Organo-mineral structures, biominerals, and exceptional fossil preservation---a microcosm of the influence of iron-oxidizing microbes on the fossil recordg

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Proceedings of the Geological Society of America Annual Meeting


The expanding role microbes play in the authigenesis and dissolution of minerals can in the right environmental circumstances be extensive and significant. This geomicrobial significance is on full display in recently discovered exceptionally preserved fossils from the Ediacaran-Cambrian Deep Spring Formation, Nevada. Consisting of tubicolous organisms, this fossil biota provides evidence for the influence of iron-oxidizing microbial communities in the synthesis of authigenic iron oxyhydroxide biominerals which provided a mineralogical outline of labile tissues. This mineralization likely occurred within the microaerophilic iron-oxidation zone of the sedimentary column during early stages of microbial degradation of organic matter. The authigenic precipitation of iron-rich clays also acts as the primary preservation in some specimens. An iron gradient within clays outlining tissues in these specimens provides direct evidence of the importance of the early adsorption of Fe(II) and Fe(III) ions onto structural biopolymers during soft-tissue preservation.