Petrogenesis of coeval charnockites, mafic microgranular enclaves, and leucogranite dykes in a post-collisional setting: Late Palaeoproterozoic Luyashan pluton, western Trans-North China Orogen

The Luyashan charnockite-mafic microgranular enclaves (MMEs)-leucogranite association provides new insights into post-collisional magmatism in the Late Palaeoproterozoic Western Trans-North China Orogen, North China Craton. Here, we investigate the genetic relationships among MMEs (1815 ± 8 Ma and 1800 ± 9 Ma), their host charnockites (1806 ± 5 Ma), and coeval leucogranite dykes (1811 ± 8 Ma). The MMEs are marked by ovoid quartz ocelli, resorbed feldspar xenocrysts, elevated abundances of compatible elements, disparate ε _Hf (t) (−4.2 to +1.3), and partly retain an enriched-mantle affinity. The host charnockites contain primary orthopyroxene and are intermediate, ferroan (FeO _t /(FeO _t +MgO) = 0.78–0.87), calc-alkaline, high-K, and metaluminous. Their negative zircon ε _Hf (t) values (−7.0 to −3.2) and two-stage Hf model ages of 2551–2859 Ma indicate derivation from ancient lower crust that subsequently hybridized with mantle-derived components. The leucogranites exhibit ε _Hf (t) values (−7.4 to −4.7) overlapping those of regional ancient crust and preserve relict interstitial orthopyroxene, consistent with the magma derived from ancient crust that intruded into the incompletely consolidated charnockitic mush. Collectively, these results link enriched lithospheric-mantle recharge and ancient-crustal reworking to post-collisional thermal relaxation and extension of the Trans-North China Orogen at ca. 1.8 Ga.