利用用ICP－MS研究桂林寨底地下河系统中碳酸盐岩稀土元素特征及其形成环境  

Rare Earth Element Composition of Carbonate Rocks Afforded by LA-ICP-MS and Its Formation Environment of the Zhaidi Underground River in Guilin

作　　者：樊连杰[1] 裴建国[1] 赵良杰[1] 林永生[1] 卢丽[1] 王喆[1] 

机构地区：[1]中国地质科学院岩溶地质研究所、国土资源部/广西壮族自治区岩溶动力学重点实验室,广西桂林541004

出　　处：《岩矿测试》2016年第3期251-258,共8页Rock and Mineral Analysis

基　　金：中国地质科学院岩溶地质研究所基本科研业务费项目(2014023);中国地质调查局地质调查项目(1212011121164)

摘　　要：稀土元素是研究沉积岩的形成条件及环境特征的重要指标,本文以桂林寨底地下河系统中岩石样品为研究对象,采用激光剥蚀电感耦合等离子体质谱进行稀土元素测试分析,研究了该地区碳酸盐岩的形成环境。结果表明:碳酸盐岩的稀土总量(∑REEs)偏低,不同地层岩性间的∑REEs具有一定差异性,总体上信都组泥质粉砂岩(D2x)的∑REEs最高,其次为融县组(D3r)厚层灰岩和桂林组灰岩(D3g),东村组厚层灰岩(D3d)和额头村组灰岩及白云质灰岩(D3e)的∑REEs较低。整体上表现为重稀土元素相对于轻稀土元素富集的特征,且Ce具有较明显的负异常,而Eu无异常或异常不明显,不同于碎屑岩的轻稀土相对富集、Eu负异常、Ce无异常或异常不明显的特征。这些特征表明研究区碳酸盐岩的形成环境为氧化-海相碳酸盐岩沉积环境,可为定量化判别岩溶区碳酸盐岩形成环境提供依据。Rare earth elements are an important indicator for studying the formation condition and environmental characteristics of sedimentary rocks. The REEs of limestone samples in the Zhaidi underground river in Guilin were determined by Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry( LA-ICP-MS) and the formation environment is discussed in this paper. Results show that the total rare earth elements( REEs) content of carbonate rocks is low. There are differences in the concentrations of rare earth elements for carbonate rocks of different strata. Total REEs( ΣREEs) of sandstone in Xindu formation is the highest,followed by thick limestone of Rongxian formation( D3r) and limestone of Guilin formation( D3g). Thick-layer limestone of Dongcun formation( D3d) and limestone and dolomite limestone of Etoucun formation( D3e) contain low REEs. In general,heavy rare earth elements are relatively enriched,with negative Ce anomalies and no Eu anomalies. The REE patterns of carbonate rocks are completely different from negative Eu anomalies and no Eu anomalies for clastic rock. These characteristics of rare earth elements indicate that the sedimentary environment is an oxidative marine carbonate sedimentary environment,which provides a baseline for the formation environment of carbonate rocks in the Karst region.

关 键 词：岩溶地区 碳酸盐岩形成环境 稀土元素 激光剥蚀电感耦合等离子体质谱法 

分 类 号：O657.63[理学—分析化学] P588.245[理学—化学]