Contributions to Mineralogy and Petrology最新文献

{"title":"Correction to: Buoyancy-driven propagation of an isolated fluid-filled crack in rock: implication for fluid transport in metamorphism","authors":"Kui Han, Xinzhuan Guo, Hanyong Liu, Fengbao Ji","doi":"10.1007/s00410-025-02199-4","DOIUrl":"10.1007/s00410-025-02199-4","url":null,"abstract":"","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"180 2","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143107950","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":"Remobilization of century-old magmas during the 2018 basaltic caldera-forming eruption at Kīlauea Volcano (Hawai‘i)","authors":"Adrien J. Mourey,&nbsp;Euan J. F. Mutch,&nbsp;Thomas Shea","doi":"10.1007/s00410-025-02204-w","DOIUrl":"10.1007/s00410-025-02204-w","url":null,"abstract":"<div><p>The recent eruptions at Kīlauea Volcano (Hawai‘i) raised some fundamental questions on the longevity and the preservation of eruptible magma batches left over from previous eruptions. Fingerprinting magma batches at Kīlauea through time with bulk and glass compositions is challenging. Narrow compositional changes (e.g., Nb/Y ratio) in matrix glasses occur over time because of repeated magma mixing, and residence timescales of stored evolved magmas in the lower East Rift Zone are underconstrained. To evaluate the diversity in composition and the minimum residence timescales in Rift Zone magmas, we analyzed major and trace elements in plagioclase and matrix glasses from selected samples that erupted in the first weeks of the 2018 Kīlauea eruption. Plagioclase crystals in these samples represent mixed populations with a range in composition spanning An_30-80, corresponding to rhyodacitic to basaltic compositions and temperatures from 950 to 1200 °C. Diffusion modeling of Mg in these plagioclase crystals indicate minimum crystal residence timescales that range from &lt; 1 to ~ 480 years. The complex zoning patterns in plagioclase (and resorptions) together with the protracted storage timescales from diffusion modeling imply that magmas from the East Rift Zone accumulated various plagioclase populations recording magma mixing events that occurred a few years to a few centuries before the 2018 eruption. The diversity of the magma batches (observed with An-Mg compositions in plagioclase) erupted in a single eruption offers research pathways to potentially estimate the frequency, volume and eruptibility of these evolved magmas, thereby refining the risk in the region.</p></div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"180 2","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143109871","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":"The spinel to garnet phase transition in the systems MgO-Al2O3-SiO2 and CaO-MgO-Al2O3-SiO2: new experiments to resolve long-standing discrepancies","authors":"Nicholas Farmer,&nbsp;Hugh St. C. O’Neill,&nbsp;Eleanor C. R. Green","doi":"10.1007/s00410-025-02203-x","DOIUrl":"10.1007/s00410-025-02203-x","url":null,"abstract":"<div><p>The pressure and temperature conditions of the transition from spinel to garnet as the stable aluminous phase in peridotite lithologies of the upper mantle is integral to elucidating the tectonic significance of the ‘garnet signature’ in basalts. It provides an essential constraint on models of mantle partial melting and oceanic crust formation. Existing experimental results on the univariant phase transition in the simple systems MgO-Al₂O₃-SiO₂ (MAS) and CaO-MgO-Al₂O₃-SiO₂ (CMAS) are mutually inconsistent. To resolve this, we have re-determined the <i>P-T</i> coordinates of the univariant transition in both synthetic systems by running experiments containing both systems simultaneously in the piston-cylinder apparatus, along with the MgO-ZnO pressure sensor. These experiments show a ~ 0.4 GPa difference in the pressure of the spinel/garnet phase transition between the two chemical systems at 1400 ºC, double that inferred from a compilation of existing experimental data. Absolute pressure in these experiments can be verified using the MgO-ZnO sensor. The results imply that the thermodynamic data used in recent mineral equations of state based on the Holland-Powell thermodynamic dataset are substantially correct.