Contributions to Mineralogy and Petrology最新文献

{"title":"Geometry controls on the structure and geochemistry of olivine low-angle grain boundaries","authors":"Dimitrios Dimitriou,&nbsp;Steven M. Reddy,&nbsp;Denis Fougerouse,&nbsp;David W. Saxey,&nbsp;Katy Evans,&nbsp;Tommaso Tacchetto,&nbsp;Katharina Marquardt","doi":"10.1007/s00410-026-02318-9","DOIUrl":"10.1007/s00410-026-02318-9","url":null,"abstract":"<div>\u0000 \u0000 <p>Olivine low-angle grain boundaries (LAGBs) influence the upper mantle properties, but the role of geometry in their structure and chemical composition remains largely unexplored. Here, we characterise and compare three tilt LAGBs with a 4.5° misorientation angle but different misorientation axes in a mantle xenolith. Electron backscatter diffraction (EBSD) was used to characterise three olivine grains, containing one LAGB aligning with the (001)[100] slip system, and two LAGBs with (010)[100] slip. Within the (010)[100] LAGBs, transmission electron microscopy (TEM) shows dislocation cores regularly spaced at 5.8 nm. Direct dislocations imaging in the (001)[100] LAGB was hindered by lamella orientation. Atom probe tomography (APT) reveals segregation of Al, Ca, Fe, H and Ti to the LAGBs, accompanied by Mg depletion. In the (010)[100] LAGBs, the segregated elements are concentrated in linear arrays (~ 5.8 nm spacing), consistent with segregation to dislocations. In the (001)[100] LAGBs, although segregated elements appear evenly distributed, 2D profiles show regularly spaced features at ~ 4.8 nm along the boundary, indicative of dislocation spacing. Interfacial excess calculations reveal differences in elemental segregation between boundaries. The (001)[100] LAGB has greater H segregation, while the LAGB in the seemingly smaller grain exhibits decreased Al, Ca and Fe enrichment. These findings suggest that LAGB geometry influences elemental segregation. Because these geometries are associated with specific mantle fabrics, the segregation patterns may influence differences in phase transitions, creep behaviour, electrical conductivity, and seismic properties in the upper mantle.</p>\u0000 </div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"181 4","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00410-026-02318-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147643000","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 note on surface energy and phase boundary energy relationships","authors":"A. E. Boudreau","doi":"10.1007/s00410-026-02316-x","DOIUrl":"10.1007/s00410-026-02316-x","url":null,"abstract":"<div>\u0000 \u0000 <p>The Gibbs free surface energy (or simply the <i>surface energy</i>,<i> σ</i>) is the excess free energy that arises from the mismatch and unsatisfied bonds and local lattice distortions at the surface of a phase (and especially minerals) that contributes a positive contribution to the total free energy of that phase. The phase boundary Gibbs free energy (<i>boundary energy</i>,<i> γ</i>) is that excess positive free energy that is present at the contact of two phases. Both play an important role in the crystallization of rocks ranging from high temperature igneous to sedimentary rocks. However, an explicit description of the relationship between the two is rarely noted in the geologic literature. Ignoring deformational effects, the energy to create two surfaces in contact can be considered the sum of the two surface energies <i>in vacuo</i> (<span>(:{sigma:}_{iv}^{alpha:}+:{sigma:}_{iv}^{beta:})</span>) less the binding energy (<b><i>B</i></b>_{<i>α−β</i>}) gained when the two phases <i>α</i> and <i>β</i> are brought together and new bonds are formed. The boundary energy, <span>(:{gamma:}_{alpha:-beta:})</span>, is then: <span>(:{gamma:}_{alpha:-beta:}=left({sigma:}_{iv}^{alpha:}+::{sigma:}_{iv}^{beta:}right)-{varvec{B}}_{alpha:-beta:})</span>. The boundary energy can then be shown to be the sum of the residual or uncompensated <i>in vacuo</i> surface energy of both grains, <span>(:{sigma:}_{alpha:-beta:}^{alpha:})</span> and <span>(:{sigma:}_{alpha:-beta:}^{beta:})</span>: <span>(:{gamma:}_{alpha:-beta:}={sigma:}_{alpha:-beta:}^{alpha:}+:{sigma:}_{alpha:-beta:}^{beta:})</span>. Using these definitions, one can derive common expressions such as the Ostwald-Freundlich equation that define solution concentration as a function of mineral grain size. Owing to the independent nature of surface energies and the boundary energy, they can affect the pattern-forming behavior of the system (e.g., periodic precipitation or mineral clustering) that may not be evident from consideration of either alone.