Francevillian B Formation
| Francevillian B Formation | |
|---|---|
| Stratigraphic range: Palaeoproterozoic (Rhyacian) | |
| Type | Geological formation |
| Unit of | Francevillian Basin |
| Area | 25,000 square kilometers (9,700 sq mi) |
| Lithology | |
| Primary | Black Shale |
| Location | |
| Region | East-central Gabon |
| Country | Gabon |
| Extent | 35,000 kilometers (22,000 mi) |
| Type section | |
| Named for | Franceville, a nearby town |
| Named by | Abderrazak El Albani |
Map of the Geology of the Franceville basin | |
| Part of a series on |
| The Francevillian basin |
|---|
The Francevillian B Formation, also known as the Francevillian Formation or FB2 in scientific research, is a geologic formation of black shale provinces close to the town of Franceville, Gabon from which it gets its name. The formation was deposited between 2.14-2.08 Ga (billion years ago) in the Palaeoproterozoic, and, uniquely, has not experienced any thermal overprinting due to diagenesis after burial nor significant metamorphism since it was deposited, unlike other formations deposited around the same time. The formation contains possible fossils, including the macroscopic "Francevillian Biota", which has been suggested by some authors to represent the oldest known multicellular organisms, though other authors have questioned the supposed biological origin of the structures, and have suggested that they may instead be inorganic, such as artifacts of diagenesis.