Contributions to Mineralogy and Petrology最新文献

{"title":"Hybrid granite factory in the continental lower crust: an accessory mineral perspective from the Ivrea-Verbano Zone, Northern Italy","authors":"Caliméria do Carmo,&nbsp;Oscar Laurent,&nbsp;Olivier Vanderhaeghe,&nbsp;Andrea Galli,&nbsp;Lorenzo Tavazzani,&nbsp;Emilie Bruand","doi":"10.1007/s00410-026-02325-w","DOIUrl":"10.1007/s00410-026-02325-w","url":null,"abstract":"<div><p>Granitoids and volcanic rocks of hybrid composition between mantle and crustal components are common in various tectonic settings and contribute to both the growth and differentiation of the continental crust. However, the mechanisms by which such hybrid magmas are produced are debated. We focus on a key lower crustal exposure of the Permian Sesia Magmatic System located in the Ivrea-Verbano Zone—IVZ, Italy, allowing to directly investigate the deep roots of a hybrid magmatic system. Integrating multi-scale field observations and bulk-rock data with zircon and apatite petrochronology (U–Pb dating, trace elements, Lu–Hf and Sm–Nd isotopes respectively), we show that lower-crustal orthopyroxene-bearing rocks associated to migmatites in a ‘frozen’ hybridization zone, correspond to hybrid cumulates from which melts were extracted to form upper crustal granitic plutons. Igneous zircon records at least three crystallization stages: (i) initial low-crystallinity hybridization phase at lower-crustal scale; (ii) subsequent chemical differentiation in a mush system, driven by reactive porous flow at the 10²–10³ m scale; and (iii) final crystallization after significant melt extraction and subsequent, smaller-scale (10⁰–10⁻¹ m) chemical equilibration. Apatite, on the other hand, is fully homogenized at the sample scale but chemical differences between samples preserve the first-order hybridization trends. While crustal-scale differentiation (melt extraction, transfer and cooling) took place in a short time span (ca. 2–4 Ma) as previously suggested in the IVZ, our zircon U–Pb data are permissive of the construction and equilibration of the lower crustal system over a longer period of ca. 15 Myr minimum. Our study also reveals the potential of accessory minerals, in particular zircon, to preserve the successive steps involved in the complex history of the lower crust, even at high temperatures.</p></div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"181 6","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147829182","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phase equilibria and liquid lines of descent in alkali basalts at one atmosphere and the role of oxygen fugacity","authors":"Sophia Y. M. Thorn,&nbsp;Olivier Namur,&nbsp;David A. Neave,&nbsp;Bernard Charlier,&nbsp;Jasper Berndt,&nbsp;Stephan Klemme","doi":"10.1007/s00410-026-02309-w","DOIUrl":"10.1007/s00410-026-02309-w","url":null,"abstract":"&lt;div&gt;&lt;p&gt;This study presents new experimental data on the effect of oxygen fugacity (&lt;i&gt;f&lt;/i&gt;O&lt;sub&gt;2&lt;/sub&gt;) and bulk composition on phase equilibria and liquid lines of descent in alkali basalts. Crystallisation experiments were performed at one atmosphere, in the temperature range 1220–1050 °C and at fO&lt;sub&gt;2&lt;/sub&gt; conditions corresponding to fayalite–magnetite–quartz (FMQ) equilibrium and the following log-unit deviations from this equilibrium: FMQ-1, FMQ + 1.5 and FMQ + 3. Experiments were grouped into two series, those on primitive compositions (9.9–11.9 wt% MgO; total alkali 3.1–5.3 wt%), and those on evolved compositions (5.1–5.8 wt% MgO; total alkali 5.7–8.6 wt%). Experiments on primitive compositions produce assemblages of olivine, clinopyroxene and spinel, with plagioclase present in less silica-undersaturated compositions. Experiments on evolved compositions produce similar assemblages, though olivine is often absent at higher fO&lt;sub&gt;2&lt;/sub&gt;. Whitlockite is present at low temperature, plus occasional Fe-Ti oxides. Nepheline is only observed in the most silica-undersaturated composition at low temperature. Mineral compositions and stability are strongly controlled by bulk composition and redox