Precambrian Research最新文献

{"title":"Neoproterozoic three-stage evolution in the northern margin of the lower Yangtze Block: Evidence from low-grade metamorphic sedimentary sequence in the Zhangbaling uplift","authors":"Xing Wei ,&nbsp;Shuang-ying Li ,&nbsp;Zhen-sheng Li ,&nbsp;Dong-Dong Yang ,&nbsp;Song Wang ,&nbsp;Wei Xie ,&nbsp;Bo Hu ,&nbsp;Min Li ,&nbsp;Cheng Cheng","doi":"10.1016/j.precamres.2025.107982","DOIUrl":"10.1016/j.precamres.2025.107982","url":null,"abstract":"<div><div>Neoproterozoic magmatic and sedimentary records in Yangtze Block are widely used to investigate the assembly and breakup processes of the supercontinent Rodinia. However, the tectonic setting of the Yangtze Block and its paleoposition within Rodinia still remain highly controversial. To address these issues, we conducted an integrated provenance study—combining field observations, whole-rock geochemistry, heavy mineral analysis, and detrital zircon U–Pb–Hf isotopes—on the well-preserved Cryogenian to Ediacaran sedimentary sequence in the Zhangbaling uplift along the northern margin of the lower Yangtze Block. Results indicate that the Zhougang and Sujiawan formations as Cryogenian units (ca. 700–635 Ma) and the Beijiangjun and Doushantuo formations as Ediacaran units (ca. 600–565 Ma). The Cryogenian deposits were derived from the underlying late Tonian volcanics and were deposited in a back-arc setting. Conversely, the Ediacaran sediments were formed in a cratonic rift setting, with the interior of the lower Yangtze Block as the primary source and the early Ediacaran arc as the secondary one. Notably, the trace element characteristics of the Neoproterozoic detrital zircons reveal two stages of arc-related magmatism along the northern margin of the lower Yangtze Block, with peak ages around 827–820 Ma and 781–757 Ma. This evidence, combined with the comparison with the northwestern Yangtze, indicates three evolutionary stages: two-stage island arcs during the Tonian, a residual back-arc basin during the Cryogenian, and a passive continental margin during the Ediacaran. The Neoproterozoic tectonics and evolutionary processes of the northern Yangtze Block suggest its peripheral position within Rodinia and offer new constraints for Neoproterozoic supercontinental reconstructions.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"433 ","pages":"Article 107982"},"PeriodicalIF":3.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145694795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Possible dickinsoniomorphs from the latest Ediacaran Nama Group, southern Namibia","authors":"Brandt M. Gibson ,&nbsp;Joshua H.F.L. Davies ,&nbsp;Simon A.F. Darroch ,&nbsp;Ajani Bissick ,&nbsp;Andrea Boscaini ,&nbsp;Galen P. Halverson ,&nbsp;Frederick J. Hilgen ,&nbsp;Peter R. Liberty ,&nbsp;Johnathan A. Sorrentino ,&nbsp;Bianca R. Spiering ,&nbsp;Patricia Vickers-Rich ,&nbsp;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":"2026-02-01","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}

{"title":"The Lac Opasatica igneous complex: An autochthonous Abitibi greenstone basement to the Pontiac Subprovince","authors":"T.A. Ducharme ,&nbsp;C. Guilmette,&nbsp;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":"2026-02-01","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}

{"title":"Distribution and petrogenesis of 1.62 Ga Taishan mafic dyke swarm in the North China Craton: Implications for supercontinental geodynamics","authors":"Chong Wang ,&nbsp;Peng Peng ,&nbsp;Xin Chen ,&nbsp;Xu Liu ,&nbsp;Xinping Wang ,&nbsp;Bisheng Xu ,&nbsp;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 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)<em>_N</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_Nd(<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":"2026-02-01","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}

