Gondwana Research最新文献

{"title":"Evidence for the transition from Cretaceous asthenospheric to Cenozoic lithospheric melting sources on the Chatham Islands, New Zealand","authors":"S. Homrighausen ,&nbsp;J. Schenk ,&nbsp;C. Timm ,&nbsp;F. Hauff ,&nbsp;H.J. Campbell ,&nbsp;N. Mortimer","doi":"10.1016/j.gr.2025.08.006","DOIUrl":"10.1016/j.gr.2025.08.006","url":null,"abstract":"<div><div>Late Cretaceous–Cenozoic diffuse intraplate volcanism is widespread across the continent of Zealandia, but only in the Chatham Islands have intraplate volcanoes erupted repeatedly for over 80 million years. Here we use new whole-rock major and trace element, and Sr-Nd-Pb-Hf isotope geochemical data from the Chatham Islands to characterize changes in the geochemical fingerprint of the melting sources over time to provide a better understanding of Zealandian intraplate volcanism. The first and most voluminous magmatic stage (∼85–75 Ma; Southern Volcanics) at the Chatham Islands has an isotopic signature nearly identical to the St. Helena HIMU-type end member. The following Red Bluff Tuff volcanic stage (∼65–50 Ma) has a distinct isotopic composition, influenced by an enriched mantle one-type, probably derived from the neighboring Hikurangi Plateau. The following magmatic stages, the Northern Volcanics (∼40–30 Ma) and Rangitihi Volcanics (&lt; 10 Ma) extend from this compositional array to compositions with higher ²⁰⁶Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb ratios at given ²⁰⁷Pb/²⁰⁴Pb ratio. This ‘Cenozoic array’ reflects radiogenic in-growth with high U/Pb and Th/U ratios derived from a metasomatized lithospheric mantle source. The recorded temporal geochemical evolution confirms a widespread Late Cretaceous HIMU melting event in Zealandia, which metasomatized the lithospheric mantle forming the Cenozoic HIMU-like melting source. This also reflects a change from asthenospheric to lithospheric melting sources. The nearly continuous volcanism during the Cenozoic in the Chathams and wider eastern Chatham Rise could have been triggered by asthenospheric upwelling causing melting of the base of the metasomatized lithosphere. Considering the fast-northward motion of Zealandia during the Cenozoic (∼2500 km), the upwelling is most plausibly explained by the change in lithospheric thickness caused by the partly subducted Hikurangi Plateau that lies directly north of the Chatham Islands.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"149 ","pages":"Pages 183-200"},"PeriodicalIF":7.2,"publicationDate":"2025-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145045735","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"East side story of Gondwana: the last frontier of the Arabian Nubian shield at 720 Ma based on new high-quality paleomagnetic pole","authors":"Paul Yves Jean Antonio ,&nbsp;Sonia Rousse ,&nbsp;Mélina Macouin ,&nbsp;Morgan Ganerød ,&nbsp;Damien Roques ,&nbsp;Yoann Dénèle ,&nbsp;Mathieu Benoit","doi":"10.1016/j.gr.2025.08.005","DOIUrl":"10.1016/j.gr.2025.08.005","url":null,"abstract":"<div><div>Unraveling the paleogeography is crucial to understand the changes in Earth Systems at the onset of the Cryogenian Period around ∼720 Ma. The Cryogenian Period is marked by widespread glaciations notably preserved in the Arabian Nubian Shield, and is a turning point in the supercontinent cycle between the dispersal of the Rodinia supercontinent and the assembly of Gondwana. Filling gaps from the paleomagnetic database remains an indispensable tool to solve the Proterozoic paleogeographic and paleogeodynamic puzzle, especially during challenging periods of continental dispersion. Through a detailed coupled paleomagnetic, structural and geochronologic study, the Shaat dyke swarm (∼720 Ma), intruding the Mirbat basement on the south-western coast of the Oman sultanate, has proven to be reliable witnesses of the evolution of the ancient Earth. A characteristic remanent magnetization (ChRM) was isolated in stable single to pseudo-single domain (SD/PSD) magnetite. Well constrained site mean directions obtained for 20 dykes lead to a mean direction for the Shaat dyke swarm of Dm = 249.9°, Im = −61.3° (N = 20, α95 = 5°, k = 43.1), yielding a paleomagnetic pole at 104.9°E, 25.9°N, (A95 = 7.2°, K = 21.3). The reliability of the paleomagnetic pole is assessed by 5 of the 7 Criteria of <span><span>Meert et al. (2020)</span></span>. This new key paleomagnetic Mirbat pole represents the only reliable paleomagnetic pole for the Omani Neoproterozoic block/terrane at ∼720 Ma. It confirms the connection between the Omani terrane and the Indian Shield (already link to the Seychelles and Madagascar blocks) and defines a medium paleolatitude of ∼42.4° for the Omani block at ∼720 Ma. The confirmed connection also implies a moderate latitude (∼40°) for the Indian Shield at the beginning of the major Sturtian glaciation.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"149 ","pages":"Pages 113-126"},"PeriodicalIF":7.2,"publicationDate":"2025-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145045732","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cambrian initiation of the Saxothuringian Ocean: New insights from the Kaczawa Complex, West Sudetes, Poland","authors":"Mirosław Jastrzębski ,&nbsp;Katarzyna Machowiak ,&nbsp;Andrzej Żelaźniewicz ,&nbsp;Marek Śliwiński ,&nbsp;Jiří Sláma ,&nbsp;José Manuel Fuenlabrada ,&nbsp;Jitka Míková ,&nbsp;Aleksandra Jaźwa","doi":"10.1016/j.gr.2025.08.002","DOIUrl":"10.1016/j.gr.2025.08.002","url":null,"abstract":"<div><div>The Saxothuringian Ocean originated in the Early Palaeozoic from the fragmentation of northern Gondwana. In the Kaczawa basin, a part of the Saxothuringian Ocean, sedimentary-volcanogenic deposition began during the early Cambrian. The clastic material, predominantly composed of Neoproterozoic (c. 75 %) detrital zircons, originated from source areas dominated by 0.64–0.60 Ga and 0.58–0.54 Ga-aged felsic rocks, formed within a continental magmatic arc along the Gondwanan margin. This Ediacaran magmatism facilitated the recycling of older Gondwanan crust, which incorporated Cryogenian (0.75–0.73 Ga), Tonian-Stenian (1.2–0.9 Ga), Paleoproterozoic (2.2–1.8 Ga), and Archean (3.4–2.4 Ga) components. These inputs are reflected in εHf(t) values (–35.0 to +12.8) and TDM(Hf) ages (2.6–0.7 Ga), indicating a complex structure of the Gondwanan margin. The older continental crust of this margin gained juvenile additions from the mantle around 1.0 Ga and 0.72–0.53 Ga, supported by positive Hf zircon and whole rock Nd isotopic evidence. Though absent in the Kaczawa Complex today, such rocks were likely eroded alongside volcanic ash falls during the Cambrian. Detritus is interpreted to be transported from the Saharan Metacraton, the Trans-Saharan Belt, and the Anti-Atlas domain, shaped by the drainage systems of northern Gondwana. Contributions from the West African Craton cannot be ruled out, but the source regions exhibit greater complexity than this single craton. Mafic volcanism, ranging from WPB to OIB types with TDM(Nd) ages of 0.72–0.53 Ga began in the early Cambrian. This was accompanied by intermediate volcanic differentiates (TDM(Nd) 0.7–0.5 Ga) and felsic effusives (TDM(Hf, Nd) ages of 1.2–0.9 Ga), with volcanic activity peaking 500–490 Ma. This early evolution of the Kaczawa Complex reflects a continental rift-back arc basin system linked to oceanic subduction beneath the extended Gondwanan margin. This setting involved mantle wedge melting, differentiation and contamination by subducted sediments and materials from the upper plate.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"149 ","pages":"Pages 212-228"},"PeriodicalIF":7.2,"publicationDate":"2025-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145060794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phosphorus release and microbial community alterations in submerged areas of Qinghai Lake","authors":"Daye He ,&nbsp;Yiming Zhao ,&nbsp;Feifei Che ,&nbsp;Shuhang Wang ,&nbsp;Xia Jiang ,&nbsp;Fuwen Deng ,&nbsp;Xufeng Mao ,&nbsp;Zheng Yu ,&nbsp;Yunyan Guo","doi":"10.1016/j.gr.2025.08.007","DOIUrl":"10.1016/j.gr.2025.08.007","url":null,"abstract":"<div><div>The formation of submerged areas in Qinghai Lake, driven by rising water levels, has resulted in