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.
出处
《沉积学报》
CAS
CSCD
北大核心
2008年第1期1-10,共10页
Acta Sedimentologica Sinica
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
rare earth element, positive europium anomaly, hydrothermal activity, lacusrine carbonate, Cenozoic, Tibetan Plateau
