Gondwana Research最新文献

{"title":"Microcontinental collision in the East Gondwana orogen: Evidence from geology, geochemistry, and geochronology of the collision boundary “Berrnabbane” in the Lützow-Holm Complex, East Antarctica","authors":"Nobuhiko Nakano ,&nbsp;Sotaro Baba ,&nbsp;Shin-ichi Kagashima ,&nbsp;Ji Wan Jeong ,&nbsp;Fransiska Ayuni Catur Wahyuandari","doi":"10.1016/j.gr.2025.02.023","DOIUrl":"10.1016/j.gr.2025.02.023","url":null,"abstract":"<div><div>This study focuses on the unexplored outcrop “Berrnabbane” in the western Lützow-Holm Complex, eastern Dronning Maud Land within East Gondwana orogen. Various protolith ages are identified from the small outcrop, which can be considered as small-scale analogs of the extensive Lützow-Holm Complex. These rocks with different protolith ages are in contact with each other without obvious shear zones. The central to the southern part is composed of felsic gneiss with a protolith age of 2.5 Ga. These rocks are derived from a microcontinent formed by slab melting in an initial island arc tectonic setting. The central Berrnabbane includes felsic gneiss and mafic granulite with a protolith age of 1.9 Ga. These rocks are enclosed within pelitic gneiss, with a maximum depositional age of 1.8 Ga. These rocks correspond to the continental margin arc, including an accretionary prism developed around the 2.5 Ga microcontinental margin. The northern part comprises felsic gneiss with a protolith age of 1.0 Ga, which originated from another juvenile continent. The duration of metamorphism differs between rocks with the 2.5 Ga (with 1.9–1.8 Ga reworked margin) and the 1.0 Ga continents. Both share the event during 550–500 Ma, whereas only the 2.5 Ga continent preserves former thermal events from ∼ 600 Ma. The earlier event might be the crustal thickening caused by the collision and burial of the 2.5 Ga microcontinent beneath the 1.0 Ga continent, and the latter event should be a cratonic collision known as the Kuunga Orogeny. The prolonged orogenesis preserved only in the 2.5 Ga microcontinent suggests that radiogenic heat production would play an important role in extremely high-temperature metamorphism in the East Gondwana orogeny. The present results indicate that the Lützow-Holm Complex correlates more closely with the Sri Lankan Complexes than with other complexes in Dronning Maud Land during the amalgamation of Gondwana.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"142 ","pages":"Pages 73-91"},"PeriodicalIF":7.2,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143685362","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 Igla Sn-(W-Be) deposit, Egypt: Prolonged magmatic-metasomatic processes during the middle stage evolution of the Arabian-Nubian Shield","authors":"Basem Zoheir ,&nbsp;Patrick Carr ,&nbsp;Xinyue Xu ,&nbsp;Armin Zeh ,&nbsp;Dennis Kraemer ,&nbsp;Ryan McAleer ,&nbsp;Matthew Steele-MacInnis ,&nbsp;Azza Ragab ,&nbsp;Fatma Deshesh","doi":"10.1016/j.gr.2025.02.021","DOIUrl":"10.1016/j.gr.2025.02.021","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The Igla Sn-(W-Be) deposit in the Central Eastern Desert of Egypt is associated with a suite of granitic rocks, including monzogranite, granophyric granite, and porphyritic leucogranite. These rocks belong to a calcic to calc-alkalic series, characterized by low Mg# values and low Ti and P concentrations. Monzogranite and granophyric granite show features typical of fractionated volcanic-arc I-type granites, while the leucogranite, with its distinct Rb/Ba, K/Rb, and Ga/Al ratios, is classified as a highly evolved A-type granite. Mineralization at Igla mine includes cassiterite and wolframite, along with minor molybdenite, arsenopyrite, columbite, and tourmaline, mainly hosted in beryl ± topaz-quartz veins and miarolitic cavities within greisen and silica-rich stockwork.&lt;/div&gt;&lt;div&gt;Zircons from the monzogranite show LREE enrichment, moderate positive Ce anomalies, and moderately oxidizing conditions (ΔFMQ ≃ 1.75), while granophyric granite zircons exhibit higher HREE enrichment and more oxidizing conditions (ΔFMQ ≃ 1.04). Leucogranite zircons have the highest REE concentrations, more pronounced negative Eu anomalies, and distinctly reducing conditions (ΔFMQ ≃ -0.06). U–Pb dating of zircon and xenotime reveals concordant &lt;sup&gt;206&lt;/sup&gt;Pb/&lt;sup&gt;238&lt;/sup&gt;U ages of 708.7 ± 2.0 &lt;!