Precambrian Research最新文献

{"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}

{"title":"Rift metamorphism of bimodal magmatic rocks during breakup of supercontinent Rodinia","authors":"Qiang He,&nbsp;Yong-Fei Zheng,&nbsp;Shao-Bing Zhang,&nbsp;Ren-Xu Chen","doi":"10.1016/j.precamres.2025.107877","DOIUrl":"10.1016/j.precamres.2025.107877","url":null,"abstract":"<div><div>The identification of supercontinental breakup processes in fossil continental rift zones is crucial for the reconstruction of supercontinents. However, it remains a challenge due to intensive obliteration by later geological events. In general, supercontinental breakup is realized through successful continental rifting, developing from lithospheric rupturing to seafloor spreading. It is closely associated with asthenospheric upwelling in both space and time, leading to enhancement of both conductive and advective heat transfers from the asthenospheric mantle through the lithospheric mantle into the continental crust. This gives rise to bimodal magmatism, high-temperature (high-T) water–rock reaction, and rift metamorphism at high geothermal gradients. Although such abundant processes are substantial to study supercontinental breakup, it is difficult to decipher the sequence of their operation that provides valuable clues for the relationship between magmatism and metamorphism during continental rifting. This issue is addressed by the present study of petrology and geochronology for plagioclase amphibolite and metagranite from the northern margin of the South China Block. This margin was successfully rifted from supercontinent Rodinia in the middle Neoproterozoic, making it suitable for studying rifting-related processes. The protoliths of the plagioclase amphibolite and metagranite are the bimodal magmatic rocks that formed during the supercontinental breakup in the middle Neoproterozoic. They experienced high-T hydrothermal alteration by continental glacier meltwater at first, and then were re-heated to undergo high-temperature/low-pressure (high-T/low-P) metamorphism during the continental rifting. The plagioclase amphibolites record high geothermal gradients of ca. 50 °C/km, and the metagranites preserve higher geothermal gradients of &gt; 80 °C/km since muscovite in the metagranites was dehydrated to form metamorphic andalusite during further decompressional heating. The two kinds of metamorphic rocks were produced at the high geothermal gradients, corresponding to high T/P Buchan type amphibolite facies characteristic of continental rifting along divergent plate margins and continental rift zones. The bimodal magmatism, high-T hydrothermal alteration and high-T/low-P metamorphism would operate sequentially over an interval of approximately 20 Myr, revealing that the bimodal magmatism and the high-T/low-P metamorphism are the two manifestations of regional thermal anomaly due to lithospheric extension during the supercontinental breakup. Therefore, the lithospheric extension plays a significant role in driving the rift metamorphism.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"427 ","pages":"Article 107877"},"PeriodicalIF":3.2,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144632648","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 Neoarchean magmatism and Paleoproterozoic metamorphism in the northern Yangtze Craton: Evidence from high-pressure mafic granulites of the Muzidian complex in the Dabie Orogen","authors":"Xianbin Lu ,&nbsp;Yuanbao Wu ,&nbsp;Guangyan Zhou ,&nbsp;Yujie Zhao ,&nbsp;Bin Xia","doi":"10.1016/j.precamres.2025.107878","DOIUrl":"10.1016/j.precamres.2025.107878","url":null,"abstract":"<div><div>Deciphering metamorphic evolution of high-pressure granulites developed in Palaeoproterozoic orogenic belt is crucial to understand plate tectonic mechanisms and evolutionary history in ancient cratons. In this study, we reported newly found mafic granulites from the Muzidian outcrop, which preserve a clockwise pressure–temperature-time (<em>P–T</em>–t) path. The prograde stage was suggested by inclusions of amphibole, plagioclase, quartz and clinopyroxene in garnet; the peak high pressure granulite facies