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.
{"title":"A window on the amalgamation of Western Gondwana: Geological history of the Ouaddaï massif (E. Chad)","authors":"Alexis Plunder , Olivier Blein , Moussa Isseini , Issaka Ousman Al-Gadam , Matthieu Chevillard , Emanuel Djedouboum , Philippe Lach , Abdeltif Lahfid , Jérémie Melleton , Olivier Rouzeau , 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":"2026-01-05","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}
Pub Date : 2026-01-03DOI: 10.1016/j.precamres.2025.107992
Xin Wang , Xingliang Zhang , Tao Dai , Wei Liu , Yuan Zhang , Luoyang Li
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’.
{"title":"New occurrence of a postglacial Ediacaran macrofossil assemblage from North China and its evolutionary implication","authors":"Xin Wang , Xingliang Zhang , Tao Dai , Wei Liu , Yuan Zhang , 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":"2026-01-03","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}
Pub Date : 2026-01-02DOI: 10.1016/j.precamres.2025.108003
Taghi Shirzad , Marcelo Assumpção , Marcelo B. Bianchi , Bruno Collaço , Fernando Alkmim , Dionísio U. Carlos , Luciano Assis , Maximiliano Simão
The Quadrilátero Ferrífero (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 H-k stacking of receiver functions. Other stations in the São Francisco craton, outside the QF, show intermediate thicknesses of 36–39 km. Bulk crustal Vp/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.
{"title":"Crustal structure in the Quadrilátero Ferrífero mineral province, SE Brazil: differentiating preserved and reworked Archean crust","authors":"Taghi Shirzad , Marcelo Assumpção , Marcelo B. Bianchi , Bruno Collaço , Fernando Alkmim , Dionísio U. Carlos , Luciano Assis , 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":"2026-01-02","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}
Pub Date : 2025-12-31DOI: 10.1016/j.precamres.2025.107998
Guyue Hu , Chunlian Wang , Kuidong Zhao , Qian Li , Yanhe Li , Xinsheng Sun , Jun Zheng , Kunming Wang , Jianghua Gong , Peng Li , Yue Zhao
Many Paleoproterozoic borate deposits are hosted within the lower units of the volcanic–sedimentary sequence (ca. 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 δ13C 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 δ26Mg 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.
{"title":"Marine evaporitic borate mineralization during the Lomagundi–Jatuli Event, Liaodong Peninsula, northeast China","authors":"Guyue Hu , Chunlian Wang , Kuidong Zhao , Qian Li , Yanhe Li , Xinsheng Sun , Jun Zheng , Kunming Wang , Jianghua Gong , Peng Li , 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><sup>13</sup>C 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><sup>26</sup>Mg 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":"2025-12-31","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}
Pub Date : 2025-12-26DOI: 10.1016/j.precamres.2025.108002
T.A. Ducharme , C. Guilmette, J. Darveau
Basement underlying the Archean metasedimentary belts of the Superior Province is rarely exposed, but key to understanding the tectonic provenance of these basins. The Pontiac Subprovince is one such belt dominated by turbiditic clastic rocks and minor volumes of intrusive and extrusive igneous rock. Tectonic models for the Pontiac Subprovince propose that it represents either a paleo-accretionary wedge or an extensional basin host to authigenic volcanism. Both models consider the supracrustal sequence to overlie older tonalite-trondhjemite-granodiorite (TTG) gneisses, the Opasatica Gneiss, classically interpreted as the regional basement. This work presents new zircon U-Pb data and bulk-rock geochemical data for Opasatica TTG gneisses and newly identified felsic volcanites situated structurally above the gneisses. Four felsic volcanic samples record zircon U-Pb ages of 2755 and 2740 Ma, coeval with the oldest volcanism in the adjacent Abitibi Subprovince. Four TTG gneiss samples yield U-Pb ages as young as 2690 Ma, coeval with TTG occurrences elsewhere in the Pontiac and Abitibi. Melanocratic components of the gneiss yield older ages of c. 2745 Ma, implying a composite intrusion history, and trace element systematics resembling those of the felsic volcanics imply these rocks may have been comagmatic. The revised geochronological framework of the Pontiac suggests it shares its magmatic history with the Abitibi Subprovince. We propose that the Pontiac is an integral component of the Abitibi Subprovince, obscured beneath a thick sedimentary cover. This interpretation of the Pontiac, and its record of syn-sedimentary magmatism, are incompatible with deposition of the Pontiac Group in an accretionary wedge environment.
