Pub Date : 2025-11-25DOI: 10.1016/j.lithos.2025.108341
Quanshu Yan , Renjie Zhao , Xuefa Shi
During the subduction process, a portion of the subducted materials is returned or recycled to volcanic arcs. However, due to the diversity of subduction inputs, the mass balance relationship between subducted input and volcanic output requires further investigation. In this study, we analyzed lithium concentrations and Li-Sr-Nd-Pb isotopic compositions in subducting sediments and oceanic crusts from three drilling sites (IODP Sites U1381 and U1414, DSDP Site 495) in the segments being subducted along the Middle America Trench. The sediments exhibit significantly higher δ7Li values (1.9 ‰ to 11.7 ‰) compared to global subducting sediments (GLOSS), indicating the influence of biogenic components at low latitudes. The δ7Li values (4.4 ‰ to 9.6 ‰) of basaltic oceanic crust samples from all three sites are higher than those of the depleted mantle, suggesting they have undergone low-temperature basalt-seawater interaction. The Li-Sr-Nd-Pb isotopic compositions of samples from these drilling sites, combined with those of volcanic lavas from the Central American Arc reported in previous studies, indicate that different subduction components exert variable influences on the petrogenesis of volcanic arcs. Lavas in the northern Central American Arc were influenced by melts originating from subducted sediment and fluids derived from oceanic crust, whereas those in southern Central America were mainly influenced by melts from seamount components and eroded materials of the overlying plate.
{"title":"Li isotopic compositions of the Cocos Ridge segment subducting along the Middle America Trench and implications for the sub-arc geological process","authors":"Quanshu Yan , Renjie Zhao , Xuefa Shi","doi":"10.1016/j.lithos.2025.108341","DOIUrl":"10.1016/j.lithos.2025.108341","url":null,"abstract":"<div><div>During the subduction process, a portion of the subducted materials is returned or recycled to volcanic arcs. However, due to the diversity of subduction inputs, the mass balance relationship between subducted input and volcanic output requires further investigation. In this study, we analyzed lithium concentrations and Li-Sr-Nd-Pb isotopic compositions in subducting sediments and oceanic crusts from three drilling sites (IODP Sites U1381 and U1414, DSDP Site 495) in the segments being subducted along the Middle America Trench. The sediments exhibit significantly higher δ<sup>7</sup>Li values (1.9 ‰ to 11.7 ‰) compared to global subducting sediments (GLOSS), indicating the influence of biogenic components at low latitudes. The δ<sup>7</sup>Li values (4.4 ‰ to 9.6 ‰) of basaltic oceanic crust samples from all three sites are higher than those of the depleted mantle, suggesting they have undergone low-temperature basalt-seawater interaction. The Li-Sr-Nd-Pb isotopic compositions of samples from these drilling sites, combined with those of volcanic lavas from the Central American Arc reported in previous studies, indicate that different subduction components exert variable influences on the petrogenesis of volcanic arcs. Lavas in the northern Central American Arc were influenced by melts originating from subducted sediment and fluids derived from oceanic crust, whereas those in southern Central America were mainly influenced by melts from seamount components and eroded materials of the overlying plate.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"520 ","pages":"Article 108341"},"PeriodicalIF":2.5,"publicationDate":"2025-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145600465","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}
Pub Date : 2025-11-24DOI: 10.1016/j.lithos.2025.108343
Zhongyuan Liu , Fuhao Xiong , Han Zhao , Jie Gan , Junqing Mu , Yu Gan , Hui Li , Yaming Tian , Hao Zou
The physicochemical evolution of ore-forming fluids plays a central role in constraining the mineralization processes of skarn-type tungsten deposits, yet reconstructing this evolution remains challenging. The first reported large-scale Neoproterozoic Jianzidong W deposit in the western Yangtze Block, South China, hosts four generations of scheelite (SchI-SchIV), whose mineralogical textures, chemical compositions, and fluid inclusions collectively provide a continuous record of fluid evolution in skarn-type tungsten mineralization. Cathodoluminescence imaging and geochemical data show that SchI (prograde skarn stage) and SchIII (greisen stage) exhibit homogeneous textures with enriched rare earth elements (REEs), and negative Eu anomalies, resembling magmatic fluid inheritance. In contrast, SchII (retrograde skarn stage) and SchIV (quartz–calcite stage) display heterogeneous or incompletely zoned textures with enriched Mo, depleted ΣREE, and positive Eu anomalies, indicating fluid evolution in an open hydrothermal system. Mo contents and the Eu3+/Eu2+ ratios progressively increase from SchI, SchII, SchIII to SchIV-1, followed by a sharp drop in SchIV-2 to SchIV-3, suggesting a transition from oxidizing to reducing conditions. Fluid inclusions and HO isotope data indicate that SchI-1 and SchI-2 formed from high-temperature (avg. 450 °C) magmatic fluids in a relatively closed system, followed by fluid boiling at lower temperatures (avg. 320–350 °C), which drove SchI-3 precipitation. Subsequent fluid–rock interaction released Eu and Sr during plagioclase sericitization, forming SchI-2 and SchI-3 characterized by positive Eu anomalies. In an open system, F-rich magmatic fluid mixed with retrograde metamorphic fluid to produce SchI-4 and SchII at ∼300 °C under high fO₂, followed by cooling to ∼250 °C, forming SchIII. Finally, evolved F-rich fluids ascended along fractures, and additional cooling (∼180 °C) coupled with meteoric water input generated SchIV. These results highlight that progressive cooling, coupled with fluid–rock interaction in an oxidizing environment and localized boiling, were the dominant controls on fluid evolution and scheelite deposition in the skarn-type tungsten mineralization system.
