Early Neoarchean alternation of plate subduction and deep mantle upwelling

How Earth switched from any earlier regimes such as plume-lid tectonics to plate tectonics remains an unresolved issue in Earth sciences. We report early Neoarchean (-2.77-2.68 Ga) metavolcanic rocks, including older calc-alkaline basaltic-andesitic rocks in the southwest but younger tholeiitic rocks in the northeast, from the Jiaobei terrane of North China Craton. Petrogenetic studies and thermodynamic and trace element modeling reveal that the tholeiitic magmas originated mainly from deep and unmodified mantle sources (-1600 degrees C and -3.5 GPa), relative to the shallower and metasomatized depleted mantle sources (-1450 degrees C and -2.2 GPa) of calc-alkaline magmas. Geochemical changes indicate that the mantle sources became isotopically enriched but less metasomatized from southwest to northeast. These data suggest an early Neoarchean plate subductioninduced deep mantle upwelling regime. We further depict a potential geodynamic framework for the early Neoarchean Earth involving active interaction of plate subduction and deep mantle upwelling, which possibly changed the thermal evolutionary trajectory of the Earth and accelerated the arrival of global plate tectonics.