Precambrian Research最新文献

{"title":"Deformation in the Agnew-Wiluna Greenstone Belt and host Kalgoorlie Terrane during the c. 2675–2630 Ma Kalgoorlie Orogeny: ∼45 Ma of horizontal shortening in a Neoarchean back-arc region","authors":"","doi":"10.1016/j.precamres.2024.107586","DOIUrl":"10.1016/j.precamres.2024.107586","url":null,"abstract":"<div><div>This study re-evaluates the tectonic processes that contributed to the final assembly of the Yilgarn Craton (Western Australia) in the late Neoarchean. We combine regional-scale (10–100 km) geological data collected from surface exposures over the Agnew-Wiluna Greenstone Belt (AWGB) in the Kalgoorlie Terrane of the Eastern Goldfields Superterrane (EGST) together with published and open-file geochronological and structural data from the Geological Survey of Western Australia. The combined datasets are then compared with the structural record in the Kalgoorlie Terrane, allowing for new insights into the tectonic evolution of the EGST and broader Yilgarn Craton. We show that c. 2675–2630 Ma orogenic deformation in the AWGB was associated with a protracted sequence of events, marked by the activation of distinct shear zones through time and repeated shifts in the location of sedimentary depocentres. We propose that the observed strain pattern resulted from the complex interplay of deformation, magmatism, and sediment deposition under progressive, ENE-WSW-directed horizontal shortening spanning ∼45 Ma. We suggest that the identified deformation scheme represents the local expression of tectono-thermal events affecting the Kalgoorlie-Kurnalpi Rift and broader EGST. Building on prior knowledge on the geological evolution of the Yilgarn Craton, our study supports a model proposed more than a decade ago whereby orogenesis was driven by a west-dipping, outboard subduction zone located further east of the exposed margins of the Yilgarn Craton. Lastly, we emphasize that such scale-integrated, unified perspective provides a balanced reconciliation between the debated allochthonous and <em>para</em>-autochthonous models for the EGST.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535572","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":"Linking Neoproterozoic lode gold provinces to a metasomatized mantle source in South China: Evidence from fluid inclusions and H-O-S-Pb isotope systematics","authors":"","doi":"10.1016/j.precamres.2024.107603","DOIUrl":"10.1016/j.precamres.2024.107603","url":null,"abstract":"<div><div>Lode gold deposits are typically formed in fields, belts, or provinces, representing the peak stages of continental crust growth and spanning from the Archean to the Neogene. The Meso- and Neoproterozoic eras represent critical stages of the continental crust growth period. In fact, the formation of lode gold deposits during this period has attracted considerable attention due to their global rarity. Recently, a Neoproterozoic lode gold province, encompassing more than 70 gold deposits/occurrences with over 300 gold veins, has been identified in the Huangling area of South China. Nevertheless, our understanding of the fluid characteristics, source, and evolution governing the formation of Neoproterozoic lode gold provinces remains relatively poor. To address these issues, pyrite-chalcopyrite-gold-dominated quartz veins from four representative deposit areas (Guaizigou, Mahuagou, Hongwucun, and Shuiyuesi) under various rock formations were studied through fluid inclusion and H-O-S-Pb isotope assessments. These fluids exhibited medium–low temperature, medium–low salinity, and an H₂O-NaCl-CO₂ ± CH₄ system. The calculated <em>δ</em>¹⁸O_water and δ¹⁸D_water values of quartz in the ore-forming fluids ranged from −1.7 to + 3.6 ‰ and −74.1 to −40.5 ‰, respectively, suggesting that the ore-forming fluids were derived from a combination of mantle sources, metamorphic water, and meteoric water. The influence of the mantle-derived fluids on the southern gold deposits was significant. Fluids in sulfur isotope equilibrium with pyrite exhibited δ³⁴S_H2S values between + 3.1 and + 6.7 ‰, which is consistent with a mantle origin under crustal influences. The Pb isotopes of pyrite indicated a metasomatized lithospheric mantle origin of the gold deposits in the region, which is similar to local mafic dikes. In addition, the gold deposits are strengthened by crustal contamination progressing from south to north of the Huangling area. According to previous Sr-Nd-C isotope data and multiple isotopic features, the ore-forming fluids and metals were derived from a metasomatized lithospheric mantle in the Neoproterozoic lode gold provinces of South China. The gold deposits interacted with basement rocks through their movement path and ore-forming fluid ascendancy. The fluids might be boiled due to rapid cooling and decompression. Indeed, they experienced mixing with a small amount of meteoric water and ultimately precipitated at secondary faults, leading to gold mineralization.