{"title":"Decoding ore-forming fluids evolution through multi-stage scheelites: Insights from the first Neoproterozoic Jianzidong W deposit in the western Yangtze, South China","authors":"Zhongyuan Liu , Fuhao Xiong , Han Zhao , Jie Gan , Junqing Mu , Yu Gan , Hui Li , Yaming Tian , Hao Zou","doi":"10.1016/j.lithos.2025.108343","DOIUrl":"10.1016/j.lithos.2025.108343","url":null,"abstract":"<div><div>The physicochemical evolution of ore-forming fluids plays a central role in constraining the mineralization processes of skarn-type tungsten deposits, yet reconstructing this evolution remains challenging. The first reported large-scale Neoproterozoic Jianzidong W deposit in the western Yangtze Block, South China, hosts four generations of scheelite (SchI-SchIV), whose mineralogical textures, chemical compositions, and fluid inclusions collectively provide a continuous record of fluid evolution in skarn-type tungsten mineralization. Cathodoluminescence imaging and geochemical data show that SchI (prograde skarn stage) and SchIII (greisen stage) exhibit homogeneous textures with enriched rare earth elements (REEs), and negative Eu anomalies, resembling magmatic fluid inheritance. In contrast, SchII (retrograde skarn stage) and SchIV (quartz–calcite stage) display heterogeneous or incompletely zoned textures with enriched Mo, depleted ΣREE, and positive Eu anomalies, indicating fluid evolution in an open hydrothermal system. Mo contents and the Eu<sup>3+</sup>/Eu<sup>2+</sup> ratios progressively increase from SchI, SchII, SchIII to SchIV-1, followed by a sharp drop in SchIV-2 to SchIV-3, suggesting a transition from oxidizing to reducing conditions. Fluid inclusions and H<img>O isotope data indicate that SchI-1 and SchI-2 formed from high-temperature (avg. 450 °C) magmatic fluids in a relatively closed system, followed by fluid boiling at lower temperatures (avg. 320–350 °C), which drove SchI-3 precipitation. Subsequent fluid–rock interaction released Eu and Sr during plagioclase sericitization, forming SchI-2 and SchI-3 characterized by positive Eu anomalies. In an open system, F-rich magmatic fluid mixed with retrograde metamorphic fluid to produce SchI-4 and SchII at ∼300 °C under high <em>f</em>O₂, followed by cooling to ∼250 °C, forming SchIII. Finally, evolved F-rich fluids ascended along fractures, and additional cooling (∼180 °C) coupled with meteoric water input generated SchIV. These results highlight that progressive cooling, coupled with fluid–rock interaction in an oxidizing environment and localized boiling, were the dominant controls on fluid evolution and scheelite deposition in the skarn-type tungsten mineralization system.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"520 ","pages":"Article 108343"},"PeriodicalIF":2.5,"publicationDate":"2025-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145623267","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}
Pub Date : 2025-11-24DOI: 10.1016/j.lithos.2025.108344
Maximilian Dröllner , Christopher L. Kirkland , Katy Evans , Stuart Owen , Dinh Huu Minh
Large Igneous Provinces are often associated with economic mineralization, such as nickel (Ni), copper (Cu), and platinum group element (PGE) deposits. Exploring these mineral resources relies on understanding the chronology of processes involved in deposit formation, as the timing can significantly affect both the concentration and accessibility of valuable minerals, thereby informing effective exploration strategies. Here we present new multi-mineral laser ablation inductively coupled mass spectrometry (LA-ICP-MS) U–Pb geochronology from the Ban Phuc disseminated Ni sulfide deposit in the Ta Khoa District in northern Vietnam. Zircon and monazite U–Pb isotopes suggest that the Ban Phuc intrusion was emplaced during the c. 260 Ma Emeishan Large Igneous Province event, which likely also constrains the timing of crustal S incorporation and sulfide liquid segregation and migration. Additionally, U–Pb apatite geochronology indicates apatite (re-)crystallization at c. 220 Ma, in response to the Indosinian Orogeny. Integration of the new geochronological ages with mineralogical and textural features based on investigation of thin sections and SEM-based automated mineralogy supports a model in which hydrothermal alteration of the deposit was not related to auto-hydrothermal processes. Rather, the widespread metasomatic rocks of the deposit likely formed through pervasive and channelized fluid flow during hydrothermal alteration driven by regional metamorphism, post-dating crystallization. Ultimately, this temporal framework allows discussion of the fate and potential redistribution of Cu, Ni, and PGE within the deposit, with implications for genetic models and exploration strategies.
{"title":"Multi-mineral U–Pb geochronology of the Ban Phuc disseminated Ni sulfide deposit, Ta Khoa District, northern Vietnam: Implications for genesis and exploration","authors":"Maximilian Dröllner , Christopher L. Kirkland , Katy Evans , Stuart Owen , Dinh Huu Minh","doi":"10.1016/j.lithos.2025.108344","DOIUrl":"10.1016/j.lithos.2025.108344","url":null,"abstract":"<div><div>Large Igneous Provinces are often associated with economic mineralization, such as nickel (Ni), copper (Cu), and platinum group element (PGE) deposits. Exploring these mineral resources relies on understanding the chronology of processes involved in deposit formation, as the timing can significantly affect both the concentration and accessibility of valuable minerals, thereby informing effective exploration strategies. Here we present new multi-mineral laser ablation inductively coupled mass spectrometry (LA-ICP-MS) U–Pb geochronology from the Ban Phuc disseminated Ni sulfide deposit in the Ta Khoa District in northern Vietnam. Zircon and monazite U–Pb isotopes suggest that the Ban Phuc intrusion was emplaced during the c. 260 Ma Emeishan Large Igneous Province event, which likely also constrains the timing of crustal S incorporation and sulfide liquid segregation and migration. Additionally, U–Pb apatite geochronology indicates apatite (re-)crystallization at c. 220 Ma, in response to the Indosinian Orogeny. Integration of the new geochronological ages with mineralogical and textural features based on investigation of thin sections and SEM-based automated mineralogy supports a model in which hydrothermal alteration of the deposit was not related to auto-hydrothermal processes. Rather, the widespread metasomatic rocks of the deposit likely formed through pervasive and channelized fluid flow during hydrothermal alteration driven by regional metamorphism, post-dating crystallization. Ultimately, this temporal framework allows discussion of the fate and potential redistribution of Cu, Ni, and PGE within the deposit, with implications for genetic models and exploration strategies.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"522 ","pages":"Article 108344"},"PeriodicalIF":2.5,"publicationDate":"2025-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145692720","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}