conditions. High MgO bulk contents favour the early appearance of olivine, while the appearance of clinopyroxene is dictated by both MgO and CaO contents. Increasing silica-undersaturation produces assemblages dominated by clinopyroxene and a high melt fraction at any given temperature, promoting alkali enrichment during melt evolution. Oxidising conditions enhance the crystallisation of spinel and other Fe-Ti oxides, in which both silica and alkalis are incompatible, through increased melt Fe&lt;sup&gt;3+&lt;/sup&gt;/ΣFe. This promotes more modest enrichments in Na&lt;sub&gt;2&lt;/sub&gt;O and K&lt;sub&gt;2&lt;/sub&gt;O with respect to SiO&lt;sub&gt;2&lt;/sub&gt; as crystallisation proceeds, with the effect strongest where bulk concentrations of FeO&lt;sub&gt;tot&lt;/sub&gt; are high and P&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5&lt;/sub&gt; are low. It follows that &lt;i&gt;f&lt;/i&gt;O&lt;sub&gt;2&lt;/sub&gt; exerts a stronger control over the liquid lines of descent of more primitive liquids than evolved ones. We combine our results with those from the literature to calibrate new models for both &lt;span&gt;({K}_{{{rm D}}_{{{rm Fe}}^{2+}-text{Mg}}}^{{rm Ol}-{rm Melt}})&lt;/span&gt; and &lt;span&gt;({K}_{{{rm D}}_{{{rm Fe}}^{T}-text{Mg}}}^{{rm Ol}-{rm Melt}})&lt;/span&gt; in alkaline systems, with the latter formulated as:&lt;/p&gt;&lt;div&gt;&lt;div&gt;&lt;span&gt;$${K}_{{{rm D}}_{{{rm Fe}}^{T}-text{Mg}}}^{{rm Ol}-{rm Melt}}(pm 0.012, text{a.a.d.})=0.442 left(pm 0.029right)+0.287 left(pm 0.035right)left[{text{X}}_{{text{SiO}}_{2}}right]-0.442left(pm 0.027right)left[frac{{text{X}}_{{text{Na}}_{2}text{O}}+{text{X}}_{{{rm K}}_{2}text{O}}}{{text{X}}_{{text{SiO}}_{2}}}right]- 0.168left(pm 0.022right)left[{text{X}}_{text{Fo}}right]-0.138(pm 0.008)frac{1}{(1-left[frac{{text{Fe}}^{3+}}{Sigma text{Fe}}right])}$$&lt;/span&gt;&lt;/div&gt;&lt;/div&gt;&lt;p&gt;where &lt;span&gt;({text{X}}_{i})&lt;/span&gt; is the mole fraction of &lt;span&gt;(i)&lt;/span&gt; in ","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"181 6","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147808200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Calibration of the Fe–Ir redox sensor at high pressure and the oxygen fugacity of laser heated diamond anvil cell experiments","authors":"S. Dominijanni,&nbsp;D. J. Frost,&nbsp;L. S. Dubrovinsky,&nbsp;N. Miyajima,&nbsp;E. Koemets,&nbsp;G. Aprilis,&nbsp;S. Chariton,&nbsp;T. Fedotenko,&nbsp;S. Khandarkhaeva,&nbsp;C. Melai,&nbsp;I. Koemets,&nbsp;Z. Liu,&nbsp;V. Cerantola,&nbsp;A. Chumakov,&nbsp;M. Hanfland,&nbsp;V. Svitlyk,&nbsp;A. D. Rosa,&nbsp;C. A. McCammon","doi":"10.1007/s00410-026-02314-z","DOIUrl":"10.1007/s00410-026-02314-z","url":null,"abstract":"<div>\u0000 \u0000 <p>The Fe–Ir binary alloy has been calibrated up to 100 GPa as a part of a thermodynamic model (oxygen fugacity <span>({(f}_{{text{O}}_{2}}))</span> sensor system) to monitor the redox conditions during high–pressure and high–temperature petrology experiments. The existing Fe–Ir activity–composition relations at 1 bar and ~ 473–2873 K have been updated by including the pressure dependence on the activity–composition relations. We calibrated the volume dependent interaction parameter <span>({W}^{V})</span> up to 61 GPa and extrapolated the Margules activity model (i.e., <span>({W}_{text{Fe}-text{Ir}}^{G})</span> and <span>({W}_{text{Ir}-text{Fe}}^{G})</span>) up to 100 GPa by combining the experimentally determined compressibility and compositional data of the alloy, with those of the end member phases in a thermodynamic model. We apply the newly calibrated redox sensor to oxygen fugacity determination during laser heated diamond anvil cell (LHDAC) experiments. In situ LHDAC experiments were performed up to ~ 61 GPa and ~ 2000 K. We tracked the <span>({f}_{{text{O}}_{2}})</span> conditions in the DAC by reacting the powdered mixture during laser heating to form a Fe–Ir alloy (sliding redox sensor) and using high–resolution synchrotron Mössbauer Source spectroscopy, powder X–ray diffraction, X–ray absorption near–edge structure spectroscopy, analytical transmission electron microscopy, and chemical analyses down to the nanoscale. The inferred oxygen fugacities measured at the specific <i>P–T</i> conditions of the experiments are ~ 1 log unit below the iron–wüstite buffer, which is lower than estimates obtained with the existing model and compared to multi anvil experiments performed with the same starting mixture at similar<i> P–T</i> conditions.