substantial changes in environmental characteristics, phosphorus dynamics, and microbial community composition. Climate-driven hydrological expansion promotes phosphorus remobilization in submerged sediments, necessitating targeted management to mitigate eutrophication risks in Qinghai Lake and analogous alpine ecosystems. This study examines the impacts of submersion on water chemistry, sediment properties, and microbial communities across multiple sites around the lake, including submerged regions, estuaries, and the lake body. Water quality analysis revealed that eutrophication and pollution were more pronounced in flooded areas compared to the lake and estuarine zones, with particulate matter and chlorophyll significantly increased. pH and redox potential measurements revealed that submerged areas exhibited similar characteristics to the lake, with elevated pH and distinct redox shifts. Sediment analysis demonstrated significant changes in particle composition, with coarse sands larger than 0.63 mm accounting for most of the sediment in submerged zones, whereas finer particles (&lt;0.16 mm) predominated in the lake and estuarine sediments, reflecting alterations in sediment texture due to flooding. Phosphorus concentration in water bodies was significantly elevated in submerged areas, with higher levels of both total phosphorus and inorganic phosphorus forms compared to the lake. Moreover, microbial diversity analysis indicated that microbial communities in submerged areas exhibited distinct characteristics from those in the lake and estuary, with greater complexity in co-occurrence networks and shifts in dominant microbial taxa, notably <em>Rhodobacteraceae</em> and <em>Pseudomonadaceae</em>. The abundance of phosphorus-related genes, particularly those involved in phosphate metabolism, was higher in submerged areas, indicating an enhanced microbial contribution to phosphorus cycling. These findings suggest that newly submerged zones not only accelerate internal phosphorus loading but also restructure microbial networks, thereby enhancing the risk of eutrophication. It emphasized shifts in nutrient cycling and microbial dynamics that may affect the overall health and stability of the aquatic ecosystem.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"150 ","pages":"Pages 14-22"},"PeriodicalIF":7.2,"publicationDate":"2025-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145242559","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The lower Cambrian selenium-enriched black rock series in Southwest China: Occurrence modes and surface environmental implications","authors":"Dinghui Liu ,&nbsp;Yonglin Liu ,&nbsp;Xinglei Tian ,&nbsp;Yuyang Yuan ,&nbsp;Jingyun Wang ,&nbsp;Huixian Xiao ,&nbsp;Mingyang Zhong ,&nbsp;Xiaorong Deng ,&nbsp;Cheng Chen","doi":"10.1016/j.gr.2025.07.028","DOIUrl":"10.1016/j.gr.2025.07.028","url":null,"abstract":"<div><div>Selenium (Se) is commonly enriched in Lower Cambrian black shales, which are highly susceptible to weathering and may release Se into the surficial environment. However, variations in Se content, enrichment mechanisms, and occurrence modes across contrasting depositional settings remain poorly constrained, as do their environmental implications. This study presents a comparative geochemical analysis of two Lower Cambrian black shale formations in South China: the Niutitang Formation (shallow marine shelf) and the Lujiaping Formation (shallow to semi-deep marine). The Lujiaping Formation exhibits significantly higher Se concentrations (0.15–27.5 mg/kg; mean 5.37 mg/kg) and enrichment factors (Se_EF = 21.39) than the Niutitang Formation (0.14–7.37 mg/kg; mean 1.02 mg/kg; Se_EF = 1.10). Sequential extraction results show that Se in the Niutitang Formation mainly occurs in Fe-Mn oxide-bound (36 %), organic-bound (32 %), and residual (31 %) forms, while Se in the Lujiaping Formation is predominantly organic-bound (66 %). Risk assessment based on the Risk Assessment Code (RAC) indicates that all Niutitang samples pose low risk (1 % ≤ RAC &lt; 10 %), whereas 13 % of Lujiaping samples fall within the medium-risk category (10 % ≤ RAC &lt; 30 %). The Ratio of Secondary to Primary phases (RSP) reveals high pollution potential (RSP ≥ 3) in all Lujiaping samples and in 50 % of Niutitang samples. In the Niutitang Formation, Se is chiefly derived from weathered terrigenous detritus and deposited under anoxic conditions, whereas in the Lujiaping Formation, Se originates mainly from hydrothermal fluids, with deposition influenced by both anoxia and total organic carbon (TOC). These findings provide new insights into Se mobility and enrichment in early Paleozoic marine environments and offer a scientific basis for evaluating environmental risks and the sustainable use of Se-rich soils derived from weathered black shales.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"149 ","pages":"Pages 127-140"},"PeriodicalIF":7.2,"publicationDate":"2025-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145045733","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Beyond the surface: how dissolved organic matter recasts the biogeochemical behaviors of micro- and nanoplastics in aquatic environments","authors":"Haojie Chen ,&nbsp;Danlian Huang ,&nbsp;Ruihao Xiao ,&nbsp;Wei Zhou ,&nbsp;Lingshi Yin ,&nbsp;Rui Deng ,&nbsp;Hai Huang ,&nbsp;Yang Lei ,&nbsp;Ruijin Li","doi":"10.1016/j.gr.2025.08.009","DOIUrl":"10.1016/j.gr.2025.08.009","url":null,"abstract":"<div><div>Micro- and nanoplastics (MNs) and dissolved organic matter (DOM) widely coexist in aquatic environments, and their interactions are receiving increasing attention. These interactions influence the biogeochemical behaviors of plastic particles in natural systems. However, the behavioral characteristics, fate processes, and ecotoxicological impacts of MNs under DOM involvement have not been systematically analyzed. Therefore, this review summarizes the promotion and inhibition mechanisms of DOM on MNs photoaging, in which the primary chromophore (light-absorbing entity) of DOM can induce the production of triply excited state DOM (³DOM*) and reactive oxygen species (ROS) to promote MNs photoaging, or alternatively, limit MNs photoaging by shielding light and scavenging the reactive intermediates. The effect of DOM on the stability of MNs particles is emphasized, where forces such as hydrogen bonding, coulombic forces, hydrophobic forces, and π-π bonding can help mediate the interaction between DOM and MNs, with the resulting additional electrostatic and spatial effects subsequently dominating the aggregation, deposition, and transport behaviors of the particles. The impacts of DOM on the adsorption of inorganic and organic pollutants in water by MNs and their corresponding interference mechanisms are discussed. Additionally, special attention focuses on the toxicological effects on aquatic biota of the ecological and biological corona formed by DOM with MNs, which provides a protective coating that reduces the physicochemical toxicity of particles, but in certain cases, it may exacerbate toxicity. Finally, knowledge gaps that need to be addressed for DOM-MNs interactions and related effects, as well as future research directions are presented.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"149 ","pages":"Pages 98-112"},"PeriodicalIF":7.2,"publicationDate":"2025-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145045728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhancing landslide susceptibility mapping in the Himalayas: geospatial and machine learning with explainable AI (XAI)","authors":"Manas Utthasini ,&nbsp;Idhayachandhiran Ilampooranan ,&nbsp;Suraj Kumar Singh ,&nbsp;Shruti Kanga ,&nbsp;Pankaj Kumar ,&nbsp;Krishnagopal Halder ,&nbsp;Biswajeet Pradhan ,&nbsp;Amit Kumar Srivastava ,&nbsp;Ranit Sundar Chatterjee ,&nbsp;Rabin Chakrabortty ,&nbsp;Tarig Ali ,&nbsp;Gowhar Meraj","doi":"10.1016/j.gr.2025.08.003","DOIUrl":"10.1016/j.gr.2025.08.003","url":null,"abstract":"<div><div>Landslides present a critical hazard in the Himalayas, where steep topography, intense rainfall, and tectonic activity converge to destabilize slopes. Accurate delineation of high-susceptibility zones is essential to safeguard lives, infrastructure, and ecosystems. Here, we