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The Neoarchean basement rocks of the Qixingtai region in the northwest of western Shandong, eastern North China Craton are divided into western and eastern domains, separated by a ductile shear zone. The western domain is mainly composed of early Neoarchean tonalitic and supracrustal rocks, and the eastern domain is composed of late Neoarchean crustally‐derived granite with diverse early Neoarchean enclaves up to several kilometres long of supracrustal and gneissic TTG‐diorite rocks. This study reports an integrated field, whole‐rock geochemistry and zircon U–Pb‐Hf study on the granites and their enclaves in the eastern domain. The supracrustal enclaves are mainly composed of meta‐basaltic and meta‐ultramafic rocks and are the same in lithological association and formation time as the 2,750–2,700 Ma Liuhang "Formation" in the western area. The TTG‐diorite enclaves can be divided into early and late groups. Magmatic zircons from early TTG‐diorite samples have U–Pb ages of 2,731 ± 17 to 2,748 ± 13 Ma and εHf(t) values of +2.7 to +9.5, whereas trondhjemite samples of the late group have U–Pb zircon ages of 2,588 ± 18 to 2,606 ± 12 Ma and εHf(t) values of +0.6 to +6.5. The Hf isotopic signatures on magmatic zircon from the >2,700 Ma diorite‐tonalites indicate that they are predominantly juvenile crustal additions, probably with minor involvement of older crust in their genesis, as given by tDM (Hf) ages ranging back to 2.92 Ga. The eastern granites range from monzogranite to syenogranite in composition and commonly have negative Eu anomalies, indicating residual plagioclase in the source region. Magmatic zircons from two granite samples have U–Pb ages of 2,516 ± 24 and 2,527 ± 18 Ma and εHf(t) values of +1.0 to +7.0. A fine‐grained syenogranite dyke contains inherited early Neoarchean zircons with εHf(t) values of +1.6 to +7.4. The isotopic signatures of the late Neoarchean granites that dominate the eastern domain show that they were derived from partial melting recycling of older continental crust recognized in the region – early Neoarchean rocks formed as a result of juvenile crustal additions. This is a common signature for late Archean crustal evolution throughout much of the North China Craton, and is the hallmark of some other Archean terranes, such as the Dharwar Craton of south India. The geodynamic explanations for the formation globally of vast amounts of crustally‐derived late Neoarchean granite are discussed. [ABSTRACT FROM AUTHOR]

Abundant mafic‐ultramafic blocks and dikes occur in the area north of Zunhua City, eastern Hebei Province, and were previously suggested to be part of a late Archean ophiolitic assemblage. We employed SHRIMP zircon dating and a geochemical study on these mafic and surrounding rocks to test the ophiolite hypothesis. The SHRIMP data suggest that three metagabbro samples were metamorphosed at ∼1.8 Ga. Numerous ∼2.5 Ga zircons display strong oscillatory zoning, characteristic of zircons from granitoid rocks but not from gabbro, so we suggest that these are xenocrystic grains. The age of these xenocrystic zircons and their metamorphic rims suggests that these mafic blocks formed in Paleoproterozoic. The surrounding gneiss of intermediate composition also contains 2.5 Ga zircons with oscillatory zoning and 1.8 Ga metamorphic rims. Fractionated REE patterns and Nb, Ta, Zr, Hf negative anomalies to variable extent were observed in the mafic blocks and surrounding rocks, also supporting a significant difference in the chemistry of ophiolitic rocks. Our data suggest that many mafic blocks in northern Zunhua are not part of a late Archean ophiolite complex but part of a tectonically dismembered Paleoproterozoic intrusive gabbro complex. This study shows that late Paleoproterozoic metamorphism occurred in the western part of eastern Hebei Province. [ABSTRACT FROM AUTHOR]

