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[1] 凌洪飞[1] 潘家永[1] 陈永权[1] 冯洪真[1] 蒋少涌[1] 

机构地区：[1]南京大学内生金属矿床成矿机制研究国家重点实验室,江苏南京210093

出　　处：《地球学报》2005年第B09期197-197,共1页Acta Geoscientica Sinica

基　　金：本研究得到国家自然科学基金项目（编号：40232020,40172041）资助.

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δ^13C，δ^18O,^87Sr/^86Sr以及微量元素含量的演化。The evolution of δ^13C, δ^18O, ^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 δ^13C 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, δ^13C 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 δ^13 C 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 δ^ 13C values in most part of the Dengying Formation.

关 键 词：碳同位素 碳酸盐 古环境变化 新元古代 浙江 同位素演化 陡山沱组 灯影组 古环境意义 碳同位素组成 

分 类 号：P588.245[天文地球—岩石学] Q913.63[天文地球—地质学]