Contributions to Mineralogy and Petrology最新文献

{"title":"Mineral inclusions in rims of large Gahcho Kué diamonds (Northern Canada): how was magnesiochromite trapped?","authors":"Gary Fung,&nbsp;Maya G. Kopylova,&nbsp;Ekaterina S. Kiseeva,&nbsp;Benjamin King","doi":"10.1007/s00410-026-02375-0","DOIUrl":"10.1007/s00410-026-02375-0","url":null,"abstract":"<div><p>We studied diamonds from the Gahcho Kué kimberlite (Northern Canada) using a new chemical-cleaning protocol applied to laser-cut offcuts of large diamonds (&gt; 3 cts; ~10–15 mm in size). Primary diamond inclusions (DIs) preserved in the rims of the large diamonds comprise magnesiochromite, olivine, sulfide, omphacite, garnet, and enstatite. Thirty-two diamonds (84%) are classified as peridotitic, three (8%) as eclogitic, and three (8%) as websteritic, yielding a paragenetic distribution consistent with that of smaller diamonds from the same locality. Nitrogen and hydrogen characteristics are likewise comparable between large and small diamonds, indicating that both belong to a single population. Magnesiochromite inclusions in the rims of large diamonds record equilibration temperatures of 1060 ± 50 °C, corresponding to pressures of approximately 46–61 kbar along the fitted Gahcho Kué geotherm of 37–38 mW/m². Relative to the smaller diamonds, the rims of large diamonds exhibit lower proportions of nitrogen in B centres and magnesiochromite inclusions with lower Mg# (~ 62 vs. 67), consistent with a core-to-rim cooling trend of approximately 70 °C. These observations suggest continuous diamond growth during progressive cooling. At Gahcho Kué, as at numerous diamond localities worldwide, magnesiochromite inclusions are markedly overrepresented relative to the modal abundance of magnesiochromite in peridotite, and this overrepresentation is even more pronounced in larger diamonds. This “magnesiochromite enigma” may relate to preferential resorption of peridotite silicates and/or preferential nucleation of diamond on magnesiochromite (if protogenetic), or co-precipitation of diamond and magnesiochromite during progressive cooling (if syngenetic).</p></div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"181 12","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149367323","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":"Pitfalls in metamorphic phase equilibria modelling caused by phase-in reaction kinetics: insights from overstepping the staurolite-forming reaction","authors":"Zhen M. G. Li,&nbsp;Fred Gaidies,&nbsp;Yi-Chao Chen,&nbsp;Feng Guo,&nbsp;Chun-Ming Wu","doi":"10.1007/s00410-026-02376-z","DOIUrl":"10.1007/s00410-026-02376-z","url":null,"abstract":"<div><p>Equilibrium thermodynamic modelling is commonly used to simulate garnet chemical zoning and reconstruct metamorphic pressure–temperature (<i>P–T</i>) histories, but the reaction kinetic effects may be overlooked. We integrate petrography, garnet chemical zoning, and thermodynamic calculations for metapelitic samples from the garnet and staurolite zones of Longmenshan (SW China) to examine the effects of delayed progress of the staurolite-forming reaction. In the staurolite-free garnet‑zone sample, suppressing staurolite yields a better fit to the chemical zoning and size of the largest garnet, whereas the staurolite-involved model predicts staurolite and fits poorly near the rim. In staurolite‑zone sample 20SC37, garnet records two growth segments: Grt 1 formed before staurolite and Grt 2 after staurolite, as revealed by two textural relationships: Grt 2 is absent on staurolite-contacting faces but preserved on matrix-facing faces, and staurolite inclusions only occur in Grt 2. The staurolite-involved model terminates Grt 1 growth at a smaller size than observed, whereas the staurolite-suppressed model better reproduces Grt 1 zoning and size. The initial low-Ca composition of Grt 2 cannot be reproduced from the Grt 1-fractionated bulk composition, indicating a change in effective reactive composition after staurolite formation. An adjacent staurolite-zone sample 20SC42 preserves the same Grt 1–staurolite–Grt 2 textural relation, and isopleths for the core composition of its largest garnet crystal already intersect in a staurolite-bearing equilibrium field. Conventional thermobarometry yields <i>P–T</i> conditions consistent with the phase equilibrium and garnet growth modelling. These results support overstepping of the staurolite-forming reaction and show that a calculated phase-in boundary should not be treated automatically as the point where the natural reaction proceeded. This highlights the kinetic effect of a later phase-in reaction on an already growing garnet population during metamorphism.