</p>\u0000 </div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"181 4","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147642999","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":"Þingmúli revisited: New zircon-based perspectives on rhyolite petrogenesis in Iceland","authors":"Tenley J. Banik,&nbsp;Tamara L. Carley,&nbsp;Cameron D. Essex,&nbsp;Gabriella M. Montano","doi":"10.1007/s00410-026-02313-0","DOIUrl":"10.1007/s00410-026-02313-0","url":null,"abstract":"<div>\u0000 \u0000 <p>Þingmúli (Thingmuli), an extinct volcano in eastern Iceland, has long been an archetype for fractional crystallization of tholeiitic basalt to produce rhyolite. However, a recent re-examination of Þingmúli suggests that some silicic magmas were produced under more oxidizing conditions from a combination of magma mixing and assimilation, thereby indicating two petrogenetic pathways. We present the first zircon-based analyses from Þingmúli to evaluate the extent to which the zircon record corroborates these recent findings. Zircon U-Pb age dates of ~ 8.5–10 Ma agree with published whole-rock and regional values. Zircon ε_Hf ranges from ~ + 13.6 to 16.3; zircon δ^<b>18</b>O is largely restricted to ~ 3.1–3.9‰, with crystals from one sample averaging ~ 2‰. Trace elements reveal two distinct compositional groups: Group 1—common at Þingmúli but rare in the Iceland zircon record; and Group 2, which is representative of typical Icelandic zircon, but under-represented at Þingmúli. The rhyolite from which Group 1 zircon crystallize results from extreme fractional crystallization of incompatible-element enriched melt with variable, but probably small, amounts of unusually low-¹⁸O material. Group 2 zircon, with compositions distinct from Group 1 (notably, Eu/Eu*&gt;0.1), reveal a different origin story—one counter to the traditionally held view of petrogenesis at Þingmúli. A combination of variable mantle input composition and differentiation dominated by AFC processes involving crustal input are required to generate the evolved melts from which Group 2 zircon crystallized. This dynamic petrogenesis, common in active Icelandic central volcanic systems, dominates rhyolite petrogenesis at Þingmúli.</p>\u0000 </div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"181 4","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00410-026-02313-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147642644","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":"Ti solubility in biotite at low pressure in metapelitic systems: the Torres del Paine case","authors":"Maria M. Ariza-Acero,&nbsp;Lukas P. Baumgartner,&nbsp;C. Tom Foster,&nbsp;Marisa D. Acosta,&nbsp;Jo Moore,&nbsp;Jack Gillespie,&nbsp;Robert Bodner,&nbsp;Guillaume Siron","doi":"10.1007/s00410-026-02305-0","DOIUrl":"10.1007/s00410-026-02305-0","url":null,"abstract":"<div>\u0000 \u0000 <p>The Torres del Paine Intrusive Complex (TPIC) is a shallowly emplaced pluton surrounded by a well-defined contact aureole, providing an ideal setting to test Ti-in-biotite thermometry. We compare existing Ti-in-biotite thermometers with phase petrology constraints and found that they systematically overestimate peak metamorphic temperatures. This discrepancy arises from a significant increase in Ti solubility at low pressures <span>((&lt;1)</span> kbar). In fact, we demonstrate that a pressure difference of <span>(sim 0.25)</span> kbar within the aureole leads to an increase of 