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The Zanhuang Complex is situated on the eastern margin of the Trans-North China Orogen, with the Huangcha Pluton being a constituent of this complex. To ascertain the nature of the approximately 2.5-billion-year-old Huangcha Pluton, crucial evidence for understanding its extensional setting was sought through petrogenesis and dating investigations. LA-ICP-MS dating of zircon from the granite yielded an age of (2488 ± 6) Ma. Primarily composed of porphyritic monzonite with sporadic melanocratic enclaves, the Pluton's phenocrysts are predominantly feldspar with minor quartz. The granite exhibits high SiO2 content (72.64%–74.16%) and alkali levels, with Na2O + K2O ranging from 7.59% to 9.07%, classifying it as a shoshonitic series with a slightly peraluminous feature. Enrichment in large-ion lithophile (LIL) elements (Rb, Th, and U) and depletion in Sr, V, Cr, Co, and Ni were observed, with high Rb/Sr and Ga/Al ratios ranging from 0.73 to 2.72 and 2.75 × 10−4 to 3.11 × 10−4, respectively. The rock exhibits high εNd(t) values, ranging from −0.06 to 0.88, with TDM2 ages falling between 2.79 and 2.87 billion years. Zircon grains display 176Hf/177Hf ratios ranging from 0.281266 to 0.281412 and εHf(t) values spanning from 0.96 to 6.18, calculated using the 207Pb/206Pb age. It is suggested that the Huangcha Pluton represents A-type granite formed via anatexis of the Neoarchean TTG in an extensional setting following orogenic processes. The formation of the Huangcha Pluton further corroborates the stabilization of the North China Craton towards the end of the Neoarchean. This finding supports the hypothesis that the North China Craton may belong to the Rae-family cratons, sharing similar magmatic and tectono-metamorphic records around ~2.5 billion years ago. [ABSTRACT FROM AUTHOR]

The Anshan–Benxi area, situated in the northeast of the North China Craton (NCC), is home to not only the oldest rocks in China (~3.8 Ga) but also a diverse range of granitoids dated between 3.8 and 2.5 Ga. The Lianshanguan batholith, covering an area of approximately 250 km2 with an east–west trend, predominantly consists of syenogranites (K2O > 4 wt. % and K2O/Na2O ratios > 1.3). Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U-Pb analyses of the two syenogranites yielded concordant ages of 2541 ± 22 and 2512 ± 13 Ma, respectively. These syenogranites had zircon εHf(t) values ranging from −20 to +4.9 with two-stage Hf model ages (TDM2(Hf)) spanning 3.9–2.7 Ga. Based on petrological, geochemical, and isotopic characteristics, we conclude that the Lianshanguan syenogranites are mainly resulted from the reworking of complicated Eoarchean–Mesoarchean crustal materials, possibly with a small proportion of ~2.7 Ga juvenile crustal materials. When compared with coeval syenogranites from the Northern Liaoning and Western Liaoning–Eastern Hebei areas, ~2.5 Ga syenogranites from the Anshan–Benxi area displayed more complicated TDM2(Hf) ages, hinting at a pronounced late Neoarchean reworking of the Eoarchean to Mesoarchean continental crust (including metasedimentary sources) primarily in the Anshan–Benxi region of the North China Craton. This scenario significantly bolsters the arc–continent collision model. [ABSTRACT FROM AUTHOR]

Multiple interpretations exist regarding the tectonic evolution model of the Neoarchean North China Craton, requiring a more in-depth study of metamorphic processes. Systematic petrographic observations, mineral chemical analysis, phase equilibrium modeling, and zircon dating were conducted on the basic granulites from Qingyuan in northern Liaoning to elucidate their metamorphic evolution processes and geological significance. The selected samples of mafic granulites were divided into the garnet-bearing domain (19DJ07-GD) and garnet-free domain (19DJ07-NGD), with the garnet-bearing region displaying a banded and inhomogeneous distribution. Both domains exhibit two generations of granulite facies assemblages. In the garnet-bearing domain, the first-generation metamorphic mineral assemblage includes garnet + clinopyroxene + orthopyroxene + hornblende + biotite + plagioclase + quartz. Notably, the first-generation plagioclase (Pl1 ) exhibits a complex compositional zoning, with anorthite content (xAn ) increasing from the core to the mantle and then decreasing towards the rim. Similarly, the titanium component zoning in the first-generation amphibole (Amp1 ) follows a pattern of increasing from the core to the mantle and then decreasing towards the rim. Based on mineral assemblages and corresponding component zoning, it is inferred that the first-generation granulite facies metamorphic process followed a counterclockwise P-T path, involving a pre-peak P-T rise stage and a post-peak P-T drop stage. Phase equilibrium modeling constrains the peak conditions at 0. 8 ~ 0. 9 GPa/ 900 ~ 950 °C, indicative of high-ultrahigh-temperature ( HT-UHT) metamorphism conditions. Zircon dating results yielded a post-peak cooling age of 2498±6. 9 Ma (MSWD= 0. 39). Considering the regional "dome-and-keel" tectonics, the counterclockwise P-T path, and the metamorphic timing of supracrustal rock nearly synchronous with late-stage TTG magmatic pulses, the UHT metamorphism of the supracrustal rocks is believed to be controlled by the unique Archean vertical tectonics/ sagduction system. The second-generation metamorphic assemblage is characterized by locally formed coronas or symplectites of garnet + quartz ± clinopyroxene, representing high-pressure ( HP ) granulite facies metamorphism associated with a Paleoproterozoic orogenic event. [ABSTRACT FROM AUTHOR]

In order to enhance the understanding of Archean continental crust formation and evolution history of Liaonan block in North China Craton, the Neoarchean TTG(tonalite-trondhjemite-granodiorite)gneisses in Shijianfang area of Liaonan block were focused on, and the detailed field investigation, zircon U-Pb dating and Lu-Hf isotope analysis, and whole-rock geochemical analysis were intergrated. The results show that TTG gneiss in Shijianfang area crystallizes at(2 499.7±5.4)Ma. The TTG gneiss samples have high contents of SiO2(66.1%-69.1%)and Al2O3(14.6%-15.6%), are enriched in Na and depleted in K(K2O/Na2O is 0.41-0.51)with weakly positive Eu anomalies(1.06-1.59); the samples are relatively enriched in large ion lithophile elements(Ba, Rb, K, etc.)and high field strength elements(Zr, Hf, etc.), featured by high Sr/Y(44.3-69.5)and(La/Yb)N(11.8-24.0), and depleted zircon Hf isotopic composition with two-stage model ages of 2 903-2 687 Ma. Compared with TTG rocks derived from partial melting of the thickened lower crust, TTG gneisses in Shijianfang area have relatively higher contents of MgO, Cr and Ni. The above geochemical characteristics reveal TTG gneisses in Shijianfang area are typical medium-pressure TTG rocks, which is the product of partial melting of Meso-Neoarchean basaltic crust. The source area is rich in garnet and amphibolite, but short of rutile and plagioclase. Combined with previous studies, TTG gneisses in Shijianfang area are likely formed by the partial melting of subduction slabs, indicating the warm subduction tectonic system of the ancient continental margin. The North China Craton might be controlled by both plate tectonics and mantle plume tectonics during Late Neoarchean. [ABSTRACT FROM AUTHOR]

The Bayan Obo–Duolun–Chifeng–Kaiyuan (BDCK) Fault is considered the boundary between the North China Craton (NCC) and Central Asian Orogenic Belt (CAOB). However, the site of this boundary from Duolun to Chifeng and Kaiyuan remains highly controversial. Here, we present an integrated study of petrology, whole‐rock geochemistry, and zircon U–Pb and Sr–Nd–Hf isotope compositions for tonalites and amphibolites in the Bainaimiao arc belt (BAB) to better constrain the northern NCC margin. The tonalites are similar to NCC tonalite–trondhjemite–granodiorites (TTGs), characterized by relatively high Na2O/K2O and Sr/Y ratios and fractionated rare earth element (REE) patterns, with high light REE (LREE) but low heavy REE (HREE) concentrations. Laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) zircon U–Pb dating yields formation ages of 2599–2674 Ma, with a weighted average of 2649.6 ± 3.7 Ma. The εHf(t) values (3.5–7.5), two‐stage model ages (2673–2793 Ma), whole‐rock positive εNd(t) values (1.3–1.9), and two‐stage model ages (2841–2880 Ma) suggest that the Neoarchean tonalites likely originated from remelting of thickened Meso‐Neoarchean mafic crust. LA–ICP–MS U–Pb isotope data reveal that the amphibolites formed at ~2610 Ma. They have high‐Fe tholeiitic compositions and are close to normal mid‐ocean ridge basalt (N‐MORB)‐like rocks, indicating that they were generated from partial melting of the depleted mantle. The existence of Neoarchean basement rocks, combined with seismic and isotope data, suggests that the Jiefangyingzi area is part of the Trans‐North China Orogen (TNCO) in the NCC rather than part of the CAOB and that the northern boundary of the NCC in Chifeng is located north to the Jiefangyingzi area. [ABSTRACT FROM AUTHOR]

The Alxa Block is the westernmost part of the North China Craton (NCC), and is regarded as one of the basement components of the NCC. Its geological evolution is of great significance for the understanding of the NCC. However, the Precambrian basement of the Alxa Block is still poorly studied. In this study, we present new in situ LA‐ICP‐MS zircon U‐Pb and Lu‐Hf isotope data from the Diebusige Metamorphic Complex (DMC) which located in the eastern Alxa Block. Field and petrological studies show that the DMC consists mainly of metamorphic supracrustal rocks and minor metamorphic plutonic rocks and has experienced amphibolite‐granulite facies metamorphism. Zircon U‐Pb dating results suggested that the amphibolite sample yields a crystallization age of 2636 ± 14 Ma and metamorphic ages of 2517–2454 Ma and 1988–1952 Ma, proving the existence of exposed Archean rocks in the Langshan area and indicating that late Neoarchean to Paleoproterozoic metamorphic events existed in the Alxa Block. Two paragneiss samples show that the magmatic detrital zircons from the DMC yield 207Pb/206Pb ages ranging from 2.48 Ga to 2.10 Ga with two youngest peaks at 2.13 Ga and 2.16 Ga, respectively, and they were also overprinted by metamorphic events at 1.97–1.90 Ga and 1.89–1.79 Ga. Compilation of U‐Pb ages of magmatic detrital and metamorphic zircons suggested that the main part of the DMC may have been formed at 2.1–2.0 Ga. Zircon Lu‐Hf isotope data show that the source materials of the main part of the DMC were originated from the reworking of ancient Archean crust (3.45–2.78 Ga). The Hf isotope characteristics and the tectonothermal event records exhibit different evolution history with the Khondalite Belt and the Yinshan Block and the other basements of the Alxa Block, indicating that the Langshan was likely an independent terrain before the middle Paleoproterozoic and was subjected to the middle to late Paleoproterozoic tectonothermal events with the Khondalite Belt as a whole. [ABSTRACT FROM AUTHOR]