</p></div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"181 12","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149367324","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":"From partial melting to pluton emplacement: insights from zircon and titanite petrochronology of the El Oro complex, Ecuador","authors":"Hugo Dominguez,&nbsp;Renée Tamblyn,&nbsp;Mahyra Tedeschi,&nbsp;Nicolas Riel,&nbsp;Jacob B. Forshaw,&nbsp;Etienne Jaillard,&nbsp;Samuel Macías-Mosquera,&nbsp;Pierre Lanari","doi":"10.1007/s00410-026-02346-5","DOIUrl":"10.1007/s00410-026-02346-5","url":null,"abstract":"<div><p>Partial melting of the lower continental crust during high-temperature, low-pressure metamorphism is commonly associated with the emplacement of felsic plutons in the middle to upper crust. However, the duration and conditions of anatexis, melt extraction, and emplacement processes in these settings remain uncertain. The El Oro Complex in southern Ecuador preserves a kilometre-scale, tilted crustal section comprising a structurally continuous Triassic sequence of metamorphosed sedimentary rocks and associated S-type granitoids. A large number per sample of combined in situ zircon U–Pb dates and trace-element compositions has been obtained by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) from both migmatites in the lower paleo-crust and granitoids in the middle to upper paleo-crust. This approach, combined with cathodoluminescence imaging, is used to distinguish different zircon populations within individual samples beyond U–Pb analytical uncertainty. All samples from both migmatites and granitoids mostly record zircon crystallisation ages between ca. 240 and 225 Ma. In the migmatites, trace-element heterogeneity in zircon is observed at the sample scale. Depending on the sample, this variability reflects either changes in the melting reactions or open-system behaviour involving melt influx from other sources at the scale of individual leucosomes. U–Pb dates and Zr-thermometry data from titanites using LA-ICP-MS were also collected from the Piedras metagabbro, commonly interpreted as the heat source for the sequence’s metamorphism. Titanite grains record a consistent age of 227.5 ± 4.5 (<i>n</i> = 94) Ma with a temperature of ~ 720–740 °C, and are interpreted as dating the cooling of the gabbro emplacement related to the end of metamorphism. Together, these data confirm the co-genetic link between the migmatites and the granitoids of the El Oro complex and the interpretation that the Piedras unit is the main heat source for the metamorphism. This study showcases important trace-element variability in zircons at the sample scale, both in migmatites and granitoids, reflecting the interplay between partial melting, melt extraction, and subsequent crystallisation.</p></div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"181 11","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00410-026-02346-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149338297","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":"Stability of SiC polytypes at mantle conditions: constraints on the origin of natural moissanite","authors":"Kenta Kobayashi,&nbsp;Ryosuke Sinmyo,&nbsp;Takayuki Ishii,&nbsp;Shuhou Maitani","doi":"10.1007/s00410-026-02373-2","DOIUrl":"10.1007/s00410-026-02373-2","url":null,"abstract":"<div><p>Although silicon carbide (SiC, moissanite) is rarely found in geological samples, it may provide essential insights into the global volatile cycle and redox state of the deep Earth. The stability of SiC polytypes under high-pressure conditions has large potential for understanding the structure and dynamics of the interior of the Earth and planets. However, the stability of the polytypes remains poorly constrained, as the strong kinetic barrier hinders precise determination of their stability at high temperatures and pressures. Here, we studied the stability of 6H- and 3C-SiC under deep-Earth and planetary conditions using a Kawai-type multi-anvil apparatus and examined the kinetics of the phase transition at 5 – 20 GPa and 1500 – 2500 K over 1 – 4320 minutes. We determined the phase abundances as a function of heating duration under high-pressure conditions. Although the transformation kinetics were very sluggish, we clearly observed the phase transition from 6H- to 3C-SiC at 5 – 20 GPa and 2000 – 2500K, achieving high transformation ratios of up to 70 % after 60 minutes of heating. In contrast, the transformation ratio was nearly 0 % at 1500 K and 15 – 20 GPa, regardless of heating duration up to 4320 minutes. We re-determined the stability of SiC polytypes, reconciling all plausible previous results by taking heating duration into account. Current results show that 6H-SiC is stable over a broader range of pressure and temperature than previously reported. This is consistent with the dominant 6H polytype population in natural SiC, contrary to prior knowledge indicating a wide stability pressure-temperature range of 3C-SiC. Rarely found 3C-SiC may originate from a deep subducted slab at least above approximately 20 GPa. This imposes a fundamental constraint on the formation of natural SiC and suggests that SiC polytypes can serve as indicators not only of redox conditions but also of formation depth.