Precambrian Research最新文献

{"title":"Vestige of Paleoproterozoic metamorphism in the Trivandrum block, India: New evidence from zircon U-Pb ages","authors":"Yuquan Wang ,&nbsp;Bo Liu ,&nbsp;Mingguo Zhai ,&nbsp;Hailong He ,&nbsp;K. Sajeev ,&nbsp;P.M. George","doi":"10.1016/j.precamres.2025.107957","DOIUrl":"10.1016/j.precamres.2025.107957","url":null,"abstract":"<div><div>The Trivandrum Block in India has long been regarded as the central part of the Pan-African orogenic event. However, several previous studies suggested a potential presence of a large-scale magmatic-metamorphic event in this area during the Paleoproterozoic. To better understand the Paleoproterozoic geological evolution of this terrain, we conducted detailed mineral inclusion studies on three gneiss samples (Grt-Bt gneiss, leucogneiss, Grt-Sil-Crd gneiss) at the Kulappara quarry in the Trivandrum Block, combined with zircon morphology and SIMS U-Pb dating. The Grt-Bt gneiss is the enclave in the Grt-Sil-Crd gneiss. The dating results of zircon with metamorphic features from both samples are at ∼2.0 Ga. In the zircon grains of the Grt-Sil-Crd gneiss sample, sillimanite inclusions were discovered, within the ∼2.0 Ga zircon. The leucogneiss is interbedded with the Grt-Sil-Crd gneiss, and occasionally pinching out into the Grt-Sil-Crd gneiss. Combined with the dating results of zircon, which show characteristics formed during anatexis, are at the age of ∼1.98 Ga in the leucogneiss, we suggest that an intense metamorphic event likely occurred at around 2.0 Ga and the metamorphic grade may once reach the upper amphibolite or even up to the granulite facies. High-grade metamorphic rocks in the Paleoproterozoic are widely distributed in many ancient blocks worldwide, and this period is an important stage of the transition to the global subduction zone network of the Earth. Therefore, the discovery of traces of high-grade metamorphism in the Trivandrum Block likely indicates the involvement of this region in the global tectonic evolution during the Paleoproterozoic. There are also a plenty of zircon dating results concentrated around 580–530 Ma in the studied samples. This shows us that the Paleoproterozoic event was subsequently overprinted by the intense Neoproterozoic–Cambrian HT–UHT metamorphism, suggesting a long-lived feature for this Pan-African tectonothermal event.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"431 ","pages":"Article 107957"},"PeriodicalIF":3.2,"publicationDate":"2025-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145419274","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 complicated relationships between early eukaryotic evolution and the oxidation state of Earth’s surface environments","authors":"Dongdong Li ,&nbsp;Genming Luo ,&nbsp;Bing Shen ,&nbsp;Shuhai Xiao","doi":"10.1016/j.precamres.2025.107960","DOIUrl":"10.1016/j.precamres.2025.107960","url":null,"abstract":"<div><div>Persistently low atmospheric oxygen levels (<em>p</em>O₂) have been proposed as a primary factor contributing to the delay between the emergence of total-group eukaryotes in the late Paleoproterozoic and the divergence of crown-group eukaryotes at the Meso-Neoproterozoic transition. However, the temporal relationship between <em>p</em>O₂ fluctuations and the early evolution of eukaryotes, e.g., emergence and diversification, remains uncertain. In this study, we compiled both published and newly acquired data on redox conditions and fossil occurrences spanning the late Paleoproterozoic to the early Neoproterozoic. Based on the compilation of rare earth element data in shallow-water carbonates from this interval, we quantified atmospheric <em>p</em>O₂ using thermodynamics-based modeling. Our results suggest that <em>p</em>O₂ generally increased from low values of ≤ 1 % of the present atmospheric level (PAL) in the late Paleoproterozoic to ∼5–10 % PAL in the mid-Mesoproterozoic, before declining to ∼1 % PAL at the Meso-Neoproterozoic transition. Comparison with fossil records indicates that early stem-group eukaryotes in the Paleo-Mesoproterozoic emerged under low <em>p</em>O₂ conditions, that the mid-Mesoproterozoic rise in <em>p</em>O₂ did not lead to increased diversity, and that crown-group diversification at the Meso-Neoproterozoic transition occurred during a period of declining <em>p</em>O₂. Together, these observations show that atmospheric oxygen and early eukaryotic evolution did not consistently covary, highlighting that the complicated interactions among oxygen content, nutrient supply, temperature, and biotic factors shaped the early eukaryotic evolution in the mid-Proterozoic.