{"title":"The Lac Opasatica igneous complex: An autochthonous Abitibi greenstone basement to the Pontiac Subprovince","authors":"T.A. Ducharme , C. Guilmette, J. Darveau","doi":"10.1016/j.precamres.2025.108002","DOIUrl":"10.1016/j.precamres.2025.108002","url":null,"abstract":"<div><div>Basement underlying the Archean metasedimentary belts of the Superior Province is rarely exposed, but key to understanding the tectonic provenance of these basins. The Pontiac Subprovince is one such belt dominated by turbiditic clastic rocks and minor volumes of intrusive and extrusive igneous rock. Tectonic models for the Pontiac Subprovince propose that it represents either a paleo-accretionary wedge or an extensional basin host to authigenic volcanism. Both models consider the supracrustal sequence to overlie older tonalite-trondhjemite-granodiorite (TTG) gneisses, the Opasatica Gneiss, classically interpreted as the regional basement. This work presents new zircon U-Pb data and bulk-rock geochemical data for Opasatica TTG gneisses and newly identified felsic volcanites situated structurally above the gneisses. Four felsic volcanic samples record zircon U-Pb ages of 2755 and 2740 Ma, coeval with the oldest volcanism in the adjacent Abitibi Subprovince. Four TTG gneiss samples yield U-Pb ages as young as 2690 Ma, coeval with TTG occurrences elsewhere in the Pontiac and Abitibi. Melanocratic components of the gneiss yield older ages of c. 2745 Ma, implying a composite intrusion history, and trace element systematics resembling those of the felsic volcanics imply these rocks may have been comagmatic. The revised geochronological framework of the Pontiac suggests it shares its magmatic history with the Abitibi Subprovince. We propose that the Pontiac is an integral component of the Abitibi Subprovince, obscured beneath a thick sedimentary cover. This interpretation of the Pontiac, and its record of <em>syn</em>-sedimentary magmatism, are incompatible with deposition of the Pontiac Group in an accretionary wedge environment.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"433 ","pages":"Article 108002"},"PeriodicalIF":3.2,"publicationDate":"2025-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840811","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 : 2025-12-24DOI: 10.1016/j.precamres.2025.108001
Mateusz Mikołajczak , Stanisław Mazur , Piotr Krzywiec
The East European Craton (EEC) consists of three major Precambrian domains—Fennoscandia, Sarmatia, and Volgo-Uralia—assembled during Paleoproterozoic continent–continent collisions. In eastern Poland, the crystalline basement comprises southwestern Fennoscandia and the adjoining northwestern margin of Sarmatia, separated by the Fennoscandia–Sarmatia Suture (FSS). Although its overall NE–SW orientation is well established, the precise location and internal structure of the FSS remain debated. In this study, we reassess the FSS in the Polish segment of the EEC using deep reflection seismic profiles from the PolandSPAN™ survey, combined with 2-D gravity and magnetic modelling and 3-D geophysical models of basement depth and crustal thickness. The results reveal a 100–120 km wide transitional zone, including of the Belarus–Podlasie Granulite and Okolovo Belts, characterized by anomalously dense and magnetically susceptible lithologies. These are interpreted as remnants of arc-related magmatic complexes, mafic igneous suites, or high-pressure metamorphic rocks, which are diagnostic of collisional sutures. Seismic imaging and geophysical modelling show that these anomalies extend through the entire crust, indicating a deeply rooted Paleoproterozoic collision. We conclude that the FSS does not correspond to a discrete fault but represents a diffuse, cryptic suture zone c. 100–120 km wide, comparable to those recognized in other Precambrian cratons. The northern and southern boundaries of the suture zone align with the margins of the Belarus–Podlasie Granulite and the Osnitsk–Mikashevichi Igneous Belts, respectively. Despite later overprinting, the FSS remains clearly detectable in integrated seismic and potential-field datasets. Its recognition as a wide collisional boundary provides new constraints on the tectonic evolution of the EEC.