</p></div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"181 11","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00410-026-02373-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149339360","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":"Petrogenesis of boninite-like high-Mg lavas and mafic rocks from the Xigaze ophiolites, southern Tibet: implications for magma-poor oceanic crustal accretion","authors":"Hong-Yu Li,&nbsp;Chuan-Zhou Liu,&nbsp;Tong Liu,&nbsp;Yong-Qiang Hu,&nbsp;Jia-Ning Zhu,&nbsp;Chang Zhang","doi":"10.1007/s00410-026-02374-1","DOIUrl":"10.1007/s00410-026-02374-1","url":null,"abstract":"<div><p>The Yarlung-Tsangpo ophiolites (YTO) preserve discontinuous oceanic crustal sections in which volcanic and intrusive rocks are locally associated with serpentinized mantle peridotites. Here we report field and petrographic observations, whole-rock geochemistry, mineral geochemistry, and Sr–Nd-Hf isotopic data for boninite-like high-Mg lavas and mafic rocks from the Deji ophiolite in the central YTO, southern Tibet. Most lavas in the Deji volcanic sequence have N-MORB-like compositions, whereas the boninite-like high-Mg lavas appear to form a subordinate component. These high-Mg lavas have relatively high MgO and SiO₂, low TiO₂, high Cr and Ni contents, and depleted incompatible element abundances. However, they contain abundant clinopyroxene phenocrysts and lack olivine and orthopyroxene phenocrysts, and are therefore referred to as boninite-like high Mg lavas rather than true boninites. Andesitic diabase sills intrude the volcanic sequence and have trace element characteristics with N-MORB affinity. Olivine gabbronorites preserve poikilitic textures and hydrous mineral assemblages, whereas mantle-hosted gabbroic veins record clinopyroxene-dominated crystallization and variable hydrothermal overprinting. Clinopyroxene equilibrium melts calculated from the volcanic and intrusive rocks show broadly N-MORB REE patterns, although those of the boninite-like high-Mg lavas have lower REE abundances. Whole-rock Nd-Hf isotopes indicate broadly similar depleted mantle sources, whereas variable Sr isotopes mainly reflect fluid-related overprinting. We interpret the Deji crustal rocks as products of an evolving magma-poor oceanic magmatic system dominated by N-MORB-like melts, with local generation of more depleted boninite-like high-Mg melts. In our preferred model, hydrothermal fluid infiltration along detachment-related faults hydrated the shallow mantle. Later asthenospheric upwelling and mafic melt input promoted localized deserpentinization, fluid release, and limited hydrous melting of refractory harzburgite. This process may have produced small volumes of boninite-like high-Mg melts without requiring the whole volcanic sequence to be boninitic. The Deji ophiolite thus provides a useful case study of coupled magmatic, tectonic, and hydrothermal processes during magma-poor oceanic crustal accretion.</p></div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"181 11","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149338670","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":"Magma recharge and mixing in the decades leading up to three andesitic VEI 3–5 eruptions (Misti volcano, Peru)","authors":"Marie K. Takach,&nbsp;Frank J. Tepley III,&nbsp;Jordan Lubbers,&nbsp;Christopher J. Harpel,&nbsp;Rigoberto Aguilar,&nbsp;Marco Rivera","doi":"10.1007/s00410-026-02372-3","DOIUrl":"10.1007/s00410-026-02372-3","url":null,"abstract":"<div><p>Misti volcano in southern Peru is an active composite cone &lt; 18 km away from the country’s second largest city, Arequipa (population &gt; 1.1 million). Recent studies detail the volcano’s tephrostratigraphy, physical volcanology, and petrology during the Pacheco stage (≤ 21–2 ka) to better understand future signs of volcanic unrest and activity. Here, we apply Mg, Sr, and Ba diffusion chronometry to plagioclase in pumice from three tephra-fall deposits emplaced by Pacheco stage eruptions to estimate recharge-to-eruption timescales. Modeled chemical gradients identified in plagioclase zones near crystal rims in all three deposits are interpreted to have formed via magma