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"431 ","pages":"Article 107960"},"PeriodicalIF":3.2,"publicationDate":"2025-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145419273","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":"Growth and disparity of form in the Ediacaran genus Charnia, with description of Charnia brasieri sp. nov. from the Ediacaran of Avalonia","authors":"D. McIlroy,&nbsp;D. Pérez-Pinedo,&nbsp;S. Rosse-Guillevic,&nbsp;H. Muirhead-Hunt,&nbsp;R.S. Taylor,&nbsp;S.C. Dufour","doi":"10.1016/j.precamres.2025.107947","DOIUrl":"10.1016/j.precamres.2025.107947","url":null,"abstract":"<div><div>The Ediacaran of Newfoundland continues to yield a diverse biota of complex macro-organisms that records the early evolution of the Eumetazoa. The exceptional preservation of Rangeomorpha from the Fermeuse Formation at the Inner Meadow fossil site in Conception Bay, Newfoundland has allowed the recognition of a novel form of the genus <em>Charnia</em> with falcate first order branches that we describe as <em>Charnia brasieri</em> sp. nov. herein. Three dimensional reconstructions using pre-established conceptual models have predicted a central lumen to all first order branches, which is supported by the new Inner Meadow material. The inferred frond architecture of <em>C. brasieri</em> is sculpted in three dimensions herein and studied using computational fluid dynamics, which gives insights in the flow in and around the fossil organisms thereby informing its possible mode of life as procumbent epibenthic organism.</div><div>The falcate branching that characterizes <em>Charnia brasieri</em> sp. nov. is also seen in material previously described as <em>C. grandis</em> from the UK and Newfoundland. In reviewing the original diagnosis and figured material, we find <em>C. grandis</em> to be a distinct and valid taxon, reject its recent synonymization with <em>C. masoni</em>, and recognize its occurrence in the Ediacaran of Newfoundland. The large <em>Charnia</em> with falcate branching from Newfoundland and the UK are herein attributed to <em>C. brasieri,</em> with large size not being considered a valid taxobase. This work strongly suggests that <em>Charnia</em> is a long-lived, highly stable and morphologically-diverse genus characterized by rotated and furled rangeomorph branches, as conceptualized by Martin Brasier. The taphonomic and preservational insights from this work allow recognition of the lumina of <em>Charnia</em> and will require reconsideration of the palaeobiology of other members of the family Charniidae.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"431 ","pages":"Article 107947"},"PeriodicalIF":3.2,"publicationDate":"2025-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145419352","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":"Evidence for proximal ejecta from the 2.02 Ga Vredefort impact event","authors":"Matthew S. Huber ,&nbsp;Elizaveta Kovaleva ,&nbsp;Jonathan Hainsworth ,&nbsp;Masibulele Zintwana ,&nbsp;Dina Schultze ,&nbsp;Floyd Mautle ,&nbsp;Richard Wirth ,&nbsp;Christian Koeberl","doi":"10.1016/j.precamres.2025.107954","DOIUrl":"10.1016/j.precamres.2025.107954","url":null,"abstract":"<div><div>The Vredefort impact structure in South Africa is among the largest and oldest impact structures currently known on Earth. Due to extensive erosion, the proximal ejecta has been thought to have been removed completely. However, we find that sediments of the Doornfontein Member of the Gamagara Formation in the Griqualand West Basin resemble impact ejecta. They are located ca. 500 km west of the center of the Vredefort structure, which is within the modelled distance for the proximal ejecta, and are chronostratigraphically constrained to be between 1928 ± 4 Ma and 2222 ± 13 Ma, overlapping with the Vredefort event age (2019 ± 2 Ma). The stratigraphy of the Doornfontein Member includes an up to 100 m thick polymict breccia sequence that includes fragments of banded iron formation, chert, and carbonates, capped by accretionary lapilli. Shock metamorphic evidence in the form of quartz grains with planar deformation features and planar fractures, as well as granular zircons, are entrained within the breccia, confirming an impact origin. Primary compositions are obscured due to hematite alteration. We suggest that the economically significant Doornfontein Member represent proximal ejecta generated by the Vredefort event. Our discovery could represent the oldest described crater-ejecta pair and shows the potential for the preservation of massive Paleoproterozoic ejecta layers.