应用去除碳酸盐法研究滇黔地区“白泥塘层”硅质成分的来源  

Application of the Removing Carbonate Method to Study the Origin of Silica in 'Bainitangceng' of Yunnan-Guizhou Area

作　　者：江冉[1] 付勇[1,2] 王富良[1] 裴浩翔[2] 徐志刚[2] 温宏利[3] 周文喜[1] 

机构地区：[1]贵州大学资源与环境工程学院,贵州贵阳550000 [2]中国地质科学院矿产资源研究所,北京100037 [3]国家地质实验测试中心,北京100037

出　　处：《岩矿测试》2016年第3期236-244,共9页Rock and Mineral Analysis

基　　金：中国地质大调查项目--全国重要矿产区域成矿规律研究(1212011121037);中国分矿种(组)矿产地质总结研究(12120114039601);中国矿产地质与区域成矿规律综合研究(中国矿产地质志)(1212011220369)

摘　　要：滇黔地区的“白泥塘层”与锰矿具有密切的成因联系,前人对其地球化学特征研究时关注的主要是硅质灰岩全岩,并非硅质成分本身,而硅质岩全岩能否真实地反映“白泥塘层”中硅质的来源有待研究.本文以滇黔地区“白泥塘层”硅质灰岩为研究对象,用盐酸去除硅质灰岩中的碳酸盐矿物,获得成分较为单一的硅质组分,采用ICP-MS和ICP-OES测定全岩与去除碳酸盐的硅质组分中的微量元素,通过对比两者的微量元素地球化学特征研究“白泥塘层”中硅质的来源问题.结果表明：去除碳酸盐的硅质组分的Th/U=0.02～0.05,低于全岩的Th/U值（0.08～0.2）,Eu/Eu =0.86～1.54（均值1.15）,显示为正Eu异常,此特征不同于全岩（全岩的Eu/Eu =0.87～0.93,均值0.90,显示为弱的负Eu异常）;硅质组分及全岩的稀土含量均表现为轻稀土较重稀土富集,但硅质组分中的轻稀土所占比重大于全岩.以上特征确切地表明了“白泥塘层”硅质灰岩中的硅质成分来自于热水,对于解释二叠系时期锰矿的形成具有重要的指示意义.Bainitangceng in the Yunnan and Guizhou area has a close relationship with manganese deposits. Previous geochemical studies focused on the whole rock of siliceous limestones rather than siliceous components. The question of whether or not whole rocks can really reflect the source of siliceous components needs further study. In this study,Bainitangceng ' siliceous limestone in Yunnan and Guizhou area was selected and HCl was used to remove the carbonate minerals in siliceous limestone to acquire simple composition siliceous components. Trace elements in siliceous components were determined by ICP-MS / OES. The origin of siliceous components is discussed by comparing the trace elemental composition of the whole rock of siliceous limestone and siliceous components after removing carbonate. Results show that Th / U ratios( 0. 02- 0. 05) in siliceous components are lower than those( 0. 08- 0. 2) of the whole rock of siliceous limestone. Siliceous components after removing the carbonate minerals have Eu / Eu*values of 0. 86 to 1. 54 with positive Eu anomaly,different from Eu / Eu*values( 0. 87- 0. 93) of the whole rock of siliceous limestone with negative Eu anomaly. Both whole rock of siliceous limestone and siliceous components are characterized by enriching the light rare earth elements,but the proportion of light rare earth elements in siliceous components is larger than that in whole rock. The above characteristics indicate that the siliceous component of ‘Bainitangceng ' may have been derived from hydrothermal fluid,which is important for explaining the formation of Permian manganese deposits.

关 键 词：“白泥塘层” 硅质组分 碳酸盐矿物 热水成因 电感耦合等离子体质谱/光谱法 

分 类 号：P588.245[天文地球—岩石学] O657.63[天文地球—地质学]