Where: Gabon (1.6° S, 13.3° E: paleocoordinates 0.0° N, 0.0° E)

• coordinate based on nearby landmark

• local area-level geographic resolution

When: Orosirian (2050.0 - 1800.0 Ma)

• 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).

• group of beds-level stratigraphic resolution

Environment/lithology: peritidal; lithified, stromatolitic, cherty/siliceous dolomite

Size class: macrofossils

Preservation: permineralized, original carbon, replaced with silica

Collection methods: peel or thin section

Primary reference: 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]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 227624: authorized by Matthew Clapham, entered by Matthew Clapham on 23.10.2022

Creative Commons license: CC BY (attribution)