Precambrian Research最新文献

{"title":"The influence of mafic and felsic crust on the seawater chemistry ca. 3.0 billion years ago: Evidence from Nd isotopes in banded iron formations from the Murchison Greenstone Belt","authors":"J. Krayer ,&nbsp;J. Jodder ,&nbsp;A. Hofmann ,&nbsp;S. Weyer ,&nbsp;M. Willbold ,&nbsp;T. Schulz ,&nbsp;C. Koeberl ,&nbsp;S. Viehmann","doi":"10.1016/j.precamres.2025.107701","DOIUrl":"10.1016/j.precamres.2025.107701","url":null,"abstract":"<div><div>Banded iron formations (BIFs) are marine chemical sedimentary rocks that serve as prime archives for Precambrian paleo-environmental reconstructions. However, due to the scarcity of well-preserved Archean rocks, the aquatic environments of early Earth remain poorly constrained. In particular, fluxes derived from continents and submarine hydrothermal systems that affected Archean seawater chemistry are crucial for the understanding of the evolution of marine environments.</div><div>To fill this gap, we present major- and trace element data in combination with Sm-Nd isotopes of individual BIF layers from the ca. 3.0 Ga old Murchison Greenstone Belt (MGB) of South Africa. BIF layers with low immobile element concentrations show seawater-like shale-normalized (subscript SN) rare earth and yttrium (REY_SN) patterns with heavy over light REY_SN enrichment and positive La_SN, Eu_SN, Gd_SN, and Y_SN anomalies, implying an anoxic marine depositional setting with contributions from high-temperature, hydrothermal systems. These BIF samples yield a Sm-Nd age of 2993 ± 97 Ma that overlaps with the proposed depositional age suggesting negligible post-depositional alteration. In contrast, BIF layers with non-seawater-like REY_SN patterns yield a Sm-Nd age of 2504 ± 161 Ma, which can be linked to post-depositional alteration during the ca. 2.7 Ga Limpopo orogeny. The range of initial εNd values from −1.74 to + 0.15 in pristine BIF samples suggests that elements of mixed juvenile and evolved material from emerged continents and/or hydrothermal systems affected Murchison seawater and indicates potential oceanic water mixing in the Murchison region with water masses derived from the northern Pietersburg and the southern Kaapvaal regions.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"418 ","pages":"Article 107701"},"PeriodicalIF":3.2,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143182947","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":"Crustal evolution and architecture of the Wawa Subprovince, Superior Province: Insights from zircon U-Pb-Hf-O isotopes and geochemistry","authors":"K.G. Nymoen ,&nbsp;D.R. Mole ,&nbsp;P.C. Thurston ,&nbsp;D.K. Tinkham ,&nbsp;J.H. Marsh ,&nbsp;R.A. Stern","doi":"10.1016/j.precamres.2025.107705","DOIUrl":"10.1016/j.precamres.2025.107705","url":null,"abstract":"<div><div>The tectono-magmatic processes driving the evolution of Archean continental crust in the early-Earth are highly debated topics. To contribute to a better understanding of crustal evolution in the Meso- to Neoarchean, the Wawa subprovince of the Superior Province, comprising ∼ 2.9–2.6 Ga crustal rocks, represents an ideal location, located along-strike of the well-studied and mineralised Abitibi Subprovince. Here, we integrate whole-rock geochemistry and in-situ zircon U-Pb geochronology, Hf-O isotopes and trace element data from new and compiled magmatic samples across, and proximal to, the Wawa subprovince. Geochronology is used to identify four major volcano-magmatic stages at 2900–2750 Ma (I), 2750–2710 Ma (II), 2710–2680 Ma (III) and 2680–2670 Ma (IV), generally correlating with previous studies from the Michipicoten greenstone belt within the Wawa subprovince. Zircon Hf-isotopic data indicate TTG and felsic volcanic rocks follow two distinct crustal evolution lines from ∼ 3.2 Ga (mafic crust) and ∼ 2.9 Ga (felsic crust). We suggest at least two different sources are responsible for generating crust in the southwestern part of the SE Superior Province in the Archean; the older source is less juvenile and relatively dry, and the younger source is more juvenile and hydrous. Integration of isotopic data with whole-rock Sr/Y, La/Yb_N and Nb, indicates that the depth of magma generation from Source 1 is shallower than that from Source 2, indicating an increase in crustal thickness from Stage I through Stage IV. The comparable Hf-isotopic signatures of the Wawa subprovince, Eastern Wabigoon subprovince and Winnipeg River Terrane samples suggest these areas may have a long-lived, shared crustal evolution.