{"title":"Tectonic evolution of the Central Qilian Block and its reconstruction within Rodinia: insights from Neoproterozoic metasedimentary rocks in the South Qilian Belt, NW China","authors":"Yu Qin ,&nbsp;Yunpeng Dong ,&nbsp;Qiao Feng ,&nbsp;Xiaoli Zhang ,&nbsp;Qi Wang","doi":"10.1016/j.precamres.2025.107991","DOIUrl":"10.1016/j.precamres.2025.107991","url":null,"abstract":"<div><div>The overall paleogeographic configuration of the Rodinia supercontinent has been well defined, but the paleo-position of some East Asian microcontinents remains ambiguous, such as the Central Qilian Block (CQB), hindering robust Rodinia reconstruction. The South Qilian Belt separates the CQB from the Quanji Block, and preserves abundant Neoproterozoic rocks, providing a critical window for elucidating the Neoproterozoic tectonic evolution of the CQB and its paleo-position in Rodinia. Herein, this study focuses on the Neoproterozoic metasedimentary rocks in the South Qilian Belt and conducts integrated field geology, petrography, whole-rock geochemistry, and zircon U–Pb–Hf isotopes and trace element analyses. Our new data reveal that the Neoproterozoic metasedimentary rocks were likely deposited in a back-arc basin during 820–713 Ma. Provenance analysis indicates dominant derivation from the Neoproterozoic continental arc unit in the CQB and the Paleoproterozoic basement rocks in the Quanji Block. Synthesis of these results with existing data supports a model wherein protracted Neoproterozoic oceanic subduction coupled with associated back-arc extension probably drove the detachment of the CQB from the Quanji Block at the periphery of Rodinia. Based on compiled detrital zircon U–Pb–Hf isotopes and geological records from major Rodinia blocks, we propose that the unified Qilian-Quanji-Qaidam Block (QQB) was situated between Tarim and South China. The composite Tarim-QQB-South China probably occupied the northern periphery of the Rodinia supercontinent, adjacent to North India-East Antarctica. Our study links the subduction zone along the northern margin of the CQB to the circum-Rodinia subduction-accretion system, highlighting the crucial role of plate-boundary processes in facilitating lithospheric extension and thereby contributing to the breakup of Rodinia.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"433 ","pages":"Article 107991"},"PeriodicalIF":3.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145749411","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Autochthonous crustal growth and sedimentation in the Superior Province recorded by xenocrystic and detrital zircon","authors":"J.W.D. Strong ,&nbsp;A.R. Cruden ,&nbsp;P.A. Cawood ,&nbsp;X. Wang ,&nbsp;P. Hollings ,&nbsp;D. Li ,&nbsp;K. Ross ,&nbsp;A.J.M. Lalonde ,&nbsp;J. Marsh ,&nbsp;J.M. Simmons","doi":"10.1016/j.precamres.2025.107980","DOIUrl":"10.1016/j.precamres.2025.107980","url":null,"abstract":"<div><div>Analysis of U-Pb/Lu-Hf isotopes in zircon populations from plutonic orthogneisses and metasedimentary rocks are used to constrain the Paleoarchean to Neoarchean tectonic processes that led to Neoarchean cratonization of the western Superior Province. Plutonic orthogneisses from the North Caribou and western Wabigoon terranes assimilated varying degrees of Paleoarchean to Mesoarchean protoliths in the form of xenocrystic zircon, which indicate that the dominantly juvenile Neoarchean western Wabigoon and juvenile Mesoarchean to Neoarchean North Caribou terranes formed in association with an older Paleoarchean to Mesoarchean crustal basement. In addition, metasedimentary rocks from the North Caribou, English River, Winnipeg River, Wabigoon and Quetico terranes have detrital zircon age spectra and Hf(t) isotope compositions indicating ubiquitous availability of similar sedimentary sources across the western Superior Province during the Neoarchean. Collectively, the xenocrystic and detrital zircon evidence from the western Superior Province supports autochthonous growth of all terranes while the Neoarchean pre/<em>syn</em>-tectonic basins accepted detritus from widely available Mesoarchean to Neoarchean sources.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"433 ","pages":"Article 107980"},"PeriodicalIF":3.