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"431 ","pages":"Article 107954"},"PeriodicalIF":3.2,"publicationDate":"2025-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145419354","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":"Cryptic foreland basin strata of the southeastern Trans-Hudson Orogen revealed by detrital zircon geochronology","authors":"Jared P. Butler ,&nbsp;Alana M. Hinchey ,&nbsp;James L. Crowley","doi":"10.1016/j.precamres.2025.107961","DOIUrl":"10.1016/j.precamres.2025.107961","url":null,"abstract":"<div><div>Paleoproterozoic sedimentary sequences in the New Québec Orogen (NQO), northeastern Canada, record a complete Wilson cycle related to opening of the Manikewan Ocean and later Trans-Hudson orogeny. However, pinpointing the transition from extensional tectonics to foreland basin deposition has proved challenging owing to the composite character of the basin and a paucity of age constraints. We present results from a detrital zircon geochronological study of sedimentary rocks from cycles 1 to 3 of the Kaniapiskau Supergroup, in the foreland of the NQO, designed to assesses sediment provenance, determine maximum depositional ages (MDAs), and evaluate tectonic models. Cycle 1 sandstones yielded predominantly Neoarchean zircon and MDAs as young as 2365 ± 24 Ma, consistent with deposition during well-documented ca. 2.17 Ga rifting. Samples from Cycle 2, previously dated at ca. 1.88 Ga and variously ascribed to renewed rifting or development of a foreland basin, reveal a composite sequence comprising elements of both tectonic settings. Data from the Wishart Formation, the base of Cycle 2, are consistent with previously determined ca. 1.88 Ga ages for associated extensional magmatism, supporting deposition during a second phase of rifting. The stratigraphically higher Menihek Formation, meanwhile, yielded abundant Orosirian (ca. 2050–1800 Ma) zircon and MDAs as young as 1836.88 ± 1.08 Ma, indicating a pronounced hiatus and change in provenance. The unconformably overlying Tamarack River Formation (Cycle 3), widely interpreted as synorogenic molasse, produced bimodal age spectra with Orosirian and Neoarchean populations, and MDAs of 1815.00 ± 0.90 Ma. Late Orosirian zircon in the Menihek and Tamarack River formations was likely sourced from a ca. 1840–1810 Ma magmatic arc to the east of the NQO, suggesting that these units represent a foreland basin developed during Trans-Hudson orogenesis. Turbidite deposition in the underfilled foreland basin began &lt; ca. 1836 Ma following collision between the distal Superior craton and the Core Zone. Later, ca. 1815 Ma fluvial deposition of the Tamarack River Formation above deformed and eroded Menihek Formation probably reflects westward migration of the orogenic wedge and overfilling of the basin. The cryptic transition between precursor and foreland basin strata in the NQO highlights the importance of detrital zircon studies for investigating ancient basins with complex tectonic histories.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"431 ","pages":"Article 107961"},"PeriodicalIF":3.2,"publicationDate":"2025-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145419356","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":"Petrogenesis and chronology of albitite in the Yangtze Block, SW China: Tectonic implications for the Columbia supercontinent assembly","authors":"Luyu Huang ,&nbsp;Youliang Chen ,&nbsp;Jing Zhao ,&nbsp;Jian Yao ,&nbsp;Longlong Wei ,&nbsp;Yifan Zhu","doi":"10.1016/j.precamres.2025.107955","DOIUrl":"10.1016/j.precamres.2025.107955","url":null,"abstract":"<div><div>The Columbia supercontinent is recognized as the earliest demonstrably reconstructable supercontinent in the entire history of Earth. The Yangtze Block is an integral component of the Columbia