The base of the Thanetian Stage is defined in the sea-cliff along the main beach of the coastal town Zumaia, Basque Country, northern Spain. The GSSP is about 78m above the Cretaceous/Paleogene boundary. The GSSP is defined at a level 2.8m or eight precession cycles above the base of the core of the distinct clay-rich interval associated with the Mid-Paleocene Biotic Event, and it corresponds to the base of magnetochron C26n.
The GSSP of the Thanetian Stage is located along the main beach, of the coastal town Zumaia, Basque Country, northern Spain at a latitude of 43º 17' 58.4"N, and a longitude of 02º 15' 39.1"W. The GSSP for the Thanetian is about 78 m above the Cretaceous/ Paleogene boundary.
The lower part of the Itzurun Formation can be subdivided into a lower, ca. 24m thick Member A and an upper, 52m thick Member B. The boundary between the two members is 6.5m below the GSSP. The turbidite intercalations of the marly Member A are mostly siliciclastic, whereas in Member B, they are siliciclastic or mixed carbonatic-siliciclastic. About 3 m above the limit between Member A and B of the Itzurun Formation is a prominent dark, ca. 1m thick interval recording a drastic decrease in CaCO3. This clay is interpreted as the Mid-Paleocene Biotic Event
The Thanetian GSSP corresponds to the base of magnetochron C26n.
Magnetic -- Base of Chron C26n
Astronomical cycles in sediments scaled from base Paleocene, using base of magnetic polarity chronozone C26n. Arbitrary 0.1 (2 precession cycles, plus the base-Paleogene radiometric) uncertainty assigned to all estimates.
Schmitz, B., Pujalte, V., Molina, E., Monechi, S., Orue-Etxebarria, X., Speijer, R.P., Alegret, L., Apellaniz, E., Arenillas, I., Aubry, M-P., Baceta, J.I., Berggren, W.A., Bernaola, G., Caballero, F., Clemmensen, A., Dinarès-Turell, J., Dupuis, C., Heilmann-Clausen, C., Hilario Orús, A., Knox, R., Martín-Rubio, M., Ortiz, S., Payros, A., Petrizzo M.R., von Salis, K., Sprong, J., Steurbaut, E., & Thomsen, E., 2011. The Global Stratotype Sections and Points for the bases of the Selandian (Middle Paleocene) and Thanetian (Upper Paleocene) stages at Zumaia Spain. Episodes 34/4, p. 220-243.