Precambrian Research最新文献

{"title":"Early Paleoproterozoic Daqingshan bimodal igneous complex in the Yinshan Block of NCC: Insights into post-collisional magmatism of a Neoarchean orogen","authors":"Shabbir Jawad ,&nbsp;Shuguang Song ,&nbsp;Yuanyuan Liu ,&nbsp;Yanguang Li ,&nbsp;Chao Wang ,&nbsp;Mark B. Allen ,&nbsp;Chunjing Wei","doi":"10.1016/j.precamres.2026.108034","DOIUrl":"10.1016/j.precamres.2026.108034","url":null,"abstract":"<div><div>Early Paleoproterozoic magmatic rocks provide crucial insights into the transition from Neoarchean cratonization to Paleoproterozoic tectonics. Nonetheless, it remains unclear whether the magmatism during this period represents a continuation of Neoarchean orogenesis, cratonization, or the onset of a new global tectonic regime. This study provides detailed field observations, zircon U–Pb geochronology, whole-rock geochemistry, Sr-Nd, and Hf isotope analysis of an igneous complex in the Daqingshan region, Yinshan Block, North China Craton. Geochemical analysis shows a bimodal trend with negligible intermediate compositions. Zircon U-Pb analyses give Paleoproterozoic ages from 2456 Ma to 2355 Ma. The felsic rocks have high Na₂O + K₂O and Fe# (Fe/(Fe + Mg) &gt; 0.7), low MgO, Ni, and Cr, and enriched in significant large ion lithophile elements (LILE), showing a variation trend from I-type to A-type granitic compositions. They also show a large variation of Sr/Y ratios (4.38‒976). Their positive Nd (+0.8 ‒ +7.3) and zircon εHf(t) values (+10.4 – +0.08) indicate a juvenile mafic crustal source with minimal mafic magma input. The mafic rocks can be categorized into high-Ti and low-Ti groups. The high-Ti group are OIB-like, whereas the low-Ti group resembles island-arc tholeiites (IAT). Their whole-rock Nd isotopic compositions (+0.1 ‒ +1.9) suggest variable mantle sources from asthenosphere to lithosphere. The Paleoproterozoic Daqingshan bimodal igneous complex was generated through the partial melting of juvenile mafic crust and lithospheric/asthenospheric mantle sources, respectively. The age pattern of the Yinshan Block shows an individual orogenic event in the Archean-Proterozoic Transition, from 2.7 Ga to 2.35 Ga without any time interval. We suggest that this bimodal complex was formed in a post-collisional setting, in the later period of a Neoarchean orogenic cycle. They reveal an extensional process of orogen collapse from thermal erosion to lithosphere delamination.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"435 ","pages":"Article 108034"},"PeriodicalIF":3.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174504","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A ∼1.6 Ga accretionary event in the polymetamorphic Lesser Himalaya, India: Insights into late-stage assembly of the Columbia supercontinent","authors":"Mallickarjun Joshi ,&nbsp;Biraja P. Das ,&nbsp;Shubham Patel ,&nbsp;Daniel Pastor-Galán ,&nbsp;Naresh C. Pant ,&nbsp;A. Krishnakanta Singh ,&nbsp;Govind Oinam ,&nbsp;Alok Kumar ,&nbsp;Ankit Kumar","doi":"10.1016/j.precamres.2026.108038","DOIUrl":"10.1016/j.precamres.2026.108038","url":null,"abstract":"<div><div>A series of collisions among most of the continental fragments between 2.1 Ga and 1.8 Ga culminated in the assembly of the Columbia supercontinent. Vestiges of reworked Northern Indian Continental Margin, involved in the Columbia supercontinent assembly, are preserved and known as the ‘Paleoproterozoic high-grade metapelitic gneisses in the Askot Klippe’ of NW Lesser Himalaya. We report new whole-rock geochemistry, inverse and forward geothermobarometric modeling, isochemical phase diagram modeling, and U–Pb zircon dating of metapelitic schists and gneisses to decode the multiple metamorphic histories in Lesser Himalayan fold-thrust. We identify two metamorphic events that mark the Columbia Supercontinent assembly’s accretion phases: an earlier ca. 1.85 Ga age related to the first metamorphic episode and a second age of ca. 1.62 Ga associated with the youngest reported collisional event related to subduction followed by accretion of crust and attendant crustal anatexis. The earlier event reached upper green-schist facies metamorphism during which garnet cores crystallized, whereas the second event indicates amphibolite-granulite peak metamorphic conditions. Our results show that the amalgamation of Columbia persisted until at least ca. 1.62 Ga in the northwestern Lesser Himalaya, indicating tectonic continuity between the northern Indian continental margin, the Aravalli–Delhi Mobile Belt, and the Eastern Cathaysia Block—key elements in the final Paleoproterozoic assembly of the Columbia supercontinent.