Precambrian Research最新文献

{"title":"Tonian intra-oceanic subduction initiation at the northwestern Yangtze Block: Evidence from forearc ophiolite fragments in the Bikou microblock","authors":"Li Qin ,&nbsp;Xianzhi Pei ,&nbsp;Ruibao Li ,&nbsp;Lei Pei ,&nbsp;Chengjun Liu ,&nbsp;Zuochen Li ,&nbsp;Shaowei Zhao ,&nbsp;Feng Gao","doi":"10.1016/j.precamres.2025.107997","DOIUrl":"10.1016/j.precamres.2025.107997","url":null,"abstract":"<div><div>The Bikou Group, situated in the southern part of the Bikou microblock along the northwestern Yangtze Block, preserves extensive remnants of Tonian volcanic magmatism. However, the timing of its formation and its tectonic setting remain debated. In this study, we report a newly identified geological record of subduction initiation from the Heimulin forearc ophiolite in the Bikou microblock. The Heimulin ophiolite comprises Tonian forearc peridotites, forearc basalts (diabases), boninites, high-Mg andesites and dacites, resembling the forearc igneous sequences observed in the Izu-Bonin-Mariana (IBM) subduction zone. Forearc basalts (diabase) with zircon U-Pb ages of 841 Ma exhibit geochemical signatures similar to normal mid-ocean ridge basalts (N-MORB) but lower Ti/V ratios indicate slightly higher concentrations of fluid-mobile elements than N-MORB. In contrast, the ∼ 834 Ma boninite displays more pronounced depletion in high field strength elements (HFSEs) and Heavy rare earth elements (HREEs) compared to the FABs. The high-Mg andesites (HMAs) and dacites yield zircon U-Pb ages of 833 Ma and 825 Ma, respectively. The HMAs were derived from partial melting of a mantle wedge metasomatized by melts/fluids released from a subducting oceanic slab, whereas the dacites were produced in a mature intra-oceanic arc setting through dehydration melting of mafic rocks in the middle to lower crust. The Heimulin forearc ophiolites record a magmatic evolution from less to more HFSE-depleted and LILE-enriched, similar to the magmatic evolution of the IBM forearc, reflecting progressive subduction of the oceanic slab. Inherited zircons and negative Hf isotopes indicate the presence of ribbon-like continental fragments in the Heimulin intra-oceanic arc, which may have facilitated the initiation of Tonian intra-oceanic subduction in the Heimulin Ocean. Integrated with previously published reliable data, our study provides further evidence that the northwestern Yangtze Block experienced continuous subduction-accretion processes during the Tonian, with the Yangtze Block (South China Block) likely situated on the margin of the Rodinia supercontinent.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"433 ","pages":"Article 107997"},"PeriodicalIF":3.2,"publicationDate":"2025-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145798579","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":"2025-12-16","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":"2025-12-12","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}

{"title":"Identification of eclogites that record Palaeoproterozoic and Triassic metamorphism in the Dabie UHP orogenic belt, eastern-central China","authors":"Jianhui Liu ,&nbsp;Wei Jin ,&nbsp;Fulai Liu ,&nbsp;Zhengjiang Ding ,&nbsp;Yuanshuo Li ,&nbsp;Weinan Xu","doi":"10.1016/j.precamres.2025.107990","DOIUrl":"10.1016/j.precamres.2025.107990","url":null,"abstract":"<div><div>In this study, zircon U–Th–Pb dating coupled with zircon morphology and texture observations, and trace element and Hf isotope analyses conducted on ultrahigh-pressure (UHP) eclogites and the host granitic gneiss in the central Dabie UHP belt has identified Neoarchean (ca. 2.5 Ga), Palaeoproterozoic (ca. 1.9 Ga) metamorphic events and Triassic UHP metamorphism at ca. 236 Ma. The Palaeoproterozoic metamorphic zircons from two eclogite samples and one granitic gneiss sample have consistent weighted mean ages of 1871 ± 26, 1890 ± 15, and 1915 ± 41 Ma, respectively. They exhibit low Th/U ratios (mostly &lt; 0.1), depletions in light rare earth elements (LREE) and enrichments in heavy rare earth elements (HREE) characterized by steep chondrite-normalized patterns, and yielded a large range of Ti-in-zircon temperatures varying from 892 ℃ to 642 ℃, indicating their metamorphic recrystallization or growth under wide metamorphic condition. The Palaeoproterozoic metamorphic zircons from the eclogites have mostly uniform Hf compositions and positive ε_Hf(t) values distinctly different from the Palaeoproterozoic metamorphic zircons with variable Hf compositions and negative ε_Hf(t) values from the host granitic gneiss. The Triassic metamorphic zircons from two eclogite samples and one granitic gneiss sample gave weighted-mean ages of 236 ± 2, 236 ± 1 and 234 ± 3 Ma, respectively. They exhibit low Th/U ratios (mostly &lt; 0.1), depletions in LREE and distinctively flat chondrite-normalized HREE patterns, and mostly consistent Hf isotope compositions with extremely low ¹⁷⁶Lu/¹⁷⁷Hf ratios and negative ε_Hf(t) values, and yielded Ti-in-zircon temperature of ca. 724℃ consistent with Triassic UHP metamorphic temperature, thus, these zircons is interpreted to be formed under Triassic UHP metamorphism. The host granitic gneiss has a minimum estimate of magmatic crystallization age of 2723 Ma. Therefore, it can be concluded that mafic protolith of the eclogite and the host granitic gneiss together experienced Palaeoproterozoic metamorphism at ca. 1.9 Ga and then Triassic UHP metamorphism at ca. 236 Ma. Additionally, it has further been suggested that the Early Precambrian basement exists and was involved in Triassic UHP metamorphism in the central Dabie UHP belt.