The high-pressure (HP) eclogites in the Greater Himalayan Sequence (GHS) of the central Himalaya preserve multi-stage mineral assemblages and complex textures, offering crucial insights into the tectonothermal evolution of the Himalayan orogen. Especially, at the granulite-facies stage, the presence of non-equilibrated microdomains within representative mineral assemblages raises questions about the possibility of ultrahigh-temperature (UHT) conditions. We here report our detailed studies on the HP eclogites from the Yadong region in the central Himalaya by using a combined approach of petrography, mineral chemistry, zircon-titanite-rutile UPb age dating, phase equilibria modelling and geothermometry while also taking the advantage of automated mineralogy (AM) using TIMA. These eclogites (1) record prograde Ep-Amp eclogite-facies (M1: ∼ 680–700 °C and 17 kbar); (2) have been heated and buried to HP eclogite-facies (M2: ∼ 820–860 °C at 21 kbar), suggesting significant crustal thickening; (3) decompress heating to UHT granulite-facies (M3: ∼ 900–960 °C and 11–12 kbar) likely due to radiogenic heating in thickened crust, and (4) finally cool to medium-pressure (MP) amphibolite-facies (M4: ∼ 690–700 °C and 5–6 kbar). Metamorphic zircons yield the metamorphic age from M2 to M3 (∼ 17.8–17.3 Ma) and retrograde metamorphic M4 age (∼ 16 Ma) according to rare earth element characteristics. Titanite also records M4 age, while rutile records the later cooling age (∼ 13 Ma). Compared with the classic GHS transect in the central Himalaya, the upper and lower GHS in the Yadong region record different exhumation timing and rates affected by the Yadong fault activity, indicative of heterogeneous exhumation within the orogen. The AM method provides both mineral modes and compositions, which allow reconstruction of bulk-rock compositions on thin-section scales. The AM also facilitates recognition of accessory phases (e.g., zircons, titanite, rutile) for in situ analysis and dating.
{"title":"Metamorphic conditions and cooling history of the central Himalayan eclogites: A mineralogy and zircon-titanite-rutile UPb geochronology approach","authors":"Xin Dong , Zuo-lin Tian , Yao-ling Niu , Ze-ming Zhang","doi":"10.1016/j.lithos.2025.108338","DOIUrl":"10.1016/j.lithos.2025.108338","url":null,"abstract":"<div><div>The high-pressure (HP) eclogites in the Greater Himalayan Sequence (GHS) of the central Himalaya preserve multi-stage mineral assemblages and complex textures, offering crucial insights into the tectonothermal evolution of the Himalayan orogen. Especially, at the granulite-facies stage, the presence of non-equilibrated microdomains within representative mineral assemblages raises questions about the possibility of ultrahigh-temperature (UHT) conditions. We here report our detailed studies on the HP eclogites from the Yadong region in the central Himalaya by using a combined approach of petrography, mineral chemistry, zircon-titanite-rutile U<img>Pb age dating, phase equilibria modelling and geothermometry while also taking the advantage of automated mineralogy (AM) using TIMA. These eclogites (1) record prograde Ep-Amp eclogite-facies (M1: ∼ 680–700 °C and 17 kbar); (2) have been heated and buried to HP eclogite-facies (M2: ∼ 820–860 °C at 21 kbar), suggesting significant crustal thickening; (3) decompress heating to UHT granulite-facies (M3: ∼ 900–960 °C and 11–12 kbar) likely due to radiogenic heating in thickened crust, and (4) finally cool to medium-pressure (MP) amphibolite-facies (M4: ∼ 690–700 °C and 5–6 kbar). Metamorphic zircons yield the metamorphic age from M2 to M3 (∼ 17.8–17.3 Ma) and retrograde metamorphic M4 age (∼ 16 Ma) according to rare earth element characteristics. Titanite also records M4 age, while rutile records the later cooling age (∼ 13 Ma). Compared with the classic GHS transect in the central Himalaya, the upper and lower GHS in the Yadong region record different exhumation timing and rates affected by the Yadong fault activity, indicative of heterogeneous exhumation within the orogen. The AM method provides both mineral modes and compositions, which allow reconstruction of bulk-rock compositions on thin-section scales. The AM also facilitates recognition of accessory phases (e.g., zircons, titanite, rutile) for in situ analysis and dating.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"518 ","pages":"Article 108338"},"PeriodicalIF":2.5,"publicationDate":"2025-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145620228","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}
Pub Date : 2025-11-20DOI: 10.1016/j.lithos.2025.108339
İrfan Temizel , Mehmet Arslan , Sarah Sherlock
In this study, we investigate the petrology, age, whole-rock geochemistry, and Sr-Nd isotopic compositions of post-collisional andesitic suites from the İkizce and Ulubey (Ordu) areas of the Eastern Pontides Orogenic Belt (EPOB) to elucidate their magma source characteristics and the region's geodynamic evolution. The 40Ar-39Ar dating of the İkizce and Ulubey andesitic suites yielded cooling ages of ∼51–49 Ma and ∼ 49–46 Ma (Middle Eocene), respectively. Both İkizce and Ulubey andesite suites have adakitic geochemistry, displaying medium to high-K, high LaN/YbN (∼17.8–23.1 and 8.9–23.3, respectively) and Sr/Y (79–138 and 62–143, respectively) ratios. Besides, the adakitic suites show similar LREE-enriched and HREE-flattened patterns (LaN/LuN = 11.3–23.7 and 8.8–28.2, respectively) with insignificant Eu anomalies (EuN/Eu* =0.90–1.08 and 0.82–1.11, respectively). The İkizce and Ulubey adakitic suites have 87Sr/86Sr(i) (0.703861–0.703973 and 0.704347–0.704437), and 143Nd/144Nd(i) (0.512810–0.512846 and 0.512662–0.512748) with positive ɛNd(i) values (4.57–5.27 and 1.06–3.39), respectively. Combining the whole-rock geochemical and Sr-Nd isotope dataset of the studied adakitic andesitic suites suggests two different melt sources, whereby the İkizce adakitic suite was generated from slab-derived melts and the Ulubey adakitic suite originated from delaminated lower crust-derived melts, each of which also interacted with the lithospheric mantle components in a post-collisional tectonic setting during the Middle Eocene period.
