Geochemistry Geophysics Geosystems最新文献_第4页

Deep Crustal Magma-Water Interaction During Oceanic Core Complex Termination of the Godzilla Megamullion in the Parece Vela Basin parce Vela盆地哥斯拉巨兽洋核复合体终止期间深部地壳岩浆-水相互作用

IF 3.3 2区地球科学

Geochemistry Geophysics Geosystems Pub Date : 2026-09-07 DOI: 10.1029/2026GC012927

Han-Tao Chi, Guo-Liang Zhang, Ji Zhang, Chang-Ming Lu

{"title":"Deep Crustal Magma-Water Interaction During Oceanic Core Complex Termination of the Godzilla Megamullion in the Parece Vela Basin","authors":"Han-Tao Chi, Guo-Liang Zhang, Ji Zhang, Chang-Ming Lu","doi":"10.1029/2026GC012927","DOIUrl":"https://doi.org/10.1029/2026GC012927","url":null,"abstract":"Oceanic Core Complexes (OCCs) in back-arc basins are not as thoroughly investigated, and their termination processes remain poorly understood. The Godzilla Megamullion is the largest known ceased OCC on Earth, yet magmatic and hydrothermal records from its termination are lacking. Here, we present an integrated study of gabbroic and basaltic rocks from the termination of the Godzilla Megamullion. The zircon U-Pb age-dating of gabbroic rocks constrains the latest magmatic activity to 7.93 ± 0.14–8.23 ± 0.04 Ma, falling below the regional regression line and suggesting a decline in spreading rate prior to cessation of the back-arc basin. These gabbroic rocks record anomalously high water contents and H2O/Ce ratios in clinopyroxene and calculated parental melts, suggesting synorogenic magma-seawater interactions during ridge termination. The high-temperature amphiboles (640°C–845°C) in these gabbroic rocks are also consistent with deep activities of seawater along the detachment faults. We propose that magma-seawater interactions played an important role in the formation and evolution of the Godzilla OCC.","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"27 9","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026GC012927","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148942774","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}

引用次数: 0

Investigating Layered Cratonic Lithosphere in the Fennoscandian Shield 芬诺斯坎地盾层状克拉通岩石圈研究

IF 3.3 2区地球科学

Geochemistry Geophysics Geosystems Pub Date : 2026-09-04 DOI: 10.1029/2026GC013210

Yiran Huang, Colleen A. Dalton, Karen M. Fischer

{"title":"Investigating Layered Cratonic Lithosphere in the Fennoscandian Shield","authors":"Yiran Huang, Colleen A. Dalton, Karen M. Fischer","doi":"10.1029/2026GC013210","DOIUrl":"https://doi.org/10.1029/2026GC013210","url":null,"abstract":"Cold, thick, and chemically depleted lithosphere with high seismic velocity and low attenuation characterizes continental cratons. However, discrepancies between xenolith-based thermal constraints and those inferred from surface-wave seismic models, together with the widespread observation of mid-lithosphere discontinuities, challenge the traditional view of a simple cratonic lithospheric structure. Improving constraints on lithospheric layering is therefore essential for understanding the thermal and compositional structure of the cratonic upper mantle. In this study, we develop a three-dimensional model of vertically polarized shear-wave velocity (Vsv) in Fennoscandia through the joint inversion of Rayleigh wave phase velocities and S-to-P receiver functions, resolving both absolute velocities and strong vertical gradients. Compared to models derived from phase velocities alone, our results show that the highest velocities (>4.7 km/s) are located deeper, predominantly at ∼140–210 km depth. We compare the seismic model of the Fennoscandia craton interior with Vsv predictions based on depleted peridotite compositions along xenolith-derived geotherms. After accounting for anelasticity and radial anisotropy, we find that the high velocities observed deeper than ∼150 km can be explained with a moderate diamond fraction (∼0.5 vol.%) combined with a colder geotherm than estimates based on standard xenolith thermometry, while remaining consistent with xenolith constraints. In the shallow lithosphere, slower-than-predicted shear-wave velocities are best explained by the combined effects of radial anisotropy and the presence of carbonate and/or hydrous minerals introduced by metasomatism. The layered seismic structure revealed in this study provides new insights into the thermal and compositional architecture of cratonic lithosphere and its formation and modification.","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"27 9","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026GC013210","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148942385","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}

引用次数: 0

Past the First Date: Ensemble Concordant–Discordant Comparison for Zircon Pb-Loss Analysis 超过第一日期：锆石Pb-Loss分析的整体一致性-不一致性比较

IF 3.3 2区地球科学

Geochemistry Geophysics Geosystems Pub Date : 2026-08-31 DOI: 10.1029/2026GC013184

