河南省嵩箕地区南部铝土矿中铈正异常成因分析  

Formed Causes of Positive Ce Anomaly in Bauxite Deposits in Southern Songshan-Jishan Region,Henan Province

作　　者：蒋丽 徐伟 蒋芹 韩长寿 薛亚飞 JIANG Li;XU Wei;JIANG Qin;HAN Chang-shou;XUE Ya-fei(Mineral Resources Exploration Center of Henan Geological Bureau,Zhengzhou 450006,China;Henan Remote Sensing Intelligent Monitoring Engineering Technology Research Center for Satellite,Aircraft and Land Survey,Zhengzhou 450006,China;Henan Natural Resources Science and Technology Innovation Center,Zhengzhou 450006,China;Team 4,Henan Province Non-ferrous Metal Geological and Mineral Resources Bureau,Zhengzhou 450016,China)

机构地区：[1]河南省地质局矿产资源勘查中心,河南郑州450006 [2]河南省天空地遥感智能监测工程技术研究中心,河南郑州450006 [3]河南省自然资源科技创新中心,河南商郑州450006 [4]河南省有色金属地质矿产局第四地质大队,河南郑州450016

出　　处：《稀土》2024年第3期97-107,I0005,共12页Chinese Rare Earths

摘　　要：河南省嵩箕地区铝土矿含矿岩系中的稀土元素特征是古风化壳稀土元素富集与分布特征的反映,但其有两个特征区别于现代风化壳,一是含矿岩系中铝土矿层中δCe达到1.77,其他岩石为1.07~1.16,无负异常存在;二是含矿岩系中∑REE为398.43×10^(-6)~440.32×10^(-6),没有明显的富集层。通过不同风化壳原岩在风化过程中稀土元素地球化学行为特征的对比,认为古风化壳原岩中黄铁矿的含量决定了风化壳中pH值变化,含黄铁矿较高的铝硅酸盐岩形成的风化壳上部呈较强酸性环境,易使Ce^(4+)的络合物水解形成氢氧化物。铈氢氧化物下迁和沉淀富集造成风化壳上部稀土元素中的铈亏损,含矿岩系中没有铈负异常反映出风化壳在成矿前遭受了部分剥蚀。含矿岩系中V/Cr平均值为1.55,Co/Ni平均值0.31,显示沉积过程中海水呈氧化环境,海水中悬浮颗粒中的稀土元素可产生进一步分异,这对含矿岩系中铈正异常的形成也起一定作用。含矿岩系中稀土元素在成矿后未发生明显变化。The characteristics of rare earth elements in bauxite ore-hosted strata in Songshan-Jishan region of Henan Province are the reflection of the enrichment and distribution of REE in paleo-weathered crust,but there are two characteristics that are different from present weathered crust.Firstly,the δCe in the bauxite reaches 1.77,and 1.07~1.16 for other rocks.There is no negative anomaly.Secondly,theΣREE in the ore-hosted strata is 398.43×10^(-6)~440.32×10^(-6),there is no obvious enrichment layer.Comparison of the geochemical behavior characteristics of rare earth elements in the weathering process,it is believed that the content of pyrite in the paleo-weathered crust original rocks determines the pH change in the weathered crust,the upper part of the weathered crust formed by aluminosilicate rocks containing high pyrite is in a strong acidic environment,the Ce^(4+)complex compound is easily hydrolyzed to form a hydroxide.The downward migration and deposition of Ce hydroxide resulted in the loss of Ce in upper part of the weathered crust,so the absence of negative Ce anomaly in the ore-hosted strata reflects that the weathered crust had been denuded partly before mineralization.In bauxite ore-hosted strata,the average value of V/Cr is 1.55 and Co/Ni is 0.31,which shows that the seawater has an oxidizing environment during the deposition process,and REE in the suspended particles in the seawater can be further separated,which also has a certain effect in the formation of the positive Ce anomaly in bauxite ore-hosted strata.REE in the ore-hosted strata didn′t change significantly after mineralization.

关 键 词：嵩箕地区 古风化壳 铝土矿 稀土元素 铈正异常 

分 类 号：P595[天文地球—地球化学]