{"title":"Post-collisional adakitic andesite suites originated from remnant slab- and delaminated lower crust-derived melts modified by mantle components: Constraints for petrogenesis of Cenozoic adakitic magmas in NE Türkiye","authors":"İrfan Temizel , Mehmet Arslan , Sarah Sherlock","doi":"10.1016/j.lithos.2025.108339","DOIUrl":"10.1016/j.lithos.2025.108339","url":null,"abstract":"<div><div>In this study, we investigate the petrology, age, whole-rock geochemistry, and Sr-Nd isotopic compositions of post-collisional andesitic suites from the İkizce and Ulubey (Ordu) areas of the Eastern Pontides Orogenic Belt (EPOB) to elucidate their magma source characteristics and the region's geodynamic evolution. The <sup>40</sup>Ar-<sup>39</sup>Ar dating of the İkizce and Ulubey andesitic suites yielded cooling ages of ∼51–49 Ma and ∼ 49–46 Ma (Middle Eocene), respectively. Both İkizce and Ulubey andesite suites have adakitic geochemistry, displaying medium to high-K, high La<sub>N</sub>/Yb<sub>N</sub> (∼17.8–23.1 and 8.9–23.3, respectively) and Sr/Y (79–138 and 62–143, respectively) ratios. Besides, the adakitic suites show similar LREE-enriched and HREE-flattened patterns (La<sub>N</sub>/Lu<sub>N</sub> = 11.3–23.7 and 8.8–28.2, respectively) with insignificant Eu anomalies (Eu<sub>N</sub>/Eu* =0.90–1.08 and 0.82–1.11, respectively). The İkizce and Ulubey adakitic suites have <sup>87</sup>Sr/<sup>86</sup>Sr<sub>(i)</sub> (0.703861–0.703973 and 0.704347–0.704437), and <sup>143</sup>Nd/<sup>144</sup>Nd<sub>(i)</sub> (0.512810–0.512846 and 0.512662–0.512748) with positive ɛNd<sub>(i)</sub> values (4.57–5.27 and 1.06–3.39), respectively. Combining the whole-rock geochemical and Sr-Nd isotope dataset of the studied adakitic andesitic suites suggests two different melt sources, whereby the İkizce adakitic suite was generated from slab-derived melts and the Ulubey adakitic suite originated from delaminated lower crust-derived melts, each of which also interacted with the lithospheric mantle components in a post-collisional tectonic setting during the Middle Eocene period.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"518 ","pages":"Article 108339"},"PeriodicalIF":2.5,"publicationDate":"2025-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145620229","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}
Pub Date : 2025-11-20DOI: 10.1016/j.lithos.2025.108337
Hang Yang , Jinlong Yao , Guochun Zhao , Yigui Han , Xiangsong Wang , Qiao Zhang
The southwestern South China Block experienced an intense tectono-thermal event during the Late Permian to Early Triassic, characterized by significant crustal shortening and the occurrence of massive peraluminous granites, granulites, charnockites, and minor mafic rocks. However, the orogenic mechanism of this event and the nature of the deep lithosphere remain enigmatic. Here, we report a ca. 249 Ma Huilong hornblende gabbro in the Yunkai massif, South China, and present comprehensive works of petrography, geochronology, mineral geochemistry, and isotopes, along with thermodynamic modeling. Geochemical data display IAB-like (island-arc basalts) chemical features with enrichment in large-ion lithophile elements (LILEs), light rare earth element (LREE), and Pb, but depletion in high field strength elements (HFSEs) relative to HREE. The chemical compositions (e.g., high ratios of La/Nb, Th/Yb) and negative zircon εHf(t) values (−11.0 to −9.7), along with Precambrian model ages, suggest that the gabbro was derived from partial melting of an ancient, enriched mantle source. Mineral thermobarometers and phase equilibria modeling indicate that the gabbroic magma evolved under water-rich (ca. 6.1 wt%), high-temperature (> 1100 °C), and low oxygen fugacity (ΔFMQ = −2.0 to −1.8) conditions. Combined with regional thermal anomalies, we suggest that the formation of the Huilong gabbro should have been related to the disturbance of the water-rich lithospheric mantle. The upwelling of the asthenosphere and subsequent basaltic magma underplating triggered partial melting of ancient metasomatized lithospheric mantle and crustal materials, resulting in the generation of these “arc-like” mafic rocks and massive anatectic granites, respectively. Moreover, multiple phases of Phanerozoic mafic suites within the Cathaysia block display consistent arc-like chemical signatures, enriched isotope compositions, and Precambrian model ages. These features suggest the presence of an ancient enriched subcontinental lithospheric mantle source beneath the Cathaysia, which had been modified by Precambrian subduction. Following the Late Permian to Triassic, the subduction of the Paleo-Pacific Plate triggered regional ∼NW-SE crustal shortening within the southwestern Cathaysia Block. Therefore, the Permo-Triassic tectono-magmatic event in Yunkai massif were likely associated with asthenosphere upwelling triggered by slab tearing/breakoff of the subducting Paleo-Pacific Plate.
