Precambrian Research最新文献

{"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, S. Balakrishnan, Rajneesh Bhutani, Nanila Sasi, A.Vipin Govind","doi":"10.1016/j.precamres.2025.107868","DOIUrl":"10.1016/j.precamres.2025.107868","url":null,"abstract":"<div><div>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 (>49), and positive Eu<sub>SN</sub>, La<sub>SN</sub>, and Gd<sub>SN</sub> 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.</div><div>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 (<sup>208</sup>Pb/<sup>204</sup>Pb vs. <sup>206</sup>Pb/<sup>204</sup>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 (<sup>208</sup>Pb/<sup>204</sup>Pb) ratios and low κ (<sup>232</sup>Th/<sup>238</sup>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.</div><div>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}

{"title":"Controls on organic-rich shale formation in the Mesoproterozoic Beetaloo Sub-basin, Northern Territory, Australia: insights from biogeochemistry and mineralogy","authors":"Yaser Noorian ,&nbsp;Juraj Farkaš ,&nbsp;Alan S. Collins ,&nbsp;Claudio Delle Piane ,&nbsp;P.Anthony Hall","doi":"10.1016/j.precamres.2025.107869","DOIUrl":"10.1016/j.precamres.2025.107869","url":null,"abstract":"<div><div>The Mesoproterozoic Velkerri shales (ca. 1400 Ma, million years) deposited in the McArthur-Yanliao Gulf of Nuna (preserved in northern Australia and north China) preserve high levels of organic carbon that have led to them being explored for hydrocarbons. In the Proterozoic-aged sub-basin in north of Australia, organic matter preservation coincides with mineralogical and chemical evidence for anoxic to euxinic bottom-water and/or sediment–water interface conditions, which were likely driven by the increased organic C content and associated O₂ consumption in the local environment. Whether this increase in organic matter formation/preservation is due to increased surface-water primary productivity, or simply because the seabed was starved of siliciclastic input due to relative sea-level change, remains controversial. To address these questions, here we present total organic carbon (TOC) data, organic carbon isotopic compositions (δ¹³C_org), and bulk mineralogy of shales from the sections through the Amungee Member of the Velkerri Formation, recorded and sampled from two correlative cores located in northeast and north of the basin (ca. 170 km apart). Similar δ¹³C_org and TOC profiles, lightest in the A-organofacies, peaking in the B-organofacies, and declining toward the C-organofacies top, suggest peak photosynthetic productivity in B-organofacies and dominant chemosynthetic input in A-organofacies. The high covariance between δ¹³C_org and TOC in Principal Component Analysis (PCA), particularly in PC1 (37.52 % of variations) and PC2 (20.9 % of variations) of B-organofacies in Marmbulligan-1, suggests a strong coupling between δ¹³C_org and TOC, indicating a common control on their variations. Stable δ¹³C_org values suggest steady bioactivity during the lean interval (intra B–C), though increased clastic input likely diluted TOC abundance. This is marked by an increased volume of presumably detrital clays/phyllosilicates (or rather their alteration products) such as chlorite content, particularly in the B–C interval. The role of detrital input in this interval is also evidenced by high correlation between chlorite and kaolinite minerals in PCA analysis. This heterolithic siliciclastic influx represents the distal Wyworrie delta, prograding northward across the basin.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"427 ","pages":"Article 107869"},"PeriodicalIF":3.2,"publicationDate":"2025-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144321720","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 Petrogenesis of late Archaean anorthositic chromitites: New insights from Fiskenæsset, Greenland and Sittampundi, India","authors":"S. Veni ,&nbsp;Hugh Rollinson ,&nbsp;Pierre Burckel ,&nbsp;Stephen Eggins ,&nbsp;Brian F. Windley ,&nbsp;Yann Sivry ,&nbsp;Maggi Loubser ,&nbsp;K. Sajeev","doi":"10.1016/j.precamres.2025.107830","DOIUrl":"10.1016/j.precamres.2025.107830","url":null,"abstract":"<div><div>We present the trace element data for chromites from the anorthositic chromitites at Fiskenæsset, Greenland and Sittampundi, India, using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), along with new major element