{"title":"Revisiting the Fennoscandia–Sarmatia Paleoproterozoic Suture: evidence from the PolandSPAN™ seismic survey and integrated geophysical modelling","authors":"Mateusz Mikołajczak , Stanisław Mazur , Piotr Krzywiec","doi":"10.1016/j.precamres.2025.108001","DOIUrl":"10.1016/j.precamres.2025.108001","url":null,"abstract":"<div><div>The East European Craton (EEC) consists of three major Precambrian domains—Fennoscandia, Sarmatia, and Volgo-Uralia—assembled during Paleoproterozoic continent–continent collisions. In eastern Poland, the crystalline basement comprises southwestern Fennoscandia and the adjoining northwestern margin of Sarmatia, separated by the Fennoscandia–Sarmatia Suture (FSS). Although its overall NE–SW orientation is well established, the precise location and internal structure of the FSS remain debated. In this study, we reassess the FSS in the Polish segment of the EEC using deep reflection seismic profiles from the PolandSPAN™ survey, combined with 2-D gravity and magnetic modelling and 3-D geophysical models of basement depth and crustal thickness. The results reveal a 100–120 km wide transitional zone, including of the Belarus–Podlasie Granulite and Okolovo Belts, characterized by anomalously dense and magnetically susceptible lithologies. These are interpreted as remnants of arc-related magmatic complexes, mafic igneous suites, or high-pressure metamorphic rocks, which are diagnostic of collisional sutures. Seismic imaging and geophysical modelling show that these anomalies extend through the entire crust, indicating a deeply rooted Paleoproterozoic collision. We conclude that the FSS does not correspond to a discrete fault but represents a diffuse, cryptic suture zone c. 100–120 km wide, comparable to those recognized in other Precambrian cratons. The northern and southern boundaries of the suture zone align with the margins of the Belarus–Podlasie Granulite and the Osnitsk–Mikashevichi Igneous Belts, respectively. Despite later overprinting, the FSS remains clearly detectable in integrated seismic and potential-field datasets. Its recognition as a wide collisional boundary provides new constraints on the tectonic evolution of the EEC.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"433 ","pages":"Article 108001"},"PeriodicalIF":3.2,"publicationDate":"2025-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840812","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 : 2025-12-24DOI: 10.1016/j.precamres.2025.107995
Samir Debnath , Rohit Pandey , B. Belyatsky , David Chew , N.V. Chalapathi Rao , Mahendra Kumar Singh
A comprehensive study integrating field data, geochronology, mineral-whole rock geochemistry, and Sr-Nd-Pb-C-O isotope systematics is presented for a newly identified carbonatite-syenite complex from Gundlupete area, near the tectonic boundary between the Western Dharwar Craton and the Granulite Terrain, South India. The syenite, composed of alkali feldspar, albite, clinopyroxene, and biotite, yields a U-Pb titanite crystallisation age of 2590 ± 42 Ma. It displays shoshonitic geochemistry, with enriched LILE-LREE, depletion in Mg, Ni, Cr, HFSEs, and crust-like Th/Nb and Nb/U ratios. Initial εNd values (–1.4 to +1.0) and Nd model ages of 2.8–3.0 Ga indicate derivation from partial melts of Mesoarchean TTG crust, modified by fractional crystallisation. The intrusive carbonatite with a monazite U-Pb age of 2474 ± 27 Ma, is dominated by calcite, apatite, magnetite, monazite, amphibole, and phlogopite, and is enriched in Sr, REEs, and LILEs. Field and petrographic observations reveal distinctive apatite-magnetite-silicate banding within the carbonatite near the syenite contact, a feature inconsistent with simple magmatic differentiation. Instead, metasomatic reactions at the carbonatite-syenite interface likely produced antiskarn assemblages through wall-rock silica contamination. Sr-Nd-Pb isotope data shows time integrated higher Rb-Sr but low Sm/Nd and U/Pb ratios, tapping a chondritic to slightly enriched lithospheric mantle source modified by incorporation of small fractions of ancient subducted sediments into the source region. C–O isotope data show mantle-like δ18O, and the uniformly low δ13C (–10.23 to –9.41 ‰) further points to an organic component in the subducted sediments. Syenite and carbonatite magmatism relates to the Neoarchean amalgamation of the Dharwar Craton and Granulite Terrain, driven by northward subduction of the Dharwar ocean lithosphere. The syenite emplacement at 2.59 Ga is linked to the regional subduction-related magma underplating and crustal anatexis, while carbonatite intrusion at 2.47 Ga suggests a post-collisional magmatic pulse during terminal accretion near the Archean-Proterozoic boundary. The temporal, geochemical, and isotopic evolution recorded in the Gundlupete complex thus provides a robust archive of subduction-driven carbon recycling, mantle metasomatism, and crustal reworking processes at the Archean-Proterozoic transition.
