HR: 14:55h
AN: B23G-06    [Abstracts]
TI: Microbially Mediated Glass Alteration in the Geological Record: Textural clues for Microbial Functions.
AU: * Staudigel, H
EM: hstaudigel@ucsd.edu
AF: Scripps Inst. of Oceanography, UCSD-0225, La Jolla, CA 92093-0225, United States
AU: Furnes, H
EM: Harald.Furnes@geo.uib.no
AF: University of Bergen, Allegt. 41, Bergen, 5007, Norway
AU: McLoughlin, N
EM: Nicola.Mcloughlin@geo.uib.no
AF: University of Bergen, Allegt. 41, Bergen, 5007, Norway
AU: Banerjee, N
EM: neil.banerjee@uwo.ca
AF: Department of Earth Sciences, University of Western Ontario, London, Ont N6A 5B7, Canada
AB: Fe and Mn oxidizing microbes interact with their environment through the microbially mediated formation of Fe/Mn oxides and through the corrosion textures they may leave behind in the solids they colonize and from which they extract nutrients. Understanding the geo-biology of Fe and Mn oxidation may focus on the study of the microbes themselves, the mineral products, its biocorrosion features and the relationships between these types of observations. We have reviewed our own data on glass bio-corrosion and in particular the wider literature on microbial mineral tunneling to develop a two stage biocorrosion model for volcanic glass that offers feedback for our understanding of the mechanisms and the dynamics of microbial dissolution. Traces of microbially mediated dissolution of volcanic glass are commonly observed in volcanic glass found in submarine volcanoes on the seafloor, and in uplifted submarine volcanoes of almost any geological age back to the origin of life. Two main bioalteration textures care observed, granular and tubular. Based on a comparison of these features in particular with tunneling by ectomycorrhizal fungi, we propose two distinct types of biocorrosion that affects glass: (1) Granular alteration textures, made up of colonies of microbe-sized, near spherical mineral - filled cavities that form irregular clusters ranging to a tens of micron thick bands at the glas surfaces. These granular textures are interpreted as the result of microbial colonization. accompanied by dissolution of the glass in their contact surface, deposition of authigenic minerals and the formation of a biofilm, that eventually seals the glass from easy access by seawater for hydration, or from microbes accessing Fe (II) in the glass. (2) The most spectacular bioalteration feature, repesented by the formation of tubes cannot be easily formed by the former mechanism because near spherical, individual microbes are likely not to produce the directionality that is required to produce the near linear or sometimes coiled tubes. Instead, we envision the activity of hyphae-like organelles or filaments, that may radiate out from a host body located in direct contact with circulating water, possibly penetrating a biofilm and entering/drilling into the fresh glass. Such microdrilling is well described in soils, where hyphae can slowly drill into silicates, in a process that takes about 1000 years to become visible as tunnels.
DE: 0400 BIOGEOSCIENCES
DE: 0419 Biomineralization
DE: 0448 Geomicrobiology
DE: 0460 Marine systems (4800)
DE: 0463 Microbe/mineral interactions
SC: Biogeosciences [B]
MN: 2007 Fall Meeting