Neoarchean to Paleoproterozoic geodynamic transition of the North China Craton: Evidence from multi-phase metamorphism in the Southern Jilin Complex

Identifying multi-phase metamorphism from Archean cratons and establishing the pressure-temperature-time (P-T-t) paths will provide notable insights into the geodynamic evolution of the early Earth. In this contribution, an integrated analysis of petrography, mineral chemistry, phase equilibria modeling, geothermobarometer and geochronology is conducted for felsic and mafic granulites from the Southern Jilin Complex (SJC), North China Craton (NCC). The results show that the rocks record two phases of metamorphism. The first phase is represented by the granulite-facies assemblage of Grt + Opx + Pl + Qz in both kinds of rock. The felsic granulite exhibits a clockwise P-T path with peak conditions of 8.6-11 kbar and 800-850 ℃, while the mafic granulite shows an anticlockwise P-T path with peak conditions of 6.8-8 kbar and 735-770 ℃. The second phase is recorded by an overprinting assemblage of Grt + Hbl + Bt + Pl + Qz in the felsic granulite, exhibiting a clockwise P-T path with peak conditions of 7.5-10 kbar and 680-756 ℃. For the first-phase metamorphism, zircon U-Pb dating of felsic and mafic granulites yields ages of 2498 ±11 Ma and 2509 ±15 Ma, respectively, while hornblende ⁴⁰Ar/³⁹Ar dating of mafic granulite gives a cooling age of 2402 ±9 Ma. In-situ apatite U-Pb dating of felsic granulite yields a cooling age of 1742 ±13 Ma for the second-phase metamorphism. The coexistence of clockwise and anticlockwise P-T paths for the first-phase metamorphism may indicate a sagduction regime during the late Neoarchean. The second-phase metamorphism is inferred to be resulted from a late Paleoproterozoic collisional orogeny. Combined with previous data, this study documents a geodynamic transition in the NCC from pervasive vertical tectonism (potentially coexisting with horizontal tectonics) to dominant horizontal tectonism during the late Neoarchean to late Paleoproterozoic.