 |
|
|
|
Selected Publications |
Earth's Earliest Microbial Mats in a Siliciclastic Marine Environment (Mozaan Group, 2.9 Ga, South Africa)
|
|
Abstract: This study provides evidence for the existence of filamentous
(cyano-) bacteria forming sediment-stabilizing mats in shelf environments
at 2.9 Ga-the oldest known occurrence of microbial
mats in siliciclastic rocks. The Mesoarchean Mozaan Group, South
Africa, features fine-grained quartzites of an ancient shallow-shelf
environment. These sandstones contain wrinkle structures, which
in thin section reveal filamentous textures forming carpet-like microbial
mat fabrics. The textures resemble the trichomes of modern
cyanobacteria, chloroflexi, or sulfur-oxidizing proteobacteria. Mineralogical,
geochemical, and isotopic analyses are consistent with a
biological origin of the filament-like textures. Carbon filaments
with biogenic isotopic signatures (d13C 5 224.2‰ 6 0.5‰) are
closely associated with hematite, goethite, and chert minerals,
which may derive from the former presence of oxygen within the
microbial mats. Detrital quartz, zircon, and rutile in the mats could
indicate baffling, trapping, and binding of the bacterial
communities.
Keywords: Noffke, microbially induced sedimentary structures, cyanobacteria,
Pongola Supergroup, Archean, siliciclastic rocks.
PDF |
|
|
|
|
|
|
 |
|
|