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"418 ","pages":"Article 107705"},"PeriodicalIF":3.2,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143182946","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":"Tokko section as a deeply eroded part of the Mesoarchean Tokko-Khani greenstone belt, the west Aldan shield, Siberian craton","authors":"Kseniya G. Erofeeva ,&nbsp;Alexander V. Samsonov ,&nbsp;Yulia O. Larionova ,&nbsp;Daniil A. Rylov ,&nbsp;Olga E. Plusnina ,&nbsp;Anfisa V. Skoblenko ,&nbsp;Alexander S. Dubenskiy","doi":"10.1016/j.precamres.2025.107696","DOIUrl":"10.1016/j.precamres.2025.107696","url":null,"abstract":"<div><div>This paper presents new data on the Tokko section of the central part of the Olekma granite-greenstone terrain (Aldan Shield, Siberian craton). The conducted studies provide grounds to propose that the Tokko section exposes a fragment of a deeply eroded greenstone belt, similar on the evolution to the Olondo greenstone belt. In that light the Tokko section may have been merged with the Olondo fragment within a single structure of the Tokko-Khani greenstone belt.</div><div>Juvenile geochemical signatures of felsic magmatism in the Tokko segment support the idea of the existence of an oceanic basin in the central part of the Olekma granite-greenstone terrain, evolution of which could give rise to the formation of the subduction systems and generation of the new crust during the Mesoarchean. It has been established that the main volume of the Archean crust in the Tokko section was formed between 3.0 and 2.8 Ga, primarily contributed by juvenile granitoids, and subordinately by mafic magmatism. The following stage of the crust formation is recorded by bimodal magmatism at ca. 2.6 Ga, accompanied by the ascent of mafic asthenospheric magmas and intrusion of crustal granitoids. The rocks of this association, together with the contemporaneous granites from the eastern part of the Olekma granite-greenstone terrain, and anorthosites with granitoids of the Kalar, Altual’skii, and Dzheluiskii Complexes distributed within the junction zone of the Olekma granite-greenstone terrain and the Dzhugdzhur-Stanovoi fold region, may represent a part of the single Neoarchean anorthosite-mangerite-charnockite-granite magmatic province.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"418 ","pages":"Article 107696"},"PeriodicalIF":3.2,"publicationDate":"2025-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143182499","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":"Age constraints on the Ediacaran carbonate carbon isotope excursions in the Tarim Block: Evidence from in situ U–Pb dating of dolostone","authors":"Wen-Wu Huang ,&nbsp;Liang-Liang Zhang ,&nbsp;Di-Cheng Zhu ,&nbsp;Li Liu ,&nbsp;Xiao-Wei Li ,&nbsp;Jin-Cheng Xie ,&nbsp;Qing Wang ,&nbsp;Hao-Yin Chi","doi":"10.1016/j.precamres.2025.107691","DOIUrl":"10.1016/j.precamres.2025.107691","url":null,"abstract":"<div><div>The Ediacaran period is characterized by a significant negative carbon isotope excursion (N3) of carbonate, followed by a subsequent positive excursion (P1). The timing of the N3 and P1 excursions, particularly the latter, is poorly constrained due to the lack of suitable dating techniques. In this study, we use the newly developed <em>in situ</em> carbonate U–Pb dating technique on Ediacaran carbonates from the Qigebrak Formation at two sections in the Tarim Block, northwestern China, to constrain the timing of P1 for intra- and interbasinal correlation. We also test the applicability of carbonate U–Pb dating coupled with elemental geochemistry to Precambrian carbonates, where post-depositional recrystallization or hydrothermal alteration frequently occurs. Our results indicate that the Tarim carbonate carbon isotope positive excursion (TP1) starts at ∼560 Ma and ends at ∼550 Ma. A compilation of age data from worldwide Ediacaran sections suggests that N3 lasted from ∼570 Ma to ∼560 Ma, and P1 from ∼560 Ma to ∼550 Ma. Finally, we summarized the differences in sedimentary petrology and geochemical characteristics between well-preserved and recrystallized/altered Precambrian carbonates to provide useful criteria for the future geological applicability of U–Pb dating results of Precambrian carbonates. These criteria include: 1. Use fresh samples of microbial dolostone from the penecontemporaneous. 