analyses. Anorthositic chromitites are a rare petrological association consisting of highly calcic plagioclase (&gt;An90), calcic-amphibole, and iron-rich chromite, primarily restricted to the late Archaean (2900–2500 Ma). Unlike chromitites in komatiitic, oceanic, and layered intrusion settings, their formation remains poorly understood. Our study demonstrates that the Fiskenæsset and Sittampundi chromites have strikingly similar minor and trace element chemistry: although the Fiskenæsset chromites contain higher Mn, V and Ga and lower Ti, Ni, Zn, and Co than the Sittampundi chromites. UG2 Bushveld chromite normalized multi-element plot indicates that these chromites are depleted in Ti and Sc, consistent with crystallization from a melt undergoing amphibole fractionation. Cr#-Fe# variations further suggest that chromite composition was controlled by amphibole fractionation, reinforcing the role of magmatic amphibole in the genesis of anorthositic chromitites. We propose that the presence of water in the parent magma was critical for chromite crystallization, and as amphibole crystallized, reducing the water content of the melt, Cr solubility decreased, triggering chromite precipitation.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"427 ","pages":"Article 107830"},"PeriodicalIF":3.2,"publicationDate":"2025-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144313830","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 crustal-derived carbonatites in Trans-North China Orogen","authors":"Shi-Ying Wang ,&nbsp;Ben-Xun Su ,&nbsp;Jing Wang ,&nbsp;Shan-Ke Liu ,&nbsp;Wen-Jun Li","doi":"10.1016/j.precamres.2025.107824","DOIUrl":"10.1016/j.precamres.2025.107824","url":null,"abstract":"<div><div>Fengzhen Paleoproterozoic (1681 Ma) carbonatites, located in the Trans-North China Orogen (TNCO), are featured by an assemblage of calcite, phlogopite, clinopyroxene, olivine, apatite and barite, lacking pyrochlore or fenitization. Geochemically, they exhibit negative Eu anomalies in rare earth element patterns, sediment-like C-O isotopic signatures, and enriched initial Sr-Nd isotopic compositions, distinct from those of typical mantle-derived carbonatites. Phlogopite, the predominant Li-bearing phase in the carbonatites, shows heavier Li isotopic compositions (δ⁷Li = 4.87–10.87 ‰, mean value = 7.97 ± 1.53 ‰) than those in mantle-derived carbonatites worldwide. These δ⁷Li values align more closely with those of contemporary (meta)sedimentary carbonate rocks. These features collectively suggest a crustal origin of the Fengzhen carbonatites. Isotopic modeling indicates that parental magma of the Fengzhen carbonatites likely originated from melting of (meta)sedimentary carbonate rocks, with contributions from granites and pyroxenites during the Paleoproterozoic collision between Eastern and Western Blocks of the North China Craton. The crustal-like Li isotopic signatures of the Fengzhen carbonatites, along with their spatial proximity to the Daqingshan crustal-derived carbonatites, imply that additional Paleoproterozoic crustal-derived carbonatites may be present within the TNCO. This study supports the hypothesis that analogous crustal processes may generate carbonatite within orogenic belts and provides novel insights into crustal contributions to carbonatites.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"427 ","pages":"Article 107824"},"PeriodicalIF":3.2,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144307563","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 complex Pb inventory in Archean K-feldspars","authors":"N.J. McNaughton","doi":"10.1016/j.precamres.2025.107854","DOIUrl":"10.1016/j.precamres.2025.107854","url":null,"abstract":"<div><div>Lead isotope luminaries Ken Ludwig and Leon Silver in 1977 wrote: “… caution must be used in applying total-sample lead (isotopic) analyses to Precambrian feldspars to problems of lead-isotope evolution in crustal rocks”.<!--> <!-->Despite this, there continues to be published studies which make the assumption that the measured K-feldspar Pb isotopic composition in Archean igneous rock samples is representative of the initial Pb of their host granite (<em>s.l.</em>) and the granite source. Based on published Australian examples, this assumption is demonstrably wrong in a significant proportion of Archean cases, and it is likely that some subsequent interpretations proposing sources with unusually high model μ (²³⁸U/²⁰⁴Pb) in the Archean will not be confirmed when relevant testing data are available.