Precambrian Research最新文献

{"title":"Neoproterozoic tectonothermal overprint on the Southern São Francisco Craton basement, Brazil","authors":"Everton Marques Bongiolo ,&nbsp;Christophe Renac ,&nbsp;Ciro Alexandre Ávila ,&nbsp;Sylvain Gallet ,&nbsp;Reiner Neumann","doi":"10.1016/j.precamres.2024.107537","DOIUrl":"10.1016/j.precamres.2024.107537","url":null,"abstract":"<div><p>The Archean domain of the Southern São Francisco Craton (SFC) acted as a foreland for the docking of the Mineiro Belt (2.47–2.05 Ga) through soft-collision processes during the Paleoproterozoic. Much later, during the Neoproterozoic, the newly formed Archean-Paleoproterozoic protocraton again served as a foreland for the development of thrust belts that contributed to the formation of the Gondwana supercontinent. From the Paleoproterozoic to the Neoproterozoic, pressure–temperature (P-T) conditions in the SFC crust varied from prograde amphibolite to retrograde amphibolite-greenschist metamorphic facies. In this paper, we reinterpret past ⁴⁰K/⁴⁰Ar data and present new ⁴⁰Ar/³⁹Ar dates in biotite and amphibole—evaluating the P-T conditions affecting metagranitoids, orthogneisses, and metamafic rocks of the southern SFC basement—to reconstruct its tectonothermal history during the assembly of the Gondwana supercontinent. Recalculated ⁴⁰K/⁴⁰Ar* and new ’total fusion’ ⁴⁰Ar/³⁹Ar dates facilitated the creation of a contour map with a 900 Ma isochron, roughly corresponding to the tectonic boundary between the Archean and Paleoproterozoic domains, with the Neoproterozoic tectonothermal imprint recorded south of the 900 Ma line. The younger ⁴⁰Ar/³⁹Ar plateau dates from 651 to 526 Ma obtained on biotite crystals delineate a 600 Ma isochron within the Mineiro Belt area, approximately coinciding with the Lenheiro Shear Zone (LSZ). This comprehensive dataset, encompassing dates from 900 to 526 Ma, underscores a polycyclic tectonothermal reactivation that either delimits the Mineiro Belt area or occurs along the LSZ. This prominent structure within the belt differentiates deeper plutonic rocks from shallower (sub)volcanic rocks to its north and south regions, respectively. These relatively deeper to shallower crustal positions suggest that Neoproterozoic collisional fronts developed progressively from northwest (earlier collisions) to southeast (later collisions), corresponding to older and younger dates, respectively. Additionally, Discordia lower-intercepts in Wetherill diagrams from 977 to 488 Ma, obtained in previous U-Pb investigations within the Mineiro Belt, align with our new ⁴⁰Ar/³⁹Ar plateau and ’total fusion’ dates, providing further evidence for reheating and partial to complete resetting of magmatic biotite-amphibole crystals and neoformed metamorphic biotite. Our results confirm that the Mineiro Belt did not behave as a stable continental landmass during the Neoproterozoic Brasiliano Orogeny, instead experiencing significant tectonothermal overprinting.</p></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141940955","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 comments on “New evidence for the Baltican cratonic affinity and Tonian to Ediacaran tectonic evolution of West Avalonia in the Avalon Peninsula, Newfoundland, Canada” of Beranek et al. (2023)","authors":"Luke P. Beranek ,&nbsp;Alexander D. Hutter ,&nbsp;Stephen Pearcey ,&nbsp;Corey James ,&nbsp;Vanessa Langor ,&nbsp;Calum Pike ,&nbsp;Dylan Goudie ,&nbsp;Lindsay Oldham","doi":"10.1016/j.precamres.2024.107534","DOIUrl":"10.1016/j.precamres.2024.107534","url":null,"abstract":"","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141940957","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":"Snapshot of a Paleoarchean seafloor: Evidence from 3.43-3.35 Ga Strelley Pool chert-pebble conglomerate for deposition, silicification, and erosion of hydrothermal greenalite-apatite precipitates","authors":"B. Rasmussen ,&nbsp;J.R. Muhling ,&nbsp;A. Sadekov","doi":"10.1016/j.precamres.2024.107531","DOIUrl":"10.1016/j.precamres.2024.107531","url":null,"abstract":"<div><p>Some of the oldest, well-preserved exhalative sedimentary rocks (ferruginous cherts and jaspilites) occur in volcanic-dominated Paleoarchean sequences in the northern Pilbara Craton, Australia. Jaspilites contain