Geochemistry Geophysics Geosystems最新文献

{"title":"A Graphical User Interface Application to Model Open-System Melting in the Upper Mantle","authors":"I. Nishio,&nbsp;N. Akizawa,&nbsp;K. Ozawa,&nbsp;K. Itano,&nbsp;P. Waterton","doi":"10.1029/2026GC013081","DOIUrl":"https://doi.org/10.1029/2026GC013081","url":null,"abstract":"<p>The mantle partial melting process is crucial for the physicochemical evolution of the Earth's upper mantle and the generation of mafic crust. The open-system melting model incorporates continuous melt segregation, interaction with melts or fluids, and crystallization of trapped melt and therefore provides a comprehensive model for simulating mantle melting. Despite its broad capability, the model is difficult to apply because it requires complex parameter settings. We developed <i>osm.R</i>, a graphical user interface application that enables users to conduct open-system melting models without coding. Several tools within <i>osm.R</i> support both beginners and experienced users, making the model accessible while maintaining functionality. The application can simulate trace-element behavior in residues and melts across a wide range of melting conditions and can also perform best-fit estimation against observed data to constrain melting processes. Applying <i>osm.R</i> to clinopyroxene from abyssal peridotites confirms that the open-system melting model can reproduce natural clinopyroxene REE patterns by optimizing the degree of melting, critical melt fraction, and melt influx rate. The melting degrees estimated by simultaneously constraining critical melt fraction and melt influx rate are more reliable than those calculated from Yb contents in clinopyroxene by assuming fractional melting. The systematic change in the critical melt fraction with increasing melting degree may reflect progressive changes in melt separation efficiency beneath mid-ocean ridges. This highlights how <i>osm.R</i> strengthens the application of open-system melting models and improves our understanding of mantle melting in open systems.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"27 8","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026GC013081","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148784724","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":"Carbonate Clumped Isotopes (Δ47) in Cenozoic “Island Dolostones”: Dolomitization Driven by Modified Seawater at Earth-Surface Conditions","authors":"Cole A. McCormick,&nbsp;Brian Jones,&nbsp;Ellen K. Olsen,&nbsp;Miquela Ingalls","doi":"10.1029/2026GC013142","DOIUrl":"https://doi.org/10.1029/2026GC013142","url":null,"abstract":"<p>Dolomite [CaMg(CO₃)₂] is abundant throughout the geological record and constitutes a major component of many ancient carbonate platforms, yet the mechanisms responsible for its formation under Earth-surface conditions are equivocal. Given that modern examples of low-temperature dolomitization are rare, Cenozoic “island dolostones” provide ideal natural laboratories to evaluate these diagenetic processes. Sedimentological, petrographical, and geochemical studies indicate that “island dolostones” formed from seawater-derived fluids, but the temperature of dolomitization and the oxygen isotopic composition of the diagenetic fluids (δ¹⁸O_FLUID) remain poorly constrained. Using carbonate clumped isotope (Δ₄₇) thermometry, we demonstrate that the “interior” dolostones on Grand Cayman formed at higher temperatures (TΔ₄₇ = 26.1 ± 2.6°C), from diagenetic fluids with higher δ¹⁸O_FLUID values (2.1 ± 0.7‰ VSMOW), than the “peripheral” dolostones on Grand Cayman and Cayman Brac (TΔ₄₇ = 19.1 ± 1.4°C; δ¹⁸O_FLUID = 0.2 ± 0.5‰ VSMOW). Our results identify two endmember dolostone populations, consistent with dolomitization by evaporatively modified seawater in the platform interior and normal seawater along the platform margin. These observations are most readily explained by the migration of diagenetic fluids from restricted lagoonal settings toward the platform margin, where they mixed with seawater. Critically, isolated carbonate platforms host spatially heterogeneous diagenetic fluids that, when properly constrained, provide a powerful window into the geological record, thus strengthening interpretations of ancient seawater chemistry.