• The metabasites and TTG gneiss in the Linshan complex mainly formed at 2.6–2.5 Ga. • The metabasites in the Linshan complex formed in a Neoarchean back-arc basin. • There may have been several Neoarchean "forearc-arc-backarc" systems in the NCC. The onset of plate tectonics and crustal growth processes in the early Earth have been controversial scientific issues in the geoscience. The North China Craton (NCC) preserves widespread 3.8–2.5 Ga rocks, providing an ideal place to understand early continent formation and evolution. The Linshan complex located in the southern segment of the Central Orogenic Belt (COB) of the NCC, is mainly composed of TTG (tonalite-trondhjemite-granodiorite)-diorite gneisses and metamorphic volcanic-sedimentary units dominated by gabbro, basalt, basaltic andesite and biotite-plagioclase gneiss. Detailed mapping on the scale of 1:100 of a structural transect shows that the Linshan complex has mainly experienced two major deformation events including top-to-the-SE thrust faults and late NE-trending high-angle normal faults. Detailed zircon U-Pb dating shows that gabbro, basaltic andesite, and TTG gneiss mainly formed at ca. 2.52–2.50 Ga. Gabbros and basalts display enrichment of LREE and negative Nb and Ta anomalies, and basaltic andesites display mixed MORB-IAT geochemical affinities. Basalts and basaltic andesites are members of the Nb-enriched basalt series with high absolute Nb contents (>6 ppm). TTG gneisses are geochemically divided into high-pressure and low-pressure TTGs. High-pressure TTGs are characterized by high ratios of La/Yb cn (26.29–45.73) and fall into the adakitic region in the La/Yb cn -Yb cn diagram. Considering the close contact with Nb-enriched basaltic series, it is proposed that high-pressure TTGs may have formed by partial melting of a subducting oceanic slab with garnet and amphibole and/or rutile as residues. Low-pressure TTGs are characterized by low ratios of La/Yb cn and Sr/Y with marked negative Eu anomalies, indicating partial melting at shallow crustal levels. Regional tectonic relations have defined the Neoarchean Dengfeng island arc-forearc accretionary complex to the east of the Linshan complex. Thus, we propose that the gabbros-basalts-basaltic andesites in the Linshan complex mostly formed in a Neoarchean suprasubduction back-arc basin by rifting of a TTG-dominated island arc terrane. The final closure of the back-arc basin resulted in their tectonic juxtaposition forming thrust-imbricated structures. There may have been several Neoarchean "forearc-island-arc-backarc" systems in the NCC that are similar to modern accretionary tectonic orogens, indicating that plate tectonics has been in operation since at least 2.55–2.50 Ga. [ABSTRACT FROM AUTHOR]

• A calc-alkaline bimodal volcanic complex in the Yinshan Block was formed at ∼ 2570 Ma. • The high-Mg basalt/andesite were derived from a metasomatised depleted mantle. • The adakitic rhyolites were derived from a thickened juvenile mafic lower crust. • This bimodal complex was formed in a modern-style arc setting. Plate tectonics plays an important role in Earth's evolution, but it is a difficult and controversial issue to trace the operation of plate tectonics in the Archean. Calc-alkaline magmas are a diagnostic feature of modern subduction-related magmatism and thus identification of Archean subduction-related calc-alkaline magmas is crucial for understanding when Archean plate tectonics operated. Here we present zircon U-Pb, whole-rock geochemical and Sr-Nd isotopic data for a metamorphosed Neoarchean calc-alkaline bimodal volcanic complex from the Yinshan Block, the North China Craton. Zircon U-Pb dating results indicate that these meta -volcanic rocks were erupted in the late Neoarchean (∼2570 Ma). Its mafic unit is characterized by high contents of K 2 O (0.68–4.20 wt%), MgO (Mg# = 62.0-73.4), Cr (332-904 ppm), Ni (105-269 ppm), and is enriched in light rare earth elements (REEs), but depleted in heavy REEs and Nb, Ta and Ti. These geochemical features are similar to those of high-Mg basalts in the Phanerozoic arc setting. They have positive ε Nd (t) values (+1.3 to + 2.4), indicating that they were derived from the depleted mantle wedge. The felsic unit has variable K 2 O content (1.42–4.95 wt%) and K 2 O/Na 2 O ratios of 0.23–1.36 with positive ε Nd (t) values (+0.7 to + 3.1). They show characteristics of modern adakites with high Sr/Y and La N /Yb N ratios, suggesting that they were generated by partial melting of the thickened juvenile mafic lower crust. We conclude that the studied Neeoarchean bimodal meta -volcanic complex was formed during subduction-zone retreating and root delamination in a Neoarchean arc. Our results further indicate that plate tectonics had already operated in the Neoarchean in the Yinshan Block. [ABSTRACT FROM AUTHOR]

The Songling and Majiayu peridotite blocks occur in the Eastern Block, North China Craton (NCC). Geothermobarometry data show that the Songling peridotites began exhumation from a depth of c. 70 km (c. 23 kbar). During exhumation, the Songling peridotites were intruded by an upper-crust-derived, high-δ18O (up to +7.28‰ in zircon) trondhjemitic dyke at 2.47 Ga and experienced granulite-facies metamorphism. The Songling peridotites have hybrid mantle wedge (HMW) -like high SiO2 (> 45 wt%), high FeOt (c. 10 wt%) content, high modal orthopyroxene abundance (> 35%) and high ϵNd(t) (+18.4 to +21.4), which were generated by the reaction between peridotite and eclogite-derived melts. The clinopyroxenes from the Songling peridotites were in equilibrium with a Nb-, Zr- and Ti-depleted arc-like magma. The Majiayu peridotites are characterized by depletion of Nb, Zr and Hf and are highly enriched in FeOt, Th and light rare earth elements (LREEs), which can be interpreted as an open system reaction between hydrous melts and fore-arc mantle peridotites. These two peridotite blocks are considered to be arc-related mantle peridotites that experienced melt extraction and metasomatism in different styles. They were exhumed to the north margin of the North China Craton during the c. 2.47 Ga arc–continent collision along the Zunhua structural belt. [ABSTRACT FROM AUTHOR]

Crystalline basement and Precambrian crustal growth of the continental massifs within the Central Asian Orogenic Belt (CAOB) are still pending problems. Our geological and geochemical investigations identified an Archean (2606 Ma) granitic pluton in the Biliya area of the Erguna Massif. The Neoarchean granitoids show high and positive in‐situ zircon ∊Hf(t) (+0.3 to +10.0), whole‐rock ∊Nd(t) (+4.8) and whole‐rock ∊Hf(t) values (+2.1). They are characterized by high Y + Ce + Zr + Nb (> 220 ppm) and Zr contents and could be classified as A‐type granites. These granitoids are characterized by high Zr saturation temperatures (TZr) (796–836°C). They were derived from partial re‐melting of juvenile mafic lower crust in an intracontinental back‐arc extensional environment. This newly identified Neoarchean granitic pluton may represent the crystalline basement of the several continent massifs within the CAOB, and their high ∊Hf(t)–∊Nd(t) values may also indicate the occurrence of lateral crustal growth events in these massifs during the Neoarchean. [ABSTRACT FROM AUTHOR]

The cratonization history of the North China Craton (NCC) and the nature of tectonothermal events are still highly controversial. Tonalite-trondhjemite-granodiorite (TTG) gneisses, as the dominant lithological assemblages in Archean metamorphic terranes, can provide significant clues to the magmatic and metamorphic evolution of Precambrian crust. This study presents zircon laser-ablation inductively-coupled-plasma mass spectrometry U–Pb ages, trace-element, and in-situ LA-MC-ICP-MS zircon Hf isotope data for the TTG gneisses from the Bengbu-Wuhe area on the southeastern margin of the NCC. Cathodoluminescence images and trace elements indicated that magmatic zircons display the characteristics of euhedral-subhedral crystals with oscillatory growth zoning structures, high ΣREE contents, marked Ce positive anomalies, and Pr–Eu negative anomalies. The metamorphic zircons display the spherical-oval crystals with distinct core-rim structures, high and homogeneous luminescent intensity, lower ΣREE, Nb, Ta, Hf contents, relative flat REE patterns, weak Ce positive anomalies, and Pr-Eu negative anomalies. The Ti–in–zircon geothermometer data indicate that the crystallization temperature of the TTG gneiss ranged from 754 to 868 °C. Zircon U–Pb ages indicate that the TTG gneisses formed at 2.79–2.77 Ga and 2.50 Ga and underwent metamorphism at 2.57–2.52 Ga. The Hf isotopic data indicate that the magmatic zircons exhibit high, positive εHf(t) values close to those of the coeval depleted mantle, whereas the metamorphic zircons exhibit negative or nil εHf(t) values. This implies that the TTG gneisses were derived from the partial melting of the ~ 2.9–2.6 Ga juvenile crustal sources mixed with ~ 3.0–2.8 Ga ancient crustal materials. Combined with the regional tectonic evolution, we propose that the metamorphic basement at the southeastern margin of the NCC underwent episodic crustal growth at ~ 2.7 and ~ 2.5 Ga and subsequently underwent crustal reworking or re-melting of the ancient crust during the Neoarchean. The Neoarchean TTG gneisses might have been derived from the partial melting of lower crustal materials related to plate subduction. [ABSTRACT FROM AUTHOR]

The source characteristics and depositional environments of banded iron formations (BIFs) can provide key information on the chemical composition, redox environment, and tectonic evolution of early Precambrian paleo-oceans. Large quantities of Neoarchean to Paleoproterozoic BIFs are exposed in the North China Craton (NCC). This study focuses on petrography, major and trace element geochemistry, zircon U-Pb geochronology, and Sm-Nd isotopic compositions of a set of Neoarchean BIF-bearing sedimentary rocks preserved in the Zanhuang Massif of the NCC, including comparison with Archean to Paleoproterozoic BIFs throughout the NCC. This study provides constraints for deciphering the paleo-ocean chemical composition, redox environment and relationship between the geological-environments co-evolution and the formation of the BIFs in the NCC. The Zanhuang BIFs are mainly composed of quartz and magnetite, with small amounts of grunerite, actinolite (ferroactinolite) and garnet in the Fe-rich bands, and are classified as Algoma-type. Zircon U-Pb ages of the metasedimentary rocks interbedded with the BIFs indicate that the Zanhuang BIFs formed at ∼2.51 Ga and were subjected to metamorphism at ∼2.47–2.48 Ga. Most BIFs have low contents of Al 2 O 3 , TiO 2 and high field strength elements Zr, Hf, Th and U, indicating that they are pure chemical sedimentary rocks. The BIFs are characterized by depleted light rare earth elements (LREEs) and positive La and Y anomalies, which are similar to the geochemical characteristics of modern seawater. The absence of Ce anomalies and the low (Pr/Yb) SN ratios indicate an anoxic state of the ocean. The Zanhuang BIFs precipitated from a mixture of minor high-temperature hydrothermal fluids and seawater mixed with continent-derived freshwater (∼10–20%) or other additional fluids such as ocean crust-derived fluxes indicated by Eu anomalies and Y/Ho and Sm/Yb ratios. The variable initial ε Nd (t) values of Zanhuang BIFs suggest complex and dynamic input of continental crustal fluxes. The statistical comparison with other BIFs shows that the peak formation ages of the Archean to Paleoproterozoic BIFs in the NCC is ∼2.54 Ga. Most of the BIFs in the NCC are Algoma-type, while a few Paleoproterozoic BIFs are Superior-type. A mixture of <0.1%–1% of modern seafloor high-temperature hydrothermal and seawater can account for the REE + Y characteristics of the BIFs, while ε Nd (t) values suggest possible contributions from continental sources. The Eu anomalies indicate that ∼2.7 Ga and ∼ 2.55 Ga are the two peaks of submarine hydrothermal and magmatic activities of the NCC, which correspond to crustal growth and subduction-collision events in the NCC, respectively. The Ce anomalies and Fe isotopes indicate the transition from an anoxic ocean with possible regional oxygen oases before 2.5 Ga to a redox-stratified ocean during the GOE. Most Neoarchean BIFs of the NCC were formed in island arc-related tectonic settings, while the Paleoproterozoic BIFs likely reflect environments of rifting to subduction in the NCC. [ABSTRACT FROM AUTHOR]

