Marine Geology最新文献

{"title":"Distribution of biochemical components in sedimentary organic matter of a Coastal Wetland: Anthropogenic and detrital influences","authors":"Eleonora M. Fernández ,&nbsp;Carla V. Spetter ,&nbsp;Mariana Gentile ,&nbsp;Diana M. Villagrán ,&nbsp;Ana M. Martínez ,&nbsp;Natalia S. Buzzi","doi":"10.1016/j.margeo.2025.107657","DOIUrl":"10.1016/j.margeo.2025.107657","url":null,"abstract":"<div><div>Coastal wetlands, particularly tidal flats, play a crucial role in carbon sequestration and nutrient cycling in temperate environments. This study investigates the biochemical composition of sedimentary organic matter (SOM) in the tidal flats of Puerto Rosales (Bahía Blanca Estuary, Argentina), emphasizing the dual influences of natural processes and anthropogenic activities. Sampling was conducted seasonally (2014–2015) at two sites: ST1, an intertidal zone affected by untreated sewage discharge, and ST2, a supratidal zone dominated by microbial mats. Surface (0–5 mm) and subsurface (5–10 mm) sediment layers were analyzed to assess early diagenetic processes, SOM component and trophic status. Results indicated that the organic carbon (OC) in sediments was predominantly non-biogenic, with proteins as the major component of the labile fraction, influenced by seasonal phytoplankton blooms and urban discharges. While the tidal flat exhibited meso-oligotrophic to eutrophic conditions, refractory material dominated over labile fractions (proteins and carbohydrates). Additionally, distinct spatial and seasonal variations in SOM quality and composition, linked to redox conditions and organic detrital quality were observed.These findings underscore the ecological importance of Puerto Rosales tidal flats as dynamic systems for carbon storage and nutrient recycling. They highlight the need for sustainable management strategies to mitigate anthropogenic pressures and preserve the critical ecosystem functions of these coastal wetlands.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"490 ","pages":"Article 107657"},"PeriodicalIF":2.2,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145096742","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 impact of mangroves development and morphodynamics on channel function shift and flow asymmetry in an estuarine channel-shoal system","authors":"Amin Rahdarian ,&nbsp;Karin R. Bryan ,&nbsp;Mick Van Der Wegen","doi":"10.1016/j.margeo.2025.107658","DOIUrl":"10.1016/j.margeo.2025.107658","url":null,"abstract":"<div><div>Estuarine channels convey tidal flow and sediments, while the direction and magnitude of tide-residual transports largely depends on the surrounding estuarine bathymetry, shoals and vegetation cover. This study explores the controls of historic morphodynamics, mangrove development and channels on landscape-scale tidal hydrodynamics around a mangrove-covered estuarine shoal in Whitianga estuary, Aotearoa New Zealand. A Delft3D hydrodynamic model was used to explore the impact of historic developments on spatial flow patterns and flow asymmetry based on an analysis of historical images of the site including conditions of the mangrove forest in the 1940s.</div><div>Model results clearly reveal areas of ebb and flood dominance in the model domain, where mangrove surrounded creeks are ebb dominant and shoal incising channels are flood dominant. Within the forest, the seaward part of mangroves is ebb-dominant, whereas a flood-dominance function in the back of the forest with higher elevated mangroves is mostly observed. Removing vegetation leads to a large-scale change in flow routing and flow asymmetry, whereas if creeks are infilled, local changes only around the location of the creeks are observed.</div><div>The movement of fine sediment fractions is inferred by the slack water duration at high tide. The existence of vegetation affects the cohesive fraction. Without vegetation, the slack water duration becomes shorter on the shoal close to the fringe, inside and the edge of the former forest while it becomes longer inside the river channel and on the edge of the shoal close to the river channel. In the scenario that channels were infilled, a longer (shorter) slack water duration at the mouth and head of channels and inside channels (around the channels) were observed.</div><div>Expansion of mangroves can cause a function shift of the channels. Model results suggest that the ebb-dominant modern-day mangrove creek was flood-dominant in 1940s prior to colonization of mangroves in the inner bend of the shoal.