Eastern Shandong is one of the important early Precambrian areas in the North China Craton, where extensive 2.5, 2.7 and 2.9 Ga magmatic activities have been identified, followed by very strong late Neoarchean and Paleoproterozoic tectono-thermal events. We carried out SHRIMP zircon dating, Hf-in-zircon isotope analysis and a whole-rock geochemical study on ca. 2.9 Ga Mesoarchean magmatic rocks. These include gneissic diorite, gneissic quartz diorite, gneissic tonalite and gneissic high-Si trondhjemite and were identified in five new areas. All these rocks contain ca. 2.5 Ga metamorphic zircons. The dioritic and tonalitic rocks are enriched in large ion lithosphile (LIL) elements (K, Rb, Ba) and depleted in Nb and P with moderate to highly fractionated REE patterns, similar in chemical compositions to Archean TTG rocks worldwide. The high-Si trondhjemites are characterized by very high SiO 2 and very low FeOt + MgO. The magmatic zircon grains from all these rocks are similar in their Hf isotopic compositions and have ɛ Hf ( t ) values ranging from + 1.3 to +9.9. Combined with previous work, our main conclusions are: (1) eastern Shandong underwent a major magmatic event at ca. 2.9 Ga; (2) diorites and tonalites formed by melting of thickened lower crust or the root of an oceanic plateau, whereas the high-Si trondhjemites were derived from melting of intermediate to felsic rocks; (3) the Mesoarchean (ca. 2.9 Ga) was a major period of juvenile crustal addition from the depleted mantle, earlier than the major crustal growth period at 2.7–2.8 Ga in the North China Craton; (4) the 2.7–2.9 Ga rocks underwent strong metamorphism at ca. 2.5 Ga, probably as a result of magmatic underplating. [ABSTRACT FROM AUTHOR]

The western Shandong Province (WSP) is one of the typical Neoarchaean granite-greenstone belts in the Eastern Block of the North China Craton (NCC) and is an important region to investigate the early Precambrian evolutionary history of the NCC. The Taishan association, consisting of a ~2.7 Ga komatiite-tholeiite sequence and a ~2.5 Ga felsic volcano-sedimentary sequence, is the major lithological assemblage in the WSP. In the Qixingtai area, the felsic volcano-sedimentary sequence, partly subjected to anatexis, is composed of hornblende gneiss, voluminous fine-grained biotite gneiss and biotite plagioclase gneiss. SHRIMP zircon dating shows that the protolith of the biotite plagioclase gneiss formed after ca. 2.53 Ga. The tonalite intrusion into the volcanic protoliths of the fine-grained biotite gneiss and biotite plagioclase gneiss occurred at 2.52 Ga. Our age data constrain the time of formation of the felsic volcano-sedimentary sequence in the Taishan area as 2.53-2.52 Ga. The majority of zircons from the felsic volcano-sedimentary rocks have intermediate εHf(t) values (−1.2 to +2.1). The whole rock Nd isotopes of the Taishan felsic volcano-sedimentary rocks yield the εNd(t = 2522 Ma) values of +2.6 to −1.8 and TDM2 ages 3.03-2.68 Ga. These values indicate the pre-existing crust was reworked at the end of the Neoarchaean (~2.5 Ga). The Taishan felsic volcano-sedimentary rocks are rhyodacite-dacite and andesite in composition. These rocks and the tonalite display similar high SiO2 (65-72 wt.%) and low MgO (1-2 wt.%) content. In contrast, the minor andesites in the area have lower SiO2 (61-62 wt.%) and higher MgO (5.3-6.3 wt.%), suggesting more mantle contribution during their petrogenesis. However, the Mg-rich andesites have identical rare earth element and multi-element patterns with the rhyodacite-dacites and distinguish them from the Taishan sanukitoids. We suggest that the 2.53-2.52 Ga felsic volcanics of the Taishan association are the products of partial melting of a subducted oceanic crust. The andesites were produced by minor modification of the ascending tonalite-trondhjemite-granodiorite-type magma by the mantle wedge. Our study indicates that (1) the tectonic regime of the WSP greenstone belt was dominated by an arc-subduction system at ~2.52 Ga and (2) the 2.53-2.52 Ga felsic volcano-sedimentary rocks and intrusive tonalite are the products of crustal reworking. The felsic volcano-sedimentary sequence of the Taishan association and other ~2.5 Ga arc-like assemblages in the NCC provide important clues to understand the nature of the tectonothermal events at the end of the Neoarchaean. