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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]

This paper presents some data of the Jiaopingdu gabbro and Caiyuanzi granite at the southwestern margin of the Yangtze Block, on the geochemical compositions, zircon LA–ICP–MS U–Pb ages and Hf isotopic data. The Jiaopingdu gabbro gives the age of 1721 ± 5 Ma, the Caiyuanzi granite 1732 ± 6 Ma and 1735 ± 4 Ma, and the Wenjiacun porphyry granite 1713 ± 4 Ma, suggesting nearly contemporaneous formation time of the gabbro and granite. The bimodal feature is demonstrated by the gabbro SiO2 content of 44.64–46.87 wt% and granite 73.81–77.03 wt%. In addition, the granite has high content of SiO2 and Na2O + K2O, low content of Al2O3 and CaO, enriched in REEs (except Eu) and Zr, Nb, Ga and Y, depleted in Sr, implying it belongs to A‐type granite geochemistry and origin of within‐plate environment. The zircon ∊Hf(t) of the granite and gabbro is at the range of 2–6, which is near the 2.0 Ga evolution line of the crust, implying the parent magma of the gabbro being derived from the depleted mantle and a small amount of crustal material, and the parent magma of the granite from partial melting of the juvenile crust and some ancient crustal material at the same time. Compared with 1.8–1.7 Ga magmatism during breakup of other cratons in the world, we can deduce that the Columbia has initially broken since ca. 1.8 Ga, and some continental marginal or intra‐continental rifts occurred at ca. 1.73 Ga. [ABSTRACT FROM AUTHOR]

The Hutuo Group, located in the Wutai Mountains area, is characteristic of Paleoproterozoic strata in the North China Craton, and plays an important role in establishing evolutionary processes in the Trans-North China Orogen. We present petrological observations along with geochemical and Nd isotopic data for basalts in the Qingshicun and Hebiancun Formations of the Hutuo Group. These basalts are enriched in TFeO (11.97−18.01 wt.%), consistent with occurrences of iron-rich basalt world-wide. They also display relatively high MgO (4.95−12.25 wt.%), Ni (79−121 ppm) and Cr (37−101 ppm) and low in SiO 2 (41.37−51.95 wt.%). Therefore, the iron-rich character of the Hutuo Group basalts originated with their parental magma rather than via shallow crustal fractionation at low oxygen fugacity, as inferred for many high iron basalts. The Hutuo Group basalts exhibit weak to moderate differentiation of light REE over heavy REE ((La/Lu) cn = 2.61−6.79) with minor or slight Eu anomalies (Eu/Eu* = 0.77−1.41), and also show the Nb and Ti troughs without obvious Zr and Hf anomalies. The ɛ Nd ( t ) values of the basalts range from −1.23 to +0.81 with T DM of 2489−2664 Ma. The basalts most plausibly originated from the fertile subcontinental lithosphere mantle and, in the case of the Qingshicun Formation basalts, also underwent the crustal contamination. Basalts in the Hutuo Group also have the high Zr/Hf ratios, and present high Ti/V values of 24−55 and Zr/Y ratios ranging from 4.6 to 13.6, suggesting that they were emplaced in a within-plate setting. Considering the sedimentary associations and detrital fragments in the Hutuo and Gantaohe Groups, and bimodal magmatism along the Trans-North China Orogen, we propose that 2.2−2.0 Ga geological events within the orogen were rift-related, but did not result from subduction or island arc processes. [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]

Abstract: SHRIMP zircon U–Pb dating of the Huangjinshan granite porphyry in the Wutai area, North China Craton (NCC) yielded concordant ages, with a weighted mean 207Pb/206Pb age of 2137±9Ma, which indicates that the granite was emplaced in the middle Paleoproterozoic. The granite porphyry is enriched in SiO2, REEs (except Eu), Zr, Nb, Ga, Y and Zn, and depleted in MgO, CaO, Al2O3, Sr, Ba, V, Cr and Ni, with high FeO*/MgO ratios. With the zircon saturation temperatures ranging from 856 to 895°C and a lack on detected inherited zircon, this indicates it is a ‘hot’ A-type granite, of the type emplaced in anorogenic or extensional settings with high heat flow. Zircons in the granite porphyry have ε Hf(t) values ranging from −1.72 to +1.84, and Hf model T DM1 ages of 2429–2554Ma. The Hf isotopes indicate source of the granites was pre-Neoarchean continental crust mixed with mafic rocks derived from depleted mantle, or directly from the partial melting of ca. 2.5Ga crust. Given that there are no syn-plutonic gabbro enclaves in the Huangjinshan granite porphyry, it is preferred that it originated mainly from partial melting of ca. 2.5Ga upper crust without mixing with mantle-derived magma. 2.2–2.0Ga volcanic and plutonic rocks, which exhibit bimodal magma characteristics emplacing in rifting setting, are abundant in the central NCC. The results presented here are further evidence for that 2.2–2.0Ga is an important stage of Paleoproterozoic rifting in the central NCC. [Copyright &y& Elsevier]

