Geochemistry of the Middle to Late Permian limestones from the marginal zone of an isolated platform(Laibin,South China)
  • 【摘要】

    Major,trace and rare earth elements were measured in 27 samples of the Middle to Late Permian limestones from the Tieqiao section located on the marginal zone of an isolated platform(Laibin,South Chin... 展开>>Major,trace and rare earth elements were measured in 27 samples of the Middle to Late Permian limestones from the Tieqiao section located on the marginal zone of an isolated platform(Laibin,South China).Shale-normalized REE+Y patterns of all samples show notably negative Ce anomalies(0.21–0.66,average 0.33),slightly positive Gd anomalies(1.08–1.30,average1.20),and positive Y anomalies with superchondritic Y/Ho ratios(36–91,average 55),which are consistent with those of modern shallow seawater.Their relative LREEs enrichment with higher NdSN/YbSN ratios(0.58–1.80)than those of modern shallow seawater(0.21–0.50)suggests complicated sources of REEs for all samples.Compared with geochemical features of sediments influenced by terrigenous particles and hydrothermal fluids,it is concluded that ambient shallow seawater was the primary source of REEs in these limestones.Comparing the indicators of REE+Y elements(REE,NdSN/YbSN,Ce/Ce*,Gd/Gd*,Eu/Eu*and Y/Ho)in limestones with those in bedded cherts from the Tieqiao section,we consider that limestone and bedded chert have similar sources of REE+Y elements:ambient shallow seawater with more or less hydrothermal fluids.In addition,there is a completely negative correlation between CaCO3and SiO2contents in limestones and bedded cherts.These results imply that precipitation of CaCO3was inhibited by that of SiO2which was derived mainly from hydrothermal fluid,especially in bedded cherts from the Tieqiao section. 收起<<

  • 【作者】

    QIU Zhen  WANG QingChen  YAN DeTian 

  • 【作者单位】

    State Key Laboratory of Lithospheric Evolution/PetroChina Research Institute of Petroleum Exploration and Development/Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education

  • 【刊期】

    中国科学:地球科学(英文版) EI SCI 2013年10期

  • 【关键词】

    geochemistry  rare earth element  limestone  the Middle to Late Permian  South China  geochemistry  rare earth element  limestone  the Middle to Late Permian  South China 

  • 【基金项目】

    financially supported by the National S&T Major Project(Grant No.2011ZX05008) National Natural Science Foundation of China(Grant Nos.41273001and41103018)