Lucy M. Mathieson, Christopher L. Kirkland

{"title":"Past the First Date: Ensemble Concordant–Discordant Comparison for Zircon Pb-Loss Analysis","authors":"Lucy M. Mathieson, Christopher L. Kirkland","doi":"10.1029/2026GC013184","DOIUrl":"https://doi.org/10.1029/2026GC013184","url":null,"abstract":"Zircon uranium–lead (U–Pb) geochronology is a cornerstone of Earth science for resolving the timing of deep-time processes, yet the U–Pb system does not always behave as a closed chronometer. Selective loss of radiogenic Pb during fluid alteration or thermal disturbance can shift isotopic ages and generate discordant analyses. Some zircon data sets may preserve more than one Pb-loss episode, yet many Pb-loss modeling approaches return a single “best” time of Pb-loss. The concordant–discordant comparison (CDC) test estimates Pb-loss timing by finding the modeled disturbance age at which reconstructed discordant analyses best match the concordant population. Here, we extend the CDC framework to retain supported local optima across Monte Carlo realizations rather than reducing each realisation to a single optimum, and report 95% stability bounds that describe run-to-run repeatability in peak position rather than geological age uncertainty. This redesign can resolve the timing of multiple Pb-loss episodes, recovering overprinting metamorphic, hydrothermal, or magmatic events. Testing the method against simulated zircon U–Pb data sets with prescribed Pb-loss histories, we find that the ensemble CDC yields the lowest overall median absolute error of the benchmarked modeling approaches (19 Myr) and assigns age estimates to 27 of 36 true events. Errors are lowest for six single-event benchmark examples, with a 90th-percentile absolute error of 11 Myr, increasing to 83 Myr in overlapping multi-event cases. Applied to an Archean Yilgarn granite, the ensemble resolves two Pb-loss peaks at 454 and 1113 Ma, consistent with regional Pan-African cooling and the Mesoproterozoic Warakurna Large Igneous Province respectively.","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"27 9","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026GC013184","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148943600","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}

引用次数: 0

Petrogenesis and Tectonic Implication of the Newly Identified Rhyacian and Orosirian Orthogneisses in the Northwestern Part of the Gyeonggi Massif (Soyeonpyeongdo and Ganghwado Areas), South Korea: Constrained From Whole-Rock Geochemistry and Zircon U-Pb-Hf Isotopic Compositions 韩国京畿地块西北部（Soyeonpyeongdo和ganghwa地区）新发现的流纹和奥陶纪正长岩的岩石成因及构造意义：全岩地球化学和锆石U-Pb-Hf同位素组成的约束

IF 3.3 2区地球科学

Geochemistry Geophysics Geosystems Pub Date : 2026-08-31 DOI: 10.1029/2026GC013080

Seung Hwan Lee, Deung-Lyong Cho, Jeong-Yeong Park, Sung Won Kim, Byung Choon Lee, Mingguo Zhai

{"title":"Petrogenesis and Tectonic Implication of the Newly Identified Rhyacian and Orosirian Orthogneisses in the Northwestern Part of the Gyeonggi Massif (Soyeonpyeongdo and Ganghwado Areas), South Korea: Constrained From Whole-Rock Geochemistry and Zircon U-Pb-Hf Isotopic Compositions","authors":"Seung Hwan Lee, Deung-Lyong Cho, Jeong-Yeong Park, Sung Won Kim, Byung Choon Lee, Mingguo Zhai","doi":"10.1029/2026GC013080","DOIUrl":"https://doi.org/10.1029/2026GC013080","url":null,"abstract":"The Gyeonggi Massif is one of the major Precambrian basements in the Korean Peninsula where Paleoproterozoic orthogneiss and paragneiss were widely exposed. In this study, newly identified Rhyacian to Orosirian meta-igneous rocks from the northwestern Gyeonggi Massif (Soyeonpyeongdo and Ganghwado areas) were investigated to elucidate their petrogenesis and tectonic implications based on zircon U–Pb–Hf isotopic data and whole-rock geochemistry. The garnet-bearing amphibole granite gneiss and biotite granite gneiss in the Soyeonpyeongdo area emplaced at ca. 2.06 Ga and 1.88 Ga, respectively, whereas the tonalite gneiss in the Ganghwado area formed at ca. 1.93 Ga. The 2.06 Ga garnet-amphibole granite gneiss shows both I-type and A2-type features enriched in LILE and depleted in Nb–Ta, indicating generation in an arc-related extensional regime. The 1.93 Ga tonalitic gneiss exhibits adakitic characteristics, negative εHf(t) values (−8.2 to −4.9), and thickened crustal signatures (42–74 km), which are consistent with derivation from Archean mafic lower crust thickened during a regional syn-collisional stage. The 1.88 Ga biotite granite gneiss displays metaluminous to weakly peraluminous I- and A2-type features with slightly negative εHf(t) values (−1.7 to +0.6), implying formation in a post-collisional extensional setting. These successive magmatic events (2.06–1.85 Ga) in the Gyeonggi Massif are temporally and geochemically comparable to the Rhyacian–Orosirian magmatism in the Liao–Ji Belt of the eastern North China Craton. Therefore, the northwestern Gyeonggi Massif recorded a Paleoproterozoic tectono-magmatic evolution broadly comparable to that of the Liao–Ji Belt.","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"27 9","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026GC013080","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148943599","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}