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The North China Craton (NCC) is the largest craton on the Chinese Mainland, with 3.8–3.0 Ga rocks occurring mainly in three areas, namely: Anshan-Benxi (Anben), eastern Hebei, and Xinyang. In addition, 3.0 Ga and 3.1 Ga TTG (tonalite-trondhjemite-granodiorite) rocks have also been identified in north Liaoning and the Bohai Bay Basin, respectively. Detrital and xenocrystic zircons dated at 4.1–3.1 Ga occur more widely in the craton. In Anben, >3.3 Ga rocks are mainly distributed in six complexes, whereas in eastern Hebei, 3.8 Ga TTG rocks and 4.0–3.9 Ga detrital zircons have recently been discovered. Anben is similar to eastern Hebei in terms of the Archean zircon age records, but >3.3 Ga TTG rocks are different in both rock-type and composition. The recent identification of 3.8 Ga granitic xenoliths in young volcanic rock at Xinyang indicates the existence of Eoarchean rocks in the deep crust of the craton. Taking the NCC as a whole, the most significant zircon-forming magmatic events occurred at 3.8 Ga, 3.7–3.65 Ga, 3.45 Ga, 3.3 Ga and 3.1 Ga. The >3.0 Ga TTG rocks are mainly trondhjemite, with their low Sr/Y and La/Yb ratios indicating formation under low- to medium-pressure conditions. These are different from 3.0 to 2.5 Ga TTG rocks in the NCC and 3.8–3.0 Ga TTG rocks in southern West Greenland, which are dominated by tonalite, with some having high Sr/Y and La/Yb ratios. The >3.0 Ga rocks have large variations in whole-rock ε Nd (t) and in-situ zircon ε Hf (t), with many showing negative values. Zircons have δ18O values mainly between 5.0 and 7.0‰, consistent with Hadean and Archean magmatic zircon data worldwide. The diversity of Eoarchean granitoid magmatism across the craton indicates that continental evolution on Earth at that time already displayed complexity and maturity. It is further considered that the NCC may contain several different ancient continental nuclei with long-term formation and evolutionary histories back to the Hadean. [ABSTRACT FROM AUTHOR]

Mesoarchean and older potassic granites are important indicators of recycling of ancient continental crust early in Earth's history. This study of integrated whole rock and zircon geochemistry and geochronology reports the age and identification of the source materials of the > 200 km 2 Mesoarchean Tiejiashan-Gongchangling granite in the Anshan-Benxi area, North China Craton, the largest pre-Neoarchean granite domain in the craton. SHRIMP U-Pb zircon dating on 15 samples indicates the magmatic crystallization of the granites between 2.95 and 3.0 Ga and reveals a superimposed tectonothermal event at ~ 2.91 Ga. The granites are characterized by high SiO 2 and K 2 O, low CaO, FeOt, MgO and TiO 2 with peraluminuous features. They show large variations in (La/Yb) n and strong negative Eu and Ba anomalies and Nb, P and Ti depletions. Whole rock Nd and magmatic zircon Hf isotopic compositions show large variations, but with most having ε Nd (t) and ε Hf (t) values < 0, with t DM (Nd) and t DM (Hf) values varying from 3.3 to 3.9 Ga and 3.3 to 4.0 Ga, respectively. Magmatic zircons without very strong lead loss (discordance ≤ 20%) have δ 18 O values of + 3.14 to + 8.39. 3.3–3.7 Ga xenocrystic zircons occur in some samples. The granite formed as a result of recycling of Paleo- to Eoarchean continental material in an intracontinental environment, with little if any contribution from Mesoarchean mantle sources. The sources could be predominantly unaltered ancient gneisses, together with yet to be identified Paleo- to Eoarchean materials affected by early low temperature alteration (weathered rocks or clastic sediment). [ABSTRACT FROM AUTHOR]