{"title":"Permo-Triassic lithospheric reactivation in South China triggered by subduction of the Paleo-Pacific Plate: Constraints from hornblende gabbro in the Yunkai Massif","authors":"Hang Yang , Jinlong Yao , Guochun Zhao , Yigui Han , Xiangsong Wang , Qiao Zhang","doi":"10.1016/j.lithos.2025.108337","DOIUrl":"10.1016/j.lithos.2025.108337","url":null,"abstract":"<div><div>The southwestern South China Block experienced an intense tectono-thermal event during the Late Permian to Early Triassic, characterized by significant crustal shortening and the occurrence of massive peraluminous granites, granulites, charnockites, and minor mafic rocks. However, the orogenic mechanism of this event and the nature of the deep lithosphere remain enigmatic. Here, we report a ca. 249 Ma Huilong hornblende gabbro in the Yunkai massif, South China, and present comprehensive works of petrography, geochronology, mineral geochemistry, and isotopes, along with thermodynamic modeling. Geochemical data display IAB-like (island-arc basalts) chemical features with enrichment in large-ion lithophile elements (LILEs), light rare earth element (LREE), and Pb, but depletion in high field strength elements (HFSEs) relative to HREE. The chemical compositions (e.g., high ratios of La/Nb, Th/Yb) and negative zircon ε<sub>Hf</sub>(t) values (−11.0 to −9.7), along with Precambrian model ages, suggest that the gabbro was derived from partial melting of an ancient, enriched mantle source. Mineral thermobarometers and phase equilibria modeling indicate that the gabbroic magma evolved under water-rich (ca. 6.1 wt%), high-temperature (> 1100 °C), and low oxygen fugacity (ΔFMQ = −2.0 to −1.8) conditions. Combined with regional thermal anomalies, we suggest that the formation of the Huilong gabbro should have been related to the disturbance of the water-rich lithospheric mantle. The upwelling of the asthenosphere and subsequent basaltic magma underplating triggered partial melting of ancient metasomatized lithospheric mantle and crustal materials, resulting in the generation of these “arc-like” mafic rocks and massive anatectic granites, respectively. Moreover, multiple phases of Phanerozoic mafic suites within the Cathaysia block display consistent arc-like chemical signatures, enriched isotope compositions, and Precambrian model ages. These features suggest the presence of an ancient enriched subcontinental lithospheric mantle source beneath the Cathaysia, which had been modified by Precambrian subduction. Following the Late Permian to Triassic, the subduction of the Paleo-Pacific Plate triggered regional ∼NW-SE crustal shortening within the southwestern Cathaysia Block. Therefore, the Permo-Triassic tectono-magmatic event in Yunkai massif were likely associated with asthenosphere upwelling triggered by slab tearing/breakoff of the subducting Paleo-Pacific Plate.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"518 ","pages":"Article 108337"},"PeriodicalIF":2.5,"publicationDate":"2025-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145620097","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}
Pub Date : 2025-11-19DOI: 10.1016/j.lithos.2025.108332
Zhongzhou Li , Yijun Wang , Mengxi Wang , Ting Liang
<div><div>Development processes (construction and following solidification) of crystal mush have been considered as a fundamental issue for investigating the cooling process of layered intrusions. However, the magma processes related to the development of crystal mush and their roles are still enigmatic. In this study, we collected samples from the cyclic unit (CU) III in the upper part of Middle Zone (MZb) of the Wangjiangshan layered intrusion in Central China, in order to examine the development of crystal mush in a basaltic magma chamber. We carried out a comprehensive analysis on high-resolution elemental mapping, <em>in situ</em> major and trace elemental and Sr isotopic compositions for plagioclase of the CU III, which is mainly composed of olivine gabbro, oxide gabbro and minor biotite gabbro. Plagioclase crystals can be divided into five types based on distinct textures and compositions, <em>i.e.,</em> skeletal texture (Type 1), patchy zoning texture (Type 2), reverse zoning texture (Type 3), normal zoning texture (Type 4) and unzoned (Type 5). Type 1 plagioclase of olivine gabbro and biotite gabbro have skeletal cores in a boxy or geometric shape, indicating a moderate- to high-degree undercooling (−∆T = 30–70 °C) during cooling. Resorbed cores of Type 2 and some Type 3 plagioclase in olivine gabbro have high (<sup>87</sup>Sr/<sup>86</sup>Sr)<sub><em>i</em></sub> (0.70409–0.70428), indicating that they may crystallize from the boundary layers contaminated by country rocks at the roof of magma chamber and then be entrained downward to the bottom of main magma body by magma convection. Convective melts from the roof would travel downwards and then contact with the hotter main magma at the bottom, resulting in a moderate- to high-degree undercooling. Thus, we propose that magma convection is crucial for the rapid construction of crystal mush. The rims of Type 4 plagioclase in biotite gabbro have distinct lower (<sup>87</sup>Sr/<sup>86</sup>Sr)<sub><em>i</em></sub> (0.70337–0.70354) but higher REE (17.7–30.7 μg/g) than those for resorbed cores, suggesting that they may be formed by the replenishment of an evolved magma during solidification of crystal mush. Thus, the moderate- to high-degree undercooling of biotite gabbro may be ascribed to magma replenishment, which promotes the solidification of crystal mush. On the other hand, the solidification timescales of crystal mush in olivine gabbro and biotite gabbro are ∼ 6.1 kyr and ∼ 4.7 kyr, respectively, distinctly shorter than that of ∼ 15.4 kyr for oxide gabbro, indicating a rapid solidification of crystal mush by magma convection and replenishment. In contrast, the absence of Type 1 to Type 3 plagioclase in oxide gabbro indicates the stagnation of magma convection and absence of magma replenishment, resulting in a decrease of undercooling degree and a slow construction and solidification of crystal mush. Furthermore, the invariable An for rims of some Type 1 to Type 4 plagioclase in olivi