{"title":"Carbonatite and syenite magmatism at the Archean-Proterozoic boundary in the Western Dharwar Craton, Southern India: Implication for petrogenesis, source characteristics and terrane geodynamics","authors":"Samir Debnath , Rohit Pandey , B. Belyatsky , David Chew , N.V. Chalapathi Rao , Mahendra Kumar Singh","doi":"10.1016/j.precamres.2025.107995","DOIUrl":"10.1016/j.precamres.2025.107995","url":null,"abstract":"<div><div>A comprehensive study integrating field data, geochronology, mineral-whole rock geochemistry, and Sr-Nd-Pb-C-O isotope systematics is presented for a newly identified carbonatite-syenite complex from Gundlupete area, near the tectonic boundary between the Western Dharwar Craton and the Granulite Terrain, South India. The syenite, composed of alkali feldspar, albite, clinopyroxene, and biotite, yields a U-Pb titanite crystallisation age of 2590 ± 42 Ma. It displays shoshonitic geochemistry, with enriched LILE-LREE, depletion in Mg, Ni, Cr, HFSEs, and crust-like Th/Nb and Nb/U ratios. Initial εNd values (–1.4 to +1.0) and Nd model ages of 2.8–3.0 Ga indicate derivation from partial melts of Mesoarchean TTG crust, modified by fractional crystallisation. The intrusive carbonatite with a monazite U-Pb age of 2474 ± 27 Ma, is dominated by calcite, apatite, magnetite, monazite, amphibole, and phlogopite, and is enriched in Sr, REEs, and LILEs. Field and petrographic observations reveal distinctive apatite-magnetite-silicate banding within the carbonatite near the syenite contact, a feature inconsistent with simple magmatic differentiation. Instead, metasomatic reactions at the carbonatite-syenite interface likely produced antiskarn assemblages through wall-rock silica contamination. Sr-Nd-Pb isotope data shows time integrated higher Rb-Sr but low Sm/Nd and U/Pb ratios, tapping a chondritic to slightly enriched lithospheric mantle source modified by incorporation of small fractions of ancient subducted sediments into the source region. C–O isotope data show mantle-like δ<sup>18</sup>O, and the uniformly low δ<sup>13</sup>C (–10.23 to –9.41 ‰) further points to an organic component in the subducted sediments. Syenite and carbonatite magmatism relates to the Neoarchean amalgamation of the Dharwar Craton and Granulite Terrain, driven by northward subduction of the Dharwar ocean lithosphere. The syenite emplacement at 2.59 Ga is linked to the regional subduction-related magma underplating and crustal anatexis, while carbonatite intrusion at 2.47 Ga suggests a post-collisional magmatic pulse during terminal accretion near the Archean-Proterozoic boundary. The temporal, geochemical, and isotopic evolution recorded in the Gundlupete complex thus provides a robust archive of subduction-driven carbon recycling, mantle metasomatism, and crustal reworking processes at the Archean-Proterozoic transition.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"433 ","pages":"Article 107995"},"PeriodicalIF":3.2,"publicationDate":"2025-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840814","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 : 2025-12-23DOI: 10.1016/j.precamres.2025.107999
Chong Wang , Peng Peng , Xin Chen , Xu Liu , Xinping Wang , Bisheng Xu , Binghe Li
The spatial–temporal distribution of mantle-derived mafic magmatism provides crucial constraints on global/regional geodynamics, particularly rifting to breakup processes. This study investigates the 1.62 Ga Taishan mafic dyke swarm in the North China Craton, extending its recognized distribution through new field identifications in the Western Shandong Province. High-precision SIMS baddeleyite dating constrains the emplacement age to 1604–1617 Ma, confirming widespread magmatic activity during this period. Geochemical analyses reveal the dykes are tholeiitic characterized by SiO2 (48.1–52.0 wt%), MgO (4.3–7.4 wt%), total Fe2O3 (10.9–17.2 wt%), TiO2 (0.93–1.73 wt%), Al2O3 (12.1–17.6 wt%), CaO (2.3–5.4 wt%), and Mg numbers of 45–60. Systematic trends in major elements indicate fractional crystallization dominated by plagioclase and Fe–Ti oxides. The dykes are enriched in light rare earth element and can be divided into two groups based on (La/Yb)N ratios (2.5–3.4 and 