摘要
The Xihuashan granitic complex is characterized by enrichment in rare-earth elements (REE). In particular, the second-stage granite (G-b) is markedly enriched in yttrium, and therefore contains complex associations of Y-bearing minerals. In this granite, garnet displays specific yttrium zoning with an Y-rich core and a 揷lean?rim. Besides minute inclusions of Y-bearing minerals, garnet involves a striking amount of Y and HREE in its central area. It is suggested that enrichment in Y in the garnet core accords with that in the melt as a result of REE magmatic fractionation. However, the 揷lean?rim may be the direct result of accumulation of fluid phases in the magma, which is virtually unfavorable for the entrance of REE in the garnet structure.
The Xihuashan granitic complex is characterized by enrichment in rare-earth elements (REE). In particular, the second-stage granite (G-b) is markedly enriched in yttrium, and therefore contains complex associations of Y-bearing minerals. In this granite, garnet displays specific yttrium zoning with an Y-rich core and a 揷lean?rim. Besides minute inclusions of Y-bearing minerals, garnet involves a striking amount of Y and HREE in its central area. It is suggested that enrichment in Y in the garnet core accords with that in the melt as a result of REE magmatic fractionation. However, the 揷lean?rim may be the direct result of accumulation of fluid phases in the magma, which is virtually unfavorable for the entrance of REE in the garnet structure.
基金
supported by the National Natural Science Foundation of China(Grant Nos.40025209 and 40221310)
the Ministry of Education of China (Grant No.2000028431)
关键词
钇
石榴石
花岗岩
岩石学
岩浆
水热作用
garnet, zoning, yttrium, magmatic-hydrothermal process, the Xihuashan granitic complex.
