Geochemistry Geophysics Geosystems最新文献

{"title":"Evolving Fluid Source During the Growth of a Trench-Parallel Seismogenic Fault System","authors":"Simone Masoch,&nbsp;Luigi Dallai,&nbsp;Rodrigo Gomila,&nbsp;Michele Fondriest,&nbsp;Davide Novella,&nbsp;Giorgio Pennacchioni,&nbsp;José Cembrano,&nbsp;Giulio Di Toro","doi":"10.1029/2024GC011998","DOIUrl":"https://doi.org/10.1029/2024GC011998","url":null,"abstract":"<p>Fluid infiltration along seismically-active faults and fluid-rock interaction influence the mechanical behavior of faults. Nevertheless, how fluid infiltration and fluid-rock interactions evolve at seismogenic depths with fault slip accumulation remain poorly constrained in the geological record. We used hydrogen and oxygen isotope geochemistry to determine the origin of hydrous fluids that percolated within the exhumed Bolfin Fault Zone (BFZ)—a segment of the Early Cretaceous intra-arc Atacama Fault System (Northern Chile)—during progressive fault evolution at seismogenic depth. The BFZ consists of D₁ pseudotachylyte-bearing cataclastic strands linked by D₂ extensional to hybrid extensional-shear, epidote-rich fault-vein systems that formed in a fluid-rich, seismically active environment at 3–7 km depth and 200–300°C. The D₁ pseudotachylytes and cataclasites have δD values similar to, or slightly higher than, those of unaltered hydrogen-bearing magmatic minerals (−78‰ ≤ δD ≤ −56‰). This similarity indicates that seismic faulting occurred in a rock-buffered environment with limited circulation of external fluids at early stages of fault evolution. Conversely, the epidote of the D₂ fault-vein systems has much heavier δD compositions (−47‰ ≤ δD ≤ −9‰) and δ¹⁸O values ranging from 3.77 to 6.71‰, suggesting infiltration of shallow fluids, likely sourced from closed, marine-connected basins. Epidote-quartz oxygen isotope thermometry indicates equilibration at 200–220°C for this stage of fluid infiltration. The influx of external, basin-derived fluids within the BFZ is interpreted to indicate the increased hydraulic connectivity during slip accumulation and fault network growth.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 5","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011998","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144100775","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 Formation of Ferromanganese Crusts From the Western Mariana Ridge and Implications for Deep-Water Environment Since the Late Pliocene","authors":"Linzhang Wang,&nbsp;Zhigang Zeng","doi":"10.1029/2024GC011964","DOIUrl":"https://doi.org/10.1029/2024GC011964","url":null,"abstract":"<p>Pacific Deep Water (PDW) plays a crucial role in the dynamics of the global thermohaline circulation. Understanding the evolution of the PDW is significant to reveal the global carbon cycle and its climatic responses. We present a comprehensive study of ferromanganese crusts from the Western Mariana Ridge (WMR), which includes mineralogical and high-resolution geochemical data and Be isotopes. The mineralogical compositions are vernadite, quartz, anorthite, albite. calcite, sanidine and illite. Ferromanganese crusts on the Western Mariana Ridge are hydrogenetic in origin. We constrained the chronological framework using three Be isotope age control points at 3.04, 1.21, and 0.35 Ma. Based on the microstructure and geochemical variations of the ferromanganese crust, the PDW of the WMR can be divided into three stages: Stage I: 3.04 to 1.99 Ma, Stage II: 1.99 to 0.59 Ma, and Stage III: 0.59 Ma to present. These stages are influenced by paleoceanographic events such as Northern Hemisphere Glaciation (NHG), and the Mid-Pleistocene Transition (MPT). Global cooling may have been the main driving force affecting changes in the regional deep-water environment, thereby influencing the extent of the oxygen minimum zone (OMZ).