Mesozoic overprinting of the Precambrian Wuhe Complex, southeastern margin of the North China Craton: Insights from geochronology and geochemistry

The formation of Meso-Neoarchean metagranitoids from the Wuhe complex (WC), southeastern margin of the North China Craton (NCC) and the nature of Mesozoic tectonothermal overprinting are unclear. It is the importance of understanding Phanerozoic overprinting in Archean complexes for obtaining a complete under-standing of the evolution of the NCC. The WC is composed of-2.8 Ga granitic gneiss,-2.7 TTG gneiss, 2.1 Ga and 800-700 Ma granitic gneiss, all of which are intruded by 160 Ma granite. The Meso-Neoarchean rocks were affected by multiple tectono-magmatic-metamorphic thermal events at ca. 2.7 Ga, 1.85-1.80 Ga, 220 Ma and 160 Ma. Metamorphic overprinting at-220 Ma, anatexis at-160 Ma, and the presence of-750 Ma and-220 Ma inherited zircons in a 156 Ma granite strongly suggest that the Yangtze Craton (YC) were underthrust beneath the southeastern margin of the NCC by the late Triassic during continental subduction associated with the Dabie-Sulu orogeny. Lithological, geochemical, and isotopic evidence indicate that the-2.8 Ga granitic gneiss of the WC were derived from partial melting of previous continental crust; this provides a new petrogenetic interpretation of Mesoarchean (-2.8 Ga) granitic gneiss in the region. The-2.7 Ga TTG gneisses were derived from partial melting of juvenile basaltic crust with a contribution of ancient crustal material. The geochemical data, in conjunction with similar ages of inherited zircon (-2.7 Ga) and zircon from Neoarchean TTG gneiss (-2.7 Ga), indicate that the-2.1 Ga granitic gneisses were derived from partial melting of the Neoarchean (-2.7 Ga) TTG gneiss. In addition, newly-identified Neoproterozoic (800-700 Ma) granitic gneiss with Triassic metamorphic ages, combined with the Neoproterozoic and Triassic inherited zircons in the Jurassic granites, further suggest that the YC continental crust was subducted beneath the NCC in the Triassic and acted as the source region for the Jurassic granites at-156 Ma.