fine-grained hematite particles that have been interpreted to have formed following seawater oxidation of vent-derived Fe²⁺(aq) by photoautotrophs. However, recent studies suggest that most of the iron in the jaspilites was originally deposited as Fe(II)-rich silicates such as greenalite, sparking renewed debate about how iron was precipitated in the early oceans. Here we show that rounded clasts of dusty ferruginous chert in basal conglomerates of the 3.43–3.35 Ga Strelley Pool Formation, North Pole Dome, Pilbara Craton, Australia, contain abundant nanoparticles of greenalite and apatite that are texturally, mineralogically and chemically near-identical to occurrences in Neoarchean banded iron formations in the Hamersley Group, Australia. Hematite where present occurs in trace amounts and its distribution along the edges of clasts implies that at least some of the hematite formed during weathering. The greenalite-rich clasts display a pronounced positive shale-normalized Eu anomaly, small positive Y anomaly and lack a positive La anomaly, features typical of Paleoarchean exhalites. The co-occurrence of greenalite- and apatite-rich chert-pebbles with clasts of hydrothermal black chert and silicified felsic volcaniclastic sedimentary rocks points to a volcanically active provenance with vigorous hydrothermal activity, consistent with derivation from the underlying 3.43 Ga Panorama Formation. We argue that the greenalite and apatite nanoparticles precipitated during mixing between hydrothermal vent fluids and anoxic seawater and were silicified on the seafloor. The round to oval shape of the chert clasts indicates that the silica cement had recrystallized prior to erosion, consistent with the presence of polygonal shrinkage structures in the dusty chert clasts. Our findings imply that greenalite, contrary to recent suggestions, not only formed in Paleoarchean seawater, but was also stable during deposition, diagenesis, and resedimentation. The precipitation and non-dissolution of apatite nanoparticles in Paleoarchean seawater points to elevated phosphate concentrations, whereas the absence of primary hematite is consistent with models advocating a role for abiotic iron deposition during the Archean.</p></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0301926824002444/pdfft?md5=f8e9d7cfa3169d35153290e273d2d929&pid=1-s2.0-S0301926824002444-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141883674","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evidence for, and significance of, the Neoproterozoic Xuefeng Orogeny, South China","authors":"Jia Liu ,&nbsp;Yajun Xu ,&nbsp;Peter A. Cawood ,&nbsp;Yu Liu ,&nbsp;Haowen Xiao ,&nbsp;Gaoquan Liu ,&nbsp;Jiahui Zhang","doi":"10.1016/j.precamres.2024.107532","DOIUrl":"10.1016/j.precamres.2024.107532","url":null,"abstract":"<div><p>The recognition of unconformities is important for determining the long-term evolution of orogenic belts. We document an unconformity between Tonian and Cryogenian strata of the Nanhua Basin of South China. This stratigraphic break has previously been termed the Xuefeng Movement and is developed within the Yangtze Block and western Cathaysia Block. Deformation characteristics and detrital zircon U-Pb geochronology from rock units underlying and overlying the unconformity (i.e., the Niuguping and Gucheng formations, respectively) from the Anhua region of the northern Hunan Province in the southeastern Yangtze Block are documented. The Niuguping Formation displays a set of top-to-northwest imbricate thrust faults and related fault-propagation folds, NEE-plunging subparallel crenulation lineations, a foliation, and shows widespread greenschist facies metamorphism. In contrast, the overlying Gucheng Formation exhibits no obvious stratal deformation (apart from a mild inclination of bedding) and is unmetamorphosed. Detrital zircon age spectra of the samples from the Niuguping Formation are characterized by unimodal age peaks of ca. 750–730 Ma, while those of the samples from the Gucheng Formation yield a multimodal age distribution, with a few <em>syn</em>-sedimentary detrital zircons (&lt;700 Ma), and much older zircons with age peaks of ca. 800 Ma, 2.1–1.9 Ga, and 2.6–2.3 Ga. Combining this data with previous geochronology indicates