</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 5","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011964","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144085414","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Origins and Alteration of Ediacaran Carbonates Recording the Shuram Excursion in Oman","authors":"Kristin D. Bergmann,&nbsp;Magdalena R. Osburn,&nbsp;Noah T. Anderson,&nbsp;Claire Hayhow,&nbsp;Julia Wilcots,&nbsp;Marjorie D. Cantine,&nbsp;Woodward W. Fischer,&nbsp;Magali Bonifacie","doi":"10.1029/2025GC012161","DOIUrl":"https://doi.org/10.1029/2025GC012161","url":null,"abstract":"<p>The Shuram excursion is the largest known negative carbon isotope excursion in Earth's history. Recognized globally, it follows the Ediacaran Gaskiers glaciation and precedes a marked increase in the diversity and complexity of the earliest macroscopic multicellular organisms in the fossil record. A key question is whether this excursion reflects a primary perturbation to the carbon cycle, which would provide crucial insights into the environmental conditions shaping the earliest animals, or whether it is largely an artifact of later diagenetic alteration. To evaluate the extent of diagenesis in these rocks and constrain how much of the excursion reflects a primary signal, we investigate the sedimentology and geochemistry of carbonate strata in Oman using a variety of techniques spanning multiple spatial and temporal scales. Our multi-faceted analysis identifies and characterizes four modes of diagenetic alteration, with sediment-buffered conditions and authigenic carbonate precipitation as the dominant processes. However, the degree of alteration is insufficient to account for the range of marine sedimentologic and geochemical trends across the carbon isotope excursion. This suggests that, even with evidence of diagenesis, the rocks preserve a measurable record of changing conditions in both terrestrial and marine environments, offering unique insights into Earth's systems during a pivotal time in early animal evolution.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 5","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GC012161","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143944451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Sensitivity Analysis of the Thermal Structure Within Subduction Zones Using Reduced-Order Modeling","authors":"Gabrielle M. Hobson,&nbsp;Dave A. May","doi":"10.1029/2024GC011937","DOIUrl":"https://doi.org/10.1029/2024GC011937","url":null,"abstract":"<p>Megathrust earthquakes are the largest on Earth, capable of causing strong ground shaking and generating tsunamis. Physical models used to understand megathrust earthquake hazard are limited by existing uncertainties about material properties and governing processes in subduction zones. A key quantity in megathrust hazard assessment is the distance between the updip and downdip rupture limits. The thermal structure of a subduction zone exerts a first-order control on the extent of rupture. We simulate temperature for profiles of the Cascadia, Nankai and Hikurangi subduction zones using a 2D coupled kinematic-dynamic thermal model. We then build reduced-order models (ROMs) for temperature using the interpolated Proper Orthogonal Decomposition (iPOD). The resulting ROMs are data-driven, model agnostic, and computationally cheap to evaluate. Using the ROMs, we can efficiently investigate the sensitivity of temperature to input parameters, physical processes, and modeling choices. We find that temperature, and by extension the potential rupture extent, is most sensitive to variability in parameters that describe shear heating on the slab interface, followed by parameters controlling the thermal structure of the incoming lithosphere and coupling between the slab and the mantle. We quantify the effect of using steady-state versus time-dependent models, and of uncertainty in the choice of isotherm representing the downdip rupture limit. We show that variability in input parameters translates to significant differences in estimated moment magnitude. Our analysis highlights the strong effect of variability in the apparent coefficient of friction, with previously published ranges resulting in pronounced variability in estimated rupture limit depths.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 5","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011937","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143938877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Demise of the Barra Honda Carbonate Shoal (Costa Rica) at the Paleocene-Eocene Boundary Linked to Climate Change and Forearc Tectonics","authors":"Goran Andjić,&nbsp;Claudia Baumgartner-Mora,&nbsp;Peter O. Baumgartner,&nbsp;Maria Rose Petrizzo,&nbsp;Torsten Vennemann,&nbsp;André N. Paul,&nbsp;Valentin Lorenzo","doi":"10.1029/2024GC012080","DOIUrl":"https://doi.org/10.1029/2024GC012080","url":null,"abstract":"<p>The latest Cretaceous(?)