Episodes

Vol. 28 No.1 March 2005

Journal of International Geoscience

Published by the International Union of Geological sciences

by Frederik Hilgen1, Hayfaa Abdul Aziz1,2, David Bice3, Silvia Iaccarino4,Wout Krijgsman2, Klaudia Kuiper1,5, Alessandro Montanari6, Isabella Raffi7,Elena Turco4, and Willem-Jan Zachariasse1

The Global boundary Stratotype Section and Point (GSSP) of the Tortonian Stage (Upper Miocene) at Monte Dei Corvi

1 Stratigraphy/Paleontology, Dept. of Earth Sciences, Utrecht University, The Netherlands (Email:fhilgen@geo.uu.nl)
2 Paleomagnetic Lab. ¡°Fort Hoofddijk¡±, Dept. of Earth Sciences, Utrecht University, The Netherlands
3 Department of Geology, Carleton College, Northfield MN 55057, USA
4 Dipartimento di Scienze della Terra, Universita degli Studi di Parma, Parma, Italy
5 Department of Isotope Geochemistry, Vrije Universiteit Amsterdam, The Netherlands
6 Osservatorio Geologico di Coldigioco, 62020 Frontale di Apiro, Italia
7 Dip. di Scienze della Terra, Univ. ¡°G. D¡¯Annunzio¡±, 66013 Chieti Scalo, Italy

Abstract

The GSSP of the Tortonian Stage, which per definition marks the base of the Tortonian and, hence, the boundary between the Serravallian and Tortonian Stages of the Middle and Upper Miocene Subseries, has recently been defined and ratified by the IUGS. The boundary stratotype-section is Monte dei Corvi (Italy) where the Tortonian GSSP is now formally at the mid-point of the sapropel of small-scale sedimentary cycle no. 76, close to the last common occurrences (LCOs) of the calcareous nannofossil Discoaster kugleri and the planktonic foraminifer Globigerinoides subquadratus and associated with the short normal subchron C5r.2n. The GSSP level coincides closely with oxygen isotope event Mi-5 and the associated glacio-eustatic sea-level low-stand of supercycle T3.1 and concurrent deep-sea hiatus NH4, and is dated astronomically at 11.608 Ma. The Monte Gibliscemi section is accepted as an auxiliary boundary stratotype because the better preservation of the calcareous microfossils in this section enables quantitative analyses and the construction of a stable isotope record.

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