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新元古代陡山沱组-灯影组中C-Sr同位素演化及其古环境意义
Variations of C-Sr Isotopes in Neoproterozoic Doushantuo-Dengying Formation:Implications for Paleoenvironmental Change
【作者】 陈曦; 凌洪飞; 潘家永; 陈永权; 冯洪真; 蒋少涌;
【Author】 CHEN Xi LING Hongfei PAN Jiayong CHEN Yongquan FENG Hongzhen JIANG Shaoyong State Key Laboratory of Mineral Deposits Research , Nanjing University, Nanjing, Jiangsu , 210093
【机构】 南京大学内生金属矿床成矿机制研究国家重点实验室;
【摘要】 碳酸盐岩中碳同位素组成的演化对于古环境研究有重要意义。笔者研究了浙江煤山剖面的新元古代地层陡山沱组和灯影组中δ13C,δ18O,87Sr/86Sr以及微量元素含量的演化。
【Abstract】 The evolution of δ13C, δ18O,87Sr/86Sr and trace elements contents in Neoproterozoic Doushantuo Formation and Dengying Formation of Zhejiang Province was studied. It is held that 87Sr/86Sr ratios have been modified by diagenesis. Most of the samples recorded primary C isotope compositions. The extremely low S C values of the cap carbonate might have resulted from several factors. As the organic productivity, the CO2 concentration in atmosphere and the ocean circulation recovered after the Snowball Earth event, δ13C steadily shifted to normal positive values in the main Doushantuo periods. After the withdraw of a large amount of CO2 from the atmosphere as a result of weathering and organic carbon burial, the climate became cool, which induced thermohaline circulation and led to the upwelling of deep ocean water rich in 12C. These factors caused the negative excursion of δ13C along the Doushantuo-Dengying boundary and increased the CO2 concentration in the atmosphere to a normal level. During most time of the Dengying period, the oceanic and climatic conditions were kept in a state favoring the ecosystem, yielding positive δ13C values in most part of the Dengying Formation.
【Key words】 carbon isotope carbonate paleoenvironment change Neoproterozoic Zhejiang;
- 【会议录名称】 第八届全国同位素地质年代学、同位素地球化学学术讨论会资料集
- 【会议名称】第八届全国同位素地质年代学、同位素地球化学学术讨论会
- 【会议时间】2005-10
- 【会议地点】中国南京
- 【分类号】P597;P531
- 【主办单位】中国矿物岩石地球化学学会、中国地质学会