–Paleocene Barra Honda Formation represents one of the largest carbonate shoals (&gt;900 km², 350 m thick) of the convergent margin of Costa Rica. Although the mode of formation of the carbonate shoal is well understood, how environmental and tectonic factors interacted to cause its demise near the Paleocene-Eocene boundary remains poorly constrained. Stable isotopic, biostratigraphic, mineralogical, and geochronological analyses from the Barra Honda Formation and overlying siliceous Buenavista Formation provide new constraints on the timing and causes of the demise of the carbonate shoal. We report one new U–Pb zircon chemical abrasion, isotope dilution, and thermal ionization mass spectrometry date (56.30 ± 0.13 Ma, 2σ) obtained from an ash-rich layer at the boundary between the two formations. The sharp transition from Barra Honda massive limestones to Buenavista marl-chert alternations coincides with a negative shift in carbon isotope (δ¹³C_carb) values of about 3–5 ‰ and a 50% decrease in carbonate contents. The timing of the combined lithological-mineralogical-isotopic change is coeval with the Paleocene-Eocene Thermal Maximum (PETM, 56 Ma). The onset of clay-rich sedimentation is consistent with a PETM-related increase in the terrestrial influx of nutrients and detrital particles, which promoted eutrophication and decreased light availability in the photic zone. Combined with seawater acidification and warming, these environmental parameters were fatal to the carbonate-producing benthic communities of Barra Honda. High subsidence rates of the forearc basin and renewed arc volcanic activity must have closely followed the cessation of shallow carbonate production, preventing further formation of the carbonate shoal.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 5","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC012080","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143938880","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Relict Back-Arc Basin Crustal Structure in the Western Greater Caucasus, Georgia","authors":"Dylan A. Vasey,&nbsp;Eric Cowgill,&nbsp;Jill A. VanTongeren,&nbsp;Catherine O. Anderson","doi":"10.1029/2024GC012036","DOIUrl":"https://doi.org/10.1029/2024GC012036","url":null,"abstract":"<p>Back-arc basins frequently form within subduction zones, creating sources of lithospheric weakness that can accommodate subsequent compressional deformation. The crustal structure of these basins, including whether they contain extended preexisting crust and/or new crust formed by seafloor spreading, can thus exert a major influence on strain partitioning in orogenic belts. Here, we present field observations, petrographic analyses, and major/trace element geochemical data from the Caucasus Basin, a back-arc basin that initiated in continental lithosphere in the Jurassic and subsequently localized deformation in the present-day Greater Caucasus during the latter stages of Cenozoic Arabia-Eurasia continent-continent collision. Our results reveal distinct lithologic and geochemical domains separated by south-vergent thrust faults within the North Georgia fault system (NGFS) in the Republic of Georgia. Along the Enguri River, shallow intrusive and volcanic rocks are thrust over dominantly volcaniclastic cover, whereas along the Tskhenistskali River, intrusions into metasedimentary rocks are juxtaposed against volcanic flows. The presence of a minor depleted mantle geochemical signature in intrusive rocks from the Tskhenistskali traverse supports an episode of Jurassic seafloor spreading in the Caucasus Basin, with the resulting lithosphere facilitating Cenozoic basin closure by north-dipping subduction during Arabia-Eurasia collision. The Khaishi fault along the Enguri River and the Lentekhi fault along the Tskhenistskali river mark major juxtapositions in back-arc crustal structure and may be components of the terminal suture indicating Caucasus Basin closure. Our results highlight how magmatic rocks in relict basin rocks can yield key insights into basin structure and orogenesis, even when no ophiolite is present.