2. Exclude samples with nonplanar-anhedral crystals and retain samples with planar-euhedral/subhedral crystals. 3. Exclude samples with ∑REY relatively higher than in neighboring samples. 4. Exclude samples contaminated by noncarbonate phases, and comprehensively analyze the four methods to exclude samples with diagenetic alteration. This method demonstrates an effective model for the future geological applicability of U–Pb dating results of Precambrian carbonates.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"418 ","pages":"Article 107691"},"PeriodicalIF":3.2,"publicationDate":"2025-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143182502","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 late Paleoproterozoic I- and A-type granitoids in the southwestern Tarim Craton, NW China: Implications for post-collisional magmatism and tectonic evolution","authors":"Pei Lv ,&nbsp;Shengyao Yu ,&nbsp;Yinbiao Peng ,&nbsp;Lu Yin ,&nbsp;Bei Xu ,&nbsp;Yongjiang Liu ,&nbsp;Sanzhong Li ,&nbsp;Xiangyu Gao ,&nbsp;Xingzhou Jiang ,&nbsp;Chuanzhi Li","doi":"10.1016/j.precamres.2025.107698","DOIUrl":"10.1016/j.precamres.2025.107698","url":null,"abstract":"<div><div>Granitoids are important components of collisional orogens and record the tectonic evolution of orogenic belts. To better understand the late Paleoproterozoic orogeny in the Tiekelike area, southwestern Tarim Craton, China, we conducted a petrological, geochemical, and zircon U-Pb geochronological and Lu-Hf isotopic study of granitic dyke, quartz monzonite, quartz monzonitic dyke and granitic gneiss. The results show that these granitoids were emplaced between 1.88 and 1.85 Ga and can be divided into two groups. Group 1 (the granitic dyke and gneiss) are I-type granitoids with higher SiO₂ and alkali contents, and Sr/Y ratios, but lower rare earth element contents than the group 2 (the quartz monzonite and quartz monzonitic dyke), which resemble A₂-type granitoids. The I-type granitoids were generated by partial melting of ancient lower-crustal rocks, whereas the A₂-type quartz monzonite and quartz monzonitic dyke were derived by melting of granodiorites under high-temperature and low-pressure conditions. All these late Paleoproterozoic I- and A-type granitoids formed in a post-collisional setting. Integrating our results with previous studies, we propose a model for the late Paleoproterozoic orogenic evolution of the Tarim Craton. The southeastern Tarim Craton (North Altyn Tagh area) first collided with other cratons/blocks at 2.00–1.95 Ga. Subsequently, the unified Tarim Craton was formed by the assembly of the southern and northern Tarim terranes at 1.92–1.90 Ga. Concurrently, the southwestern (Tiekelike area) and northeastern (Kuluketage area) Tarim Craton were also amalgamated with other cratons/blocks. The eastern Tarim Craton (Dunhuang area) then collided with other cratons/blocks at 1.82–1.80 Ga. Finally, the Tarim Craton experienced a high-temperature post-collisional orogeny. The orogeny that affected the Tarim Craton was an integral part of the tectonic evolution of the Columbia supercontinent during the Paleoproterozoic.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"418 ","pages":"Article 107698"},"PeriodicalIF":3.2,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143182500","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":"Regulation of carbon–nitrogen cycle by chemoautotrophic bacteria during the early Cambrian: Evidence from the silicate-bound nitrogen in the Yangtze Block, South China","authors":"Hansheng Cao ,&nbsp;Hanli Huang ,&nbsp;Zaiyun Wang ,&nbsp;Fajin Chen ,&nbsp;Kai Wei ,&nbsp;Qinghua Hou ,&nbsp;Wentong He ,&nbsp;Chunqing Chen","doi":"10.1016/j.precamres.2025.107703","DOIUrl":"10.1016/j.precamres.2025.107703","url":null,"abstract":"<div><div>The Ediacaran-Cambrian (E–C) transition was a critical period in Earth’s history marked by environmental changes and an unprecedented biological evolution event. During the early Cambrian, carbon isotopes (δ¹³C_carb and δ¹³C_org) exhibited multiple large negative excursions. The first and second excursions, known as the Basal Cambrian Carbon Isotope Excursion (BACE) and the Shiyantou Carbon Isotope Excursion (SHICE), are closely associated with the extinction of the Ediacaran biota and the small shelly biota, respectively. While it is hypothesized that intensified anoxic conditions contributed to the perturbations in carbon cycling and life evolution during the early