Triassic stromatolitic dolomite from Italy preserves mineralized bacterial remains, one of the fi rst unequivocal identifi cations of such structures in the geological record. They consist of empty spheroids ~1.0 μm diameter resembling coccoid bacteria, and smaller, 150–400 nm, objects interpreted as dwarf bacterial forms, occurring within and between syn-sedimentary dolomite crystals. Moreover, gently folded sheets, 100–200 nm thick and several micrometers long, form a sub-polygonal network reminiscent of EPS (extracellular polymeric substance). Their granular-textured surfaces suggest bacterial degradation of original organic matter. These features confi rm a biological origin for the stromatolites, as in modern microbial mats, and the preserved original geochemical signatures indicate early precipitation of Mg-carbonates induced through microbial sulfate-reducing metabolic activities.

Bacterial Fossils and Microbial Dolomite in Triassic Stromatolites

PERRI, Edoardo;
2007-01-01

Abstract

Triassic stromatolitic dolomite from Italy preserves mineralized bacterial remains, one of the fi rst unequivocal identifi cations of such structures in the geological record. They consist of empty spheroids ~1.0 μm diameter resembling coccoid bacteria, and smaller, 150–400 nm, objects interpreted as dwarf bacterial forms, occurring within and between syn-sedimentary dolomite crystals. Moreover, gently folded sheets, 100–200 nm thick and several micrometers long, form a sub-polygonal network reminiscent of EPS (extracellular polymeric substance). Their granular-textured surfaces suggest bacterial degradation of original organic matter. These features confi rm a biological origin for the stromatolites, as in modern microbial mats, and the preserved original geochemical signatures indicate early precipitation of Mg-carbonates induced through microbial sulfate-reducing metabolic activities.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11770/130173
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