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 5","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC012036","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143938864","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Melt-Supported Strain Localization at Eclogite-Facies Conditions Triggered by Syn-Metamorphic Strength Inversion","authors":"Anna Rogowitz,&nbsp;Simon Schorn,&nbsp;Benjamin Huet,&nbsp;Bernhard Grasemann,&nbsp;Luca Menegon","doi":"10.1029/2024GC012110","DOIUrl":"https://doi.org/10.1029/2024GC012110","url":null,"abstract":"<p>In convergent high-pressure settings dominated by dry mafic rocks, strain has been proposed to be predominantly localized in eclogite. However, the processes initiating strain localization, accommodating strain and rheological consequences remain to be identified. We combine field, microstructural, petrographic and geochemical data to investigate the origin of strain localization under eclogite-facies conditions. The studied shear zone bears rocks with two eclogite-facies mineral assemblages: The host-rock eclogite contains clinopyroxene, garnet, zoisite, amphibole, quartz, kyanite and rutile, in which sigmoidal enclaves dominated by zoisite, hornblende and garnet occur. Protolith assemblage calculations suggest that enclaves have originally been plagioclase-rich cumulates within a gabbro. Strength estimates indicate that the enclaves were initially less competent than the gabbro. However, the sigmoidal shape of the enclaves surrounded by ultramylonitic eclogite suggests that the enclaves were stronger during shear zone development. Microstructural investigations of the ultramylonitic eclogite reveal a fabric dominated by euhedral clinopyroxene. Triple- and quadruple-junctions and melt traces at grain boundaries suggest that eclogite is dominantly deformed by melt-supported grain boundary sliding. On the other hand, the microstructure of the lenses is dominated by elongated zoisite and sigmoidal amphibole aggregates deforming by combined dislocation creep and diffusion-mediated grain growth. Our findings demonstrate that high-pressure metamorphism led to a strength inversion, with lenses initially weaker than their host becoming stronger during eclogite-facies metamorphism. Strength-inversion initiated stress concentration at the lithological contact and subsequent strain localization in the weaker eclogitic mineral assemblage. Our results highlight the critical role of compositional heterogeneities on strain localization at high pressures.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 5","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC012110","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143932376","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Elemental Geochemistry of Tidal Marsh Sediment and Its Potential as an Indicator of Sea-Level Change in Cascadia","authors":"Anthony Giang,&nbsp;Jessica E. Pilarczyk,&nbsp;Isabel Hong,&nbsp;Louise Riou,&nbsp;David Huntley,&nbsp;Roger MacLeod,&nbsp;Owen G. Ward,&nbsp;John J. Clague,&nbsp;Peter Bobrowsky,&nbsp;Andrea D. Hawkes,&nbsp;Simon E. Engelhart,&nbsp;Benjamin P. Horton","doi":"10.1029/2024GC012129","DOIUrl":"https://doi.org/10.1029/2024GC012129","url":null,"abstract":"<p>Holocene sea-level reconstructions from tidal marshes are commonly derived from proxy indicators that have a consistent and quantifiable relationship with tidal elevation. While microfossils are most commonly employed, using multiple indicators leads to more robust reconstructions. We explore the utility of elemental geochemistry obtained through x-ray fluorescence as a proxy indicator in tidal marshes at Port Alberni, British Columbia, Canada and Willapa Bay, Washington, United States. The elemental composition of bulk surface sediment collected from 141 stations along 10 transects was determined using an ITRAX Core Scanner. Partitioning Around Medoids cluster analysis on the elemental data distinguished between tidal flat, low marsh, and high marsh zones at both locations, similar to zones established from previously published microfossil (foraminifera, diatoms) data sets on the same samples. The elemental composition of low elevation samples from the tidal flat is dominated by lithogenic (Si, K, Ti, Fe) and biogenic (Sr) elements, whereas higher elevation samples have high proportions of organic content (Br, incoherent and coherent scattering ratio). Principal Component Analysis points to differences in organic versus inorganic content, a function of tidal elevation, as the main driver of geochemistry-derived zones. Approximately 70% of the elemental variability within both marshes is controlled by the inorganic content, as indicated by lithogenic and biogenic elements versus organic content. The elemental composition of bulk surface sediment from two regions spaced ∼300 km apart shows a promising relationship with tidal elevation over a wider spatial scale and highlights the potential of this proxy for use in sea-level reconstructions.