华北克拉通中条山西南段新太古代末富钠和富钾花岗岩的成因及其地质意义OA

The Late Neoarchean witnessed a significant compositional transition of the continental crust in the North China Craton from sodium-rich to potassium-rich,marking a key stage of crustal maturation.However,the precise timing and processes of this transition remain unclear.In this study,we present an integrated analysis of petrogra-phy,geochemistry,zircon U-Pb geochronology,and Lu-Hf isotope for Late Neoarchean sodium-rich and potassium-rich granites from the southwestern Zhongtiao Mountains.The purpose of this study is to constrain their formation ages and source characteristics,and to explore their dynamic background and implications for continental crust mat-uration.Zircon U-Pb dating indicates that both the trondhjemitic gneiss and the monzogranite were formed in the late Neoarchean,with crystallization ages of 2 531±18 Ma and 2 527±54 Ma,respectively.Whole-rock major and trace element data,together with zircon Lu-Hf isotopes,suggest that the trondhjemitic gneiss was mainly formed by the partial melting of the mafic rocks in the lower crust in the early Neoarchean,while the monzogranites were pri-marily derived from partial melting of ancient high-to medium-K basaltic lower crust,with a minor contribution from metasedimentary rocks(mainly graywacke).Combined with regional geological evidence,we propose that the diverse Late Neoarchean granitoids in the Zhongtiao Mountains were generated by partial melting of sources at differ-ent crustal depths,including mafic lower crust,and minor metasedimentary rocks,likely triggered by mantle plume activity.The emplacement of the potassium-rich granite at～2.53 Ga signals crustal maturation in this region,reflecting the stabilization of the local continental crust.