2月25日，美国《国家科学院院刊》(PNAS，2008年第9期)刊登了一篇中美科学家共同完成的，题为“埃迪卡拉系陡山沱组幕次性氧化作用和生物演化”的研究成果。该研究从陡山沱组稳定碳、硫同位素的变化角度出发，揭示了埃迪卡拉纪早中期海洋和大气中发生的氧化事件，并结合我国华南陡山沱组的化石记录，认为氧化事件与生物演化事件关系密切。中科院南京古生物所客座研究员肖书海博士，以及该所周传明和袁训来研究员参加了该项研究。
生物谷推荐原始出处:
（PNAS），doi：10.1073/pnas.0708336105，Kathleen A. McFadden，Shuhai Xiao
Pulsed oxidation and biological evolution in the Ediacaran Doushantuo Formation
Kathleen A. McFadden, Jing Huang, Xuelei Chu,, Ganqing Jiang,, Alan J. Kaufman, Chuanming Zhou, Xunlai Yuan, and Shuhai Xiao,
Department of Geosciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061; Key Laboratory of Mineral Resources, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China; Department of Geoscience, University of Nevada, Las Vegas, NV 89154; Department of Geology, University of Maryland, College Park, MD 20742; and State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China
Edited by Paul F. Hoffman, Harvard University, Cambridge, MA, and approved January 9, 2008 (received for review September 5, 2007)
Abstract
Recent geochemical data from Oman, Newfoundland, and the western United States suggest that long-term oxidation of Ediacaran oceans resulted in progressive depletion of a large dissolved organic carbon (DOC) reservoir and potentially triggered the radiation of acanthomorphic acritarchs, algae, macroscopic Ediacara organisms, and, subsequently, motile bilaterian animals. However, the hypothesized coupling between ocean oxidation and evolution is contingent on the reliability of continuous geochemical and paleontological data in individual sections and of intercontinental correlations. Here we report high-resolution geochemical data from the fossil-rich Doushantuo Formation (635–551 Ma) in South China that confirm trends from other broadly equivalent sections and highlight key features that have not been observed in most sections or have received little attention. First, samples from the lower Doushantuo Formation are characterized by remarkably stable 13Corg (carbon isotope composition of organic carbon) values but variable 34SCAS (sulfur isotope composition of carbonate-associated sulfate) values, which are consistent with a large isotopically buffered DOC reservoir and relatively low sulfate concentrations. Second, there are three profound negative 13Ccarb (carbon isotope composition of carbonate) excursions in the Ediacaran Period. The negative 13Ccarb excursions in the middle and upper Doushantuo Formation record pulsed oxidation of the deep oceanic DOC reservoir. The oxidation events appear to be coupled with eukaryote diversity in the Doushantuo basin. Comparison with other early Ediacaran basins suggests spatial heterogeneity of eukaryote distribution and redox conditions. We hypothesize that the distribution of early Ediacaran eukaryotes likely tracked redox conditions and that only after 551 Ma (when Ediacaran oceans were pervasively oxidized) did evolution of oxygen-requiring taxa reach global distribution.