</p></div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"180 2","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00410-025-02203-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143110177","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":"A grain boundary model of garnet growth","authors":"Frank S. Spear","doi":"10.1007/s00410-025-02201-z","DOIUrl":"10.1007/s00410-025-02201-z","url":null,"abstract":"<div><p>Numerical models for the growth of garnet are presented to evaluate the relative significance of reaction-limited growth and diffusion-limited growth following garnet nucleation after significant overstepping of the equilibrium garnet-in reaction. Reactions are only permitted among phases that are adjacent across grain boundaries and the extent of reaction at a given reaction site is scaled to the local amount of chemical affinity available to the two or three reactant phases relative to the grain boundary composition. This local affinity is dissipated as the local reaction proceeds, which changes the composition of the adjacent grain boundary “phase” and sets up chemical gradients that drive diffusion along the grain boundaries. Reactions proceed until all affinity is exhausted at which point the rock is essentially at equilibrium. Two extremes are modeled. Reaction-limited growth is modeled as infinitely rapid grain boundary diffusion whereas diffusion-limited growth is modeled by assuming that reactions proceed infinitely fast such that the supply of nutrients and removal of waste products from a reaction site is restricted by the rate of diffusion. Models are presented with model assemblages chlorite + quartz + garnet and chlorite + quartz + muscovite + biotite + plagioclase + garnet. Reaction-limited models result in garnets displaying well-formed “bell-shaped” Mn zoning profiles with all garnet crystals showing similar amounts of growth and zoning profiles. Diffusion-limited models result in mineral growth or consumption that is texture-sensitive such that the amount of consumption or production of a phase depends on the location of the crystal in the sample and the proximity of other phases. For example, the total amount of garnet continues to increase for the duration of diffusion-limited models although locally an individual garnet crystal may first grow and then be consumed. Mn zoning in models with short diffusion times display distinct “peaks” in the central garnet cores, in contrast to the bell-shaped profiles in reaction-limited models. With increasing diffusion times, these Mn zoning profiles evolve towards bell-shapes. These models demonstrate that diffusion-limited growth of garnet porphyroblasts may result in textural and compositional complexities that are not encapsulated by bulk-rock thermodynamic modeling.</p></div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"180 2","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00410-025-02201-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142995641","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":"Crust‐mantle decoupling in the Gakkel Ridge induced by strong heterogeneity of the asthenosphere","authors":"Yang Xu,&nbsp;Chuan-Zhou Liu,&nbsp;Yin-Zheng Lin,&nbsp;Bo-Da Liu","doi":"10.1007/s00410-025-02198-5","DOIUrl":"10.1007/s00410-025-02198-5","url":null,"abstract":"<div><p>Abyssal peridotites can provide complementary information on the compositional features of the asthenosphere, as the refractory mantle within the asthenosphere contributes little to the genesis of mid-ocean ridge basalts (MORB). Here we present major and trace elements of ~ 70 abyssal peridotites from the Sparsely Magmatic Zone (SMZ) and Eastern Volcanic Zone (EVZ) of the Gakkel Ridge, which are residues of the asthenosphere that have undergone &lt; 15% partial melting. Their clinopyroxenes display LREE-depleted and LREE-flat patterns, the latter of which resulted from refertilization by quasi-instantaneous melts in the melting zone beneath the mid-ocean ridge. Compositions of the Gakkel peridotites are highly variable along the ridge axis, which cannot be attributed to the spatial variation of temperature of the asthenosphere. The estimated degrees of melting of the Gakkel abyssal peridotites are higher than the values inferred by seismic thickness of ocean crust along the SMZ and EVZ. This implies the Gakkel abyssal peridotites inherit ancient melting prior to their entering the Gakkel Ridge, which also causes the crust-mantle decoupling in compositions. Moreover, compositions of the Gakkel peridotites differs significantly from subduction-related peridotites. We suggest the asthenosphere beneath the Gakkel Ridge is highly heterogeneous in compositions, which is the culprit of crust-mantle geochemical decoupling. Enriched MORB erupted in the SMZ region were derived from small amounts of enriched components within the asthenosphere, which cannot be represented by the abyssal peridotites exposed in this region.