Moyabi, Franceville-Moanda road: Orosirian, Gabon

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
unclassified
Myxococcoides minuta (Muir 1976)
Coccogoneae - Chroococcales - Chroococcaceae
Sphaerophycus parvum Schopf 1968
Tetraphycus major Oehler 1978
Eosynechococcus medius Hofmann 1976
Hormogoneae - Nostocales - Nostocaceae
Archaeoellipsoides elongatus (Golovenok and Belova 1984)
Archaeoellipsoides dolichos (Zhang 1985)
unclassified
Eoastrion simplex Barghoorn 1965
Archaeorestis sp. Barghoorn 1965
? Germinosphaera sp. Mikhailova 1986
Huroniospora sp. Barghoorn 1965
Gunflintia minuta Barghoorn 1965
see common names

Geography
Country:Gabon
Coordinates: 1.6° South, 13.3° East (view map)
Paleocoordinates:0.0° North, 0.0° East
Basis of coordinate:based on nearby landmark
Geographic resolution:local area
Time
Period: Orosirian
Key time interval: Orosirian
Age range of interval: 2050 - 1800 m.y. ago
Age estimate: 2027 ± 55 to 2003 ± 16 Ma (U/Pb)
Stratigraphy
Stratigraphic resolution:group of beds
Stratigraphy comments: Stromatolites occur at the base of the transgressive Francevillian FC Formation. A welded tuff in the lower part of the overlying FD Formation (East of Lastoursville) and gave 2083 ± 6 Ma U/Pb zircon age (SHRIMP) (Horie et al., 2005, Gauthier-Lafaye, 2006) and 2072 ± 29 Ma (LA-ICPMS-MC, Bouton et al., 2009a, Thiéblemont et al., 2009) from a volcano-siliciclastic rock. According to Weber et al. (2016), a reappraisal of the U–Pb data set shows that the age of 2083 ± 6 Ma corresponds to a mixing of two populations of zircon with ages, of 2136–2068 Ma and 2042–2003 Ma, respectively. The youngest age of 2003 ± 16 Ma obtained on a subconcordant zircon could represent the time of emplacement of these pyroclastic flows. The N'Goutou complex from the underlying Francevillian B in the neighboring Okondja basin yields a U-Pb age on zircon of 2027 ± 55 Ma (Moussavou and Edou Minko, 2006).
Lithology and environment
Primary lithology:stromatolitic lithified cherty/siliceous dolomite
Environment:peritidal
Taphonomy
Modes of preservation:body,permineralized,original carbon,replaced with silica
Size of fossils:macrofossils
Collection methods and comments
Collection methods:peel or thin section
Reason for describing collection:taxonomic analysis
Metadata
Database number:227624
Authorizer:M. Clapham Enterer:M. Clapham
Modifier:M. Clapham
Created:2022-10-23 20:48:43 Last modified:2022-10-23 20:48:51
Access level:the public Released:2022-10-23 20:48:43
Creative Commons license:CC BY
Reference information

Primary reference:
82914. B. Amard and J. Bertrand-Sarfati. 1997. Microfossils in 2000 Ma old cherty stromatolites of the Franceville Group, Gabon. Precambrian Research 81:197-221 [M. Clapham/M. Clapham]