Precambrian Research最新文献

{"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":"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}

{"title":"Pb-Pb age of Vanivilas carbonates of the Chitradurga group − significance to the timing of emergence of continental crust of the Dharwar Craton","authors":"Ushasi Daripa,&nbsp;S. Balakrishnan,&nbsp;Rajneesh Bhutani,&nbsp;Nanila Sasi,&nbsp;A.Vipin Govind","doi":"10.1016/j.precamres.2025.107868","DOIUrl":"10.1016/j.precamres.2025.107868","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Marine, chemically precipitated carbonate rocks are scarce in Archean cratons, yet they provide crucial geochemical archives for reconstructing early ocean–atmosphere evolution. The Vanivilas Formation in the Chitradurga greenstone belt of the Dharwar craton, represents one such carbonate sequence, offering insights into seawater chemistry, depositional conditions, and post-depositional alteration. Determining the precise age of Archean carbonate rocks is challenging, and is usually constrained by zircon ages of underlying and overlying magmatic rocks. The age of Vanivilas carbonates remains unknown and is considered to be older than 2.7 Ga based on magmatic zircon ages from the younger Ingaldhal Formation. In this study, we integrate Pb isotopic analyses and REE + Y systematics, to constrain the age of the Vanivilas carbonates Formation using Pb-Pb isotope system. Three carbonate samples from outcrops of the Vanivilas Formation yielded isochrons corresponding to ages of 2801 ± 22 Ma, 2621 ± 33 Ma, and 2648 ± 37 Ma, marking distinct geological episodes. The Pb-Pb age of 2801 ± 22 Ma represents the time of diagenesis, predating the U-Pb zircon ages of the overlying felsic volcanic rocks of the Ingaldhal Formation and postdating the detrital zircon ages reported from the underlying phyllites, thereby refining the depositional chronology of the Vanivilas Formation. REE + Y signatures confirm a marine origin, characterized by LREE depletion, HREE enrichment, superchondritic Y/Ho ratios (&gt;49), and positive Eu&lt;sub&gt;SN&lt;/sub&gt;, La&lt;sub&gt;SN&lt;/sub&gt;, and Gd&lt;sub&gt;SN&lt;/sub&gt; anomalies, indicative of a hydrothermally influenced, seawater composition. The absence of a Ce anomaly suggests that the Chitradurga Sea remained largely anoxic, consistent with prevailing Archean Ocean conditions.&lt;/div&gt;&lt;div&gt;The younger Pb-Pb ages (2621 ± 33 Ma and 2648 ± 37 Ma) coincide with the intrusion of K-rich granites (∼2.62 Ga) in and around the Chitradurga greenstone belt indicating isotopic resetting of the Pb-Pb ages. Thorogenic Pb isotope diagram (&lt;sup&gt;208&lt;/sup&gt;Pb/&lt;sup&gt;204&lt;/sup&gt;Pb vs. &lt;sup&gt;206&lt;/sup&gt;Pb/&lt;sup&gt;204&lt;/sup&gt;Pb) reveal distinct evolutionary trajectories: GDK-1 preserves primary diagenetic signatures in a structurally closed system, whereas GDK-2 and KNK experienced Pb mobilization. Thorogenic Pb (&lt;sup&gt;208&lt;/sup&gt;Pb/&lt;sup&gt;204&lt;/sup&gt;Pb) ratios and low κ (&lt;sup&gt;232&lt;/sup&gt;Th/&lt;sup&gt;238&lt;/sup&gt;U) values further supports minimal Pb input from continental sources, reinforcing a seawater-derived Pb isotope signature. These findings place time of deposition of the Vanivilas carbonates within a well-established 2.8 Ga cluster of Archean marine carbonates, comparable to those in Canada and Zimbabwe.&lt;/div&gt;&lt;div&gt;The emergence of continental crust, driven by Tonalite Trondhjemite and Granodiorite (TTG) magmatism (∼3.3–3.0 Ga old) in the western Dharwar Craton, increased freeboard, and enhanced silicate weathering that contributed bicarbonates to seawater, influencing carbonate precipitati","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"427 ","pages":"Article 107868"},"PeriodicalIF":3.2,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144501317","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":"Neoarchean–Paleoproterozoic magmatic–metamorphic events and its tectonic implications of the Zuoquan–Zanhuang metamorphic complexes in the North China Craton","authors":"Ling-Ling Xiao ,&nbsp;Jia-Yi Zhou ,&nbsp;Yi-Lin Liu ,&nbsp;Guo-Dong Wang","doi":"10.1016/j.precamres.2025.107866","DOIUrl":"10.1016/j.precamres.2025.107866","url":null,"abstract":"<div><div>The global felsic continental crust mostly formed during the period of early to middle Neoarchean, and most of cratons worldwide are characterized by the well-developed tectono-thermal event of ca. 2.7 Ga. Abundant geochronological data indicated that the North China Craton (NCC) was predominated by the tectono-thermal event of ca. 2.5 Ga different from many other cratons. However, isotopic studies revealed that the ca. 2.5 Ga granitoids generally formed through reworking of 2.9–2.7 Ga continental materials, and more ca. 2.7 Ga magmatic rocks and zircons have been progressively identified in some areas of the NCC in recent years. These data, therefore, prompted geologists to reconsider the importance of the ca. 2.7 Ga tectono-thermal event in the NCC. The Zuoquan and Zanhuang metamorphic complexes are adjacent and both located in central NCC. Isotopic geochronology and rare earth element analyses of zircons in this