</p>\u0000 </div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"181 5","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00410-026-02314-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147796655","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-bearing nodules from Tenerife reveal magma reservoir diversity prior to caldera-forming eruptions","authors":"Emma L Horn,&nbsp;Rex N Taylor,&nbsp;Thomas M Gernon,&nbsp;Michael J Stock,&nbsp;Katherine E Schofield,&nbsp;Richard J. Brown,&nbsp;Victoria C Smith,&nbsp;Danielle McLean","doi":"10.1007/s00410-026-02302-3","DOIUrl":"10.1007/s00410-026-02302-3","url":null,"abstract":"<div>\u0000 \u0000 <p>Partially crystalline nodules are occasionally discovered within breccias linked to large ignimbrite-forming eruptions, providing evidence of the fragmentation of the plutonic reservoir and conduit system during such eruptions. These nodules offer valuable insights into the magmatic systems fuelling these highly explosive volcanoes. On Tenerife, crystal-rich samples containing interstitial melt are preserved in several Plinian eruption deposits spanning over ~ 1.8 million years, but the crustal architecture and interactions between magma reservoirs beneath the island remain poorly understood. This study focuses on explosively fragmented juvenile nodules from Tenerife’s pyroclastic deposits, which provide snapshots of the mush reservoir preceding caldera-forming events. Petrological, major element and trace element analyses were conducted on juvenile nodules from five major caldera-forming eruptions: Caleta (221 ka), Fasnia (312 ka), San Juan (1.50 Ma), Morteros (~ 1.70 Ma), and Gaviotas (1.84 Ma). These nodules preserve a range of crystallisation stages within Tenerife’s alkaline magmatic system, uniquely containing interstitial groundmass that existed in a supra-solidus state at the time of eruption, with an average melt content of ~ 25 vol%. Despite macro-mineralogical variability between eruptions, the juvenile nodules exhibit consistent basanite interstitial groundmass chemistry and lithologies, suggest that the mafic mush reservoir beneath Tenerife has remained both chemically and petrologically stable over ~ 1.8 million years. This study provides a new perspective on the stability of the mafic mush reservoir beneath Tenerife, highlighting its persistent role in the volcano’s magmatic plumbing system. The chemical consistency of the mush contrasts with the episodic mobilisation and more chemically diverse evolved phonolite melts, underscoring the importance of understanding mid-crustal processes leading to explosive eruptions. These findings provide evidence for a long-lived, stable mush reservoir and a new perspective on the compositional makeup of the crystal-mush reservoirs at defined points in time, enhancing our temporal understanding of ocean island volcanoes and their crustal magma mush reservoirs.</p>\u0000 </div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"181 5","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13121400/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147759152","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":"Zoned feldspar records hydration-dehydration cycles in lower-crustal shear zones","authors":"Kristina G. Dunkel,&nbsp;Sascha Zertani,&nbsp;Vladimir Roddatis,&nbsp;Bjørn Jamtveit","doi":"10.1007/s00410-026-02317-w","DOIUrl":"10.1007/s00410-026-02317-w","url":null,"abstract":"<div><p>Metamorphic reactions provide crucial insights into the conditions that rocks experienced and significantly influence their rheological behaviour. However, some reactions are challenging to identify in the rock record. This study focuses on zonation and microstructures in plagioclase as indicators of metamorphic history, employing a case study from