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145694344","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Late Neoproterozoic development of the Nanhua Basin and implications for assembly of the South China Block","authors":"Yuan Xia ,&nbsp;Yajun Xu ,&nbsp;Peter A. Cawood ,&nbsp;Jiahui Zhang ,&nbsp;Jie Zhang","doi":"10.1016/j.precamres.2025.107989","DOIUrl":"10.1016/j.precamres.2025.107989","url":null,"abstract":"<div><div>Whole rock geochemistry, detrital zircon U-Pb geochronology, and Lu-Hf isotopic data from late Neoproterozoic strata within the Nanhua Basin, South China, provide crucial insights into the amalgamation history of the Yangtze and Cathaysia blocks. Strata from the central part of the basin (Xinyu and Ji’an regions) overlie the western margin of the Cathaysia Block and consist of, from bottom to top, the Shenshan, Kuli, Shangshi, Xiafang, Bali, and Laohutang formations. Detrital zircon age spectra of the samples from the Shenshan Formation to the Xiafang Formation show a unimodal distribution around 770–700 Ma. In contrast, samples from the overlying Xiafang and Bali formations are dominated by zircons with ages in the range 1100–900 Ma, along with some aged 2600–2400 Ma, 1950–1750 Ma, 1500–1300 Ma, and ca. 688 Ma. Based on the ages of the youngest detrital zircons and regional stratigraphic correlations with the well-established glacial and interglacial strata in the Jinping-Congjiang region, the maximum depositional ages of the units are 717 Ma for the Shenshan Formation, 717–690 Ma for the Kuli to Shangshi formations, between 690 Ma and 635 Ma for the Xiafang Formation, between 635 Ma and 550 Ma for the Bali Formation, and post-550 Ma for the Laohutang Formation. U-Pb ages, Lu-Hf isotopic compositions, and whole-rock geochemistry data indicate that detrital zircons with ages from 770 Ma to 700 Ma were sourced from the coeval arc-related magmatic rocks along the northern margin of the Yangtze Block. The transport of sediments across the Yangtze and Cathaysia blocks suggests that the Nanhua Basin is a late Tonian to Cryogenian intracontinental basin, and the amalgamation of the Yangtze and Cathaysia blocks occurred before the late Tonian. Older zircons aged 1100–900 Ma, 1500–1300 Ma, 1950–1750 Ma, and 2600–2400 Ma came from the Gondwana continent. Synchronous sediment input into the Nanhua Basin from both the northern margin of the Yangtze Block volcanic arc and Gondwana sources during the late Tonian to Cryogenian, suggesting a back-arc tectonic setting developed along the northern margin of East Gondwana. Integration with previous geochronological data, the two episodic propagation processes of Gondwana-derived sediments toward the northeast of the Nanhua Basin in the late Cryogenian and Cambrian are likely related to pulses of crustal thickening and topographic uplift during the assembly of Gondwana.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"433 ","pages":"Article 107989"},"PeriodicalIF":3.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145694796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Revisiting the Fennoscandia–Sarmatia Paleoproterozoic Suture: evidence from the PolandSPAN™ seismic survey and integrated geophysical modelling","authors":"Mateusz Mikołajczak ,&nbsp;Stanisław Mazur ,&nbsp;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":"2026-02-01","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}

{"title":"A shallow, subduction-modified continental lithospheric mantle source for the Palaeoproterozoic Hart Dolerite, Western Australia","authors":"Alex E. Eves ,&nbsp;Rob R. Ramsay ,&nbsp;Anthony I.S. Kemp ,&nbsp;Roland Maas ,&nbsp;Laure Martin ,&nbsp;Marco L. Fiorentini","doi":"10.1016/j.precamres.2025.107978","DOIUrl":"10.1016/j.precamres.2025.107978","url":null,"abstract":"<div><div>Petrogenetic models for continental mafic provinces typically invoke either plume-derived asthenospheric melting or subduction-related enrichment of the continental lithospheric mantle (CLM). Which of these models applies for the ca. 1793 Ma Hart Dolerite of the Kimberley Block (North Australian Craton), a sill-dominated and regionally extensive suite, has long been debated. To test these competing models, the petrogenesis of the Hart Dolerite is evaluated with new field observations, drill-core logging, whole-rock geochemistry, and Sr–Nd–Pb–O isotopes. Samples with liquid-like