study reveals two meaningful groups of magmatic ages, i.e., 2774–2700 Ma and 2519–2496 Ma, recorded in the two complexes. The older age group predominated in the Zuoquan complex which represented an early to middle Neoarchean magmatic event and were generally interpreted to be attributed to a mantle plume or superplume mechanisms. The ages of 2519–2496 Ma were commonly recorded by rocks in the Zanhuang area, representing a regional late Neoarchean magmatic event. Two groups of metamorphic ages (2519 Ma and 1854 Ma) were also recorded by the Zuoquan and Zanhuang metamorphic rocks, respectively. The former, accompanied by the late Neoarchean magmatic event, was probably related to underplating of mantle-derived magmas. The 1854 Ma metamorphic age represented another regional metamorphism in central NCC related to a collision process between the Eastern Block and Western Block.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"427 ","pages":"Article 107866"},"PeriodicalIF":3.2,"publicationDate":"2025-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144481647","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":"Revealing the early geological history of the Istanbul Zone (Far-East Avalonia) through zircon U-Pb-Hf isotopic data","authors":"Sinan Yılmazer ,&nbsp;Gültekin Topuz ,&nbsp;Marcel Guillong ,&nbsp;Aral I. Okay ,&nbsp;İnal Demirkaya ,&nbsp;Fulya Uzun","doi":"10.1016/j.precamres.2025.107855","DOIUrl":"10.1016/j.precamres.2025.107855","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The Istanbul Zone, located in the far-eastern part of Avalonia, is built over a composite late Neoproterozoic basement consisting of an oceanic arc and a continental domain. This basement is unconformably overlain by uppermost Cambrian to Middle Ordovician clastic sedimentary rocks. New U-Pb-Hf isotopic analyses of zircons extracted from amphibolite-facies continental metamorphic rocks and the unconformably overlying clastic rocks on the oceanic arc elucidate the earliest geological history and refine the timeline for the collision between the oceanic arc and the continent. The continental metamorphic rocks are subdivided into two distinct amphibolite-facies domains: (i) an upper amphibolite-facies domain with peak metamorphism at 568 ± 10 Ma (2σ), and (ii) a lower amphibolite-facies domain with peak metamorphism at 591 ± 6 Ma (2σ). The zircon grains in the amphibolite-facies metaclastic rocks display mainly early Neoproterozoic to Paleoproterozoic ages (0.9–2.1 Ga) with predominantly positive initial εHf values, apart from late Neoproterozoic metamorphic overgrowths. Their protoliths were likely deposited in an intracontinental rift setting during the Tonian. In contrast, the uppermost Cambrian to lowermost Ordovician sandstones reveal detrital zircon age distributions with major peaks at 601–608 Ma and minor peaks at 701–710 Ma and 1500–1501 Ma. The late Neoproterozoic zircons predominantly demonstrate negative initial εHf values (∼78 %), indicating significant involvement of crustal material in the mantle-derived magmas. Thus, the provenance of the detritus for the uppermost Cambrian to lowermost Ordovician sandstones on the oceanic arc is mainly a neighboring late Neoproterozoic continental magmatic arc with negligible input from the Meso- and Paleoproterozoic basement. A comparative analysis of the detrital zircon data with previously published data from other far-eastern Avalonian terranes reveals notable similarities. These include (i) the occurrence of metaclastic rocks with Tonian maximum deposition ages, (ii) major zircon age peaks at 589–608 Ma and minor peaks at 701–738 Ma in upper Ediacaran and uppermost Cambrian–Ordovician clastic rocks, and (iii) the occurrence of 575–615 Ma and 695–715 Ma igneous rocks that correspond to the detrital zircon age peaks in the uppermost Cambrian and Middle Ordovician clastic rocks of the Istanbul Zone, although such rocks have not yet been documented. Thus, the far-eastern Avalonian terranes were part of a unified Neoproterozoic crustal domain and were likely never separated by a large ocean. Integration of these data with published detrital zircon U–Pb ages from upper Neoproterozoic to Cambrian clastic successions in Baltica supports a provenance linkage between far-eastern Avalonian terranes and Baltica, indicating that the Istanbul Zone was accreted to Baltica during the late Neoproterozoic to early Cambrian. Subsequent post-collisional uplift and erosion likely removed the upper crustal","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"427 ","pages":"Article 107855"},"PeriodicalIF":3.2,"publicationDate":"2025-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144330972","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":"Fragments of ancient continental lithospheric mantle in the Mogok metamorphic Belt, Northern Myanmar: Re–Os isotope and platinum group element constraints","authors":"Qing-Hua Zhang ,&nbsp;Bin Su ,&nbsp;Yi Chen ,&nbsp;Victoria Pease ,&nbsp;Tou-Ping Peng ,&nbsp;Zhu-Yin Chu ,&nbsp;Yi-Bing Li ,&nbsp;Kai-Hui Shi ,&nbsp;Si Chen","doi":"10.1016/j.precamres.2025.107865","DOIUrl":"10.1016/j.precamres.2025.107865","url":null,"abstract":"<div><div>Myanmar