{"title":"The development process of crystal mush in mafic magma chambers: Insights from the texture and composition of plagioclase in the Wangjiangshan layered intrusion, Central China","authors":"Zhongzhou Li , Yijun Wang , Mengxi Wang , Ting Liang","doi":"10.1016/j.lithos.2025.108332","DOIUrl":"10.1016/j.lithos.2025.108332","url":null,"abstract":"<div><div>Development processes (construction and following solidification) of crystal mush have been considered as a fundamental issue for investigating the cooling process of layered intrusions. However, the magma processes related to the development of crystal mush and their roles are still enigmatic. In this study, we collected samples from the cyclic unit (CU) III in the upper part of Middle Zone (MZb) of the Wangjiangshan layered intrusion in Central China, in order to examine the development of crystal mush in a basaltic magma chamber. We carried out a comprehensive analysis on high-resolution elemental mapping, <em>in situ</em> major and trace elemental and Sr isotopic compositions for plagioclase of the CU III, which is mainly composed of olivine gabbro, oxide gabbro and minor biotite gabbro. Plagioclase crystals can be divided into five types based on distinct textures and compositions, <em>i.e.,</em> skeletal texture (Type 1), patchy zoning texture (Type 2), reverse zoning texture (Type 3), normal zoning texture (Type 4) and unzoned (Type 5). Type 1 plagioclase of olivine gabbro and biotite gabbro have skeletal cores in a boxy or geometric shape, indicating a moderate- to high-degree undercooling (−∆T = 30–70 °C) during cooling. Resorbed cores of Type 2 and some Type 3 plagioclase in olivine gabbro have high (<sup>87</sup>Sr/<sup>86</sup>Sr)<sub><em>i</em></sub> (0.70409–0.70428), indicating that they may crystallize from the boundary layers contaminated by country rocks at the roof of magma chamber and then be entrained downward to the bottom of main magma body by magma convection. Convective melts from the roof would travel downwards and then contact with the hotter main magma at the bottom, resulting in a moderate- to high-degree undercooling. Thus, we propose that magma convection is crucial for the rapid construction of crystal mush. The rims of Type 4 plagioclase in biotite gabbro have distinct lower (<sup>87</sup>Sr/<sup>86</sup>Sr)<sub><em>i</em></sub> (0.70337–0.70354) but higher REE (17.7–30.7 μg/g) than those for resorbed cores, suggesting that they may be formed by the replenishment of an evolved magma during solidification of crystal mush. Thus, the moderate- to high-degree undercooling of biotite gabbro may be ascribed to magma replenishment, which promotes the solidification of crystal mush. On the other hand, the solidification timescales of crystal mush in olivine gabbro and biotite gabbro are ∼ 6.1 kyr and ∼ 4.7 kyr, respectively, distinctly shorter than that of ∼ 15.4 kyr for oxide gabbro, indicating a rapid solidification of crystal mush by magma convection and replenishment. In contrast, the absence of Type 1 to Type 3 plagioclase in oxide gabbro indicates the stagnation of magma convection and absence of magma replenishment, resulting in a decrease of undercooling degree and a slow construction and solidification of crystal mush. Furthermore, the invariable An for rims of some Type 1 to Type 4 plagioclase in olivi","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"518 ","pages":"Article 108332"},"PeriodicalIF":2.5,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145620227","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}
The Sonapahar granite gneiss within the Meghalaya Gneissic Complex of northeastern India provides a rare record of Mesoproterozoic low-δ18O A-type felsic magmatism formed by partial melting of a hydrothermally altered lower crust. Field relationships reveal that the Sonapahar granite gneiss occurs as concordant, lensoidal bodies in gradational contact with surrounding metapelites, suggesting a genetic link to the melt source. Microstructural features, including aligned oxide-rich bands, poikilitic texture, and interstitial quartz, indicate in situ melt generation under high-temperature, fluid-absent granulite-facies conditions. SIMS UPb dating of zircons yields a crystallization age of 1629 ± 5.2 Ma, synchronous with regional granulite metamorphism. Concordant domains within zircons preserve low δ18O values (3.1 ‰ to 4.8 ‰), suggesting anatexis of a metapelitic protolith that had been previously altered by 18O-depleted fluids. Field and map relationships suggest generation of ∼15 % partial melting, and trace element modeling supports derivation from fertile cordierite gneiss with elevated Zr, Th, and Y contents. These isotopic data collectively indicate the intracrustal reworking of isotopically modified crust under high heat flow, likely associated with post-orogenic tectonothermal activity during the evolution of the Columbia supercontinent. Comparisons with low-δ18O systems from the Talbot sub-basin, Australia, and North Dabie, China, highlight the broader significance of the Sonapahar granite gneiss in preserving deep crustal isotopic signatures in high-grade metamorphic terrane.