stage was evidenced by garnet, clinopyroxene, amphibole, plagioclase, quartz and ilmenite, which was constrained in a <em>P–T</em> regime of 10.5–11.0 kbar/860–890 ℃. An early retrograde stage was recorded by orthopyroxene replacing clinopyroxene at <em>P–T</em> conditions of 5.5–7.0 kbar/820–850 ℃, while a later retrograde stage was revealed by the intergrowth of amphibolite and plagioclase in matrix at <em>P–T</em> conditions of 4.6–6.2 kbar/704–778 ℃. Zircon U-Pb dating for the mafic granulites yielded two age groups of ∼2.5 and 2.0 Ga, representing the formation ages of the magmatic protolith and the high pressure (HP) granulite facies metamorphism, respectively. The magmatic protolith zircons exhibit ɛ_Hf(t) values from −8.3 to −0.9 with single-stage Hf model ages of ca. 3.1–2.8 Ga and high δ¹⁸O values from 9.39 ± 0.18 ‰ to 11.58 ± 0.11 ‰. These suggest the protoliths of the mafic granulites were likely derived from an enriched mantle that had been metasomatized by subducted crusatal materials. The metamorphic zircons have ɛ_Hf(t) values from −8.6 to −0.3 and lower δ¹⁸O values from 8.11 ± 0.11 ‰ to 8.80 ± 0.15 ‰, suggesting that the metamorphosed zircons were formed at the granulite-facies metamorphism stage with external low δ¹⁸O and high ɛ_Hf(t) melt/fluid. The clockwise <em>P–T</em>–t paths of the HP granulites suggest that the ca. 2.0 Ga arc-continent collision in the Yangtze craton has extended northward to the North Dabie Zone (NDZ). The Yangtze Craton might be situated in a key tectonic position between the southern margin of the Siberian Craton and the northern margin of Laurentia during the amalgamation of the Columbia supercontinent.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"427 ","pages":"Article 107878"},"PeriodicalIF":3.2,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144632649","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":"970–840 Ma magmatic records from the Douling Complex: Insights into Tonian Subduction-Accretionary and collisional processes in the northern Yangtze Block","authors":"Xiaoying Liao,&nbsp;Tong Li,&nbsp;Liang Liu,&nbsp;Yongsheng Gai,&nbsp;Wenqiang Yang,&nbsp;Tuo Ma,&nbsp;Sang Wan Pak","doi":"10.1016/j.precamres.2025.107876","DOIUrl":"10.1016/j.precamres.2025.107876","url":null,"abstract":"<div><div>Tonian subduction-accretionary and collisional records are fundamental for elucidating the tectonic evolution of the northern Yangtze Block. The Douling Complex along the northern margin of the Yangtze Block preserves key Neoproterozoic records. However, due to the limited exposure of Tonian magmatic rocks, the tectonic regime during this period remains ambiguous. In this contribution, we present new geochronological, geochemical, and isotopic data from amphibolites, mica schists, and gneissic diorite<em>–</em>granodiorites from the Douling Complex. The amphibolites yield protolith ages of ca. 970<em>–</em>920 Ma, representing the earliest Neoproterozoic magmatic event identified in the Douling Complex. These amphibolites exhibit tholeiitic affinities, low Th/Nb and Th/Zr ratios, and positive whole-rock <em>Ɛ</em>_Nd(t) values (+3.39 to + 5.12) and zircon <em>Ɛ</em>_Hf(t) values (+3.8 to + 11.1), indicating a depleted mantle source. Two groups are distinguished: Group I (ca. 920 Ma) displays E-MORB affinities and higher TiO₂ contents, and is spatially associated with mica schist, suggesting formation in a subduction-related back-arc basin; Group II (ca. 970 Ma) exhibits N-MORB signatures with lower TiO₂ contents, interpreted as remnants of oceanic crust. The gneissic diorite/granodiorites are dated at ca. 850<em>–</em>840 Ma. The ca. 850 Ma gneissic diorites are characterized by LILE and LREE enrichments, HFSE depletions, and variable zircon <em>Ɛ</em>_Hf(t) values ranging from –4.5 to + 7.7, indicating derivation from partial melting of juvenile crust with recycled components. The ca. 840 Ma gneissic granodiorites exhibit calc-alkaline compositions, low MgO, Ni, and Cr concentrations, and high Sr/Y ratios with TTG-like affinities. Their highly negative zircon <em>Ɛ</em>_Hf(t) values (–15.1 to –12.5) and Neoarchean T_DM2 model ages (2.51<em>–</em>2.67 Ga) imply significant reworking of Archean continental crust in a subduction-related setting. Additionally, amphibolite-facies metamorphism at ca. 821–813 Ma is recorded in unzoned zircon domains, characterized by pronouncedly steep HREE patterns, negligible or slightly negative Eu anomalies, and formation temperatures ranging from 611 to 714 °C. Combined with regional Neoproterozoic data from the northern Yangtze block, we propose a successive of subduction–accretionary and collisional processes occurred along the Bikou–Xiaomoling–Douling suture zone during the Tonian period.