Annales de la Société géologique de Belgique Annales de la Société géologique de Belgique -  Volume 115 (1992)  Fascicule 2 - Devonian-Carboniferous boundary 

The age of the Devonian-Carboniferous boundary

Jonathan C. Claoué-Long, 
Research School of Earth Sciences, Australian National University, GPO Box, 4, Canberra ACT 2601, Australia.
P.J. Jones, 
Bureau of Mineral Resources, GPO Box 378, Canberra, ACT 2601, Australia.
John Roberts, 
Department of Applied Geology, University of New South Wales, Kensington, NSW 2033, Australia.

Abstract

The Devonian-Carboniferous boundary is now one of the most securely dated positions in the Phanerozoic column. Coincident with redefinition of the boundary, a thin volcanic layer has been identified 35 cm above the boundary in the Hasselbachtal section in Germany, now one of the auxiliary global stratotypes, and a tuff has been located at a similar biostratigraphic level in Australia. Ion microprobe zircon dating of the two horizons has yielded indistinguishable ages, and indicates 353.2 ± 4.0 Ma (2σ) as the age of the boundary.

Recent previous estimates of the age of this boundary have suggested dates with a spread of 25 Ma. A review of historical contraints shows that this uncertainty rested mainly upon biostratigraphic difficulty in correlating dated volcanics in terrestrial sediments with the type marine stratigraphy. Recognition of a dateable volcanic layer in the Hasselbachtal auxiliary stratotype eliminates this source of doubt. Future refinements of the age of the Devonian-Carboniferous boundary will depend on re-analysis of this uniquely placed volcanic, and this highlights the value of defining stratotypes in the vicinity of known dateable horizons.

Pour citer cet article

Jonathan C. Claoué-Long, P.J. Jones & John Roberts, «The age of the Devonian-Carboniferous boundary», Annales de la Société géologique de Belgique [En ligne], Volume 115 (1992), Fascicule 2 - Devonian-Carboniferous boundary, 531-549 URL : https://popups.uliege.be/0037-9395/index.php?id=1736.