The influence of diffentiation of magmas of rare metal lithium-fluorine granitoids on primary strontium isotopic composition (on the example of Yugodzyr Massif, Mongolia)

Isotopic Sr composition in two differentials of Yugodzyr Massif of rare metal lithium-fluorine granitoids of the South-Eastern Mongolia was investigated to study the influence of differentiation of magmas of rare metal lithium-fluorine granitoids on the value of primary 87Sr/86Sr(Isr0) ratio in granitoids. It is shown that amazonite-albinte granites are characterized by higher ISr0 value, than initial leucogranites at fractional differentiation of leucogranite magma. The period of magma exposition is evaluated according to the difference between ISr0 in initial granites and deeply differentiated one. This period for Li-F granite magma of the Yugodzyr Massif is equal to ∼ 350000 years. 4 refs.; 2 figs