The Neoarchean charnockites of North margain of North China Craton (NCC) has become a hot topic into understanding the Early Precambrian basement. Although there is a broad consensus that charnockite is usually related to granulite facies metamorphism, whether its petrogenesis and tectonics characteristics remains controversial. Inclusions within hypersthene and garnet in charnockite are used to identify the peak granulite facies mineral assemblage, with the formation of Magnesian–charnockite attributed to anatexis of the protolith associated with this granulite facies metamorphism. The distribution of major and trace elements in charnockite is very uneven, significant depleted in LILEs (eg. Cs, U, Th) and HFSEs (eg. Nb, Ta, P and Ti), riched in Sr. Raising to the coexistence of Eu–enrichment and Eu–depletion type of REE patterns that influenced by the content of plagioclase and the remnants minerals of zircon and apatite. Comparative the petrography, geochemistry and geochronology data of Magnesian–charnockite indicate that the ratios of mafic pellites and basalts involved in anatectic melting are different by the upwelling of mantle magma, also resulting in the Eu anormals characteristics. The formation of the Magnesian–charnockite is closely connected with the subduction of the NCC oceanic crust (About ∼2.5 Ga). However, Ferroan–charnockite may be the formed by the crystallization differentiation of the upwelling of mantle–derived shoshonitic magma (About ∼2.45 Ga), with the lower crust material addition. [ABSTRACT FROM AUTHOR]

• Basalts and andesites formed at ∼2535–∼2486 Ma, followed by crustal anatexis at ∼2489 Ma. • The mafic rocks were produced by partial melting of the pyroxene-rich subarc mantle domains. • The basalts and andesites were most likely formed in a continental arc setting rather than an oceanic arc setting. • Plate subduction and mafic arc magmatism in the North China Craton can be traced back to at least 2.65 Ga. • The 2.6–2.5 Ga event manifested as widespread accretionary orogenesis in Eastern North China. The North China Craton suffered a strong tectonothermal event in the late Neoarchean, with its crystalline basement dominantly composed of ca. 2.6–2.5 Ga granitoid gneisses and metamorphosed volcano-sedimentary sequences. However, controversial issues have long existed on the geodynamic setting of this event. We present new in-situ LA-(MC-) ICP-MS zircon U-Pb and Lu-Hf isotope data, and whole-rock geochemical data for Neoarchean magmatic rocks from the Lüliang Complex. Zircon U-Pb dating reveal that the basalts, andesites and felsic volcanics yield crystallization ages of 2535–2486 Ma, followed by crustal anatexis and metamorphism at ∼2489 Ma. The basalts and andesites yield positive ε Hf (t) values of 5.1–11.6 and 2.2–6.5 for zircons, corresponding to average Hf model ages of 2547 Ma and 2660 Ma, respectively. The felsic volcanic rock yields positive zircon ε Hf (t) values of 1.4–6.3, with Hf model ages averaging 2775 Ma. Such ages are consistent with 207Pb/206Pb ages of 2.8–2.7 Ga for relict zircons, indicating reworking of crustal rocks. The basalts and andesites have geochemical compositions of island arc tholeiite (IAT) and calc-alkaline basalt (CAB), suggesting that they were both derived from partial melting of subarc mantle sources that were generated by metasomatic reaction of the mantle wedge peridotite with subducting crust-derived fluids. Compared with the basalts, the andesites were also originated from a subarc mantle source with incorporation of more subducting sediment-derived melts. Thus, both the basalts and andesites would most likely form in a continental arc setting. In this regard, plate subduction and arc magmatism in the North China Craton can be traced back to at least 2.65 Ga in the Lüliang area. The 2.6–2.5 Ga tectonothermal event manifested as widespread accretionary orogeny in the North China Craton, resulting in significant growth of the juvenile mafic crust as well as extensive reworking of the old basement dominated by 2.8–2.7 Ga crustal rocks. [ABSTRACT FROM AUTHOR]

The Neoarchean charnockite of Yinshan Block has been a hot topic into understanding the Precambrian geology of the North China Craton. Although there is a broad consensus that the charnockite is usually related to granulite‐facies metamorphism, its petrogenesis and tectonics still remain controversial. We present a comparative study of the petrography, geochemistry, and geochronology of charnockite and intermediate–basic granulite in the Jining area along the northern margin of the North China Craton. Inclusions within hypersthene in charnockite are used to identify the peak granulite facies mineral assemblage, with the formation of charnockite being attributed to anatexis of the protolith associated with this granulite‐facies metamorphism. Anatexis occurred mainly during postpeak isothermal decompression, as inferred from the metamorphic evolution and pressure–temperature conditions (granulite and charnockite record peak pressure–temperature conditions of 750°C–1,000°C and 0.8–1.2 GPa and 850°C–975°C and 0.9–1.0 GPa, respectively) derived from analyses of metamorphic minerals using electron probe microanalysis, combined with previous zircon geochronology. Hypersthene in charnockite is interpreted to be a residual or peritectic mineral phase that was present during anatexis, and the charnockite is inferred to have been crystallized from a melt containing abundant residual minerals. Charnockite has similar geochemical characteristics to those of intermediate–basic granulite but differs in several key ways: (a) The charnockite is strongly depleted in the large‐ion lithophile element Cs, the heat‐producing elements U and Th, and the high‐field‐strength elements Nb, Ta, P, and Ti; (b) it is enriched in Sr; and (c) it exhibits both positive and negative Eu anomalies, which are characteristics of granites formed largely by in situ anatexis. Geochemical constraints indicate that the intermediate charnockite and retrograde metamorphic biotite–hornblende gneiss may both be the product of mantle‐derived magma in a magmatic subduction‐related back‐arc extensional environment. This setting provided a hot spot for metamorphic anatexis, with additional heat being provided by the upwelling of asthenospheric mantle. After the cessation of subduction by ~2,470 Ma, a magmatic arc extensional setting developed in the Jining area. The charnockite was involved in Paleoproterozoic orogenesis in the North China Craton and was strongly modified by a ~1,950‐Ma metamorphism event. [ABSTRACT FROM AUTHOR]

• Volcanic lithologies in the Qingyuan greenstone belt formed during 2.57–2.53 Ga. • A Neoarchean continental arc setting in the Qingyuan greenstone belt. • Volcanic assemblages recorded tectonic regime changing from compression to extension. • VMS mineralization is related to an arc rifting event where FII-type dacites formed. The Qingyuan greenstone belt (QGB) situated in the northeastern section of the North China Craton (NCC) is considered to be the unique metallogenic province in China that hosts both banded iron formations (BIFs) and volcanogenic massive sulfide (VMS) deposits. Traditionally, the QGB is divided into the Hunbei and Hunnan terranes separated by the Hunhe fault and grouped into the lower Shipengzi, middle Hongtoushan, and upper Nantianmen formations, which have undergone amphibolite- to granulite-facies metamorphism. Exposed supracrustal rocks are composed of plagioclase amphibolite and biotite plagioclase gneiss with minor amounts of BIF, marble, and schist. In this study, detailed field and petrographic observations, lithogeochemical, U-Pb geochronological, as well as whole-rock Sm-Nd isotope analyses were conducted on the metamorphosed mafic and felsic volcanic rocks (i.e. plagioclase amphibolite and biotite plagioclase gneiss, respectively) in the QGB in order to discuss implications for tectonic evolution and comitant VMS mineralization. The supracrustal rocks of both Hunbei and Hunnan regions were formed synchronously from 2.57 to 2.53 Ga and then had undergone 2.52–2.48 Ga regional metamorphism. Specifically, the lower section of the Shipengzi Formation is composed dominantly of transitional-tholeiitic basalts with negative Nb anomalies, suggesting that they were likely generated by partial melting of a mantle source that was previously altered by variable amounts of slab-derived fluids or melts. In contrast, the lithologic assemblages grade upward into interlayered bimodal volcanic rocks (i.e. N-MORB-type tholeiitic basalts and FI- to FII-type dacites of transitional to calc-alkalic affinities), representing a change in tectonic regime related to subduction from compression to extension. Among them all the basalts are characterized by consistently positive initial Nd compositions (ε Nd (t) = +2.7 to +3.4) further indicate a depleted mantle source; whereas those dacites possess negative to positive initial Nd values (ε Nd (t) = −4.6 to +3.0), suggesting they were formed by partial melting of depleted mafic source (likely lower mafic crust) and accompanied with variable addition of old crustal material. Significantly, VMS deposits are genetically linked to this extensional event and closely associated with the FII-type dacites that were generated by higher melting degree at high-temperature conditions and shallow crustal level (likely 10–15 km). In all, geochemical features (e.g., negative Nb anomalies and ε Nd value), together with contamination from continental crusts for tholeiitic mafic rocks and inherited zircons from these volcanic rocks, imply a continental arc setting where the QGB was evolved. [ABSTRACT FROM AUTHOR]

Archean high-K granitoids, generally formed after tonalite-trondhjemite-granodiorite (TTGs), are important for understanding crustal reworking of ancient cratons. The Linshan Archean high-K granitoids from the southern Trans-North China Orogen (TNCO) provide a window into the continental crustal evolution of the North China Craton (NCC). They mainly consist of monzogranite and granodiorite which were formed during 2 542–2 503 Ma. The high-K granitoids have high SiO2 (65.86 wt.%–78.08 wt.%), K2O (3.29 wt.%–7.62 wt.%) and low P2O5 (0.01 wt.%–0.27 wt.%). They display right inclined REE patterns with negative Eu anomalies (Eu/Eu*=0.20–0.81). Their spider diagram is characterized by enrichment of Rb, K, Th, U and depletion of Nb, Ta, Zr, Ti. The rocks have positive and variable zircon eHf(t) (+2.5 to +6.6) and whole-rock eNd(t) (+0.7 to +4.5) with two-stage model ages (TDM2Hf=2.87–2.64 Ga; TDM2Nd=2.77–2.50 Ga) similar to those of the Archean TTG-type rocks, amphibolites and diorites in the area. These evidences suggest that the high-K granitoids were produced by partial melting of juvenile crustal rocks. The Linshan high-K granitoids show relatively high whole-rock zircon saturation temperatures (694–889 ºC) and low Sr/Y ratios (0.27–21.1), indicating low pressure partial melting. Combined with other geological evidences, the Linshan high-K granitoids are suggested to have been produced by partial melting of the continental crust in a post-collision extensional environment after an arc-continent collision. Thus, the NCC did not amalgamate together until ca. 2.5 Ga. Compiled zircon U-Pb ages and Hf isotopes reveal that the ca. 2.5 Ga magmatism represents reworking of the continental crust. [ABSTRACT FROM AUTHOR]

