Petrogenesis delineation of the felsic intrusive rocks in the eastern North China Craton: Implications for crustal evolution and geodynamic regimes

As the dominant component of the continental crust, Archean intrusive granitoids can provide significant insights into the growth and evolution of the early crust. In this study, we report a systematic geochronological and geochemical study on a tonalite-trondhjemite-granodiorite (TTG1)-granites (G2)-quartz monzonite (QM) assemblage in the northeastern North China Craton (NCC). Zircon U-Pb dating shows that they were emplaced during 2506-2549 Ma. Their geochemical features, such as REE concentrations, patterns and ratios, superchondritic Nb/Ta ratios, and similarity to the HP-MP TTGs, suggest residues of garnet-amphibolite-to eclogitefacies. TTGs in Group I show high Sr and low Y concentrations and negligible/pronounced negative Eu anomalies, reflecting rare or a small quantity of plagioclase residue. Positive Eu anomalies of Group II possibly indicate involvement of varying amount of accumulative plagioclase, and that garnet fractionation also plays a role. High MgO, Mg#, Cr and Ni, and positive epsilon Hf(t) varying from juvenile to evolved signatures, suggest that the TTGs were generated under a continental arc setting. The granitic rocks (G2-QM) were generated by melting of predominant TTGs and subordinate metasedimentary rocks, with late-early Neoarchean TTGs, Mesoarchean TTGs, and Eoarchean crustal material in the NCC involved. Isotopic evidence shows that 2.7-2.9 Ga crustal reworking predominates the formation process of the granitoids. The study area witnessed a long period of crust extraction from Eoarchean to the end of Neoarchean. Subduction-related magmatisms at late Neoarchean are widespread in the world.

Automated summary

This study on a tonalite-trondhjemite-granodiorite (TTG)-granites-quartz monzonite assemblage in the northeastern North China Craton provides insights into the growth and evolution of the early continental crust. Geochemical and geochronological analysis reveals the residues of garnet-amphibolite-to-eclogite facies in the TTGs, indicating a continental arc setting for their formation. The involvement of various crustal materials from different geological eras suggests a complex crustal evolution process.