</p></div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"180 2","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142995582","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":"Quantifying the partial melting of Himalayan Metamorphic core in Eastern Himalaya: implications for crustal rheology","authors":"Purbajyoti Phukon,&nbsp;Md. Sunny Hussain,&nbsp;Takeshi Imayama,&nbsp;Jia-Min Wang,&nbsp;Kazumasa Aoki,&nbsp;Sanjeeb Behera","doi":"10.1007/s00410-025-02200-0","DOIUrl":"10.1007/s00410-025-02200-0","url":null,"abstract":"<div><p>The Himalayan orogeny caused partial melting of rocks within the Greater Himalayan Sequence (GHS), forming migmatites. The extensive occurrence of such migmatites in the lower structural level of the GHS (GHS_L) is a distinctive feature of the Western Arunachal Himalaya (WAH), situated in eastern part of the orogen; meanwhile leucogranite is predominantly found in the highest reaches of the GHS_L. A comprehensive multi-method study incorporating field observations, petrography, phase equilibrium modelling, geochemical analysis, and zircon U–Pb and monazite U–Th–Pb geochronology was conducted on migmatitic paragneiss and leucogranites from the GHS_L along the Bomdila-Tawang section of the WAH. P–T pseudosection modelling reveals a clockwise P–T path characterized by prograde burial and heating, significant melt production, and nearly isothermal decompression during melt solidification. Structural observations, including concordant and discordant relationships between leucosomes and gneissic bands, suggest that deformation established pathways for melt migration. Zircon U–Pb dates reveal bimodal protolith ages of ~ 1350 Ma (Ectasian) and ~ 900 Ma (Tonian). Insufficient zircon overgrowth (&lt; 20 μm), likely due to extensive melt extraction during suprasolidus metamorphism, precludes younger age determination. Monazite U-Th-Pb age indicates peak metamorphism of the GHS_L at ca. 25–26 Ma, synchronous with MCT initiation in the WAH. Melt generation at peak metamorphic conditions in the GHS_L reached ~ 16 vol% in stromatic metatexites and ~ 26 vol% in layered diatexites and of these generated melts, &gt; 50% escaped at depths of ~ 30–34 km. This extensive migration formed complex leucosome networks, contributing to regional leucogranite distribution and rheological weakening, enabling ductile flow within the GHS.</p></div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"180 2","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142976653","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":"Early Permian post-collisional magmatism induced by extensive removal of the Variscan lithospheric mantle","authors":"Andrea Boscaini,&nbsp;Joshua H. F. L. Davies,&nbsp;Morgann G. Perrot,&nbsp;Raffaele Sassi,&nbsp;Claudio Mazzoli,&nbsp;Angelo De Min,&nbsp;Corrado Morelli,&nbsp;Evelyn Kustatscher,&nbsp;Thomas Blanchet-Gavouyère,&nbsp;Andrea Marzoli","doi":"10.1007/s00410-024-02196-z","DOIUrl":"10.1007/s00410-024-02196-z","url":null,"abstract":"<div><p>The tectonic re-equilibration after the Variscan orogeny coincided with widespread early Permian post-collisional magmatism in southern Europe. A full understanding of the origin of this magmatism in the South Variscan realm and its relationship to major tectonic events such as subduction, continental collision, rifting or lithospheric foundering hinges on high-precision geochronological data of the magmatic products. Here, we present new high-precision zircon U–Pb geochronological data obtained by chemical abrasion isotope dilution thermal ionization mass spectrometry (CA-ID-TIMS) for the early Permian Athesian Magmatic District (AMD) in NE Italy. Our analysed zircons from felsic intrusive and volcanic rocks give ages spanning from ca. 281.8 to 277.2 Ma, suggesting that the lifetime of the AMD was significantly shorter than previously reported. Our data, when combined with recent high-precision ages from other South Variscan magmatic systems suggest that the Cisuralian (early Permian) post-collisional magmatism in the Southalpine domain occurred over more than 8 m.y. with the magmatic centres migrating from the western to the eastern Southern Alps. Geochemical and radiogenic isotope modelling of published data for magmatic rocks in the Southern Alps and the Corsica-Sardinia batholith suggest a subduction-enriched mantle source for the South Variscan post-collisional magmatism, with melting occurring under a relatively thin lithosphere at depths of ca. 60 km. Our results point to a significant post-orogenic delamination of the thick lithospheric mantle formed during the Variscan orogeny. In this scenario, the migration of the post-collisional magmatism within the Cisuralian district may be due to the lateral migration of the lithospheric foundering.