bulk compositions define transitional tholeiitic–calc-alkaline trends with arc-like HFSE depletions and modest LREE–LILE enrichment. Unaltered rocks yield εNd_i from −0.8 to +0.8 and ⁸⁷Sr/⁸⁶Sr_i of 0.7028–0.7035; Pb isotopes are heterogeneous and non-diagnostic. Interstitial quartz records δ¹⁸O = +11.4 to +13.2 ‰, and with no evidence for crustal assimilation, are interpreted as reflecting a modestly elevated lithospheric mantle source. Stratigraphic constancy of Sr–Nd isotopes across a ∼500 m-thick sill, together with the absence of covariation between isotope ratios and fractionation-sensitive trace elements, argues against assimilation–fractional crystallisation processes. Constraints from regional geophysics, supported by xenolith and xenocryst observations, place melting within spinel-facies CLM at ∼2–3 GPa (∼60–90 km), where hydrous peridotite crosses the solidus during post-orogenic extension. A subduction-modified CLM reservoir that became metasomatised and then reworked during later 1870 – 1805 Ma orogenic cycles was reactivated at 1793 Ma to yield low-degree melts that were emplaced at shallow crustal levels. In this geodynamic context, coeval uplift, radial dyke swarms, and OIB-like chemistry are absent. The Hart Dolerite therefore documents intraplate magmatism generated without plume input, produced instead by decompression melting of preconditioned mantle lithosphere. This framework provides a testable template for modest-volume, sill-dominated provinces, emphasising lithospheric memory and the coupling of metasomatism with later extensional triggers.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"433 ","pages":"Article 107978"},"PeriodicalIF":3.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145798578","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A lost fragment of Siderian oceanic and juvenile arc crust preserved in the Borborema province, northeast Brazil","authors":"Paula F.T. Alvim,&nbsp;Elton L. Dantas,&nbsp;Reinhardt A. Fuck,&nbsp;Alanielson C.D. Ferreira","doi":"10.1016/j.precamres.2025.107979","DOIUrl":"10.1016/j.precamres.2025.107979","url":null,"abstract":"<div><div>The Tectono-Magmatic Lull (TML), or Siderian Quiet Interval, represents a pivotal stage in Earth’s history between 2.36 and 2.23 Ga, marked by a global reduction in tectonic activity, magmatism, and crustal growth. It features a global decline in tectonic activity, magmatism, and crustal formation, creating a major gap in the geotectonic record worldwide. To investigate this interval, detailed field mapping, petrography, U–Pb zircon geochronology, whole-rock geochemistry, and Sm–Nd isotopic analyses were carried out on rocks from the Santa Luzia Sequence in the Lajes Block, Borborema Province (NE Brazil). The sequence, consisting of amphibolites, calc-silicate rocks, and hornblendites, yields U–Pb zircon ages ranging from 2.48 to 2.31 Ga, along with an older amphibolite dated at 3.14 Ga. Whole-rock geochemical patterns exhibit pronounced negative Nb, Ta, and Ti anomalies, indicating oceanic and arc-related affinities. Sm–Nd isotopic data reinforce this framework: juvenile lithotypes show positive εNd_(t) values and Nd T_DM ages of 2.36–2.12 Ga, whereas a subset of amphibolites preserves significantly older Nd T_DM ages (3.97–2.62 Ga), revealing an Archean crustal substrate predating arc assembly. Coeval plutonic rocks document continued crustal reworking and juvenile addition from the Siderian into the Rhyacian. Spatial, geochemical, and isotopic relationships indicate that the calc-silicate rocks formed through metasomatic alteration of mafic precursors. Despite later metasomatic and hydrothermal overprints that produced LREE enrichment and fluid-driven metamorphism, the primary magmatic signatures remain well preserved. Collectively, these results show that subduction-related magmatism persisted locally in Borborema, in contrast with the TML and tectonic shutdown theories.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"433 ","pages":"Article 107979"},"PeriodicalIF":3.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145749403","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}