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"435 ","pages":"Article 108038"},"PeriodicalIF":3.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174430","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":"Synsedimentary mineralization in the Paleoproterozoic McArthur River (HYC) Zn-Pb-Ag deposit, McArthur Basin, Australia","authors":"Malcolm W. Wallace ,&nbsp;Christopher P. Reed ,&nbsp;Ashleigh v.S. Hood ,&nbsp;Alexandra V. Turchyn ,&nbsp;Nicola Cawood ,&nbsp;Maxwell A. Lechte","doi":"10.1016/j.precamres.2026.108031","DOIUrl":"10.1016/j.precamres.2026.108031","url":null,"abstract":"<div><div>The McArthur River (HYC) Zn-Pb-Ag deposit of the McArthur Basin, Northern Australia is a superbly preserved example of stratiform shale-hosted mineralization. Despite extensive research on the deposit, the question of whether the sulphide minerals are synsedimentary or epigenetic remains unresolved. Here, we examine sedimentological, textural and geochemical features of the deposit to constrain the timing and environment of sulphide mineral precipitation.</div><div>Results indicate that most of the base metal sulphide minerals at McArthur River are of synsedimentary origin and were precipitated at or just below (within millimetres of) the sediment–water interface. Common sedimentological features of the ore lenses include small-scale erosion surfaces truncating sphalerite micronodules, sphalerite hardgrounds and crusts, and reworked clasts of sphalerite. All of these features indicate synsedimentary precipitation of base metal sulphide minerals. Several paleoredox proxies (including Mo, U, Cu, V, pyrite framboid size) for the host HYC Pyritic Shale Member suggest deposition occurred under a dominantly oxic-dysoxic water column, rather than in a euxinic/anoxic setting as has previously been assumed.</div><div>A sulphide mineral precipitation mechanism reminiscent of some modern marine settings is suggested for HYC metal sulphide precipitation. Sulphate reduction below the sediment–water interface, driven by a supply of organic matter, led to a buildup of H₂S in the sediment pore waters. This H₂S acted as a trap for chalcophile metals (Zn, Pb, Cu) diffusing downwards from the water column, leading to metal sulphide mineral precipitation in the near-surface sediments. This precipitation mechanism may be globally important in formation of stratiform ore deposits of this type.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"435 ","pages":"Article 108031"},"PeriodicalIF":3.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174434","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":"Neoproterozoic dolomitization, ocean redox evolution and mineralization in the Aozigang Zn deposit, Yangtze Block, South China","authors":"Xing-Yu Bai ,&nbsp;Suo-Fei Xiong ,&nbsp;Shao-Yong Jiang ,&nbsp;Ying Ma ,&nbsp;Yue Wu ,&nbsp;Guo-Qi Liu ,&nbsp;Xiao-Hua Zeng","doi":"10.1016/j.precamres.2026.108018","DOIUrl":"10.1016/j.precamres.2026.108018","url":null,"abstract":"<div><div>The origin and evolution of dolomitization in carbonate-hosted Zn-(Pb) deposits are essential for understanding ore-forming processes and reconstructing ancient marine environments. However, establishing a temporal link between dolomitization and mineralization in these deposits remains challenging due to the scarcity of direct geochronological constraints. This limitation hinders a comprehensive understanding of metallogenic processes and paleoenvironmental reconstructions. To address this issue, we present an integrated study of the Aozigang Zn deposit in Hubei Province of South China.