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"27 8","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026GC013142","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148784723","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":"Hydrothermal Manganese-Oxide Mineralization of a Carbonate Ooze, Samoan Hotspot Region, South Pacific Ocean","authors":"James R. Hein,&nbsp;Amy Gartman,&nbsp;Kira Mizell,&nbsp;Mark Baskaran,&nbsp;Anthony Koppers,&nbsp;Hubert Staudigel","doi":"10.1029/2026GC012955","DOIUrl":"https://doi.org/10.1029/2026GC012955","url":null,"abstract":"<p>Low-temperature hydrothermal manganese oxides occur throughout the global oceans. However, the hydrothermal replacement of a carbonate ooze by manganese oxides is described here for the first time. The 24 samples dredged from three locations around the Territory of American Samoa in the South Pacific Ocean include six samples with remnant carbonate and volcaniclastic sediments, which we refer to as “low Mn,” and 18 samples in which the mineralization is pervasive and has replaced most original sediment, termed “high Mn.” The 18 high-Mn samples exhibit a mean Mn content of 51 wt.%. Higher Li and Mn contents and lower Fe contents in the high-Mn samples indicate a hydrothermal origin and distinguish these samples from hydrogenetic ferromanganese crusts. Mn-oxide layers are up to 90 mm thick, some with columns to 44 mm long and 10 mm wide, the magnitude of which has not been described previously. Samples are composed of birnessite and 10 Å phyllomanganate minerals. Textures of the thickest Mn layers indicate mineralization below the seabed from ascending fluids during multiple hydrothermal pulses. Mineralization took place by complete to partial replacement and cementation of foraminiferal sediments intermixed with volcaniclastic sediments in varying amounts. Our results highlight the production of carbonate sediment-hosted hydrothermal Mn oxides from multiple hydrothermal sources within the Samoan volcanic chain. The potential extensive distribution on the regional scale of this newly described mineralization process and unique element enrichments raise questions about its broader distribution globally and potential importance to hydrothermal processes, element mass balance, and seabed mineral resources.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"27 8","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026GC012955","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148784344","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":"Developing New Amphibole Thermobarometers to Constrain High P-T Hydration Processes of Basic-Ultrabasic Rocks","authors":"Wenbo Xu,&nbsp;Weilin Chen,&nbsp;Shubham Choudhary,&nbsp;Shijie Li,&nbsp;Jintao Zhu,&nbsp;Xiaogang Ma,&nbsp;Jiamin Wang,&nbsp;Shujuan Jiao,&nbsp;Guibin Zhang,&nbsp;Lifei Zhang,&nbsp;Renbiao Tao","doi":"10.1029/2026GC013146","DOIUrl":"https://doi.org/10.1029/2026GC013146","url":null,"abstract":"<p>Amphibole compositions record high-pressure-temperature (<i>P-T</i>) hydration processes during magmatism and metamorphism in the deep Earth. However, amphibole thermobarometers calibrated for basic–ultrabasic systems are scarce. To address this issue, we compiled Ca-amphibole data from published equilibrium experiments and used machine-learning models to identify temperature- and pressure-sensitive compositional parameters. Guided by these machine-learning-derived insights and subsequent statistical analyses, we developed empirical amphibole barometers based on Al^VI and B-site Na, coupled with whole-rock SiO₂, and internally consistent thermometers based on TiO₂, Al^IV, and A-site cation sum (Sum-A) for basic-ultrabasic rocks. We applied them to amphibole-bearing metamorphic eclogites and metasomatic mantle xenoliths. For example, application to amphiboles in retrograde eclogites from the Thongmön region of the Himalaya consistently captured well-defined paths of ultrahigh-temperature (UHT) metamorphism, corroborating previous estimates derived from thermodynamic phase equilibria modeling and other established thermobarometers (Wang et al., 2021, https://doi.org/10.1016/j.epsl.2021.116760). Furthermore, we successfully constrained the <i>P-T</i> conditions of an igneous basic-ultrabasic xenolith from the Pripyat rift of the East European Craton and peridotite xenoliths from Avacha volcano, Kamchatka. In both cases, the resulting <i>P-T</i> conditions are consistent with the inferred igneous and metasomatic processes in these geological settings. Moreover, the <i>P-T</i> estimates obtained from our amphibole thermobarometers are in strong agreement with those derived from previously established methods for UHT metamorphism and metasomatism, confirming their reliability. Consequently, our calibrated amphibole thermobarometers provide a robust framework for interpreting metamorphic and metasomatic <i>P-T</i> conditions in hydrated basic–ultrabasic systems, which may also be relevant to planetary bodies beyond Earth.