{"title":"In situ melting of hydrothermally altered crust in the Meghalaya Gneissic Complex, India: A Mesoproterozoic record of low-δ18O felsic magmatism","authors":"Susobhan Neogi , Ritesh Kumar Mishra , Tapan Pal , Sandip Nandy","doi":"10.1016/j.lithos.2025.108324","DOIUrl":"10.1016/j.lithos.2025.108324","url":null,"abstract":"<div><div>The Sonapahar granite gneiss within the Meghalaya Gneissic Complex of northeastern India provides a rare record of Mesoproterozoic low-δ<sup>18</sup>O A-type felsic magmatism formed by partial melting of a hydrothermally altered lower crust. Field relationships reveal that the Sonapahar granite gneiss occurs as concordant, lensoidal bodies in gradational contact with surrounding metapelites, suggesting a genetic link to the melt source. Microstructural features, including aligned oxide-rich bands, poikilitic texture, and interstitial quartz, indicate in situ melt generation under high-temperature, fluid-absent granulite-facies conditions. SIMS U<img>Pb dating of zircons yields a crystallization age of 1629 ± 5.2 Ma, synchronous with regional granulite metamorphism. Concordant domains within zircons preserve low δ<sup>18</sup>O values (3.1 ‰ to 4.8 ‰), suggesting anatexis of a metapelitic protolith that had been previously altered by <sup>18</sup>O-depleted fluids. Field and map relationships suggest generation of ∼15 % partial melting, and trace element modeling supports derivation from fertile cordierite gneiss with elevated Zr, Th, and Y contents. These isotopic data collectively indicate the intracrustal reworking of isotopically modified crust under high heat flow, likely associated with post-orogenic tectonothermal activity during the evolution of the Columbia supercontinent. Comparisons with low-δ<sup>18</sup>O systems from the Talbot sub-basin, Australia, and North Dabie, China, highlight the broader significance of the Sonapahar granite gneiss in preserving deep crustal isotopic signatures in high-grade metamorphic terrane.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"518 ","pages":"Article 108324"},"PeriodicalIF":2.5,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145576648","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}
Pub Date : 2025-11-19DOI: 10.1016/j.lithos.2025.108331
L.M. Saper , G. Bromiley , R. Cao , M. Brounce , E.C. Hughes , D. Woelki
Sulfur cycling in the vicinity of subduction zones is an important control on chalcophile element mobility and the formation of massive sulfide ore deposits such as those exposed in the Cretaceous-aged Troodos Ophiolite in Cyprus. Here, we assess the sources and fates of magmatic S in the Troodos Ophiolite using in-situ S isotope measurements of quenched volcanic glasses along with petrographic and geochemical evidence for sulfide saturation in both primitive and evolved melts. Primitive glasses (MgO ≥ 8 wt%) define the primary S isotope composition of the ophiolite: δ34S = +0.14 ± 0.56 ‰ (1 s.d., V-CDT, n = 12), which overlaps with mid-ocean ridge basalts and is low compared to bulk δ34S values measured in altered rocks and sulfide ore deposits in the ophiolite that interacted with 34S-enriched seawater. The Troodos glasses have geochemical and isotopic evidence for slab influence, however these parameters (e.g., H2O, oxygen fugacity, Ba/La, 87Sr/86Sr) do not correlate with δ34S values, suggesting that the flux of slab-derived S was low. Magmatic pyrrhotite inclusions in Mg-rich olivine and chromite phenocrysts indicate that some primitive Troodos mantle melts were reduced and saturated with an immiscible Ni-rich sulfide liquid. During ascent, melt aggregation and decompression resulted in sulfide-undersaturation and a wide range of dissolved S contents in lavas. The S contents of lavas require a heterogeneous mantle source and cannot be explained solely by magmatic S degassing. In evolved magmas, saturation of Cu-rich sulfide accompanied exsolution of a fluid phase and Fe–Ti oxide saturation, and in some cases this may have occurred during rapid cooling upon eruption at the seafloor. Collectively, these observations confirm that magmatic S in the Troodos Ophiolite was derived from a reduced, depleted and variably sulfide-saturated mantle and that slab fluids involved in flux melting were sulfur-poor.
俯冲带附近的硫循环是亲铜元素流动和块状硫化物矿床形成的重要控制因素，如塞浦路斯白垩纪Troodos蛇绿岩中暴露的硫化物矿床。本文利用淬火火山玻璃的原位S同位素测量以及原始和演化熔体硫化物饱和度的岩石学和地球化学证据，评估了Troodos蛇绿岩中岩浆S的来源和流向。原始玻璃（MgO≥8 wt%）定义了蛇绿岩的主要S同位素组成：δ34S = +0.14±0.56‰（1 s.d, V-CDT, n = 12），与洋中脊玄武岩重叠，与蛇绿岩中蚀变岩和硫化物矿床测量的整体δ34S值相比较低，蛇绿岩与富34s海水相互作用。Troodos玻璃具有板坯影响的地球化学和同位素证据，但这些参数（如H2O、氧度、Ba/La、87Sr/86Sr）与δ34S值无关，表明板坯衍生S的通量很低。富镁橄榄石和铬铁矿斑晶中的岩浆磁黄铁矿包裹体表明，一些原始的Troodos地幔熔体被还原并被不混溶的富镍硫化物液体饱和。在上升过程中，熔体聚集和减压导致熔岩硫化物欠饱和，溶解S含量范围较大。熔岩的S含量需要非均质地幔源，不能仅仅用岩浆S脱气来解释。在演化的岩浆中，富cu硫化物的饱和伴随着流体相的析出和Fe-Ti氧化物的饱和，在某些情况下，这可能发生在海底喷发后的快速冷却过程中。总的来说，这些观察结果证实，Troodos蛇绿岩中的岩浆S来自一个还原的、耗尽的、硫化物饱和的地幔，而参与熔剂熔化的板块流体是缺硫的。
{"title":"The primary magmatic δ34S of the Troodos Ophiolite and evidence for early and late sulfide saturation","authors":"L.M. Saper , G. Bromiley , R. Cao , M. Brounce , E.C. Hughes , D. Woelki","doi":"10.1016/j.lithos.2025.108331","DOIUrl":"10.1016/j.lithos.2025.108331","url":null,"abstract":"<div><div>Sulfur cycling in the vicinity of subduction zones is an important control on chalcophile element mobility and the formation of massive sulfide ore deposits such as those exposed in the Cretaceous-aged Troodos Ophiolite in Cyprus. Here, we assess the sources and fates of magmatic S in the Troodos Ophiolite using in-situ S isotope measurements of quenched volcanic glasses along with petrographic and geochemical evidence for sulfide saturation in both primitive and evolved melts. Primitive glasses (MgO ≥ 8 wt%) define the primary S isotope composition of the ophiolite: δ<sup>34</sup>S = +0.14 ± 0.56 ‰ (1 s.d., V-CDT, <em>n</em> = 12), which overlaps with mid-ocean ridge basalts and is low compared to bulk δ<sup>34</sup>S values measured in altered rocks and sulfide ore deposits in the ophiolite that interacted with <sup>34</sup>S-enriched seawater. The Troodos glasses have geochemical and isotopic evidence for slab influence, however these parameters (e.g., H<sub>2</sub>O, oxygen fugacity, Ba/La, <sup>87</sup>Sr/<sup>86</sup>Sr) do not correlate with δ<sup>34</sup>S values, suggesting that the flux of slab-derived S was low. Magmatic pyrrhotite inclusions in Mg-rich olivine and chromite phenocrysts indicate that some primitive Troodos mantle melts were reduced and saturated with an immiscible Ni-rich sulfide liquid. During ascent, melt aggregation and decompression resulted in sulfide-undersaturation and a wide range of dissolved S contents in lavas. The S contents of lavas require a heterogeneous mantle source and cannot be explained solely by magmatic S degassing. In evolved magmas, saturation of Cu-rich sulfide accompanied exsolution of a fluid phase and Fe–Ti oxide saturation, and in some cases this may have occurred during rapid cooling upon eruption at the seafloor. Collectively, these observations confirm that magmatic S in the Troodos Ophiolite was derived from a reduced, depleted and variably sulfide-saturated mantle and that slab fluids involved in flux melting were sulfur-poor.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"518 ","pages":"Article 108331"},"PeriodicalIF":2.5,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145576653","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}