</div><div>We reveal distinct generations of dolomite, which include sedimentary breccia dolomite (SBD), fascicular fast dolomite (FFD), fascicular slow dolomite (FSD), bladed dolomite (BD), radial slow dolomite (RSD), and medium-crystalline to coarse-crystalline dolomite (MD). The dull-red CL color and fabric features of the FSD suggest that dolomitization occurred under near-surface to shallow-burial, anoxic marine conditions. Uranium-Pb dating of FSD yields an age of 546.9 ± 7.4 Ma (MSWD = 2.8, n = 74), indicating that dolomitization took place during the Neoproterozoic. By combining the <em>in situ</em> carbon isotope composition of sedimentary dolomite, we provide direct chronological evidence for the delayed oxygenation of the Neoproterozoic ocean. The elevated Mn/Sr ratios and Mn enrichment observed in later MD are consistent with hydrothermal recrystallization under reducing conditions. The clear rim and cloudy core of MD serve as direct petrography evidence of the recrystallization from early dolomite. Meanwhile, the δ¹³C and δ¹⁸O values of hydrothermal calcite (peak at +0.27‰ to +1.43‰ and −11.81‰ to −7.40‰, respectively) reflect the influence of relatively high-temperature fluids and lower oxygen fugacity. The Pb isotopes of sphalerite indicate a mixed metal source that involves contributions from both the upper crust and basement. This study integrates geochronological and geochemical methods to provide direct dating evidence for Precambrian dolomitization, which is associated with the global oxygenation event known as the Neoproterozoic Oxygenation Event (NOE). The results offer a new perspective for investigating carbonate-hosted ore deposits on a global scale.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"435 ","pages":"Article 108018"},"PeriodicalIF":3.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080777","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 of the Acraman impact ejecta layer in the adelaide superbasin and Implications on clay-mineral provenance from the Rb–Sr systematics of middle Ediacaran shales","authors":"Alan S. Collins ,&nbsp;Morgan L. Blades ,&nbsp;Darwinaji Subarkah ,&nbsp;Holly Cooke ,&nbsp;Lesley Edwards ,&nbsp;Chelsea Forbister ,&nbsp;Jake Jolly ,&nbsp;Jarred C. Lloyd ,&nbsp;Sarah E. Gilbert ,&nbsp;Stefan Löhr ,&nbsp;Juraj Farkaš ,&nbsp;Victor Gostin","doi":"10.1016/j.precamres.2026.108015","DOIUrl":"10.1016/j.precamres.2026.108015","url":null,"abstract":"<div><div>The Acraman bolide hit the Gawler Craton of South Australia in the middle Ediacaran. Debris from this impact punctuates the Ediacaran sequences of the Adelaide Superbasin and the eastern Officer Basin. Here we date an argillaceous Acraman impactite layer sampled from Arkaba Creek, in the Bunyeroo Formation of the Adelaide Superbasin at 585 ± 15 Ma (MSWD = 1.8, 2σ error) using the <em>in-situ</em> Rb–Sr ICP-MS/MS technique that we interpret to date the impact event. The analyses have a radiogenic ⁸⁷Sr/⁸⁶Sr initial ratio of 0.7210 ± 0.0028 and elevated light rare earth element values.</div><div>Shales from both above and below the impact horizon yielded ages significantly pre-dating deposition and are interpreted to reflect detrital input into the Bunyeroo Formation, which is consistent with previous petrographic studies. Intriguingly, all 10 shales analysed yielded Rb–Sr ages within error of each other, with a Tonian weighted mean age of 778 ± 17 Ma (MSWD = 0.83). This is interpreted to reflect a very similar clay mineral age provenance for these shales despite being found in samples over 600 km apart. A similar mix of detrital mineral ages cannot be discounted. However, considering the spatial distribution, an alternative interpretation that the age similarity reflects Tonian pedogenic clay formation on the Gawler Craton, is thought more likely.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"435 ","pages":"Article 108015"},"PeriodicalIF":3.