引用次数: 0

Geochronological Constraints on Diachronous Post-Collisional Slab Breakoff Along the Paleo-Tethyan Sutures 古特提斯缝合线碰撞后历时板块断裂的地质年代学约束

IF 3.3 2区地球科学

Geochemistry Geophysics Geosystems Pub Date : 2026-08-30 DOI: 10.1029/2025GC012898

Min Liu, Hao Wu, Xi-Jun Liu, Rong-Guo Hu, Si-Nan Lv, Xiao-Xiao Hu, Yao Xiao, Hao-Dong Wei

{"title":"Geochronological Constraints on Diachronous Post-Collisional Slab Breakoff Along the Paleo-Tethyan Sutures","authors":"Min Liu, Hao Wu, Xi-Jun Liu, Rong-Guo Hu, Si-Nan Lv, Xiao-Xiao Hu, Yao Xiao, Hao-Dong Wei","doi":"10.1029/2025GC012898","DOIUrl":"https://doi.org/10.1029/2025GC012898","url":null,"abstract":"The slab breakoff model is a preferred geodynamic interpretation for post-collisional exhumation and associated magmatic flare-ups. In this study, rutile U–Pb dating of retrograde eclogites revealed distinct stages of exhumation along the Paleo-Tethyan sutures in southwest China. The studied samples yielded ages of 246.7 ± 8.5 and 239.7 ± 14.0 Ma in the Changning–Menglian suture zone, and 213.0 ± 10.0 and 205.6 ± 8.9 Ma in the Longmu Co–Shuanghu suture zone. These new rutile ages, along with published geochronological data for high-pressure (HP) metamorphic and igneous rocks along the Paleo-Tethyan sutures, reveal that Late Triassic tectonic exhumation was coeval with a regional magmatic flare-up. Our results suggest that the Late Triassic tectonomagmatic activity occurred in a post-collisional setting and was related to slab breakoff. The geochronological data for the HP metamorphic and igneous rocks show that the Late Triassic tectonomagmatic activity was diachronous along the suture. We propose that the spatiotemporal migration of these Late Triassic post-collisional tectonothermal events was controlled mainly by the initiation and progression of slab breakoff. The results provide new insights into the tectonic evolution of the Tethyan geodynamic system and improve our understanding of post-collisional tectonomagmatism in response to slab breakoff processes in a collision zone.","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"27 9","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GC012898","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148943436","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}

引用次数: 0

Comment on “Parameterizations of Clinopyroxene—Melt Trace Element Partition Coefficients” by Bédard, J. H. (2014) 对bassdard， J. H.（2014）“斜辉石质-熔体微量元素分配系数参数化”的评论

IF 3.3 2区地球科学

Geochemistry Geophysics Geosystems Pub Date : 2026-08-28 DOI: 10.1029/2026GC013224

Jean H. Bédard

{"title":"Comment on “Parameterizations of Clinopyroxene—Melt Trace Element Partition Coefficients” by Bédard, J. H. (2014)","authors":"Jean H. Bédard","doi":"10.1029/2026GC013224","DOIUrl":"https://doi.org/10.1029/2026GC013224","url":null,"abstract":"A better understanding of how trace element partition coefficients vary with melt and mineral composition, temperature, pressure, oxygen fugacity and fluid composition is essential to geochemical modeling of magmatic rocks. The Nernst partition coefficient D is the ratio of the concentration (by weight) of a trace element in a solid phase divided by the concentration of the same element in the equilibrium melt (D = Cs/Cm). Bédard (2014, https://doi.org/10.1002/2013gc005112) compiled partitioning data between clinopyroxene and silicate melt, and modeled these data to develop a set of predictive equations allowing clinopyroxene/melt partition coefficients to be predicted for most of the trace elements used in igneous petrology. A typographic error has been found in Table 2 of Bédard (2014, https://doi.org/10.1002/2013gc005112), where the value of the “d” coefficient of the equation needed to calculate the value of r0 for the M2 site was reported as being 0.0020599. The correct value is 0.00020599. I thank Carrie Soderman of Cambridge University for spotting this. I apologize to any who attempted to implement the lattice strain model from Bédard (2014, https://doi.org/10.1002/2013gc005112) using this incorrect coefficient, as it would have yielded erroneous results.","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"27 9","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026GC013224","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148823405","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}