recharge and mixing, which also provided the final impetus for eruption to occur. Tephra-fall deposits were selected to represent the range of inferred pre-eruptive processes during this stage, including melt homogenization between mixing magmas that is complete (magma hybridization, Autopista deposit) and incomplete (magma mingling, La Rosada and Ponche Iridescente deposits). Modeled Mg, Sr, and Ba timescales range from 2 h to 268 years (La Rosada; <i>n</i> = 80), 48 h to 201 years (Ponche Iridescente; <i>n</i> = 39), and 6 h to 327 years (Autopista; <i>n</i> = 54). Only 6% of all timescales are &gt; 100 years and &lt; 2% are &lt; 1 day. Thus, 94% of all diffusion timescales for these processes, regardless of pre-eruptive scenario and modeled element, are on the scale of a human lifetime. We also demonstrate the difficulty of modeling Mg and Ba diffusion in plagioclase at Misti due to complications in selecting initial conditions. We therefore prefer to further refine the full timescale ranges using only Sr, as it is the most reliably modeled element. Excluding outliers, Sr timescales range from 2 h to 94 years (La Rosada; <i>n</i> = 41), 54 h to 25 years (Ponche Iridescente; <i>n</i> = 26), and 3 months to 50 years (Autopista; <i>n</i> = 24). The retrieved timescales for magma recharge and mixing processes taking place in the middle to upper crust fit well within the tephra-fall eruption occurrence intervals of &lt; 2000–5000 years. The longer eruption occurrence intervals may reflect the tempo of magma making its way from the mantle source through the crust, while the diffusion timescale only captures the final magmatic event. If future episodes of magma recharge are detected in the middle to upper crust beneath Misti, diffusion timescales reported herein may help to inform eruption forecasting and mitigate hazards to nearby inhabitants of the region.</p></div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"181 11","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149338744","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":"Shallow magma storage and degassing at Brothers volcano, Kermadec arc: implications for submarine hydrothermal processes and seafloor mineralisation","authors":"Shane M. Rooyakkers,&nbsp;Ery C. Hughes,&nbsp;Cornel E. J. de Ronde,&nbsp;Frank J. Tepley III,&nbsp;Michael C. Rowe,&nbsp;Penny E. Wieser,&nbsp;Ariadni Georgatou,&nbsp;Philipp A. Brandl,&nbsp;Christian Timm,&nbsp;Isabelle Chambefort","doi":"10.1007/s00410-026-02371-4","DOIUrl":"10.1007/s00410-026-02371-4","url":null,"abstract":"<div><p>Magmas degas volatiles and metals into submarine arc-related hydrothermal systems, but the nature of this process and its role in seafloor massive sulfide (SMS) mineralisation are poorly understood, particularly in submarine arcs hosting Cu–Au-rich deposits. To address this, we studied glassy melt inclusions (MIs) and matrix glasses from Brothers submarine volcano in the Kermadec arc, where there is strong evidence for magmatic involvement in hydrothermal processes and Cu-Au-rich mineralisation. We present a new dataset of volatile contents (H₂O, CO₂, S, Cl), sulfur speciation, and trace element concentrations for these materials, including samples recovered from IODP drill cores. Primitive basaltic MIs from a nearby mafic ridge imply that the volatile contents and <i>fO</i>_<i>2</i> (~ FMQ + 1.5) of parental Brothers melts are within the normal range for arc magmas, but they contain high concentrations of some chalcophile metals (notably, Cu). Silicic (dacite/low-SiO₂ rhyolite) MIs from the main Brothers edifice record degassing of an S-bearing vapour phase under oxidising conditions (<i>fO</i>_<i>2</i> ~FMQ + 2) at very shallow depths (~ 1–3 km below seafloor). These vapours are Cl- and metal-poor, but trigger acid sulfate alteration and likely provide a dilute source of trace metalloids, plus some Au and Cu. The Cl contents (max = 6480 μg g⁻¹) of silicic Brothers MIs are among the highest known for any subalkaline arc magmas. Increasing Cl contents with differentiation indicate a progressive approach to brine saturation, inferred to be reached only at late stages of crystallisation when the magma is no longer eruptible. Such late, shallow degassing of Cl is traditionally viewed as unfavourable for metal extraction, contrasting with deeper and earlier degassing in subaerial porphyry systems. The unusually high Cu and Au grades of Brothers SMS mineralisation, however, imply that significant quantities of metal are mobilised into the hydrothermal system. We suggest that the adverse effects of late Cl degassing on metal extraction at Brothers are offset by (1) very shallow magma storage, providing circulating hydrothermal fluids direct access to dense metal-rich brines and magmatic sulfides, and (2) elevated metal contents in primitive parental Brothers melts, which enhance the overall magmatic metal budget. The Brothers example suggests that these factors may be more important controls on Cu–Au‑rich mineralisation in submarine arcs than in subaerial arcs built on thicker crust, where more favourable degassing regimes can develop. Ultimately, Brothers demonstrates that arc-related SMS-forming systems can be strongly magmatically influenced and share both commonalities and differences with Cu-Au mineralised subaerial systems.