Precambrian Research最新文献

{"title":"Subduction-induced crustal growth in the Neoproterozoic continental magmatic arc: Evidence from arc-type high-Mg# diorites and adakitic granitoids in the western Yangtze Block, South China","authors":"Rui-Yang Liu ,&nbsp;Shao-cong Lai ,&nbsp;Yu Zhu ,&nbsp;Ren-Zhi Zhu ,&nbsp;Min Liu ,&nbsp;Jiang-Feng Qin ,&nbsp;Fang-yi Zhang ,&nbsp;Hang Yang","doi":"10.1016/j.precamres.2025.107892","DOIUrl":"10.1016/j.precamres.2025.107892","url":null,"abstract":"<div><div>The coexistence of normal arc-type mafic-intermediate rocks and adakitic granodiorites can provide significant insights into the subduction-induced crustal growth. In this study, we present the comprehensive study of petrology, mineralogy, zircon U-Pb geochronology, bulk rock major and trace elements, Sr-Nd isotopes, zircon Lu-Hf isotopes, and electron microprobe (plagioclase, amphibole, biotite, and clinopyroxene) for the newly identified Neoproterozoic high-Mg^# diorites (HMA) and adakitic granodiorites from the Kangding area along the western margin of the Yangtze Block (South China), to explore the subduction-induced crustal growth in the Neoproterozoic continental arc magma. The results show that the high-Mg^# diorites formed at 792.9 Ma, and have much andesines, labradorites, high magnesium biotites and iron hornblendes, and are characterized by variably high MgO (3.62 ∼ 5.82 wt%) contents and Mg^# (58.36 ∼ 60.49) values, showing the positive bulk rock ε_Nd(t) (+0.84 ∼ +2.19) and zircon εHf(t) (+4.18 ∼ +9.44) values. The adakitic granodiorites formed at 793.5 Ma, and have much mineral of quartz, plagioclase, biotite as well as minor pyroxene and iron calcium magnesium amphibole. They contain high Sr (463.14 ∼ 494.44 ppm) and Y (10.41 ∼ 13.81 ppm) contents as well as Sr/Y (35.69 ∼ 47.49) ratios, indicating the adakitic dffinity. Theses adakitic granodiorites display positive ε_Nd(t) (+1.52 ∼ +1.83) and zircon ε_Hf(t) (+3.45 ∼ +7.14) values. Both types of rocks are enriched in LREEs (Light rare earth elements) and LILEs (Large ion lithophile elements) and depleted in Nb, Ta and Ti. We suggest that these high-Mg^# diorites were derived from the partial melting of metasomatized mantle source enriched by subduction-related fluids, and the adakitic granodiorites were formed by partial melting of thickened juvenile mafic lower crust, which can reveal the subduction-induced crustal growth.</div><div>Combined with 860 ∼780 Ma mafic-intermediate-felsic rocks and 800 ∼750 Ma adakitic granitoids, we support that the Neoproterozoicc crustal growth were induced by metasomatized mantle-derived magmas. The subduction-induced crustal growth is vital for moulding the geochemical characteristics of arc magmatic rock types.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"428 ","pages":"Article 107892"},"PeriodicalIF":3.2,"publicationDate":"2025-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144841253","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 identification of a ca. 2165–2163 Ma large igneous province on the Kaapvaal Craton in southern Africa with implications for chronostratigraphy, paleogeography and environmental change in the early Paleoproterozoic","authors":"Ashley Gumsley ,&nbsp;Kevin Chamberlain ,&nbsp;Anna Gumsley ,&nbsp;Michiel de Kock ,&nbsp;Beata Marciniak-Maliszewska ,&nbsp;Dominika Niezabitowska ,&nbsp;Ulf Söderlund ,&nbsp;Agnieszka Bylina ,&nbsp;Artur Szlęzak","doi":"10.1016/j.precamres.2025.107889","DOIUrl":"10.1016/j.precamres.2025.107889","url":null,"abstract":"<div><div>Large igneous provinces (LIPs) are excellent spatial and temporal geological recorders. However, our understanding of LIPs is hindered by a lack of preservation and alteration of many LIPs through deep time. Several LIPs have been emplaced in the Rhyacian. These LIPs demonstrate a connection across the Superior, Wyoming and North Atlantic cratons. In this study we use new U-Pb ID-TIMS baddeleyite geochronology, petrography, geochemistry, paleomagnetic and rock magnetic data on mafic intrusions to show that the Kaapvaal Craton in southern Africa was possibly a part of this ‘clan of cratons’. New ages come from the Buffalo River Gorge Dyke Swarm on the south-easternmost