摘要
独居石和氟碳铈矿是超大型稀土矿床——白云鄂博矿床中最主要的稀土矿物。对独居石的氧同位素研究工作国内外开展得很少，本研究对独居石氧同位素制样方法进行了讨论。在计算的独居石－水氧同位素分馏方程：１０３ｌｎα＝－０．０９１－４．２２４×（１０３／Ｔ）＋３．８９６×（１０６／Ｔ２）基础上，分析了矿床白云石型矿石和萤石型矿石中独居石的氧同位素组成。独居石δ１８Ｏ值的变化范围为３．５‰—１１．４‰，其中，在萤石型矿石中明显偏低，为３．５‰—４．５‰，白云石型矿石δ１８Ｏ变化范围较大。计算的形成温度主要在３２５—５６３℃之间，与包裹体测温数据相一致。成矿热液δ１８Ｏ值分为两组，一组近于岩浆水，另一组则很低，这说明了矿床独居石形成条件变化较大。
Monazite is the most widespread REE mineral in Bayan Obo ore deposit,a superlarge REE-Fe-Nb deposit.As oxygen isotopic study has rarely been done beforefor monazite,the analytical procedure for oxygen isotopic determination of monazite was discussed.Based upon the calculated O-isotopic fractionation expression between mziteand water:10 3lmα=-0.091-4.224×10 3/T)+3.896×10 6/T 2)O isotopic compositions of monazites in dolomite ore and fluorite ore were discussed.The δ 18 O value of monazite varies from 3.5‰ to 11.4‰ ,with a lower values between 3.5‰ and 4.5‰ for those in fluorite ore and a large variation in dolomite ore.The calculated equilibrium temperature is mainly between 325—563℃,which is in accordance with the data from fluid in clusions.According to δ 18 O vlues,the ore-forming fluid can be divided into two groups:one is similar to those of igneous sureces,another is very low in δ 18 O ,implying a very wide range of ore formation condition.THis may be the result of superpositon of various genetic processes.
出处
《地球化学》
CAS
CSCD
北大核心
1997年第1期45-53,共9页
Geochimica
基金
国家自然科学基金
中国科学院矿床地球化学开放研究实验室基金