4.8–6.0). Their trace element patterns are characterized by positive K anomalies and depletions in Nb–Ta and P. The εNd(t) values range from –3.6 to +1.6. Geochemically, the Taishan dykes resemble the subalkaline basalts of the coeval Dahongyu Formation in the Yanliao rift, which are spatially associated with ∼ 1625 Ma OIB-type alkaline volcanics. We interpret that these magmatic suits originated from a common plume-related event, where: (a) the tholeiitic dykes and subalkaline basalts were derived from higher-degree melting of metasomatized subcontinental lithospheric mantle, and (b) alkaline volcanics formed by lower-degree melting of an asthenosphere or plume source. Globally, the contemporaneous Melville Bugt mafic dyke swarm (Greenland) and Biryusa mafic sills (Siberia) share notable petrological and geochemical characteristics with the Taishan swarm, supporting a possible geodynamic linkage among these cratons within the supercontinent Columbia/Nuna framework.
{"title":"Distribution and petrogenesis of 1.62 Ga Taishan mafic dyke swarm in the North China Craton: Implications for supercontinental geodynamics","authors":"Chong Wang , Peng Peng , Xin Chen , Xu Liu , Xinping Wang , Bisheng Xu , Binghe Li","doi":"10.1016/j.precamres.2025.107999","DOIUrl":"10.1016/j.precamres.2025.107999","url":null,"abstract":"<div><div>The spatial–temporal distribution of mantle-derived mafic magmatism provides crucial constraints on global/regional geodynamics, particularly rifting to breakup processes. This study investigates the 1.62 Ga Taishan mafic dyke swarm in the North China Craton, extending its recognized distribution through new field identifications in the Western Shandong Province. High-precision SIMS baddeleyite dating constrains the emplacement age to 1604–1617 Ma, confirming widespread magmatic activity during this period. Geochemical analyses reveal the dykes are tholeiitic characterized by SiO<sub>2</sub> (48.1–52.0 wt%), MgO (4.3–7.4 wt%), total Fe<sub>2</sub>O<sub>3</sub> (10.9–17.2 wt%), TiO<sub>2</sub> (0.93–1.73 wt%), Al<sub>2</sub>O<sub>3</sub> (12.1–17.6 wt%), CaO (2.3–5.4 wt%), and Mg numbers of 45–60. Systematic trends in major elements indicate fractional crystallization dominated by plagioclase and Fe–Ti oxides. The dykes are enriched in light rare earth element and can be divided into two groups based on (La/Yb)<em><sub>N</sub></em> ratios (2.5–3.4 and 4.8–6.0). Their trace element patterns are characterized by positive K anomalies and depletions in Nb–Ta and P. The ε<sub>Nd</sub>(<em>t</em>) values range from –3.6 to +1.6. Geochemically, the Taishan dykes resemble the subalkaline basalts of the coeval Dahongyu Formation in the Yanliao rift, which are spatially associated with ∼ 1625 Ma OIB-type alkaline volcanics. We interpret that these magmatic suits originated from a common plume-related event, where: (a) the tholeiitic dykes and subalkaline basalts were derived from higher-degree melting of metasomatized subcontinental lithospheric mantle, and (b) alkaline volcanics formed by lower-degree melting of an asthenosphere or plume source. Globally, the contemporaneous Melville Bugt mafic dyke swarm (Greenland) and Biryusa mafic sills (Siberia) share notable petrological and geochemical characteristics with the Taishan swarm, supporting a possible geodynamic linkage among these cratons within the supercontinent Columbia/Nuna framework.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"433 ","pages":"Article 107999"},"PeriodicalIF":3.2,"publicationDate":"2025-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840813","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 : 2025-12-22DOI: 10.1016/j.precamres.2025.107981
Brandt M. Gibson , Joshua H.F.L. Davies , Simon A.F. Darroch , Ajani Bissick , Andrea Boscaini , Galen P. Halverson , Frederick J. Hilgen , Peter R. Liberty , Johnathan A. Sorrentino , Bianca R. Spiering , Patricia Vickers-Rich , Marc Laflamme