[Display omitted] • This study reports the first identification of ca. 2.5 Ga and ca. 2.1 Ga charnockites in Zhuozi. • The ca. 2.5 Ga and ca. 2.1 Ga charnockites are homologous (Mesoarchean to Neoarchean TTGs and related intermediate-mafic rocks). • The ca. 2.5 Ga and ca. 2.1 Ga charnockites were formed at relatively high-pressure (subduction-collision) and low-pressure (intracontinental rifting) conditions, respectively. • The precursor of the Khondalite Belt may experience a subduction-collision process at ca. 2.6–2.45 Ga, followed by a long-term intracontinental rifting at ca. 2.45–2.0 Ga before the final subduction-collision at ca. 2.0–1.9 Ga. The Khondalite Belt (KB), a Paleoproterozoic collisional orogen in the North China Craton (NCC), lacks a well-established pre-collisional tectonic evolution due to the paucity of late Neoarchean to middle Paleoproterozoic magmatic rocks. This study focuses on the poorly dated charnockites in the Zhuozi area, the eastern segment of the KB. Through an integrated field investigation, petrography, SHRIMP and LA-ICP-MS zircon U-Pb dating, zircon Lu-Hf isotopic analysis, and whole-rock geochemistry, this study determines the formation ages, petrogenesis, and tectonic settings of the targeted charnockites, and further constrains the Neoarchean to Paleoproterozoic tectonic evolution of the KB. The charnockites crystallized at ca. 2.5 Ga and ca. 2.1 Ga and were metamorphosed at ca. 1.9 Ga. The ca. 2.5 Ga charnockites are magnesian and exhibit high Ba-Sr affinity, with SiO 2 , MgO contents and Mg# values of 66.20–71.43 wt%, 1.10–2.34 wt% and 34–49, respectively. Most samples are enriched in light rare earth elements (LREEs), Ba, Sr (Sr/Y = 11.79–34.94), and Eu (Eu/Eu* = 0.56–1.67), but depleted in heavy rare earth elements (HREEs, La N /Yb N = 10.14–42.81), Th, Nb, Ta, P, and Ti. The magmatic zircons have ε Hf (t) ranging from + 2.8 to + 5.8 and Hf model ages (T DM2) of 2711–2822 Ma. In comparison, the ca. 2.1 Ga charnockites are ferroan and exhibit A-type granite affinity, with higher SiO 2 (73.23–77.73 wt%) but lower MgO (0.03–0.27 wt%) contents and Mg# values (2–13). Most samples are enriched in LREEs, Rb, Zr, and Hf, but depleted in HREEs (La N /Yb N = 12.72–23.41), Nb, Ta, Sr (Sr/Y = 1.51–5.58), P, Ti, and Eu (Eu/Eu* = 0.24–1.11). The magmatic zircons have ε Hf (t) ranging from −4.0 to +0.8 and T DM2 of 2749–2916 Ma. The available data suggest that the two episodes of charnockites are homologous (Mesoarchean-Neoarchean TTGs and related intermediate-mafic rocks), with ca. 2.5 Ga and ca. 2.1 Ga charnockites formed at relatively high-pressure (subduction-collision) and low-pressure (intracontinental rifting) conditions, respectively. Combined with previous studies, the precursor of the KB may experience a subduction-collision process at ca. 2.6–2.45 Ga, followed by long-term intracontinental rifting events at ca. 2.45–2.0 Ga prior to the final subduction-collision at ca. 2.0–1.9 Ga. [ABSTRACT FROM AUTHOR]

There are different viewpoints on metamorphic and anatectic zircons recording ages of 2.45–2.48 Ga or even younger in some areas of the North China Craton where both late Neoarchean and late Paleoproterozoic tectono-thermal events are well developed. These are: 1) partial resetting of the U-Pb isotopic system in the late Neoarchean zircons, 2) metamorphism lasting from the late Neoarchean to the earliest Paleoproterozoic, and 3) earliest Paleoproterozoic metamorphism as separate different event. Western Shandong Province is an area where the late Neoarchean tectono-thermal event is widely developed but the late Paleoproterozoic event has not been identified. This provides an opportunity to understand the geological processes around the Archean-Proterozoic boundary. Based on a field study, we carried out SHRIMP U-Pb zircon dating on seventeen samples of ∼2.5 Ga old metamorphic and anatectic rocks, including tonalite, trondhjemite, granodiorite, gabbro, quartz diorite, granite and paragneiss with primary emplacement or depositional ages of 2.52–2.68 Ga. Anatectic zircons show some textural and compositional features: a) Homogenous or blurred oscillatory zoning, b) high U contents and low in Th/U ratios (commonly <0.3), c) rare idiomorphic morphologies, and d) commonly containing inherited (xenocrystic) cores. We conclude that the strong late Neoarchean event is widespread in western Shandong and is limited between ∼2.50 and 2.54 Ga. In contrast, apparent 2.45–2.48 Ga metamorphic zircon ages in some other areas of the North China Craton may be the result of overprinting and partial recrystallization of Neoarchean metamorphic zircons during the late Paleoproterozoic event. The Archaean rocks of western Shandong can be divided into three belts, namely Belts A, B and C from the northeast to the southwest. The difference between Belts A and B in ∼2.5 Ga metamorphic and anatectic intensity may indicate that the former was elevated to a higher crustal level compared with the latter at the end of the Neoarchean. [ABSTRACT FROM AUTHOR]

The diversity and petrogenesis of Archean granitoid rocks, including tonalite-trondhjemite-granodiorite suites (TTGs), sanukitoids, and K-rich granites, is essential to understanding the geodynamic process of crust-mantle interaction and the origin and evolution of the continental crust. In this study, we investigate the petrogenesis, geochronology, and Sr-Nd-Hf isotopes of Neoarchean granitoids from the Huai'an Complex in the North China Craton (NCC) to gain insight into the crustal evolution during the Late Neoarchean–Early Paleoproterozoic. Five groups of plutonic gneisses of dioritic-tonalitic-trondhjemitic (DTT) and granitic gneisses in the Huai'an Complex are distinguished by their compositions. LA-ICP-MS zircon U-Pb dating constrains their emplacement ages from ca. 2.53 to 2.47 Ga and metamorphic ages at ca. 2.46 Ga and 1.86–1.82 Ga. The ca. 2.5 Ga DTT gneisses have consistent Sr-Nd-Hf isotopic compositions with positive whole-rock ɛ Nd (t) (+1.0 to +5.1), zircon ε Hf (t) (0.0 to +6.2) values, and older two-stage Hf model ages of 2.7–3.0 Ga, indicating they are cogenetic and derived from the partial melting of preexisting mafic crust. The dioritic gneisses with elevated MgO (3.09–4.94 wt%) and compatible element compositions (e.g., Cr and Ni) originated from a mafic crustal source modified by mantle-derived melts. The high Sr/Y values (104–661) and positive Eu anomalies (Eu/Eu⁎ = 1.05–2.76) of trondjemitic gneisses are controlled by plagioclase accumulation. The granitic gneisses are slightly peraluminous with high K 2 O (5.00–6.29 wt%) and low FeOT and MgO contents, indicating they were formed from the remelting of preexisting tonalitic crusts. The DTT and granitic plutonic gneisses in the Huai'an Complex were likely derived from crust-mantle interaction and crustal reworking in a subduction-related arc setting. The diverse geochemistry of these ca. 2.5 Ga granitoids is significantly controlled by source compositions, magmatic mixture, and accumulation. The prominent ca. 2.5 Ga TTG and granitic magmatism in the NCC likely represent a dominated internal reworking of the continental arc crust with subordinate crustal growth involving a subduction environment. • ∼2.5 Ga granitoids originated from crustal reworking in a subduction arc setting. • High-Mg diorites originated from a mixture of mantle-derived magma and mafic crust. • The high-pressure signatures of trondhjemite result from plagioclase accumulation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Yudongzi BIFs were formed at ca. 2.8 Ga, and suffered two-stage metamorphism. • Yudongzi BIFs were formed on the back–arc basin setting. • Yudongzi complex combined to Yangtze Block later than Paleoproterozoic. The Yudongzi banded iron formations (BIFs) are widely spread in the Neoarchean Yudongzi Group of the Bikou Terrane, Central China. Their sedimentary and metamorphic ages, however, remain controversial, either their forming or reworking processes. In this contribution, we conducted an integrated study of zircon U-Pb-Hf isotope geochemistry, as well as mineral and bulk-rock geochemistry on the Heishan'gou iron deposit, the largest iron deposit of the Yudongzi BIFs, to constrain their formation and metamorphism ages, source of ore-forming material and tectonic setting. Mineral chemistry analysis indicates that the amphibolite, host-rock of the Heishan'gou deposit suffered amphibolite facies metamorphism. LA-ICP-MS U-Pb dating of zircon grains from orthometamorphic host-rocks suggests that the Heishan'gou deposit was formed at the early Neoarchean (2781 ± 43 Ma for amphibolite and 2776 ± 43 Ma for plagioclase-hornblende schist), and metamorphosed at ca. 2480 ± 26 Ma and 1818 ± 44 Ma, respectively. The low contents of aluminum, titanium and high field strength elements in BIFs suggest that they are detritus-free marine chemical precipitates. The rare earth elements (REE) and Y patterns of BIFs display seawater-like signatures with light REE depletion, and positive La and Y anomalies. Meanwhile, their positive Eu anomalies suggest that submarine hydrothermal fluid might also be involved in the precipitation of BIFs. Combined with zircon Hf isotope data and geochemical compositions of amphibolites, it is proposed that the Yudongzi BIFs should be formed at back-arc basin setting. Compared with the representative Archean continent nucleus of the Yangtze Block (Kongling Complex), the Yudongzi Complex experienced distinct crustal evolutionary history. It indicates that the Yudongzi Complex might represent the accretionary block combined to the Yangtze continental nucleus later than the Paleoproterozoic. [ABSTRACT FROM AUTHOR]

The hornblendite complexes hosted in the Guyang granite-greenstone terrane form part of the Neoarchean basement in the Western Block of the North China Craton. In this study, we focus on the largest one from this block, previously named the Guyang komatiite, and present results from lithological, geochronological and geochemical studies. The dominant lithology in the Guyang hornblendite complex is greenschist facies hornblendite, and can be divided into clinopyroxene hornblendite (∼75%) and olivine-orthopyroxene hornblendite (∼25%). The oldest calculated Re depletion model ages ( T RD ) of these hornblendites is of 2454 Ma, and the zircon U-Pb age of the wallrock is 2480 Ma, with single-stage depleted mantle Nd model ages T DM1 (Nd) varying from 2.61 to 2.88 Ga. These data suggest that the Guyang hornblendite complexes formed during Neoarchean-Paleoproterozoic time. The hornblendites show low SiO 2 , high MgO contents and are enriched in Cr, Ni, and LREE with negative Ce anomalies and depleted in Ti, Nb and Ta. Their 187 Os/ 188 Os ratios range from 0.11145 to 0.11279, with γOs (2.5Ga) varying from −3.9 to +1.4. Geochemically, the olivine-orthopyroxene hornblendite shows little variation with typical cumulate feature. In contrast, the clinopyroxene hornblendite shows a large range of chemical variation. In the CaO vs. MgO and CaO/Al 2 O 3 vs. MgO diagrams, the clinopyroxene hornblendite shows Opx fractionation trend. Combined with lithological information, we infer that the hornblendite magma was emplaced as a crystal mush, with orthopyroxene as cumulus phase. The Os and Nd isotope composition, negative Nb, Ta, Ce anomalies, and the relationships in Th/Yb–Nb/Yb diagram suggest that the Guyang hornblendites formed from a source mantle that was modified by subduction-related melts/fluids derived from a seawater-altered basaltic slab. Compared with typical Archean komatiites, the rocks of present study show significant differences in lithological and geochemical characteristics, and thus it cannot be named as komatiite. To explain these characteristics, we propose a geodynamic model involving ridge subduction and slab window mechanism to account for the formation of the Guyang hornblendite complex. [ABSTRACT FROM AUTHOR]

