Precambrian Research最新文献

{"title":"Detrital apatite records 1.9–1.8 Ga orogenesis in ‘tectono-thermal-event-poor’ region of southern margin of the North China craton","authors":"Fengbo Sun ,&nbsp;Peng Peng ,&nbsp;Deshun Zheng ,&nbsp;Boyang Xu","doi":"10.1016/j.precamres.2026.108037","DOIUrl":"10.1016/j.precamres.2026.108037","url":null,"abstract":"<div><div>The late Paleoproterozoic Trans-North China Orogen (TNCO) records the amalgamation of the Western and Eastern blocks of the North China Craton (NCC). As a “tectono-thermal-event-poor” segment within the southern TNCO, the Wangwu-Zhongtiao Mountains region serves as a critical focus for tectonic investigations. Given that sediments are integrated archives of provenance lithologies, here we utilize U-Pb geochronology and trace and rare earth element geochemistry (TREE) of detrital apatite and zircon from clastic rocks of the Paleoproterozoic Dagushi Formation to constrain the evolutionary history of their source regions. This formation is the first fluvial-lacustrine system in the study area since the Paleoproterozoic orogenesis in the NCC. Analyses indicate that the 2.7–1.9 Ga zircon grains with multiple peaks inside the formation were from the nearby or proximal Archean-Paleoproterozoic basement; yet they show few coeval apatites. While the newly reported younger 1.9–1.8 Ga U-Pb ages of detrital apatite are abundant in the clastic rocks. Based on their TREE signatures (e.g.<em>,</em> LREE enrichment, Sr depletion), as well as the fact of lacking contemporaneous zircon ages from the same samples, it provides critical insights into the geology of low- to high-grade metamorphic events of the Wangwu-Zhongtiao Mountains region. Three distinct metamorphic stages respectively at 1940–1930 Ma, 1890–1860 Ma, and 1840–1810 Ma can be differentiated, demonstrating that the late Paleoproterozoic tectono-thermal events in the Wangwu-Zhongtiao Mountains region are synchronous with those in the central and northern parts of the TNCO. The minor population of detrital apatite grains with ages of ca. 1770 Ma and younger grains may reflect the overprinting or alteration by post-orogenic thermal events. These events could potentially be linked to thermal effects associated with the volcanism of the Xiong’er Group, and 1.8–1.6 Ga anorogenic magmatism in the southern NCC. This study thus provides an indirect methodological framework for deciphering tectono-thermal events in less exposed/preserved regions.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"435 ","pages":"Article 108037"},"PeriodicalIF":3.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174435","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":"Corrigendum to “A window on the amalgamation of Western Gondwana: Geological history of the Ouaddaï massif (E. Chad)”. [Precam. Res. 434 (2026) 108000]","authors":"Alexis Plunder ,&nbsp;Olivier Blein ,&nbsp;Moussa Isseini ,&nbsp;Issaka Ousman Al-Gadam ,&nbsp;Mathieu Chevillard ,&nbsp;Emanuel Djedouboum ,&nbsp;Philippe Lach ,&nbsp;Abdeltif Lahfid ,&nbsp;Jérémie Melleton ,&nbsp;Olivier Rouzeau ,&nbsp;Guillaume Vic","doi":"10.1016/j.precamres.2026.108017","DOIUrl":"10.1016/j.precamres.2026.108017","url":null,"abstract":"","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"435 ","pages":"Article 108017"},"PeriodicalIF":3.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174461","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":"A window on the amalgamation of Western Gondwana: Geological history of the Ouaddaï massif (E. Chad)","authors":"Alexis Plunder ,&nbsp;Olivier Blein ,&nbsp;Moussa Isseini ,&nbsp;Issaka Ousman Al-Gadam ,&nbsp;Matthieu Chevillard ,&nbsp;Emanuel Djedouboum ,&nbsp;Philippe Lach ,&nbsp;Abdeltif Lahfid ,&nbsp;Jérémie Melleton ,&nbsp;Olivier Rouzeau ,&nbsp;Guillaume Vic","doi":"10.1016/j.precamres.2025.108000","DOIUrl":"10.1016/j.precamres.2025.108000","url":null,"abstract":"<div><div>The Saharan metacraton was assembled during pre-Neoproterozoic to Neoproterozoic times and was strongly remobilised during the Pan African orogeny. The Ouaddaï massif in eastern Chad represents the core of the Saharan metacraton, yet its geological history remains poorly documented. In this study, we combine of field observations, petrological analysis of metamorphic rocks, and geochemical and