东天山花岗岩体矿物稀土元素地球化学及极限分配系数

REE GEOCHEMISTRY AND ESTIMATED LIMIT PARTITIONING COEFFICIENTS OF MINERALS FROM GRANITE MASS, EASTERN TIANSHAN MOUNTAINS, CHINA

新疆东天山１５个花岗岩体中５５个单矿物的稀土元素分析表明：造岩矿物加权稀土元素质量分数仅占全岩稀土元素的２５％；尽管在花岗岩成分体系中大部分稀土元素表现出相容性，但Ｅｕ是不相容的；矿化花岗岩和碱长花岗岩中的长石以低ｗ（ＬＲＥＥ）／ｗ（ＨＲＥＥ）和较小的Ｅｕ正异常（碱性长石的δ（Ｅｕ）＜６，斜长石的δ（Ｅｕ）＜４）为特征；不同类型的花岗岩中的副矿物对全岩的稀土元素的贡献不同．根据结晶顺序，计算出了一些稀土元素在造岩矿物和长英质熔体间的极限分配系数．这些分配系数的应用。

REE analyses have been made of 55 individual minerals in 15 representative granite masses in the eastern Tianshan mountains, Xinjiang Uygur Autonomous Region, China. The results show that weighted REE contents of the rock_forming minerals are determined to be 25%. The majority of REE in the granite component system are compatible, except the europium. The feldspars in mineralized and alkali_feldspar granites are characterized by the lower w (LREE)/ w (HREE) ratios and by the smaller europium positive anomalies ( δ (Eu)<6 for alkali_feldspars, and δ (Eu)<4 for plagioclases). Accessory minerals of different kinds play different roles in their contribution to the REE in the corresponding host rocks. The limit partitioning coefficients of some REE between rock_forming minerals and felsic melts are therefore calculated in line with the order of their crystallization. The application of these partitioning coefficients will effectively avoid impractical high contents of the accessory minerals rich in REE in the initial and (or) relict phases that might occur during the simulation of granitoid origin.