When modern-style plate tectonics started and operated on a specific old craton has been a key point involving the early Earth's evolution. In order to address this issue on the evolution of the Neoarchean North China Craton (NCC), we investigated a representative successive magmatic rock suite of tonalite-trondhjemite-granodiorite (TTG) and sanukitoid in the Datong-Huai'an Complex. Geochemically, TTG gneisses in the Datong-Huai'an Complex can be divided into high-pressure (HP) and low-pressure (LP) TTG rocks. The HP TTGs emplaced at ∼2538–2497 Ma and 2441 Ma, respectively. Geochemical data shows that they are characterized by steep rare earth element (REE) patterns, obvious negative Nb, Ta, Ti anomalies and positive δEu anomalies, high Sr/Y, Nb/Ta and (La/Yb) N ratios, and positive ɛ Hf (t) (+2.1 to +9.1) and δ18O values (avg. 5.5‰ to 6.0‰). Their protolith is interpreted as the consequence of partial melting of a subducted oceanic slab with garnet and minor rutile as residual phases. In contrast, the LP TTGs emplaced at ∼2518 Ma. They display flat REE patterns, slightly negative Nb, Ta, Ti anomalies and negative δEu anomalies, low Sr/Y, Nb/Ta and (La/Yb) N ratios, positive ɛ Hf (t) (+3.4 to +5.9) and high δ18O values (avg. 5.9‰ to 6.1‰). They were most likely generated by partial melting of the mafic lower crust with residual plagioclase and amphibolite in the source region. The sanukitoid rocks emplaced at 2517–2485 Ma and show high MgO, Cr and Ni concentrations but relatively low (La/Yb) N values, positive ɛ Hf (t) values (+1.5 to +5.4), and higher δ18O values (avg. 6.8‰ to 7.5‰), suggesting that they were originated from partial melting of the mantle peridotite that was previously modified by slab-derived or sediment-derived melts. Combined with previous petrological, geochronological and geochemical data, we propose that the Datong-Huai'an Complex recorded the prolonged magmatism through ca. 2.56 Ga to 2.44 Ga, which was characterized by the high-angle subduction of oceanic lithosphere, leading to the opening of a mantle wedge, slab rollback and back-arc extension. All these lines of evidence manifested that a modern-style plate tectonics regime started along the western margin of the NCC Eastern Block during the late Neoarchean, though the interior Eastern Block was still dominated by the mantle plume-induced crustal growth and vertical tectonism. • Coeval TTGs and sanukitoids were recognized in the Datong-Huai'an Complex. • They recorded the prolonged high-angle subduction with rollback and back-arc extension. • Modern-style plate tectonics started along the margin of NCC Eastern Block in late Neoarchean. [ABSTRACT FROM AUTHOR]

Subduction polarity reversal events following arc–continent, arc–arc or continent–continent collisions have been well-documented from Cenozoic, Mesozoic, and Paleozoic orogens, but not from the Archean. We here document a Neoarchean subduction reversal event after an arc–continent collision between the Eastern Block of the North China Craton (NCC) and the Fuping arc using field, geochemical and geochronological data. We focus our work on the Wangjiazhuang granite in the Zanhuang massif located along the eastern margin of the Central Orogenic Belt (COB) of the NCC, and a regional tectonic comparison with other granitic rocks with similar ages, geochemical and petrogenetic characteristics. The ca. 2.5 Ga A-type Wangjiazhuang granite intrudes the Neoarchean Zanhuang mélange belt and contains mafic and felsic inclusions. It has positive ε Nd (t) values (+ 0.12 to + 1.13) and T DM2 ages between 2784 Ma and 2869 Ma. This work shows clearly, from field structural relationships, geochemistry and geochronology, that the Wangjiazhuang granite formed after an arc–continent collision between the Eastern Block which is defined as a continental block and the Fuping arc, after a subduction polarity reversal event placed a new slab beneath the collisionally modified margin of the Eastern Block and converted it to an Andean-type margin. The subduction polarity reversal event at ca. 2.5 Ga resulted in melting of the enriched mantle. Meanwhile, the rising magma induced partial melting of the old and thickened TTG crust leading to the intrusion of ca. 2.5 Ga Wangjiazhuang granite into the Neoarchean Zanhuang mélange. There are other granitic rocks with similar ages and geochemical and petrogenetic features in the Central Orogenic Belt and Eastern Block of the North China Craton, suggesting that they formed in a similar tectonic setting as the circa 2.5 Ga granites across the Eastern Block. The Neoarchean subduction polarity reversal event and prior arc–continent collision provide strong evidence that plate tectonics was operating by the end of the Neoarchean. [ABSTRACT FROM AUTHOR]

Western Shandong Province is a typical area of the North China Craton (NCC) where Neoarchean plutonic and supracrustal rocks are widely distributed. Early studies documented that ∼2.7 Ga and ∼2.5 Ga magmato-tectono-thermal events are well developed in the area. Here we report SHRIMP U–Pb ages and Hf-in-zircon isotopic data from ten samples of different magmatic rock types including hornblendite, gneissic tonalite, gneissic trondhjemite and gneissic granite. Magmatic zircon grains have 207 Pb/ 206 Pb ages ranging from 2667 to 2598 Ma. Some rocks contain ∼2.5 Ga metamorphic rims and ∼2.7 Ga zircon cores. The magmatic zircon grains have ɛ Hf ( t ) values and Hf crustal model ages of −1.1 to +11.3 and 3.02–2.4 Ga, respectively. Combined with an earlier study, our main conclusions are that the middle Neoarchean rocks mainly occur together with early Neoarchean rocks in the northeastern portion of the central belt. Juvenile additions to continental crust and crustal recycling played important roles in the middle Neoarchean of western Shandong Province, and the entire Neoarchean tectonic evolution can be divided into middle to early Neoarchean (2.75–2.6 Ga) and late Neoarchean (2.6–2.5 Ga) events. [ABSTRACT FROM AUTHOR]

Abstract: As an important component of the Western Shandong Complex in the Eastern Block of the North China Craton, the Yishui Terrane consists of Neoarchean high-grade supracrustal rocks, granitoid gneisses and charnockites. LA-ICP-MS zircon U Pb dating and Hf isotopic analyses on these lithologies have been carried out and the results provide new insights into the Neoarchean crustal evolution of the Eastern Block of the North China Craton. New zircon dating results reveal that the magmatic precursors of the supracrustal metapelites and granitoid gneisses were generated at 2.54–2.53Ga and 2.57–2.55Ga, respectively, and the charnockites were emplaced contemporaneously around 2.56–2.53Ga. Single metamorphic zircon grains and overgrowth rims from these rocks document consistent metamorphic ages at ~2.50Ga, suggesting that the Yishui Terrane experienced a high-grade metamorphic event at the end of the Neoarchean. Detrital zircons from pelitic gneisses yield 207Pb/206Pb ages of 2.89–2.65Ga, with a major age peak at ~2.53Ga and a subordinate age peak at ~2.70Ga, implying that the sedimentary protoliths of the pelitic gneisses may have been sourced from ~2.53Ga rocks in the Yishui Terrane and ~2.70Ga rocks in the adjacent Luxi Granite-Greenstone Terrane. Hf isotopic compositions show that the Neoarchean magmatic zircons have positive εHf(t) values ranging from +1.4 to +7.8 and depleted mantle model ages of 2.92–2.60Ga with a prominent peak at 2.8–2.7Ga, suggesting that the Neoarchean crust was derived mainly from juvenile sources and partly from the recycling of old continental crust in the Yishui area. Combined with previous data from the adjacent Luxi Granite–Greenstone Terrane and other complexes in the Eastern Block, it is concluded that the Neoarchean was an important period of crust accretion in the Eastern Block of the North China Craton. [Copyright &y& Elsevier]

Abstract: At the end of the Neoarchean continental evolution, voluminous syenogranites were emplaced in the North China Craton, together with other magmatic rocks (trondhjemite–tonalite–granodiorite (TTG), monzogranite, diorite, gabbro). Syenogranites are widely distributed in Anshan-Benxi, Qinhuangdao and western Shandong, and also occur in southern Jilin, northern Liaoning, northwestern Hebei and central Henan. Based on geological relationships, degree of metamorphism, deformation and magmatic zircon ages, two phases of syenogranite magmatism are recognized. Rocks produced during the first phase show a gneissic texture and were formed between 2.53 and 2.52Ga and locally comprise abundant TTG. Rocks of the second phase cut late Neoarchean TTG and supracrustal rocks, display a massive structure, and mainly formed between 2.52 and 2.50Ga. All syenogranites share the same features in major element compositions, being high in SiO2 and low in CaO, total FeO, MgO, TiO2 and P2O5. However, they are different in trace and REE compositions and can be subdivided into three types. (1) Type 1 shows a large variation in total REE contents, low (La/Yb) n ratios, strong negative Eu*/Eu anomalies and Ba depletion; (2) Type 2 is similar to Type 1 but has higher (La/Yb) n ratios. (3) Type 3 shows a large variation in total REE and (La/Yb) n ratios and significantly do not show strongly negative Eu*/Eu anomalies and Ba depletion. Whole-rock Sm–Nd isotopic compositions show large variations in ɛ Nd(t) values and t DM(Nd) modal ages, ranging from −9.49 to −4.72 and 3.70 to 3.25Ga (Type 1), 0.55–1.03 and 2.77–2.71Ga (Type 2) and −2.35 to 1.23 and 2.93–2.66Ga (Type 3), respectively. Hf isotopic compositions of zircons from three samples have ɛ Hf(t) values and t DM1(Hf) ages of 0.7–7.2 and 2.84–2.56Ga (Type 1), 2.6–7.4 and 2.74–2.56Ga (Type 2) and 2.1–6.3 and 2.76–2.60Ga (Type 3). It is concluded that syenogranites were generated by melting of continental crust with different mean crustal residence ages, and most of them were emplaced during the second phase (2.52–2.50Ga) in an extensional tectonic regime. The formation of these voluminous syenogranites marks a tectono-magmatic event resulting in stabilization of the North China Craton at the end of the Neoarchean. [Copyright &y& Elsevier]

Abstract: Western Shandong Province is an important terrane in the eastern part of the North China Craton where 2.75–2.5Ga tectono-thermal events are well recognized. Supracrustal rocks, named the Taishan “Group”, experienced greenschist- to amphibolite-facies metamorphism and occur as lenses and strips in granitoids and are subdivided into the Yanlingguan, Shancaoyu and Liuhang “Formations”. The Yanlingguan “Formation” is mainly composed of amphibolite but also contains fine-grained biotite-hornblende gneiss, komatiitic rocks and schist. The Liuhang “Formation” is similar in rock association to the Yanlingguan “Formation” but contains more metasedimentary rocks. The Shancaoyu “Formation” is mainly composed of fine-grained biotite gneiss (leptynite) preserving bedding and is interlayered with schist. Its protoliths are mainly sedimentary rocks with some mafic to felsic volcano-sedimentary varieties. We undertook SHRIMP zircon dating on eighteen metasedimentary and volcanic samples, mainly from the Shancaoyu “Formation” and the upper part of the Liuhang “Formation”. Ages of detrital and volcanic zircons vary from 2.75 to 2.54Ga and 2.55 to 2.525Ga, respectively, and the age distribution patterns vary in different samples. We conclude that the Shancaoyu “Formation” and the upper part of the Liuhang “Formation” were deposited in the late Neoarchean (2.55–2.525Ga) and not in the early Neoarchean (2.8–2.7Ga) as thought before. Western Shandong is the only terrane in the North China Craton where both early and late Neoarchean supracrustal rocks have been identified. A magmatic arc model may be applied to explain the tectono-thermal evolution at the end of the Neoarchean. [Copyright &y& Elsevier]

