THE MAGMA EVOLUTION OF TIANCHI VOLCANO, CHANGBAISHAN

The Changbaishan Tianchi volcano is composed of the basaltic rocks at the shield-forming stage, the trachyte and pantellerite at the cone-fo rming stage and modem eruption. Studies on their REE, incompatible ele ments and Sr, Nd, Ph isotopes suggest that rocks at different stages h ave a common magma genesis and close evolution relationship with diffe rentiation crystallization playing the key role. The co-eruption of ba saltic trachyandesite magma and pantellerite magma indicates that ther e exist both crustal magma chamber and mantle magma reservoir beneath the Tianchi volcano.