on the northwestern coast of the Baja California Peninsula in Mexico. Data were collected during a week-long field experiment conducted in June 2016 under low-to-moderate wave energy conditions (<span><math><msub><mi>H</mi><mi>s</mi></msub><mo>=</mo><mn>0.4</mn><mo>−</mo><mn>1.3</mn><mspace></mspace><mi>m</mi></math></span>). Daily topographical surveys and continuous measurements of near-bottom suspended sediment fluxes were conducted alongside the application of an extended energetics-based model that accounted for velocity and acceleration skewness. Results reveal contrasting accretionary and erosive patterns in the inner surfzone, along with consistent sediment deposition in the swash zone throughout the study period. Onshore sediment transport is found to be related to short-period calm wave conditions (<span><math><msub><mi>H</mi><mi>s</mi></msub><mo>&lt;</mo><mn>0.7</mn></math></span> m; <span><math><msub><mi>T</mi><mi>p</mi></msub><mo>&lt;</mo><mn>10</mn></math></span> s) and a weak undertow (&lt;0.2 ms⁻¹). Alongshore nonuniform wave breaking, influenced by irregular bathymetry and moderate-energetic oblique waves from the northwest, contributes to an alongshore gradient in sediment transport rate, leading to erosion in the northern part of the intertidal beach and accretion in the southern part. Suspended sediment flux measurements at 0.2 m above the bed suggest offshore mean transport predominates over oscillatory transport throughout the field experiment. Nevertheless, this observation should be interpreted with caution, as the flux is not vertically integrated across the water column and does not consider fluid acceleration. The model predictions effectively replicate sediment transport rates and consequent volumetric changes (Accuracy = 55–<span><math><mn>63</mn><mo>%</mo></math></span>; RMSE = 44–69 m³; <span><math><mtext>Bias</mtext><mo>=</mo><mo>−</mo><mn>2</mn></math></span> to −61 m³), although they underestimate observed accretion by a factor of three and overestimate erosion by a factor of two. Overall, this research highlights the complexities of natural sandy beach recovery processes in mesotidal environments and emphasizes the importance of considering both cross-shore and longshore components in sediment transport assessments.</p></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"474 ","pages":"Article 107323"},"PeriodicalIF":2.9,"publicationDate":"2024-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141244729","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":"High-resolution seismic record of the Quaternary palaeoenvironments along a Dalmatian-type coast (Lošinj Channel, Adriatic Sea)","authors":"Dea Brunović ,&nbsp;Ozren Hasan ,&nbsp;Slobodan Miko ,&nbsp;Nikos Georgiou ,&nbsp;Maria Geraga ,&nbsp;Dimitris Christodoulou ,&nbsp;Xenofon Dimas ,&nbsp;Nikolina Ilijanić ,&nbsp;George Papatheodorou","doi":"10.1016/j.margeo.2024.107325","DOIUrl":"https://doi.org/10.1016/j.margeo.2024.107325","url":null,"abstract":"<div><p>Coastal systems have changed considerably in response to Quaternary glacial–interglacial variability. Here, we offer the first detailed assessment of geomorphic features and late Quaternary sedimentation dynamics in the Lošinj Channel in the Adriatic Sea. The present study attempts to resolve the complex evolution of the environments by applying high-resolution seismic records that build upon sediment core data. Within this coastal karst basin, a significant amount of sediment accumulated during the Quaternary. Notably, the existence of several prominent erosional and depositional environments was revealed. We distinguished recurrent episodes of fluvio-lacustrine and marine sedimentation that probably occurred since Marine Isotope Stage (MIS) 6. The preserved record consists of erosional features and subparallel and oblique reflectors attributed to glacial periods (Seismic Units SU-II, SU-IV, and SU-V). Interglacial units are acoustically semitransparent and generally reflection-free (Seismic Units SU-I and SU-III). The mutual influence of sea level and climate change, sill depth, and karst hydrology enabled environmental changes in the Lošinj Channel. The area proves to be important for Quaternary studies because it contains a long sediment succession spanning at least the middle and late Pleistocene and Holocene. Our study has implications for the assessment of the long-term palaeoenvironmental evolution of similar coastal settings and reconstruction of the regional palaeogeography which is in turn crucial for understanding prehistoric human occupation and/or dispersal. This is one of the few well-preserved records in the Adriatic Sea that provides insight into submerged landscapes and sea levels since the penultimate glacial.