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"427 ","pages":"Article 107876"},"PeriodicalIF":3.2,"publicationDate":"2025-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144605208","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 Konse Group on the SE margin of the Tanzania Craton − a Paleoproterozoic passive margin succession of the Usagaran Orogen: Constraints from metamorphic monazite ages and isotopically heavy carbon in marbles","authors":"Schenk V. ,&nbsp;Bekker A. ,&nbsp;Schmitt A.K.","doi":"10.1016/j.precamres.2025.107874","DOIUrl":"10.1016/j.precamres.2025.107874","url":null,"abstract":"<div><div>The Konse Group is a 2–3 km thick succession of quartzites, metaconglomerates, micaschists, marbles, Mn-rich metasediments and mafic metavolcanics deposited over &gt;200 km in a narrow basin along the SE margin of the Archean Tanzania Craton. The timing of basin formation with respect to the Paleoproterozoic Usagaran orogeny is controversial: it is interpreted either as post-orogenic, overlying folded Usagaran gneisses, or as pre-orogenic, developed on the craton margin. In the latter case, the Konse Group is regarded as a lower-grade, time equivalent of the tectonically overlying Usagaran gneisses, which represent the deeper part of the same basin. Nearly U-free monazite from oxidized Mn³⁺-rich Konse Group micaschists yielded a Th-Pb age of 2028 ± 15 Ma (95 % confidence) for metamorphism, which argues against a post-orogenic depositional age. The low U content and Mn³⁺-enrichment are attributed to oxidizing conditions in the precursor sediment. The pre-Usagaran depositional age is supported by highly positive δ¹³C values, +12.6 and +9.3 ‰, for marbles of the Konse Group and correlative Mpwapwa Group to the northeast, respectively, indicating sedimentation during the ca. 2.22–2.06 Ga Lomagundi Event. Both groups share a similar depositional age and tectonic setting with marginal successions of other southeastern African cratons, which were deposited at early stages during the assembly of the Paleoproterozoic Columbia/Nuna supercontinent. The Konse and Mpwapwa groups represent cratonic passive margin successions, which belong to the Usagaran Orogen. The latter contains essential lithological members of a Wilson cycle, suggesting that modern-style plate tectonics operated during the Paleoproterozoic.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"427 ","pages":"Article 107874"},"PeriodicalIF":3.2,"publicationDate":"2025-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144580754","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":"Continental-scale carbonate sedimentation and environmental correlates of the Shuram-Wonoka excursion","authors":"Daniel C. Segessenman ,&nbsp;Shanan E. Peters","doi":"10.1016/j.precamres.2025.107875","DOIUrl":"10.1016/j.precamres.2025.107875","url":null,"abstract":"<div><div>Strata of the Ediacaran Period record many Earth-Life features that distinguish the Neoproterozoic-Phanerozoic transition. However, it is difficult to determine cause and effect relationships between Ediacaran events. Here we focus on quantitative properties of carbonate rock area, volume, geochemistry, and depositional environments from the North American Ediacaran System. Patterns of carbonate sedimentation and geochemistry are broadly coincident with transgressive/regressive cycles which have been linked to glacioeustacy and global/regional tectonic forcings of Gondwana amalgamation, continent-facing subduction, and late-stage Rodinia rifting. Highly negative carbonate carbon isotope values distinguishing