The geomicrobiology of bauxite deposits  

作　　者：Xiluo Hao Kwunlun Leung Rucheng Wang Weidong Sun Yiliang Li 

机构地区：[1]Key Laboratory of Isotope Geochronology and Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences,Guangzhou 510640, China [2]Department of Earth Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China [3]Graduate School of the Chinese Academy of Sciences, Beijing 100039, China [4]School of Geological Sciences ＆ Engineering, Nanjing University, Nanjing 210093, China

出　　处：《Geoscience Frontiers》2010年第1期81-89,共9页地学前缘（英文版）

基　　金：supported by the Hong Kong University General Research Fund HKU703008P on‘Planetary Evolution of Ferric Iron Metabolism

摘　　要：Bauxite deposits are studied because of their economic value and because they play an important role in the study of paleoclimate and paleogeography of continents. They provide a rare record of the weathering and evolution of continental surfaces. Geomicrobiological analysis makes it possible to verify that microorganisms have played a critical role during the formation of bauxite with the possibility already intimated in previous studies. Ambient temperature, abundance of water, organic carbon and bioavailable iron and other metal substrates provide a suitable environment for microbes to inhabit. Thiobacillus, Leptospirilum, Thermophilic bacteria and Heterotrophs have been shown to be able to oxidize ferrous iron and to reduce sulfate-generating sulfuric acid, which can accelerate the weathering of aluminosilicates and precipitation of iron oxyhydroxides. Microorganisms referred to the genus Bacillus can mediate the release of alkaline metals. Although the dissimilatory iron-reducing and sulfate-reducing bacteria in bauxites have not yet been identified, some recorded authigenic carbonates and ＂bacteriopyrites＂ that appear to be unique in morphology and grain size might record microbial activity. Typical bauxite minerals such as gibbsite, kaolinite, covellite, galena, pyrite, zircon, calcium plagioclase, orthoclase, and albite have been investigated as part of an analysis of microbial mediation. The paleoecology of such bauxitic microorganisms inhabiting continental （sub） surfaces, revealed through geomicrobiological analysis, will add a further dimension to paleoclimatic and paleoenvironmental studies.Bauxite deposits are studied because of their economic value and because they play an important role in the study of paleoclimate and paleogeography of continents. They provide a rare record of the weathering and evolution of continental surfaces. Geomicrobiological analysis makes it possible to verify that microorganisms have played a critical role during the formation of bauxite with the possibility already intimated in previous studies. Ambient temperature, abundance of water, organic carbon and bioavailable iron and other metal substrates provide a suitable environment for microbes to inhabit. Thiobacillus, Leptospirilum, Thermophilic bacteria and Heterotrophs have been shown to be able to oxidize ferrous iron and to reduce sulfate-generating sulfuric acid, which can accelerate the weathering of aluminosilicates and precipitation of iron oxyhydroxides. Microorganisms referred to the genus Bacillus can mediate the release of alkaline metals. Although the dissimilatory iron-reducing and sulfate-reducing bacteria in bauxites have not yet been identified, some recorded authigenic carbonates and ＂bacteriopyrites＂ that appear to be unique in morphology and grain size might record microbial activity. Typical bauxite minerals such as gibbsite, kaolinite, covellite, galena, pyrite, zircon, calcium plagioclase, orthoclase, and albite have been investigated as part of an analysis of microbial mediation. The paleoecology of such bauxitic microorganisms inhabiting continental （sub） surfaces, revealed through geomicrobiological analysis, will add a further dimension to paleoclimatic and paleoenvironmental studies.

关 键 词：GEOMICROBIOLOGY BAUXITE Microbial activity Microbial-mediated release of elements Biomineralization 

分 类 号：P618.450.8[天文地球—矿床学] TE132.4[天文地球—地质学]