</p></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"474 ","pages":"Article 107325"},"PeriodicalIF":2.9,"publicationDate":"2024-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141244772","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":"The application of carbonate and sediment budgets to assess the stability of marginal reef systems","authors":"Shannon Dee ,&nbsp;Adi Zweifler ,&nbsp;Michael Cuttler ,&nbsp;Jake Nilsen ,&nbsp;Joshua Bonesso ,&nbsp;Michael O'Leary ,&nbsp;Nicola K. Browne","doi":"10.1016/j.margeo.2024.107324","DOIUrl":"https://doi.org/10.1016/j.margeo.2024.107324","url":null,"abstract":"<div><p>Coral reefs and their associated landforms (carbonate islands and shorelines) are under increasing threat from the effects of anthropogenic climate change, including sea level rise (SLR). The ability of a reef to keep up with SLR depends on the rate of calcium carbonate accretion. Census-based carbonate budgets quantify rates of net calcium carbonate production on a reef and facilitate estimations of vertical reef accretion potential (RAP). To date, most carbonate budget studies have been undertaken in clear-water settings resulting in a limited understanding of how inshore reefs situated in more marginal environmental settings are functioning now and under future climate change. Here, we applied census-based carbonate framework across two inshore island reefs exposed to episodes of high turbidity within the Pilbara, Western Australia. Low net carbonate production (mean = 1.11 and 0.62 kg m⁻² yr⁻¹) was predominantly driven by low coral cover (&lt;10%) and low calcification rates. Importantly, bioerosion rates were also low (&lt;0.1 kg m⁻² yr⁻¹), maintaining positive carbonate budgetary states. Net sediment production rates were also low (mean = 0.06 kg m⁻² yr⁻¹) and were found to be mostly derived from coral, or mollusc material produced by invertivores. Calculated RAP estimates are below current and predicted rates of SLR, suggesting that these turbid reefs will soon struggle to keep up with increasing water depth and shoreline inundation.</p></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"473 ","pages":"Article 107324"},"PeriodicalIF":2.9,"publicationDate":"2024-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0025322724001087/pdfft?md5=6b7600dcbf7ba6008d02588b3c43b689&pid=1-s2.0-S0025322724001087-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141097470","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":"Unveiling coastal dynamics: Investigating beach sediment distribution patterns along the Lithuanian Baltic Sea coast through heavy mineral analysis","authors":"Dovilė Karlonienė ,&nbsp;Luca Caracciolo ,&nbsp;Donatas Pupienis","doi":"10.1016/j.margeo.2024.107320","DOIUrl":"10.1016/j.margeo.2024.107320","url":null,"abstract":"<div><p>Effective coastal management requires an understanding of sediment dynamics. This study examines the distribution of heavy minerals (HMs) in two distinct coastal regions: the mainland and spit, each with unique sediment deposition patterns. The spit accumulates sediment through alongshore sediment transport (AST), while the mainland experiences erosive processes and significant human impacts. The hydrodynamic behaviour and weathering resistance of HMs enables source identification. This has helped to reveal differences between the two regions, with apatite being characteristic of spit sediments and garnet of mainland beaches. Coastal processes, such as erosion, sediment transport, and accumulation, significantly shape the distribution of the HMs, with garnets dominating erosive shores and amphiboles dominating accumulative shores. Furthermore, the study found that human-made coastal infrastructure also affects the composition of HMs and the sediment distribution through AST. This research has implications beyond the local level, providing global insights into the complexities of coastal dynamics. The study emphasises the importance of using HM analysis in conjunction with grain size analysis to understand the distribution of beach sediment composition. It also highlights the significant role of coastal processes, including anthropogenic impacts such as jetty construction or deepening port entrance canals on AST.