--&gt; &lt;!--&gt;Ma for monzogranite, 701.3 ± 1.5 Ma for the granophyric granite, and a noticeably younger age for the leucogranite (605.1 ± 2.4 Ma).&lt;/div&gt;&lt;div&gt;Petrography and microchemistry of cassiterite reveal two distinct stages: an earlier generation (Cst-I) with straight oscillatory zoning, and a later chaotically zoned generation (Cast-II) that overgrows and crosscuts the former. U-Pb dating confirms two discernable age populations: Cst-I, with a weighted mean &lt;sup&gt;206&lt;/sup&gt;Pb/&lt;sup&gt;238&lt;/sup&gt;U age of 637.4 ± 1.4 Ma; and Cst-II ages scatter from 605 to 588 Ma, partially overlapping with the leucogranite formation. Wolframite, although less precisely dated at 615.3 ± 4.3 Ma, suggests rejuvenated tectonics, magmatism, and hydrothermal activities, culminating in the formation of Cst-II. Primary aqueous fluid inclusions in quartz indicate deposition from a low-salinity aqueous fluid with undetectable dissolved gas, while trails of aqueous-carbonic inclusions with slightly higher salinity and appreciable gas (CO&lt;sub&gt;2&lt;/sub&gt;, CH&lt;sub&gt;4&lt;/sub&gt;) contents occur together in the same crosscutting trails with arsenopyrite and bismite inclusions. The variable contents of CO&lt;sub&gt;2&lt;/sub&gt; and CH&lt;sub&gt;4&lt;/sub&gt; in these inclusions suggest that carbon redox equilibria within the ore-forming fluid may have played a pivotal role in linking redox potentials, facilitating the deposition of arsenopyrite, bismite, and Cst-II.&lt;/div&gt;&lt;div&gt;The improved age constraints highlight the role of highly evolved transcrustal magmatism in mobilizing and upgrading early rare metal concentrations, coinciding with the ∼ 650–600 Ma geodynamic transition in the Arabian-Nubian Shield. Crustal thinning, partial melting ","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"142 ","pages":"Pages 20-43"},"PeriodicalIF":7.2,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143643187","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)00050-4","DOIUrl":"10.1016/S1342-937X(25)00050-4","url":null,"abstract":"","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"140 ","pages":"Page IFC"},"PeriodicalIF":7.2,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143592486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Paleoenvironmental evolution and isotopic stratigraphy of the Lower Cambrian in the Tarim Basin: Implications for global paleoenvironmental reconstruction","authors":"Weijing Liu ,&nbsp;Keyu Liu ,&nbsp;Yaxin Shang ,&nbsp;Yifan Zhang ,&nbsp;Jianliang Liu ,&nbsp;Kuanhong Yu","doi":"10.1016/j.gr.2025.02.022","DOIUrl":"10.1016/j.gr.2025.02.022","url":null,"abstract":"<div><div>The Ediacaran-Cambrian transition marks a critical period in Earth’s history, characterized by significant shifts in continental configuration, biological evolution, climate, and ocean geochemistry. This study examines the paleoenvironmental evolution of the Lower Cambrian in the Tarim Basin, NW China, through a detailed analysis of carbon (δ¹³C), oxygen (δ¹⁸O), and strontium (⁸⁷Sr/⁸⁶Sr) isotopic stratigraphy, along with rare earth and trace elements. Using samples from the Luntan-1 and Zhonghan-1 wells, we identified substantial isotopic variations, with δ¹³C values ranging from −1.98‰ to −5.18‰ in Luntan-1 and −6.39‰ to −0.63‰ in Zhonghan-1, and ⁸⁷Sr/⁸⁶Sr ratios from 0.708709 to 0.711123 in Luntan-1 and 0.715349 to 0.725398 in Zhonghan-1. The δ¹⁸O values indicate fluctuations in ocean temperatures and regional conditions, while REE and trace elements suggest influence from submarine hydrothermal activities and variable redox conditions during deposition. The δ¹³C excursions correlate with global events such as the Basal Cambrian Carbon Isotope Excursion (BACE) and the Cambrian Explosion, linking isotopic signatures to global carbon cycle disruptions and major biological shifts. The elevated ⁸⁷Sr/⁸⁶Sr ratios reflect regional influences like continental weathering and hydrothermal activity. This study underscores the importance of redox conditions in early Cambrian ecosystem development and offers insights into the interplay of tectonics, climate, and biology during this transformative period, contributing to future paleoclimatology and geochemistry research.