贵州石炭系“清镇式”铁矿沉积地球化学特征  

Sediment Geochemical Character of Carboniferous "Qingzhen-type Fe Deposit" in Central Guizhou Area

作　　者：杨瑞东[1] 袁世婷[1] 魏怀瑞[1] 陈吉艳[1] 程玛莉[1] 

机构地区：[1]贵州大学,贵阳550004

出　　处：《地质论评》2011年第1期24-35,共12页Geological Review

基　　金：贵州大学矿床学博士点基金资助项目的成果

摘　　要：贵州中部清镇、修文、开阳等地石炭系铝土矿底部的铁矿被称为"清镇式铁矿",铁矿层被认为是湖泊沉积产物。笔者等对其地质地球化学研究发现,清镇林歹、卫城和龙里长冲等地"清镇式铁矿"的铁质岩主要由赤铁矿、菱铁矿组成;在清镇含铁岩系中稀土元素具有较高的富集,ΣREE75.71×10-6～859.45×10-6,铁质岩中Zr、Ga、Ge、Sc、Ti元素富集,其中金属Sc含量在20×10-6左右,具有开发利用价值。铁质岩的Sr/Ba值均大于1,Th/U值在2～7之间,与二叠系山西式铁矿类似,表明铁质岩沉积受到海水的影响,是潟湖环境下沉积的产物。稀土球粒陨石标准化曲线具有强烈的Eu负异常和Ce弱负异常。清镇式铁矿菱铁矿δ13CPDB为-3.21‰～-7.24‰,比其他沉积型、沉积变质型铁矿低。The Fe-bearing rocks under bauxite bed in Qingzhen,Xiuwen and Kaiyang Counties,Guizhou Province,was called as ＂Qingzhen-type Fe deposit＂,and considered lacustrine deposit. Writers discover with sedimentary geological,mineral association and geochemical study that the iron ores of ＂Qingzhen-type Fe deposit＂ in Lindai and Weicheng,Qingzhen City,Changchong,Longli County,consists of hematite and siderite; the Fe-bearing rocks are riched in rare earth element and trace element Zr,Ga,Ge,Sc,Ti,ΣREE from 75.71 to 859.45×10^-6,Sc are up to 20×10^-6,which are of very important value in economic; all Sr/Ba ratio values of Fe-bearing rocks are 1,Th/U ratio values are 2 to 7,similar to those of the ＂Shanxi-type iron deposit＂,which suggests that the Fe-bearing rocks formed in lagoon and affected by sea water. Chondrite-normalized rare earth element patterns of the Qingzhen-type Fe deposit show that Eu is remarkable negative anomaly and Ce is weak negative anomaly. The δ^13C PDB values of siderite are-3.21‰--7.24‰,lower than those values of other sediment-type Fe deposit and sediment metamorphic–type Fe deposit.

关 键 词：沉积环境 地球化学 铁矿 石炭系 贵州 

分 类 号：P595[天文地球—地球化学]