牦牛坪钙稀土氟碳酸盐多体矿物的成分特征及其成因意义  

Composition of Ca-REE Fluorocarbonate Minerals in Maoniuping and Implications to Their Genesis

作　　者：杨主明[1] Smith M Henderson P Le Bas MJ 陶克捷[1] 张培善[1] 

机构地区：[1]中国科学院地质与地球物理研究所,北京100029 [2]Department of Mineralogy.The Natural History Museum [3]Department of Geology.University of Southampton

出　　处：《中国稀土学报》2002年第1期61-67,共7页Journal of the Chinese Society of Rare Earths

基　　金：国家自然科学基金资助项目 ( 4 9872 0 2 0 );英国皇家学会资助

摘　　要：牦牛坪矿床中钙稀土氟碳酸盐多体矿物 ,经扫描电镜观察和电子探针分析 ,表明氟碳铈矿可由矿液直接结晶或通过多体矿物的分解反应形成。与多体矿物相比较 ,氟碳铈矿的稀土配分模式以富La为特点。多体矿物的CaO/REE2 O3 (重量比 )的平均值为 0 131(测试值 )和 0 14 1(计算值 ) ,低于氟碳钙铈矿的理论值 0 171。根据多体系列化学计量的线性关系 ,证明多体矿物形成于Ca2 +和CO2 - 3 活度较低的矿液中。The Ca REE fluorocarbonate minerals occurred in the Maoniuping REE deposit, Southwest China, were studied by scanning electron microscopy and electron microprobe. It indicates that Bastnaesite (Ce) formed either by the crystallization from the parent fluid or by the breakdown of polysomes of bastnaesite synchysite series. Bastnaesite (Ce) is relatively enriched in La, while the polysomes in Nd. For the polysomes the average values of CaO/REE 2O 3 (weight ratio) are 0 131 (observed) and 0 141 (calculated). Both values are lower than the ideal value 0 171 of parisite. On the basis of stoichiometrically collinear relationship, this suggests that the activities of Ca 2+ and CO 2- 3 in the parent fluid were too low to be favor to the formation of typical parisite. It can be inferred that the new polysomes in the deposit have the chemical composition within the range.

关 键 词：稀土 化学成分 氟碳铈矿-新奇钙铈矿系列 钙稀土氟碳酸盐多体矿物 成因 结构 

分 类 号：P578.6[天文地球—矿物学] P574.2[天文地球—地质学]