deposition of the Niuguping and Gucheng formations in the late Tonian (725–720 Ma) and Cryogenian (690–660 Ma), respectively. The time gap across the unconformity is some 30 Ma (720–690 Ma). The unconformity and associated structural and metamorphic break extend across the Yangtze Block and western Cathaysia Block, defining a major regional orogenic event. The significantly different detrital zircon spectra of strata across the unconformity suggest a dramatic change in the source due to the Xuefeng Orogeny in the Yangtze Block. Zircon U-Pb-Hf isotopic evidence indicates that detritus of the Niuguping Formation below the unconformity was derived from <em>syn</em>-depositional magmatic activity in the northern Yangtze Block, while a significant increase of Archean to Paleoproterozoic ages for the Gucheng Formation, suggests that the Xuefeng Orogeny resulted in crustal thickening and denudation in the northern Yangtze Block. These changes in provenance, along with changing deformational and metamorphic patterns, indicate evolution of the Nanhua Basin from a compressional to an extensional back-arc basin, which we infer is related to tectonic switching from an advancing to a retreating subduction system in the northern Yangtze Block at the time of the unconformity.</p></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141883475","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":"New perspectives on the tectonic evolution of the eastern Paraguay Belt revealed through zircon U-Pb-Hf-O systematics of the inner units","authors":"Gabriella Labate Frugis ,&nbsp;Mario da Costa Campos Neto ,&nbsp;Alice Westin ,&nbsp;Christopher Mark Fanning","doi":"10.1016/j.precamres.2024.107529","DOIUrl":"10.1016/j.precamres.2024.107529","url":null,"abstract":"<div><p>The Paraguay Belt and Brasília Orogen, the western and eastern segments of the Tocantins Province, respectively, recorded the interactions among the Amazonian, São Francisco-Congo Craton, and Paranapanema Block during the amalgamation of Western Gondwana. The Paraguay Belt joins the Brasília Orogen in the Transbrasiliano Lineament, which separates metasedimentary rocks to the west from metavolcano-sedimentary rocks to the east. This study focuses on four geological units cropping out in Brazil, between the Mato Grosso State southeastern region and the Goiás State western region: the Nova Xavantina Metavolcano-sedimentary Sequence (NXS), the Cuiabá Group (CG), the Barra do Garças-Coxim Unit (BGCU), a newly identified register of foreland sedimentation, and the Bom Jardim de Goiás Metavolcano-sedimentary Sequence (BJGS). Whole-rock elemental geochemistry and Nd-Sr isotopes, along with zircon U-Pb-Hf-O systematics, provide insights into the evolution of this domain.</p><p>Metavolcanic rocks from the NXS suggest that it represents a back-arc extensional tectonic environment with oceanic spreading (zircon age of ca. 710 Ma with δ¹⁸O of 4.8 ‰ and chondritic εHf₍_t) formed along the southeastern edge of the Amazonian Craton. Metarenites preserve bimodal sources of ca. 0.85 Ga and ca. 1.90 Ga, while lithic metarenites exhibit Mesoproterozoic zircon grains suggesting sources from both the Amazonian Craton and the Paranapanema Block. The maximum depositional age of the lithic metarenites is ca. 715 Ma, coinciding with the age of the volcanic peak. The CG is interpreted as passive margin deposits through the erosion of depleted Mesoproterozoic (1.50–1.45 Ga and 1.23–1.17 Ga) and more evolved Paleoproterozoic (1.97–1.77 Ga) rocks from the Amazonian Craton.</p><p>Metasedimentary rocks from the BGCU present age peaks of 800–600 Ma, recording the input of juvenile material into the basin as revealed by zircon grains of ca. 716 Ma and ca. 810 Ma with δ¹⁸O of 4.7–4.8 ‰ and εHf_(t) of + 7. These findings indicate Goiás Magmatic Arc juvenile sources and disclose the evolution of the unit towards a continental arc, as suggested by more evolved zircon grains younger than ca. 700 Ma. Gneisses of ca. 690–655 Ma occur as basement rocks of the BGCU and suggest prolongation of the Goiás Magmatic Arc westward within the Transbrasiliano corridor.