The late Neoproterozoic Ediacaran Period is marked by one or more pulses of biotic turnover thought to represent intervals of global extinction, and which removed several enigmatic groups of Precambrian metazoans over a ∼10-million-year interval in the lead-up to the Cambrian. Here, we report the discovery of putative dickinsoniomorph ‘survivors’ from the Nama Group of southern Namibia, including specimens preserved in place directly above an ash bed dated in this study at 538.97 ± 0.21 Ma, and thus within error of the currently defined Ediacaran-Cambrian boundary. Some key features are poorly preserved and thus identification at this point is not definitive; however, following comparisons with a wide variety of other Ediacaran taxa and abiotic structures, we argue that interpretation as dickinsonimorph body fossils is most parsimonious. More material is undoubtedly required; however, if supported these fossils would represent the youngest dickinsoniomorph fossils found anywhere in the world, showing that this group survived the first pulse of Ediacaran extinction at ∼550 Ma, and necessitating a re-evaluation of hypothesized drivers of late Ediacaran biotic turnover events. We suggest that these new fossil discoveries are consistent with recent models of selective extinction driven by pulses of ecological stress, reinforcing the inference that environmental perturbations were likely a crucial influence on patterns of early animal evolution prior to the main phase of the Cambrian explosion.
{"title":"Possible dickinsoniomorphs from the latest Ediacaran Nama Group, southern Namibia","authors":"Brandt M. Gibson , Joshua H.F.L. Davies , Simon A.F. Darroch , Ajani Bissick , Andrea Boscaini , Galen P. Halverson , Frederick J. Hilgen , Peter R. Liberty , Johnathan A. Sorrentino , Bianca R. Spiering , Patricia Vickers-Rich , Marc Laflamme","doi":"10.1016/j.precamres.2025.107981","DOIUrl":"10.1016/j.precamres.2025.107981","url":null,"abstract":"<div><div>The late Neoproterozoic Ediacaran Period is marked by one or more pulses of biotic turnover thought to represent intervals of global extinction, and which removed several enigmatic groups of Precambrian metazoans over a ∼10-million-year interval in the lead-up to the Cambrian. Here, we report the discovery of putative dickinsoniomorph ‘survivors’ from the Nama Group of southern Namibia, including specimens preserved in place directly above an ash bed dated in this study at 538.97 ± 0.21 Ma, and thus within error of the currently defined Ediacaran-Cambrian boundary. Some key features are poorly preserved and thus identification at this point is not definitive; however, following comparisons with a wide variety of other Ediacaran taxa and abiotic structures, we argue that interpretation as dickinsonimorph body fossils is most parsimonious. More material is undoubtedly required; however, if supported these fossils would represent the youngest dickinsoniomorph fossils found anywhere in the world, showing that this group survived the first pulse of Ediacaran extinction at ∼550 Ma, and necessitating a re-evaluation of hypothesized drivers of late Ediacaran biotic turnover events. We suggest that these new fossil discoveries are consistent with recent models of selective extinction driven by pulses of ecological stress, reinforcing the inference that environmental perturbations were likely a crucial influence on patterns of early animal evolution prior to the main phase of the Cambrian explosion.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"433 ","pages":"Article 107981"},"PeriodicalIF":3.2,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840810","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 : 2025-12-19DOI: 10.1016/j.precamres.2025.107996
Lisha Hu , Jie Yang , Yuansheng Du , Zuozhen Han , Hongwei Kuang , Yongqing Liu , Chao Han , Yi Zhang , Wei Jin , Le Wan
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 εHf(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.
{"title":"South China in the Rodinia-Gondwana transition: Constrains from the Ediacaran Doushantuo Formation of the north Yangtze Block","authors":"Lisha Hu , Jie Yang , Yuansheng Du , Zuozhen Han , Hongwei Kuang , Yongqing Liu , Chao Han , Yi Zhang , Wei Jin , 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<sub>Hf</sub>(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":"2025-12-19","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}
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