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| Fammenian | |
|---|---|
| Name | Fammenian |
| Color | #FFD58A |
| Time start | 372.2 |
| Time end | 358.9 |
| Time end uncertainty | 0.4 |
| Caption | Stratotype sections and facies typical of the late Devonian interval |
| Lower boundary def | Global Boundary Stratotype Section and Point (GSSP) |
| Lower boundary def location | Kowala, Poland |
| Lower boundary def acceptance | 1985 |
| Upper boundary def | Global Boundary Stratotype Section and Point (GSSP) |
| Upper boundary def location | La Serre, France |
| Upper boundary def acceptance | 1992 |
Fammenian The Fammenian is the latest age and stage of the Devonian Period, spanning the final interval of the Late Devonian Epoch and preceding the Carboniferous. It records critical biotic crises and environmental shifts documented across classic sections such as Kowala, La Serre, and the Frasnian–Fammenian boundary GSSP proposals. The interval is central to studies of the Late Devonian extinction, reef collapse in the Canning Basin, and floral turnovers linked to events recorded in the Rhenish Massif and Appalachian Basin.
The name derives from the Famennian variant tied to the La Famenne region in the Ardennes and Hainaut provinces, originally proposed by 19th‑century geologists working in the Belgian Ardennes and the Paris Basin. Formalization of the stage involved committees of the International Commission on Stratigraphy and stratigraphers associated with institutions such as the Geological Society of London and the United States Geological Survey. Nomenclatural decisions referenced stratotypes in the Rhenish Massif, the Holy Cross Mountains, and comparative faunal lists from the Buchan region and the Anti-Atlas.
The Fammenian follows the Frasnian and ends at the Devonian–Carboniferous boundary defined by GSSPs correlated with sections in La Serre and La Malène. Its chronostratigraphic placement is constrained by radiometric ages from zircons in tuffs linked to sequences in the Armorican Massif, Newfoundland Appalachians, and Mackenzie Mountains. Biostratigraphic frameworks employ conodont zonations tied to taxa described by researchers at the Natural History Museum, London, the Smithsonian Institution, and universities such as Uppsala University and University of Kansas.
Fammenian deposits record shallow marine platforms, reefal buildups, anoxic basins, and siliciclastic deltas across basins like the Rheic Ocean margins, the Kaskaskia Sea, and the Old Red Sandstone facies. Sedimentological analyses from the Catskill Formation, Woodford Shale, and Givetian–Frasnian transitions document storm beds, turbidites, and black shale horizons comparable to those in the Rhynie Chert studies and in the Cantabrian Zone. Evidence from isotopic work carried out at institutions including ETH Zurich and Lamont–Doherty Earth Observatory highlights excursions in carbon and oxygen isotopes associated with basinwide anoxia and euxinia recorded in sections such as Canning Basin cores and Central European Basin outcrops.
The Fammenian is characterized by turnover among conodont genera, radiations and extinctions of placoderm fishes, the decline of stromatoporoid and rugose coral reefs, and diversification in early tetrapod and sarcopterygian lineages documented from localities like East Greenland, Ludford Lane, and Gogo Formation. Key taxa used in zonation include conodont species described by Evgeny Kozur, Axel Walliser, and A.V. Nikitin. Vertebrate assemblages involve genera studied by researchers at the Natural History Museum, London and American Museum of Natural History, while plant assemblages comparable to those in the Rhynie Chert and Scotland record progymnosperm and lycopsid elements. Faunal crises correlated with the Kellwasser Event and the Hangenberg Event are recorded via extinction patterns in trilobites, brachiopods, and ammonoids examined in collections at the Muséum national d'Histoire naturelle and the Senckenberg Gesellschaft für Naturforschung.
Fammenian strata are recognized across Europe, North America, South America, Africa, Asia, and Australia in basins and terranes such as the Armorican Massif, Appalachian Basin, Amazon Basin, Anti-Atlas, South China Block, Timor, Mackenzie Mountains, Canning Basin, and the Beijing Block. Correlations utilize biozones established by conodont workers in collaboration with regional geological surveys like the British Geological Survey, Geological Survey of Canada, Servicio Geológico Colombiano, and the Geological Survey of India. Interbasinal links are further refined by radiometric tie‑points from laboratories at Caltech, University of Tokyo, and GEOMAR.
Fammenian black shales and organic‑rich facies are source rocks for hydrocarbons with plays documented in the North Sea, Permian Basin analogues, and the Western Canada Sedimentary Basin, evaluated by companies such as Schlumberger and BP. Phosphorite and ironstone horizons in Fammenian‑equivalent sequences have been targeted in the Brazilian Amazon and Morocco; mineralizations have been mapped by national agencies including Bureau of Economic Geology and Geological Survey of Brazil. Limestone and dolostone from reefal remnants are quarried for construction in the Belgian Ardennes and the Massif Central, and sequences with uranium‑bearing shales were investigated by researchers at Oak Ridge National Laboratory and Czech Geological Survey.
Early descriptions of the stage date to 19th‑century geologists working in Belgium, France, and Germany such as contributors to the Society of Geology of France and correspondents of the Royal Society. Systematic biozonation and GSSP proposals were advanced by committees of the International Union of Geological Sciences and stratigraphers publishing in journals affiliated with Cambridge University Press and Elsevier. Landmark monographs and regional syntheses were produced by researchers at institutions including University of Cambridge, Utrecht University, Vrije Universiteit Brussel, and the Polish Geological Institute, leading to the current formal scheme adopted by the International Commission on Stratigraphy.