Hydrothermal Bacterial Biomineralization: Potential Modern-Dayanalogues Forbandediron-Formations
Published:January 01, 2000
Kurt. O Konhauser, 2000. "Hydrothermal Bacterial Biomineralization: Potential Modern-Dayanalogues Forbandediron-Formations", Marine Authigenesis: From Global to Microbial, Craig R. Glenn, Liliane Prévôt-Lucas, Jacques Lucas
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Precambrian banded iron-formations (BIPs) are chemical sediments of hydrothermal origin and consist of Fe-rich minerals with alternating layers of chert. Because microorganisms potentially played a role in their precipitation, the study of bacterial-mineral interactions at modern hydrothermal environments may provide small-scale analogues to those conditions under which they accumulated. Interestingly, microbial populations currently growing at hot springs and deep-sea vents are commonly encrusted in iron and silicate minerals. Iron biomineralization occurs either passively through interaction between the reactive sites of the cell and dissolved cationic iron from the hydrothermal fluid, or actively through chemolithotrophic iron-oxidation by bacteria such as Gallionella genera. Amorphous silica precipitates on individual bacteria through hydrogen bonding between hydroxy groups in the extracellular polymers and hydroxyl groups in dissolved silica, with some colonies becoming completely cemented together within a siliceous matrix up to several micrometers thick. Iron-silicates form due to reactions between dissolved silica and cell-bound iron. In these predominantly nonspecific processes, bacterial cells simply catalyze reactions that are rendered possible by the supersaturated conditions created by the sudden physical and chemical changes induced through venting. Diagenetic reactions, some of which are also catalyzed by microorganisms growing in the sediment, can further alter the mineralogy of these primary precipitates, leading to the formation of secondary magnetite and siderite. In this way, all of the main mineralogical components of BIFs can be associated with microbial activity.
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Marine Authigenesis: From Global to Microbial
This volume is a collection of 33 state-of-the-art papers focusing on various aspects of authigenic and diagenetic marine minerals and related global elemental cycling. The commingling of the various studies of authigenic minerals in this volume, including the most recent advances in knowledge concerning the occurrence and origins of phosphorites, glauconites, dolomites, siderites, manganese-iron associations, barites, ironstones, and other marine chemical sediments/sedimentary rocks of early authigenic/diagenetic origin, is partly the result of the increasing awareness that there are many overlaps, even direct co-associations, between different authigenic minerals, both in time, space, and genesis. Taken together, this compilation represents a holistic approach towards marine authigenesis that considers the integrated whole more than the simple sum of its parts.