supercontinent. However, an essential issue, which tectonic regime (convergent versus extensional) the block belonged to during middle Proterozoic remains controversial. Recently, the albitites were discovered in the Bajiaojing area of the western Yangtze Block, providing crucial insights into the evolution of the Paleoproterozoic crust of the Yangtze Block and its role in supercontinent dynamics. The magmatic zircons from the Bajiaojing albitites yielded U-Pb ages of 1858 ± 13 Ma and 1857 ± 10 Ma, and mineral chemical proxies (e.g., Yb/Sm, Nb/Ta, Y, U, Nb, and Ta) demonstrate that the Bajiaojing albitites originated from a granitoid source. Negative <em>ε</em>_Hf(<em>t</em>) values (−18.3–-4.4) and elemental ratios of whole-rock (e.g., Gd/Yb, Ta/Yb, and Nb/Ta) further indicate that the Bajiaojing albitite was likely emplaced in a collisional orogenic setting, in response to the late stage of collision. Combined with published zircon <em>ε</em>_Hf(<em>t</em>) values of Paleoproterozoic magmatic rocks across the Yangtze Block, we propose three distinct magmatic pulses at 2.02 Ga, 1.86 Ga, and 1.71 Ga, corresponding to early collision, late collision, and rift magmatism, respectively. From 2.02 Ga to 1.83 Ga, magmatic zircons in the Yangtze Block exhibit a persistent decline in <em>ε</em>_Hf(<em>t</em>) values, which reflects the continuous thickening of the block during this time.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"431 ","pages":"Article 107955"},"PeriodicalIF":3.2,"publicationDate":"2025-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145419355","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":"Petrogenesis of the Paleoproterozoic Wulong Gabbros: Insights into the post-collisional evolution of the southern North China Craton","authors":"Jian-Feng Ma ,&nbsp;Hamed Gamaleldien ,&nbsp;Yan-Yan Zhou ,&nbsp;Tai-Ping Zhao","doi":"10.1016/j.precamres.2025.107945","DOIUrl":"10.1016/j.precamres.2025.107945","url":null,"abstract":"<div><div>The North China Craton (NCC) has preserved nearly 3.8 billion years (Ga) of Earth’s evolutionary history. Although the formation and amalgamation mechanism of the NCC remains debated, it is widely accepted that its final collisional assembly was completed at ∼1.85 Ga, followed by over a billion years of stability. However, the timing of the post-collisional extension is not well constrained, leaving uncertainties in the mantle and crustal evolution processes after the craton’s formation. Here, we present new detailed geochronological, petrological, and geochemical data of Paleoproterozoic Wulong gabbros to investigate their origin and tectonic implications for the evolution of the NCC. Zircon and titanite U–Pb isotopic dating indicate that the Wulong gabbros formed at 1830 ± 19 Ma. The Wulong gabbros have low SiO₂ (49.4–52 wt%) and variable contents of MgO (3.9–7.2 wt%) with sub-chondritic Nd isotope compositions (εNd_(t) from −7.34 to −3.26), suggesting it was derived from the enriched mantle source. Reverse crystallization calculations indicate that the primary melts exhibit low SiO₂ (∼48.1 wt%) and high MgO (∼16.3 wt%) contents, along with moderate mantle potential temperatures (∼1361 °C) and pressures (∼1.83 GPa or ∼60 km). The new results suggested that the source magmas formed through 3–5 % partial melting of a spinel-bearing lithospheric mantle previously metasomatized by 0.5–10 % subduction-related fluids. The generated parental basaltic melt underwent fractional crystallization and minor plagioclase accumulation at approximately 1 GPa. Our new findings highlight that the Wulong gabbros were sourced from the extensional lithospheric mantle but stored in the thickened crust, marking the onset of post-collision extension in the North China Craton. Our work also highlights the asynchronous nature of mantle and crustal extension during the post-collisional stage and provide important insights into the Wilson cycle.