geochronological constraints to reconstruct the tectono-metamorphic evolution of the Ouaddaï massif. The study area is dominated by collision-related plutonic rocks and migmatitic gneisses, within which inliers of older basement occur. Geochemical data indicate a transition from active-margin to collisional magmatism, with a compositional evolution from diorite to granite. This suite is cross-cut by syenogranites and alkaline granites with shoshonitic affinities, interpreted as post-collisional granitoids derived from tonalitic rocks to sedimentary protoliths. Geochronological data (U-Pb on zircon and monazite) point to a ca. 1000 Ma age for orthogneisses inliers. Granitoids of the Ouaddaï massif record emplacement ages from 620 to 590 Ma, coeval with high-temperature metamorphism characterized by peak pressure–temperature conditions of 1.2 GPa and 850 °C (mafic granulite) and around 0.8 GPa and 700 °C (sillimanite-garnet bearing migmatites). Integrating our new results with regional data, we discuss the existence and geodynamic evolution of the Saharan Metacraton. Our findings emphasize the significance of the Saharan Metacraton as a key region for understanding the extensive reworking of cratonic lithosphere during both a Tonian magmatic phase prior and the assembly of Gondwana.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"434 ","pages":"Article 108000"},"PeriodicalIF":3.2,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145927927","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":"New occurrence of a postglacial Ediacaran macrofossil assemblage from North China and its evolutionary implication","authors":"Xin Wang ,&nbsp;Xingliang Zhang ,&nbsp;Tao Dai ,&nbsp;Wei Liu ,&nbsp;Yuan Zhang ,&nbsp;Luoyang Li","doi":"10.1016/j.precamres.2025.107992","DOIUrl":"10.1016/j.precamres.2025.107992","url":null,"abstract":"<div><div>The late Ediacaran witnessed a significant evolutionary junction, characterized by a pronounced decline in the diversity of Ediacara-type macrofossils and macroalgae, coinciding with the expansion of tubular organisms and mobile bilaterians as evidenced by trace fossils. The North China Craton (NCC), one of the oldest cratons with a geological history spanning more than 3.8 billion years, contains extensively distributed Ediacaran deposits along its western and southern margins. However, the Ediacaran fossil assemblages in NCC remain poorly understood, particularly due to the absence of Ediacara-type fossils. Here, we report a newly discovered macrofossil assemblage, the Dongpo biota (ca. 550–538.8 Ma), from the terminal Ediacaran Dongpo Formation, a shale-dominated sequence exposed along the southern margin of NCC. The biota comprises a diverse assemblage that includes frondose fossils, macroalgae, tubular forms, bilaterian trace fossils, and various problematic fossils, demonstrating a clear stratigraphic overlap. The new biota expands the known paleogeographic distribution of the Ediacaran macrofossils and offers crucial evidence enhancing our understanding of biotic communities inhabiting siliciclastic-dominated seafloors during the terminal Ediacaran period. Moreover, the fossil-bearing horizon conformably overlies the Luoquan diamictite, indicating that the Dongpo biota represents a postglacial Ediacaran macrofossil assemblage. Thus, this new biota provides key insights into the recovery and flourishing of benthic marine ecosystems after the ‘Great Ediacaran Glaciation’.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"434 ","pages":"Article 107992"},"PeriodicalIF":3.2,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145886104","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":"Marine evaporitic borate mineralization during the Lomagundi–Jatuli Event, Liaodong Peninsula, northeast China","authors":"Guyue Hu ,&nbsp;Chunlian Wang ,&nbsp;Kuidong Zhao ,&nbsp;Qian Li ,&nbsp;Yanhe Li ,&nbsp;Xinsheng Sun ,&nbsp;Jun Zheng ,&nbsp;Kunming Wang ,&nbsp;Jianghua Gong ,&nbsp;Peng Li ,&nbsp;Yue Zhao","doi":"10.1016/j.precamres.2025.107998","DOIUrl":"10.1016/j.precamres.2025.107998","url":null,"abstract":"<div><div>Many Paleoproterozoic borate deposits are hosted within the lower units of the volcanic–sedimentary sequence (<em>ca</em>. 