0.1 a.p.f.u. in Ti content, suggesting that pressure plays a key role in Ti incorporation at these low pressures. At lower pressures, the Ti-oxy substitution becomes saturated, and Ti incorporation is dominated by a Ti-spinel exchange mechanism. Additionally, textural and chemical analyses reveal that composition vary between small domains of a few hundred micrometers, indicating that local compositional heterogeneities significantly influences Ti content in biotite, even when a Ti-oxide and an Al-rich silicate are nearby. Finally, biotite starts growing near to the biotite-in isograd, and keeps on growing, so that its composition does not fully adjust to the peak composition due to the short metamorphic event. These findings highlight that both pressure and temperature influence the Ti content in biotite. The application of Ti-in-biotite thermometry requires careful consideration of equilibrium domains and growth kinetics.</p>\u0000 </div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"181 4","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00410-026-02305-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147606634","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":"Upper-pressure stability and thermochemical properties of synthetic marialite and its application to calculating paleobrine NaCl concentrations","authors":"Alexander J. Kerstanski,&nbsp;David M. Jenkins,&nbsp;Johannes Hammerli","doi":"10.1007/s00410-026-02311-2","DOIUrl":"10.1007/s00410-026-02311-2","url":null,"abstract":"<div>\u0000 \u0000 <p>Marialite (Na₃Al₃Si₉O₂₄·NaCl), the chloride end-member of the scapolite mineral group, is important for determining the chloride content of a paleofluid from which Cl-bearing scapolite formed as well as its potential role in the geochemical cycling of chlorine in tectonically active zones. Experiments on the upper-pressure stability of synthetic marialite breaking down to jadeite + coesite + halite at high pressures were done using a multi-anvil press in the range of 2.6–4.0 GPa and 1050–1250 °C for durations of 1–48 h. The boundary of this reaction was located along a straight line running from 2.8 GPa and 1050 °C to 3.5 GPa and 1250 °C. These data were then combined with data on the lower-thermal stability of marialite from this study and from previous work, along with published thermophysical data on synthetic marialite, to derive thermodynamic data for end-member marialite. The resultant 298 K and 1 atm value for the enthalpy of formation (<span>(varDelta{H}_{f}^{text{o}})</span>) is -12,164.03 ± 4.7 kJ/mol and for the third-law entropy (<i>S°</i>) is 760.34 ± 3.8 J/K·mol for a volume of 329.47 cm³/mol. These values provide good fits to the experimental data. The relatively high-temperature, high-pressure, and extremely high-salinity conditions needed to form end-member marialite means that albitite, rather than marialite, will tend to form at near-surface hydrothermal conditions. Scapolite is stabilized to typical intermediate-grade metamorphic conditions because of substantial solid solution of marialite with other scapolite components (i.e., meionite and silvialite). Thermochemical data presented here can be used to determine the NaCl content of the paleobrine that formed Cl-bearing scapolite in, for example, the Dana Hill metagabbro of the northwest Adirondack Mountains, New York, which was found to be in the range of 32–56 wt% NaCl equivalent.</p>\u0000 </div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"181 4","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00410-026-02311-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147561984","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":"Mantle dunites archive multistage melt metasomatism under a fossil slow-ultraslow spreading center: an example from the Tibetan Xigaze ophiolite","authors":"Li Wang,&nbsp;Qing Xiong,&nbsp;Hong-Kun Dai,&nbsp;Xiang Zhou,&nbsp;Hong-Da Zheng,&nbsp;Hao-Qin Sun,&nbsp;Yi-Cong Li,&nbsp;Long-Fei Xue,&nbsp;Alessio Sanfilippo,&nbsp;Valentin Basch,&nbsp;Jian-Ping