Precambrian Research最新文献

{"title":"Corrigendum to “Crustal evolution and architecture of the Wawa Subprovince, Superior Province: Insights from zircon U-Pb-Hf-O isotopes and geochemistry” [Precambrian Res. 418 (2025) 107705]","authors":"K.G. Nymoen , D.R. Mole , P.C. Thurston , D.K. Tinkham , J.H. Marsh , R.A. Stern","doi":"10.1016/j.precamres.2025.107725","DOIUrl":"10.1016/j.precamres.2025.107725","url":null,"abstract":"","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"419 ","pages":"Article 107725"},"PeriodicalIF":3.2,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143479299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pulsed oxygenation events at ∼ 1.44–1.43 Ga: Evidence from the Tieling Formation in the North China Platform","authors":"Yang Yu ,&nbsp;Yuelong Chen ,&nbsp;Dapeng Li ,&nbsp;Baoshan Xia","doi":"10.1016/j.precamres.2025.107723","DOIUrl":"10.1016/j.precamres.2025.107723","url":null,"abstract":"<div><div>The unique accumulation of oxygen (O₂) in Earth’s oceans and atmosphere distinguishes it from other rocky planets. The oxygenation of the Mesoproterozoic ocean–atmosphere system was a protracted process, yet it may have included transient oxygenation events, particularly before ∼ 1.4 billion years ago. Despite ongoing research, the detailed nature of redox conditions and the origin of a potential oxygenation event around 1.44–1.43 Ga remain poorly understood. Here, we present a suite of geochemical proxies, including iodine-to-calcium-magnesium [I/(Ca + Mg)], rare earth elements (REE) plus Y (REY), carbonate-associated sulfate sulfur isotopes (δ³⁴S_CAS), Rb/Al, and P/Al ratios for the carbonate rocks of the Tieling Formation (ca. 1.44–1.43 Ga) from two well-preserved sections of the North China Platform. The lower Tieling Formation (Daizhuangzi Member) exhibits middle REE-enriched patterns and elevated I/(Ca + Mg) values (up to 1.32 µmol/mol), suggesting potentially oxic or suboxic seawater conditions. The upper Tieling Formation (Laohuding Member) shows a pronounced increase in I/(Ca + Mg) at the basal interval, followed by a further marked rise in the middle to upper portion of this member. The rising I/(Ca + Mg) ratios, coupled with negative shifts in Ce anomalies, imply at least two pulses of oceanic oxygenation during deposition. Notably, the peak in I/(Ca + Mg) ratios in the middle-upper Laohuding Member corresponds with previously reported positive Cr isotope fractionation, indicating an oxygenation event that extended to the atmosphere. Similar oxygenation signals have also been recognized in the time-equivalent Fengjiawan Formation of southern North China and the Kaltasy Formation of the Russia, suggesting a multi-basin oxygenation process at ∼ 1.44–1.43 Ga. Additionally, elevated P/Al and Rb/Al ratios beneath the Laohuding Member point to intensified terrestrial weathering and nutrient delivery to the ocean that may have accelerated the pyrite burial and contributed to the oxygenated events during this period.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"419 ","pages":"Article 107723"},"PeriodicalIF":3.2,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143377965","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":"Carbon cycling, redox condition and solute fluxes in the middle Paleoproterozoic Ocean: Constraints from elemental and C-O, Nd-Sr isotope geochemistry of stromatolitic carbonates from Vempalle Formation, Cuddapah Basin","authors":"M. Ashok,&nbsp;Nurul Absar","doi":"10.1016/j.precamres.2025.107724","DOIUrl":"10.1016/j.precamres.2025.107724","url":null,"abstract":"<div><div>The early Orosirian Period (2.05–1.9 Ga) was marked by unprecedented changes in carbon cycling and the redox state of the global ocean, and marine carbonates are a useful archive to study these changes. Here, we present detailed C-O, Nd-Sr isotopic, and trace element chemostratigraphy of a well-preserved stromatolitic carbonate sequence (∼1.2 Km thick) from ∼ 2.0–1.9 Ga Vempalle Formation (VF), Cuddapah basin, India; and aim to elucidate redox conditions, carbon cycling, and solute sources to the post-Great Oxidation Event (GOE) ocean. The basal VF (0–200 m) records a prominent negative δ¹³C excursion of magnitude ∼ 3 ‰, which is followed by an invariant δ¹³C (0.46–1.35 ‰) in the rest of the upper section. Oxidative remineralisation of organic matter in a relatively low dissolved inorganic carbon (DIC) oceanic reservoir explains the negative δ¹³C excursion, whereas muted δ¹³C variations in the upper part would suggest environmental stability under high <em>_p</em>CO₂. The ¹³Δ (δ¹³C_carbonate- δ¹³C_org) values between 24.9 and 28.8 (avg. 27.4) show photoautotrophic carbon fixation by primary producers. The transition from relatively well-oxygenated to less-oxygenated surface conditions and contraction of oceanic redox-sensitive elements (RSE) reservoir is indicated by a marked decline of U and V abundances after an initial high concentration recorded in the basal VF (0–80 m). The Light Rare Earth Element (LREE) or Middle Rare Earth Element (MREE) enriched patterns, very high Fe and Mn concentrations in the upper VFs suggest a predominant anoxic-ferruginous ocean and active redox cycling of REE below the Mn- or Fe-redoxcline. These data, combined with the shallow depositional bathymetry, imply a very shallow redoxcline. High radiogenic εNd_{2 Ga} values in the VF compared to the average Dharwar crust indicate significant inputs of mantle-derived hydrothermal fluid to the ocean. Large-scale advection of hydrothermal fluid onto the shallow carbonate platform would indicate a tectonically active basin.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"419 ","pages":"Article 107724"},"PeriodicalIF":3.2,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143377966","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":"Metamorphic remobilization of Archean Au: Insights from the world-class Hemlo deposit, Canada","authors":"O Nadeau ,&nbsp;M.I. Leybourne ,&nbsp;A Voinot ,&nbsp;A Poirier","doi":"10.1016/j.precamres.2025.107710","DOIUrl":"10.1016/j.precamres.2025.107710","url":null,"abstract":"<div><div>Although most Archean orogenic Au deposits formed after the related metamorphic events, numerous deposits have formed prior to peak metamorphic conditions, and abundant research has focused on the remobilization of Au by metamorphic-hydrothermal fluids. At the Archean Hemlo Au deposit, Canada, most recent research agrees that Au mineralization first occurred prior to metamorphism and that Au was subsequently remobilized. Given that Li is mobile, relatively compatible in micas and clay minerals, and experiences isotopic fractionation primarily as a result of fluid-rock reactions, here, Li isotopic composition is analyzed using multiple collector ICP-MS and used to investigate Au remobilization during metamorphic-hydrothermal alteration. It is shown that bulk rock Li concentrations and isotopic compositions changed simultaneously with Au remobilization, as a result of the metamorphic recrystallization of biotite, chlorite, muscovite, and white mica. The concentration of Li increased from 2.6-58 ppm in hydrothermally-altered rocks, and δ⁷Li values decreased simultaneously, from + 10.5 to + 1.4 ‰. Interestingly, the δ⁷Li values correlate positively with Au and Li concentrations, indicating that the metamorphic-hydrothermal fluid remobilized Au as the rocks were fluxed with Li, and the biotite-chlorite-muscovite-white mica assemblages were recrystallized. In addition to bulk rock analyses, the concentration of Li-Au was measured in minerals using laser ablation ICP-MS, in order to investigate why bulk rock δ⁷Li values and Li concentrations are systematically correlated with Au concentrations. The presence of Au in K-feldspar is ascribed to primary mineralization and related K-feldspar alteration, whereas that in prograde and retrograde biotite, as well as in retrograde chlorite, muscovite, and white mica, must have resulted from the metamorphic-hydrothermal alteration and related Au remobilization. The decrease in Au counts and concentrations in minerals representing the sequence of recrystallization support bulk rock results suggesting that some Au was remobilized during metamorphism. Overall, these results highlight the strong potential of Li isotopes for Au exploration and metallogenic studies.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"419 ","pages":"Article 107710"},"PeriodicalIF":3.2,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143377058","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":"Carbonaceous macrofossils from the Ediacaran–Cambrian lower shale member of the Soltanieh formation, Northwestern Iran","authors":"Najmeh Etemad-Saeed ,&nbsp;Shuhai Xiao ,&nbsp;Steve C. Wang ,&nbsp;Kristin D. Bergmann ,&nbsp;Andrew H. Knoll","doi":"10.1016/j.precamres.2025.107722","DOIUrl":"10.1016/j.precamres.2025.107722","url":null,"abstract":"<div><div>The Ediacaran–lower Cambrian Soltanieh Formation exposed in the Soltanieh Mountains of northwestern Iran is a mixed siliciclastic-carbonate succession that hosts skeletal animals, metazoan trace fossils, and macroalgal