贵州瓮安夏安灯影组磷块岩稀土元素地球化学特征  

REE Geochemistry of the Dengying Formation Phosphorites in the Xia'an Area,Weng'an County,Guizhou Province

作　　者：丁亚龙[1] 谢宏[1] 

机构地区：[1]贵州大学资源与环境工程学院,贵州贵阳550003

出　　处：《地质与勘探》2015年第5期923-931,共9页Geology and Exploration

基　　金：贵州省地勘基金(编号:黔财建[2011]114号);贵州大学创新基金"研理工2015066"联合资助

摘　　要：贵州瓮安夏安灯影组叠层石磷块岩丰富,本文利用地球化学方法对灯影组含磷岩系稀土元素含量进行了测试分析。结果表明,矿层中上部叠层石磷块岩稀土元素总量ΣREE低,且比矿层底部砂屑磷块岩的更低,显示出明显的生物成因特点;磷块岩北美页岩组合样标准化曲线形态上近似于"帽状",也指示生物有机质参与了成磷作用。样品具有较低的稀土元素总量ΣREE、较小的LREE/HREE比值、明显的负Ce异常,普遍的正Eu异常,暗示该区磷矿为非正常海水沉积成因。因此,夏安灯影组磷矿为生物成矿与热水沉积共同作用的结果;同时,样品Ceanom值皆小于-0.1,说明夏安灯影组磷块岩形成于相对氧化的环境。There exist abundant phosphorites in the Dengying Formation of the Xia＇an area,Weng＇an County,Guizh ou Province. Geochemical analysis of REE elements has been conducted to the phosphorus rock series in this area. The results show low ΣREE values of the middle and upper deposit,even much lower than the bottom,suggesting a biogenic feature. The PAAS normalized REE concentrations plotted against respective atomic numbers form approximate the hat-shaped REE pattern,which indicates that fauna played an important role in the phosphorite formation. On the other hand,the phosphorite characters of positive Eu anomalies,the negative Ce anomalies,the low ΣREE and the low ratio of ΣLREE to ΣHREE suggest that the Xia＇an phosphorite belongs to the abnormal marine deposition. Therefore,the formation of Xia＇an phosphorite is the product of biomineralization plus hydrothermal deposition. At the same time,the results of Ceanomare all less than- 0. 1,implying a relatively oxidizing environment for formation of Xia＇an phosphorite.

关 键 词：稀土元素 叠层石磷块岩 灯影组 夏安 贵州 

分 类 号：P532[天文地球—古生物学与地层学] P566[天文地球—地质学]