</p></div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"181 11","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00410-026-02371-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149234493","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":"Olivine-hosted melt inclusions provide insights into primitive magma compositions driving young eruptions from Red Crater, Tongariro (New Zealand)","authors":"Kerstin Gruender,&nbsp;Simon J. Barker,&nbsp;Michael C. Rowe,&nbsp;Chris E. Conway","doi":"10.1007/s00410-026-02368-z","DOIUrl":"10.1007/s00410-026-02368-z","url":null,"abstract":"<div><p>Volcanism at continental arcs is ultimately driven by mantle-derived magmas; however, erupted compositions are typically overprinted by crustal interactions during ascent, obscuring deeper signatures. We target olivine and their melt inclusions (MI) in basaltic andesite scoria erupted from Red Crater (Tongariro, New Zealand) to capture primitive melt compositions prior to upper crustal processing. Olivine crystals comprise several, mostly antecrystic populations, with forsterite contents from Fo_70–91 and variable textures indicative of complex crystallisation histories within a dynamic, transcrustal magmatic system. MI in forsteritic (≥ Fo₈₄) olivine cores contain primitive basaltic melts and record early fractionation (~10–20%) of olivine, spinel ± clinopyroxene at sulfur-saturated, moderately oxidised conditions during entrapment. Incompatible trace elements display variable enrichments in fluid-mobile and light rare earth elements that can be explained by ~3–10% partial melting of a shallow mantle source with variable contributions of slab-derived fluid and/or sediment components and minor to no crustal assimilation. Similarities with caldera-associated olivine-hosted MI in the central Taupō Volcanic Zone (TVZ) suggest a common source, with differences such as higher calcium and chlorine at Red Crater and trace element variations potentially related to distinct slab-derived contributions, differences in mantle mineralogy, degree of melting or crustal interactions. Offsets in incompatible trace element abundances between Red Crater olivine-hosted MI, groundmass glass and whole-rock compositions imply 10–20% crustal contamination with metasedimentary basement rocks during magma ascent and shallow storage. Whole-rock data are considered less suitable for investigating primitive magma compositions and mantle sources, with olivine-hosted MI providing a more robust basis for interpretations.</p></div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"181 11","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00410-026-02368-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149189272","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":"Variable zircon, titanite and apatite response during magma hybridization and autometasomatism","authors":"Guillermo A. Ortiz-Joya,&nbsp;Roberto F. Weinberg,&nbsp;Marcos Morfulis,&nbsp;Lucas Eduardo de Abreu Barbosa Araujo,&nbsp;Alfonso Sola,&nbsp;Ivan Belousov,&nbsp;Jeffrey Oalmann","doi":"10.1007/s00410-026-02365-2","DOIUrl":"10.1007/s00410-026-02365-2","url":null,"abstract":"<div><p>The U–Pb records of accessory minerals can become difficult to interpret when magmatic crystallization is overprinted by hydrothermal alteration and element redistribution. The Archibarca Pluton, in the shallow portion on the Paleozoic Famatinian Arc in northwestern Argentina, preserves a complex history of magma crystallization, magma mixing (hybridization), and autometasomatism that variably overprints the textures, chemistry and U–Pb record of zircon, titanite and apatite. We found that hydrothermal modification affects zircon U–Pb dates and trace element compositions, producing complex and apparently concordant date distributions. Nevertheless, after filtering analyses affected by metasomatic modification, zircon retains geochronological information that is consistent with the magmatic and hydrothermal history recorded by titanite and apatite. Thus zircon can preserve useful chronological information even in hydrothermally modified