Zheng","doi":"10.1007/s00410-026-02308-x","DOIUrl":"10.1007/s00410-026-02308-x","url":null,"abstract":"<div>\u0000 \u0000 <p>Previous studies on oceanic crust have revealed the diversity of mantle melts in oceanic lithosphere, but their origin within oceanic mantle and initial composition remain unclear. The Dazhuka dunitic channels within the deep mantle section of the Xigaze ophiolite (South Tibet), which has been interpreted to have formed in a Neo-Tethyan slow-ultraslow spreading center, present ideal targets to explore the origin of oceanic mantle melts and the relevant processes. Petrographic characteristics and geochemical data identify three distinct types of dunites, recording complex melt types and two-stage evolution processes. In stage 1, a melt/rock interaction likely occurring at the top of the asthenosphere between silica-undersaturated melts and wall-rock harzburgites caused a rapid decrease in orthopyroxene contents, an increase in olivine grain size, as well as elevated whole-rock MgO contents (47.9–50.8 wt.%) and spinel Cr# (0.46–0.83). In addition, the elevation of clinopyroxene Ca/Al ratios (6.74–54.8) and Mg# (0.93–0.96) within type 2 dunites suggests that small amounts of carbonatitic components (~ 0.4 wt.%) possibly coexisted with the silica-undersaturated melts, causing gradual dunitization of wall-rock harzburgites. In stage 2, the occurrence of disseminated pyroxenes and spinels crosscutting the dunites, along with the increased olivine Ca contents (492–1745 ppm) and spinel TiO₂ contents (0.20–0.35), indicates that MORB-like melts reused the dunitic channels and resulted in the refertilization of the channel system. Our study highlights that, under oceanic slow-ultraslow spreading centers, the dunitic channels can act as critical archives of mantle melt evolution and thus a valid alternative for constraining the heterogeneity of the asthenosphere.</p>\u0000 </div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"181 4","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147560939","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":"Microstructural investigations on the preservation mechanisms of intergranular coesite in UHP eclogite from Yangkou Bay, Sulu Region","authors":"Jinyu Zheng,&nbsp;Tao Chen,&nbsp;Junfeng Zhang,&nbsp;Lu Wang,&nbsp;Wenlong Liu,&nbsp;Feng Shi,&nbsp;Xiaohu Xuan,&nbsp;Mingxing Gong,&nbsp;Zhe Gong","doi":"10.1007/s00410-026-02315-y","DOIUrl":"10.1007/s00410-026-02315-y","url":null,"abstract":"<div>\u0000 \u0000 <p>Intergranular coesite found in ultra-high pressure (UHP) eclogites provides critical insights into deep subduction and exhumation processes. However, its plastic deformation behavior remains not well understood. We report here the detailed deformation micro-ultramicrostructure of both intragranular and intergranular coesite, along with its surrounding minerals in UHP eclogites from the Yangkou Bay, Sulu UHP terrane. A combination analysis of electron backscatter diffraction (EBSD), focused ion beam (FIB), and transmission electron microscopy (TEM) was performed in this study. EBSD analysis reveals that retrograde quartz replacing both types of coesite displays palisade textures, whereas the quartz replacing intergranular coesite further develops bulging mosaic textures. TEM analysis shows coesite is nearly dislocation-free, while retrograde quartz exhibits abundant dislocations. The defect structures in retrograde quartz include free dislocations, dislocation tangles, and subgrain boundaries. The dislocation density, quantified from total dislocations, indicates that the retrograde quartz experienced plastic deformation under differential stress. Intragranular palisade quartz records 628–999 MPa differential stress, exceeding intergranular palisade values (517 MPa; 154–165 MPa with Brazil twins) and mosaic quartz (345–657 MPa). Lower differential stress in the intergranular coesite indicates grain boundary facilitated pressure release. Notably, the intergranular coesite is free of water-related defects; however, they were detected in the surrounding retrograde quartz. Based on these results, we proposed a “stress-controlled pressure vessel” model to explain the preservation mechanism of intergranular coesite, which can only survive among 2–3 omphacite grains during exhumation. In addition to a dry preservation environment, differential stress is a more important key factor governing the preservation of intergranular coesite. Our findings provide critical micro- to ultra-microstructural insights into the preservation mechanisms of this coesite type.