construct a comprehensive Landslide Susceptibility Map (LSM) for Uttarakhand, a landslide-prone state in northern India, by integrating advanced ensemble machine learning (ML) with explainable AI. Our analysis comprises 35 geo-environmental variables, ranging from historical landslide inventories and remote sensing data to GIS-based geomorphological, hydrological, and anthropogenic layers. We evaluate six ML models (Logistic Regression, Support Vector Machine, Random Forest, Extra Trees, Gradient Boosting, and eXtreme Gradient Boosting) before consolidating them into a stacking ensemble (SE), achieving an Area Under the Curve (AUC) of 0.987 on the training set and 0.979 on the test set. Across models, false-negative rates were low; Extra Trees minimized missed events (FNR = 3.5 %) but with a high false-positive rate (23.6 %), whereas XGBoost and the SE achieved a better sensitivity–specificity balance (FNR = 5.6 and 5.5 %, respectively) with comparatively lower false positives, favoring operational use. Spatial transferability to Sikkim was strong (Uttarakhand test accuracies 0.864–0.917; Sikkim 0.905–0.971), with XGBoost yielding the highest Sikkim test accuracy (0.971) and ensemble approaches (GB, XGBoost, SE) all exceeding 0.96, highlighting robust generalization across different Himalayan regions. Our ensemble model surpasses all individual models and classifies the study area into five susceptibility zones (very low to very high), with 18.20 % of Uttarakhand, particularly in Pithoragarh, Chamoli, and Rudraprayag districts, falling under high-susceptibility zones. Further interpretability is provided by SHapley Additive exPlanations (SHAP), which highlight key drivers of slope failure, including slope angle, fault proximity, and rainfall. Our findings highlight the value of combining robust ML techniques with geoscientific data, thereby enhancing hazard assessments and informing disaster risk reduction across the Himalayas and similarly vulnerable terrains worldwide.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"149 ","pages":"Pages 262-290"},"PeriodicalIF":7.2,"publicationDate":"2025-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145118314","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Editorial Board (IFC)","authors":"","doi":"10.1016/S1342-937X(25)00259-X","DOIUrl":"10.1016/S1342-937X(25)00259-X","url":null,"abstract":"","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"148 ","pages":"Page IFC"},"PeriodicalIF":7.2,"publicationDate":"2025-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144988162","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tectonic setting and evolution of the Kangguer Ocean: New constraints from structural and geochemical analyses of the late Paleozoic Kangguer mélange belt in Eastern Tianshan, NW China","authors":"Wei Wang ,&nbsp;Guocan Wang ,&nbsp;Zeyou Xuan ,&nbsp;Ali Polat ,&nbsp;Jialong Feng ,&nbsp;Meng Zhang ,&nbsp;Ruilu Guo ,&nbsp;Tianyi Shen","doi":"10.1016/j.gr.2025.07.027","DOIUrl":"10.1016/j.gr.2025.07.027","url":null,"abstract":"<div><div>Deciphering the lithological and structural characteristics of mélanges in orogenic systems is crucial for understanding their tectonic setting, subduction polarity, and the evolution of closed oceanic basins. Here, we report new structural, geochronological, and geochemical data from the Kangguer mélange belt, situated between the North Tianshan Belt and the Central Tianshan Block in Eastern Tianshan, NW China, to elucidate the evolution of this previously proposed tectonic boundary. Detailed field mapping and structural anatomy reveal that the Kangguer mélange belt consists of accreted and dismembered ocean plate stratigraphy. Zircon U-Pb ages of basalts, gabbros, forearc siltstones, and sandstone matrices indicate the mélanges formed at ca. 312–288 Ma. Combined with maximum depositional ages of <em>retro</em>-foreland sandstones and crystallization ages of syn-accretionary and post-kinematic intrusions, the timing of tectonic stacking and terminal accretion is constrained at ca. 286–280 Ma. Geochemically, the massive basalts and gabbros display both normal mid-ocean