Abstract: The Miyun Geopark is located in the northern part of the North China Craton and includes a variety of Archean granitoids and metamorphic rocks. SHRIMP zircon dating documents their emplacement ages at 2567–2508Ma, metamorphic events at ca. 2.50Ga, 2.44Ga, and 1.82Ga. Late Neoarchean basement rocks elsewhere in the North China Craton document a similar evolutionary history with intrusion of granitoid rocks commencing at ca. 2590Ma and reaching three peaks at about 2550, 2520, and 2500Ma; these rocks then underwent regional metamorphisms at ca. 2.50Ga, 2.44Ga, 1.92Ga, and 1.82Ga. Positive ε Hf(t) values of +1.7 to +7.6, with model ages younger than 3.0Ga, for magmatic zircons from these late Neoarchean intrusive rocks indicate that they are predominantly derived from juvenile crustal sources and suggest that significant crustal growth occurred in the northern North China Craton during the Neoarchean. The intrusive rocks in the Miyun area are part of an extensive province of late Neoarchean magmatism and appear to be related to mantle plume activity at this time. [Copyright &y& Elsevier]

Abstract: Neoarchean potassic meta-granites occurring in the Huai''an Complex within the north central part of the North China Craton (NCC) comprise leucocratic syenogranites, biotite monzogranites, and garnet-bearing syenogranites. High-pressure garnet–granulites occur as lenses, sheets or dismembered dikes with the granitoids. Here we present SHRIMP zircon U–Pb data from the leucocratic syenogranites which show an age of 2493±6Ma (MSWD=1), and LA-ICP-MS U–Pb data from the biotite-monzogranites and garnet–syenogranites, revealing their formation ages of 2437±10Ma (MSWD=2.0) and 1977–2003Ma, respectively. We also report metamorphic ages of ca. 1800Ma from zircons in the garnet–syenogranites. Geochemical studies show low MgO (0.5–0.06wt.%), Cr (6.19–0.53ppm) and Ni (27.66–2.01ppm) with varying SiO2 (62.3 to 76.8wt.%) contents, indicating their derivation from a crustal source. The leucosyenogranites exhibit elevated positive Eu anomalies with decreasing Sr, Th, U, and bulk REE concentrations, and Th/U ratio, whereas Rb and Ba values increase with decreasing Th/U ratio, indicating fluid–melt interaction. The leucosyenogranites have high Sr and Ba contents and Sr/Y and (La/Yb)N ratios and low Y and HREEs, with zircon εHf(t) values ranging from +1.7 to +5.8 and Hf model ages of 2.60–2.73Ga, reflecting their derivation by partial melting of overthickened juvenile lower crust of eclogitic composition, or an eclogitic mineral assemblage in the residue. Geochemical compositions of the biotite–monzogranites, with positive εNd(t) values (+2.3 to +2.5) and model ages <2.60Ga, indicate that they are evolved partial melts from a thickened juvenile crust of garnet amphibolite composition, or with garnet and amphiboles in the residue, followed by fractionation dominated by plagioclase precipitation. The garnet–syenogranites display variable contents of SiO2 (62.3–72.3wt.%), and relatively high Zr (491–1096ppm), Ga (23.5–31.2ppm), Zn (38–124ppm), Y (34.1–85.6ppm) and Nb (9.4–90.0ppm) abundances with 104 ×Ga/Al ratios of 3.1–4.2. They also possess low Sr (50–161ppm) concentrations and strong negative Eu anomalies. These features, integrated with Nd model ages of 2.46–2.50Ga and relatively constant negative εNd(t) values (−2.5 to −2.9) with increasing SiO2 contents, suggest A-type granitic affinities of intraplate extensional or rift setting with evolution of the magma from partial melts derived from Neoarchean tonalitic rocks. The distinct geochemical features and zircon saturation temperatures of the granitoids are indicative of high melting temperatures (900–1000°C) at relatively low pressures (6–10kbar). Based on previous works and our new data, we link the ca. 2500–2450Ma and 2000Ma magmatic events to a Neoarchean amalgamation of microblocks and Paleoproterozoic mobile belts. The metamorphic ages of 1800–1820Ma might reflect an amphibolite facies retrograde event. [Copyright &y& Elsevier]

Abstract: The evolution of the North China Craton (NCC) is well known for a marked 2.55–2.50Ga tectonothermal event. However, supracrustal and intrusive rocks of 2.75–2.70Ga are in fact widely distributed in the western Shandong Province, the most important area of Archaean basement in the eastern part of the NCC. This paper reports SHRIMP U–Pb dating and LA-ICPMS Hf isotopic composition of zircons from 2.75–2.70Ga supracrustal and trondhjemite–tonalite–granodiorite (TTG) rocks in that area. Three fine-grained (hornblende) biotite gneiss samples (known locally as leptynite, with meta-volcanic or volcanosedimentary rock protoliths) and five TTG samples have SHRIMP zircon U–Pb ages varying from 2.75 to 2.70Ga and 2.74 to 2.71Ga, respectively. Zircons from most of the samples have high positive ɛ Hf(t) values (+4.7 to +10.0) and t DM(Hf) ages (2.85–2.60Ga) similar to their zircon U–Pb ages. This indicates that the rocks represent largely juvenile crustal additions derived from depleted mantle only a short time before. However, some granitoids show ɛ Hf(t) zircon values of −13.6 to +5.1 and t DM(Hf) of 3.51–2.80Ga. Therefore, the strong 2.75–2.70Ga tectonothermal event in the western Shandong Province involved not only juvenile addition to the continental crust but also intracrustal recycling of older components. Combined with craton-wide data, it is shown that the NCC is similar to many other cratons around the world where tectonothermal events of ∼2.7Ga are well developed. However, the main difference is that in the NCC, superimposed ∼2.5Ga tectonothermal events were much stronger than in most other cratons. [Copyright &y& Elsevier]

The Wuhe complex (WC), exposed at the southeastern margin of the North China Craton (NCC), is an important constituent of the Eastern Block of the NCC. In order to better understand the Precambrian crustal composition and evolution of this region, a comprehensive investigation on zircon geochronology and Hf isotopes, as well as whole-rock geochemistry and Sr-Nd-Pb isotopes was conducted on alkaline ultrapotassic granitic gneisses from the WC at Mashan. These gneisses are considered as meta-igneous rocks based on geochemical and mineralogical criteria (with special reference to zircon cathodoluminescence images). They are characterized by modally abundant alkali feldspar (more than 60%) and quartz (more than 30%) while plagioclase is rare. Mafic minerals are sodic amphiboles such as arfvedsonite and eckermannite, aegirine and rare biotite. Minor constituents are rutile, muscovite, apatite and barite. Major elements geochemistry shows high SiO 2 (69.85%–74.51%) and K 2 O + Na 2 O (9.67%–12.17%) contents, high K 2 O/Na 2 O (7.41–22.53) ratios, and relatively low MgO (0.37%–0.87%) and CaO (0.10%–0.23%) contents. Trace elements geochemistry shows significant depletions of Nb, Y, Ce, Ga, and REE (rare earth elements) relative to anorogenic granites. These features suggest that the magmatic protoliths of the studied gneisses belong to ultrapotassic silica-saturated alkaline series from an extensional background, perhaps in a subduction-related rifting environment. As concerning isotope geochemistry, their 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios are 16.6297–17.1877, 15.4454–15.5066, and 36.6036–38.0304, respectively, and ε Nd (t) values vary from −1.7 to +9.1. Two samples yielded zircon 207Pb/206Pb ages of 2615 ± 4 Ma and 2617 ± 5 Ma, respectively, representing their precursor ages. The zircon igneous core domains exhibit oscillatory growth zoning with positive ε Hf (t) values (+2.5 − +6.6). These data, coupled with chondrite-normalized and primitive-mantle-normalized element patterns, suggest that the precursors of the studied granitic gneisses were mainly derived from a subduction-modified ultrapotassic syenitic parental magma, and may be considered as a particular group of A-type granites, involved in an important crustal growth and reworking event at ~2.6 Ga. These rocks experienced a granulite-facies metamorphic stage accompanied by partial melting, as testified by clinopyroxene + rutile + K-feldspar + spinel + quartz + apatite inclusions in zircon metamorphic domains which were dated at ~2.5 Ga. The occurrence of this metamorphic stage is also supported by the lower ΣREE contents, negative Eu anomalies, and high Ti-in-zircon temperatures (>800 °C) of metamorphic zircon mantles dated at ~2.5 Ga. Eventually, the studied rocks suffered a later ~1.85 Ga metamorphic overprinting, possibly related to the Paleoproterozoic collisional orogeny recorded in the region. • ~2.6 Ga alkaline ultrapotassic granitic gneisses in southeastern margin of the NCC • The gneisses' precursor was derived from a subduction-modified ultrapotassic magma. • The gneisses underwent two episodes of metamorphism at ~2.5 and ~1.85 Ga. • The tectonic transition from compression to extension during the late Neoarchean [ABSTRACT FROM AUTHOR]

[Display omitted] • Metavolcanic rocks of the Tonghua area were formed at ca. 2.60 and 2.52 Ga, and metamorphosed at 2.53–2.47 Ga. • The SJB and NLB experienced two episodes of crustal growth at ∼ 2.7 Ga and ∼ 2.6–2.5 Ga, and were reworked at 2.53–2.47 Ga. • The Northern Liaoning Block and Southern Jilin Block have different tectonic setting. • Metavolcanic rocks formed in a transitional inner-oceanic arc to active continental margin geodynamic setting. The Tonghua area is located on the northeastern edge of the Eastern Block of the North China Craton (NCC), and connects the Northern Liaoning Block (NLB) in the west and Southern Jilin Block (SJB) in the north. The greenstone sequences in this region are voluminous metavolcanic rocks, which mainly comprise amphibolite, pyroxene amphibolite, pyroxene/amphibole–plagioclase gneiss, and biotite–plagioclase gneiss. Here we present zircon cathodoluminescence images, U–Pb dates, and Lu–Hf isotope data, as well as whole-rock geochemical data for these rocks, in order to constrain the geodynamic evolution of the Neoarchean crust and mantle and define the crustal evolution process of the northeastern NCC. Zircons from these metavolcanic rocks can be divided into two groups, with one having a typical magmatic origin and the other a metamorphic recrystallization origin. Zircon U–Pb dating and Lu–Hf isotopic results show that the magmatic zircons have two peak ages, dated at ca. 2.60 Ga and ca. 2.52 Ga, with the former have ε Hf =+3.04 to + 9.24 and single-stage model ages (T DM) of 2.80–2.54 Ga, the younger group have ε Hf values of + 2.41 to + 7.05 and T DM values of 2.73–2.56 Ga. While the metamorphic zircons document consistent metamorphic ages at 2.47–2.53 Ga, suggesting a regional metamorphic event. Their framing into the regional background has allowed us to explore the complete Neoarchean tectonic-thermal event and further contrast the NLB and SJB in the chronology, as well as to reveal crustal growth (∼2.7 Ga, ∼2.6–2.5 Ga) and reworking (∼2.53–2.47 Ga) history in the Neoarchean. The geochemical data indicate that the rocks were divided into three types, with affinities to mid-ocean ridge basalt (N-MORB), island arc tholeiites (IATs), and continental arc basalts (CABs). Taking into account the arc-related magmatism and the distribution of ancient crystalline basement (≥2.7 Ga), it is proposed that a long-lived, active continental-margin setting may have evolved along the northeastern margin of the NCC during the late Neoarchean (∼2.5–2.6 Ga), which distinguishes the NLB and SJB. Moreover, the geochemical and Lu–Hf isotope mapping results also indicate that the NLB and SJB have different tectonic setting. We consider that the metavolcanic rocks from the Tonghua area are related to an arc–continent collision, and formed in a transitional inner-oceanic arc to active continental margin geodynamic setting during the late Neoarchean (2.6–2.5 Ga). [ABSTRACT FROM AUTHOR]