compressions, in addition to a well-resolved C isotopic record. Here we attempt to clarify the systematic paleontology of carbonaceous compression macrofossils found at the base of the Lower Shale Member of this formation, close to the Ediacaran–Cambrian boundary, and discuss their implications for our understanding of the early evolution of complex multicellular organisms. We identified five distinct morphological groups: (1) small discoidal fossils (chuarids), (2) branching thalli (<em>Eoholynia corumbensis</em>), (3) large discoidal fossils (<em>Doulia rara</em>), (4) simple ribbon-like compressions, and (5) chuarid-like discoidal structures with an attached filament. These fossils display limited diversity but include representatives of the three groups that dominate Ediacaran–Cambrian macrophyte diversity globally. All are present at the stratigraphic level in which Cambrian animals and trace fossils first appear, providing broader biological context for understanding early animal diversification.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"419 ","pages":"Article 107722"},"PeriodicalIF":3.2,"publicationDate":"2025-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143349329","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":"Middle Paleoproterozoic tectonic evolution of the North China Craton: Constraints from the A-type granites in the Wutai area","authors":"Jingyu Wang ,&nbsp;Yujing Wang ,&nbsp;Wei Hong ,&nbsp;Caiyun Lan ,&nbsp;Jingjing Fan ,&nbsp;Xiaoping Long","doi":"10.1016/j.precamres.2025.107711","DOIUrl":"10.1016/j.precamres.2025.107711","url":null,"abstract":"<div><div>The Paleoproterozoic tectonic evolution of the Trans-North China Orogen of the North China Craton (NCC) has long been controversial. One of the key factors is the difference in the understanding of the A-type granites in the middle Paleoproterozoic. In this study, whole-rock geochemistry and Nd isotope, zircon U-Pb and Hf-O isotope, and zircon H₂O content are reported for middle Paleoproterozoic syenogranite, monzogranite, and alkali-feldspar granite in the Wutai area. LA-ICP-MS zircon dating results show that the intrusions have emplacement ages from 2117 to 2133 Ma. The 2.1<!--> <!-->Ga granites in the Wutai area exhibit elevated SiO₂ (72.20–78.01 wt%), K₂O + Na₂O (7.32–8.78 wt%) and Zr + Nb + Y + Ce (&gt; 528 ppm) concentrations, high FeOt/(FeOt + MgO) (0.78–0.89), 10000*Ga/Al (&gt; 3) and K₂O/Na₂O (1.0–1.9) ratios, low TiO₂/MgO ratios (0.4–1.4), and significant depletion of Ba, Sr, Eu, as well as high zirconium saturation temperatures (785–892°C), showing typical characteristics of aluminous A-type granites. The samples display characteristics of relatively enriched zircon Hf isotopes (εHf(t) = −5.6 to + 2.7), whole-rock Nd isotopes (εNd(t) = −2.9 to + 0.3), and old two-stage Hf model ages (2.56–3.05 Ga) similar to those of Neoarchean TTG gneisses in the same area. Furthermore, the oxygen isotope composition of zircon (δ¹⁸O = 4.7 to 7.4 ‰) are lower than those of zircons from the A-type granites derived from <em>meta</em>-sedimentary melts, indicating that the A-type granites are predominantly derived from the partial melts of Archaean TTGs. These granites contain both ilmenite and magnetite, indicating a relatively oxidizing environment. Zircon (log(fO₂) = −14.9 to − 7.8) and biotite (log(fO₂) = −13.5 to − 11) also show high oxygen fugacity. The water content of zircon is 104–842 ppm, with an average of 414 ppm, showing a relatively wet environment. These oxidised and water-rich A-type granites are likely to form in a back-arc extensional setting. Combined with the published NCC data, the Trans-North China Orogen is inferred to be an Andean-type continental arc setting in the middle Paleoproterozoic, suggesting the possibility of continuous subduction in the Paleoproterozoic.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"419 ","pages":"Article 107711"},"PeriodicalIF":3.2,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140512","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":"Crustal reworking during the transition of tectonic regime in the Paleoproterozoic Era: Constraints from geochemistry, Sm-Nd isotope and U-Pb geochronology of granitic gneisses, Dudhi Granitoid Complex, Mahakoshal belt, Central Indian Tectonic Zone (CITZ), India","authors":"Mahendra Shukla ,&nbsp;Sanjeet K. Verma ,&nbsp;Vivek P. Malviya ,&nbsp;Elson P. Oliveira ,&nbsp;Sumit Mishra ,&nbsp;Ravi K. Umrao ,&nbsp;Satya Prakash ,&nbsp;Erik Emmanuel M. Torres","doi":"10.1016/j.precamres.2024.107660","DOIUrl":"10.1016/j.precamres.2024.107660","url":null,"abstract":"<div><div>The