the Shuram-Wonoka carbon isotope excursion (SW-CIE) coincide with a marked increase in carbonate quantity (&gt;55–60 % dolostone), which spans nearshore, outer shelf, and slope/basin depositional environments. This increase in the extent of carbonate sedimentation on the continent likely indicates marine transgression and appears to be stratigraphically bounded by glacially influenced strata associated with the Gaskiers and the Luoquan/Hankalchough glaciations. This same increase in carbonate sedimentation is also broadly coincident with the first occurrences of the Ediacaran biota. A subsequent pulse in carbonate rock quantity in the latest Ediacaran, dominantly deposited in nearshore environments, coincides with the appearance of biomineralizers, potentially indicating common cause drivers for the extent of shallow marine shelves, carbonate sedimentation, and macroevolution. A comprehensive macrostratigraphic framework for the Ediacaran provides a temporally, spatially, and environmentally explicit context for major biological and geochemical episodes and serves as a platform for future hypothesis testing at the dawn of animal life.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"427 ","pages":"Article 107875"},"PeriodicalIF":3.2,"publicationDate":"2025-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144572721","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":"Tubular microfossils from Neoproterozoic cap limestone of the Dzhetym Group, Kyrgyzstan","authors":"Moore K.R. ,&nbsp;Dawson J. ,&nbsp;Nelson L.L. ,&nbsp;Smith E.F. ,&nbsp;Pruss S.B.","doi":"10.1016/j.precamres.2025.107873","DOIUrl":"10.1016/j.precamres.2025.107873","url":null,"abstract":"<div><div>The Neoproterozoic microfossil record provides a window into the evolution and diversification of the marine biosphere during a dynamic interval in Earth history. Over the course of the Neoproterozoic, the Earth experienced two global glaciations followed by intense warming intervals, a potential rise in atmospheric oxygen, and perturbations to the geochemical cycles of C, Si, and Fe, among others. Generally coincident with these global environmental changes, the biosphere saw key evolutionary and ecological changes that included a rise in marine eukaryotic algae, increased diversity of the marine biosphere, and the appearance of increasingly complex organisms. Although broad evolutionary trends have been documented, further investigation of individual Neoproterozoic microfossil assemblages from across the globe are needed to better constrain evolutionary and ecological changes and how they relate to changing marine environments.</div><div>Here, we present a new microfossil assemblage preserved in black limestone of the Dzhetym Group from the Naryn Region of Kyrgyzstan that directly overlie a glacial diamictite. These microfossils are hollow, tube-shaped structures of ∼25 µm in diameter composed of silica and iron. The structures also contain kerogen that is chemically distinct from the bulk kerogen preserved in the limestone matrix. Based on the composition and morphology of the structures and their preservation by silica and iron, we suggest that they represent microfossils preserved through a previously uncharacterized taphonomic window in a carbonate-dominated Neoproterozoic marine environment. Characterization of these microfossils, as well as the taphonomic mechanisms that facilitated their preservation, expands our understanding of the Neoproterozoic marine biosphere and the potential chemical and biological processes that facilitated microfossil preservation in the aftermath of a glaciation.