[Display omitted] • A new complex, named as the Hujiamiao Complex, was discovered in the Anshan area, NCC. • Trondhjemitic rocks of different ages from 3.79 to 3.11 Ga have been identified. • It is the first time in Anshan to identify trondhjemitic rocks with relatively high (La/Yb) n ratios. • Magmatic zircons have ε Hf (t) of −12.3 to 1.6, t DM (Hf) and t CC (Hf) ages of 4.1 to 3.6 Ga and 4.3 to 3.7 Ga. • All the Anshan 3.8–3.3 Ga complexes are the relics of the same larger complex in the area. Anshan is located in the northeastern North China Craton and has a long-term geological history back to 3.8 Ga. Four complexes with ages of 3.8–3.1 Ga have been identified previously, namely the Baijiafen, Dongshan, Shengousi and Guodishan complexes. Being similar to the neighbouring Beijiafen Complex, the newly-discovered Hujiamiao Complex extends in a northwest-southeast direction and shows tectonic contacts on one side with the Chengtaigou granite and on the other with the Chengtaigou supracrustal rocks. In the Hujiamiao Complex, trondhjemitic rocks of 3789 Ma, 3786 Ma, 3698 Ma, 3617 Ma, 3566 Ma, 3504 Ma and 3106 Ma have been identified. More work is required to establish if a gabbro also has a formation age of 3.8 Ga. The trondhjemitic rocks show similar compositional features in being high in SiO 2 (72.37–76.71 %) and Na 2 O (5.00–6.47 %) and low in K 2 O (0.60–1.95 %), ∑REE contents (32.83–91.83 ppm) and (La/Yb) n ratios (11.09–48.64). They have whole-rock ε Nd (t) values of 0.35–4.43, t DM (Nd) of 3.74–3.46 Ga and t CC (Nd) ages of 3.74–3.43 Ga, and in situ magmatic zircon ε Hf (t) values of −12.3 to 1.56, t DM (Hf) ages of 4.2 to 3.5 Ga and t CC (Hf) ages of 4.6 to 3.7 Ga. Combined with previous work, it is concluded that all the Anshan area 3.8–3.3 Ga complexes are the relics of a larger complex which was once more widely distributed in the Anshan area. The trondhjemitic rather than tonalitic character of the Anshan Eoarchean rocks shows diversity in the formation and evolution of the earliest continental crust with a range of T/P for crustal anatexis. [ABSTRACT FROM AUTHOR]

We report zircon ages, Hf-in-zircon isotopes as well as whole-rock geochemistry and Hf–Nd isotopic systematics for Palaeoarchaean grey gneisses of the Ancient Gneiss Complex of Swaziland, the oldest components of the Kaapvaal craton, southern Africa. The Hf-in-zircon isotopic compositions in these compositionally heterogeneous, multicomponent, migmatitic gneisses are highly variable, even in the oldest zircons dating back to 3.66 Ga, suggesting growth of zircon from melts representing a mix of juvenile and anatectic material derived from differentiated continental crust of Eoarchean to late Hadean age. In contrast, the initial Nd and Hf whole-rock isotopic compositions are frequently not in agreement with the Hf-in-zircon data that mostly show approximately chondritic initial values for Nd and strongly radiogenic initial values for Hf. We consider it likely that both the Lu–Hf and Sm–Nd whole-rock isotopic systems were disturbed and partly reset during later episodes of partial melting and crustal reworking, most likely during a pervasive 3.2 Ga tectono-metamorphic event. Primitive mantle-normalized trace element patterns show the variable influence of residual plagioclase and garnet in the sources as well as high contents of strongly incompatible elements. In conjunction with the Hf-in-zircon isotopic data the trace element contents are best explained by the incorporation of older continental crustal material into the sources of the grey gneisses. Our data support evidence from other Palaeoarchean terranes that crustal recycling, as seen in even the oldest crustal components, played an important role in early continental evolution. Rocks previously classified as a subduction-related tonalite–trondhjemite–granodiorite suite are complex, and their chemistry alone cannot be used to reconstruct tectonic settings. [ABSTRACT FROM AUTHOR]