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"141 ","pages":"Pages 332-348"},"PeriodicalIF":7.2,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143682115","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":"Occurrence and enrichment mechanisms of helium in geothermal systems in continental China","authors":"Yinlei Hao ,&nbsp;Yingchun Wang ,&nbsp;Xingxing Kuang ,&nbsp;Zhonghe Pang ,&nbsp;Yiman Li ,&nbsp;Yuqing Feng ,&nbsp;Hui Zhou ,&nbsp;Nianqing Li ,&nbsp;Yuanzhi Cheng ,&nbsp;Liwu Li ,&nbsp;Lantian Xing ,&nbsp;Qinghua Gong","doi":"10.1016/j.gr.2025.02.020","DOIUrl":"10.1016/j.gr.2025.02.020","url":null,"abstract":"<div><div>Helium (He) is an indispensable and scarce strategic resource. We compiled 682 published He concentration and He–Ne–C–N isotopes data points for geothermal volatiles in continental China to systematically investigate distribution and enrichment mechanisms of helium in geothermal systems by linking fluid geochemistry with crustal structures, lithologies and thermal regimes. Active volcanic centres can be regarded as lower-priority helium provinces (He &lt; 0.05 vol%), with up to 79 % of He from depleted MORB-type mantle. Samples with He concentrations up to standards for commercial He resources (He &gt; 0.1 vol%) are widely distributed in the nonvolcanic geothermal systems, and can be classified as He-rich N₂ type (81 %), He-rich CO₂ type (15 %) or He-rich CH₄ type (4 %) gases. Helium in nonvolcanic regions has a purely crustal or crustal–mantle complex origin, with subcontinental lithospheric mantle contributions of &lt; 40 %. The widely distributed Proterozoic to Cenozoic granitic rocks are the dominant He source rocks, with average ⁴He production rates 2.0–7.2 times that of the average crust. He-rich gases in all tectonic units are characterized by ⁴He/N₂ ratios of 0.001 to 0.44, likely formed by variable mixing of a crustal component (radiogenic ⁴He and He-associated N₂) from granitic and metamorphic basements, and sedimentary (e.g., N₂ and CH₄) and atmospheric (i.e., N₂ and ²⁰Ne) components at shallow levels. In addition to these processes, in the Tibetan Plateau and eastern China, CO₂ derived from mantle and metamorphic decarbonation at depths &gt; 10–11 km can strip He generated and accumulated in the crust, carrying it to shallow geothermal reservoirs along large-scale faults. Subsequent CO₂ loss (93–99 % on average) by calcite precipitation and dissolution processes can enrich He and N₂, forming He-rich N₂ type gases. Extremely He-rich geothermal fields (He ≥ 0.5 vol%) are distributed mainly along the Indus–Yarlung suture zone, southern Tibet detachment system and Anninghe fault in the Tibetan Plateau, the Weihe Basin and local regions in eastern China due to the existence of favorable crustal structures, and are potential sites for future helium exploration.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"141 ","pages":"Pages 289-309"},"PeriodicalIF":7.2,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143610712","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 Permian-Triassic volcanic activity in the West Siberian basin: A buried silicic LIP coeval to the Siberian Traps","authors":"Anton Latyshev ,&nbsp;Ivan Panchenko ,&nbsp;Maria Smirnova ,&nbsp;Peter Kulikov ,&nbsp;Yuliya Trushkova ,&nbsp;Elena Sapogova ,&nbsp;Alexey Bakulin","doi":"10.1016/j.gr.2025.02.019","DOIUrl":"10.1016/j.gr.2025.02.019","url":null,"abstract":"<div><div>Traps of the Siberian platform and associated basaltic rifts in the West Siberian basin constitute one of the most voluminous continental Large Igneous Provinces (LIP). The contribution of silicic volcanic rocks to this vast province was underestimated. We present results of the first comprehensive study of silicic rocks from the Froly-Krasnoleninsky region (the central part of West Siberia). Permian-Triassic volcanics in this area are buried under the thick sedimentary cover (2.5–3.5 km) and are available only as drill cores. Volcanic rocks fill the Rogozhnikov-Nazym graben and other rifts.