STUDIES ON GENESIS AND CHARACTERS OF CALEDONIAN MIGMATITES IN MIDDLE WUYI MOUNTAINS
武夷山中段加里东期混合岩的特征及成因讨论

In the Caledonian migmatites in middle Wuyi Mountains,there are widely developed metasomatic textures which are divided into Na-Ca-metasomatic,K-metasomatic and Simetasomatic stages.Microclines are formed in the condition of low temperature.Plagioclases in mesosomes and leucosomes have no zoned textures and have different An content.The chemical composition of biotites in leucosomes and malenosomes approaches that of biotites in well-rocks.The differences of petrochemical compositions in various migmatites is large and is related to metasomatic types.Trace element distribution of migmatites is similar to that of metamorphic well-rocks,except for their HREE content is higher than that of wellrocks.Migmatites are formed in open-system according to mass-balance calculation.Mineral grain contact relations of migmatite show.an aggreggate distribution.So we suggest that the migmatites are formed by metasomatism of alkaline fluid for metamorphic resource rocks.