Lofoten, northern Norway, where various types of plagioclase microstructures are preserved together. We use a combination of electron microscopy techniques (electron backscatter diffraction, transmission electron microscopy, and electron microprobe analyses) complemented with local equilibrium thermodynamic modelling to examine the relationships between composition, microstructures, and underlying metamorphic processes, and put that in context with previous observations of metamorphically zoned plagioclase, often referred to as “complex feldspar”. Needle-shaped Ca-richer zones in plagioclase represent pseudomorphs after zoisite/clinozoisite, indicative of plagioclase breakdown following fluid infiltration at high pressure and subsequent reversal of the reaction. Polygonal plagioclase with complex zonations also originates from the hydration/dehydration cycle but has additionally undergone deformation during hydration. Minor changes in pressure and temperature at upper amphibolite-facies conditions can significantly affect the stability and microstructures of plagioclase and thereby the rheological behaviour of the lower crust.</p></div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"181 5","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00410-026-02317-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147738697","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":"Experimental insights into phase relations and liquid lines of descent of low- and high-Si boninitic magmas from the Izu-Bonin-Mariana fore-arc","authors":"Lennart Koch,&nbsp;Renat R. Almeev,&nbsp;Felix Marxer,&nbsp;François Holtz","doi":"10.1007/s00410-026-02312-1","DOIUrl":"10.1007/s00410-026-02312-1","url":null,"abstract":"<div>\u0000 \u0000 <p>Hydrous equilibrium crystallization experiments were conducted on two boninitic melt compositions, low-Si boninite (LSB) and high-Si boninite (HSB), from the Izu-Bonin-Mariana (IBM) fore-arc to constrain the evolution of magma storage conditions and differentiation during subduction initiation. Experiments were performed at temperatures between 1020 and 1220 °C and at pressures of 200 and 400 MPa. Additionally, 14 natural boninite samples were analyzed for direct comparison. The experiments show that boninitic magmas crystallize orthopyroxene and/or olivine (± Cr-spinel) along the liquidus followed by clinopyroxene and finally plagioclase. Magmatic H₂O suppresses plagioclase formation and stabilizes olivine and clinopyroxene relative to orthopyroxene. Residual melts follow calc-alkaline trends, evolving to high-Mg andesitic and (high-Mg) dacitic compositions. Experimental results indicate that IBM boninitic magmas were strongly hydrous. Water contents of 1–3 wt% are estimated for LSB magmas and 3–5 wt% for HSB magmas. These different H₂O contents confirm the increasing importance of water fluxes during the evolution of boninitic magmas, from LSB in early stages to HSB in later stages. In contrast, systematic differences in magma storage conditions could not be detected. LSBs and HSBs both differentiated at temperatures between 1220 and 1040 °C and were stored at pressures between 100 and 300 MPa prior to eruption. Our study demonstrates that residual boninitic melt evolution was controlled by (near-)equilibrium crystallization processes. However, the contributions of additional magmatic processes including magma mixing and reworking of harzburgitic/dunitic cumulates during early stages of subduction initiation result in the large compositional variety observed for Izu-Bonin-Mariana fore-arc eruptive products.