systems, but its U–Pb record should be evaluated together with textural and geochemical evidence and complemented by other accessory mineral petrochronometers to distinguish magmatic crystallization from subsequent fluid-mediated changes. Zircon displays a spectrum of preserved and modified domains, in which chemical alteration, expressed as Fe–Ti–P–Y-LREE enrichment or depletion, may be either coupled or decoupled from U–Pb dates. Although zircon yields apparently concordant LA–ICP–MS dates spanning from ~ 500 to 420 Ma, these dates should be interpreted with caution, as metasomatic modification can disturb the U–Pb system without producing evident chemical alteration. Therefore, trace-element-based filtering is insufficient to discriminate disturbed zircon dates. A SHRIMP date of 441 ± 5 Ma (MSWD = 0.5) obtained from a composite magmatic-metasomatic zircon overlaps with its LA–ICP–MS date (445 ± 1 Ma, MSWD = 11); however, the latter exhibits substantial excess scatter, indicating that part of the date dispersion reflects analytical sensitivity to disturbed domains rather than geological complexity alone. In contrast, titanite preserves a more robust magmatic U–Pb record, with most samples yielding consistent crystallization dates of ~ 460 to 450 Ma, overprinted by fluid-related Pb loss at ~ 420 to 390 Ma. Additional complexities include inheritance at ~ 611 Ma and partial Permian (~ 280 Ma) resetting linked to regional Choiyoi magmatism. Titanite exhibits dual petrochronological behaviour, recording both magmatic dates and hydrothermal overprint, whereas magmatic and hydrothermal apatite yield indistinguishable U–Pb dates (439 ± 13 Ma and 436 ± 13 Ma), interpreted to record cooling of the pluton below ~ 450 °C. In summary, integrating the textural, chemical and isotopic data from these three accessory phases help constrain the nature and timing of the magmatic-hydrothermal transition in plutonic rocks.</p></div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"181 11","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00410-026-02365-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149125683","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":"Deformation, metamorphism, and time: a multi-method approach to mid-low temperature geochronology in Precambrian cratons","authors":"Laura Nania,&nbsp;Jeremy William Powell,&nbsp;Duane C. Petts,&nbsp;Dawn Kellett,&nbsp;Daniele Regis,&nbsp;Alfredo Camacho,&nbsp;Brandon Boucher,&nbsp;Riccardo Graziani,&nbsp;Janina Czas,&nbsp;Matthew Polivchuk,&nbsp;Marc Beauchamp","doi":"10.1007/s00410-026-02344-7","DOIUrl":"10.1007/s00410-026-02344-7","url":null,"abstract":"<div><p>This study examines the microstructural, petrological, and geochemical processes that disrupt date relationships within biotite and apatite. We combine SEM-EBSD, cold/SEM-cathodoluminescence, EPMA and LA-ICP-MS geochemical mapping, with in situ multi-system geochronology (⁴⁰Ar/³⁹Ar and ⁸⁷Rb–⁸⁷Sr in biotite, apatite U–Pb) to investigate grain-scale microstructural controls on isotopic systematics in rocks from the south Rae craton, Canada. Our results show that intracrystalline defects (subgrains, kink bands, twin planes) and intercrystalline decompression-related fabrics (strain-softened and fluid-prone domains) promote fluid-mediated redistribution of major and trace elements (e.g., Rb, Sr, Ar, U, Th, Pb, La, Ce) in biotite and apatite, enabling recrystallization and/or open system behaviour. This results in both older and younger ⁸⁷Rb–⁸⁷Sr dates relative to ⁴⁰Ar/³⁹Ar and U–Pb systems within the same samples, independently of tectonic domain, reflecting spatially variable isotopic resetting, inheritance, and recycling. These findings underscore how age distributions in biotite and apatite are controlled by spatially variable recrystallization, inheritance, and fluid-mediated reworking rather than simple cooling through closure temperatures. ⁴⁰Ar/³⁹Ar, ⁸⁷Rb–⁸⁷Sr and U–Pb systems are best interpreted in terms of grain-scale processes rather than cooling paths. Regionally, our youngest 1.73–1.76 Ga ages reflect a late overprint and intracratonic reworking, suggesting that apparent cooling trends in the Trans-Hudson Orogen may sometimes record isotopic disturbance rather than exhumation. Integration of microstructural and geochemical mapping with micro-spatially resolved geochronology provides a more robust framework for interpreting legacy datasets and guiding in situ isotopic dating.</p></div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"181 10","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00410-026-02344-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149132082","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}