Western Shandong is the only area in the North China Craton where abundant supracrustal rocks of the early and late Neoarchean are developed. This study presents an integrated geological investigations, whole-rock geochemistry and SHRIMP U Pb zircon dating investigation of the supracrustal rocks at Yanlingguang, one of the most typical areas of Neoarchean supracrustal rocks in western Shandong. The original Yanlingguan 'formation' is now subdivided into three belts: the Northeastern, Central and Southwestern belts, which are all in tectonic contact. The Northeastern and Southwestern belts are mainly composed of meta-komatiitic and basaltic rocks. Four granitic dykes intruding these belts have magmatic zircon ages of 2731–2530 Ma, supporting the conclusion that the supracrustal rocks were formed in the early Neoarchean. Meta-basalt with pillow structures has been identified in several locations, with the largest being ~35 m in thickness. The meta-komatiitic rocks are Al-undepleted komatiites and have ∑REE and (La/Yb) n of 2.30–26.21 ppm and 0.29–2.35, respectively, whereas the meta-basaltic rocks have ∑REE and (La/Yb) n of 16.45–53.26 ppm and 0.67–1.78, respectively, and ε Nd (t) values of 3.36–4.76, being similar to N-MORB. Eleven samples of meta-sedimentary rocks (including meta-sandstones-siltstones and meta-conglomerates) from the Central Belt have zircon U Pb ages extending from 2760 to 2520 Ma, providing evidence for the first time that they were deposited during the late Neoarchean, rather than the early Neoarchean as previously thought. The meta-sandstones-siltstones show large variations in major element contents, but have low ∑REE (49.17–102.30 ppm) and (La/Yb) n (1.53–7.00) ratios, with negligible to weakly negative or positive Eu anomalies (Eu/Eu* = 0.60–1.17), and record ε Nd (t) values of 0.96–3.21. Combined with regional geological investigations, we conclude that the early Neoarchean supracrustal rocks were formed in an oceanic environment. It is also suggested that the sandstones-siltstones of the late Neoarchean were derived from the early Neoarchean basement, and that the conglomerates were derived from two separate source regions; one of early, and the other of late Neoarchean age. The identification of basal conglomerates is consistent with the arc model established in early studies. We suggest that the criteria employed in this study can be used for determining whether or not an Archean greenstone belt is of oceanic affinity. • Yanlingguang in western Shandong contains three greenstone belts that differ in age. • The Northwestern and Southwestern belts are early Neoarchean. • The Central belt is late Neoarchean. • Early Neoarchean ultramafic and mafic rocks formed at 2.75 Ga in an oceanic setting. • Late Neoarchean metasedimentary rocks formed at 2.52 Ga in an island arc setting. [ABSTRACT FROM AUTHOR]

The accretion and recycling of Archean-Paleoproterozoic continental crust is the key to understanding the formation and evolution of early continental crust. Early Precambrian metamorphic basement is well developed in the Aktashtagh area, southeastern margin of the Tarim Craton, northwestern China. We report zircon SHRIMP U Pb dating, LA-MC-ICP-MS Lu Hf isotopic analysis and whole-rock geochemical analysis on 16 samples (mainly TTG, tonalite-trondhjemite-granodiorite) from Aktashtagh. Multiple episodes of early Precambrain magmatism, including 3.72 Ga, 3.63 Ga, 3.10 Ga, 2.83–2.69 Ga, 2.55–2.50 Ga, 2.05–2.02 Ga and 1.93–1.82 Ga events, have been identified in the Aktashtagh region. The most intense magmatism occurred in the late Mesoarchean to early Neoarchean. Significantly, 3.63 Ga and 3.10 