The North China Craton (NCC) consists of Neoarchean to Paleoproterozoic basement, with rare Eo-Paleoarchean crustal relicts. However, the Precambrian tectonothermal evolution of the Central Orogenic Belt (COB) of the NCC is still hotly debated. In this contribution, we present new results of field-based litho-structural analysis, Th-U-Pb geochronology of accessory minerals including zircon, titanite and monazite from paragneiss and marble in a passive margin sequence in the Zanhuang Massif of the COB. Field studies show that two generations of deformation events occurred in the Zanhuang Massif. The earlier deformation is widely distributed in the entire Zanhuang Massif and developed with a top-to-SE shear sense resulting in foliation of the micaschist, metavolcanic rock, marble and paragneiss. The latter deformation is locally occurred in the central Zanhuang Massif and developed with a top-to-SW shear sense represented by the faulting and folding events which are similar to the fold-and-thrust structures of accretionary wedge during the formation of Zanhuang mélange. Zircons from paragneiss yield single-peak age populations with mean ages of 2.52 and 2.51 Ga, and a metamorphic age of 1.84 Ga. Zircon ages from marble are divided into four groups including a main peak of 2.54 Ga, two older groups of 2.77–2.82 and 2.60–2.70 Ga, and a younger metamorphic age of 1.81 Ga. Titanites from paragneiss and marble yield mean metamorphic ages between 1.94 and 1.88 Ga, representing an earlier thermal event. Monazites from paragneiss yield an isochron age of 1.80 Ga, representing a later thermal event. Based on our new litho-structural observations and geochronological data, coupled with previous studies, we suggest that the paragneiss and marble from the marble-siliciclastic unit represent the passive margin sequence, and were mainly deposited at 2.51–2.50 Ga. In addition, the Zanhuang Massif has experienced two tectonothermal events at ca. 1.94–1.88 Ga and ca. 1.83–1.80 Ga, which are widely distributed in the entire NCC, but gradually become weaker from north to south. [ABSTRACT FROM AUTHOR]

• SJC experienced multiple magmatism of ~2.78, ~2.69 and ~2.55 Ga. • Neoarchean magma derived from episodic juvenile crust growth and crustal reworking. • Recycling of sediments was not intense or extensive in SJC during Neoarchean. • A bottom-up tectonic regime related to plume activity is favored for NCC in Neoarchean. Recent advances in high-precision in-situ analysis of zircon U-Pb-Hf-O isotopes have significantly improved our approach to studying the origin and evolution of Archean crust. This study presents high-precision in-situ zircon U-Pb-Hf-O isotopes for the Southern Jilin Complex (SJC) on the northeastern margin of the North China Craton (NCC) and explores the potential of such an integrated approach in understanding the Archean crust evolution and its tectonic implications. The SJC consists mainly of Archean granitoid gneisses hosting minor supracrustal rock xenoliths. Zircon U-Pb data from representative lithologies reveal three episodes of magmatism at ~2.78, ~2.69 and ~2.55 Ga, respectively. The former two granitoid magmatic events are recognized for the first time in NE NCC, while the latest one is widespread over the NCC. All metamorphic zircon domains document similar metamorphic ages of 2.51–2.48 Ga, consistent with the widespread metamorphism of ~2.50 Ga in the NCC. Most concordant magmatic zircons preserve "mantle-like" O isotopic signatures, indicating the magma sources were not contaminated by large amounts of high δ18O supracrustal sediments. Hf depleted mantle model ages of magmatic zircons display one predominant peak at 2.9–2.8 Ga and two subordinate peaks at 3.3–3.2 Ga and 2.7–2.6 Ga, indicating possible episodic crust-mantle differentiation in Southern Jilin. Integrated zircon U-Pb-O-Hf data from the SJC suggest that magma sources were mainly derived from multiple episodes of reworking of juvenile or ancient crust with mantle component addition, while recycling of sediments was trivial during the Neoarchean in this region. The spatial–temporal relations of magmatism, lack of supracrustal addition to magma sources, and other geological evidence from the NCC are in favor of a bottom-up geodynamic regime possibly related to plume activities, arguing against a widespread top-down mechanism involving modern-style subduction in the NCC during the Neoarchean. [ABSTRACT FROM AUTHOR]

• TTG, calc-alkaline mafic-intermediate rocks and A-type granite were produced coevally at 2.65–2.70 Ga in the Yangtze Craton. • These igneous rocks record subduction in the cratonic margin and extension in the interior. • Subduction style in the Neoarchean differs from modern one in both magmatism and geodynamics. • Both subducting crust and mantle wedge are partially melted in the Neoarchean subduction system. • The Neoarchean subduction is not continuous but intermittent. The Neoarchean is an important era during which plate tectonics began to operate widely on Earth. The style of plate tectonics in the Neoarchean should be different but poorly constrained. Here we report geochemical studies on felsic to mafic igneous rocks from the northern Yangtze Craton, which record a subduction at ca. 2.65–2.70 Ga with distinctive magmatic and geodynamic features from modern subduction system. The metaigneous rocks of felsic composition, trondhjemite gneisses (TTG), from the northern margin show high sodic contents, positive Eu anomalies, high (La/Yb)cn and Sr/Y ratios, low Yb and Y contents. The metaigneous rocks of mafic-intermediate composition from the northern margin are mainly calc-alkaline and show less fractionated REE patterns. They have similar zircon U-Pb ages of 2651 ± 30 Ma to 2703 ± 9 Ma, similar chondritic zircon ε Hf (t) values and whole-rock ε Nd (t) values of −1.6 to 3.4. Their zircon δ18O values are mostly 4.6–6.6‰, similar to or slightly higher than normal mantle values. Additionally, they all record a metamorphic event at ca. 2.47–2.50 Ga. The potassic granites from the interior are A-type in geochemistry and show similar zircon U-Pb ages and ε Hf (t) values to the metaigneous rocks in the northern margin but obviously lower zircon δ18O values from 3.6‰ to 5.4‰. The two types of rocks exhibit quartz δ18O values of 12.0–15.2‰ and 3.5–8.2‰, respectively. The trondhjemite gneisses and calc-alkaline metaigneous rocks were derived from partial melting of the subducted crust and the metasomatized mantle wedge, respectively. The A-type granites are the products of high temperature magmatism in an extensional setting in response to the contemporaneous subduction. This demonstrates the development of a subduction system in the northern Yangtze Craton during 2.65–2.70 Ga. The contemporaneous development of both slab-derived and mantle wedge-derived magmatism is suggested as a feature of the Neoarchean subduction system that is distinguished from the modern ones. The lack of TTG magmatism at 2.50–2.65 Ga but the reburst of TTG and metamorphism at 2.47–2.50 Ga imply that the subduction in the Neoarchean is intermittent. [ABSTRACT FROM AUTHOR]

• We document newly discovered ca. 2.5 Ga epidosites in the Zanhuang ophiolitic mélange of the North China Craton. • This work has important implications for understanding the seafloor hydrothermal activity of subduction zones in the Neoarchean. • Results show modern seafloor hydrothermal activity operated at ca. 2.5 Ga. Epidosites are suggested to form in up-flow zones located at the base of ore-forming oceanic hydrothermal systems, and are commonly preserved in ophiolitic sequences. However, occurrences of epidosites in Archean tectonic mélanges are rarely documented. In this study, we report the presence of late Neoarchean epidosites in the Zanhuang ophiolitic mélange in the North China Craton using meter-scale litho-structural and petrologic analysis, zircon U-Pb dating, major and trace element, and oxygen and strontium isotopic geochemistry. Field studies show that the epidosites are mainly preserved as the cores of meta -pillow lavas, and are distributed as blocks in different matrices within the tectonic mélange. The pillow rims are used as protolith to estimate the element mobility during the alteration process. The epidosites display strong depletion in Na 2 O (0.01–0.27 wt%), MgO (0.43–3.01 wt%), depletion in large ion lithophile elements (LILE) (e.g. Rb, Ba, Cs, U) and transition metals (e.g., Co, Sc, Cu, Ni, Zn), and show enrichment of CaO (13.35–21.0 wt%), Sr and Pb. The high field strength elements (HFSE) (e.g. Zr, Hf, Ta, Th) of epidosites are varied but rare earth elements (REE) are unchanged. The amphibolitic pillow rims are characterized by enrichment of LILE, flat heavy rare earth elements (HREE) patterns, and depletion in HFSE with negative Ti anomalies and positive Pb and Ba anomalies. Oxygen and strontium isotopic ratios of epidosites are 5.0–8.6‰ and 0.70284–0.70551, respectively, both of which are greater than those of fresh basalts. The major and trace elements, oxygen and strontium isotopic values and extensive element migration indicate that the protolith was altered by a submarine hydrothermal system in the absence of continental influence. Magmatic zircons from two samples of epidosites yield 207Pb/206Pb ages of 2512 ± 13 Ma (MSWD = 0.51) and 2542 ± 13 Ma (MSWD = 1.4), confirming that the epidosites were generated at ca. 2.51–2.54 Ga. Based on geochemical data and field observations, we suggest that the protolith of the epidosites formed in an arc-related tectonic setting during the late Neoarchean. This study shows that hydrothermal activity operating in the late Neoarchean was similar to that of the modern ocean floor. [ABSTRACT FROM AUTHOR]

• The eastern NCC has experienced an important episode of crustal growth at ca. 2.94-2.70 Ga, followed by the pervasive crustal reworking at ca. 2.70-2.55 Ga and regional metamorphism at ca. 2.55-2.45 Ga. • Geochemical features indicate that the Neoarchean Taishan TTG gneisses may be generated in a relative low-pressure condition. • The Neoarchean Taishan TTG gneisses were mostly derived from partial melting of juvenile crustal materials, which were equilibrated with a certain amount of amphibole and plagioclase and minor garnet in the residue. The Taishan Complex is located in the central part of the eastern North China Craton (NCC), and preserves extensive Neoarchean TTG gneisses and potassic granitoids. Their formation age, geochemical features and petrogenesis can provide important insights into understanding the crustal growth and reworking events involving in the evolution of the craton. Previous studies were mainly focused on geochronology of these Neoarchean rock assemblages, but lacked study on their petrogenesis and related tectonic regime. In this study, we carried out lithological, geochronological and geochemical analyses for the representative TTG gneisses of the Taishan Complex. U-Pb zircon age dating results reveal that the Taishan TTG gneisses were mainly emplaced at 2718-2548 Ma. Lu-Hf isotopic data show uniform positive zircon εHf(t) values (+2.2 to +6.6), with Hf model ages of 2949-2665 Ma, indicating that the TTG gneisses were mostly derived from juvenile crustal materials extracted from the depleted mantle during the Mesoarchean to Neoarchean. The δ18O values of zircons vary from +4.6 ‰ to +6.7 ‰, indicating that the source region was not significantly affected by the supracrustal materials. Geochemical data show that these TTG gneisses have high Na 2 O (3.81-4.83 wt%) and ratio of Zr/Sm (24-80), but show low Mg# (40-56), content of Sr (292-508 ppm), and ratios of Sr/Y (35.6-66.6) and Nb/Ta (10.1-15.9). These TTG gneisses were probably derived from partial melting of juvenile crustal materials under a relatively low-pressure environment, which were equilibrated with a certain amount of amphibole and plagioclase and minor garnet in the residue. It indicates that a large-scale magmatic underplating could be a most possible tectonic regime operating in this region during the Neoarchean. Our new results, combined with the available data from the adjacent areas, reveal a significant crustal growth event in the eastern NCC at ca. 2.94-2.70 Ga, which was followed by the pervasive crustal reworking event at ca. 2.70-2.55 Ga and regional metamorphism at ca. 2.55-2.45 Ga. [ABSTRACT FROM AUTHOR]