Cambrian, the specific details of the mechanisms behind the negative carbon isotope excursions still require further investigation. Fixed ammonium is incorporated within the crystal structure of silicate minerals (mostly K-bearing phyllosilicates and feldspars) and is also referred to as silicate-bound nitrogen. It is the primary form of inorganic nitrogen in rocks and is increasingly being recognized for its role in reconstructing nitrogen cycles in paleo-oceans. In this study, we conducted detailed geochemical analyses of kerogen-bound nitrogen and silicate-bound nitrogen found in marine sequence from the lower Cambrian strata within the South China Craton. The isotopic composition of kerogen-bound nitrogen overall exhibits a negative excursion, indicating an expansion of the anoxic zone in seawater and a concomitant contraction of the nitrate reservoir during deposition of the Shuijingtuo Formation. The ¹⁵N-depleted signal of kerogen (&lt;0‰) is concurrent with the notably elevated δ¹⁵N_silicate values (up to 9.5 ‰) in the Shuijingtuo Member I, displaying offsets of up to 10.0 ‰. We attribute the abnormally high δ¹⁵N_silicate values to intensified anammox associated with expansive anoxic bottom waters. Our research reveals a strong coupling between marine carbon and nitrogen cycles during the early Cambrian. Insofar as the biomass formed by carbon fixation coupled to ammonium oxidation is significantly depleted in ¹³C relative to CO₂ in the atmosphere due to respiratory processes, the SHICE may be attributed to progressively greater inputs from these chemoautotrophic sources. This new explanation broadens our understanding of the mechanisms controlling the negative excursions of carbon isotopes during the early Cambrian. Furthermore, our results also suggest that applying the δ¹⁵N_kerogen and the δ¹⁵N_silicate proxies, as observed in the lower Cambrian Shuijingtuo Formation, enables speculation on the origin of changes with analogous δ¹⁵N distributions associated with intensified anammox over other time periods.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"418 ","pages":"Article 107703"},"PeriodicalIF":3.2,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143183029","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":"Unravelling the Neoproterozoic oceanic sedimentary record: Insights from the Mona Complex Ocean Plate Stratigraphy, Wales","authors":"Václav Santolík ,&nbsp;Lukáš Ackerman ,&nbsp;David Buchs ,&nbsp;Niall Groome","doi":"10.1016/j.precamres.2025.107708","DOIUrl":"10.1016/j.precamres.2025.107708","url":null,"abstract":"<div><div>Ocean Plate Stratigraphy (OPS) represents a sequence of volcanic and sedimentary rocks of the uppermost part of an oceanic plate typically preserved in tectonic stacks of an accretionary wedge. While the characteristics of Phanerozoic OPS are generally well-known, those of Neoproterozoic OPS, especially their sedimentary components, remain underexplored. We combined field observations with petrography and geochemistry (major and trace elements, Sr–Nd isotopes) of sedimentary rocks from the Gwna Group (Mona Complex, Wales, UK) representing a well-preserved example of Neoproterozoic OPS. The rocks were subdivided into five groups: (1) red chert/jasper, (2) carbonate/dolostone, (3) black mudstone, (4) red/green mudstone, and (5) turbiditic/volcaniclastic rocks. The carbonate rock and red chert fill interpillow spaces or form less than 2-meter-thick layers above a basaltic base. These rocks formed as chemical precipitates from hydrothermal fluid (ε_Nd = −2.4 to −1.2) or hydrothermally fluxed seawater (ε_Nd = −8.3 to −7.4) related to magmatic activity on the seafloor. Unlike Phanerozoic OPS, the studied OPS does not include a thick bedded chert sequence resulting from the accumulation of plankton remains. The red, green, and black mudstones were deposited on the ocean floor in a pelagic or hemipelagic environment under oxygenated and anoxic conditions. They were predominantly sourced from distal mature continental crust as exemplified by their low ε_Nd values (−11.3 to −3.5). In contrast, the turbiditic and volcaniclastic rocks (ε_Nd = −1.9 to +0.8) that form most of the Gwna Group were sourced from an adjacent volcanic arc and deposited in a trench. We show that the OPS lithological and compositional changes relate to Neoproterozoic plate motion and increasing proximity to a subduction zone. The OPS of the Gwna Group serves as a crucial paleooceanographic and paleogeographic indicator in the Neoproterozoic.