Endolithic microbes in seafloor basalt and their influence on the chemical alteration
Abstract
Samples of recent lava flows from the Arctic Ridges have been studied by electron microscopy and geochemical analyses, aimed at describing the endolithic microbial community and its influence on the chemical alteration of the glassy margins. The samples were collected at 2000-3500 m below sea level and the ambient seawater temperature was measured to -0.7^oC. SEM observations reveal that coccoids, rods and star-shaped microbial cells are associated with the alteration rims, developed along intersecting fractures and cracks in the glass. The microbes are frequently encrusted and partially fossilised, due to precipitation of alteration products around the cells. Alteration rims showing numerous microbial morphologies nearly throughout, suggest a high content of living and/or fossilized cells. This is supported by an organic carbon content of about 0.25 wt.%, which indicates 1010 cells per 1 g altered glass, assuming 10-13g of C per cell. The altered glass is highly enriched in Fe, Ti, P and K, and depleted in Si and Ca, while Al may be enriched or depleted, compared to the fresh, unaltered glass. TEM/EDS analyses show that the cell encrustations are commonly enriched in Mn and P compared to the surrounding altered glass. This may indicate Mn-utilization in an energy metabolic process.
- Publication:
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EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA....13765K