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146015904","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":"Source and petrogenesis of Paleoproterozoic Meta-Mafic rocks in the South-Eastern North China Craton: Implications for the tectonic transition from extension to collision in the Jiao-Liao-Ji belt","authors":"Yayun Liang ,&nbsp;Tong Qu ,&nbsp;Lei Shu ,&nbsp;Jiayi Shen ,&nbsp;Haiyi Wang ,&nbsp;Linyi Li ,&nbsp;Hao Yan ,&nbsp;Jun Deng","doi":"10.1016/j.precamres.2026.108033","DOIUrl":"10.1016/j.precamres.2026.108033","url":null,"abstract":"<div><div>The tectonic evolution of the Paleoproterozoic Jiao-Liao-Ji belt (JLJB) remains highly controversial, specifically whether its 1.95–1.80 Ga metamorphism records intracontinental rifting or arc-continent collision. To resolve this debate, we present the first integrated study of zircon U-Pb geochronology, Hf isotopes, and whole-rock geochemistry on <em>meta</em>-mafic dykes from the Jiaodong Terrane, southeastern North China Craton. New LA-ICP-MS zircon U-Pb data reveal two distinct age groups: inherited zircons (ca. 2.6–2.7 Ga) with magmatic textures, sourced from Neoarchean basement; and metamorphic zircons (1,904 ± 24 Ma and 1,894 ± 18 Ma) recording orogenic reworking. Geochemical signatures (E-MORB affinities, LREE enrichment, low Nb/La = 0.3–0.4, and variable εHf(t) = –9.4 to + 9.3) indicate derivation from a metasomatized subcontinental lithospheric mantle (SCLM). Critically, the dykes’ protoliths formed in an extensional setting prior to 1.9 Ga, as evidenced by: pre-metamorphic gabbroic textures preserved in relict cores; negative Nb-Ta anomalies implicating subduction-modified SCLM sources; and low Mg# (40–55) suggesting crustal assimilation during magma ascent. We propose that the 1.9 Ga metamorphic event marks the closure of this extensional basin, triggering collisional orogeny. This dual-record mechanism—where dyke emplacement age (&gt;1.9 Ga) constrains pre-collisional extension, while the metamorphic age (1.9 Ga) dates collision onset—establishes a new tectono-chronological framework. Our results reconcile conflicting models for the JLJB by demonstrating a complete extension-to-collision transition (2.2–1.9 Ga), advancing the understanding of cratonic stabilization during Columbia assembly.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"435 ","pages":"Article 108033"},"PeriodicalIF":3.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174457","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":"Columbia supercontinent remnants in the Tuareg Shield (Iforas, Mali)","authors":"Delphine Bosch ,&nbsp;Olivier Bruguier ,&nbsp;Vincent Monchal ,&nbsp;Heloise Pinon","doi":"10.1016/j.precamres.2026.108019","DOIUrl":"10.1016/j.precamres.2026.108019","url":null,"abstract":"<div><div>The Iforas Granulitic Unit (Tuareg Shield), east of the West African Craton, is a key place to help reconstructing the Columbia supercontinent evolution. In this area, the emplacement of magmatic protoliths is constrained at c. 2.05–2.06 Ga and the production of the magmas involved recycling of a Paleoproterozoic to Archean crustal component (up to 3.0 Ga). For the first time, this study emphasizes two distinct Paleoproterozoic granulitic events. The first one occurs at ca. 2.0 Ga and was followed by a second event of very-high temperature (up to 920°C) at ca. 1.89 Ga. Rocks from the Iforas Granulitic Unit subsequently remained at high temperature (≥500°C) for a protracted period of <em>c.</em> 150 Myrs and record multiple phases of accessory mineral growth, dissolution and recrystallisation. This is illustrated by U-Pb monazite ages, peaking at 1780–1760 Ma, reflecting fluid driven replacement reactions as documented by apatite / allanite coronas around monazite. Cooling of the granulites, down to <em>c.</em> 500°C, occurred in the range 1720–1700 Ma (apatite and rutile ages). The chronology of the magmatic/metamorphic events is consistent with a collisional setting involving a micro-continental block consisting of the Iforas / In Ouzzal granulitic units sandwiched between the West African Craton and an eastern landmass which may be the Saharan metacraton. This study has major consequences for global reconstructions of the Columbia supercontinent as it demonstrates that, at <em>c.</em> 1.8 Ga, this microcontinent fits as a continuation of the Khondalite Belt or Trans North China Belt of the North China Craton.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"435 ","pages":"Article 108019"},"PeriodicalIF":3.