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"490 ","pages":"Article 107658"},"PeriodicalIF":2.2,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145096739","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":"Mabahiss Deep in the Northern Red Sea: New insights from high-resolution bathymetric mapping and analysis","authors":"Margherita Fittipaldi ,&nbsp;Daniele Trippanera ,&nbsp;Nico Augustin ,&nbsp;Froukje M. van der Zwan ,&nbsp;Laura Parisi ,&nbsp;Sigurjón Jónsson","doi":"10.1016/j.margeo.2025.107645","DOIUrl":"10.1016/j.margeo.2025.107645","url":null,"abstract":"<div><div>The northern Red Sea is largely floored by evaporites, covering its basement structure and associated lithology of the lithosphere. The basement is exposed at only a few locations, called “Deeps”. Mabahiss Deep is the largest deep in the northern Red Sea. It hosts a large submarine volcano, Mabahiss Mons, and lies north of the Zabargad Fracture Zone. We use new high-resolution bathymetric data, ROV images, and basalt sample analysis to map the morphology of the Mabahiss Deep to understand the volcano-tectonic setting of this area and study its geologic evolution, providing insights into a young ocean basin that is potentially representative of other ultra-slow spreading ridges worldwide. Our results show that Mabahiss Deep is a 2360 m deep axial valley bordered by NW-SE Red Sea axis-parallel normal faults. The Mabahiss Mons has a ∼2 km summit caldera containing columnar basalts at its footwall, volcanic cones with pillow lavas, and extensive lava flows indicating Holocene activity. The basaltic submarine caldera is rare in such settings but is consistent with considerable lava flows and high melt supply due to magma focusing and elevated heat flux in the Red Sea, in spite of the slow spreading rates. The rock samples analysis shows MORB-type composition without any interaction of continental crust. Together our results show that Mabahiss Deep is a typical mid-oceanic ridge segment, confirming that oceanic spreading processes are occurring in this part of the northern Red Sea.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"490 ","pages":"Article 107645"},"PeriodicalIF":2.2,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145047049","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":"Intelligent prediction of sediment floc settling velocity: Employing explainable machine learning and quantifying the impacts of environmental factors","authors":"Jinglun Huang,&nbsp;Zhixin Cao,&nbsp;Leiping Ye,&nbsp;Jie Ren,&nbsp;Jiaxue Wu","doi":"10.1016/j.margeo.2025.107631","DOIUrl":"10.1016/j.margeo.2025.107631","url":null,"abstract":"<div><div>Settling velocity of flocs resulting from cohesive sediment flocculation, significantly influenced by hydrological factors (e.g., turbulence shear, salinity, suspended sediment concentration and sediment size), is a key parameter to evaluate sediment transport in estuarine and coastal ocean. Measurement and prediction of in-situ settling velocity for sediment flocs are challenging at current stage due to the complex estuarine dynamics and technique constraints. A powerful and interpretable prediction model is urgently required. To meet this requirement, we propose a new paradigm in predicting settling velocity with interpretable machine learning (ML) model by combination of ML with Shapley additive explanation (SHAP) using 4 hydrological parameters as independent input features. Eight ML algorithms (including recently proposed XGBoost, LightGBM and so on) and ensemble learning (Stacking) were employed, with Bayesian Optimization Algorithm to determine the hyper-parameters. XGBoost model was found to have the highest prediction accuracy in terms of 6 performance metrics, among the 8 base learners. Stacking of these models outperform each component model. With the powerful SHAP methods, the proposed paradigm is able to interpret/explain ML model predictions and highlight the highly influential features for the system of sediment dynamics in both local and global points of view. Additionally, the developed ML model provides transparent insights into the contribution of each feature without compromising predictive accuracy. These ML-based models outperform conventional modified Stokes law or empirical equations. Specially, physics-informed neural network (PINN) is employed for prediction of floc settling velocity, which is also a useful approach to overcome the limitations of data driven model characterized by black box. Combinations of ML with physical law and SHAP, the key of the proposed paradigm, could be very powerful tool for researchers on sediment transport.