region of the craton, dated herein at 2165 ± 6 Ma and 2163 ± 3 Ma. A younger 2148 ± 3 Ma dyke was also identified in the region. These dykes invite comparison to magmatic units within the upper Transvaal Supergroup, including the Hekpoort Formation basaltic andesites and the Machadodorp Member basalts, together with the Mashishing Dyke Swarm and various sills, with at least the Hekpoort recognised as a LIP in the ca. 2.22–2.14 Ga time frame. However, this new magmatic event is close in age to a reported ca. 2.16–2.14 Ga metamorphic event within the Transvaal Supergroup. In addition, a new Rhyacian magmatic barcode record for the Kaapvaal Craton is presented that can be compared with coeval LIPs in the Superior, Wyoming and North Atlantic cratons. We suggest that the Kaapvaal Craton was likely a near neighbour to these cratonic blocks at ca. 2.16–2.15 Ga when combining the new magmatic barcode record with a new tentative virtual geomagnetic pole at -57.4°N, 9.1°E (dp/dm of 20.2/22.9).</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"428 ","pages":"Article 107889"},"PeriodicalIF":3.2,"publicationDate":"2025-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144841369","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":"U–Pb geochronology of the Malokaroy Series (Kazakhstan) constrains the global appearance of vase-shaped microfossils to > 759 million years ago","authors":"Mary C. Lonsdale ,&nbsp;Lyle L. Nelson ,&nbsp;Dawid Szymanowski ,&nbsp;Sezim Mustapayeva ,&nbsp;Uyanga Bold ,&nbsp;Blair Schoene ,&nbsp;Emily F. Smith","doi":"10.1016/j.precamres.2025.107888","DOIUrl":"10.1016/j.precamres.2025.107888","url":null,"abstract":"<div><div>The appearance of vase-shaped microfossils (VSMs) in the sedimentary record evidences the acquisition of tests by eukaryotes in the late Tonian Period. However, the timing of this biological innovation is uncertain, in part because of a paucity of high-precision radiometric age constraints on VSM-bearing sedimentary successions outside of Laurentia. Here, we investigate the chronostratigraphy of one such succession, the Malokaroy Series in Kazakhstan. The Malokaroy Series was recently interpreted to record deposition in a c. 810–730 Ma continental forearc basin. It includes the Aktugai, Chichkan and Kurgan formations, the middle of which preserves a fossil assemblage with vase-shaped microfossils (VSMs). Outside of Kazakhstan, the appearance of the oldest known VSM taxon is constrained to between 789–752 Ma. The age of the Chichkan assemblage has been variably interpreted, but was recently suggested to be &lt; 737 Ma.</div><div>Here, we produce a U–Pb CA-ID-TIMS magmatic zircon age of 759.4 ± 2.5 Ma from an ash collected near the top of the Kurgan Formation. It demonstrates that the top of the Malokaroy Series is ∼ 30 Myr older than most recently suggested and that the Chichkan VSMs are &gt; 759 Ma. We also present zircon trace element ratios from the dated ash consistent with crystallization in an intra-plate setting. Given these data, as well as sedimentological observations, we suggest that the Malokaroy Series records a distinct tectonostratigraphic event, and definitively extend Tonian VSMs to &gt; 759 Ma.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"427 ","pages":"Article 107888"},"PeriodicalIF":3.2,"publicationDate":"2025-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144810414","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":"2.4–2.3 Ga granitoids of the Arrowsmith orogeny, southwestern Rae craton, Canada: Syn- and post-orogenic magmatism during a global tectono-magmatic lull","authors":"Benjamin J.C. Neil ,&nbsp;Thomas Chacko ,&nbsp;Larry M. Heaman ,&nbsp;S. Andy Dufrane ,&nbsp;Robert A. Creaser ,&nbsp;Edith Martel ,&nbsp;Rebecca Canam ,&nbsp;D. Graham Pearson","doi":"10.1016/j.precamres.2025.107880","DOIUrl":"10.1016/j.precamres.2025.107880","url":null,"abstract":"<div><div>Constraints on the tectonic and magmatic processes that occurred during the 2.4–2.2 Ga tectono-magmatic lull are limited by the relative paucity of 2.4–2.2 Ga magmatic rocks available for study. One place with a substantial record of 2.4–2.3 Ga magmatism is the western Rae craton. We present whole-rock