摘要
The present paper gives a review on the researches of trace element compositions in magmatic,metamorphic and hydrothermal zircons.Trace element characteristics of zircon reflect a number of information about its host rocks including the compositional evolution of host rocks,the coexisting fractionation phases,magma mixing process and the character of the melting source region.The trace element composition of igneous zircon varies systematically with the trend of increasing trace element abundance in zircons from ultramafic through mafic to granitic rocks.Mantle-affinity zircons have lower trace element abundance,and the REE patterns show slight or without significant Eu-anomaly and relatively flat HREE patterns.Crust-affinity zircons have higher trace element abundance,and the REE pattern shows a steeply-rising slope from the LREE to the HREE with an intensively positive Ce-anomaly and negative Eu-anomaly.Variations of trace element composition within single zircon grains and between populations may reflect variations of magma composition.Crystallization of newly-grown zircon or modification of inherited zircons occurred under a wide range of temperature and pressure during prograde,retrograde and peak metamorphism.Growth mechanisms include solid state recrystallization,dissolution recrystallization,and nucleation-crystallization related with Zr released from metamorphic reactions.Metamorphic zircons have complicated internal textures,and their trace element characteristics show correlation to growth mechanisms,coexisting minerals and forming environment.Hydrothermal zircon may exhibit oscillatory zoning that is also typical for igneous zircon.Fluid and hydrothermal mineral inclusions can clearly define its hydrothermal origin.Trace element composition of hydrothermal zircon reflects the features of hydrothermal mineral assemblage and the composition of fluids.