</p></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141883467","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 basal Cambrian carbon isotope excursion revealed in the Central Iberian Zone, Spain","authors":"Kun Zhang ,&nbsp;Graham A. Shields ,&nbsp;Ying Zhou ,&nbsp;Harald Strauss ,&nbsp;Ulrich Struck ,&nbsp;Sören Jensen","doi":"10.1016/j.precamres.2024.107526","DOIUrl":"10.1016/j.precamres.2024.107526","url":null,"abstract":"<div><p>The causes of early metazoan diversification during the Ediacaran-Cambrian transition interval are controversial, partly because the global correlation of the Ediacaran-Cambrian boundary remains problematic due to a lack of unambiguous stratigraphic markers. Here we report geochemical data from two fossiliferous sections (Majada de Andaluz and Vía Verde) that straddle the Ediacaran-Cambrian interval in the Central Iberian Zone, Spain. Carbon isotope chemostratigraphy reveals a rise to a low positive δ¹³C_carb plateau at the base of the Majada section, which is associated with the first appearance of <em>Cloudina</em> and a pristine Sr isotope value of 0.708512, suggesting that the lower Villarta Formation correlates with the terminal Ediacaran strata in China and Namibia. A prominent negative δ¹³C_carb excursion is also revealed from the lower member of the Villarta Formation at Majada, likely corresponding to the global basal Cambrian carbon isotope excursion (BACE). Nitrogen isotope data from the correlative Vía Verde section reveal a similar trend to that found in coeval strata of South China, and indicate a change from predominantly anaerobic to aerobic nitrogen cycling in Central Iberia. By correlating sections in which both the BACE excursion and <em>Treptichnus pedum</em> are recognized, it appears that <em>T. pedum</em> is exclusively found above the BACE, which postdates the last appearance of <em>Cloudina</em> and a negative δ¹³C_carb plateau. Further studies of sections with both fossil and isotopic control will help to constrain the timing and causation of Ediacaran-Cambrian bioradiations as well as their relationship to global carbon cycle perturbations.</p></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0301926824002390/pdfft?md5=079cf07a765fb805bc828c8e1e457e35&pid=1-s2.0-S0301926824002390-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141883468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Architecture and dynamics of Precambrian linear megadunes: Galho do Miguel Formation, Mesoproterozoic, South-East Brazil","authors":"Áquila Ferreira Mesquita ,&nbsp;Giorgio Basilici ,&nbsp;Alexandre Ribeiro Cardoso ,&nbsp;Carlos Roberto de Souza Filho ,&nbsp;Nigel P. Mountney ,&nbsp;Luca Colombera ,&nbsp;Grace I.E. Cosgrove ,&nbsp;Juraj Janočko ,&nbsp;Davi Machado Querubim","doi":"10.1016/j.precamres.2024.107533","DOIUrl":"10.1016/j.precamres.2024.107533","url":null,"abstract":"<div><p>Recognizing the deposits of linear megadunes in ancient aeolian successions is challenging when the original bedform topography is not preserved. The present study provides a detailed analysis of the depositional architecture of an ∼ 80 m-thick interval of the Mesoproterozoic Galho do Miguel Formation (SE Brazil) to reconstruct the original morphologies of linear megadunes and to understand their dynamics. The depositional architecture reveals compound cross-bedded sets, which transition laterally into thick low-angle cross-stratified sets and planar-parallel sandstone beds. The depositional features indicate the presence of complex megadunes separated by adjoining wide dry inter-megadune areas, which were themselves flooded seasonally by a water table that rose above the depositional surface. Linear megadunes experienced two phases of development: vertical accretion and subsequent episode of lateral migration. During the vertical accretion phase, high sediment supply, typical of Precambrian aeolian systems, and the convergence of winds from two distinct directions promoted high rates of megadune growth, bedform elongation, and the formation of superimposed dunes. The lateral migration phase was characterised by a component of lateral bedform shift relative to the main along-crest sediment transport direction; this prevented preservation of a bimodal pattern of dune cross-strata azimuths. The accumulation of these deposits occurred via a combination of megadune climbing that occurred with progressive rise of the