</div><div>The volcanic sequence in this area is dominated by lavas of rhyolitic-dacitic composition, which exhibit similar petrographic and geochemical characteristics in all studied districts. A complex of structural and geochemical features of silicic rocks corresponds to the tectonic setting of post-collisional rifting. Basalts are subordinate and similar to those from middle-upper parts of the Noril’sk volcanic section (the Siberian platform). Based on geochemical features, we suggest that silicic rocks are derived mainly from the partial melting of mafic lower continental crust due to the input of additional heat from the Siberian mantle plume. Late Paleozoic crust of the central part of West Siberia, saturated with mafic underplates during prior subduction events, provided favorable conditions for the generation of silicic magmas, while post-collisional rifts acted as magma-conducting zones.</div><div>Nine new U-Pb ages constrain the timing of silicic volcanic activity in West Siberia as ∼5–10 Myr at the Permian-Triassic boundary (253.69–248.21 Ma), which is nearly coeval to the main phase of the Siberian Traps emplacement. Temporal and spatial relationships, along the geochemical similarity of the silicic and mafic rocks confirm their genetic relations. In total, silicic rocks occupy about 10⁵ km² within the West Siberian basin and can be considered as a Silicic Large Igneous Province (SLIP), coeval and genetically linked to the mafic Siberian Traps LIP.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"141 ","pages":"Pages 246-264"},"PeriodicalIF":7.2,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143600159","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":"A billion years of geological drama – Boring or brilliant?","authors":"Indrani Mukherjee ,&nbsp;Ross Corkrey ,&nbsp;Daniel Gregory ,&nbsp;Ross Large ,&nbsp;Anthony M. Poole","doi":"10.1016/j.gr.2025.02.018","DOIUrl":"10.1016/j.gr.2025.02.018","url":null,"abstract":"<div><div>Used to describe the Paleo-Mesoproterozoic era (1800–800 Ma), the term «Boring Billion» is, in many ways, a misnomer. The conventional focus on the significance of pO₂ for life, along with the discovery of the first metazoans in the rock record around 800 million years ago (according to molecular clock estimates), and the enduring human interest in later Ediacaran macroscopic fossils, are just a few factors contributing to this undeserved characterization. Initially perceived as a phase of geological inertia that may have hindered biological development, recent research has illuminated pivotal milestones in both environmental and biological domains throughout the ’Boring Billion.’ Through a thorough review of existing literature, we present a discussion encompassing plate tectonics, atmosphere–ocean chemistry, nutrient cycling, temperature fluctuations, and mineral evolution. Furthermore, we explore significant biological phenomena such as eukaryogenesis, predation, and potential metazoan origins, contextualizing these events within the broader geo-biological narrative of the period.</div><div>Our discussion delves into the latest research within the realm of established notions about this era. We emphasize the abiotic factors that influenced life’s evolution, drawing parallels between contemporary geochemical trends and the evolution of complex life forms, including animals. We also delve into the prerequisites and origins of eukaryogenesis, exploring diversification during the Middle Proterozoic. Furthermore, we examine the role of environmental cues in driving biological innovation throughout this billion-year span. This research offers an alternative lens through which to interpret geological trends and the evolutionary trajectory of complex life. By spotlighting shifts in Earth system processes—such as plate tectonics, atmosphere–ocean redox dynamics, marine nutrient cycles, and biological evolution—during the “Boring Billion”, our study invites readers to critically assess this significant era in Earth’s history.