贵州织金含稀土磷矿床的Sm-Nd同位素年龄及其地质意义  

Samarium-Neodymium Radiometric Dating and Its Geologic Implication of the Zhijin REE-Bearing Phosphorites,Guizhou Province,Southwest China

作　　者：施春华[1] 胡瑞忠[2] 

机构地区：[1]浙江林学院旅游与健康学院,浙江临安311300 [2]中国科学院地球化学研究所矿床地球化学国家重点实验室,贵州贵阳550002

出　　处：《地球科学（中国地质大学学报）》2008年第2期205-209,共5页Earth Science-Journal of China University of Geosciences

基　　金：中国科学院知识创新工程重要方向项目(NoKZCX3-SW-125);浙江林学院科学研究发展基金项目(No2351000584)

摘　　要：为探讨贵州织金含稀土磷矿床的形成时间和成矿物源,利用Sm-Nd同位素稀释法对该矿床磷块岩中6个小壳化石及胶磷矿样品进行了年龄测定.样品的质谱分析测试结果显示,样品的147Sm/144Nd与143Nd/144Nd构成了一条相关性良好的线性等时线;计算结果表明织金含稀土磷矿床具有533±22Ma的Sm-Nd等时年龄,εNd(t)值为-2.44～-2.77,表明它们具有相同的成因和相近的形成时代,本次测得年龄代表着真实的成矿年龄;二阶段Nd的模式年龄为1313～1338Ma.结合前人对该矿床稀土元素地球化学的研究成果表明,织金含稀土磷矿床的成矿物源有新生地幔物质组分的加入.In order to discuss the age and the provenance of the Zhijin REE-bearing phosphorites in Guizhou, six small shell fossils and cellophane sampled from the phosphorites are dated by Sm-Nd isotopic dilution method. The results of mass spectrographic analysis show that the value of ^147Sin/^144Nd and ^143 Nd/^144 Nd formed an isochronal line. The test shows that the Sm-Nd isochronal dating of Zhijin REE-bearing phosphorites is 533±22 Ma （MSWD= 1.1 ）. The εNd（t） of the samples are about -2.44 to -2.77, and the Nd two-stage model ages （T2DM） are 1 313-1 338 Ma. This result suggests that the samples have the same genesis and the approximative age, and the age represents the true mineralogenetic epoch. Combined with the REE geochemistry the juvenile mantle is responsible to the provenance of the Zhijin REE-bearing phosphorites.

关 键 词：SM-ND同位素定年 含稀土磷矿床 贵州织金 

分 类 号：P597[天文地球—地球化学]