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535573","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 setting of mafic magmatism within the Laguna Amarga Metamorphic Complex, Andes of Catamarca, Argentina: Insights into the opening of the Cuyania/Precordillera terrane from the Ouachita rift","authors":"","doi":"10.1016/j.precamres.2024.107601","DOIUrl":"10.1016/j.precamres.2024.107601","url":null,"abstract":"<div><div>Neoproterozoic crystalline basement rocks are exposed as fault-bounded blocks over the high Andes of Catamarca. The crystalline basement is stratigraphically grouped into the unique Laguna Amarga Metamorphic Complex and represents the northern extension of the Cuyania/Precordillera terrane. Tabular bodies of <em>meta</em>-mafic rocks are widespread in the basement interspersed within a thick sequence of <em>meta</em>-sedimentary rocks derived from siliciclastic, calc-silicate, and limestone protoliths. Overall, the geochemical characteristics of <em>meta</em>-mafic rocks are in the compositional range of Normal-Mid Ocean Ridge Basalt (Normal-MORB), reflecting a common depleted-mantle source with varying degrees of partial melting. While preserving the typical bulk chemistry of MORB magmatism, some mafic magma underwent differentiation at emplacement, leading to the development of high-Ti mafic rocks. New U-Pb zircon geochronology reveals three distinct age peaks, with two coinciding with ages identified in the metasedimentary host rocks. The dominant Mesoproterozoic age cluster is linked to inherited zircon crystals assimilated within a single <em>meta</em>-mafic rock. In contrast, zircon ages from the late Ordovician to early Devonian are attributed to metamorphic overgrowths. Notably, the third age cluster, delineates a Late Neoproterozoic magmatic event, indicating the temporal span of mafic magmatism. The finding agrees with the best available age (576 ± 17 Ma) for mafic magmatism on the Precordillera Mafic-Ultramafic Belt. Stratigraphic relationships and geochemical fingerprints enable correlation among the <em>meta</em>-mafic rocks from Laguna Amarga, tracing a belt of mafic magmatism with an oceanic affinity that extends southward. Building upon previous works, this study reaffirms that the rift-drift transition of the Cuyania/Precordillera terrane, linked to the Ouachita rift opening from southeastern Grenville, evolved during the latest Neoproterozoic.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535570","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":"Detrital zircon and apatite reveal Paleoproterozoic rifting along the eastern margin of the Yilgarn Craton","authors":"","doi":"10.1016/j.precamres.2024.107602","DOIUrl":"10.1016/j.precamres.2024.107602","url":null,"abstract":"<div><div>Detrital minerals within Proterozoic basins are commonly an extant record of now-destroyed crust and provide valuable constraints on ancient paleogeography and tectonic processes. However, reconstructing basin histories depends on discriminating potentially exotic, far-travelled (allochthonous) versus locally sourced (autochthonous) detritus. Detrital zircon from the Woodline Formation, a component of the Proterozoic Barren Basin at the margin of the Yilgarn Craton, Western Australia, closely matches the age and Hf isotopic signatures of magmatic units in the Paleo- to Mesoproterozoic Albany–Fraser Orogen (AFO). However, the provenance of some 2300–2000 Ma zircon detritus is not readily accounted for by known magmatism in the AFO nor the wider Western Australian Craton. To help resolve this enigmatic source, we present isotopic data (U–Pb, Lu–Hf) and trace element geochemistry for zircon and limited U–Pb data for scarce apatite collected from sand and rocks of the Woodline Formation. Based on Hf isotopic signatures, some of the detritus appears to be derived from the recently identified 2030–2010 Ma felsic-igneous Moonyoora Suite, representing the oldest known magmatic components of the AFO. Moreover, the isotopic data imply an earlier ca. 2250 Ma episode of mafic rift-related magmatism, potentially offering a glimpse into the earliest rifting stages along the Yilgarn Craton’s eastern margin. While Paleoproterozoic detritus is omnipresent in Woodline rocks, it is conspicuously absent from overlaying regolith, demonstrating that cover atop the Woodline Formation is imported and not locally derived. This disparity is important as it highlights that ongoing exploration efforts analysing unconsolidated regolith may not fully capture basement signatures.