引用次数: 0

Pattern Formation in Rocks 岩石模式的形成

IF 3.3 2区地球科学

Geochemistry Geophysics Geosystems Pub Date : 2026-08-28 DOI: 10.1029/2026GC013337

Jibamitra Ganguly

{"title":"Pattern Formation in Rocks","authors":"Jibamitra Ganguly","doi":"10.1029/2026GC013337","DOIUrl":"https://doi.org/10.1029/2026GC013337","url":null,"abstract":"This commentary concerns a two-part paper by Regenauer-Lieb et al. (2026a, 2026b) on pattern formation in deforming porous rocks. The theory developed in part I (https://doi.org/10.1029/2025GC012710) uses the general idea of Turing's reaction-diffusion model of morphogenesis based on interactions between two types of diffusible chemical species (morphogens). One species is an autocatalytic reactant and the other a more rapidly diffusing reaction product acting, respectively, as “activator” and “inhibitor” in the development of biological patterns. The new theory incorporates stress and cross-diffusion effects, the latter accounting for the fact that a specific flux is affected by all forces in the system (chemical gradients, temperature gradient etc.). For rocks, deformation and fluid pressure within the pores act as “activator” and “inhibitor,” with their roles depending on the state of deformation and permeability. In part II (https://doi.org/10.1029/2025GC012717) the authors discuss applications of their theory to explain the development of a variety of seemingly unrelated features in rocks. For the specific case of the banded iron formations, this theory does not, however, provide a stand-alone explanation for their origin but could be used to analyze stress effects on the banding that originated primarily from chemical processes. Finally, I offer suggestions for some future research directions that should be of interest to the Earth and Planetary Science communities.","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"27 9","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026GC013337","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148849256","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}

引用次数: 0

Insights Into Microscale Biomineralization in Deep-Sea Callogorgia Coral via Halogen Banding 深海Callogorgia珊瑚微尺度生物矿化的卤素条带研究

IF 3.3 2区地球科学

Geochemistry Geophysics Geosystems Pub Date : 2026-08-27 DOI: 10.1029/2026GC013193

Xuna Yin, Miaohong He, Xiaotong Peng, Kaiwen Ta, Hengchao Xu, Zhisen Liang, Xuefei Chen, Wenfeng Deng, Gangjian Wei

{"title":"Insights Into Microscale Biomineralization in Deep-Sea Callogorgia Coral via Halogen Banding","authors":"Xuna Yin, Miaohong He, Xiaotong Peng, Kaiwen Ta, Hengchao Xu, Zhisen Liang, Xuefei Chen, Wenfeng Deng, Gangjian Wei","doi":"10.1029/2026GC013193","DOIUrl":"https://doi.org/10.1029/2026GC013193","url":null,"abstract":"Halogen incorporation into coral carbonate skeletons serves as a valuable proxy for reconstructing paleoenvironments. However, the underlying mechanisms remain poorly understood. This study employed femtosecond laser ablation-inductively coupled plasma time-of-flight mass spectrometry (fs-LA-ICP-TOFMS) to perform multi-elemental (I, Br, P, Ca, Mg, Sr, S, Ba, and Fe) imaging of cross-sections from carbonate skeleton of deep-sea Callogorgia sp. coral (octocoral) collected from the Mariana Arc at a depth of 1,386 m. Previously unrecognized iodine-rich ring patterns and bromine-rich fan-like distributions were identified, likely influenced by the biological rhythms of polyps, such as polyp apoptosis-replacement or migration, which refresh the polyp-skeleton interface and facilitate halogen accumulation. Additionally, higher iodine and bromine concentrations were consistently observed in the calcitic layers compared to the aragonitic layer, suggesting that biological factors, particularly halogenated organics, dominate halogen incorporation, outweighing mineralogical controls. A comparison of halogen distributions between Callogorgia and bamboo corals demonstrated species-specific halogen incorporation patterns. These findings provide new insights into coral biomineralization, emphasizing the role of biological rhythms in skeletal formation and trace element incorporation.","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"27 9","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026GC013193","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148823395","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}

