摘要
针对沙子江矿床的区域地层、赋矿围岩、成矿各阶段方解石及铀矿石进行稀土元素地球化学研究发现：各类样品具大体类似的LREE富集及Eu负异常的稀土配分模式,表明它们之间稀土元素特征具有继承性,赋矿花岗岩与区域地层稀土元素特征指示两者具有共同的陆壳沉积物源区;方解石及矿石中稀土元素主要继承了赋矿花岗岩的特征。成矿各阶段方解石Y/Ho值范围狭窄,在28.86~38.22之间,显示它们具共同的源区,且从成矿早阶段经主成矿阶段到成矿晚阶段,Eu负异常趋于强烈,δEu均值由0.34→0.26→0.25,表明成矿流体向相对还原环境演化。铀矿石具最高的稀土元素总量（ΣREE=259.88×10-6~869.31×10-6）,且与铀矿石的品位存在正相关关系,暗示稀土元素与铀的迁移具同步性。铀矿石（以原生铀矿物为主）中Ce负异常的形成可能与铀源岩中分散的U（Ⅳ）被活化为在成矿流体中易迁移的U（Ⅵ）的氧化过程相伴;而铀黑的Ce正异常则是由表生作用过程所导致。
REE geochemistry of 4 groups of samples（the regional stratigraphy,ore-hosting rocks,calcites and uranium ores） were analyzed by using ICP-MS method to investigate the genesis of the Shazijiang uranium ore deposit in northern Guangxi,China.Different groups of samples show significant similarities in LREE-enriched REE patterns and negative Eu anomalies.It is indicated that ore-hosting rocks and regional strata are of common sedimentary source of the continental crust.Besides,calcites and uranium ores inherited abundant REE geochemical characteristics from ore-hosting rocks.The calcites from different mineralization stages with narrow range of Y/Ho ratios between 28.86~38.22 were the products derived from the same source.From early to main and then late mineralization stage,the growing trend of negative Eu anomalies（a decrease in the δEu values：0.34→0.26→0.25） of calcites suggests that the ore-forming fluid changed to reducing environment.In addition,uranium ores are characterized by highest ΣREE contents（ΣREE=259.88×10-6~869.31×10-6） and ΣREE contents correlating positively with uranium ores grades,which is regarded as a clue to Simultaneous transportation of REE and U.Negative Ce anomalies of uranium ores（except for two uranium black samples） were most probably resulted from oxidation condition.Meanwhile,U（Ⅳ） distributed in uranium source was oxidized to U（Ⅵ） which is easily transported in ore-forming fluid.Whereas,positive Ce anomalies of 2 uranium black samples are attributed to supergene processes.
出处
《矿物岩石》
CAS
CSCD
北大核心
2011年第1期36-42,共7页
Mineralogy and Petrology
基金
国家自然科学基金重大项目(40634020)
国家重点基础研究发展规划项目(2007CB411408)
关键词
稀土元素
地球化学
沙子江
苗儿山
桂北
REE
geochemistry
Shazijiang
Miaoershan
northern Guangxiang
