• 责任者：Song Xiangfeng (Chengdu University of Technology ; Chengdu 610059 ; China) ; Liu Xianfan
• 刊名：Acta Petrologica et Mineralogica
• 出版年：2007
• 卷期：26(4)
• 关键词：交代作用 ; metasomatism ; 碱性正长岩 ; alkali syenites ; 云南 ; Yunnan Province
• 页码：p.310-314
• 图表：1 illus., 2 tables, 25 refs.
• 分类号：0801
• issnNo：ISSN1000-6524
• isbnNo：CN11-1966/P

There are many deep xenoliths in silicified aegirine syenite porphyry of Xiaoqiaotou area, western Yunnan Province. A petrographic analysis combined with electron microprobe analysis and SEM shows that black opaque matters, whose composition is mostly of microcrystalline silicate and magnetite, are widely found running reticulate through mineral particles, crystals and cleavage cracks in association with metasomatic alteration in the mafic-ultramafic xenoliths and their host rocks. It is concluded that microcrystalline silicate and magnetite show characteristics of liquation in the back-scattered electron image. Such a microcrystalline solid, which assumes black opaque state under transmitted-light microscope and might have resulted in metasomatic alteration, is one of the direct microcosmic manifestations of mantle fluid metasomatism with characteristics of melted and supercritical fluids.