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 5","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC012129","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143925788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"How Do Passive Margins Convert to Active Margins?","authors":"Timothy M. Kusky,&nbsp;Junpeng Wang","doi":"10.1029/2025GC012394","DOIUrl":"https://doi.org/10.1029/2025GC012394","url":null,"abstract":"<p>There has been a long debate about how passive (Atlantic-type) margins can convert to active (Andean) margins, particularly if they can do so directly, or some other process such as an arc-continent collision must intervene (Burke et al., 1984; Dewey, 1969, https://doi.org/10.1016/0012-821x(69)90089-2; Kusky &amp; Kidd, 1985). Most numerical models have long-suggested that only very young passive margins can be sites of subduction initiation since old margins become stronger as they cool and develop thick sedimentary piles during thermal subsidence (e.g., Cloetingh et al., 1982, https://doi.org/10.1038/297139a0, 1989, https://doi.org/10.1007/bf00874622; 1996; Zhong &amp; Li, 2019, https://doi.org/10.1029/2019gl084022), whereas other analog and numerical models have suggested that old passive margins may spontaneously convert to subduction zones (e.g., Bercovici &amp; Mulyukova, 2021, https://doi.org/10.1073/pnas.2011247118; Faccenna et al., 1999, https://doi.org/10.1029/1998jb900072; Nikolaeva et al., 2010, https://doi.org/10.1029/2009jb00654; Stern &amp; Gerya, 2018, https://doi.org/10.1016/j.tecto.2017.10.014; Zhang et al., 2023, https://doi.org/10.1029/2023gl103553).</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 5","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GC012394","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143925789","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Late Cenozoic Rise in Seawater δ11B Not Driven by Increasing Boron Adsorption","authors":"Simon J. Ring,&nbsp;Michael J. Henehan,&nbsp;Patrick J. Frings,&nbsp;Roberts Blukis,&nbsp;Friedhelm von Blanckenburg","doi":"10.1029/2024GC011911","DOIUrl":"https://doi.org/10.1029/2024GC011911","url":null,"abstract":"<p>The boron isotopic value of ancient seawater (δ¹¹B_sw) is a prerequisite for the reconstruction of seawater pH and atmospheric CO₂ concentrations. Available models and some proxy records suggest that δ¹¹B_sw underwent a large increase during the last 45 million years. This increase has been attributed to an acceleration in sediment discharge into the ocean and the enhanced adsorption of boron on particle surfaces. However, whether global sedimentation rates have increased in the late Cenozoic is contested. Additionally, adsorption efficiency was likely modulated by secondary factors related to seawater chemistry and the sedimentary mineral content, that could have counteracted changes in sedimentation rates. Here we revisit the controls on boron adsorption over the last 100 million years. We found that changes in the seawater concentration of dissolved inorganic carbon (HCO₃⁻, CO₃²⁻) and major ions (Ca²⁺, Mg²⁺, SO₄²⁻) had a negligible impact on boron adsorption. Instead, the sedimentary mineral assemblage and the acidity of seawater were important subordinate factors. By considering several possible sediment production scenarios, we propose that the ability of sediment to adsorb boron was lower in the Cretaceous but has remained similar to the present-day since the Eocene. When these results are incorporated into a seawater model, δ¹¹B_sw exhibits a step-wise enrichment over the Cenozoic, that is, at times, 2‰ above previous model results. Our analysis precludes a dominant role of adsorption in the boron isotope cycle of the late Cenozoic, but nevertheless supports the view that δ¹¹B_sw was lower than today for the last 60 million years.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 5","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011911","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143925790","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}