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535571","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":"Petrogenesis of supracrustal rocks from the Maxianshan and Xinglongshan Groups in the eastern Central Qilian block: Constraints on the construction of Rodinia","authors":"","doi":"10.1016/j.precamres.2024.107590","DOIUrl":"10.1016/j.precamres.2024.107590","url":null,"abstract":"<div><div>Controversy has long surrounded the reconstruction of the East Asian blocks in the Rodinia supercontinent, which was a coherent large landmass during 900–750 Ma and is now dispersed over all current major continents. The Central Qilian block is a Precambrian microcontinent in the early Paleozoic Qilian orogenic belt, which marks the junction of the North China, South China and Tarim cratons. In this paper, we present a systematic study of the petrology, whole-rock geochemistry, and geochronology of supracrustal rocks from the Maxianshan Group and the Xinglongshan Group in the easternmost part of the block. The metasedimentary rocks from both groups overlie a gneissic granite, which has a zircon U-Pb age of 970 ± 6 Ma with εHf_(t) values of −3.5 to + 2.5 and is an I-type granite formed in a back-arc setting. Paragneisses from the Maxianshan Group and micaschists from the lower formation of the Xinglongshan Group have detrital zircon U-Pb ages of 2465–876 Ma that peak at <em>ca.</em> 950 Ma. They show strongly decreasing zircon εHf_(t) values of + 0.8 to −11.3 and ages from 1174 Ma to 876 Ma. Their protoliths constituted a sedimentary sequence with a long history of deposition during 1174–911 Ma in a continental arc-related basin. Metabasaltic tuffs from the middle formation of the Xinglongshan Group are tholeiitic with a zircon U-Pb age of 958 ± 9 Ma and indicate a back-arc setting. Metasandstones from the upper formation of the Xinglongshan Group have detrital zircon ages of 2668–732 Ma that peak at 810 Ma and 984 Ma and indicate a passive margin setting. Combining our results with existing data, we propose that the Maxianshan Group and the Xinglongshan Group make up an early Neoproterozoic trench-arc-basin system at a continental margin of Rodinia. Oceanic crust subduction underneath the continent at 1174–896 Ma with formation of a mature continental arc, and continuous subduction from 824 to 735 Ma with opening of the Proto-Tethys Ocean as a back-arc basin are suggested for the formation of the Central Qilian block.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535569","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 Barberton Drilling Project’s Buck Reef Chert core BARB3 – Sedimentary facies and depositional environment of a 3.4 Ga marine platform succession","authors":"","doi":"10.1016/j.precamres.2024.107584","DOIUrl":"10.1016/j.precamres.2024.107584","url":null,"abstract":"<div><div>The ∼ 3.4-billion-years old Buck Reef Chert (BRC) is a ∼ 400 m thick succession of banded chert and iron-formation that has proved to be an important site for the study of Archaean surface processes. It is exceptional in its degree of preservation of primary textures and microbial matter in chert, but full comprehension of its depositional history requires subsurface investigation. As part of the International Continental Drilling Program-funded Barberton Drilling Project a single drill core (BARB3) with a total length of 899 m was obtained from the steeply dipping succession. The BRC overlies an eroded volcanic edifice of shallow intrusive to extrusive felsic volcanic rocks and is separated from overlying ultramafic lapillistone by an ultramafic sill. Drilling commenced in the sill at an angle of ∼ 45° and ∼ 200 m of serpentinised peridotite were intersected. The remaining ∼ 700 m of the core include a variety of sedimentary and minor intrusive mafic to felsic igneous rocks. The chemical sedimentary rocks are dominated by chert and siderite forming four thinly interbedded lithofacies: (1) white chert, (2) granular chert, (3) grey chert/carbonate, and (4) carbonate, largely reflecting marine precipitation under varying physico-chemical conditions of