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"427 ","pages":"Article 107873"},"PeriodicalIF":3.2,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144570657","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":"Sedimentary architecture of the ediacaran mixed carbonate-siliciclastic system, NW arabian plate: Regionally extensive marine incursion or syntectonic fault-controlled basin?","authors":"Muhammad Hammad Malik ,&nbsp;Arif Hussain ,&nbsp;Ardiansyah Koeshidayatullah ,&nbsp;Justin V. Strauss ,&nbsp;Adhipa Herlambang ,&nbsp;Abdulwahab M. Bello ,&nbsp;Khalid Al-Ramadan","doi":"10.1016/j.precamres.2025.107872","DOIUrl":"10.1016/j.precamres.2025.107872","url":null,"abstract":"<div><div>Ediacaran sedimentary successions worldwide are commonly characterized by mixed siliciclastic-carbonate deposits exhibiting contemporaneous deposition. In NW parts of the Arabian plate, a similar style of sedimentation is observed within a series of isolated basins along the NW-trending Najd Fault System. Two contrasting depositional models have been proposed to explain the formation of Km-thick Ediacaran sedimentary sequences in the region, from regionally extensive marine platform to fault-controlled basins with syntectonic deposition. To date, this question remains unanswered and the controlling factors governing the mode of formation, the evolution and the sedimentary architecture for these Ediacaran sequences remain enigmatic. In this study, we explore this mixed siliciclastic and carbonate sedimentation by conducting detailed sedimentology and stratigraphic analysis of the Ediacaran Dhaiqa basin, a transtensional basin formed along the Najd Fault system of western Saudi Arabia. Eight sedimentary facies are identified, ranging from polymict conglomerate to microbial carbonate which most likely represent accumulation in continental (alluvial to lacustrine) to marginal marine settings. In addition to sedimentological evidences for <em>syn</em>-sedimentary tectonic activity, we observed four 3rd-order fining- and deepening-upwards sequences, which may suggest multi-stage, fault-controlled sedimentation related to local tectonic activity in the Dhaiqa basin. Variations in sequence arrangement and thickness further indicate discrete fluctuations in the development of local accommodation space in the basin. These findings highlight how the style of sedimentation in the Ediacaran basins of the Arabian-Nubian Shield may be primarily controlled by local fault-related accommodation, which might differ from many Ediacaran successions that record relative and eustatic base level changes, but is similar to the basins formed in the regions influenced by tectonism. Such information provides a better framework to compare Ediacaran rocks across multiple isolated basins spread across the northwestern regions of the Arabian-Nubian Shield, and may provide base for the future correlations of these sequences with mixed siliciclastic carbonate successions in similar <em>syn</em>-tectonic basins worldwide.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"427 ","pages":"Article 107872"},"PeriodicalIF":3.2,"publicationDate":"2025-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144549668","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":"Unraveling recycling and climate influence on detrital U-Pb geochronology of titanite and apatite: An example from the Gaskiers Glaciation in Newfoundland","authors":"Nicolas Gómez ,&nbsp;David Lowe ,&nbsp;Sebastian Kommescher ,&nbsp;Andrea Mills","doi":"10.1016/j.precamres.2025.107871","DOIUrl":"10.1016/j.precamres.2025.107871","url":null,"abstract":"<div><div>Detrital zircon geochronology is a valuable tool for detecting changes in sediment provenance. However, fertility and reworking biases can obscure the identification of distinct detritus sources during glaciation in complex tectonic settings. Apatite and titanite U-Pb geochronology offers a more versatile option, covering a more comprehensive range of host rocks and closure temperature conditions, although weathering and diagenesis majorly affect mineral stability. Decoupling between multi-proxy age spectra and associated trace element variations provides an opportunity to elucidate the effects of glacial conditions on mineral stability and preservation. Here, we used detrital apatite and titanite U-Pb geochronology and trace element geochemistry from Ediacaran glaciogenic strata of the Gaskiers Glaciation in the Bonavista Peninsula of Newfoundland (Avalon Zone) to better understand sediment recycling and source-to-sink dynamics during glacial events.