2.2 Ga) of the Liaohe Group, Liaodong Peninsula, northeast China. It is debated as to whether these deposits were affected by marine evaporation. The borate ore bodies of the Zhuanmiao deposit in the Liaohe Group have stratiform or lenticular shapes and occur in serpentinized carbonates, with the ores being bordered by layered leptynites, leptites, amphibolites, and migmatites. We carried out a C–O–Mg stable isotope study of the ores and carbonate rocks in the Zhuanmiao deposit. The <em>δ</em>¹³C values of unserpentinized magnesite marbles in the ores of the Errengou block in the Zhuanmiao deposit range from +3.2 ‰ to +6.0 ‰ and preserve a positive C isotopic anomaly typical of the Lomagundi–Jatuli Event (2.306–2.057 Ga). The <em>δ</em>²⁶Mg values of these unserpentinized magnesite marbles in the Zhuanmiao borate deposit range from –1.01 ‰ to –0.84 ‰, which are typical of marine sediments. The positive C isotopic anomaly of the magnesite marbles in the Zhuanmiao deposit indicates that the C isotopic anomaly of magnesite that formed during the Lomagundi–Jatuli Event is not only a result of global oxygenation of the ocean–atmosphere, but also marine evaporation in individual basins. This evaporation even led to rare examples of borate mineralization.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"434 ","pages":"Article 107998"},"PeriodicalIF":3.2,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145852427","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":"Crustal structure in the Quadrilátero Ferrífero mineral province, SE Brazil: differentiating preserved and reworked Archean crust","authors":"Taghi Shirzad ,&nbsp;Marcelo Assumpção ,&nbsp;Marcelo B. Bianchi ,&nbsp;Bruno Collaço ,&nbsp;Fernando Alkmim ,&nbsp;Dionísio U. Carlos ,&nbsp;Luciano Assis ,&nbsp;Maximiliano Simão","doi":"10.1016/j.precamres.2025.108003","DOIUrl":"10.1016/j.precamres.2025.108003","url":null,"abstract":"<div><div>The <em>Quadrilátero Ferrífero</em> (QF; Iron Quadrangle) on the southeastern São Francisco craton exposes Paleoarchean to Paleoproterozoic rocks shaped by multiple Precambrian tectonic events. Despite extensive mapping, its deeper crustal structure remains poorly constrained, limiting insights into Archean stabilization and later Paleoproterozoic reworking. Clarifying whether the QF greenstone belt preserves Mesoarchean lithosphere or later modification is key to understanding the region’s tectonic evolution. The deeper crustal structure also informs mineral potential, as crustal architecture governs ore localization in stable cratons. Here we study the deep crustal structure using teleseismic receiver functions (RF), recorded at six stations of the VALE QF seismic network, together with Rayleigh and Love wave dispersion curves. We retrieved group velocities of Rayleigh and Love waves from ambient noise of local and regional stations between 0.3 and 4.4 s, sampling the upper crust. For longer periods (5 to 100 s), we used group and phase velocities of continental-scale tomography models. Joint inversion of receiver functions and surface-wave dispersion curves showed a thin crust (∼35 km) in the middle of the QF province, beneath the Rio das Velhas greenstone belt, and a thicker crust (∼42 km) in the eastern and western areas of the QF. The variations of crustal thickness resulting from the joint inversion are consistent with <em>H-k</em> stacking of receiver functions. Other stations in the São Francisco craton, outside the QF, show intermediate thicknesses of 36–39 km. Bulk crustal <em>Vp/</em>Vs ranged from 1.72 to 1.74, with no systematic variation across the QF. The QF central area, beneath the Rio das Velhas greenstone belt, has thin crust and normal S-wave velocities in the lower crust Vs (3.8–3.9 km/s) consistent with intermediate granulite composition, whereas the stations with thick crust, on either side of the central greenstone belt, show high Vs (∼3.9–4.1 km/s) in the lowermost crust suggesting a more mafic composition. This contrast in the lower crust properties can be interpreted as preservation of the stabilized Mesoarchean crust beneath the greenstone belt. Alternatively, the crust in the middle of the QF could have been thinned during the extensional collapse at the end of the Minas orogeny in the Paleoproterozoic.