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080775","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":"Missing crustal sources to Archean clastic sediments revealed by new U-Pb, trace element, Hf and O isotopic data from detrital zircons of the Barberton Greenstone Belt (South Africa)","authors":"Combaz Jean-Baptiste ,&nbsp;Laurent Oscar ,&nbsp;Stevens Gary ,&nbsp;Drabon Nadja ,&nbsp;Glynn Sarah ,&nbsp;Couffignal Frédéric","doi":"10.1016/j.precamres.2026.108016","DOIUrl":"10.1016/j.precamres.2026.108016","url":null,"abstract":"<div><div>The formation of the Earth’s earliest silicic crust has been largely addressed through the study of the dominant Archean felsic lithology, i.e. tonalite – trondhjemite – granodiorite (TTG) rocks. However, Archean terranes may have been affected by significant preservation biases, which have been overlooked so far. To address this issue, we have conducted a comprehensive study of U-Pb ages, Hf and O isotopic and trace element compositions of detrital zircons deposited over the entire sequence of clastic sediments of the Barberton Greenstone Belt (South Africa). Our study first reveals the importance of local sourcing of sedimentary successions at all stratigraphic levels, which highlights the importance of investigating supracrustal zircons from a large sample set, representative of the lithological diversity and stratigraphy in a given area. Second, our results point to significant biases in the preservation of the Paleoarchean crustal record. First, zircons deposited in both the ca. 3.43 Ga Hooggenoeg Formation and the ca. 3.25 Ga Schapenburg Schist Belt show age populations and/or trace element compositions that do not have plutonic equivalents in the plausible source terranes and suggest erosion of felsic rocks different from the exposed TTGs. Second, compiling our results with datasets from previous work, 40% of all detrital zircons of the ca. 3.22 Ga Moodies Group, while having similar age distribution as that of igneous zircon from regionally exposed TTGs/gneisses, show distinct εHf_(t) values (dominantly sub-chondritic) and trace element contents from those of igneous zircons (notably showing dominantly supra-chondritic εHf_(t)). This also applies to ca. 3.53-3.45 Ga, negative-εHf_(t) zircons from two samples of felsic schists of the Theespruit Formation. We therefore interpret these non-radiogenic zircons to have been sourced from an unpreserved, isotopically evolved and non-TTG magma source, most likely similar to granitic/rhyolitic clasts of the Moodies Basal Conglomerate and the felsic volcanic sequences of the Theespruit Formation. The high proportion of zircons pointing to non-TTG sources and their presence at all stratigraphic levels of the Barberton Greenstone Belt suggest that these zircons are the relics of hitherto much more voluminous components of the Paleoarchean felsic crust than presently exposed. This result calls for a reassessment of the lithological diversity of the Earth’s first silicic crust.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"435 ","pages":"Article 108016"},"PeriodicalIF":3.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174431","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 Ediacaran sea-level fluctuations and microbialite records of the Yangtze Platform: Implications for astronomical forcing","authors":"Qiuding Du ,&nbsp;Jian Wang ,&nbsp;Gang Zhou ,&nbsp;Anjiang Shen ,&nbsp;Wenqiang Tang ,&nbsp;Xiugen Fu ,&nbsp;Yuan He ,&nbsp;Hengye Wei ,&nbsp;Haolong Zhang","doi":"10.1016/j.precamres.2026.108029","DOIUrl":"10.1016/j.precamres.2026.108029","url":null,"abstract":"<div><div>The late Ediacaran stands as a pivotal interval in Earth’s history, marked by the extensive development of microbial carbonate deposits that are crucial for documenting the biotic evolution and environmental changes of this period, as well as serving as significant hydrocarbon reservoirs. Accordingly, this study investigates the microbial carbonates of the late Ediacaran Dengying Formation on the Yangtze Platform, South China, to unravel the underlying mechanisms linking microbialite development, sea-level change, and astronomical forcing. Through a multi-proxy approach including