• 责任者：Cui Hao (State Key Laboratory of Biological and Environmental Geology ; China University of Geosciences ; Wuhan 430074 ; China) ; Zhou Lian
• 刊名：Advances in Earth Science
• 出版年：2013
• 卷期：28(9)
• 关键词：古海洋学 ; paleooceanography ; 铁同位素 ; iron isotopes ; 钼同位素 ; molybdenum isotopes
• 页码：p.1049-1056
• 图表：3 illus., 2 tables, 58 refs.
• 分类号：0200
• issnNo：ISSN1001-8166
• isbnNo：CN62-1091/P

     Iron （Fe） seawater. Due to their hi as well as variations have  is abundant in nature while molybdenum （Mo） is the most abundant transition metal in gh sensitivity to the redox state of the environment, the isotopic compositions of Fe and Mo been widely used to probe the redox conditions and the evolution of ancient oeean chemis- try in favor of improved analytical techniques. Here, we summarized isotopic fractionation mechanisms and natural distribution of both iron and molybdenum isotopes, and further we summarized and partially reinterpreted the redox evolution of ancient oceans through time based on available Fe-Mo data compiled in this study. The process that causes the largest iron isotope fractionation is redox reaction and the iron in oxidation state is generally enriched in 56Fe. Biotic and abiotic pyrite formations also produce a large Fe isotope fractionations. Isotopic fractionation of mo- lybdenum in seawater is mainly caused by the adsorption process of dissolved Mo onto ferromanganese oxides or hy- droxides in sediments. Fe-Mn （hydro）oxides tend to adsorb isotopically light molybdenum resulting in the isotopic composition of Mo in seawater heavier. However, the Mo sinks in euxinic settings cause almost no molybdenum iso- tope fractionation. Tile Fe-Mo isotope isotopic records through geological timegenerally suggest similar ocean redox evolution： Oceans older than 2.3 Ga was mainly dominated by ferruginous condition, and there was a slight in- crease in oxygen content between 2.6 and 2.5 Ga. Earth＇ s surface was initially oxidized during 2.3 to 1.8 Ga, during which euxinic deposition of sulfide was elevated. Euxinic waters may have expanded greatly between 1.8 and O. 8 Ga, and after that, Earth＇ s surface had being gradually oxidized and the euxinic waters shrank substantially. Finally, suggestions are proposed for further work on the Fe-Mo isotope research in the context of ancient ocean chemistry.