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"142 ","pages":"Pages 1-19"},"PeriodicalIF":7.2,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143637268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Government ecological concern and its impact on synergistic pollution and carbon reduction: Evidence from China","authors":"Xueyang Wang ,&nbsp;Wenling Liu ,&nbsp;Xiumei Sun ,&nbsp;Mahmood Ahmad ,&nbsp;Jiawei Chen","doi":"10.1016/j.gr.2025.02.016","DOIUrl":"10.1016/j.gr.2025.02.016","url":null,"abstract":"<div><div>This study addresses the increasingly prominent issues stemming from the ongoing degradation of the ecological environment, which pose significant threats to human well-being and have consequently compelled the government to heighten its focus on environmental concerns. With a particular emphasis on the government’s ecological concerns, this study investigates their role in promoting collaborative governance for pollution reduction and carbon mitigation. Employing the fully modified ordinary least squares (FMOLS) and dynamic ordinary least squares (DOLS) methods, this research analyzes the relationship between government ecological concern and the effectiveness of collaborative governance in pollution and carbon reduction. The findings indicate that the government’s ecological concern, economic development, industrial structure, and trade openness can improve the performance of pollution reduction and carbon reduction collaborative governance. Conversely, a negative correlation is observed between urbanization and the effectiveness of such collaborative efforts. Notably, among various categories of government ecological concern, greater attention directed towards environmental pollution, energy consumption, and natural resource management significantly improves the performance of collaborative governance in pollution and carbon reduction. The positive impact of government ecological governance is not consistently sustained; it primarily affects collaborative pollution reduction and carbon mitigation governance at the middle to lower percentiles and exhibits a diminishing effect over time. The causality analysis results of Dumitrescu and Hurlin demonstrate the presence of a reciprocal causal relationship between the government’s ecological concern and pollution reduction and carbon reduction collaborative governance, while there exists a single causal link between economic development, industrial structure, trade opening, urbanization, and pollution reduction and carbon reduction collaborative governance. Drawing on these results, this study presents pertinent policy recommendations to inform and guide pollution reduction and carbon mitigation initiatives, thereby providing valuable insights and references for collaborative governance in this domain.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"141 ","pages":"Pages 180-194"},"PeriodicalIF":7.2,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143547080","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":"Evidence of magmatic versus hydrothermal zircon ages and mantle-crust interactions obtained from the Carboniferous alkaline intrusions at the margin of East European Craton (NE Poland)","authors":"E. Krzemińska ,&nbsp;L. Krzemiński ,&nbsp;D. Demaiffe ,&nbsp;P. Poprawa ,&nbsp;I.S. Williams ,&nbsp;J. Wiszniewska","doi":"10.1016/j.gr.2025.01.017","DOIUrl":"10.1016/j.gr.2025.01.017","url":null,"abstract":"<div><div>The Mazury Alkaline Intrusions (MAI), consisting of both silica-oversaturated and undersaturated rocks, are situated at the tectonically weakened western margin of the East European Craton (EEC). SHRIMP zircon U-Pb dating of nine syenitic samples, combined with zircon δ¹⁸O oxygen isotope data and mineral chemistry, provides insight into the Carboniferous magmatic-to-hydrothermal evolution of the MAI. Three magmatic pulses, at 352 ± 3 Ma, 344 ± 3 Ma and 337 ± 2 Ma, have been recognized. Each was followed closely by hydrothermal activity, dated at 351 ± 3 Ma, 347 ± 5 Ma and 333 ± 12 Ma, respectively. The hydrothermal