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"431 ","pages":"Article 107945"},"PeriodicalIF":3.2,"publicationDate":"2025-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145365662","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":"Petrogenesis and U-Pb zircon age of the Anorthosite-Gabbronorite association near Barabar Hill, Chotanagpur Granite Gneiss Complex (CGGC), eastern Indian shield","authors":"Priyanka Negi ,&nbsp;Ashima Saikia ,&nbsp;Ivan Belousov ,&nbsp;Leonid V. Danyushevsky ,&nbsp;Mansoor Ahmad ,&nbsp;Salim Akhtar","doi":"10.1016/j.precamres.2025.107940","DOIUrl":"10.1016/j.precamres.2025.107940","url":null,"abstract":"<div><div>Massif-type anorthosite intrusions represent critical archives of Proterozoic mantle-crust interactions, crustal accretion and reworking processes. These voluminous, plagioclase-dominated cumulates were emplaced predominantly during the Statherian-Tonian period (1.8–0.9 Ga), and temporally associated with the assembly of Columbia and Rodinia supercontinents. Despite their widespread occurrences during the restricted time interval, the petrogenesis of massif-type anorthosite remains contentious. Competing models invoke derivation from upwelling mantle melts, partial melting of lower crust and/or magmatism within subduction-related arc settings. Their enigmatic origin and temporal confinement highlight their significance in deciphering Proterozoic tectono-magmatic evolution. The Barabar Hill anorthosite-gabbronorite association, located in the northern Chotanagpur Granite Gneissic Complex (CGGC) of Bihar (India), represents a previously undocumented Paleoproterozoic anorthosite magmatism that sheds new light on the genesis of anorthosites and the overall crustal evolution of the eastern Indian Shield. This study integrates field observations, petrography, bulk-rock major and trace element geochemistry, mineral chemistry, and U–Pb zircon geochronology to constrain the (1) source, (2) parental melt composition, (3) role of crustal contamination, if any, and (4) emplacement age of the Barabar Hill anorthosite − gabbronorite association. Thermobarometric calculations suggest that clinopyroxenes in the gabbronorites crystallized at 1100–1175 °C and 0.04–2.30 kbar, and zircons in the anorthosites crystallized at 600–765 °C under FMQ buffer conditions. Equilibrium Distribution Method (EDM) constrain parental melt compositions at TMF = 0–20 % for the anorthosites and 15–30 % for the gabbronorites. Assimilation–Fractional Crystallization (AFC) modelling suggests derivation of the anorthosites from a depleted mantle source with significant contributions from upper crustal materials.</div><div>U-Pb zircon geochronology constrains the emplacement age of the Barabar Hill suite to 1760.8 ± 7.3 to 1762.0 ± 3.8 Ma (Statherian period), thus representing the first record of Paleoproterozoic anorthosite magmatism in the eastern Indian Shield. The Barabar Hill anorthosite represents a globally significant example of subduction-related magmatism, distinct from Archean megacrystic and Proterozoic massif-type anorthosites. The findings of this study suggests that anorthosites massifs were formed from basaltic magmas derived from the depleted mantle which was contaminated by upper crustal granitic materials. A hybrid mantle-crust origin for anorthosites expand our current understanding of Proterozoic crustal evolution.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"431 ","pages":"Article 107940"},"PeriodicalIF":3.2,"publicationDate":"2025-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145327143","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":"Petrogenesis of the Paleoproterozoic Liuying hornblendite arc cumulates and implications for the tectonic evolution of the northern North China Craton","authors":"Wen-Mei Liu ,&nbsp;Jian-Ping Zheng ,&nbsp;Bernard Charlier ,&nbsp;Qiang Ma ,&nbsp;Timothy Kusky ,&nbsp;Hong-Kun Dai","doi":"10.1016/j.precamres.2025.107946","DOIUrl":"10.1016/j.precamres.2025.107946","url":null,"abstract":"<div><div>Understanding the Paleoproterozoic configuration of the northern North China Craton (NCC) is crucial for reconstructing its Precambrian tectonic history. This study integrates geological field observations, petrological data, U-Pb geochronology, and Lu-Hf isotopic analysis of zircons, alongside mineral and whole-rock geochemistry, including Sr-Nd isotopes from the Liuying ultramafic complex in Hebei Province. Our goal is to enhance the understanding of the tectonic history of the craton’s northern margin. The complex is composed of hornblendite and plagioclase hornblendite, showing igneous cumulate texture. Zircon U-Pb data from the ultramafic complex define three distinct groups of ages: 2211–2343 Ma, 1761–1999 