</p>\u0000 </div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"181 4","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147560938","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":"An example of crustal assimilation in a basaltic cumulate mush, hypersthene gabbro, Ardnamurchan, Scotland","authors":"James M. D. Day","doi":"10.1007/s00410-026-02304-1","DOIUrl":"10.1007/s00410-026-02304-1","url":null,"abstract":"<div>\u0000 \u0000 <p>Assimilation of crust by hot basaltic liquids changes physical magma characteristics. Advances have been made in understanding assimilation through isotope and trace element geochemistry, thermodynamic models and theory. Physical examples of assimilation in basaltic magma chambers, however, are less common due to limited exposures capturing the processes. Here, field observations, petrology and bulk rock chemistry, including ⁸⁷Rb-⁸⁷Sr data, are reported for lithologies, including sedimentary blocks and hornfels, within the hypersthene gabbro of the Paleogene-aged Ardnamurchan Igneous Complex, Scotland. Mesozoic sediments and Neoproterozoic Moine schist, into which the hypersthene gabbro intruded, have radiogenic ⁸⁷Sr/⁸⁶Sr (&gt; 0.71). Significant initial Sr isotope variability in the hypersthene gabbro and autoliths (0.70402–0.70921) demonstrates inhomogenous and extensive (&gt; 10%) assimilation in some instances. Mineralogy and radiogenic initial ⁸⁷Sr/⁸⁶Sr (0.70753–0.71030) of hornfels masses are consistent with their derivation by replacement after sedimentary protoliths. Partial assimilation of sediment during cumulate formation accounts for variable quantities of crustal assimilation in the hypersthene gabbro and implies concomitant hydration of the magma. Incomplete assimilation of stoped and foundered sediments enabled greater extents of assimilation, while also enhancing accommodation space for intrusion emplacement. Crustal assimilation may also have played a role in the layering and structure in the intrusion due to cooling and modifying melt composition within a crystal mush. Larger or hotter basaltic magma chambers, and lavas erupted in continental flood basalts or in oceanic settings show variable chemical evidence for assimilation. Consequently, crustal contamination during formation of crystal mushes is likely to be a ubiquitous process in basaltic feeder intrusions.</p>\u0000 </div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"181 4","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147441462","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":"Impact of intragrain chemical heterogeneities on 40Ar/39Ar and 87Rb–87Sr white mica dates","authors":"Vidar Jakobsson,&nbsp;Richard Spikings,&nbsp;Martin Kutzschbach,&nbsp;Bruno Ribeiro,&nbsp;Willis Hames,&nbsp;Alfons Berger,&nbsp;Tobias Erhardt,&nbsp;Wolfgang Müller","doi":"10.1007/s00410-026-02299-9","DOIUrl":"10.1007/s00410-026-02299-9","url":null,"abstract":"<div>\u0000 \u0000 <p>White mica commonly yields younger ⁴⁰Ar/³⁹Ar dates than ⁸⁷Rb–⁸⁷Sr isochron dates in greenschist to amphibolite facies rocks, which are often interpreted as ⁴⁰Ar/³⁹Ar cooling dates. However, recent petrochronological studies showed that younger ⁴⁰Ar/³⁹Ar dates can result from chemical re-equilibration. We investigate the frequency and conditions under which white mica chemically (re)equilibrates during an orogenic cycle in common upper crustal rocks and its implications for ⁴⁰Ar-loss and ⁸⁷Sr/⁸⁶Sr-(re)equilibration. We have applied