Intense alkaline magmatism and related Nb-REE mineralization occurred during the Silurian in the South Qinling belt, forming igneous rocks including syenites, carbonatites, trachytes and alkali basalts. The alkaline magma erupted during 450~430 Ma, at the same time with intense ultramafic and mafic activities in the region. These alkaline rocks were formed through fractional crystallization from mantle-derived magmas. The magma sources were likely composed of dominated HIMU mantle and minor EMI and EMⅡ mantle. The high values of alkali (K₂O+Na₂O) and protracted fractional crystallization constituted important geodynamic controls on the Nb-REE mineralization. The Silurian alkaline magmatic activities were generated in an intensive lithospheric extension and mantle upwelling setting, while the enriched lithospheric mantle was metasomitized by slab melts related to the subduction system.