the depositional environment. These facies form three distinct facies associations of shallow-water banded granular chert, banded ferruginous chert and deep-water banded iron-formation, reflecting gradual deepening of the environment in agreement with previous studies. Subordinate facies include carbonaceous matter-rich siliceous shale distributed randomly throughout the succession and thin beds of jaspilite in banded iron-formation. The former reflect blooms of planktonic microbes linked to enhanced nutrient supply and the latter reflect episodes of variation in marine environmental parameters. Both planktonic and benthic microbes were thriving in an acidic, anoxic, shallow-marine platform environment dominated by chert precipitation. Siderite is common in both shallow- and deep-water deposits and is regarded as an early diagenetic precipitate from alkaline pore fluids. Stratiform and cross-cutting veins of botryoidal chert and quartz ± siderite are common and formed from ascending formation waters derived from compaction of chert precursor sediment. Deposition took place in a volcanically active setting with high geothermal heat flow, resulting in early diagenetic thermal decomposition of organic matter and some hydrocarbon generation, now preserved as pyro-bitumen. Exceptional preservation of primary textures provides a remarkable record of processes that operated on a 3.4 Ga marine sedimentary platform.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535567","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":"Coeval TTG and sanukitoid magmatism during the Rhyacian tectonic evolution of the Juiz de Fora Complex (São Francisco Paleocontinent, SE-Brazil)","authors":"","doi":"10.1016/j.precamres.2024.107585","DOIUrl":"10.1016/j.precamres.2024.107585","url":null,"abstract":"<div><div>Transitioning tectonic regimes from stagnant lid to plate tectonic models is still challenging. This tectonic transition appears to be diachronic in different old cratonic blocks worldwide. One key point to address tectonic models in early Earth is the appearance of the TTG-sanukitoid associations, which are interpreted as the products of melting oceanic slabs and melting of the hydrated mantle wedge in supra subduction zones. Although typical of the Archean, this association persists until the Paleoproterozoic in some cratonic remnants of South America. The Minas-Bahia Orogen (MBO) is one of the most extensive Paleoproterozoic belts of Brazil, cropping out in the São Francisco Craton but also as reworked thrust slices within surrounding Neoproterozoic belts. Here, we explore the southern part of MBO, bringing new geochemical, U-Pb zircon geochronology (LA-ICP-MS) and Nd and Sr isotopic data of the Juiz de Fora Complex that constitutes the external magmatic arc system of this Siderian to Orosirian orogen. Granodioritic to tonalitic orthogranulites with TTG geochemical signatures, crystallization ages of ca. 2.21 and 2.14 Ga, with positive εNd_i (+2.9 to + 5.9) and ⁸⁷Sr/⁸⁶Sr_i ratios between 0.7022 and 0.7045; Quartz-dioritic to granodioritic orthogranulites with sanukitoid composition, displaying crystallization ages between ca. 2.21 and 2.18 Ga, with near-chondritic εNd_i values of −2.43 to + 0.39, and ⁸⁷Sr/⁸⁶Sr_i ratios between 0.7076 and 0.7179. Integrating the new data with previously published analyses allows us to envisage a comprehensive tectonic evolution model starting in an intra-oceanic setting and progressively evolving to a continental magmatic arc environment along the Rhyacian period. Integrated geochronology data indicates coeval and continuous generation of TTG and sanukitoid magmas for 160 Myr. Initially, with more juvenile contribution (ca. 2.22–2.15 Ga), that evolves progressively to a more mature stage (2.15––2.06 Ga). Additionally, two groups of mafic rocks, with ages of ca. 2.16 (OIB-like) and ca. 2.14 Ga (E-MORB), fill the gap between these two stages and possibly reflect arc migration and upwelling of the asthenosphere. Finally, data suggests the operation of plate tectonic processes since the Rhyacian, within this accretionary segment of the MBO, that ultimately resulted in the building of the São Francisco Paleocontinent.