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: 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: The Yunkai Terrane is one of the most important pre-Devonian areas of metamorphosed supracrustal and granitic basement rocks in the Cathaysia Block of South China. The supracrustal rocks are mainly schist, slate and phyllite, with local paragneiss, granulite, amphibolite and marble, with metamorphic grades ranging from greenschist to granulite facies. Largely on the basis of metamorphic grade, they were previously divided into the Palaeo- to Mesoproterozoic Gaozhou Complex, the early Neoproterozoic Yunkai ‘Group’ and early Palaeozoic sediments. Granitic rocks were considered to be Meso- and Neoproterozoic, or early Palaeozoic in age. In this study, four meta-sedimentary rock samples, two each from the Yunkai ‘Group’ and Gaozhou Complex, together with three granite samples, record metamorphic and magmatic zircon ages of 443–430Ma (Silurian), with many inherited and detrital zircons with the ages mainly ranging from 1.1 to 0.8Ga, although zircons with Archaean and Palaeoproterozoic ages have also been identified in several of the samples. A high-grade sillimanite–garnet–cordierite gneiss contains ∼242Ma metamorphic zircons, as well as ∼440Ma ones. Three of the meta-sedimentary rocks show large variations in major element compositions, but have similar REE patterns, and have t DM model ages of 2.17–1.91Ga and ε Nd (440Ma) values of −13.4 to −10.0. Granites range in composition from monzogranite to syenogranite and record t DM model ages of 2.13–1.42Ga and ε Nd (440Ma) values of −8.4 to −1.2. It is concluded that the Yunkai ‘Group’ and Gaozhou Complex formed coevally in the late Neoproterozoic to early Palaeozoic, probably at the same time as weakly to un-metamorphosed early Palaeozoic sediments in the area. Based on the detrital zircon population, the source area contained Meso- to Neoproterozoic rocks, with some Archaean material. Palaeozoic tectonothermal events and zircon growth in the Yunkai Terrane can be correlated with events of similar age and character known throughout the Cathaysia Block. The lack of evidence for Palaeo- and Mesoproterozoic rocks at Yunkai, as stated in earlier publications, means that revision of the basement geology of Cathaysia is necessary. [Copyright &y& Elsevier]

• The Paleoproterozoic granitiods in Fuping Complex were emplaced from 2063 Ma to 2082 Ma. • The Paleoproterozoic granitoids are A-type granites. • The Paleoproterozoic granitoids were derived from the melting of late Archean TTG gneisses. • The Paleoproterozoic granitoids formed in rift-related setting. Mid-Paleoproterozoic (2.2–2.0 Ga) magmatism in the Trans-North China Orogen (TNCO) is of great significance for the Paleoproterozoic geological evolution of the entire North China Craton (NCC). In this paper, we present geochemical, SHRIMP zircon U-Pb and Hf isotopic data on the 2.1–2.0 Ga granitoids in the Fuping Complex of the TNCO. These include the Nanying granitic gneiss, which yielded ages of 2075 ± 13 Ma, 2079 ± 9 Ma and 2073 ± 10 Ma, the Gangnan granitic gneiss, dated at 2081 ± 8 Ma, 2082 ± 14 Ma and 2063 ± 7 Ma, the Baiyangling granite with ages of 2077 ± 6 Ma, 2070 ± 19 Ma and 2069 ± 12 Ma, and the Shangzhuang granite, which yielded ages of 2072 ± 12 Ma and 2070 ± 12 Ma. The 2.1–2.0 Ga granitic rocks in Fuping Complex are enriched in SiO 2 , K 2 O + Na 2 O, rare earth elements (REEs) (except Eu), high field strength elements like Zr, Nb, Ga and Y, and depleted in CaO, Al 2 O 3 and Sr. Their Ga/Al ratios and absolute Zr + Nb + Y + Ce contents are high and their average Zr saturation temperatures are as high as 890 °C, all of which are consistent with the features of A-type granite. The ε Hf (t) values of zircon in all samples are much lower than that of the depleted mantle at the same stage, while Hf model T DM1 , T DM C ages have ranges of 2.3–2.7 Ga and 2.4–2.9 Ga, respectively, which are much older than the age of the granitoids. These zircon Hf model ages are similar to those of the Neoarchean TTG (Tonalite-Trondhjemite-Granodiorite) gneisses in the Fuping Complex. Therefore, based on a combination of petrology, geochemistry and isotopic characteristics, we infer that these four 2.1–2.0 Ga granitic plutons in the Fuping Complex are partial melts of the Neoarchean TTG gneiss generated in an extensional environment. Based on extensive data, the 2.1–2.0 Ga A-type granites and the mafic dikes in the Fuping Complex represent a bimodal magma association. Considering the sedimentary rocks of the Gantaohe Group, deposited in the same period, we deduce that the 2.1–2.0 Ga A-type granite in the TNCO Fuping Complex was emplaced in an intra-continental rift setting in the NCC. This evidence indicates that the North China Craton was initially stabilized at the end of the Neoarchean. [ABSTRACT FROM AUTHOR]