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"27 8","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026GC013146","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148783788","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":"Oxygen Isotopic Composition of Miocene Meteoric Water (δ18Ow) in Alpine Foreland Basins","authors":"Armelle Ballian,&nbsp;Maud J. M. Meijers,&nbsp;Daniel Boateng,&nbsp;Isabelle Cojan,&nbsp;Sebastian G. Mutz,&nbsp;Todd A. Ehlers,&nbsp;Andreas Mulch","doi":"10.1029/2025GC012854","DOIUrl":"https://doi.org/10.1029/2025GC012854","url":null,"abstract":"<p>The reconstructed stable oxygen isotopic composition of meteoric water (δ¹⁸O_w) is widely used for paleoclimate reconstructions. Understanding past environmental factors that drove changes in δ¹⁸O_w is essential for interpreting past climate conditions. Here, we investigate the spatial and temporal variations of δ¹⁸O_w in the Miocene Alpine foreland basin from multiple proxy materials with isotope-enabled climate model simulations. Based on δ¹⁸O values and clumped isotope-based temperatures of pedogenic carbonate nodules, we compare Middle Miocene δ¹⁸O_w records from the Northern Alpine Foreland Basin (NAFB) in Switzerland and its counterpart in the Mediterranean Alpine foreland (Digne-Valensole Basin, SE France). Additionally, we analyze isotope-tracking atmospheric general circulation model outputs of δ¹⁸O in precipitation for the Middle Miocene and present-day to assess changes in distributions. Our results highlight a latitudinal δ¹⁸O_w gradient in the Middle Miocene that is similar to the present-day. The occurrence of distinct N-S differences in δ¹⁸O_w values during the Miocene are likely the result of a similar-to-present climate divide (North-Atlantic vs. Mediterranean climates). Concurrently, we suggest that shifts in atmospheric circulation over the Alpine region during certain time intervals of the Middle Miocene led to rapid high-amplitude variations in δ¹⁸O_w. We note significant differences in δ¹⁸O_w values between proxy-based reconstructions and climate model simulations that we attribute to (a) proxy biases toward higher δ¹⁸O_w values and (b) inappropriate model resolution and topography for the Miocene Alpine region. Our study advances the use of multiproxy data-model comparison for paleoclimate and paleoaltimetry reconstructions and points out the importance of integrating proxy and modeling approaches.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"27 8","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GC012854","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148753856","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":"Evolution of Tectonically Accreted Topmost Oceanic Lithospheric Mantle Based on Seismic Tomography Constraints at the Ultraslow-Spreading Southwest Indian Ridge","authors":"A. Corbalán,&nbsp;M. R. Nedimović","doi":"10.1029/2026GC013002","DOIUrl":"https://doi.org/10.1029/2026GC013002","url":null,"abstract":"<p>Oceanic lithosphere formed at the global mid-ocean ridge system makes up &gt;60% of Earth's solid surface. Its uppermost ∼6 km are accreted either magmatically, where mafic melt is available, or tectonically, where this melt is absent. The magmatically accreted lithosphere is known to evolve with age, as demonstrated by its velocity increase. However, whether and how the tectonically accreted lithosphere evolves remains poorly constrained, despite representing about 1/6 of the global seafloor accretion. Here, we provide the first constraints on the evolution of the tectonically accreted topmost lithosphere, composed of exhumed ultramafic rocks, at the ultraslow-spreading Southwest Indian Ridge. The increase in seismic velocities from 0 to 6 Ma is ∼62% greater than in the topmost 6 km of magmatically accreted lithosphere, with most of this increase occurring at greater depths (1.5–4.5 km). Progressive serpentinization with aging of the topmost ∼2 km reduces velocities, partially counteracting the increase caused by crack closure and pore infilling. Thus, the overall alteration of the tectonically accreted lithosphere is likely greater than indicated by the velocity increase alone, implying that it evolves more rapidly than its magmatic counterpart. Our water content estimates further suggest that the upper 6 km of tectonically accreted topmost lithosphere can store up to three times more water than equivalent magmatically accreted lithosphere. This enhanced water storage may promote increased arc magmatism and intraslab seismicity at future subduction zones, when the Arctic, Atlantic and Indian Ocean basins begin to close, and tectonically formed lithosphere is recycled back into the Earth.