</p></div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"180 2","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142939112","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":"Water solubility of olivine under redox-controlled deep upper mantle conditions: effects of pressure, temperature and coexisting fluids and implications","authors":"Kai Zhang,&nbsp;Li Li,&nbsp;Charles R. Stern,&nbsp;Xiaozhi Yang","doi":"10.1007/s00410-024-02197-y","DOIUrl":"10.1007/s00410-024-02197-y","url":null,"abstract":"<div><p>Water as structural hydroxyl in olivine plays an important role in determining the water budget of the upper mantle and its numerous physicochemical properties. However, the solubility of water in olivine in the deep upper mantle (i.e., 300–410 km depth), which defines the maximum water content under given conditions, still needs to be known with high precision. We examined the water solubility by annealing experiments under conditions controlled by Fe-FeO buffer and peridotite assemblages at 10–13 GPa and 1100–1450 ºC, using a starting olivine of representative chemistry and different fluid materials. The experimental conditions were broadly consistent with those prevailing in the deep upper mantle. The attainment of equilibrium water incorporation in the H-annealed olivine samples was ensured by H diffusion kinetics, water profile analyses and time-series studies. The annealed samples demonstrate infrared hydroxyl bands at 3650–3000 cm⁻¹, but the relative band patterns are different from those observed in the available H-annealing experiments at 1–7 GPa under otherwise comparable conditions (including starting materials). The obtained solubility of water increases with increasing both temperature and pressure over the run conditions, and differs apparently between the runs equilibrated by different fluids that are relevant to the deep upper mantle and water solubility studies. In general, the water solubility of olivine increases nonlinearly with increasing depth in the upper mantle, and can be described as: <i>C</i>_w = (290 ± 78) × exp ((0.0043 ± 0.0006) × depth (km))– (268 ± 89) (H₂O as coexisting fluid) and <i>C</i>_w = (149 ± 72) × exp ((0.0046 ± 0.0011) × depth (km))–(132 ± 85) (CH₄-H₂O as coexisting fluid), where <i>C</i>_w is water solubility (ppm wt. H₂O). The water solubility of olivine in the realistic upper mantle should be defined from the runs coexisting with CH₄-H₂O, and the highest value is only ~ 800 ± 80 ppm wt. H₂O, implying that the actual water contents of olivine in the upper mantle must be mostly (if not exclusively) lower. The inferred storage capacity of water in peridotite in the upper mantle reaches its maximum of 600 ± 100 ppm wt. H₂O (95% confidence level) at the bottom boundary of ~ 410 km depth, and a minimum of 350 ± 50 ppm wt. H₂O (95% confidence level) is expected at mid-depths of 190–230 km. During the upwelling of relatively water-rich materials from the source regions of enriched mid-ocean ridge basalts or ocean island basalts, hydrous melting would be much easier to trigger at the mid-depths of the upper mantle. The data further suggest that, to produce a pervasive hydrous melting at the ~ 410 km depth, the prevailing water content of the mantle transition zone should be greater than ~ 600 ppm wt. H₂O.</p></div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"180 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142912825","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":"Cooling rates and melt extraction timescales determined by diffusion chronometry on shallow crustal plutonic rocks.","authors":"Thomas Grocolas, Othmar Müntener, Elias M Bloch, Stéphane Escrig, Alexey Ulyanov, Anne-Sophie Bouvier","doi":"10.1007/s00410-025-02238-0","DOIUrl":"10.1007/s00410-025-02238-0","url":null,"abstract":"<p><p>Diffusion chronometry has emerged as a valuable tool to track the timescales of magmatic processes and is now routinely applied on erupted volcanic products to infer crystal residence times and mixing-to-eruption timescales. Despite some attempts to apply such a technique to plutonic rocks, slow cooling in these systems complicates the interpretation of the retrieved timescales. Here we investigate the cooling rates and crystal-melt segregation timescales in the Western Adamello and Re di Castello units of the Adamello batholith (Italy). The Western Adamello is mainly composed of tonalite and volumetrically minor cumulative gabbro and leucotonalite, and segregated granite. The studied area from the Re di Castello exhibits a concentric structure mainly composed of tonalite, granodiorite, and aplitic and pegmatitic granite. Strongly zoned plagioclase crystals occur in both leucotonalite and granodiorite samples, while