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535568","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":"Comment on “Late Archean sedimentary basins in the northeastern Superior Province, Canada: Plume-generated crustal tears or syn-convergent accretionary belts?”","authors":"","doi":"10.1016/j.precamres.2024.107587","DOIUrl":"10.1016/j.precamres.2024.107587","url":null,"abstract":"","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142442016","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 Precambrian eclogites in the Belomorian Province, eastern Fennoscandian Shield","authors":"","doi":"10.1016/j.precamres.2024.107579","DOIUrl":"10.1016/j.precamres.2024.107579","url":null,"abstract":"<div><div>This study focuses on a boudin of Archean amphibolite that occurs in the Gridino eclogite-bearing mélange (Belomorian Province, eastern Fennoscandian Shield) and contains two varieties of eclogite. Eclogite-1 is banded, retrogressed (omphacite is totally replaced by clinopyroxene-plagioclase symplectite), and deformed by recumbent tight folds identical to those in the TTG-amphibolite host. Zircon groups are dated at 2721 ± 26 Ma (Zrn-I, fir-tree zoning, no or small negative Eu anomalies, flat HREE patterns, 700–730 °C, 14–15 kbar), <em>ca.</em> 2.70 Ga (Zrn-II, rims around Zrn-I, grains, 750–900 °C, 11–14 kbar, high-<em>P</em> granulite facies), and <em>ca.</em> 2.70 Ga (Zrn-III, rims around Zrn-II). Newly formed Paleoproterozoic zircon crystals are lacking. Retrogressed eclogite-1 in which amphibolization and epidotization totally obliterated garnet and plagioclase-clinopyroxene symplectites is intruded by 2646 ± 46 Ma old granodiorite. Eclogite-2 is massive, contains preserved omphacite-garnet-quartz-rutile assemblages, and comprises two patches whose boundaries truncate folds in eclogite-1. A Paleoproterozoic age of eclogite-2 is evidenced by previously published 1.90 Ga ages of zircon rims around Archean zircon and newly formed crystals with omphacite inclusions. The largest patch contains tabular enclaves of three varieties of amphibolites. One variety is identical to some bands of totally retrogressed eclogite-1 changed into monomineral amphibolites in both the Neoarchean and Paleoproterozoic. The orientation and attitude of these tabular enclaves are coherent with those of the banding on limbs of recumbent tight folds in eclogite-1 within the boudin and later drag folds at its margins and form one and the same structural carcass or skeleton. These data along with recent findings of inherited 2.68 Ga old zircon with inclusions of omphacite in eclogite-2 indicate that this eclogite developed after Neoarchean eclogite-1 due to fluid infiltration along reactivated Neoarchean shear zones enveloping the boudin. These results favor the idea that the transition to the modern-style plate tectonics started not later than in the Neoarchean.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142423601","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 Tonian (c. 735 Ma) A-type granite magmatism on the passive margin of the São Francisco paleocontinent was coeval with outboard subduction","authors":"","doi":"10.1016/j.precamres.2024.107578","DOIUrl":"10.1016/j.precamres.2024.107578","url":null,"abstract":"<div><div>Late Tonian (ca. 735 Ma) A-type granite magmatism accompanied the development of a rifted continental margin in the southwestern portion of the São Francisco paleocontinent. Zircon U-Pb and trace elements, whole-rock lithogeochemistry, and Nd-Sr isotopes enable assessment of the tectonic setting. The Araras Granite shows high silica content (between 73 and 76 %) and ferroan character. The Y + Nb and Yb + Ta parameters vary respectively between 73 to 212 ppm, and 8.3 to 19.1 ppm, and the 1000*Ga/Al ratio varies between 2.6 and 3.4. Zircon U-Pb data indicates a crystallization age of 736 ± 12 Ma. The εNd_(t) is slightly negative (between −3.6 and −1.7), and the depleted mantle model ages (T_DM) range between 1.26 and 1.56 Ga. Binary mixing models based on whole-rock element and isotope geochemistry indicate that the granite was formed by mixing melts derived from two sources: a lithospheric mantle component and Paleoproterozoic magmatic arc rocks from the regional basement. The Araras Granite is concluded to represent a late stage of extension-related intraplate magmatism between ca. 840 and 730 Ma, associated with the evolution of a rifted continental margin in the southwestern São Francisco paleocontinent. Intraplate magmatism was partially synchronous with documented magmatic pulses within long-lived island arc systems that surrounded the paleocontinent. Extensional episodes in the rifted passive margin may be related to slab-pull forces driven by the outboard subduction dynamics.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142357339","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}