Pub Date : 2025-11-19DOI: 10.1016/j.lithos.2025.108334
Ao Li , Wu-Bin Yang , Xu Zhao , He-Cai Niu , Ning-Bo Li , Pan Qu
The recycling of subducted oceanic slabs via dehydration and melting drives the transfer of materials from the oceanic crust to overlying continental crust. This process has been well-recognized in arc and intraplate volcanic rocks. However, its role in generating intraplate granitic magmas, the major components of Earth's continental crust, remains poorly constrained. In this study, we utilized multiple isotopic systems, including whole-rock Nd-Pb-Mg and zircon O-Hf isotopes, to investigate the Early Cretaceous Jiajiagou (130.5 ± 1.0 Ma) and Yangjinggou (128.5 ± 1.0 Ma) granites in NE China. The whole-rock geochemical signatures suggest that these are highly fractionated I-type granites, with compositional variations governed mainly by plagioclase and alkali feldspar fractionation. These rocks have positive εNd(t) values (Jiajiagou: 2.35–2.73; Yangjinggou: 1.76–2.35) and young two-stage Nd model ages (< 1.0 Ga), indicative of a juvenile crustal source. Zircon O-Hf isotopic analyses yielded sub-mantle δ18O values (Jiajiagou: 3.43 ‰ – 5.13 ‰; Yangjinggou: 2.28 ‰ – 5.12 ‰) and positive εHf(t) values (Jiajiagou: 4.70–13.4; Yangjinggou: 2.37–11.1), indicating contributions from high-temperature hydrothermally altered oceanic crust and an enriched mantle component to their juvenile crustal source. This inference is further supported by the whole-rock Mg isotopic compositions (δ26Mg = −0.32 ‰ to −0.02 ‰), which fall within the range of high-temperature hydrothermally altered oceanic crust. Such altered oceanic crust likely represents remnants that were previously trapped beneath the lithosphere, detached from Paleozoic to Mesozoic subducted oceanic slabs. Considering the Nd-Pb isotopic similarities with local Late Jurassic basalts, the granites are interpreted to have formed in two stages: (1) the generation of a juvenile crustal source, possibly produced by the underplating of basaltic magmas originating from the mixing of high-temperature hydrothermally altered oceanic crust with an enriched mantle component; and (2) the formation of parental magmas through partial melting of this juvenile crustal source, followed by fractional crystallization. Consequently, our findings highlight that recycled oceanic crust is a potentially significant source component for Phanerozoic highly fractionated I-type granites across NE China. This recycling mechanism, operating in tandem with contributions from enriched mantle reservoirs, represents a fundamental process of continental crustal growth in this region.
{"title":"O-Hf-Mg isotopic signals of recycled oceanic crust in the Early Cretaceous I-type granites from NE China","authors":"Ao Li , Wu-Bin Yang , Xu Zhao , He-Cai Niu , Ning-Bo Li , Pan Qu","doi":"10.1016/j.lithos.2025.108334","DOIUrl":"10.1016/j.lithos.2025.108334","url":null,"abstract":"<div><div>The recycling of subducted oceanic slabs via dehydration and melting drives the transfer of materials from the oceanic crust to overlying continental crust. This process has been well-recognized in arc and intraplate volcanic rocks. However, its role in generating intraplate granitic magmas, the major components of Earth's continental crust, remains poorly constrained. In this study, we utilized multiple isotopic systems, including whole-rock Nd-Pb-Mg and zircon O-Hf isotopes, to investigate the Early Cretaceous Jiajiagou (130.5 ± 1.0 Ma) and Yangjinggou (128.5 ± 1.0 Ma) granites in NE China. The whole-rock geochemical signatures suggest that these are highly fractionated I-type granites, with compositional variations governed mainly by plagioclase and alkali feldspar fractionation. These rocks have positive ε<sub>Nd</sub>(t) values (Jiajiagou: 2.35–2.73; Yangjinggou: 1.76–2.35) and young two-stage Nd model ages (< 1.0 Ga), indicative of a juvenile crustal source. Zircon O-Hf isotopic analyses yielded sub-mantle δ<sup>18</sup>O values (Jiajiagou: 3.43 ‰ – 5.13 ‰; Yangjinggou: 2.28 ‰ – 5.12 ‰) and positive ε<sub>Hf</sub>(t) values (Jiajiagou: 4.70–13.4; Yangjinggou: 2.37–11.1), indicating contributions from high-temperature hydrothermally altered oceanic crust and an enriched mantle component to their juvenile crustal source. This inference is further supported by the whole-rock Mg isotopic compositions (δ<sup>26</sup>Mg = −0.32 ‰ to −0.02 ‰), which fall within the range of high-temperature hydrothermally altered oceanic crust. Such altered oceanic crust likely represents remnants that were previously trapped beneath the lithosphere, detached from Paleozoic to Mesozoic subducted oceanic slabs. Considering the Nd-Pb isotopic similarities with local Late Jurassic basalts, the granites are interpreted to have formed in two stages: (1) the generation of a juvenile crustal source, possibly produced by the underplating of basaltic magmas originating from the mixing of high-temperature hydrothermally altered oceanic crust with an enriched mantle component; and (2) the formation of parental magmas through partial melting of this juvenile crustal source, followed by fractional crystallization. Consequently, our findings highlight that recycled oceanic crust is a potentially significant source component for Phanerozoic highly fractionated I-type granites across NE China. This recycling mechanism, operating in tandem with contributions from enriched mantle reservoirs, represents a fundamental process of continental crustal growth in this region.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"518 ","pages":"Article 108334"},"PeriodicalIF":2.5,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145620096","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}
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