</div><div>The Pb inventory in Archean K-feldspars comprises three main components: initial Pb, in-growth Pb from U-Th decay and remobilised Pb attained during later overprint events. The “two-point Pb-Pb isochron” age for the measured K-feldspar and hostrock Pb isotope compositions compared to the granite’s U/Pb age is recommended as a simple test for identifying remobilised Pb in Archean K-feldspar. Comparison of Pb isotope data measured by TIMS and Laser-MC-ICPMS on the same K-feldspar samples, and comparison of both to the formation isochron of their host granite, demonstrate examples where the K-feldspar data do not adhere to the formation isochron: the initial Pb of the granite should lie on the formation isochron. The sensitivity of this test is greatly improved by using optimum precision Pb isotope analyses for both the rock and K-feldspar. The Pb inventory of Archean K-feldspar is complex and should not be used for Pb isotope source characterisation and evolutionary studies without also measuring the Pb isotopes in the host granite and its age. The samples field attributes and petrography should be assessed to identify possible alteration or overprint events, as Pb mobility during alteration hinder preservation of the granite initial Pb isotope composition by K-feldspar in the Archean.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"427 ","pages":"Article 107854"},"PeriodicalIF":3.2,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144297670","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":"Changing pattern of continental crust generation from late Mesoarchean to early Paleoproterozoic: Record from the southeastern Bastar Craton, central India","authors":"Samyayan Ghosal ,&nbsp;Sukanta Dey ,&nbsp;Jaganmoy Jodder ,&nbsp;Manoj Kumar Sahoo ,&nbsp;Marlina A. Elburg","doi":"10.1016/j.precamres.2025.107835","DOIUrl":"10.1016/j.precamres.2025.107835","url":null,"abstract":"<div><div>The Earth underwent significant changes during the late Mesoarchean to early Paleoproterozoic period, such as the advent of modern-style plate tectonics and widespread formation and emergence of continental crust. However, the details of temporal variations in mechanisms of continental crust formation during this critical period have been widely debated. The present work addresses such issue by providing comprehensive insights through field, petrographic, whole-rock elemental, and in-situ zircon LA-MC-ICP-MS U-Pb-Hf isotope data on granitoids from the previously unexplored southeastern part of the Bastar Craton, India. The study area records the formation of a ∼ 2.86 Ga high-HREE sodic granitoid, and is interpreted to be a product of shallow partial melting of a juvenile mafic crust in an intraplate setting. Detrital zircon ages from a paragneiss suggest subsequent crust generation around 2.75–2.65 Ga, with a shift from juvenile crust formation to reworking of older crust at ∼ 2.70 Ga. Thereafter, widespread high-temperature reworking of significantly older (Eo- to Paleoarchean) crust at ∼ 2.48–2.47 Ga produced voluminous ferroan, LILE- and HFSE-enriched potassic granitoids with A-type characteristics. By synthesizing craton-wide information, our results point towards the subduction and accretion of various arc-related terrains at ∼ 2.5 Ga within the Bastar Craton. It is argued that the ∼ 2.48 Ga high-temperature, ferroan potassic granitoids were formed in an extensional geodynamic setting during post-orogenic uplift. This marks the termination of the compressive forces of subduction, leading to final cratonization. Finally, granitoid exhumation shed immature clastic sediments, now preserved as paragneiss in nearby basins, likely formed by post-collisional extensional collapse. Comparison with other well-studied cratons suggests a common pattern − an initial late Mesoarchean to early Neoarchean period of juvenile magmatism associated with non-plate tectonic regime, followed possibly by the advent of modern-style plate tectonics, terrain accretion, and granitoid diversification in the late Neoarchean.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"427 ","pages":"Article 107835"},"PeriodicalIF":3.2,"publicationDate":"2025-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144280713","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}