</div><div>Apatite age spectra from the ca. 590 Ma fluvio-glacial Jones Pond and Plate Cove East members yield dominantly 660–630 Ma U-Pb apatite ages. In contrast, apatite spectra from the ca. 590–580 Ma proximal glaciomarine Monk Bay Member and the overlying ca. 580 Ma deglacial Trinity Diamictite are dominated by ca. 600–580 Ma grains, closely approximating depositional ages. The paucity of Ediacaran detrital apatite in periglacial conglomerates compared to their presence of these grains in deglacial strata reflects their preferential dissolution under acidic weathering conditions, implying the advance of glaciers over the Avalonian catchment from ca. 590 to 580 Ma.</div><div>Detrital titanite preserves Archean, Mesoproterozoic, and Tonian single-grain U-Pb ages throughout the same succession, corroborating contributions from older sources within the otherwise Cryogenian–Ediacaran volcanic arc-dominated West Avalonia assemblage. Long-transported detritus is rare, whereas polycyclic apatite and titanite in the studied units indicate a direct sedimentary link between the underlying Connecting Point Group and its Baltican and/or Amazonian cratonic basement sources. Furthermore, detrital titanite results suggest hydrothermal activity and low-grade metamorphic overprints of ca. 540 and 400 Ma, the latter akin to the Acadian Orogeny that affected West Avalonia.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"427 ","pages":"Article 107871"},"PeriodicalIF":3.2,"publicationDate":"2025-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144523006","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 discovery of Paleoarchean-Mesoarchean magmatic rocks in eastern Hebei, North China Craton: Petrogenesis and tectonic environment","authors":"Chunyan Dong ,&nbsp;Pengchuan Li ,&nbsp;Allen P. Nutman ,&nbsp;Hangqiang Xie ,&nbsp;Shoujie Liu ,&nbsp;Yuan Li ,&nbsp;Dunyi Liu ,&nbsp;Yusheng Wan","doi":"10.1016/j.precamres.2025.107870","DOIUrl":"10.1016/j.precamres.2025.107870","url":null,"abstract":"<div><div>We report the field geology, SHRIMP U-Pb zircon dating, Nd-Hf-O isotopic analysis, and whole-rock geochemical study of Paleoarchean-Mesoarchean magmatic rocks newly discovered over a distance of ∼1 km in the Labashan area, eastern Hebei, North China Craton. The ages obtained for the magmatic zircons from TTGs, potassic granites and <em>meta</em>-gabbros can be divided into two groups: 3513–3381 Ma and 3124–2960 Ma. Thus, combined with previous studies, several periods of magmatism have been documented at 4.0–3.9 Ga, 3.84–3.75 Ga, ca. 3.6 Ga, 3.51–3.38 Ga, 3.12–2.96 Ga and 2.50 Ga in the area. The TTG rocks include tonalitic and trondhjemitic gneisses, showing large variations in REE patterns, with ΣREE (total REE), (La/Yb)_n and Eu/Eu* being 65.8–356.6 ppm, 26.1–195.1 and 0.26–1.83, respectively. The potassic granites include monzogranitic and syenogranitic gneisses, they also show large variations in ΣREE (59.4–238.5 ppm), (La/Yb)_n (17.81–106.14) and Eu/Eu* (0.25–1.11). The <em>meta</em>-gabbros and chlorite-biotite-hornblende schists (<em>meta</em>-mafic rocks) have similar REE patterns, with ΣREE, (La/Yb)_n and Eu/Eu* being 34.0–50.8 ppm, 1.80–3.83 and 0.87–0.96, respectively. Most rocks have negative whole-rock ε_Nd(t) and zircon ε_Nd(t) values, with Nd and Hf model ages commonly being &gt; 3.6 Ga. Magmatic and recrystallized zircons from TTG and <em>meta</em>-gabbro have δ¹⁸O values of 4.69–7.03 ‰ and 4.67–6.17 ‰, respectively, whereas those from potassic granite show larger δ¹⁸O variations from 3.15 to 9.36 ‰. The magmatic rocks show large variations in chemical and isotopic compositions, suggesting that they are derived from different source regions under different conditions, with TTG rocks being formed under medium–low pressure conditions and some potassic granites being derived from or involved with <em>meta</em>-sedimentary rocks in their petrogenesis. It is proposed that both the Paleoarchean and Mesoarchean magma-tectonothermal events occurred via underplating of older crust.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"427 ","pages":"Article 107870"},"PeriodicalIF":3.2,"publicationDate":"2025-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144501318","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}