hosts three north–south trending ophiolite belts, widely interpreted as remnants of the Tethyan Ocean. The Mogok peridotites, situated on the southern margin of Myanmar’s Eastern Ophiolite Belt, have sparked debate regarding their oceanic origin due to their atypical ophiolitic characteristics. In this study, we present Re–Os isotopic and platinum-group element data for nineteen spinel harzburgite samples from the Mogok ultramafic body, in conjunction with recently reported whole-rock major element compositions, to constrain their origin and tectonic setting. The Mogok peridotites have subchondritic ¹⁸⁷Os/¹⁸⁸Os ratios (0.11764–0.12437), with the lowest value yielding a Re-depletion model age of 1.8 Ga. This age estimate suggests their derivation from the Paleoproterozoic or more ancient lithospheric mantle. Moreover, the Mogok peridotites exhibit enrichment in iridium-group platinum group elements (Os, Ir, and Ru) and depletion in palladium-group platinum group elements (Pt and Pd). This geochemical signature closely resembles that of cratonic peridotites, indicating substantial melt extraction during their formation, consistent with their highly refractory bulk major element compositions. These results support a subcontinental lithospheric mantle origin for the Mogok peridotites, rather than previous interpretations invoking Tethys-related crustal cumulates or ophiolitic and sub-arc mantle sources. This implies limited north–south extension of Myanmar’s Eastern Ophiolite Belt, potentially terminating north of the Mogok area. These ancient Mogok peridotites were most likely uplifted from the lithospheric mantle beneath the Sibumasu terrane during the Eocene–Oligocene lithospheric extension following the West Myanmar Block–Sibumasu collision. Our study reveals ancient Gondwana-derived mantle fragments preserved within Southeast Asia’s young collisional belts, a consequence of Tethyan continental rift–drift–collision. This advances our understanding of the region’s tectonic evolution and lithospheric architecture.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"427 ","pages":"Article 107865"},"PeriodicalIF":3.2,"publicationDate":"2025-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144330963","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":"Grenvillian S-type granites in the North Qaidam orogenic belt, NW China: Implications for the geodynamic evolution of the Rodinia supercontinent","authors":"Haitao Ma,&nbsp;Pengjie Cai,&nbsp;Dongyang Lian,&nbsp;Jingsui Yang","doi":"10.1016/j.precamres.2025.107867","DOIUrl":"10.1016/j.precamres.2025.107867","url":null,"abstract":"<div><div>Recognizing tectonic positions and affinity of Precambrian micro-blocks within the Phanerozoic orogenic belts is the key to revealing global paleogeography and the evolution of supercontinents in the early Earth. The Qaidam Block, proposed as a Precambrian continental fragment surrounded by several Paleozoic orogenic belts, has been implicated in the assembly and breakup of the Rodinia supercontinent during the Mesoproterozoic to Neoproterozoic. However, the detailed tectonic position of the Qaidam Block within the Rodinia supercontinent remains poorly constrained. This study presents the integrated research of geochronology, geochemistry, and zircon Lu-Hf isotopes, as well as thermodynamic modeling on the Yuka Grenvillian granite gneiss in the North Qaidam orogenic belt. The protoliths of the Yuka granite gneiss formed at 905–908 Ma. The Yuka granite gneisses are characterized by the enrichment of aluminum with the existence of Al-enriched minerals (e.g., garnet, muscovite, and biotite) and a high aluminum saturation index (1.03–1.20), which belong to S-type granites. Zircon Lu-Hf isotopes display heterogeneous εHf(t) values (−9.7 to + 1.6) and Paleoproterozoic-Mesoproterozoic model ages (2319–1651 Ma), complemented by xenocrystic zircons spanning the Archean-Neoproterozoic (2558–937 Ma). These features collectively suggest they are derived from the partial melting of Neoproterozoic Zr-enriched <em>meta</em>-sedimentary rocks that consist of Archean-Neoproterozoic detritus. Phase equilibrium diagram and trace element modeling further demonstrate that the Yuka 905–908 Ma granite gneisses could result from various degrees of hydrous partial melting (F = 0.12–0.60) of metasediments during 690–820 ℃. Combining with the late Mesoproterozoic to Neoproterozoic magmatic and metamorphic records around the Qaidam Block, we argue that the Qaidam Block experienced Grenvillian-age (1.10–0.85 Ga) subduction-collision followed by 0.85–0.60 Ga anorogenic and continental rifting events. Comprehensive comparisons of the Qaidam Block with other major cratons and continents in the Rodinia supercontinent show that the Qaidam Block may be situated at the core part of southwest Australia, India, and East Antarctica, with no direct affinity with the North China, Tarim, and South China cratons.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"427 ","pages":"Article 107867"},"PeriodicalIF":3.2,"publicationDate":"2025-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144330971","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}