2月25日,，美國《國家科學(xué)院院刊》(PNAS,，2008年第9期)刊登了一篇中美科學(xué)家共同完成的,，題為“埃迪卡拉系陡山沱組幕次性氧化作用和生物演化”的研究成果。該研究從陡山沱組穩(wěn)定碳,、硫同位素的變化角度出發(fā),，揭示了埃迪卡拉紀(jì)早中期海洋和大氣中發(fā)生的氧化事件，并結(jié)合我國華南陡山沱組的化石記錄,，認(rèn)為氧化事件與生物演化事件關(guān)系密切,。中科院南京古生物所客座研究員肖書海博士，以及該所周傳明和袁訓(xùn)來研究員參加了該項研究,。
生物谷推薦原始出處:
（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.