Paleoproterozoic Dudhi Granitoid Complex is composed of numerous granitoid intrusions and gneissic components that is located in the Mahakoshal belt, which is an important supracrustal belt of the Central Indian Tectonic Zone (CITZ) and played a vital role in the crustal accretion of the Columbia supercontinent. Thus, we present new geochemical data, Sm-Nd isotope analyses, and U-Pb geochronology of the granitic gneisses from the Dudhi Granitoid Complex to understand their origin, evolution and tectonic setting. The LA-ICP-MS zircon U-Pb dating yields ages of 1707.9 ± 7.4 Ma, 1724.3 ± 8.6 Ma, 1736.8 ± 9.9 Ma, 1748.3 ± 7.9 Ma, and 1756.3 ± 10 Ma for studied granitic gneisses. These rocks are strongly metaluminous and show enrichment in high field strength elements (HFSE) and depletion in large ion lithophile elements (LILE). The trace element composition allows classifying these rocks as an A₂-type affinity in an extensional environment. They show negative values of ɛNd(t) (−5.7 to −0.4) and old Nd-model ages (T_DM: 2068–2420) support their crustal origin. Geochemical and Nd isotope data indicate that they were derived by partial melting of older granites and granitic gneisses crust i.e., Archean Bundelkhand crust and Paleoproterozoic (&gt;1.9 Ga) juvenile crustal basement of the Mahakoshal basin. Finally, their magmatism during 1.75–1.70 Ga is linked to the transition period of accretion and dispersal of the Columbia supercontinent, which is incorporated into the lithosphere of the CITZ.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"417 ","pages":"Article 107660"},"PeriodicalIF":3.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137427","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":"Spatial U-Pb age distribution in botryoidal dolomite in the terminal Ediacaran Dengying Formation, South China: Constraints on “dolomite seas” and formation process","authors":"Entao Liu ,&nbsp;Detian Yan ,&nbsp;Jian-xin Zhao ,&nbsp;Jingbin Wang ,&nbsp;Yuexing Feng ,&nbsp;Lifeng Zhong ,&nbsp;Hua Jiang ,&nbsp;Nengping Shen ,&nbsp;Junming Zhan","doi":"10.1016/j.precamres.2024.107636","DOIUrl":"10.1016/j.precamres.2024.107636","url":null,"abstract":"<div><div>Widespread fibrous dolomite cements in upper Ediacaran Dengying Formation’s botryoidal dolomite were traditionally thought to form through secondary processes, but recent studies indicate they were likely the direct products of unique “dolomite seas” conditions. To elucidate botryoidal dolomite’s formation and the unique “dolomite seas,” it’s vital to date the age variability in its dolomite cements via absolute methods. In this study, we performed the first comprehensive geochronological and geochemical (C-O-Sr-REE) analyses on a representative botryoidal dolomite hand specimen PTHB-1, which is divisible into three distinct components: microbialite matrix, fibrous marine dolomite, and crystalline dolomite. Through <em>in-situ</em> laser-ablation ICP-MS U-Pb analyses of 720 meticulously selected laser spots across the specimen, we obtained a dataset of 14 U-Pb age determinations for the various dolomite cements. Notably, ten laminae of U-enriched fibrous dolomite cements yielded ten high-precision U-Pb ages bracketing a time range between 550.1 ± 8.0 Ma and 542 ± 14 Ma (weighted mean 546.8 ± 3.2 Ma), aligning chronologically with the stratigraphic age interval (551.1–542 Ma). These findings, coupled geochemical signatures and petrographic evidence, suggest that the fibrous dolomite cements were initially direct marine precipitates, challenging previous secondary genetic interpretations. This revelation points to a short-lived “dolomite sea” existed in the terminal Ediacaran Ocean in the upper Yangtze region. Conversely, the later stages of vug-filling crystalline dolomite cements exhibit pronounced positive Eu and Y anomalies along with lower δ¹³C and δ¹⁸O, indicating hydrothermal fluid precipitation. Our results reveal at least three phases of crystalline dolomite cements at ca. 411 ± 17 Ma, 358.7 ± 6.1 Ma, and 257.2 ± 8.4 Ma, respectively, contributing significantly to the modification of reservoir properties. The insights gleaned from this research provide crucial chronological data for comprehending the formation and evolutionary history of botryoidal dolomite reservoirs, with substantial implications for hydrocarbon exploration efforts.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"417 ","pages":"Article 107636"},"PeriodicalIF":3.