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This study reports new LA‐ICP‐MS U–Pb zircon ages from the Xinghuadukou Complex from the Erguna Block, NE China. A suite of the Palaeoproterozoic orthogneiss and a suite of the Vendian to Cambrian paragneiss are recognized with the co‐magmatic age of 2,464 ± 26 Ma and the maximum depositional age of 561 ± 10 Ma for their igneous and sedimentary protolith, respectively. The trace element geochemical analysis suggests a strong arc affinity for our orthogneiss, characterized by the enriched LREE and LILE, the elevated incompatible and fluid‐mobile elements and the depleted yet negligible fractionated HREE and HFSE. By comparing our samples with a suite of Cenozoic mantle‐derived granitoids from Hokkaido and a suite of Mesozoic active continental margin volcanics from NE China, it is suggested that the igneous protolith of our near Archaean orthogneiss formed in an arc environment and probably derived from the prior arc crust. The trace element features of the paragneiss highly resemble that of the orthogneiss, showing arc affinity, which suggests an arc basin environment for the sedimentary protolith of our Vendian to Cambrian paragneiss. Based on the synthesized evidence from the Xinghuadukou Complex, a new tectonic scenario is proposed that the basement of the Erguna Block might be forged by the accretion and collision of multi‐episodic igneous arcs and their correlated arc basins, which was probably lasting through the Proterozoic and followed by the Pan‐African period high‐grade metamorphism. The consolidated Erguna Block was later involved into the CAOB tectonic domain, modified and disrupted with the assembly of NE China. [ABSTRACT FROM AUTHOR]

• The geochemical data were first presented for t a suite of Precambrian amphibolites in the Xinghuadukou Complex. • It is suggested that these metabasalts were generated in an oceanic crust developed from the back-arc extension due to the intra-oceanic subduction. • A new model is proposed for the evolution of NE segment of the Paleo-Asian Ocean. One of the geological attractions of the Xinghuadukou Complex resides in a suite of well exposed amphibolites outcropped locally in the northern part of the Xinlin-Xiguitu Suture zone between the Erguna and the Xing'an blocks in NE China. This suite of amphibolites occurs with gneisses, leptynite, schists, migmatitie and marbles from the Xinghuadukou Complex. Previously, only geochronological studies have been carried out on these amphibolites, suggesting a Late Neoproterozoic to Early Cambrian protolithic age (i.e. 547 ± 46 Ma). However, with only geochronological studies, it is insufficient to solve the controversy surrounding the tectonic settings of these amphibolites, such that the Precambrian evolution of the Xinlin-Xiguitu Suture cannot be further constrained. In this study, our new lithological and geochemical data indicate that these amphibolites are tholeiitic basalts with E-MORB affinities, which were most likely derived from the partial melting of a lithologically-mixed source of fusible eclogite and peridotites within the asthenosphere mantle under lithosphere thinning. Together with the previously reported Mid-Neoproterozoic suprasubudction-related ophiolites (i.e. 620–690 Ma) and ca. 516 Ma Toudaoqiao blueschists from this region, these amphibolites are suggested to be generated on the oceanic crust formed from the back-arc extension due to the intra-oceanic subduction. This interpretation provides new constraints not only on the tectonic implication of the Xinghuadukou Complex, but also the tectonic evolution of the Xinlin-Xiguitu Ocean within the Paleo-Asian Ocean regime. [ABSTRACT FROM AUTHOR]

The Beishan Orogenic Belt (BSOB) in China plays a pivotal role in understanding the tectonic evolution of the southern Central Asian Orogenic Belt. Despite numerous studies primarily emphasizing on Phanerozoic events, the existence and significance of Precambrian rocks in the BSOB still remain controversial. Here we report new geochemical and zircon U–Pb–Hf isotopic data for the Gubaoquan ortho- and paragneisses in the BSOB and the comparable Xingxingxia orthogneisses in the Central Tianshan Orogenic Belt to constrain their age, petrogenesis and tectonic implications. New LA-ICPMS U–Pb zircon dating results of zircon reveal that the protoliths of the Gubaoquan orthogneisses crystallized at 905–871 Ma, while the Gubaoquan paragneisses yielded an age peak at 1040–910 Ma with a maximum depositional age of ∼871 Ma. They are the oldest rocks discovered in the BSOB, mainly distributed in the southern units and interpreted as primary sources for the local Phanerozoic igneous and sedimentary rocks. The intrusion age of the Xingxingxia orthogneisses was ∼1014 Ma. All the Gubaoquan and Xingxingxia orthogneisses show low A/CNK, Rb/Sr and Rb/Ba ratios and similar depletion of Nb, Ta and Ti, akin to I-type granitoids related to subduction. However, the former have much lower Sr contents and Sr/Y ratios, lower light to heavy rare earth element fractionation (LREE/HREE = 4.43–10.12), and weaker negative Eu anomalies, related to a back-arc setting at low pressures, whereas the latter formed at high pressures in a continental arc setting. Zircon Hf-isotope compositions in the Gubaoquan ortho- and paragneisses exhibit a large range of ɛ Hf ( t ) values from −3.77 to +5.29, and two-stage model ages ( T C DM ) of 1.98–1.44 Ga, while those in the Xingxingxia orthogneisses are clustered with slightly higher ɛ Hf ( t ) values (+4.02 to +8.53) and younger T C DM ages (1.60–1. 34 Ga). The protoliths of both the Gubaoquan and Xingxingxia orthogneisses were derived from the mixing of basaltic magmas and those derived from the partial melting of meta-greywackes. Based on a review of Neoproterozoic events, the BSOB tends to closely link with the Chinese Tianshan Orogenic Belt and Tarim Craton. They were most likely located in the periphery of the already assembled Rodinia supercontinent. [ABSTRACT FROM AUTHOR]