</p></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"474 ","pages":"Article 107320"},"PeriodicalIF":2.9,"publicationDate":"2024-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141136463","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":"TC activity affected the northern sea of the Shandong Peninsula over the past 1500 years and its driving mechanism","authors":"Wenzhe Lyu ,&nbsp;Tengfei Fu ,&nbsp;Zhen Cui ,&nbsp;Yancheng Wang ,&nbsp;Wenquan Liu ,&nbsp;Xingyong Xu ,&nbsp;Hongjun Yu","doi":"10.1016/j.margeo.2024.107311","DOIUrl":"10.1016/j.margeo.2024.107311","url":null,"abstract":"<div><p>Modern observational records indicate that the activity of tropical cyclone (TC) has been influenced by changes in tropical sea surface temperatures over the past century. However, due to a lack of direct observational records and the low resolution of current TC reconstructions, further investigation is needed to understand the driving factors behind TC activity. Additionally, key parameters such as TC paths and the extent of their impact remain unclear, with limited research on the characteristics of TC impacts in the northern sea of the Shandong Peninsula. In this study, we utilized sedimentary records from the muddy area to reconstruct the TC impact history in the northern sea of the Shandong Peninsula over the past 1500 years. Our reconstruction results indicate that TC activity affected the north China Sea region during the intervals 1000–1600 CE and 1850–2000 CE, TC activity showed an increasing and decreasing trend before and after 1300 CE, respectively. Research suggests that on a centennial scale, TCs affecting the northern sea of the Shandong Peninsula are mainly controlled by ENSO. A stronger ENSO led to increased TC activity in the region of genesis, resulting TC tracks shifting northward, which result in higher TC activity affected the BS.</p></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"474 ","pages":"Article 107311"},"PeriodicalIF":2.9,"publicationDate":"2024-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141145058","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":"Imprints of washover sediments by tropical storm Pabuk 2019 along the coast of the Gulf of Thailand; insight into coastal geomorphological response to storm surge","authors":"Chanakan Ketthong ,&nbsp;Sumet Phantuwongraj ,&nbsp;Montri Choowong ,&nbsp;Vichai Chutakositkanon","doi":"10.1016/j.margeo.2024.107321","DOIUrl":"10.1016/j.margeo.2024.107321","url":null,"abstract":"<div><p>Tropical storm Pabuk (4th January 2019) struck southern Thailand, causing damage to the low-lying coastal area. The combination of waves, storm surge, and high tide resulted overwash and inundation of regions on the West coast of the Gulf of Thailand (GOT) side. After the event, we conducted a field survey from January 7–10 and 15–20, 2019 to investigate the effect of storm surges and the degree of damage from the site under the eye of storm affected area up to the north 500 km from the landfall sites. This paper investigates how variations in coastal geomorphological features respond to the storm surge generated by tropical storm Pabuk at a regional scale. Coastal damage was observed along the beach from the presence of the scour, beach scarp, knocked down trees, and destroyed buildings and infrastructure. The most damaged area was at Nakhon Si Thammarat (NST), where the tropical storm made landfall with maximum wind speeds of almost 100 km/h and a storm surge height of 5 m. At NST site, the washover deposits extended as far as 80 m from the coastline with a maximum inundation of 330 m. From this study, two types of washover deposits including perched fan and washover terrace were identified. The thickest washover sediment, 60 cm thick, was discovered in a relatively low-lying area adjacent to a small estuary. Mud rip-up clasts, planar stratification, cross stratification, foreset bedding, scouring at base, and sharp and erosional contact are characteristics of sedimentary structures found in storm sediments. Bedform surfaces, such as current ripples with indicated storm surge direction, were well-preserved at several sites. We suggest that the local geomorphological controlling factors, especially coastal elevation have played important roles in the difference of coastal geomorphological responses as well as the type of washover deposits.</p></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"474 ","pages":"Article 107321"},"PeriodicalIF":2.9,"publicationDate":"2024-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141132320","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":"Molecular and radiocarbon constraints on the fate of sedimentary organic carbon in a human-impacted river-dominated ocean margin","authors":"Chenglong Wang ,&nbsp;Chuchu Zhang ,&nbsp;Zhuoyue Zhang ,&nbsp;Qihang Liao ,&nbsp;Yang Zhang ,&nbsp;Ning Wang ,&nbsp;Yaping Wang ,&nbsp;Xinqing Zou","doi":"10.1016/j.margeo.2024.107322","DOIUrl":"10.1016/j.margeo.2024.107322","url":null,"abstract":"<div><p>Organic carbon (OC) burial in river-dominated ocean margins plays a pivotal role in the global carbon cycle, impacting atmospheric CO₂ levels over the long term. Despite its significance, uncertainties persist regarding the influence of external environmental factors and intrinsic properties on sedimentary OC. In this study, we conducted a comprehensive analysis of surface sediments from the East China Sea, examining geochemical properties (including total OC content [TOC], Δ¹⁴C, δ¹³C, and C/N ratio), terrestrial biomarkers (<em>n</em>-alkanes), and mineral properties (such as specific surface area, Al/Si ratio, and mineral composition). Our aim was to shed light on the fate of sedimentary OC.