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"418 ","pages":"Article 107708"},"PeriodicalIF":3.2,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143182506","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Revisiting the geological evolution of the Brasília orogenic belt (Central Brazil) through the integration of tectonic and provenance studies","authors":"Paulo Henrique Amorim Dias ,&nbsp;Humberto Luis Siqueira Reis ,&nbsp;Claudio de Morisson Valeriano ,&nbsp;Joseneusa Brilhante Rodrigues ,&nbsp;Márcio Antônio Silva ,&nbsp;Mariana Meireles Leite ,&nbsp;Caio Alencar de Matos","doi":"10.1016/j.precamres.2025.107693","DOIUrl":"10.1016/j.precamres.2025.107693","url":null,"abstract":"<div><div>The tectonic evolution of ancient collisional orogenic systems can be unraveled using a variety of approaches, including systematic dating and geochemical analysis of pre- to post-collisional magmatic rocks, as well as the study of associated sedimentary basins. The Brasília Orogenic Belt in Central Brazil represents a critical component of the orogenic systems that formed during the assembly of West Gondwana in the Neoproterozoic to early Paleozoic. In this study, we present a reinterpreted tectonic map of the Brasília Orogenic Belt, integrated with regional tectonic sections and a comprehensive dataset of geochronological information. This work involved the compilation, integration, and reinterpretation of detailed and regional geological maps, new field data, seismic and geophysical maps, and hundreds of U-Pb detrital and direct ages from sedimentary successions. Two major tectonic components were recognized and improved: i) pre-orogenic sedimentary basins including a Paleoproterozoic rift, a Mesoproterozoic rift-sag and a Mesoproterozoic to Neoproterozoic rift-sag that evolved into a passive margin; and ii) Ediacaran to Cambrian <em>syn</em>-orogenic basins that include a forearc and a <em>syn</em>-collisional basin. Our data reveal a tectonic evolution pre-dated by multiple Proterozoic rifting episodes that evolved into an ocean-floored and passive margin basin in the Neoproterozoic. The tectonic convergence between the São Francisco and the Paranapanema and Amazonian palecontinents during the Neoproterozoic-early Paleozoic converted the passive margin into a complex accretionary system and, later on, into a collisional orogen. The tectonic architecture and evolution of the belt seem to have been also controlled by preexisting structures, which partially induced the development of contrasting elements in the northern and southern portions of the belt, as well as the preservation of contrasting geological records. Sedimentary provenance patterns observed on pre- to <em>syn</em>-orogenic basin-fill units reflect the availability of cratonic and orogenic sources and the tectonic evolution of individual depocenter. Our work provides new insights into the assembly of West Gondwana and improves our understanding of ancient mountain-building process documented in the geological record.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"418 ","pages":"Article 107693"},"PeriodicalIF":3.2,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143183030","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 tectonic implications of Neoarchean mafic and felsic rocks in western Liaoning: Constraints on the crustal evolution of the northeastern North China Craton","authors":"Xue Chen ,&nbsp;Chenyue Liang ,&nbsp;Franz Neubauer ,&nbsp;Changqing Zheng ,&nbsp;Yongjiang Liu","doi":"10.1016/j.precamres.2025.107700","DOIUrl":"10.1016/j.precamres.2025.107700","url":null,"abstract":"<div><div>The late Archean (3.0–2.5 Ga) marks a significant transformation period in the continental crust and geodynamic processes. Representative Archean records in the North China Craton (NCC), including basaltic rocks, trondhjemite-tonalite-granite (TTG) gneisses and potassic granites, are essential for understanding the formation of the Archean continental crust. The Western Liaoning (WLN) in northern NCC preserves valuable Neoarchean geological records, providing a natural laboratory for studing crustal development and geodynamics. Based on mineralogy, petrology, geochronology, and geochemistry, this study investigates the Neoarchean mafic and felsic rocks in WLN. The 2549–2531 Ma old mafic rocks are derived from partial melting of the ultramafic lithospheric