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"434 ","pages":"Article 108003"},"PeriodicalIF":3.2,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145886107","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":"Corrigendum to “Eoarchean low δ18O zircon indicates emergent land at 3.73 Ga” [Precambrian Res. 408 (2024) 107416]","authors":"Piotr Król ,&nbsp;Monika A. Kusiak ,&nbsp;Martin J. Whitehouse ,&nbsp;Daniel J. Dunkley ,&nbsp;Simon A. Wilde","doi":"10.1016/j.precamres.2026.108014","DOIUrl":"10.1016/j.precamres.2026.108014","url":null,"abstract":"","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"434 ","pages":"Article 108014"},"PeriodicalIF":3.2,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146023580","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":"Identification of eclogites that record Palaeoproterozoic and Triassic metamorphism in the Dabie UHP orogenic belt, eastern-central China","authors":"Jianhui Liu ,&nbsp;Wei Jin ,&nbsp;Fulai Liu ,&nbsp;Zhengjiang Ding ,&nbsp;Yuanshuo Li ,&nbsp;Weinan Xu","doi":"10.1016/j.precamres.2025.107990","DOIUrl":"10.1016/j.precamres.2025.107990","url":null,"abstract":"<div><div>In this study, zircon U–Th–Pb dating coupled with zircon morphology and texture observations, and trace element and Hf isotope analyses conducted on ultrahigh-pressure (UHP) eclogites and the host granitic gneiss in the central Dabie UHP belt has identified Neoarchean (ca. 2.5 Ga), Palaeoproterozoic (ca. 1.9 Ga) metamorphic events and Triassic UHP metamorphism at ca. 236 Ma. The Palaeoproterozoic metamorphic zircons from two eclogite samples and one granitic gneiss sample have consistent weighted mean ages of 1871 ± 26, 1890 ± 15, and 1915 ± 41 Ma, respectively. They exhibit low Th/U ratios (mostly &lt; 0.1), depletions in light rare earth elements (LREE) and enrichments in heavy rare earth elements (HREE) characterized by steep chondrite-normalized patterns, and yielded a large range of Ti-in-zircon temperatures varying from 892 ℃ to 642 ℃, indicating their metamorphic recrystallization or growth under wide metamorphic condition. The Palaeoproterozoic metamorphic zircons from the eclogites have mostly uniform Hf compositions and positive ε_Hf(t) values distinctly different from the Palaeoproterozoic metamorphic zircons with variable Hf compositions and negative ε_Hf(t) values from the host granitic gneiss. The Triassic metamorphic zircons from two eclogite samples and one granitic gneiss sample gave weighted-mean ages of 236 ± 2, 236 ± 1 and 234 ± 3 Ma, respectively. They exhibit low Th/U ratios (mostly &lt; 0.1), depletions in LREE and distinctively flat chondrite-normalized HREE patterns, and mostly consistent Hf isotope compositions with extremely low ¹⁷⁶Lu/¹⁷⁷Hf ratios and negative ε_Hf(t) values, and yielded Ti-in-zircon temperature of ca. 724℃ consistent with Triassic UHP metamorphic temperature, thus, these zircons is interpreted to be formed under Triassic UHP metamorphism. The host granitic gneiss has a minimum estimate of magmatic crystallization age of 2723 Ma. Therefore, it can be concluded that mafic protolith of the eclogite and the host granitic gneiss together experienced Palaeoproterozoic metamorphism at ca. 1.9 Ga and then Triassic UHP metamorphism at ca. 236 Ma. Additionally, it has further been suggested that the Early Precambrian basement exists and was involved in Triassic UHP metamorphism in the central Dabie UHP belt.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"433 ","pages":"Article 107990"},"PeriodicalIF":3.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145749410","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":"South China in the Rodinia-Gondwana transition: Constrains from the Ediacaran Doushantuo Formation of the north Yangtze Block","authors":"Lisha Hu ,&nbsp;Jie Yang ,&nbsp;Yuansheng Du ,&nbsp;Zuozhen Han ,&nbsp;Hongwei Kuang ,&nbsp;Yongqing Liu ,&nbsp;Chao Han ,&nbsp;Yi Zhang ,&nbsp;Wei Jin ,&nbsp;Le Wan","doi":"10.1016/j.precamres.2025.107996","DOIUrl":"10.1016/j.precamres.2025.107996","url":null,"abstract":"<div><div>The paleogeographic position of South China and its tectonic affinity with other continental blocks during the Rodinia-Gondwana transition remain not well established. This study reports new zircon U-Pb ages and Lu-Hf isotopic data from the Ediacaran Doushantuo Formation in the Chengkou-Zhenba area on the northern margin of the Yangtze Block. Detrital zircons