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"489 ","pages":"Article 107631"},"PeriodicalIF":2.2,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144826358","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 provenance shifts in the South Yellow Sea: Implications of reduced river discharges over the past 60 years","authors":"Jian Lu ,&nbsp;Anchun Li ,&nbsp;Jin Zhang ,&nbsp;Xiaochuan Ma","doi":"10.1016/j.margeo.2025.107638","DOIUrl":"10.1016/j.margeo.2025.107638","url":null,"abstract":"<div><div>The Yellow River and Yangtze River significantly influence the South Yellow Sea (SYS) through sediment discharges. Over the past several decades, sediment loads from these rivers into the sea have dramatically decreased due to climate change and intensified human activities. However, there is limited understanding of how this reduction in river discharge might affect the provenance of sediments in the SYS. To address this, surface sediment samples were collected at identical stations in the SYS during two periods: 1958 and 2012. Grain size analysis revealed notable differences: in 2012, clay content decreased, and silt increased, resulting in coarser sediments compared to 1958. Provenance analysis revealed that the fine-grained surface sediments in the SYS were primarily derived from the Yellow and Yangtze Rivers, as evidenced by clay mineral compositions (illite, smectite, kaolinite, and chlorite) and element ratios (Ti/Al vs. Ti/Zr, and Ti/Zr vs. La/Hf). Interestingly, despite reduced sediment loads, the influence of the Yellow River expanded, while the influence of the Yangtze River decreased between 1958 and 2012. These changes in provenance are attributed to differences in sediment transport mechanisms from each source to the SYS. Reduced Yangtze sediment load led to decreased deposition off the Jiangsu coast during summer, limiting Yangtze-derived sediments in the SYS during winter. Conversely, resuspended sediments from the modern and old Yellow River subaqueous deltas provided continuous supply of material to the SYS. This study provides valuable insights into source-to-sink processes in marginal seas, particularly as global rivers continue to experience reductions in sediment discharge.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"489 ","pages":"Article 107638"},"PeriodicalIF":2.2,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144889147","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":"Sea level changes and the Indian Summer Monsoon influence on chemical weathering and sediment deposition on the Ninetyeast Ridge over the past 21 ka","authors":"Md. Sazzad Hossen ,&nbsp;Jianguo Liu ,&nbsp;Yun Huang ,&nbsp;Md Hafijur Rahaman Khan ,&nbsp;Bin Wang","doi":"10.1016/j.margeo.2025.107632","DOIUrl":"10.1016/j.margeo.2025.107632","url":null,"abstract":"<div><div>The sediment core retrieved from the Ninetyeast Ridge (NER) provides valuable insights into the interplay between chemical weathering processes and sediment deposition patterns in the marine environment. This interplay is strongly influenced by fluctuations in sea level and variations in the Indian Summer Monsoon (ISM). In this study, geochemical analyses of elemental compositions suggest that the Last Glacial Maximum (LGM) (∼21–19 ka) was a period of enhanced chemical weathering, likely driven by lowered sea levels and intensified glacial or aeolian activity. Concurrently, high surface productivity and reduction in bottom-water oxygenation favored the accumulation of organic carbon in the sedimentary record. In contrast, the deglacial period (∼17–11 ka) was characterized by rapid sea-level rise and dynamic monsoon evolution. This interval generally exhibited oxic bottom-water conditions, except for the Bølling–Allerød (B/A) interstadial. During the B/A event, increased sedimentation rates coincided with elevated paleoproductivity and suboxic marine conditions. The Holocene epoch reflects a shift, as rising sea levels and intensified ISM activity promoted enhanced chemical weathering in source regions. Notably, the Holocene Climatic Optimum (HCO) stands out as a period when increased solar insolation and strengthened monsoon circulation within the Indo-Pacific Warm Pool contributed to bottom-water deoxygenation and increased marine productivity. These findings highlight the intricate coupling between sea-level fluctuations and monsoonal forcing in modulating chemical weathering regimes and deep-sea sedimentation dynamics in the Indian Ocean basin.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"489 ","pages":"Article 107632"},"PeriodicalIF":2.2,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144757978","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":"Sedimentary processes in transport-limited versus weathering-limited erosional regimes: Contrasting mineralogical and geochemical signatures of sand and mud in Hainan and Taiwan islands","authors":"Jie He ,&nbsp;Eduardo Garzanti ,&nbsp;Tao Jiang ,&nbsp;Entao Liu ,&nbsp;Marta Barbarano ,&nbsp;Alberto Resentini ,&nbsp;Hua Wang","doi":"10.1016/j.margeo.2025.107635","DOIUrl":"10.1016/j.margeo.2025.107635","url":null,"abstract":"<div><div>This study provides and discusses an integrated petrographic, heavy-mineral, clay-mineral, elemental-geochemistry and Sr-Nd isotope-geochemistry dataset on sand and mud transported by mountain rivers in Hainan Island, where sand composition is mainly feldspatho-quartzose to quartz-rich feldspatho-quartzose, with K-feldspar invariably prevailing over plagioclase. Illite associated with chlorite prevails in the west, whereas kaolinite prevails in the north and northeast, underscoring a gradient of eastward-increasing weathering intensity in close correspondence with the progressive eastward increase in monsoonal rainfall.