</p>\u0000 </div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"181 5","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00410-026-02312-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147738611","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":"Elusive isotopic signatures of recharge and assimilation in the arc-adjacent silicic volcanic systems of the Loicas Trough, Argentina","authors":"Marie Katrine Traun,&nbsp;N. Søager,&nbsp;T. E. Waight,&nbsp;P. Waterton,&nbsp;C. Münker,&nbsp;R. Andreasen,&nbsp;S. B. Iannelli","doi":"10.1007/s00410-026-02319-8","DOIUrl":"10.1007/s00410-026-02319-8","url":null,"abstract":"<div>\u0000 \u0000 <p>Open system processes including recharge and assimilation are fundamental drivers of volcanic activity and can provide the trigger for major eruptions. We explore these open system processes in silicic volcanic centres of the Loicas Trough, an arc-adjacent volcanic province, situated between the Andean main and back arc in the Southern Volcanic Zone Argentina. We model the effect of open system processes on bulk radiogenic Pb, Nd, Hf, Sr isotopes and in situ major element and ⁸⁷Sr/⁸⁶Sr compositions of plagioclase crystals, using Magma Chamber Simulator (MCS). Our results and MCS models reveal the amount of assimilation and crustal heterogeneity overwhelm potential source variations, and assimilation trends are largely controlled by residual wallrock mineralogy. Plagioclase phenocrysts indicate several disequilibrium events, including recharge as seen from zonation, resorption and sieve textures and An% profiles. In situ Sr isotope measurements displayed limited intra-crystal variation. MCS models of bulk compositions and plagioclase zonation reveal that recharge events are generally elusive in bulk rock and mineral isotopic data. The compositional impact of recharge is smaller than the natural variation of the data trends, despite clear textural evidence for recharge events. This has important implications for using geochemical proxies to identify open system magma chamber processes and eruption trigger mechanisms in silicic volcanic centres.</p>\u0000 </div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"181 5","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147738265","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hydrogen isotope fractionation in olivine-hosted melt inclusions during passive degassing, CO2 flushing, and magma ascent","authors":"Ayla S. Pamukçu,&nbsp;Glenn A. Gaetani","doi":"10.1007/s00410-026-02310-3","DOIUrl":"10.1007/s00410-026-02310-3","url":null,"abstract":"<div>\u0000 \u0000 <p>Suites of mineral-hosted melt inclusions commonly display variability in their H₂O and CO₂ concentrations that are challenging to explain by a single process. Recent work has shown that H₂O can diffuse rapidly through olivine, allowing olivine-hosted melt inclusions to diffusively equilibrate with an external melt that has a different H₂O concentration. This process can cause the concentrations of H₂O, and in many cases CO₂, in melt inclusions to deviate from isobars and degassing paths. Diffusion of H⁺ through the olivine lattice can fractionate deuterium (²H or D) from hydrogen, and here we use a discretized diffusive equilibration model to investigate the D⁺/H⁺ fractionation associated with passive degassing, CO₂ flushing, and magma ascent – three processes that affect the concentration of H₂O in the external melt and thereby induce diffusive H₂O exchange – on H₂O and D⁺/H⁺ in olivine-hosted melt inclusions. Our model results show that these three processes lead to distinctly different trends in the H₂O concentration and D⁺/H⁺ signature of a melt inclusion. However, the timescale of a given process will impact whether the hallmarks of that process are preserved in natural inclusions. While our models focus on olivine-hosted melt inclusions and basanitic melt compositions, the conceptual framework and effects of these processes should apply to any melt inclusion-host crystal system that can be affected by diffusive exchange of hydrogen. Capturing these signatures in datasets is possible, particularly in the case of magma ascent, but it requires high-precision H₂O and D⁺/H⁺ analyses in a melt inclusion suite that has a wide range of inclusion sizes. </p>\u0000 </div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"181 5","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147714813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microstructures of amphibole clusters in mafic magmatic enclaves of the Early Cretaceous Sanguliu granitic pluton in East China: insights for chaotic magma mixing processes in a hybrid boundary layer","authors":"Zisong Zhao,&nbsp;Christina Yan Wang,&nbsp;Wei