Episodes 2011; 34(4): 220-243
Published online December 1, 2011
Copyright © International Union of Geological Sciences.
Birger Schmitz1, Victoriano Pujalte2, Eustoquio Molina3, Simonetta Monechi4, Xabier Orue-Etxebarria2, Robert P. Speijer5, Laia Alegret3, Estibaliz Apellaniz2, Ignacio Arenillas3, Marie-Pierre Aubry6, Juan-Ignacio Baceta2, William A. Berggren7, Gilen Bernaola8, Fernando Caballero2, Anne Clemmensen9, Jaume Dinarès-Turell10, Christian Dupuis11, Claus Heilmann-Clausen9, Asier Hilario Orús12, Robert Knox13, Maite Martín-Rubio8, Silvia Ortiz3, Aitor Payros2, Maria Rose Petrizzo14, Katharina von Salis15, Jorinde Sprong5, Etienne Steurbaut16 and Erik Thomsen9
1Department of Geology, Lund University, SE-22362 Lund, Sweden. Email: birger.schmitz@ geol.lu.se
2Department of Stratigraphy and Paleontology, University of the Basque Country, E-48080 Bilbao, Spain.
3Department of Earth Sciences, Zaragoza University, E-50009 Zaragoza, Spain.
4Department of Earth Sciences, Florence University, I-50121 Florence, Italy.
5Department of Earth and Environmental Sciences, K.U. Leuven, B-3001 Leuven, Belgium.
6Department of Geology, Rutgers University, Piscataway, NJ 08854, USA.
7Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA.
8Department of Mining and Metallurgic Engineering and Material Sciences, University of the Basque Country, E-48901 Barakaldo, Spain.
9Department of Earth Sciences, Århus University, DK-8000 Århus C, Denmark.
10Instituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, I-00142 Rome, Italy.
11Laboratoire de Géologie Fondamentale et Appliquée, Faculté Polytechnique de Mons, B-7000 Mons, Belgium.
12Eguzkialde 13, E-20271 Irura, Gipuzkoa, Spain.
13British Geological Survey, Kingsley Durham Centre, Keyworth, Nottingham NG12 5GG, United Kingdom.
14Department of Earth Sciences, Milano University, I-20133 Milano, Italy.
15Via Maistra 9, CH-7513 Silvaplana, Switzerland.
16Department of Paleontology, Royal Belgian Institute of Natural Sciences, B-1000 Brussels, Belgium.
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The global stratotype sections and points for the bases of the Selandian (Middle Paleocene) and Thanetian (Upper Paleocene) stages have been defined in the coastal cliff along the Itzurun Beach at the town of Zumaia in the Basque Country, northern Spain. In the hemipelagic section exposed at Zumaia the base of the Selandian Stage has been placed at the base of the Itzurun Formation, ca. 49 m above the Cretaceous/Paleogene boundary. At the base of the Selandian, marls replace the succession of Danian red limestone and limestone-marl couplets. The best marine, global correlation criterion for the basal Selandian is the second radiation of the important calcareous nannofossil group, the fasciculiths. Species such as Fasciculithus ulii, F. billii, F. janii, F. involutus, F. pileatus and F. tympaniformis have their first appearance in the interval from a few decimetres below up to 1.1 m above the base of the Selandian. The marker species for nannofossil Zone NP5, F. tympaniformis, first occurs 1.1 m above the base. Excellent cyclostratigraphy and magnetostratigraphy in the section creates further correlation potential, with the base of the Selandian occuring 30 precession cycles (630 kyr) above the top of magnetochron C27n. Profound changes in sedimentology related to a major sea-level fall characterize the Danian-Selandian transition in sections along the margins of the North Atlantic.
The base of the Thanetian Stage is placed in the same section ca. 78 m above the Cretaceous/Paleogene boundary. It is defined at a level 2.8 m 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 in the section. The base of the Thanetian is not associated with any significant change in marine micro-fauna or flora. The calcareous nannofossil Zone NP6, marked by the first occurrence of Heliolithus kleinpelli starts ca. 6.5 m below the base of the Thanetian. The definitions of the global stratotype points for the bases of the Selandian and Thanetian stages are in good agreements with the definitions in the historical stratotype sections in Denmark and England, respectively.