double-dating mapping by in-situ ⁸⁷Rb–⁸⁷Sr and ⁴⁰Ar/³⁹Ar geochronology, quantitative chemical mapping, and δ¹⁸O analysis to Mesoproterozoic metasedimentary and igneous rocks from the Black Hills, South Dakota. Intragrain chemical disequilibrium is pervasive in white mica, with primary phenocrystic and porphyroblastic compositions overprinted by reaction-grown phases along cleavage planes and grain boundaries. Re-equilibration involved metasomatic exchange of incompatible elements (Ar, Na, Rb, Sr, Cs, Ba, B, La and Li) during fluid-assisted alteration in a meta-tuff and the Harney Peak Granite. ⁸⁷Rb–⁸⁷Sr white mica isochron dates of 1763.24 ± 17.05 Ma and 1677.95 ± 9.99 Ma for the meta-tuff and the Harney Peak Granite, respectively, are a consequence of high-temperature chemical equilibrium. In contrast, ⁴⁰Ar/³⁹Ar dates of reaction-grown white mica of 1300.36 ± 15.84 Ma and 1284.89 ± 4.87 Ma, record fluid-driven re-equilibration at 364 ± 50 °C (chlorite-thermometry). These results indicate that fluid-assisted processes can reset ⁴⁰Ar/³⁹Ar dates in white mica, while having a minor effect on the ⁸⁷Rb–⁸⁷Sr system, rendering cooling-age interpretations ambiguous when they lack petrological control.</p>\u0000 </div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"181 3","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00410-026-02299-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147441164","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":"Protracted evolution of crustal-derived carbonatites in high-grade metamorphic terranes","authors":"Shi-Ying Wang,&nbsp;P. L. Dharmapriya,&nbsp;Tian-Yi Li,&nbsp;Jing Wang,&nbsp;Sanjeewa P. K. Malaviarachchi,&nbsp;Ben-Xun Su","doi":"10.1007/s00410-025-02286-6","DOIUrl":"10.1007/s00410-025-02286-6","url":null,"abstract":"<div><p>Crustal-derived carbonatites are increasingly recognized, yet their evolutionary history remains inadequately constrained. This study integrates U–Pb geochronology of multiple minerals with element compositions and C–O isotope analyses to elucidate the temporal evolution of the Balangoda carbonatites, a recently confirmed crustal-derived body in the Highland Complex, Sri Lanka. The carbonatites, intruding high-grade metamorphic gneisses, dominate in calcite with variable amounts of phlogopite, apatite, dolomite, clinopyroxene, olivine, and spinel, and occur as coarse-grained and pegmatitic types. Calcite from both types exhibits similar δ¹³C values (–1.83‰ to 0.41‰) and a broader δ¹⁸O range (17.22‰ to 22.86‰) compared to Sri Lankan marbles, indicating a metamorphic carbonate protolith. In pegmatitic carbonatites, systematic decreases in δ¹⁸O and mineral inclusion abundance from blue and white to yellow calcite indicate evolving fluid conditions during protracted magma evolution. Concordia U–Pb ages of zircon (522.8 ± 9.6 Ma) and calcite (524 ± 29 Ma) in sample 23C-BC, along with a weighted mean ²⁰⁷Pb/²⁰⁶Pb titanite age (548 ± 12 Ma), constrain the timing of crystallization. Whereas, the younger apatite age (487.4 ± 8.5 Ma) from the same sample records a protracted cooling history. Additional calcite ages (~ 525 Ma) and consistent apatite ages (521.9 ± 8.4 Ma; 515.8 ± 9.8 Ma) corroborate this extended magmatic evolution. These multi-mineral ages are consistent with the regional high-grade metamorphism (660–500 Ma) followed by protracted cooling to ~ 480 Ma in the Highland Complex. This supports a model of carbonatite magma genesis through anatexis of dolomitic marbles under prolonged high-temperature metamorphism, with antiskarn processes removing dolomitic components. The Balangoda carbonatites, in conjunction with global occurrences, exemplify that long-lived generation and evolution are typical of crustal-derived carbonatites, linked closely to regional metamorphic events.</p></div>","PeriodicalId":526,"journal":{"name":"Contributions to Mineralogy and Petrology","volume":"181 3","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147441165","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}