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"433 ","pages":"Article 107990"},"PeriodicalIF":3.2,"publicationDate":"2025-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145749410","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":"2025-12-08","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":"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":"2025-12-06","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":"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":"2025-12-06","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":"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":"2025-12-05","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":"Constraining crustal-level granite emplacement through thermobarometry and gravity modelling: Insights from the Ediacaran Acari Batholith, Borborema Province, NE Brazil","authors":"Christian C.B. Rocha ,&nbsp;Rafael G. Motta ,&nbsp;Nitzschia R.R. Domingos ,&nbsp;Frederico C.J. Vilalva ,&nbsp;Rogério Cavalcante ,&nbsp;Dinarte Lucas","doi":"10.1016/j.precamres.2025.107977","DOIUrl":"10.1016/j.precamres.2025.107977","url":null,"abstract":"<div><div>The Acari Batholith is a syntectonic Ediacaran (∼575 Ma) intrusion emplaced in the Seridó Belt, northeastern Brazil, during the Brasiliano Orogeny, a major tectonic event associated with the assembly of West Gondwana. It represents the largest granitic body within the belt. While the exposed geology of the Acari Batholith is well characterized, its subsurface geometry remains poorly constrained. To address this, we performed 2.5D forward gravity modelling to investigate its architecture and integrated the results with existing AMS, thermobarometric, borehole, and regional data. The modelling results represent one plausible subsurface configuration that is consistent with the gravity data and available geological constraints. They reveal an eastward-shifted feeder zone with two NE-SW aligned roots. The model suggests a predominantly shallow body, with a low-angle floor. A thin mica schist layer overlies the northern root and separates the Acari Batholith from the Acauã Stock, a satellite body that belongs to the same magmatic system. Thermobarometric estimates based on the normative quartz–orthoclase–albite geobarometer yield crystallization pressures of 2.6–3.5 kbar, consistent with the HT/LP metamorphism in the Seridó Belt. Synchronicity between magma emplacement and Brasiliano deformation is inferred from the alignment of internal magmatic fabrics with regional structures, while a mylonitic zone along its western margin developed after solidification. Cordierite + sillimanite assemblages in adjacent mica schist further attest to high temperatures near the roots. Combined with regional data, these results support the interpretation that the Acari Batholith represents a magmatic expression of the migmatitic dome system formed during Brasiliano transpression.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"432 ","pages":"Article 107977"},"PeriodicalIF":3.2,"publicationDate":"2025-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145618078","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":"Petrochronology and genesis of granite-hosted rare metal (Ta, Nb, Li, Y + REE, Zr)-F-bearing mineral occurrences in the Cameroon Northern Domain of the Central African Orogenic Belt","authors":"Thierry Bineli Betsi ,&nbsp;Eric Joseph Njee ,&nbsp;Louise Marie Ngo Bidjeck Bondje ,&nbsp;Eugene Pascal Binam Mandeng ,&nbsp;Kirsten Drüppel ,&nbsp;Aratz Beranoaguirre ,&nbsp;Hubert Mvondo ,&nbsp;Tebogo Kelepile ,&nbsp;Elisabeth Eiche ,&nbsp;Jochen Kolb ,&nbsp;Charles Nkoumbou","doi":"10.1016/j.precamres.2025.107966","DOIUrl":"10.1016/j.precamres.2025.107966","url":null,"abstract":"<div><div>The Ngoutchoumi Granite Complex in the Cameroonian Northern Domain (ND) of the Neoproterozoic Central African Orogenic Belt has long been known to host tungsten mineral occurrences. Here, we show that this granite complex also contains a suite of rare metals (Ta, Nb, Zr, Li, Y + REE) and F-bearing minerals, which have not been previously reported. The key genetic aspects pertaining to the genesis of this mineralised system are unconstrained. In this study, that couples <em>in-situ</em> LA-ICP-MS zircon and columbite U-Pb and mica<!--> ⁴⁰Ar-³⁹Ar geochronology with bulk-rock and mineral geochemistry and Raman spectroscopy, the rare metal minerals and their host granite are characterized. The granite is peraluminous and rich in REE (100–445 ppm), with strong LREE enrichment ((La/Yb)_N<!-->= 2.38–41.4) and typically displays a pronounced negative Eu anomaly (Eu/Eu* = 0.06–0.10). Rare metal minerals, including ferrocolumbite, Nb-rich rutile, zircon and various REE minerals are intimately associated with fluorite. Zircon and ferrocolumbite from the rare metal-rich granite yield Pan-African ages of 639 ± 11 Ma and 640.2 ± 12.7 Ma, respectively, indicating part of the rare metal minerals is orthomagmatic. Textural and mineral chemistry features indicate that the primary orthomagmatic rare metal minerals were overprinted, thus leading to at least three episodes of rare metal mineralisation. On the other hand, biotite and muscovite from granite crosscutting the rare metal granite yield Ar-Ar plateau ages of 549.02 ± 0.85 and 552.17 ± 0.22 Ma, respectively, which, when combined with our ferrocolumbite age, as well as previously reported rare metal-related ages within the ND, bracket the age of rare metal mineralisation events within the ND, between ca.640–580 Ma. Our findings, therefore, extend both the spatial and temporal fingerprints of the ND rare metal mineralisation beyond those previously reported and have significant implications for the exploration of rare metals in Pan-African terranes. The episodes of formation of rare metals at Ngoutchoumi span from the orthomagmatic stage to the hydrothermal stage, and this genetic model sheds new light on the genesis of rare metal granite-type deposits, where debates have revolved around metasomatic vs. magmatic rare metal enrichment processes.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"432 ","pages":"Article 107966"},"PeriodicalIF":3.2,"publicationDate":"2025-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145579883","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}