geochemical and Nd isotope data, and zircon U-Pb-Hf isotope and trace-element data for granitoids in an understudied portion of the southwestern Rae craton. Two groups of granitoids are documented, ca. 2.43–2.38 Ga leucogranitoids and ca. 2.32–2.31 Ga biotite granites. All of the granitoids are peraluminous and silica rich (&gt;69 wt% SiO₂), and have negative initial εNd and εHf values. The ca. 2.43–2.38 Ga leucogranitoids have comparatively low high-field strength element contents, zircon saturation temperatures (677–828 °C) and Ti-in-zircon temperatures (medians = 707–798 °C), and some of them contain abundant inherited zircon. Their generation was in part coeval with ca. 2.38 Ga migmatization of local metasedimentary and mafic metaigneous rocks. The ca. 2.32–2.31 Ga granites have elevated high-field strength and light rare earth element contents, relatively high zircon saturation (785–905 °C) and Ti-in-zircon (medians = 724–899 °C) temperatures, strongly negative initial εNd (−5 to −11) and εHf (−10 to −18) values, and little-to-no inherited zircon. These granites were produced via high-temperature (&gt;900 °C) melting of tonalitic-granodioritic rocks, including a significant proportion &gt; 3.0 Ga rocks that must be widespread at depth in the study area. Evidence of ca. 2.35–2.30 Ga mafic magmatism that could have supplied heat for this high-temperature melting has not been identified in the study area, but has been documented elsewhere in the western Rae craton. We propose that the ca. 2.43–2.38 Ga leucogranitoids reflect anatexis in response to one or more episodes of collisional orogenesis and the ca. 2.32–2.31 Ga granites formed in a post-orogenic setting. Comparisons with ca. 1.85–1.75 Ga syn- and post-orogenic granitoids associated with the Trans-Hudson orogen support these tectonic interpretations and indicate that the 2.4–2.3 Ga granitoids were produced through “modern-style” tectonic processes, similar to those that occurred during the Trans-Hudson orogeny.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"427 ","pages":"Article 107880"},"PeriodicalIF":3.2,"publicationDate":"2025-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144771542","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":"Coevolution of life and environment during the Ediacaran-Cambrian transition: Clues from litho-, bio-, and chemostratigraphy of the Corumbá Group, Brazil","authors":"Henrique Albuquerque Fernandes ,&nbsp;Gustavo Paula Santos ,&nbsp;Luiz Gustavo Pereira ,&nbsp;Leonardo Thomaz Rimi ,&nbsp;Thales Pescarini ,&nbsp;Eric Elias ,&nbsp;Carolina Bedoya Rueda ,&nbsp;Vinícius Cardoso Lucas ,&nbsp;Larissa Rodrigues ,&nbsp;Karina Mazzamuto ,&nbsp;Ligia Stama ,&nbsp;Sergio Caetano Filho ,&nbsp;Marly Babinski ,&nbsp;Paulo César Boggiani ,&nbsp;Juliana de Moraes Leme ,&nbsp;Fred Bowyer ,&nbsp;Catherine V. Rose ,&nbsp;Ricardo Ivan Ferreira Trindade","doi":"10.1016/j.precamres.2025.107887","DOIUrl":"10.1016/j.precamres.2025.107887","url":null,"abstract":"<div><div>This study presents new litho-, bio-, and chemostratigraphic data of the late Ediacaran Corumbá Group (Brazil) obtained from two drill cores that were collected as part of the GRIND-ECT project (Geological Research through Integrated Neoproterozoic Drilling – Ediacaran-Cambrian Transition). This is the first study encompassing, continuously, the Bocaina (ca. 570–555 Ma) and Tamengo (ca. 550–540 Ma) formations, which are key carbonate units from the upper Corumbá Group and optimal archives for investigating the ECT in Western Gondwana. Sequence stratigraphic analysis reveals two third-order transgressive–regressive cycles. A sequence boundary at the Bocaina-Tamengo Limit (BTL) formed during a major, potentially glacio-eustatic, regression, after which the morphology of the carbonate platform changed from a rimmed/open shelf to a distally-steepened ramp. Biostratigraphic analysis constrains the lowest regional occurrence of <em>Cloudina</em> shortly above the BTL. Four species of acritarchs from the genus <em>Leiosphaeridea</em> and <em>Germinosphaera</em> are documented in the Tamengo Formation, revealing an association with the Late Ediacaran Leiosphere Palynoflora. <em>Cloudina</em> and <em>Leiosphaeridea</em> show biostratigraphic trends linked to third-order cycles, being more abundant during shallower intervals. The δ¹³C_carb curve in the Bocaina Formation exhibits a relatively stable trend around +2 ‰, followed by a minor negative excursion (<em>n1</em>) down to −1.7 ‰ at the BTL, which is also present in other sections on the Corumbá platform. Above <em>n1</em>, the Tamengo Formation exhibits a positive excursion reaching values of +6 ‰. Confidence in precise correlation between the global carbon isotope curve and the Corumbá Group curve is somewhat hampered, given the uncertain age of the lowermost Bocaina Formation. It is possible that <em>n1</em> is temporally equivalent to the globally documented negative excursion at 550 Ma, suggesting that these excursions, in part, result from diagenetic alteration or local effects that were exacerbated during a major glacio-eustatic regression. Despite having values consistent with the Late Ediacaran Positive carbon Isotope Plateau, the Tamengo Formation lacks negative excursions that may exist in the global curve, such as A0, which may cast doubt on the global nature of this event. The links between sequence-, bio-, and chemostratigraphy presented herein indicate an intricate coevolution of life and environment during the ECT.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"427 ","pages":"Article 107887"},"PeriodicalIF":3.2,"publicationDate":"2025-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144757499","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 Ediacaran vendotaenid fossils from North Gondwana margin (Anti-Atlas, Morocco): Spatiotemporal distribution and stratigraphic significance","authors":"Kai Chen ,&nbsp;Aihua Yang ,&nbsp;El Hafid Bouougri ,&nbsp;Fangchen Zhao ,&nbsp;Chunlin Hu ,&nbsp;Bing Pan ,&nbsp;Chuan Yang ,&nbsp;Bo Chen ,&nbsp;Tianchen He ,&nbsp;Xiaojuan Sun ,&nbsp;Yiwei Xiong ,&nbsp;Maoyan Zhu","doi":"10.1016/j.precamres.2025.107882","DOIUrl":"10.1016/j.precamres.2025.107882","url":null,"abstract":"<div><div><em>Vendotaenia</em>, a simple ribbon-like fossil, is classified within the informal vendotaenid group alongside morphologically similar fossils. These fossils, which are frequently encountered near the Precambrian-Cambrian boundary, have been hypothesized to possess potential for stratigraphic correlation. However, their taxonomy is often ambiguous and the occurrences in older strata challenge their biostratigraphic significance. In this study, we first report vendotaenid fossils from the Late Ediacaran Tabia Member of the Adoudou Formation in Morocco. Based on meticulous morphological examination of the abundant specimens, these fossils are identified into three distinct morphological taxa, including <em>Vendotaenia</em>, characterized by a constant width and smooth curvature; <em>Tyrasotaenia</em>, also of constant width but commonly folded and twisted; and the lanceolate form <em>Lanceoforma</em>. Furthermore, we have reassessed the related fossil reports within a comprehensive database to evaluate their spatiotemporal distribution. The result shows that all three fossil genera exhibit long temporal ranges with the first appearances predating the Ediacaran. Given their simplistic and often indistinguishable morphology, <em>Vendotaenia</em> and related vendotaenids are deemed unsuitable for stratigraphic correlation of the uppermost Ediacaran.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"427 ","pages":"Article 107882"},"PeriodicalIF":3.2,"publicationDate":"2025-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144703599","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 Adoudou Biota: A new window on the Ediacaran-Cambrian transition from the western Anti-Atlas, Morocco","authors":"Abdelfattah Azizi ,&nbsp;Olev Vinn ,&nbsp;Asmaa El Bakhouch ,&nbsp;Kalle Kirsimäe ,&nbsp;Ahmid Hafid ,&nbsp;Khadija El Hariri","doi":"10.1016/j.precamres.2025.107885","DOIUrl":"10.1016/j.precamres.2025.107885","url":null,"abstract":"<div><div>The Ediacaran-Cambrian transition represents one of the most pivotal periods in the history of life, characterized by the decline of the Ediacaran ecosystems and fauna, and the emergence of Phanerozoic-type fauna. Various