REE distribution in the Li-bearing metasomatized metapelites of the Etyka ore field, Eastern Transbaikalia

The unique Li-bearing metasomatic deposit formed in the outer contact of th e Etyka Ta-bearing amazonite granite massif was studied. The metasomatites were formed in the pregranite and syngranite stages. The pregranite stage w as characterized by temperature variations and related fluctuations in the fluid and alkalinity regimes. Unlike the syngranite greisenization, the pre granite high-temperature greisenization was associated with REE introductio n progressively enhancing with an increase in fluid (F, P) activity. The RE E precipitation in different zones of the metasomatic columns was not unifo rm and was controlled by REE affinity to volatiles, as well as by the alkal inity regime and presence of favorable geochemical barriers and REE-concent rating minerals such as fluorides (fluorite, weberite, sellaite) and phosph ates (Sr-bearing apatite, goyazite-gorceixite, and monazite).