西藏高原沱沱河盆地渐新世-中新世湖相碳酸盐岩稀土元素地球化学特征与正铕异常成因初探  

Geochemistry of Rare Earth Elements and Origin of Positive Europium Anomaly in Miocene-Oligocene Lacustrine Carbonates from Tuotuohe Basin of Tibetan Plateau

作　　者：伊海生[1] 林金辉[2] 赵西西[3] 周恳恳[1] 李军鹏[1] 黄华谷[1] 

机构地区：[1]成都理工大学沉积地质研究院,成都610059 [2]成都理工大学材料与化学化工学院,成都610059 [3]美国加利福尼亚大学,圣克鲁斯CA95064

出　　处：《沉积学报》2008年第1期1-10,共10页Acta Sedimentologica Sinica

摘　　要：对采自沱沱河盆地通天河剖面渐新世雅西措群和中新世五道梁群地层中的湖相灰岩和白云岩样品进行了稀土元素和微量元素分析。研究结果表明,湖相碳酸盐岩稀土元素总量(∑REE)变化于36.23×10-6～189.64×10-6,28件样品平均值为78.58×10-6。稀土元素的页岩标准化配分形式具有中组稀土富集的特点,正铕异常极为明显,在渐新统与中新统界线处Eu/Eu*比达到最大值7.15,这也是首次在陆地湖泊沉积记录中观察到的正Eu异常。根据稀土元素的分布以及Eu与Ba含量的同步变化特点,提出该区湖相碳酸盐岩中Eu的异常富集可能与湖底喷流热水有关。The concentrations of rare earth elements （REE） and trace elements were analysed Miocene-Oligocene lacustrine carbonates collected in the Tongtianhe section of Tuotuohe Basin of Tibetan Plateau. The total REE contents（ ∑REE） of lacustrine limestone and dolostones covers a wide range：36.23 ×10^-6-189.64 ×10^-6 and its average value of 28 samples is 78.58×10^-6. The shale-normalized REE patterns display middle REE enrichments and strong positive Eu anomalies. The relatively high Eu/Eu ^＋ ratios occur across the Oligocene and Miocene boundary layers. This is the first report of positive Eu anomalies observed in REE patterns in terrestrial sediment records. Based on REE distributions and covariance between Eu and Ba, this paper presents Eu anomaly in lacustrine carbonate samples of the study area implies hydrothermal venting occurrence in paleolake systems.

关 键 词：稀土元素 正铕异常 热水沉积 湖相碳酸盐岩 新生代 西藏高原 

分 类 号：P595[天文地球—地球化学]