ridge basalt (N-MORB) and island-arc tholeiite (IAT) affinities, suggesting they formed in the subduction zone-distal spreading centers of a back-arc basin. In contrast, the pillow basalts and their underlying gabbros exhibit enriched MORB-like signatures, likely representing accreted seamounts that are ascribed to plume-ridge interaction. These data, together with structural and paleogeographical evidence, indicate that the Kangguer mélange formed in a back-arc setting during the Early Carboniferous to Early Permian (ca. 336–288 Ma), rather than representing a mid-ocean-ridge-type oceanic lithosphere sustaining into the Early Triassic. Kinematic indicators, spatial distribution of subduction-related magmatism, and provenance analyses support a model of bidirectional subduction-accretion within the Kangguer back-arc basin. Integrating our new results with previously published data, we propose that the formation of the Kangguer back-arc basin was likely triggered by the north-dipping subduction of the South Tianshan Ocean, and the mélange records bidirectional subduction-accretion processes and a terminal arc-continental collision at ca. 286–280 Ma.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"149 ","pages":"Pages 70-97"},"PeriodicalIF":7.2,"publicationDate":"2025-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145020315","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Persistent Amazonian and West African detrital zircon signature in the northern Mauritanide Belt","authors":"Roberto Jiménez Borrego ,&nbsp;David Martínez Poyatos ,&nbsp;Antonio Azor ,&nbsp;Cristina Accotto ,&nbsp;Antonio Jabaloy-Sánchez ,&nbsp;Francisco González Lodeiro ,&nbsp;Mohamed Salem Sabar ,&nbsp;Ahmed Hamoud ,&nbsp;Ahmed Ould Ely Lekouyrie","doi":"10.1016/j.gr.2025.07.026","DOIUrl":"10.1016/j.gr.2025.07.026","url":null,"abstract":"<div><div>We provide new detrital zircon U/Pb geochronological data from nine samples of Neoproterozoic–Cambrian metasedimentary rocks of the northern Mauritanide Belt, aiming at constraining depositional ages and provenance in the paleotectonic context of the Rodinia to Gondwana supercontinent transition. The youngest detrital zircon populations indicate the following maximum depositional ages: c. 900 Ma (early Tonian) for the Atilis Quartzite Formation, c. 660 Ma (Cryogenian) for the gneissic Hajar Dekhen-Kleouat Unit, c. 580 Ma (middle Ediacaran) for the Atomai Formation, and c. 540 Ma (late Ediacaran–early Cambrian) for the Sainte Barbe Formation and the ophiolite-like Agoualilet Unit. Two types of zircon age distributions were identified, reflecting the most reliable original sources. Type I age spectra include c. 2.8 Ga, 2.1 Ga and 0.6 Ga age populations, which are interpreted to derive from West African Craton sources (Leonian/Liberian, Eburnean, Pan-African orogenies). Type I signature is found in the Atomai and Sainte Barbe formations and the Agoualilet Unit. Type II age spectra include, besides the type I populations, c. 1.8, 1.5, 1.2 and 1.0 Ga age populations, which are thought to derive from sources in the Amazonian Craton (Central Amazonian, Trans-Amazonian, Rio Negro-Juruena, Rondonian-San Ignacio, Sunsás-Grenvillian and Brasiliano orogenies). Type II signature is found in the Atilis Quartzite and Atomai formations, Hajar Dekhen-Kleouat Unit, and the Cambrian Nouatil Group (intra-WAC Taoudeni Basin). The changes in the detrital zircon record through the studied Neoproterozoic–Cambrian successions resulted from shifts in drainage systems and alternating sediment supply from both the West African and the Amazonian cratons along most of the Neoproterozoic period. Finally, we interpret that the subsequent opening of a short-lived oceanic realm (the Clymene Ocean) during the latest Ediacaran between the West African and the Amazonian cratons interrupted the direct sediment supply from the Amazonian Craton.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"149 ","pages":"Pages 1-16"},"PeriodicalIF":7.2,"publicationDate":"2025-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144916819","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}