Tan","doi":"10.1007/s00410-026-02307-y","DOIUrl":"10.1007/s00410-026-02307-y","url":null,"abstract":"<div>\u0000 \u0000 <p>Amphibole clusters commonly occur in mafic magmatic enclaves (MMEs) and their aggregation mechanisms provide insights into physical processes of magma mixing. This study uses electron backscatter diffraction (EBSD) to examine the formation of amphibole clusters in MMEs from the Sanguliu monzogranitic pluton in East China. The amphibole clusters appear as loose to dense aggregates and range in size from 2 to 5 mm. EBSD results reveal that approximately 40% of neighboring-paired grains exhibit preferred orientation with inter-grain misorientation angle of &lt; 5° or 180°, driven by interfacial energy minimization. This indicates aggregation via synneusis, i.e., suspending grains collide, then rotate to minimize interfacial energy and sinter. Intra-grain misorientation (&gt; 5° up to 12°) and kinked boundaries are attributed to plastic and brittle deformation induced by crystal crowding. Individual grains range in length from ∼0.1 to 0.5 mm and show bright and dark domains in BSE images. The bright and dark domains have distinct Al/Si ratios, similar to amphibole in the diabase dyke intruding the pluton and in host monzogranite, respectively, indicating crystallization from both mafic and felsic magmas. The amphibole clusters are thus interpreted to form in a hybrid boundary layer between ascending mafic mushy magmas and overlying felsic mushy magmas in the shallow crust. A Rayleigh number of ~ 9.4 × 10⁷ implies chaotic convection within the layer, facilitating amphibole movement, impingement, rotation and aggregation. This study demonstrates that crystallographic and chemical records of amphibole clusters in MMEs bear insightful information for chaotic mushy magma mixing in a hybrid boundary layer.</p>\u0000 </div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"181 5","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147714814","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Apatite geochronology of the Sept-Iles Intrusive Suite (Grenville province, Canada) reveals two magmatic episodes 55 Myrs apart related to plume arrival and subsequent rifting","authors":"Hélène Legros,&nbsp;Marie A. Kieffer,&nbsp;Sarah A. S. Dare,&nbsp;Olivier Namur,&nbsp;Michael D. Higgins,&nbsp;Dany Savard,&nbsp;Stijn Glorie","doi":"10.1007/s00410-026-02320-1","DOIUrl":"10.1007/s00410-026-02320-1","url":null,"abstract":"<div>\u0000 \u0000 <p>The Sept-Iles Intrusive Suite, Quebec, Canada, comprises several components, including the third largest mafic layered intrusion in the world. Until now, the age of the whole suite was estimated at 565 ± 4 Ma based on zircon U-Pb dating from a single sample. However, the Layered Series component consists of three Mega Cyclic Units (MCU) which may record distinct magmatic events. This study uses apatite and zircon U-Pb and Lu-Hf geochronology to constrain the emplacement age of samples from the top of MCU I and II. Apatite from MCU I yields U-Pb dates of ca. 620 Ma. Samples from MCU II, stratigraphically above MCU I, yield a homogeneous U-Pb apatite date of ca. 565 Ma, overlapping the Lu-Hf apatite date of 567 ± 14 Ma, and the U-Pb zircon crystallization age of 564 ± 2 Ma. Based on these new ages and geochemical signatures, we propose a revised nomenclature for the Layered Series of the Sept-Iles Intrusive Suite. The ca. 620 Ma unit is divided into the Rivière Sainte-Marguerite unit (RSM; former MCU I) and Rivière des Rapides unit (RdR; former MCU III), the high (Gd/Yb)_N ratios in RSM cumulus apatite indicating partial melting at depth related to the Central Iapetus Magmatic Province mantle plume. The Lac au Castor unit (LC; former MCU II) was injected as a sill at ca. 565 Ma, with lower (Gd/Yb)_N ratios in cumulus apatite reflecting decompression melting of shallow asthenospheric mantle during subsequent rifting and opening of the Iapetus Ocean some 55 Myrs later.</p>\u0000 </div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"181 4","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147643041","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}