</p><p>The surface sediment's Δ¹⁴C values displayed significant spatial heterogeneity, delineating four distinct sub-regions. Strong positive correlations (all <em>p</em> &lt; 0.01) were found between the ∆¹⁴C values and fine-grained sediments, specific surface area, and clay minerals, suggesting the potentially pivotal role of mineral protection in shaping the fate of sedimentary OC. The proportion of terrestrial OC gradually decreased towards the south, while marine OC proportion increased, corresponding to the enrichment of Δ¹⁴C. The co-variation of Δ¹⁴C values, mineral properties, and OC source proportions suggests that terrestrial OC may undergo progressive replacement by marine OC during southward transport. Temporal variations in ∆¹⁴C values indicated that seabed erosion led to a significant increase in ∆¹⁴C values (<em>p</em> &lt; 0.01) in the coastal mud belt, a phenomenon likely common in river-dominated ocean margins globally due to the new sediment cycle during the Anthropocene.</p></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"473 ","pages":"Article 107322"},"PeriodicalIF":2.9,"publicationDate":"2024-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141139935","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":"Sediment dynamics on a subtidal reef flat of an atoll in the South China Sea","authors":"Jin Li ,&nbsp;Andrew D. Ashton ,&nbsp;Ya Ping Wang ,&nbsp;Xiaomei Xu ,&nbsp;Shu Gao","doi":"10.1016/j.margeo.2024.107310","DOIUrl":"https://doi.org/10.1016/j.margeo.2024.107310","url":null,"abstract":"<div><p>Atolls in the South China Sea comprise 15% of the world's total in area. In contrast to most reef flats in the Indo-Pacific region, which typically develop up to contemporary sea level, a significant portion of their reef flats in the South China Sea are inundated at depths of 5–20 m. To gain insights into modern processes and determine whether these subtidal reef flats are actively shaped by hydrodynamics, we carried out an in situ observation on a 12 m-deep southwest-facing reef flat over a period of 8 months. The measurements revealed a prevalence of seasonally varying waves and stable tidal currents. While the reef flat remained sheltered from the northeast monsoon (January–May), the southwest monsoon (June–September) led to prolonged reef exposure to substantial waves (mean significant wave height of 1.3 m, with an orbital velocity of 0.22 m/s on average). Such an exposure resulted in the formation of mobile bed ripples and entrainment of coarse-grained coral sands. Estimates of potential bedload transport rate indicated that the combined action of waves and currents caused material loss from the reef flat, with movement into the lagoon or down the fore-reef slope of the atoll. This sediment loss was equivalent to reef bed erosion of up to 28 mm during the observation period. As these potential losses may be compensated by coral reef growth, our measurements implied that modern sediment budgeting has played a significant role in the maintenance of subtidal reef flats, in terms of bed elevation. Hence, the deep reef flat does not necessarily belong to the previously identified give-up pattern; a balance of coral sediment supply and transport-induced loss may result in an equilibrium morphology, or a “lock-up” pattern.</p></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"473 ","pages":"Article 107310"},"PeriodicalIF":2.9,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141097394","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":"Submarine morphology of Pantelleria volcano: The interplay between volcanic and erosive-depositional processes modulated by sea-level fluctuations.","authors":"Daniele Casalbore ,&nbsp;Claudia Romagnoli ,&nbsp;Marilena Calarco ,&nbsp;Alessandro Bosman ,&nbsp;Eleonora Martorelli ,&nbsp;Francesco Latino Chiocci","doi":"10.1016/j.margeo.2024.107308","DOIUrl":"https://doi.org/10.1016/j.margeo.2024.107308","url":null,"abstract":"<div><p>High-resolution multibeam data integrated with seismic reflection profiles are used to identify and characterize the main primary volcanic and erosive-depositional features along the submarine part (about the 80%) of the active Pantelleria volcano located in the Sicily Channel. Volcanic features include lava flows, cones and elongated ridges. Lava flows are mainly recognized over the insular shelf, while volcanic cones and ridges are mostly concentrated along the steep submarine flanks, especially along the wider SE and NW