quartz crystals displaying normal Ti zoning are only observed in some granodiorites. After determining the crystallisation temperatures of plagioclase mantle and rim and quartz, as well as the initial conditions prior to diffusion, cooling rates were estimated based on plagioclase mantle-to-rim and quartz profiles. The retrieved cooling paths correspond, within uncertainty, to cooling rates calculated using thermal modelling and obtained by previous studies using ³⁹Ar/⁴⁰Ar dating. Crystal-melt segregation timescales were then calculated based on the diffusion modelling of plagioclase core-to-mantle profiles and the retrieved cooling rates. The calculated timescales (~ 10⁴-10⁵ yr) likely correspond to the plagioclase core-to-mantle residence time before crystallisation of the rim. Interestingly, these crystal residence times are similar to the zircon crystallisation timespan recorded in the Western Adamello and Re di Castello units, and to the crystal residence times obtained on historical volcanic eruptions (~ 10⁴-10⁶ yr). Overall, these findings highlight that plutonic systems can be used to reconstruct magmatic timescales and support the hypothesis of a close connection between plutonism and volcanism.</p><p><strong>Supplementary information: </strong>The online version contains supplementary material available at 10.1007/s00410-025-02238-0.</p>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"180 8","pages":"45"},"PeriodicalIF":3.5,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12254178/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144625118","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":"Reconstructing mantle–crust boundary magmatism through Cimmerian orogenic events: evidence from deep crustal cumulates in northeastern Pamir","authors":"Masumeh Sargazi,&nbsp;Chuan-Lin Zhang,&nbsp;Yan Jing,&nbsp;Zahid Hussain,&nbsp;Zhi-Hao Song,&nbsp;Hong-Ran Wang,&nbsp;Xiao-Qiang Liu,&nbsp;Xian-Tao Ye","doi":"10.1007/s00410-024-02192-3","DOIUrl":"10.1007/s00410-024-02192-3","url":null,"abstract":"<div><p>Deep crustal cumulates directly represent the geochemical composition of the lower crust and can provide insights into magmatism at the mantle–crust boundary. However, the scarcity of exposed deep crustal cumulates, which is due to their high density causing such rocks to sink into the mantle, limits our access to deep crustal samples. This study investigated hydrous late Mesozoic mafic–ultramafic cumulate rocks from northeastern Pamir. These rocks are the first of their kind identified in this region and exhibit features typical of deep sub-arc hydrous cumulates worldwide. Petrography, zircon U–Pb ages and zircon Lu–Hf isotopes, whole-rock geochemistry and Sr–Nd isotopes, and mineral major and trace element chemistry were used to constrain the magmatic evolution from source to surface and the crystallization conditions of the primary magma at depth. In situ zircon U–Pb dating yielded a concordant age of 199 ± 1.3 Ma. The mafic cumulates are hornblende gabbros, which had a crystallization sequence of amphibole/magnetite → plagioclase → biotite → apatite. Hornblende geobarometry yielded an equilibrium pressure of 0.65–0.80 ± 0.14 GPa, corresponding to depths of 20–26 km. The ultramafic cumulates, are lherzolites and olivine clinopyroxenites that have a crystallization sequence of olivine/spinel → clinopyroxene → ± orthopyroxene. The estimated pressure, based on published experimental constrains, suggests high-pressure crystallization occurred at ~ 1 GPa. The elevated magmatic oxygen fugacity (ƒO₂) is consistent with values expected for sub-arc conditions, where FMQ is 1–4 log units more oxidized than mid-ocean ridge basalts. The trace element composition of melts calculated to be in equilibrium with clinopyroxene is comparable to the global average composition of continental calc-alkaline basalts. Based on the petrography, mineral chemistry, and uniform whole-rock Sr–Nd isotopic data, the mafic–ultramafic cumulate rocks are inferred to have formed by fractional crystallization of a common hydrous (~ 2 wt% H₂O) parental melt derived from a depleted mantle source (⁸⁷Sr/⁸⁶Sr = 0.7046–0.7132 ε_Nd(t) = 1.5–3.3, ε_Hf(t) = 1.1–11). These results support the notion that the polybaric differentiation in the lower crust can significantly influence the diversity of geochemical composition in the upper crust and highlight that the final closure of the Paleo-Tethys in the northeastern Pamir may not have occurred before the early Jurassic.</p></div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"180 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142875287","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}