</div><div>All sand samples are enriched in SiO₂ relative to the upper continental crust and consequently depleted in most other chemical elements. The order of element mobility indicated by α^Al values is Mg &gt; Ca &gt; Na &gt; Sr &gt; K ≈ Ba ≈ Rb. The ⁸⁷Sr/⁸⁶Sr ratio varies between 0.717 and 0.721, and εNd ranges from −6.7 to −9.6. Moderately negative εNd and relatively high ⁸⁷Sr/⁸⁶Sr point at a significant contribution from old crystalline basement, directly or through recycling of siliciclastic strata.</div><div>Two endmember types of short river systems can be distinguished in eastern Asia, one dominated by chemical weathering controlled by tropical monsoonal climate under a tectonically stable background and gentle topography (transport-limited regime, dominant in Hainan Island) and another dominated by provenance-controlled physical erosion under a tectonically active background and rugged topography (weathering-limited regime, dominant in Taiwan Island). Mineralogical and geochemical information obtained from river sediments in these contrasting regimes can be profitably used in paleo-climatic inferences and reconstructions.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"489 ","pages":"Article 107635"},"PeriodicalIF":2.2,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144826359","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":"A thousand-year journey of lithification: CT-analysis and radiocarbon dating of algal reef from Central Mediterranean","authors":"Pietro Bazzicalupo ,&nbsp;Valentina Alice Bracchi ,&nbsp;Mara Cipriani ,&nbsp;Adriano Guido ,&nbsp;Antonietta Rosso ,&nbsp;Rossana Sanfilippo ,&nbsp;Francesco Maspero ,&nbsp;Anna Galli ,&nbsp;Elena de Ponti ,&nbsp;Daniela Basso","doi":"10.1016/j.margeo.2025.107637","DOIUrl":"10.1016/j.margeo.2025.107637","url":null,"abstract":"<div><div>Calcareous algal reefs are Mediterranean carbonate structures, formed by coralline red algae, that display early lithification and preserve key geobiological records. These structures exhibit complex three-dimensional frameworks influenced by environmental conditions and biological interactions, but their lithification processes, porosity evolution, and long-term growth patterns remain poorly understood. In this study, we use Computed Tomography (CT) scanning and radiocarbon dating on four coralligenous build-ups collected along a depth gradient offshore Marzamemi, SE Sicily, to investigate internal skeletal density, porosity distribution, and age profiles. Our findings reveal that lithification progresses gradually from High-Density (HD) to Ultra-High-Density (UHD) material, correlating inversely with porosity. Radiocarbon dating indicates a lithification timeline of roughly 1000 years, with the oldest, densest material dating back over 5000 years. The structures demonstrate a depth-density and age-depth gradient: deeper and older build-ups exhibited higher quantity of UHD material, whereas younger, shallower build-ups contain a higher proportion of HD material. Additionally, evidence suggests that specific build-ups may have been fragmented and relocated due to environmental or anthropogenic factors, further influencing growth patterns. The CT-analysis contributes to improving knowledge on coralligenous reef formation and evolution, underscoring the role of lithification in maintaining structural stability over millennia and providing insights applicable to the study of fossil reef systems.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"489 ","pages":"Article 107637"},"PeriodicalIF":2.2,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144908901","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":"Dating ‘Zebra’: A subaerial to ultra-shallow marine Lomonosov Ridge at the end of the Oligocene?","authors":"Francesca Sangiorgi ,&nbsp;Evi Wubben ,&nbsp;Suning Hou ,&nbsp;Henk Brinkhuis","doi":"10.1016/j.margeo.2025.107618","DOIUrl":"10.1016/j.margeo.2025.107618","url":null,"abstract":"<div><div>Twenty years after the pioneering IODP Expedition 302 (ACEX) to the Lomonosov Ridge, central Arctic Ocean, a robust age model was still lacking. This was foremost due to the overall poor core recovery, and frequent lack of age diagnostic features including (micro)fossils, notably in the likely Neogene succession. Interestingly, one of the few intervals that were relatively well-recovered was interpreted to span the Paleogene-Neogene transition. On board and follow up marine palynological studies indicated that within this interval, a potential ∼26 Myr long hiatus separated the local top of the Paleogene (∼44 Ma) from the Neogene (∼18 Ma), occurring between local lithological subunits 1/6 and 1/5. The latter was informally also referred to as the ‘<em>Zebra</em>’ interval, owing to its characteristic black/white alternations in the colour of the sediments. This hiatus would possibly imply a subaerial or ultra-shallow marine Lomonosov Ridge during late Oligocene to early Miocene times. A Neogene, (late) Early Miocene age for the base of ‘<em>Zebra’</em> subunit 1/5 was tentatively provided by the finding of a new, later formally described, organic walled dinoflagellate cyst (dinocyst) genus we named <em>Arcticacysta</em>, which included two species, <em>A. backmanii</em> and <em>A. moraniae</em>. Subsequent work challenged the presence of a hiatus and the age of the ‘<em>Zebra’</em> subunit.</div><div>Here we present recent palynological (dinocyst) findings from Miocene sediments retrieved from the Pennell Basin during IODP Expedition 374 (Ross Sea, Antarctica) that contain the first appearance at 17.7 Ma of specimens of the same dinocyst genus, <em>Arcticacysta</em>, and species, and a more continuous presence between 17.0 and 15.9 Ma. Providing that the (first) occurrence of this dinocyst genus is synchronous in both (polar) records, these findings confirm the assignment of the Arctic Ocean ‘<em>Zebra</em>’ interval to the (late) Early Miocene, adding evidence for a large hiatus characterizing the Paleogene/Neogene transition on the Lomonosov Ridge.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"489 ","pages":"Article 107618"},"PeriodicalIF":2.2,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144750477","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 coccolithophore productivity trends over the last 22,000 years: insights from sediments of IODP Expedition 385 in a high-productivity oceanic basin (Guaymas Basin)","authors":"María-Carmen Álvarez ,&nbsp;Ligia Pérez-Cruz ,&nbsp;Jaime Urrutia-Fucugauchi ,&nbsp;Alejandro Aldama-Cervantes ,&nbsp;Mauricio Velázquez-Aguilar ,&nbsp;Mariem Saavedra-Pellitero ,&nbsp;Miguel-Ángel Díaz-Flores","doi":"10.1016/j.margeo.2025.107629","DOIUrl":"10.1016/j.margeo.2025.107629","url":null,"abstract":"<div><div>We study sediment cores retrieved during International Ocean Discovery Program (IODP) Expedition 385 to gain a deeper understanding of the Guaymas Basin's (GB) response to climate fluctuations over the past 22,400 years by analyzing coccolithophore assemblages and estimating net primary productivity (NPP). Coccolithophore-based data and the NPP at IODP Hole 1549 A reveal that the GB consistently remained an area of high productivity throughout the studied time interval, with an average productivity value of 1288.25 mgC m⁻² day⁻¹, with a gradually declining trend towards the present.</div><div>Three main intervals are defined: (I) Cold, high productivity and vertically mixed surface waters during the Last Glacial Maximum and Heinrich Event 1 (22,400–15,320 cal yr BP), suggested by elevated net primary productivity (NPP), high abundance of <em>Gephyrocapsa oceanica</em>, and the presence of <em>Coccolithus pelagicus</em> subsp. <em>braarudii</em>. These conditions may be related to the incursion of the California Current Water into the GB. (II) Intermittent stratification with a deep position of the nutricline and thermocline during Bølling-Allerød, Younger Dryas, and broadly, the beginning of the Holocene (15,320–11,200 cal yr BP) indicated by an increase in relative abundance of <em>Florisphaera profunda</em> and the decrease in key coccolithophore taxa (notably <em>G. oceanica</em> and <em>C. pelagicus</em> subsp. <em>braarudii</em>). (III) Recurrent events of low productivity, warm surface water conditions with stratification since the beginning of the Holocene Climatic Optimum (11,200 cal yr BP-present), as suggested by the dominance of warm and oligo-mesotrophic water taxa (<em>Helicosphaera</em> spp., <em>Calcidiscus leptoporus</em>, <em>Syracosphaera</em> spp. and <em>Umbilicosphaera sibogae</em>) alongside a rise in <em>F. profunda</em>. From approximately 4900 cal yr BP to the present sustained stratification and declining NPP suggest the onset and intensification of modern monsoonal dynamics in the GB.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"489 ","pages":"Article 107629"},"PeriodicalIF":2.2,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144779951","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}