四川冕宁木落寨稀土矿床稳定同位素研究及其意义  

Stable isotope data from Muluozhai REE deposit in Mianning County, Sichuan Province, and their geological implications

作　　者：田世洪[1] 张桂兰[2] 侯增谦[1] 丁悌平[1] 谢玉玲[3] 袁忠信[1] 白鸽[1] 邹天人[1] 

机构地区：[1]中国地质科学院矿产资源研究所 [2]内蒙古自治区国土资源信息院,内蒙古呼和浩特010020 [3]北京科技大学土木与环境工程学院,北京100083

出　　处：《矿床地质》2005年第6期647-655,共9页Mineral Deposits

基　　金：国家重点基础研究发展规划项目(编号:2002CG412610和G1999043211);国家杰出青年基金(编号:40425014);中国地质科学院重点开放实验室专项资金(编号:KL05_9)联合资助

摘　　要：木落寨稀土矿床在构造上位于西南新生代陆内造山带的锦屏山北缘。文章通过对木落寨2个坑道的矿石样品的C、H、O、S同位素组成的系统研究,探讨了木落寨稀土矿床成矿流体的来源及其与深部过程的关系。研究表明,石英和萤石的δ13CV_PDB值为-2.5‰～-9.0‰,方解石、石英、萤石和氟碳铈矿的δDV_SMOW值为-63‰～-87‰,萤石和石英的δ18O水V_SMOW为10.0‰～15.5‰,重晶石和方铅矿的δ34SV_CDT值分别为0.1‰～2.2‰和-8.6‰～-9.3‰,方解石的δ13CV_PDB和δ18OV_SMOW分别为-6.6‰～-6.8‰和8.4‰～9.1‰。所有这些数据均显示木落寨稀土矿床在成矿过程中有大量地幔流体的参与,表明其成矿作用与深部过程有关。The Muluozhai REE deposit, located about 60 km southwest of Mianning County, Sichuan Province, is the third large LREE deposit in Sichuan. The Muluozhai REE deposit is tectonically located on the northern margin of the Jinpingshan Mountain in the Cenozoic intracontinental orogenic belt of southwestern China. Based on field work, the authors analyzed the essential ores from two tunnels for their carbon, hydrogen, oxygen, and sulfur isotopic components so as to investigate sources of metallogenic fluids in the Muluozhai REE deposit and the relation between the metallogenic fluids and the deep process. The δ^13Cv-PDB values of fluids from fluid inclusions in quartz and fluorite vary from -2.5 to -9.0 per mil, showing characteristics of mantle-derived carbon. The 8Dv-SMoW values of fluids from fluid inclusions in calcite, quartz, fluorite and bastnaesite range from -63 to -87 per rail, suggesting characteristics of mantle-derived hydrogen. The δ^34SV-CDT values of barite and galena vary in narrow ranges of ＋ 0.1 ～ ＋ 2.2 per mil and -8.6～-9.3 per mil, respectively, indicating isotopic characteristics of mantle-derived sulfur. The δ^13Cv-PDB values and the δ^18Cv-SMOW values of calcite range from -6.6 to -6.8 per rail and from ＋ 8.4 to ＋ 9.1 per mil, respectively, which are fallen into the range of the “primary carbonatites”, implying that carbon and oxygen in ores of Muluozhai ore veins were mainly derived from the depth. The stable isotopic data suggest a mantle source for the REE mineralization and a deep process involving mantle materials and tectonics.

关 键 词：地球化学 稀土矿床 稳定同位素 幔源 木落寨 四川冕宁 

分 类 号：P618.7[天文地球—矿床学] P597.2[天文地球—地质学]