Ma, and 246–310 Ma, corresponding to magma crystallization and metamorphism resulted from crustal thermal events. The major elements of rocks align with the differentiation trend of hydrous arc magmas. They display characteristics of enrichment in large ion lithophile elements and depletion in high field strength elements. Fractional crystallization of arc magmas with H₂O of 7.3–8.1 wt% at middle-lower crust depths (18–23 km) and 966–996 °C formed amphibole-enrichment arc cumulates. The zircon ε_Hf(t) values (–5.96 to + 9.05) are decoupled from enriched Sr-Nd isotopic compositions ((⁸⁷Sr/⁸⁶Sr)_i = 0.704185–0.705932, ε_Nd(t) = −14.6 to −5.68, (⁸⁷Sr/⁸⁶Sr)_amp = 0.705110–0.705846), suggesting a subduction-modified mantle source, incorporating 5–10 % subduction slab-derived melts and fluids. The northern part of the NCC was a continental arc above a paleo-subduction zone on a scale similar to the modern Andes at ca. 2.2 Ga. The oceanic slab subduction between the craton and the Siberian segment resulted in partial melting of metasomatized mantle wedge to form Paleoproterozoic hornblendite arc cumulates.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"431 ","pages":"Article 107946"},"PeriodicalIF":3.2,"publicationDate":"2025-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145327142","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":"Pre-Mesoproterozoic crustal framework and Mesoproterozoic evolution of the SW Angolan Shield: structural, geochemical, and isotopic insights from the Kunene Complex and surrounding basement","authors":"Enrique Merino-Martínez ,&nbsp;Ezequiel Ferreira ,&nbsp;Pablo Valverde-Vaquero ,&nbsp;José Feliciano Rodrigues ,&nbsp;Javier Escuder-Viruete ,&nbsp;José Luis García-Lobón ,&nbsp;Aratz Beranoaguirre ,&nbsp;María del Carmen Feria ,&nbsp;Carmen Rey-Moral ,&nbsp;Paulo Bravo Silva ,&nbsp;Pablo González-Cuadra ,&nbsp;João Carlos Sousa ,&nbsp;Julián Potti ,&nbsp;Jaime Máximo ,&nbsp;Miguel Gutiérrez-Medina ,&nbsp;Juan Carlos Gumiel ,&nbsp;Gustavo Galán ,&nbsp;Tania Mochales ,&nbsp;José Manuel ,&nbsp;Domingos Cordeiro ,&nbsp;Carmen Galindo","doi":"10.1016/j.precamres.2025.107937","DOIUrl":"10.1016/j.precamres.2025.107937","url":null,"abstract":"<div><div>The southwestern Angolan Shield hosts the Earth’s largest Mesoproterozoic massif-type anorthosite complex (up to 53,500 km²), the Kunene Complex (KC). This complex is the result of a long-lived (∼200 Ma) episodic emplacement of coalescent magmatic pulses. The recent acquisition of multidisciplinary data during the PLANAGEO project has significantly enhanced our understanding of the Precambrian crustal framework from the southwestern Angolan Shield. Combined multi-isotope, structural and geophysical data reveals distinctive crustal zones in the southwestern Angolan Shield that clearly influenced KC’s emplacement within a back-arc setting. The spatio-temporal arrangement of KC pulses suggests westwards magma migration within a complex contractional regime involving large strike-slip systems. A long-lasting and extensive accretionary orogen was responsible for the tectono-thermal activity recorded during most of the Mesoproterozoic. Crustal thinning and partial melting of isotopically heterogeneous lower-crustal sources through mantle upwelling promoted the episodic felsic magmatism contemporaneous with the KC. Crustal contamination processes are evident in gabbro-anorthosites, indicating mantle metasomatism and interaction with wall-rocks and granite melts during ascent, upwelled by lateral-driven forces. Deposition of extensive metasedimentary sequences (&lt;1.26 Ga) covering the KC, along with 1.23–1.07 Ga sublithospheric and mantle-derived magmatism, indicate a shift from a compressional to an extensional regime during late-Mesoproterozoic times. Regional correlations with other Mesoproterozoic units in African and Brazilian counterparts suggest a shared geological evolution, despite potential differences in tectonic setting. These findings supports a refined geological model for the Mesoproterozoic evolution of the southwestern part of the Congo Craton.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"431 ","pages":"Article 107937"},"PeriodicalIF":3.2,"publicationDate":"2025-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145327169","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}