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137578","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":"Depositional age and environment of the Xinyu iron deposit in the Nanhua Basin, South China","authors":"Xiufang Wang ,&nbsp;Hui Ye ,&nbsp;Yuan Gao ,&nbsp;Matthew J. Brzozowski ,&nbsp;Xiang Li ,&nbsp;Ru-Xiong Lei ,&nbsp;Chang-Zhi Wu","doi":"10.1016/j.precamres.2024.107671","DOIUrl":"10.1016/j.precamres.2024.107671","url":null,"abstract":"<div><div>Deposition of Neoproterozoic iron formations (IFs) was typically associated with Cryogenian glaciations and the breakup of the Rodinia supercontinent. Neoproterozoic IFs in South China are distinct, however, as they lack evidence for glacial and volcanic influence. The correlation of these IFs with Neoproterozoic sedimentary successions and their depositional environment remain controversial. Here we present new geochronological and geochemical constraints on the depositional age and environment of the Xinyu IF, one of the largest Neoproterozoic IFs in the Nanhua Basin of South China. The Xinyu IF, intercalated with clastic rocks and not in direct contact with glaciogenic sedimentary rocks, suggests deposition in an open water environment during the Sturtian glacial period. The Xiafang Formation, which hosts the Xinyu IF, overlies the diamictite-bearing Gujia Formation and underlies the gravel-containing and manganese (Mn)-bearing of the Dashajiang Formation. The youngest three zircon grains of the Xiafang Formation give a weighted mean ²⁰⁶Pb/²³⁸U age of 694 ± 17 Ma, representing the maximum depositional age of this formation. The Xiafang Formation is, therefore, likely correlated to the Liangjiehe Member of the Fulu Formation in the western Nanhua Basin, and was likely deposited between 694 ± 17 and 691 ± 12 Ma. Shale-normalized rare earth element (REE) plus Y (REY) patterns of the Xinyu IF samples display light REE depletion (average (LREE/HREE)_SN = 0.37) relative to heavy REE, insignificant Eu anomalies (Eu* = 0.85−1.21), and no Ce anomalies (Ce* = 0.95−1.00). These geochemical characteristics suggest that the Xinyu IF was likely deposited in anoxic seawater in which Fe(II) was likely sourced from low-temperature hydrothermal fluids. Collectively, we suggest that the Xinyu IF is a Cryogenian IF deposited in open water during the Sturtian glaciation.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"417 ","pages":"Article 107671"},"PeriodicalIF":3.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137597","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":"Paleoproterozoic deep carbon cycle recorded in carbonatites","authors":"Dongyang Liu ,&nbsp;Cheng Xu ,&nbsp;Marco Brenna ,&nbsp;Xijun Liu ,&nbsp;Qiuli Li ,&nbsp;Chunwan Wei","doi":"10.1016/j.precamres.2024.107669","DOIUrl":"10.1016/j.precamres.2024.107669","url":null,"abstract":"<div><div>The deep carbon cycle regulates mantle-derived magma and atmospheric CO₂ on geological timescales. However, the timing of initial carbon subduction into the mantle remains debated. Here, we compare the geochemical characteristics and origin of Paleoproterozoic Zhuozi and Fengzhen carbonatite-syenite complexes within the Trans-North China Orogen. The Zhuozi syenitic zircons have an older age than the Fengzhen samples (1941 vs 1810 Ma) and show unusually high δ¹⁸O (11.8 to 13.8 ‰) compared to most Paleoproterozoic igneous zircons. Their associated carbonatites have sediment-like δ¹³C (−1.8 to −1.0 ‰) and δ¹⁸O (10.7 to 18.0 ‰). Both rock types at Zhuozi have high εNd_t (−1.4 to 2.8) and εHf_t (−2.0 to 5.0) values inconsistent with wall rock contamination, in contrast with the Fengzhen complex that has lower Nd-Hf isotopes. However, in-situ Pb isotopes of feldspars in Zhuozi syenites show more radiogenic compositions than the Fengzhen samples (²⁰⁷Pb/²⁰⁴Pb = 15.21–15.38 vs 14.84–14.95, ²⁰⁸Pb/²⁰⁴Pb = 35.06–35.56 vs 34.20–34.49). The Zhuozi and Fengzhen complexes may be products of Columbian supercontinent assembly. The differences of isotopic characteristics indicate that they originated from melting of depleted mantle wedge with sediment-derived fluid metasomatism and melting of deeply subducted sediment-bearing slab, respectively. This provides direct petrological and geochemical evidence for the onset of the Earth’s deep carbon cycle before 1.9 Ga, offering new insights into the carbonatite sources and the early history of the global carbon cycle.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"417 ","pages":"Article 107669"},"PeriodicalIF":3.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137498","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}