Zircon U-Pb chronological and geochemical characteristics of Paleoproterozoic meta-mafic rocks in Tonghua area, Southern Jilin Province: implication for the tectonic evolution of the Jiao-Liao-Ji Belt, North China Craton

As one of the most representative Paleoproterozoic orogenic belts in the North China Craton, the Jiao-Liao-Ji Belt is of great significance to explore the Paleoproterozoic tectonic evolution of the North China Craton, as well as the convergence process of the Columbia Supercontinent. In this study, we present new geochronological and geochemical data of Paleoproterozoic meta-mafic rocks in the Southern Jilin Province, NE China. Our primary objective is to further constraint the formation and evolution of the Jiao-Liao-Ji Belt. The zircon U-Pb dating reveals that the meta-mafic rocks crystallized at 2.2-2.0 Ga, followed by a metamorphism occurring at similar to 1.9 Ga. Additionally, most of the mafic rocks display moderate fractionation in both light rare earth elements (LREEs) and heavy rare earth elements (HREEs), suggesting their association with an arc setting. Furthermore, the rocks also display an enrichment in large ion lithophile elements (LILEs) such as Cs, Rb, Ba, and Pb, and depletion in high field strength elements (HSFEs) including Nb, Ta, Zr, and Ti. These geochemical characteristics suggest a back-arc setting, indicating that the meta-mafic rocks originated from asthenospheric mantle that was metasomatized by fluids or melts derived from the subducting slab. Notably, a shoshonitic metabasalt exhibits trace element and REEs patterns that resemble those of ocean-island basalts. This suggests that the shoshonitic metabasalt was formed in an oceanic island environment, likely generated from the asthenospheric mantle. Combining these findings with previous studies, we can conclude that the Jiao-Liao-Ji Belt is associated with arc-continental collision, indicating the presence of a modern-type plate tectonic regime in the northeastern North China Craton during the Paleoproterozoic period.