High-precision U-Pb zircon age from the Triassic of Italy: Implications for the Triassic time scale and the Carnian origin of calcareous nannoplankton and dinosaurs
- Stefano Furin*1,
- Nereo Preto2,
- Manuel Rigo2,
- Guido Roghi3,
- Piero Gianolla4,
- James L. Crowley5 and
- Samuel A. Bowring5
- 1Dipartimento di Scienze della Terra, Università degli Studi di Ferrara, Via G. Saragat 1, 44100 Ferrara, Italy
- 2Dipartimento di Geologia, Paleontologia e Geofisica, Università degli Studi di Padova, Via Giotto 1, 35137 Padova, Italy
- 3Institute of Geosciences and Georesources, C.N.R., Corso Garibaldi 37, 35137 Padova, Italy
- 4Dipartimento di Scienze della Terra, Università degli Studi di Ferrara, Via G. Saragat 1, 44100 Ferrara, Italy
- 5Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
Abstract
The Triassic time scale is poorly constrained due to a paucity of high-precision radiometric ages. We present a 206Pb/238U age of 230.91 ± 0.33 Ma (error includes all known sources) for zircon from an ash bed in the upper Carnian (Upper Triassic) of southern Italy that requires a major revision of the Triassic time scale. For example, the Norian stage is lengthened to more than 20 m.y. The section containing the ash bed is correlated with other Tethyan sections and, indirectly, with the Newark astronomical polarity time scale (APTS). The dating provides also a minimum age for some important climatic and biotic events that occurred during the Carnian. We note a coincidence between these events and the eruption of the large igneous province of Wrangellia, but the possible link between volcanism and climatic and biotic events requires further scrutiny.
- geochronology
- geologic time scale
- Late Triassic
- dinosaurs
- calcareous nannoplankton
- large igneous provinces
Footnotes
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↵*stefano.furin{at}unife.it
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↵GSA Data Repository item 2006222, analytical methods used in U-Pb geochronology and U-Pb isotopic data table, is available online at www.geosociety.org/pubs/ft2006.htm, or on request from editing{at}geosociety.org or Documents Secretary, GSA, P.O. Box 9140, Boulder, CO 80301, USA.
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- Accepted 22 June 2006.
- Received 15 May 2006.
- Revision received 20 June 2006.
- The Geological Society of America, Inc.