引用次数: 0

Tectonic Evolution and Crustal Growth of the East Kunlun Orogen, NW China: Insights From the Late Permian–Triassic Granitoids 东昆仑造山带构造演化与地壳生长：来自晚二叠世—三叠纪花岗岩类的启示

IF 3.3 2区地球科学

Geochemistry Geophysics Geosystems Pub Date : 2026-08-24 DOI: 10.1029/2026GC013011

Xiaodong Wang, Chao Wang, Liyun Zhang, Jinxiang Li, Yahui Yue, Lin Ding

{"title":"Tectonic Evolution and Crustal Growth of the East Kunlun Orogen, NW China: Insights From the Late Permian–Triassic Granitoids","authors":"Xiaodong Wang, Chao Wang, Liyun Zhang, Jinxiang Li, Yahui Yue, Lin Ding","doi":"10.1029/2026GC013011","DOIUrl":"https://doi.org/10.1029/2026GC013011","url":null,"abstract":"The East Kunlun Orogen (EKO) on the northern margin of the Tibetan Plateau experienced complex Late Paleozoic–Early Mesozoic tectono-magmatic activities associated with the subduction and closure of the Paleo-Tethys Ocean. Controversies remain regarding the timing and processes of the transition from subduction to collision and post-collision, as well as the mechanisms of continental crustal growth. This study presents zircon U–Pb ages (257–202 Ma), whole-rock geochemical data and Sr–Nd–Hf isotopic compositions for granitoids from the Nanshankou and Yeniugou areas in the EKO. The 257–246 Ma granitoids have variable Mg# values (34.9–49.7) and εHf(t) values (−4.9 to +1.1), and contain mafic enclaves, suggesting derivation from crust-mantle magma mixing. The ∼235 Ma granitoids have low Mg# values (30.7–32.7), and enriched Nd–Hf isotopic compositions, indicative of partial melting of mafic lower crust. The 203–202 Ma adakitic granitoids show positive εHf(t) values (0.0 to +4.7) and relatively high Mg# values (45.3–48.7), pointing to partial melting of delaminated mafic lower crust with involvement of mantle-derived magma. Integrating our results with regional geological data, we propose that the Paleo-Tethys Ocean in the EKO experienced long-term subduction during 278–240 Ma, accompanied by continental arc crustal growth. Following ocean closure at ∼240 Ma, the region entered a syn-collisional stage (240–220 Ma) dominated by crustal remelting. The EKO then evolved into the post-collisional stage at ∼220–200 Ma, with lithospheric delamination triggering vertical crustal accretion. This study constrains the subduction, collision, and post-collision evolution and crustal growth of the EKO from Middle Permian to Triassic.","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"27 8","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026GC013011","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148848804","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}

引用次数: 0

Evolution in Fluid Composition During Subduction 俯冲过程中流体成分的演化

IF 3.3 2区地球科学

Geochemistry Geophysics Geosystems Pub Date : 2026-08-21 DOI: 10.1029/2026GC013086

A. A. Helm, M. J. Caddick, R. J. Bodnar

{"title":"Evolution in Fluid Composition During Subduction","authors":"A. A. Helm, M. J. Caddick, R. J. Bodnar","doi":"10.1029/2026GC013086","DOIUrl":"https://doi.org/10.1029/2026GC013086","url":null,"abstract":"Fluid-rock reactions play important roles in seismicity, arc-magma chemistries, and volatile cycling at convergent plate boundaries. In subduction environments, metamorphic reactions involving hydrous fluids facilitate metasomatic alteration and mass transport. Fingerprinting the source of fluids that move across subducting lithologies is, however, challenging. We predict evolving mineralogy and fluid compositions during subduction along representative PT-paths, assessing closed and open system assumptions using phase assemblage modeling. Our calculations consider simplified hydrated harzburgite, hydrated mid-ocean ridge basalt, average subducted sediments, and subducted carbonates. Predict equilibrium mineralogy, fluid composition, and this allows us to identify fluid solute ratios that might be unique to a given source lithology or mineral breakdown reaction. In general, fluids derived from average subducting sediments are predicted to have a higher proportion of Na to Mg and Si than those derived from basalts at the same subduction PT condition. Fluids produced during deserpentinization of hydrated harzburgite contain a higher proportion of Mg and Ca. Together, these results help to constrain the potential sources of fluids that metasomatize subducting rocks and the overlying mantle wedge. Comparing results to examples of metasomatism and fluid inclusions from the rock record indicates that although imperfect, modeled major element fluid signatures can be an effective tool to assess the source lithology of altering fluids.","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"27 8","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026GC013086","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148784530","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}

引用次数: 0