Zones of crust-mantle and lithosphere-asthenosphere interaction in eastern China: Characteristics and timing of transformation

Abstract: There exist Meso-Cenozoic crust-mantle and lithosphere-asthenosphere interaction zones in the lower lithosphere beneath eastern China, which are also two important magma sources. The heat and material exchanges between crust and mantle and between lithosphere and asthenosphere in the interactions and their dynamic processes are the critical mechanisms for thickness readjustment in the interior of the Meso-Cenozoic lithosphere, lithospheric uneven thinning and tectono-magmatic mineralization. Three types of crust-mantle interaction can be recognized in the interior of the continent; they are the interactions between mantle-derived underplating melts and the lower crust, between the delaminated lower crust and weakening lithospheric mantle and between the deeply subducted crust and mantle wedge in the continental-continental collision zone. Although the volcanic rock associations formed by the three types of crust-mantle interaction are somewhat different, their magma sources all contain crustal components. The lithosphere-asthenosphere interaction zone is also a major component of the magma source, which consists predominantly of asthenospheric mantle and in the main contains no crustal component. Lithospheric thinning was largely coeval with large-scale asthenosphere-derived basalt eruption and also with transformation of the two types of interaction. It occurred about 100 Ma later.