Ga TTG rocks are identified, together with more extensive 2.8–2.7 Ga and ∼ 2.5 Ga TTG rocks. The TTG suites are dominated by tonalitic, with some trondhjemitic and grandioritic rocks. They show large variations in REE contents, are mainly distributed in the high- and medium-pressure fields in the Sr/Y-Y and La/Yb-Yb diagrams, and the 2.7 Ga TTG rocks commonly show higher and more variable Sr/Y and La/Yb ratios. The 3.63–3.10 Ga TTG rocks have magmatic zircon ε Hf (t) values of −3.9 to +3.1 and t DM1 (Hf) model ages of 3.9–3.6 Ga, whereas the ∼2.7–2.51 Ga TTG rocks have magmatic zircon ε Hf (t) values of −13.4 to +2.1 and t DM1 (Hf) model ages of 3.3–3.0 Ga. The ∼2.7 to ∼2.0 Ga meta-gabbroic-dioritic rocks have magmatic zircon ε Hf (t) values of −19.7 to +0.6 and t DM1 (Hf) model ages of 3.2–2.4 Ga. Metamorphic zircon ages of 3.56 Ga, 2.75–2.73 Ga, 2.53–2.51 Ga, 2.03–1.96 Ga and ∼ 1.85 Ga are also recorded, whereas ∼2.83 Ga, 2.53–2.40 Ga, 2.05–2.02 Ga and 1.86–1.83 Ga crustally-derived K-rich granites are identified, with the most important occurring in the late Neoarchean and late Paleoproterozoic. In this regard, the Tarim Craton is similar to the North China Craton in its early Precambrian geological evolution. The main difference is that the Paleoproterozoic tectonothermal event in the Tarim Craton started as early as 2.00 Ga, whereas in the North China Craton it occurred between 1.95 and 1.80 Ga. • Aktashtagh of the southeastern Tarim Craton has multiple episodes of magmatism from 3.72 to 1.82 Ga. • TTG show large Sr/Y-Y and La/Yb-Yb variations and magmatic zircons have ε Hf (t) of −15.2 to +3.1. • There were multiple Paleoarchaean to Paleoproterozoic events leading to crustal recycling. • The early Precambrian geological records are similar to those in the North China Craton. • The Tarim and North China cratons may be different portions of a larger craton. [ABSTRACT FROM AUTHOR]

Abstract: Through detailed studies we have delineated a suite of banded TTG gneisses from the Zanhuang Complex. The protolith of the gneisses, predominantly tonalite, has undergone intensive metamorphism, deformation and anatexis and in a banded structure is intimately associated with melanocratic dioritic gneiss and leucocratic trondhjemitic veins. SHRIMP Zircon U–Pb data show that the tonalite was formed ca. 2692±12Ma ago. The tonalitic gneiss has the features of high SiO2 (67.76–73.31%), high Al2O3 (14.38–15.83%), rich in Na2O (4.48–5.07%) and poor in K2O (0.77–1.93%). The gneiss is strongly fractioned in REE ((La/Yb)N =12.02–24.65) and shows a weak positive Eu anomaly (Eu/Eu* =1.05–1.64). It has high contents of Ba (199–588ppm) and Sr (200–408ppm), low contents of Yb (0.32–1.00ppm) and Y (3.41–10.3ppm) with high Sr/Y ratios (21.77–96.77) and depletion in HFSE Nb, Ta and Ti. These characteristics are similar to those of the high-Si adakitic rocks. The melanocratic dioritic gneiss has low SiO2 (59.81%), high MgO (6.34%), high Al2O3 (14.02%) contents, rich in Na2O (3.7%) and poor in K2O (1.79%), with high Mg index (Mg# =67). REE and trace elements are on the whole similar to that of the tonalitic gneiss, but compatible element abundances V (116ppm), Cr (249ppm), Co (37ppm) and Ni (179ppm) are higher. The leucocratic felsic bands (approximating trondhjemite in composition) have major oxides similar to that of the TTG gneisses but the REE and compatible elements are extremely low, which are indicative of the products of anatexis. The tonalitic gneiss has positive ε Nd(t) (2.37–3.29) and low initial Sr (0.69719–0.70068) values with depleted mantle Nd model age of ca. 2.8Ga, suggesting its generation from partial melting of mantle-derived juvenile crust. The dioritic gneiss was also derived from subduction environment, but has undergone significant metasomatism of mantle wedge. The delineation of the ca. 2.7Ga TTG gneisses in the Zanhuang Complex further proves that the North China Craton experienced large-scale continental crustal accretion in early Neoarchean, and gives new constraints on the subdivision of the early blocks and greenstone belts of the craton. [Copyright &y& Elsevier]