ones. A strong volcano-tectonic interaction is envisaged for their formation, as indicated by their preferential elongation or alignment along the (main) SE-NW and (secondary) SW-NE directions that have controlled the evolution of the whole volcanic edifice. Erosive-depositional features mainly include small-scale landslide scars and narrow gullies affecting the edge of the insular shelf and overlying submarine depositional terraces. Gullies sometimes merge downslope in larger channels, whose formation is primarily controlled by the distribution of volcanic features and/or shelf sectors characterized by different age or lithologies. Based on the marked morphological differences between the different flanks of the Pantelleria volcano, we infer an overall migration of the volcanic activity from SE to NW over time. This migration is apparently in contrast with the presence of a much wider but shallower NW insular shelf with respect to the SE one. This anomaly can be explained through a two-stage model, with the formation, in the NW sector, of a polygenic shelf rejuvenated by volcanic progradation during the last eustatic hemicycle. The different depths of the insular shelf edge around the island also provide insights on vertical deformations that affected the Pantelleria volcano during the Late-Quaternary.</p></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"472 ","pages":"Article 107308"},"PeriodicalIF":2.9,"publicationDate":"2024-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0025322724000926/pdfft?md5=8532dc035a0c5625583b2b02a754c63d&pid=1-s2.0-S0025322724000926-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141066843","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 adsorption of cerium on synthetic δ-MnO2: Implications for Ce uptake behavior of hydrogenetic and early diagenetic ferromanganese nodules from the Western Pacific","authors":"Yayue Tang ,&nbsp;Dengfeng Li ,&nbsp;Pete Hollings ,&nbsp;Xiaoming Sun ,&nbsp;Yongjia Liang ,&nbsp;Rui Wang ,&nbsp;Jinzhou Peng ,&nbsp;Yu Fu ,&nbsp;Pin Wang","doi":"10.1016/j.margeo.2024.107309","DOIUrl":"10.1016/j.margeo.2024.107309","url":null,"abstract":"<div><p>Cerium (Ce) anomalies can be used to distinguish diagenetic and hydrogenetic nodules, making them an important discriminator for the genesis of marine ferromanganese nodules. To understand the enrichment and adsorption mechanisms of Ce in different types of ferromanganese nodules, we conducted mineralogical and geochemical studies on ferromanganese nodule layers formed through both hydrogenetic and early diagenetic processes as well as adsorption experiments on synthetic δ-MnO₂ to monitor the Ce uptake during the different processes. The major and trace element contents of natural ferromanganese nodule layers were investigated by SEM, EPMA and LA-ICP-MS analysis. The marine nodule studied in this study consisted of a core of fish tooth and a rim that could be divided into the hydrogenetic (type I) and early diagenetic (type II) layers based on their mineralogy and Mn/Fe ratios. The Mn oxide mineral assemblage is composed of todorokite, buserite, birnessite, and vernadite (δ-MnO₂) and occurred in both type I and II layers. The type I layer has laminated structures with a low Mn/Fe ratio (1.1–3.2; averaging at 1.7), and low Cu, Ni and Mg contents consistent with a hydrogenetic genesis. The type II layer has a columnar and stromatolitic structure with a high Mn/Fe ratio (5.1–54.0; averaging at 23.3) and high Cu, Ni and Mg contents that are similar to early diagenetic nodules. The ΣREE contents in type I and type II layers are 1405–3506 ppm (averaging at 2091 ppm) and 199–1232 ppm (averaging at 674 ppm), respectively, indicating that the REE is enriched in the hydrogenetic type I layers. Strong positive Ce anomalies are present type I layers ranging from 1.2 to 2.5 (averaging 1.9), but only slightly positive are seen in type II ranging from 0.4 to 2.4 (averaging at 1.0). Synthetic experiments to monitor the Ce uptake process show that Ce can be adsorbed onto δ-MnO₂ with the XRD and FTIR patterns suggesting that the structure of δ-MnO₂ did not change significantly, consistent with Ce behavior in hydrogenetic nodules. The results suggest that Ce is predominantly concentrated in hydrogenetic nodules in an oxic environment, whereas in the early diagenetic layer, there is less oxidation and fixation of Ce due to the suboxic conditions. Our findings are consistent with Ce anomalies in marine Fe-Mn nodules being the result of Mn oxide oxidation adsorption and then fixation (oxidation) after adsorption.</p></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"473 ","pages":"Article 107309"},"PeriodicalIF":2.9,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141025165","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}