B. Amard et J. Bertrandsarfati, MICROFOSSILS IN 2000 MA OLD CHERTY STROMATOLITES OF THE FRANCEVILLE GROUP, GABON, Precambrian research, 81(3-4), 1997, pp. 197-221
A well-preserved microbial assemblage has been found in Paleoproterozo
ic cherty stromatolites from the 2000 Ma old Franceville Group, Gabon.
This assemblage contains coccoids and star-like forms, filaments and
budding tubular forms. These various forms are mostly of cyanobacteria
l affinity, and among them nostocalean akinetes (Archaeoel-lipsoides)
are reported, for the first time, from rocks older than the Mesoproter
ozoic. The most noteworthy discovery in the Franceville biota is the G
unflint-type association Huroniospora-Gunflintia- Archaeorestis, known
also - without Archaeorestis - in other Paleoproterozoic assemblages
throughout the world. The present assemblage comprises 13 taxa consist
ing of 8 species belonging to 10 genera and 2 unnamed forms. It is dom
inated by Gunflintia filaments, regarded as a mat-building community a
nd by Huroniospora coccoids, probably mat-dwellers and/or plankters. T
he rare and large forms such as akinetes of Archaeoellipsoides were al
lochthonous and presumably planktonic.