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"27 8","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026GC013002","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148753592","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":"Vanadium Isotopic Compositions of the High-3He/4He Baffin Island Lavas","authors":"Jonas Kaare-Rasmussen,&nbsp;Forrest Horton,&nbsp;Maureen Auro,&nbsp;Andy W. Heard,&nbsp;Sune G. Nielsen","doi":"10.1029/2025GC012861","DOIUrl":"https://doi.org/10.1029/2025GC012861","url":null,"abstract":"<p>The isotopic composition of vanadium (V) in hotspot lavas provides new insight into the source of deep mantle heterogeneities. We measured V isotopic compositions in Paleogene Baffin Island lavas, which erupted above the Iceland plume head, to constrain the mantle plume source. These lavas have V isotopic compositions that are lighter (−0.96 ± 0.02‰, 2 s.e., <i>n</i> = 25) than most other mantle-derived lavas (δ⁵¹V = −0.89 ± 0.02, 2 s.e., <i>n</i> = 69). This difference is statistically significant with a 99.8% confidence interval. The measured ⁵¹V/⁵⁰V ratio in Baffin Island is difficult to reconcile with the assimilation of continental crust, fractional crystallization, crystal accumulation, isotopic fractionation during mantle melting, or the recycling of sediments. Possibly, the Baffin Island lavas sample an ancient (&gt;3 Ga) melt-depleted mantle reservoir. However, this cannot explain the similarly low ⁵¹V/⁵⁰V measured in younger lavas related to the Iceland plume. Instead, the V isotopic composition of Baffin Island lavas may be consistent with the incorporation of core-affected material into the Iceland plume. The advection of bulk core into the lowermost mantle is improbable, so we hypothesize that, if the V isotopic difference is due to core-mantle interactions, V partitioned into core-exsolved oxides that imparted a core-like V isotopic composition on the Baffin Island mantle source.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"27 8","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GC012861","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148753391","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":"Structurally-Controlled Permeability Evolution and Mineralization in Geothermal Caprocks: The Fenice Capanne Mining District (Southern Tuscany, Italy)","authors":"Barbara Marchesini,&nbsp;Federico Rossetti,&nbsp;Ahmad Rabiee,&nbsp;Andrea Billi,&nbsp;Andrea Cavallo,&nbsp;Davide Novella,&nbsp;Vincenzo Moretto,&nbsp;Antonio Caracausi,&nbsp;Fabio Trippetta,&nbsp;Luca Aldega,&nbsp;Luigi Dallai,&nbsp;Giovanni Ruggieri,&nbsp;Eugenio Carminati","doi":"10.1029/2026GC012944","DOIUrl":"https://doi.org/10.1029/2026GC012944","url":null,"abstract":"<p>The Neogene mineralized region of the Colline Metallifere in southern Tuscany (Italy) provides a natural laboratory to investigate feedback between fluid–rock interaction, structurally controlled fluid flow, and hydrothermal ore mineralization. This study focuses on the Fe–Cu–Pb–Zn deposit of Fenice Capanne, located south of the active Larderello–Travale geothermal system, where marly–limestone caprocks of the Liguride Complex preserve evidence of permeability creation and destruction above a regional geothermal reservoir. A multidisciplinary approach was applied to reconstruct the evolution of the hydrothermal system. Two main alteration stages were identified. An early prograde, high-temperature skarn metasomatism was associated with the growth of clinopyroxene–garnet assemblages and characterized by substantial gains in Si, Fe, Mn, and Ca, resulting in a large volume increase (up to ∼400%). Reaction-induced fracturing generated secondary permeability, which superimposed on primary permeability related to bedding and lithological anisotropies, enhancing hydraulic connectivity. A subsequent retrograde stage, below ∼300°C, was driven by mixing between meteoric and saline magmatic-derived fluids, or those derived from evaporite interaction, and resulted in renewed fracturing, brecciation, and extensive quartz–sulphide veining. These processes recorded cyclic variations in fluid composition, redox conditions, salinity, and boiling associated with transient pressure drops during hydraulic fracturing. Overall, the Ligurian marly–limestone sequence evolved from a low-permeability sedimentary seal into a reactive mineralized system capable of sustaining transient hydrothermal circulation. Structural connectivity controlled by faulting and reaction-induced fracturing governed both permeability evolution and mineralization. These results demonstrate that sedimentary caprocks can behave as dynamic components of the hydrothermal systems, with important implications for geothermal fluid flow, metal transport, and reservoir evolution.