petrography, high-resolution gamma-ray logging, Fischer plot analysis, and spectral methods (Multi-Taper, correlation coefficients), this study demonstrates that high-quality reservoirs occur predominantly within mound-shoal complexes, where microbialite abundance correlates with periods of sea-level rise. The ecological recovery following the extinction of the Ediacara-type biota created favorable niches for microbialite proliferation. Their widespread deposition occurred mainly during periods of sea-level rise, which can be attributed to both low sedimentation rates and enhanced nutrient supply. Despite its relatively short duration (&lt;3 Myr), the studied succession contains well-preserved Milankovitch signals that point to a multi-component astronomical influence. Specifically, a clear causal relationship exists between third-order sea-level changes and ∼2.2 Myr eccentricity modulation cycles, while higher-frequency, meter-scale fluctuations are paced by precession modulation cycles. Alongside the primary control of astronomical forcings, tectonic activity played a secondary role, potentially driving the prolonged lowstand associated with the final amalgamation of Gondwana. Thus, this study highlights that late Ediacaran sea-level evolution was governed by the superposition of orbital and tectonic mechanisms, providing new insights into the driving forces of this period.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"435 ","pages":"Article 108029"},"PeriodicalIF":3.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174436","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":"Embryonic Proto-Tethys Ocean: Evidence from the early Ediacaran Kuyake ophiolite mélange along the Altyn Tagh in NW China","authors":"Hong-Ran Wang ,&nbsp;Chuan-Lin Zhang ,&nbsp;Hua-Dong Ma ,&nbsp;Yan Jing ,&nbsp;Masumeh Sargazi ,&nbsp;Zhi-Hao Song","doi":"10.1016/j.precamres.2026.108036","DOIUrl":"10.1016/j.precamres.2026.108036","url":null,"abstract":"<div><div>The northern part of the Tethyan tectonic domain in China, including the west Kunlun, Altyn, Qilian, and northern Qinling regions, preserves an important record of late Precambrian–early Palaeozoic tectonic processes associated with the breakup of Rodinia and early evolution of the Proto-Tethys Ocean. However, it remains unclear when, where, and why the Proto-Tethys Ocean opened. In this study, we identified an early Ediacaran ophiolitic mélange (i.e., the Kuyake ophiolite) along the southern margin of the Altyn Tagh, which provides key evidence for the early evolution of the Proto-Tethys Ocean. The Kuyake ophiolitic mélange consists of serpentinised residual mantle peridotites, cumulate plutonic rocks, basalts, and cherts. Zircon U–Pb dating of the gabbros yielded crystallisation ages of 628 ± 4 and 622 ± 5 Ma, which represent the oldest dated Proto-Tethyan oceanic lithosphere. The cumulates have flat rare earth element patterns and normal-type mid-ocean ridge basalt (N-MORB)-like incompatible trace element characteristics. The basalts can be divided into two groups. Group 1 has typical N-MORB-like geochemical features, while group 2 has enriched-type MORB-like rare earth and incompatible element compositions. The major and trace elements, and whole-rock Nd (ε_Nd[<em>t</em>] = 0.4–6.7) and zircon Hf (ε_Hf[<em>t</em>] = –8.5 to + 6.1) isotopic compositions show that the cumulates and basalts were derived mainly from depleted asthenospheric mantle, but underwent variable crustal assimilation and fractional crystallization. This is also consistent with the geochemical features of the chert. Based on the rock association, geochemistry, and regional geology, we propose that the early Ediacaran Kuyake ophiolitic mélange represents embryonic oceanic crust that formed during the early stages of opening of the Proto-Tethys Ocean in East Asia. This ophiolitic mélange provides key constraints on the relationship between the breakup of the Rodinia and assembly of Gondwana.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"435 ","pages":"Article 108036"},"PeriodicalIF":3.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174433","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}