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The geomicrobiology of bauxite deposits

Geoscience Frontiers 2010年第1期1卷 81-89页

作者： Xiluo Hao Kwunlun Leung Rucheng Wang Weidong Sun Yiliang Li Key Laboratory of Isotope Geochronology and Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of SciencesGuangzhou 510640 China Department of Earth Sciences The University of Hong Kong Pokfulam Road Hong Kong China Graduate School of the Chinese Academy of Sciences Beijing 100039 China School of Geological Sciences ＆ Engineering Nanjing University Nanjing 210093 China

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

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Bio-Organic Geochemistry research in China: Advances,opportunities and challenges

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Science China Earth Sciences 2018年第12期61卷 1775-1780页

作者： Chuanlun ZHANG Ping'an PENG Meixun ZHAO Shucheng XIE Jianfang CHEN Weiguo LIU Shenzhen Key Laboratory of Marine Archaea Geo-Omics Department of Ocean Science and EngineeringSouthern University of Science and Technology Laboratory for Marine Geology Qingdao National Laboratory for Marine Science and Technology State Key Laboratory of Organic Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences Key Laboratory of Marine Chemistry Theory and Technology (Ocean University of China) Ministry of Education/Laboratory for Marine Ecology and Environmental Science Qingdao National Laboratory for Marine Science and Technology State Key Laboratory of Biogeology and Environmental Geology School of Earth Sciences China University of Geosciences Key Laboratory of Marine Ecosystem and Biogeochemistry State Oceanic Administration State Key Laboratory of Loess and Quaternary Geology Institute of Earth EnvironmentChinese Academy of Sciences

The discipline of "Bio-Organic Geochemistry" is a cross research field between biogeochemistry and traditional organic geochemistry, which focuses on geochemical processes related to the biosynthesis of organic molecules(particularly lipids) by(micro) organisms, organic matter production by primary producers, degradation of organic matter by microbial processes recorded by retainable lipid biomarkers, and organic proxies for studies of paleo-climate, paleo-environments, paleoecology and Earth evolution. This field aims to go beyond the traditional petroleum-oriented Organic Geochemistry by integrating with biogeochemical concepts concerned mostly with biomolecules from cellular material such as DNA and lipids. A formal Chinese organization in Bio-Organic Geochemistry was established in 2012 when the first conference was held in Guangzhou. This organization has witnessed rapid growth over the past six years with focused research addressing organic proxies in paleoclimate and paleoenvironmental applications, with particular rapid development in glycerol dialkyl glycerol tetraethers-derived proxies. Most progresses in China so far are made following or paralleling the international trend in biogeochemical studies. Things have begun to change with China's ambitious initiatives in several bio-geo programs such as the Ocean Deep Drilling Program of China, the Microbial Hydrosphere Program, the Deep Carbon Observatory, and the Microbiome Program. Looking forward in the 21 st Century, the growing Chinese research community in Bio-Organic Geochemistry faces grand opportunities and challenges as Chinese scientists propel themselves toward global research frontiers.

关键词： Bio-Organic Geochemistry Biogeochemistry geomicrobiology Paleoclimate proxies Carbon cycles Microbial genomics

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Types and microbial genesis of carbonate microbodies in Zoophycos from the Pennsylvanian to Cisuralian Taiyuan Formation in North China

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Journal of Palaeogeography 2018年第3期7卷 283-294页

作者： Hui-Bo Song Xiang-Yu Zhang Shun-Xi Liu Bin hu Rui-Rui Guo Yu-Jun Bi School of Resource and Environment Henan Polytechnic UniversityJiaozuo 454000Henan ProvinceChina. Collaborative Innovation Center of Coalbed Methane and Shale Gas for Central Plains Economic Region of Henan Province Jiaozuo 454000Henan ProvinceChina. Key Laboratory of Biogenic Traces and Sedimentary Minerals of Henan Province Jiaozuo 454000Henan ProvinceChina. Coal Mining and Dressing Department Changzhi Polytechnic CollegeChangzhi 046000Shanxi ProvinceChina.

Many kinds of ichnofossil Zoophycos occur commonly in the carbonate rocks of Pennsylvanian to Cisuralian Taiyuan Formation in North China. In this study, carbonate microbodies types were identified in four differently-colored fillings of Zoophycos using scanning electron microscopy （SEM） and energy dispersive spectroscopy （EDS）. Based on the morphologic characteristics, these carbonate microbodies can be divided into three groups, i.e., spheroids, framboids and rhabditiforms. According to the structural features of surface and individual or aggregate morphologies, the three groups can be further subdivided into thirteen types：（1） smooth spheroids; （2） spheroids with tiny thorns; （3） spheroids with a finely granulated surface; （4） spheroids with a flocculent surface; （5） spheroids with a vermiform surface; （6） framboid monomers; （7） framboid colonies; （8） linear smooth rhabditiform bodies; （9） smooth rhabditiform bodies with expanding ends; （10） biserial rhabditiform bodies; （11） spiral rhabditiform bodies; （12） thorny rhabditiform bodies; and （13） branched rhabditiform bodies. This paper not only describes the morphology, composition and occurrence of the various carbonate microbodies, but also discusses their possible microbial genesis, as follows：（1） carbonate spherical microbodies most likely were generated after globular bacterial cells had been fully displaced by minerals; （2） framboid monomers and colonies corresponding to the morphology of biogenic strawberry （or raspberry） pyrite, with their appearance and internal structure possibly inheriting the morphology of microbial cells, were indirectly generated by some microenvironmental changes due to microbial activity; （3） the morphological features, size, occurrences and preservation of filamentous and rhabditiform microbodies indicate that they may be biogenic structures, and possibly mineralized microbial fossils; and （4） some kind of symbiotic relationship exists between microbial action and the Zoophycos

关键词： geomicrobiology Carbonate microbodies Taiyuan Formation Trace fossil Zoophycos North China

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