interpretations have been proposed for this biological event, including the closing of the unique Ediacaran taphonomic window, a sudden extinction event, or an evolutionary “biotic replacement” event. Here, we describe a fossil locality from the western Anti-Atlas of Morocco that preserves metazoan trace fossils and soft-bodied Ediacara biota, mat-related structures (MRS), alongside a paleoenvironmental reconstruction of the siliciclastic deposits of the Tabia Member of the Adoudou Formation. We document various MRS, including mat-related wrinkles and mat destruction features reported from frequently shallow submerged environments and down to permanently sub-wavebase settings. Additionally, we report new trace fossils from this interval, including <em>T. bifurcus</em>, <em>Bergaueria</em>, <em>Helminthopsis</em>, and <em>Archaeonassa</em> preserved on the bedding plane of sandstone beds. Furthermore, we describe new Ediacaran body fossils comprising macroscopic, well-preserved specimens of <em>Aspidella</em> and <em>Nimbia</em>. An integrated study of sedimentary facies and the distribution of associated trace fossils indicates that evolutionary innovations exerted primary control on the distribution of trace fossils in the studied interval, where the stratigraphical distribution of trace fossils strongly aligns with that observed worldwide. The stratigraphic overlap of soft-bodied Ediacara biota and metazoan trace fossils suggests the existence of unique late Ediacaran shallow-water ecosystems housing two distinct multicellular clades.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"427 ","pages":"Article 107885"},"PeriodicalIF":3.2,"publicationDate":"2025-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144703601","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":"Reply to comment on “Debunking the myth of a single Iron Ore Group in the Singhbhum Craton, India”","authors":"Jaganmoy Jodder ,&nbsp;Axel Hofmann ,&nbsp;Marlina A. Elburg ,&nbsp;Rebeun Ngobeli ,&nbsp;Trond H. Torsvik","doi":"10.1016/j.precamres.2025.107884","DOIUrl":"10.1016/j.precamres.2025.107884","url":null,"abstract":"","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"427 ","pages":"Article 107884"},"PeriodicalIF":3.2,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144696435","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":"Geochemistry, U-Pb geochronology, and Sm-Nd isotopes of the granitic rocks associated with the Rosa de Maio gold deposit in the Tapajós Mineral Province, Brazil: Magmatic evolution, source characterization, and implications for magma fertility","authors":"Pedro Victor F. de S. Alves ,&nbsp;Nilson F. Botelho ,&nbsp;Valmir da S. Souza ,&nbsp;Lys M. Cunha ,&nbsp;Guilherme Gonçalves ,&nbsp;José Antonio H. Coaquira ,&nbsp;Federico A.J. Cuadros ,&nbsp;Elder Yokoyama","doi":"10.1016/j.precamres.2025.107883","DOIUrl":"10.1016/j.precamres.2025.107883","url":null,"abstract":"<div><div>Porphyry Cu-Au deposits form a continuous spectrum from Cu-rich to Au-rich types. Although they share many common features, Au-rich porphyry deposits are more closely associated with high-K calc-alkaline to alkaline intrusions emplaced at shallow depths in thin continental crust, with associated magmatic rocks displaying lower Sr/Y and La/Yb ratios. The magmatic and hydrothermal factors controlling Cu/Au endowments remain debated and include timing of magmatic sulfide saturation and remobilization of metals during the hydrothermal stage. The Tapajós Mineral Province (TMP) hosts multiple Au(–Cu-Mo) deposits in the southern-central Amazonian Craton (northern Brazil), some recognized as part of porphyry-epithermal systems, associated with either the arc magmatism of the older magmatic sequence (2.0–1.95 Ga) or the post-collisional to early-anorogenic magmatism of the younger magmatic sequence (1.90–1.86 Ga), which includes the Parauari Suite (PAR, 1.89–1.87 Ga). The Rosa de Maio, Bandeirantes, and Maués are magmatic-hydrothermal Au deposits associated with the PAR, with features comparable to those of Au-rich porphyry systems, and whose magmatic evolution and Au fertility remain poorly constrained. In this study, we investigate the fertile magmatism and present new lithogeochemistry, mineral chemistry, Mössbauer spectroscopy on biotite, zircon and monazite U-Pb dating, and Sm-Nd isotope data of the host rocks. Fractional crystallization played a major role in their magmatic evolution, differentiating from tonalitic/granodioritic parental magmas to biotite monzo-/syenogranitic and muscovite syeno-/alkali feldspar granitic magmas. Ferric/ferrous iron ratios estimated by Mössbauer spectroscopy on magmatic biotite indicate oxygen fugacity conditions above the NNO buffer. The Bandeirantes intrusion and the Rosa de Maio Granite (RMG) were emplaced at <em>ca.