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"27 8","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026GC012944","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148753392","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":"An Open-Source Markov Chain Monte Carlo Inversion Software for the Analysis of Experimental Rock Deformation Data","authors":"C. Jain,&nbsp;J. Korenaga","doi":"10.1029/2026GC013065","DOIUrl":"https://doi.org/10.1029/2026GC013065","url":null,"abstract":"<p>Despite its importance in modeling the interior dynamics of a planet, our understanding of interior rheology remains incomplete because of several reasons, including insufficient experimental data and inadequate analysis of the available data. To address the latter, Korenaga and Karato (2008, https://doi.org/10.1029/2007jb005100) developed a new and statistically robust approach to analyze experimental data on the plastic deformation of mineral assemblages, and its functionality has since been expanded. It is based on Bayesian statistics and is implemented by a Markov chain Monte Carlo (MCMC) method with Gibbs sampling. It is designed to explain the experimentally observed strain rates with a more realistic but highly nonlinear rheological model—the composite rheological model—which accounts for the simultaneous operation of multiple creep mechanisms. Our software, named <span>labmc</span>, can efficiently handle the inversion of experimental data for such complex rheologies. Moreover, it incorporates a thorough treatment of data uncertainties, which yields more robust estimates on the flow-law parameters for the assumed rheological model. In this paper, we describe the <span>labmc</span> software and provide representative examples to explain how the software is used and the MCMC inversion results analyzed to obtain meaningful constraints on rock rheologies.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"27 8","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026GC013065","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148753139","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":"Distinct Transcrustal Evolutions of Komatiitic Primitive Magma: Implications for the Compositional Dichotomy of Continental Flood Basalts","authors":"Zongpeng Yang,&nbsp;Tong Hou,&nbsp;Roman Botcharnikov,&nbsp;Evangelos Moulas,&nbsp;Meng Wang,&nbsp;Stephan Buhre,&nbsp;Zhaochong Zhang","doi":"10.1029/2026GC013187","DOIUrl":"https://doi.org/10.1029/2026GC013187","url":null,"abstract":"<p>The origin of the compositional dichotomy between high-Ti and low-Ti basalts in continental flood basalt provinces remains debated. Most existing studies attribute this dichotomy directly to variations in primitive magma composition to circumvent the complexities of significant evolutionary processes, such as multiphase fractional crystallization. Here, we evaluate komatiite as a viable parental magma for the late Permian Emeishan Large Igneous Province to constrain its magmatic evolution. Olivine phenocrysts and spinel inclusions in the investigated picrites exhibit close affinities, consistent with derivation from a common komatiitic parental magma. Thermobarometric constraints define an olivine-spinel-clinopyroxene crystallization sequence and reveal two pressure regimes: 0–4.4 and 5.7–8.5 kbar. Thermodynamic modeling successfully reproduces the observed mineral assemblages and liquid lines of descent, accounting for two distinct adiabatic and multi-stage evolutionary paths. We propose that extensive crustal differentiation along the liquid line of descent produced high-Ti basalts, whereas limited evolution, melt-cumulate re-equilibrium, or incomplete crystal-melt segregation generated low-Ti basalts. These results demonstrate that contrasting crustal evolutionary pathways acting on a common komatiitic magma govern compositional diversities observed in global continental flood basalt provinces.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"27 8","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026GC013187","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148753035","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}