water-table level. The water-table rise hindered cannibalization of the lower parts of the migrating megadunes, allowing the accumulation and subsequent preservation of megadune sandstone packages. The rise of the water table was also responsible for the accumulation of thick dry inter-megadune strata. The unusual thickness of linear megadune and inter-megadune deposits of the Galho do Miguel Formation, as compared with Phanerozoic examples, are attributed to the interplay between the barren conditions of the early Earth, the morphodynamics of the linear megadunes, and the seasonal impact of the water table at the accumulation surface. Without a water-table control, opportunities for megadune accumulation and preservation were likely limited in Precambrian ergs.</p></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141883669","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":"Early-stage intracontinental rifting in the Neoproterozoic Centralian Superbasin: Systematic U–Pb and Lu–Hf isotopes in detrital and inherited zircons from the Yeneena Basin, northwest Australia","authors":"Fariba Kohanpour ,&nbsp;Ian Tyler ,&nbsp;Weronika Gorczyk ,&nbsp;David Kelsey ,&nbsp;Chris Fisher ,&nbsp;Anthony Kemp","doi":"10.1016/j.precamres.2024.107524","DOIUrl":"10.1016/j.precamres.2024.107524","url":null,"abstract":"<div><p>Detrital zircons from different lithostratigraphic units of Supersequence 1 across the Neoproterozoic northwest Officer and Yeneena basins were investigated using LA-ICPMS U−Pb and Lu − Hf isotope analyses to understand the source of detritus and potential links to regional tectono-magmatic events, as well as the crustal evolution of the sedimentary sources terranes. All data show that Proterozoic detritus dominate the age spectra of samples from the Yeneena Basin and northwest Officer Basin, with signatures varying in the heights of peaks rather than the presence or absence of age groups in different formations. The Archean and Proterozoic ages overlap with known magmatic events in the Pilbara Craton, Fortescue Basin, Rudall Province, Capricorn Orogen, Musgrave Province, Madura Province, and the Coompana Province suggesting these terranes are possible sources of the detritus. The detrital zircon population of the samples have main age peaks in the range 1300 to 1000 Ma, suggesting magmatic rocks of the Rudall and Musgrave provinces are the main sources of detrital zircons, which can be differentiated by Hf signature. The distal Musgrave Province persistently dominates the provenance of detritus in the northwestern Officer and Yeneena basins, while detritus from the proximal Rudall Province contributes to a lesser extent. This suggests that the distal Musgrave Province remained emergent during the evolution of the northwestern Officer Basin and the Yeneena Basin, whereas the proximal Rudall Province potentially became buried by the accumulating sedimentary rocks and contributed less detrital zircons. The 833.6 ± 1.4 Ma maximum depositional age obtained in this study for the sedimentary rocks of the northwestern Officer and Yeneena basins point to the approximate time of the start of basins development. The extensional event in this age period is related to emplacement and extrusion of the ca. 830 Ma Willouran Large Igneous Province (LIP). The Duke gabbro sills observed in the Yeneena Basin are part of this LIP, which extends from the Adelaide Rift Complex, through the Musgrave Province, central–northwest Officer Basin and into the Yeneena Basin. The sediment source terranes suggest a southeast–northwest oriented depositional system between central and Western Australia, possibly because of intracontinental rifting related to widespread mafic–ultramafic magmatic events that could include the earlier Ngaanyatjarra Rift formed by the 1090–1040 Ma Warakurna LIP as well as the ca. 830 Ma Willouran LIP, synchronous with the breakup of Rodinia in the mid-Neoproterozoic.