Thanetian

Thanetian
Name	Thanetian
Start	59.2
End	56.0
Unit	Age
Era	Paleogene
Period	Paleogene
Namedafter	Thanet
Timescalesource	ICS

Thanetian The Thanetian is the uppermost age of the Paleocene Epoch in the Paleogene Period, marking a critical interval immediately before the Eocene Epoch and the Paleocene–Eocene Thermal Maximum. It is defined by marine biostratigraphy and chemostratigraphy observed in type sections in the United Kingdom and correlated globally through isotope excursions, magnetostratigraphy, and global stage boundaries established by the International Commission on Stratigraphy. The interval co-occurs with regional regional stages such as the Clarkforkian and Tiffanian in North America and has been central to debates involving North Sea stratigraphy, Paris Basin successions, and Tethyan correlations.

Definition and Nomenclature

The age name derives from the Isle of Thanet off the Kent coast in the United Kingdom, where classic exposures in Pegwell Bay and the Thanet Formation provided early type sections for Paleocene stratigraphy. Formal ratification by the International Commission on Stratigraphy established the base and top boundaries by events tied to calcareous nannoplankton and planktonic foraminifera bioevents recognized in sections such as the GSSP proposals in the Dorset and Somerset basins. Historical usage appears in works by Adam Sedgwick and later by Charles Lyell-era stratigraphers, and has been refined through studies at institutions like the British Geological Survey, the Natural History Museum, London, and the University of Cambridge.

Stratigraphy and Chronology

Bounded below by the Selandian and above by the Ypresian, the age duration is constrained by magnetostratigraphic chrons correlated to the Geomagnetic Polarity Time Scale and by stable isotope excursions recognized in cores from the Walvis Ridge, Deep Sea Drilling Project sites, and Ocean Drilling Program legs. Key biostratigraphic markers include the last occurrence of certain nannoplankton species and first occurrences of planktonic foraminifera taxa used by research groups at the Smithsonian Institution, Natural Environment Research Council, and universities such as Oxford and Cambridge. Chronometrically, radiometric ties from volcanic ash layers in basins such as the Montana Basin and Iberian Basin via laboratories like USGS and CNRS have refined the age to roughly 59.2–56.0 Ma.

Paleogeography and Climate

Paleogeographic reconstructions by teams at Paleomap Project, University of Chicago, and Columbia University depict continents arranged with a narrowing Tethys Ocean, active rifting along the North Atlantic Igneous Province, and marine gateways influencing circulation between the Arctic Ocean and Atlantic Ocean. Climate proxies, including oxygen isotope records from Deep Sea Drilling Project cores, indicate a generally warm greenhouse climate with poleward heat transport documented in studies at Scripps Institution of Oceanography, Woods Hole Oceanographic Institution, and Lamont–Doherty Earth Observatory. The interval precedes the abrupt warming event recognized in deposits tied to researchers from Caltech, ETH Zurich, and the University of Bergen, and shows elevated atmospheric CO2 inferred from stomatal indices analyzed at University of Exeter and University College London.

Biota and Paleontology

Marine faunas include diverse planktonic foraminifera and calcareous nannoplankton with important assemblages described by paleontologists at Natural History Museum, Paris, University of Copenhagen, and Yale University. Terrestrial records show mammalian radiations documented in the Willwood Formation, Bighorn Basin, and Paskapoo Formation, with notable taxa discussed in monographs from American Museum of Natural History, Field Museum, and New York Botanical Garden. Plant macrofossils and palynological spectra from the Rhineland Basin, Northern Spain, and Green River Basin indicate diverse angiosperm communities analyzed by researchers at Smithsonian Institution, University of Michigan, and University of California, Berkeley. Important vertebrate groups include early perissodactyls and primates whose systematics have been advanced by teams at Harvard University, University of Pennsylvania, and the Carnegie Museum of Natural History. Invertebrate assemblages in the Paris Basin and North Sea records were revised by scientists at Royal Holloway, University of Leicester, and Leiden University.

Events and Extinctions

The interval includes faunal turnovers and regional extinctions tied to climatic perturbations, volcanism in the North Atlantic Igneous Province, and changes in ocean chemistry recorded in sections studied by Lamont–Doherty Earth Observatory and GEOMAR Helmholtz Centre. The age precedes the pronounced hyperthermal event identified by correlations to the Paleocene–Eocene Thermal Maximum, and researchers from ETH Zurich, University of Bristol, and Utrecht University have documented isotope excursions and biotic responses in carbonate platforms and terrestrial strata. Sea-level changes reflected in the Chalk Group and Wessex Basin successions influenced reefal and shelf ecosystems examined by teams at the British Antarctic Survey, National Museum of Natural History, Paris, and University of Bonn.

Regional Correlations and Lithostratigraphy

Regional equivalents include the Tiffanian and Clarkforkian of North America, the Danian-adjacent sequences in the Paris Basin, and marine successions in the Tethys realm with lithostratigraphic units such as the Thanet Formation, Ieper Group, Chattanooga Shale-adjacent deposits, and Pebidian-age correlations refined by stratigraphers at the British Geological Survey, Royal Belgian Institute of Natural Sciences, and Institut Français du Pétrole. Hydrocarbon-bearing intervals in the North Sea and Gulf of Mexico have been correlated to Thanetian strata by industry groups including BP, Shell, and ExxonMobil with geoscience contributions from Schlumberger and Halliburton. Continental successions in India, China, Argentina, and Morocco provide additional lithostratigraphic comparisons utilized in global synthesis efforts led by International Union of Geological Sciences and regional surveys by Geological Survey of India and Servicio Geológico Minero Argentino.

Category:Paleogene