阿尔泰三号伟晶岩脉岩浆演化过程中铌、钽示踪的研究

THE TRACKING STUDY OF Nb AND Ta IN MAGMATICEVOLUTIONARY PROCESS FOR PEGMATITEVEIN No.3, ALTAY, CHINA

对三号伟晶岩脉某些不相容元素的分异与演化进行了研究，结果表明，岩浆作用中的不相容元素Nb、Ta的不相容性在花岗伟晶岩浆演化过程中已大大减弱，Nb、Ta独立矿物如铌钽铁矿、细晶石等能形成于伟晶质熔体的各个演化阶段。依据地质观察和分析数据对三号伟晶岩脉的分离结晶过程进行恢复。同时，计算了Nb、Ta在熔体与白云母、微斜长石、钠长石、锂辉石等主要矿物之间的分配系数，对Nb、Ta的成矿作用也进行了讨论。

The fractionation and evolution of some incompatible elements in pegmatite veinNo.3 are studied. The results show that the incompatibility of Nb and Ta is stronglylowered in the evolutionary process of granitic pegmatite magma. The Nb-Ta-independent minerals such as columbite, microlite etc. can form in each evolutionarystage of pegmatitic melts. The fractional crystallization process of pegmatite vein No.3can be reconstructed on the basis of geological observation and laboratory data.Meanwhile, the partition coefficients of Nb and Ta between melts andpegmatite-forming minerals such as muscovite, microcline, albite, spodumene etc. arecalculated in vein No.3 and mineralizations of both Nb and Ta are discussed too.