</p></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141883471","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 western Amazonian affinity in the periphery of the Nuna supercontinent for Mesoproterozoic basements in the southern Central Asian orogenic belt","authors":"Qian Liu ,&nbsp;Yigui Han ,&nbsp;Jinlong Yao ,&nbsp;Jianhua Li ,&nbsp;Peng Wang ,&nbsp;Donghai Zhang ,&nbsp;Guochun Zhao ,&nbsp;Toshiaki Tsunogae","doi":"10.1016/j.precamres.2024.107528","DOIUrl":"10.1016/j.precamres.2024.107528","url":null,"abstract":"<div><p>The Central Asian orogenic belt (CAOB) is one of the largest Phanerozoic accretionary orogens in Earth’s history with myriad metal deposits. Mesoproterozoic basements are sporadically preserved along the southern CAOB. Their tectonic affinity remains controversial, which hampers us from better understanding the basic architecture and Phanerozoic tectonic evolution of the CAOB. This study identified Mesoproterozoic sedimentary rocks in the northeastern Altyn Tagh, southeast of the Tarim craton, from which detrital zircons have remarkable U-Pb age peaks at ca. 1.7 and 1.4 Ga and highly variable <em>ε</em>_Hf(<em>t</em>) values from −9 to + 14, resembling those from the southern CAOB. Based on provenance tracing and comparison of available geological records, the Mesoproterozoic basements in the southern CAOB show an affinity with the Rondonian-San Ignacio Province in western Amazonia associated with the peripheral accretion of the Nuna supercontinent and were subsequently fragmented and dispersed over 3000 km in distance. Predominately juvenile 1.8–1.3 Ga magmatic rocks with a scarcity of ca. 1.4 Ga ones in southern Laurentia and southwestern Baltica preclude a possible link. Likewise, a paucity of ca. 1.4 Ga zircons and incomparable isotope signatures in North China, India, and Australia challenge their affinities with the CAOB’s basements. This work focuses on the tectonic attribution of the Mesoproterozoic basements in the southern CAOB and highlights the energetic Mesoproterozoic era, during which the accretionary orogeny was intensely operative along the periphery of the Nuna supercontinent.</p></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141883469","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":"Lithium isotopic compositions of the Neoarchean Huoqiu BIF and the Paleoproterozoic Yuanjiacun BIF from North China Craton: Implications for the triggering mechanism of the Great Oxidation Event","authors":"Erhao Shan ,&nbsp;Yilin Xiao ,&nbsp;Yang-Yang Wang ,&nbsp;Dongbo Tan ,&nbsp;He Sun","doi":"10.1016/j.precamres.2024.107527","DOIUrl":"10.1016/j.precamres.2024.107527","url":null,"abstract":"<div><p>It has been generally agreed that changes in Earth surface systems are the key factors to trigger the Great Oxidation Event (GOE) at about 2.4 Ga. In the present study, we selected banded iron formation (BIF) samples that formed at ∼2.54 Ga (before the onset of the GOE) and ∼2.28 Ga (after the onset of the GOE) from the North China Craton (NCC) for Li isotope investigations, which represent an effective tool for studying continental silicate weathering processes, to reveal possible changes in Earth’s surface systems before and after the onset of the GOE. Using the Li isotope fractionation coefficients between iron oxide and fluid first obtained by our synthetic experiments, we demonstrate that the Li isotopic composition (δ⁷Li values) of ancient seawater increased from ∼+10.5 ‰ at 2.54 Ga to ∼+15 ‰ at 2.28 Ga. Monte Carlo simulations based on mass balance show that changes in the riverine Li isotopic composition are the main reason for the variations in the δ⁷Li values of seawater during this period. In view of the present data, enhanced erosion rates caused by uplifted mountains and increased secondary mineral formation in floodplains are the main reasons for this riverine change. The close coupling of δ⁷Li values with the ⁸⁷Sr/⁸⁶Sr values of seawater, εHf values and δ¹⁸O values of zircon and preserved orogeny length over time indicate the assembly of supercratons before GOE initiation. The assembly of small and scattered landmasses could be the cause of mountain uplift, and thus enhanced erosion rates bring more nutrients to the ocean through collisional orogenic processes accompanied by these convergences, promoting aerobic photosynthesis, e.g., the participation of cyanobacteria, disrupting the balance between oxygen production and consumption, and finally triggering the GOE.</p></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141883470","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}