stages were identified from hydrothermal zircon in the silica undersaturated syenites; its porous texture, its high abundance of non-formula elements (LREE, Y, Th, U) and its depletion in ¹⁸O, in some cases resulting in negative δ¹⁸O values. The zircon with higher δ¹⁸O values in the silica oversaturated syenites reflects crystallization from crustal melt, consistent with negative whole rock εNd(t) values ranging from −3.19 to −5.02, indicative of melts generated in the lower crust. Positive whole-rock εNd(t) values, from + 2.34 to + 0.86, obtained from undersaturated nepheline syenites indicate a depleted mantle source. T_DM model ages calculated for rocks from the MAI, and from the Devonian Kola province and Permian Oslo rift, reveal a similar interval of 0.74–0.62 Ga, pointing to common geodynamic processes having affected the EEC margins during the Neoproterozoic break-up of Rodinia. The intraplate MAI differs from the typical late Paleozoic rift-related alkaline provinces of the EEC. The newly identified phases of the MAI magmatism coincide in time with the Variscan continent/continent collision. This might have led to transmission of lithospheric-scale tectonic stress into the far foreland of the orogen, including the western EEC, and possibly also to the strike-slip reactivation of pre-existing tectonic zones, resulting in local mantle decompression.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"142 ","pages":"Pages 44-72"},"PeriodicalIF":7.2,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143685363","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 evolution of the Proto-Paleo-Tethys in the West Kunlun orogenic belt: Constraints from U-Pb geochronology of detrital zircons","authors":"Yang Gao ,&nbsp;Lin Jiang ,&nbsp;Weiyan Chen ,&nbsp;Hongkui Dong ,&nbsp;Fujie Jiang ,&nbsp;Wen Zhao ,&nbsp;Yingqi Feng ,&nbsp;Liu Cao ,&nbsp;Xuanwei Liu","doi":"10.1016/j.gr.2025.02.010","DOIUrl":"10.1016/j.gr.2025.02.010","url":null,"abstract":"<div><div>The West Kunlun piedmont tectonic belt was formed by the collision and accretion of the West Kunlun orogenic belt and the Tarim Craton. Its sedimentary record captures the processes of basin-mountain interactions, making it an excellent region for studying the formation of orogenic belts and the evolutionary history of the Tethys Ocean. Despite extensive research on the geological evolution of the West Kunlun orogenic belt by previous scholars, there remains considerable uncertainty regarding the initiation and termination times of oceanic crust subduction to the eventual closure for both the Proto-Tethys Ocean and the Paleo-Tethys Ocean in this region, as well as the temporal continuity between these two processes. This study obtained 703 detrital zircons with concordant ages from 9 core samples of Devonian to Cretaceous sandstones from 5 wells in the West Kunlun piedmont tectonic belt. Additionally, published detrital zircon data from the surrounding areas of the West Kunlun orogenic belt were collected from other studies for comparative analysis. The results indicate that the provenance of the piedmont tectonic belt during the Permian and Cretaceous periods primarily originated from the adjacent South and North Kunlun terranes. In contrast, during the Jurassic period, the provenance shifted to the Tianshuihai terrane. We infer that this change in sediment source was related to the closure of the Paleo-Tethys Ocean in the Late Triassic. Synthesizing previous research on magmatic rocks in the West Kunlun region, we identified two discontinuous orogenic cycles within the West Kunlun orogenic belt, which span from the Proto-Tethys Ocean to the Paleo-Tethys Ocean: the 560 Ma-380 Ma Proto-Tethys orogenic cycle and the 340 Ma–190 Ma Paleo-Tethys orogenic cycle. There was a distinct hiatus between the two cycles, during which the subdued volcanic activity during a tectonically stable period resulted in a minimal zircon record.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"141 ","pages":"Pages 213-227"},"PeriodicalIF":7.2,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143551944","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}