yield concordant ages ranging from 2654 to 596 Ma, with 95 % of the grains clustering in the range of 1066 and 596 Ma. The age spectrum exhibits two major peaks at 633 Ma and 609 Ma, along with three minor peaks at 893 Ma, 851 Ma, and 749 Ma. The ε_Hf(t) values are predominantly positive, with 92 % of the analyses ranging from + 1.1 to + 13.6. The detrital zircon age distribution of the Doushantuo Formation is largely consistent with that of magmatic rocks from the Panxi-Hannan belt, supplemented by an additional Pan-African age population (ca. 630–600 Ma). Integrated U-Pb–Hf isotopic provenance analysis of Neoproterozoic rocks from the north Yangtze Block suggests that, aside from the ca. 630–600 Ma detritus, most detrital zircons were likely derived from nearby magmatic rocks in the Panxi-Hannan belt of the north Yangtze Block. Qualitative comparisons of detrital zircon age distributions between our samples and contemporaneous Ediacaran sedimentary strata in South China and other continental blocks indicate that the ca. 630–600 Ma detritus likely originated from Pan-African orogens in northern Gondwana, particularly the East African Orogen in southern India. These findings support a close paleogeographic and tectonic connection between South China and India during the Rodinia–Gondwana transition.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"433 ","pages":"Article 107996"},"PeriodicalIF":3.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145798580","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":"Tonian intra-oceanic subduction initiation at the northwestern Yangtze Block: Evidence from forearc ophiolite fragments in the Bikou microblock","authors":"Li Qin ,&nbsp;Xianzhi Pei ,&nbsp;Ruibao Li ,&nbsp;Lei Pei ,&nbsp;Chengjun Liu ,&nbsp;Zuochen Li ,&nbsp;Shaowei Zhao ,&nbsp;Feng Gao","doi":"10.1016/j.precamres.2025.107997","DOIUrl":"10.1016/j.precamres.2025.107997","url":null,"abstract":"<div><div>The Bikou Group, situated in the southern part of the Bikou microblock along the northwestern Yangtze Block, preserves extensive remnants of Tonian volcanic magmatism. However, the timing of its formation and its tectonic setting remain debated. In this study, we report a newly identified geological record of subduction initiation from the Heimulin forearc ophiolite in the Bikou microblock. The Heimulin ophiolite comprises Tonian forearc peridotites, forearc basalts (diabases), boninites, high-Mg andesites and dacites, resembling the forearc igneous sequences observed in the Izu-Bonin-Mariana (IBM) subduction zone. Forearc basalts (diabase) with zircon U-Pb ages of 841 Ma exhibit geochemical signatures similar to normal mid-ocean ridge basalts (N-MORB) but lower Ti/V ratios indicate slightly higher concentrations of fluid-mobile elements than N-MORB. In contrast, the ∼ 834 Ma boninite displays more pronounced depletion in high field strength elements (HFSEs) and Heavy rare earth elements (HREEs) compared to the FABs. The high-Mg andesites (HMAs) and dacites yield zircon U-Pb ages of 833 Ma and 825 Ma, respectively. The HMAs were derived from partial melting of a mantle wedge metasomatized by melts/fluids released from a subducting oceanic slab, whereas the dacites were produced in a mature intra-oceanic arc setting through dehydration melting of mafic rocks in the middle to lower crust. The Heimulin forearc ophiolites record a magmatic evolution from less to more HFSE-depleted and LILE-enriched, similar to the magmatic evolution of the IBM forearc, reflecting progressive subduction of the oceanic slab. Inherited zircons and negative Hf isotopes indicate the presence of ribbon-like continental fragments in the Heimulin intra-oceanic arc, which may have facilitated the initiation of Tonian intra-oceanic subduction in the Heimulin Ocean. Integrated with previously published reliable data, our study provides further evidence that the northwestern Yangtze Block experienced continuous subduction-accretion processes during the Tonian, with the Yangtze Block (South China Block) likely situated on the margin of the Rodinia supercontinent.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"433 ","pages":"Article 107997"},"PeriodicalIF":3.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145798579","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}