</em> 1907 Ma and 1890 Ma, respectively, in a late- to post-collisional setting, following a period of subduction-controlled arc magmatism. Neodymium isotope data reveal that the sources of the RMG involve contributions from both juvenile material and crustal rocks from the basement. The RMG shares some similarities with Au-rich porphyry-style deposits, including low Cu/Au ratios, low Sr/Y and La/Yb values of associated magmatic rocks, and relatively oxidized high-K calc-alkaline magmatism in a post-collisional setting. Magmatic sulfide saturation, a potential factor controlling low Cu/Au ratios, may have been a first-order control on the Au fertility of the RMG.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"427 ","pages":"Article 107883"},"PeriodicalIF":3.2,"publicationDate":"2025-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144678794","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":"Lithostratigraphic, structural and geochronological framework of the Namibe region, SW Angola: Insights into the late Eburnean Orogeny in the Congo Shield","authors":"Javier Escuder-Viruete ,&nbsp;Luis Quintana ,&nbsp;Aratz Beranoaguirre ,&nbsp;Pilar Montero ,&nbsp;Janet Gabites ,&nbsp;Pablo Valverde-Vaquero ,&nbsp;Américo da Mata Lourenço Victorino","doi":"10.1016/j.precamres.2025.107879","DOIUrl":"10.1016/j.precamres.2025.107879","url":null,"abstract":"<div><div>The Namibe region in southwestern Angola represents the southernmost extent of the Southwestern Congo Shield; however, its tectonothermal evolution is still poorly understood. To better constrain the timing and deformation style of the outcropping rocks in this region, we integrated (i) 1:250,000-scale lithostratigraphic and structural geological mapping, (ii) SHRIMP U–Pb zircon dating of metamorphic rocks, and (iii) ⁴⁰Ar/³⁹Ar muscovite cooling ages. The study area comprises the Epupa Complex of ortho- and paragneisses, overlain by the Namibe Group, which is composed of supracrustal metasediments. The sharp lithological contrast, absence of orthogneisses, and the preservation of basal marbles suggest that the protoliths of the Namibe Group were unconformably deposited on the Epupa Complex. Both units experienced polyphase ductile deformation during the Eburnean event. Two penetrative deformation phases (D1 and D2) are overprinted by two later, less pervasive phases (D3 and D4). A subhorizontal D₂ shear zone links sinistral transpression in the upper crust with lateral flow in a partially molten lower crust. Peak metamorphic conditions led to widespread anatexis. SHRIMP U–Pb zircon ages from migmatitic leucosomes, granitic–tonalitic orthogneisses, and detrital to metamorphic zircons cluster tightly between 1.82 and 1.80 Ga, while ⁴⁰Ar/³⁹Ar muscovite ages indicate cooling at ∼1.80 Ga. This implies that the thermal peak, melt segregation, granite emplacement, and cooling occurred within ≤10 Ma. The near-synchronicity of high-grade metamorphism and magmatism, together with the crustal-scale D₂ shear architecture, supports a model of hot, thickened crust undergoing vertical strain transfer during late Eburnean sinistral transpression. This study provides the first precise 1.82–1.80 Ga age bracket for the late Eburnean event in southwestern Angola, highlighting a well-preserved subhorizontal attachment zone that couples upper crustal shear with deep crustal flow.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"427 ","pages":"Article 107879"},"PeriodicalIF":3.2,"publicationDate":"2025-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144632741","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}