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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]

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]

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]