Burdigalian

Burdigalian
Name	Burdigalian
Time start	20.44
Time end	15.97
Unit	Stage
Preceded by	Aquitanian
Followed by	Langhian

Burdigalian The Burdigalian is an early Neogene chronostratigraphic stage of the Miocene Epoch defined by marine biostratigraphy and lithostratigraphic correlations. It is recognized worldwide through ammonite, foraminifera, and nannofossil assemblages tied to type sections and global stage boundaries established by stratigraphers and institutions such as the International Commission on Stratigraphy, Geological Society of London, United States Geological Survey, Natural History Museum, London, and major university geology departments. Key regions with Burdigalian successions include portions of the Paratethys, Mediterranean Sea, Caribbean Sea, Pacific Ocean, and continental basins studied by teams from University of Cambridge, University of California, Los Angeles, University of Vienna, and Sapienza University of Rome.

Definition and stratigraphic context

The stage was originally defined using marine sections in southwestern France and northwestern Italy studied by 19th‑century stratigraphers including Charles Lyell, later formalized by stratigraphic work from institutions like the Paris Museum of Natural History and Italian Geological Survey. The Burdigalian boundary definitions rely on first and last occurrences of planktonic foraminifera and calcareous nannoplankton correlated to magnetostratigraphic chronozones developed by researchers at Scripps Institution of Oceanography, Lamont–Doherty Earth Observatory, and the Max Planck Institute for Chemistry. Stage correlations use regional chronostratigraphic frameworks such as the European Neogene stratigraphy, the North American Land Mammal Ages, and the South American Land Mammal Ages as applied in syntheses by teams from Smithsonian Institution and Natural History Museum of Los Angeles County.

Chronology and geologic time scale placement

The Burdigalian spans roughly from 20.44 to 15.97 million years ago in the global time scale maintained by the International Commission on Stratigraphy and adopted by agencies such as the International Union of Geological Sciences. Its base is placed above a magnetic reversal tied to chron C6An and biostratigraphic markers used by researchers at European Geosciences Union meetings and in publications from Geological Society of America. The top of the Burdigalian coincides with the base of the Langhian and is often correlated with land mammal events documented in work by paleontologists at American Museum of Natural History and Museo Argentino de Ciencias Naturales.

Paleogeography and depositional environments

During the Burdigalian, continental configurations reflected the post‑Oligocene plate reorganizations recorded by marine geologists at Woods Hole Oceanographic Institution and tectonic syntheses from Geological Survey of India and Geological Survey of Japan. Sea levels and gateway dynamics influenced depositional settings in the Mediterranean Sea, Paratethys, Caribbean Sea, and western Pacific Ocean basins investigated by teams from Universidad Nacional Autónoma de México, University of Auckland, and University of Tokyo. Depositional environments ranged from shallow marine carbonate platforms in sections studied near Spain and Italy to siliciclastic deltas in basins researched by geologists at University of Texas at Austin and Columbia University. Rift basins and foreland settings documented in the Alpine orogeny and Himalayan orogeny produced terrestrial sequences correlated with marine Burdigalian strata by researchers from ETH Zurich and Indian Institute of Science.

Climate and paleoenvironmental changes

Burdigalian climates show trends toward warming and increased thermohaline circulation discussed in syntheses by National Oceanic and Atmospheric Administration scientists and paleoclimatologists at Potsdam Institute for Climate Impact Research. Isotopic records from benthic foraminifera in cores analyzed at British Antarctic Survey and GEOMAR Helmholtz Centre for Ocean Research indicate shifts in deep water temperatures and carbon cycling tied to global events recognized in International Ocean Discovery Program results. Vegetation responses in continental pollen records assembled by researchers at University of Göttingen and University of São Paulo document expansions of subtropical flora in regions including North Africa, Central America, and Southeast Asia, with implications explored by teams at Royal Botanic Gardens, Kew and Chinese Academy of Sciences.

Paleontology and biotic events

The Burdigalian interval preserves diverse marine faunas—mollusks, echinoderms, and foraminifera—cataloged in museum collections at Natural History Museum, London and Muséum national d'Histoire naturelle, Paris. Significant vertebrate records include early Miocene cetaceans from localities studied by paleontologists at University of California, Berkeley and Florida Museum of Natural History, and terrestrial mammal assemblages documented by researchers at American Museum of Natural History, Museo de La Plata, and Museo Nacional de Ciencias Naturales (Spain). Radiations and dispersal events for groups such as proboscideans, perissodactyls, and rodents are correlated with Burdigalian strata in regional syntheses by teams at Smithsonian Tropical Research Institute and University of Buenos Aires. Marine microplankton turnover events identified by scientists at National Oceanography Centre and University of Bremen serve as biostratigraphic markers for correlating global successions.

Regional stratigraphy and type sections

Classic type sections and reference localities include marine sequences in southwestern France studied historically at institutions like Muséum d'histoire naturelle de Bordeaux, and Italian exposures in the Tuscany and Friuli regions investigated by researchers from University of Florence and University of Trieste. Other important Burdigalian sequences occur in the Vienna Basin documented by the Geological Survey of Austria and in the Gippsland Basin examined by geoscientists from Geoscience Australia. Deep‑sea cores tied to the Integrated Ocean Drilling Program and IODP expeditions provide global correlation through planktonic assemblages analyzed at Woods Hole Oceanographic Institution and University of Bremen, while continental successions in South America and Africa are referenced in studies from Museo Argentino de Ciencias Naturales and Geological Survey of Namibia.

Category:Miocene stages