武夷山中段加里东期混合岩的特征及成因讨论

武夷山中段出露的加里东期混合岩中广泛发育交代结构，可划分出钠－钙交代、钾交代和磋交代等三个阶段．岩石中微斜长石为最大微斜长石．浅色体与基体内外长石的Ａｎ值明显不同，且无环带构造．黑云母成分与围岩中的黑云母接近．岩石化学成分的变化与交代作用的类型有关．微量元素具有与围岩相似的特征，仅重稀土含量高于围岩．质量平衡计算表明，它们形成于开放体系中，矿物颗粒呈聚集分布．这些特征表明它们是由原来的变质岩经减质流体交代形成的。

STUDIES ON GENESIS AND CHARACTERS OF CALEDONIAN MIGMATITES IN MIDDLE WUYI MOUNTAINS

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.