• The plutonic protoliths of the Huai'an gneisses were emplaced at 2.51–2.40 Ga. • The metamorphism was caused by continent-arc-continent collision at 1.86–1.80 Ga. • The Huai'an gneiss complex was formed in an intra-oceanic arc environment. • 2.8–2.6 Ga is a major period of juvenile crustal growth of Trans-North China Orogen. One of the major advancements in understanding the formation and evolution of the North China Craton was the recognition of a Himalayan-type collisional belt in the central part of the craton, called the Trans-North China Orogen (TNCO), along which two micro-continental blocks, named the Eastern Block and Western Block, joined together to form a coherent craton. However, controversy still remains about the pre-collisional tectonic setting and architectures of the TNCO. In this contribution, field-based zircon U–Pb and Lu-Hf isotopic investigations were carried out on the Huai'an gneisses from the Tianzhen-Xinpingbu area in the northern part of the TNCO. The Huai'an gneisses consist predominantly of tonalitic-trondhjemitic-granodioritic (TTG) gneisses with minor gabbroic, dioritic and granitic gneisses. Our zircon U-Pb results show that the plutonic protoliths of the Huai'an gneisses were emplaced at 2.51–2.40 Ga and experienced a granulite-facies metamorphic event at 1.86–1.80 Ga. The magmatic zircons of these samples yield ε Hf (t) values from +1.9 to +7.0 and T DM C ages of 2862–2619 Ma. These positive ε Hf (t) values, associated with the lack of old inherited zircons, suggest the derivation of their precursor magmas from a juvenile crust without contamination of old continental crust. The T DM C model ages indicate that 2.8–2.6 Ga is the best estimation of the mantle extraction time for the source rocks in the Huai'an gneisses, revealing a major period of juvenile crustal growth. Thus it can be inferred that the partial melting of subducted oceanic crust slab produced the magmas of the Huai'an gneisses, which subsequently interacted with overlying mantle wedge during the ascent, suggesting an intra-oceanic arc environment for the Huai'an gneiss complex. Taken together, the development of the Huai'an gneiss complex was involved in a subduction-related magmatic event in an intra-oceanic arc at ~2.5 Ga, followed by collision between the Eastern and Western blocks at ~1.85 Ga. [ABSTRACT FROM AUTHOR]

• This study documents the presence of a Neoarchean (ca. 2.5 Ga) pyroxenite-mélange in the Jianping Complex, NCC. • The pyroxenites in the Jianping Complex are cumulates derived from an arc-related lithospheric mantle source. • A 2.5 Ga subduction-accretion-collision event is proposed in the northern NCC. Mélanges are widespread in accretionary and collisional orogens at convergent plate margins. We document a Neoarchean mélange belt exposed in the Jianping Complex, North China Craton (NCC). The mélange belt contains a structurally chaotic tectonic mixture of paragneiss, metapelites mixed with exotic tectonic blocks of mafic and ultramafic rocks including pyroxenites, metagabbros, metadiabases, metabasalts, and TTG gneisses. The blocks have formation ages of ca. 2.53–2.51 Ga and all units in the mélange have been intruded by undeformed pegmatite dykes (ca. 2.49 Ga). Geochemical studies show that the pyroxenites in the mélange have high contents of MgO (15.84–20.87%), Mg# (68–80), Ni (211–446 ppm) and Cr (963–2491 ppm). They are characterized by slightly negative Eu anomalies, enrichment in light rare earth elements (LREE) and pronounced negative high field strength elements (HFSE) anomalies on chondrite- and primitive mantle- normalized diagrams. We suggest that the pyroxenites are cumulates derived from an arc-related lithospheric mantle source. The pyroxenites in the mélange are suggested to have formed in a subduction-related fore-arc environment whose mantle source was metasomatized by fluids derived from the subducted slab. The recognition of the Neoarchean Jianping pyroxenite-mélange and regional tectonic analysis of the NCC indicate that the mélange belt in the Jianping Complex is one segment of a 2.5 Ga suture zone that crosses the NCC, stitching a forearc segment of an oceanic arc terrane in the Central Orogenic Belt (COB) with the Eastern Block. The Jianping pyroxenite-mélange is therefore correlative with the Zunhua, Zanhuang, and Dengfeng mélanges in more southern segments of the Central Orogenic Belt, defining a Neoarchean suture that extends for approximately 1600 km across the craton. The geochemistry of the arc-derived magmas, and the tectonic association with a subduction-related mélange is similar in petrology, chemistry, structural style, and size to modern-day forearc settings, negating any calls for non-plate tectonic settings for arc-like magmas in the Archean. [ABSTRACT FROM AUTHOR]

• The felsic igneous rocks in the Lüliang complex were formed at 2.56–2.50 Ga. • The TTG gneisses and felsic volcanics were produced by partial melting of the moderately enriched arc crust. • The high-K granites were produced by partial melting of the arc crust similar to modern IAB. • Both 2.8–2.7 Ga and 2.6–2.5 Ga magmatic events were related to oceanic subduction. The North China Craton experienced two phases of tectonothermal events at ca. 2.8–2.7 Ga and ca. 2.6–2.5 Ga, respectively. Although 2.6–2.5 Ga granitic gneisses and metavolcano-sedimentary sequences are widespread in the craton, the major stage of crustal growth has been determined to occur at 2.8–2.7 Ga in terms of whole-rock Sm-Nd and zircon Lu-Hf isotope studies. It has been intriguing how the vast 2.8–2.7 Ga juvenile mafic crust would have differentiated into the 2.6–2.5 Ga felsic crust. This issue is addressed in the present study by investigating zircon U-Pb ages and Lu-Hf isotopes as well as whole-rock major-trace elements and Sm-Nd isotopes in Neoarchean felsic igneous rocks from the Yunzhongshan area in the central part of the North China Craton. Zircon U-Pb dating of felsic volcanics, TTG gneisses and high-K granites yields three groups of crystallization ages at 2562–2508 Ma, 2537–2504 Ma and 2518–2508 Ma, respectively, consistent with ages for mafic volcanics in the target area. Zircon Lu-Hf and whole-rock Sm-Nd isotope data indicate that all these rocks were ultimately originated from the ca. 2.8–2.7 Ga juvenile mafic crust. The felsic volcanics are subdivided into low-Si and high-Si suites. The low-Si rocks have higher MgO and FeO contents and contain abundant 2.8–2.7 Ga relict zircons with an age peak of 2.72 Ga, and were produced by partial melting of ~2.72 Ga TTG at ~730 to 750 °C. The high-Si volcanics were derived from partial melting of mafic restites after extraction of the ~2.72 Ga TTG, with significant amounts of garnet and amphibole, but no or rare plagioclase as residual phases, corresponding to a melting pressure at ~15 kbar. The TTG gneisses were produced by partial melting of ~2.8 to 2.7 Ga garnet amphibolites at ~10 to 15 kbar with variable amounts of garnet, amphibole and plagioclase in the residue. The high-K granites were produced by partial melting of ~2.8 to 2.7 Ga medium-high K mafic rocks at pressures of <10 to 12 kbar with a considerable amount of plagioclase in the residue. The TTG rocks and high-Si volcanics require a subduction origin to account for their enrichment in LILE, so that they were mostly likely derived from partial melting of the older arc crust with moderate enrichment in LILE and LREE. By contrast, the ultimate sources of the high-K granites would be the ~2.8 to 2.7 Ga medium-high K basalts, which have lower Zr/Sm ratios than the TTG gneisses and felsic volcanics, and even lower than the bulk continental crust, but consistent with modern island arc basalts. It is possible that the 2.8–2.7 Ga magmatism was subduction-related, with a compositional change of the mafic arc crust from relatively sodic to more potassic at around 2.7 Ga. This may be caused by accretion of the ancient oceanic arc onto the ancient continental margin. It was followed by both growth of the juvenile crust and reworking of the older arc crust in the late Neoarchean. Such series of magmatic processes can account for the voluminous generation of the 2.56–2.50 Ga felsic and mafic igneous rocks in the central part of the North China Craton. Taken together, both growth and reworking of the juvenile crust were realized through accretionary and rifting orogeneses, marking the operation of plate tectonics in the Neoarchean. [ABSTRACT FROM AUTHOR]

• The Dengfeng BIFs belong to Algoma-type BIFs. • They formed at ~2.53–2.51 Ga, consistent with peak ages of BIFs of the NCC. • They precipitated from a mixture of seawater and minor high-T hydrothermal fluids and crust-derived fluxes. • They deposited in an anoxic submarine environment in the late Neoarchean. Banded iron formations (BIFs) are important for understanding the composition and redox condition of paleo-oceans, as well as the evolution of the Precambrian crust. The Neoarchean Dengfeng greenstone belt (ca. 2.54–2.50 Ga) in the southern North China Craton (NCC) consists of metamorphosed igneous and sedimentary assemblages including some BIFs. Here, we present mineralogical, geochronological, geochemical and Sm–Nd isotopic data of the Dengfeng BIFs for the first time to constrain their age, origins and source characteristics, and then discuss their paleo-environmental implications. The BIFs are mainly associated with metabasaltic rocks and quartz-rich schists, and can be classified as Algoma-type BIFs. Zircon U-Pb dating of quartz-rich schists interbedded with the BIFs, coupled with ages of wall-rock metabasites, demonstrate that the Dengfeng BIFs formed at ~2.53–2.51 Ga. Most BIF samples have high contents of SiO 2 and Fe 2 O 3 T, and extremely low contents of Al 2 O 3 , TiO 2, and high-field strength elements (e.g., Zr, Hf, Th, U), indicating that they are detrital-free deposits. In the Post-Archean Australia Shale normalized multi-element diagram, the detritus-free BIF samples are characterized by depleted light rare earth elements, positive La and Y anomalies, and suprachondritic Y/Ho ratios, resembling geochemical features of modern seawater. The absence of negative Ce anomaly indicates an anoxic condition. Positive Eu anomalies and relatively high concentrations of transition metal elements suggest that high-temperature hydrothermal fluids contributed to the source of BIFs. Isotopically, all BIF samples have positive ε Nd (t) values (+0.12 to + 4.53), consistent with the range of those (+0.10 to + 4.31) of ca. 2.66–2.50 Ga Dengfeng metabasites and TTG gneisses, suggesting input of possible juvenile crustal fluxes. The elemental and isotopic characteristics of the Dengfeng BIFs collectively suggest that they precipitated from anoxic seawater with various input of hydrothermal fluids and oceanic crust-derived fluxes. [ABSTRACT FROM AUTHOR]