Abstract: Western Shandong Province (WSP) is one of the typical Neoarchean granite-greenstone belts in the North China Craton (NCC). The Taishan association, consisting of a ∼2.7Ga komatiite–tholeiite sequence and a ∼2.5Ga felsic volcanic-sedimentary sequence, is the major supracrustal assemblage in the WSP. The ∼2.7Ga komatiite–tholeiite sequence can be subdivided into the Yanlingguan and Liuhang units. The 150–800m thick basaltic lava sequence of the Liuhang unit is exposed in the Qixingtai area, with the bottom unit composed of massive and layered basalts. Pillow basalts and tuff dominate the upper parts of the sequence. We report a weighted mean SHRIMP 207Pb/206Pb zircon age of 2706±9Ma (MSWD=0.61) for a trondhjemitic dike that intrudes the base of the pillow basalts, constraining the timing of this sequence to be older than this age. The basaltic lava sequence in the Liuhang unit is characterized by voluminous tholeiites and a minor component of enriched basalts. The tholeiites show relatively high MgO (5.5–9.0wt.%), but low TiO2 (0.8–1.3wt.%) and Nb (2.1–3.3ppm) contents. They display co-variations between Zr and other immobile trace elements and flat REE and trace elements patterns on chondrite- and primary mantle-normalized diagrams, respectively. In contrast, the enriched basalts have low MgO (3.6–5.4wt.%), but high TiO2 (1.6–2.2wt.%) and Nb (8.4–11.6ppm) contents. They display moderately enriched LREE and fractionated HREE patterns on chondrite-normalized diagrams. The basaltic sequence of the Liuhang unit displays a moderate range of initial ɛ Nd (−0.1 to +3.0) values. The element concentration and Nd isotopes of tholeiitic rocks in the Liuhang unit are comparable with the contemporaneous tholeiites in greenstone belts globally. In particular, the geochemical systematics of the tholeiite and enriched basalts show close similarity with those of the Wawa greenstone belt in the Superior Province. The Nb/Th, La/Smcn and Nb/La ratios of these basalts indicate that the basaltic lava sequence of the Liuhang unit has not been significantly affected by crustal contamination compared to the Yanlingguan komatiite–tholeiite sequence. The variation in lithology and geochemistry of basalts between the Liuhang and Yanlingguan units reflects a lateral change in composition of the ∼2.7Ga basaltic eruption. We propose that the komatiite–tholeiite sequence in the Taishan association was derived from an upwelling mantle plume with eruption close to the continental margin within an ocean basin. Our study does not provide any evidence to support that the WSP granite-greenstone belt was subjected to significant arc–plume interaction during the early Neoarchean. Our results contribute to the understanding of early Neoarchean crustal growth globally identified from different regions. [Copyright &y& Elsevier]

Abstract: In the Daqingshan area within the Khondalite Belt of the North China Craton, Paleoproterozoic gabbro and dolerite intrusions show amphibolite to granulite-facies metamorphism. U–Pb zircon dating and whole-rock geochemistry were undertaken on these rocks in order to understand the timing of mantle magmatism and thermal processes. Ten samples yielded zircon U–Pb formation ages of 2.46–2.44Ga, 1.97–1.92Ga and 1.84Ga and metamorphic ages of 1.95–1.83Ga. They are variable in geochemical composition with some being enriched in light rare earth and large ion lithosphere elements but depleted in Nb–Ta. Combined with previous results, it is concluded that mafic magmatism at 2.45–2.37Ga and 1.97–1.92Ga indicates two Paleoproterozoic extensional phases, with the latter accompanied by HT–UHT metamorphism as a result of underplating of mantle magma. [Copyright &y& Elsevier]