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Magmatic and metasomatic rock suites can be commonly found in active convergent margins as the suprasubduction zone mantle wedge is usually impregnated by melts and fluids. Here we present petrologic, whole-rock geochemical and zircon U-Pb and Lu-Hf data from metamorphic intermediate-mafic and ultramafic rocks in central Jilin Province, NE China, to constrain the Early Paleozoic tectonic evolution of the southeastern margin of the Xing'an-Mongolia Orogenic Belt. Lithologically, the meta-igneous rocks are composed of plagioclase-actinolite, meta-allgovite, tremolitized pyroxenite, and serpentinized peridotite. Geochronological results indicate that the protoliths of the meta-igneous rocks formed during the Early–Middle Ordovician (474–466 Ma). Geochemical features suggest that the rocks are calc-alkaline and transitional-series rocks relatively enriched in large-ion lithophile and light rare earth elements and depleted in high field strength and heavy rare earth elements, implying that they formed in a supra-subduction zone environment. Additionally, the protoliths of the plagioclase-actinolites, which display an affinity for sanukites, resulted from an equilibrium reaction between mantle peridotite and slab melts derived from the partial melting of subducting sediments during early-stage subduction; the meta-allgovite rocks were likely derived from a juvenile depleted lithospheric mantle that was metasomatized by subduction-related fluids; the ultramafic rocks are magmatic cumulates formed in a suprasubduction zone mantle wedge. Furthermore, the meta-allgovite rocks display both arc-like and MORB-like geochemical characteristics, suggesting an intra-continental back-arc basin setting. These features, combined with the presence of the abundance of zircon xenocrysts with Neoproterozoic–Paleozoic ages, as well as the results of previous studies, reflect that a small-scale and limited back-arc basin, which was related to the northward subduction of the Paleo-Asian oceanic plate, probably existed close to the Songnen-Zhangguangcai Range Massif during the Early–Middle Ordovician. [ABSTRACT FROM AUTHOR]

To constrain the tectonic evolution of the eastern segment of the Paleo-Asian Ocean, we conducted zircon U–Pb-Hf dating and whole-rock geochemical analyses for metasedimentary rocks from the Dongnancha Formation in the Huadian area in central Jilin Province, Northeastern (NE) China. Most detrital zircons from the metasedimentary rocks display clear oscillatory zoning and striped absorption in cathodoluminescence (CL) images and have Th/U ratios of 0.1–1.8, thus indicating a magmatic origin. U–Pb isotopic dating using LA-ICP-MS method for zircon samples from the metasedimentary rocks reveals that the depositional age can be constrained to the period between 250 and 222 Ma. Geochemical data reveal low to intermediate degrees of weathering of the source material and compositionally low to intermediate maturity. Detailed analyses of detrital zircon U–Pb-Hf geochronology and geochemistry show that these metasedimentary rocks are derived from a bidirectional provenance. The predominant derivation is from Permian–Early Triassic felsic-intermediate igneous rocks of central Jilin Province and adjacent regions in the northern margin of the North China Craton, although felsic-intermediate igneous rocks and continental material in the eastern segment of the Central Asian Orogenic Belt from the Cambrian–Carboniferous represent additional sources and minor amounts of Paleoproterozoic–Neoproterozoic material have been input from the North China Craton. A number of geochemical indicators and tectonic discrimination diagrams collectively indicate a continental island arc-active continental margin setting for the deposition of the protoliths of the metasedimentary rocks. The results of geochemical and geochronological analyses of the provenance and tectonic setting of the metasedimentary rocks indicate that the Dongnancha Formation was likely deposited in an intermountain basin in a post-orogenic fast uplift setting, suggesting that the final closure of the eastern segment of the Paleo-Asian Ocean in the Huadian area of central Jinlin Province likely occurred between the Early Triassic and Middle Triassic. [ABSTRACT FROM AUTHOR]