mantle, influenced by crustal contamination and metasomatic exchange with subduction fluids. TTG gneisses dated 2526–2509 Ma are classified as peraluminous calc-alkaline granites, generated by the partial melting of garnet amphibolites in thickened arc root. Potassic granites belong to the weakly peraluminous shoshonite-series are S-type granites, originated from partial melting of upper crustal metamorphic argillaccous rocks. This study also identifies a crustal growth episode in WLN between 2.8 and 2.7 Ga, through a comprehensive analysis of Hf model ages of mafic and felsic rocks. Late Neoarchean geodynamic evolution in WLN involved a transition from mid-ocean ridge (N-MORB-type) to intra-oceanic island arc (boninite-type), then to Andean-type active continental margin (adakite-and high-alumina TTG-type), and ultimately to an extensional tectonic phase (the potassic granite-type). Collectively, WLN preserves a complex geodynamic history of crust-mantle interactions related to subduction during the late Neoarchean.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"418 ","pages":"Article 107700"},"PeriodicalIF":3.2,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143182505","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 Rhyacian-Orosirian basement at the northeastern region of the Araçuaí orogen, Bahia, Brazil: Further evidence of an island-arc accretion followed by syn- and post collisional plutons during the São Francisco-Congo paleocontinent assembly","authors":"Anderson Victoria ,&nbsp;Antonio Pedrosa-Soares ,&nbsp;Simone Cerqueira Pereira Cruz ,&nbsp;Luiz Carlos Silva ,&nbsp;Cristiano Lana ,&nbsp;Elton Dantas ,&nbsp;Luiza Lopes de Araújo","doi":"10.1016/j.precamres.2025.107677","DOIUrl":"10.1016/j.precamres.2025.107677","url":null,"abstract":"<div><div>Granodioritic-tonalitic orthogneisses, together with granodioritic and high-K intrusions compound the Rhyacian-Orosirian basement units in the northeastern region of the Araçuaí belt, northeastern Brazil. These rocks were deformed and metamorphosed during the Neoproterozoic compressive event, but their genesis goes back to the Rhyacian-Orosirian times, when the São Francisco-Congo paleocontinent was amalgamated at the end of the Minas-Bahia orogeny (MBO). Field and petrographic data, twenty-two lithochemical analyses, three U-Pb (LA-ICPMS) zircon ages, zircon-in Lu-Hf and thirteen Sm-Nd analyses were conducted. Additionally, four previous U-Pb (SHRIMP) zircon ages were revised. The crystallization age of 2099 ± 14 Ma obtained for the granodioritic orthogneiss is close to the tonalitic-trondjhemitic granulites of the Buerarema complex in the cratonic interior (ca. 2.19 to 2.10 Ga). This fact, together with the similar lithochemical signatures, compatible with magnesian, calc-alkaline and sodic TTGs magmas, deficient in Nb, Ta, P, Ti, Y, Yb_N and enriched in La_N/Yb_N, suggest the extension of the Buerarema complex towards the interior of the Araçuaí belt, where it was reworked by the Neoproterozoic orogeny. The lithochemical signature observed for these orthogneisses is compatible with subduction-related magmas and the moderately juvenile signatures (ɛHf(t): −0.5 to −4.6; ɛNd(t): −1.6 to −4.6) suggest derivation from intraoceanic mature arcs. The presence of others ca. 2.1 Ga coeval arcs related to the Bahia-Minas orogeny (i.e.: the Rio Itapicuru, Costeiro, Rio Campim, Mineiro, Mantiqueira, Juiz de Fora and other arcs) not only corroborates with the interpretation of the pre-collisional Buerarema arc, but also suggest the presence of an expressive oceanic crust between the Archean blocks at ca. 2.1 Ga. One calc-alkaline and metaluminous granodioritic stock (2067 ± 5 Ma) and new mapped high-K shoshonitic granitoids (2025 ± 7 Ma) are intrusive in the Buerarema complex. Their isotopic record are indicative of crustal evolved rocks (ɛHf(t): −4 to −7; ɛNd(t): −2.8 to −3.0; and ɛHf(t): −7 to −14; ɛNd(t): −2.4 to −2.6, respectively) compatible with syn and post-collisional magmas of the MBO. Although the Paleoproterozoic age, the high content of Ba-Sr in concordance with the elevate ferromagnesian minerals and incompatible trace and REE elements allow the discussion if these intrusions are sanukitoid-like rocks.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"418 ","pages":"Article 107677"},"PeriodicalIF":3.2,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143183031","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}