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The Permian–Triassic boundary in Antarctica

Published online by Cambridge University Press:  06 June 2005

G.J. RETALLACK
Affiliation:
Department of Geological Sciences, University of Oregon, Eugene, OR 97403, USA
A.H. JAHREN
Affiliation:
Department of Earth and Planetary Sciences, Johns Hopkins University, 34th and N. Charles Streets, Baltimore, MD 21218, USA, [email protected]
N.D. SHELDON
Affiliation:
Department of Geological Sciences, University of Oregon, Eugene, OR 97403, USA
R. CHAKRABARTI
Affiliation:
Department of Earth and Environmental Sciences, University of Rochester, Rochester, NY 14627, USA
C.A. METZGER
Affiliation:
Department of Geological Sciences, University of Oregon, Eugene, OR 97403, USA
R.M.H. SMITH
Affiliation:
Department of Earth Sciences, South African Museum, PO Box 61, Cape Town 8000, South Africa

Abstract

The Permian ended with the largest of known mass extinctions in the history of life. This signal event has been difficult to recognize in Antarctic non-marine rocks, because the boundary with the Triassic is defined by marine fossils at a stratotype section in China. Late Permian leaves (Glossopteris) and roots Vertebraria), and Early Triassic leaves (Dicroidium) and vertebrates (Lystrosaurus) roughly constrain the Permian–Triassic boundary in Antarctica. Here we locate the boundary in Antarctica more precisely using carbon isotope chemostratigraphy and total organic carbon analyses in six measured sections from Allan Hills, Shapeless Mountain, Mount Crean, Portal Mountain, Coalsack Bluff and Graphite Peak. Palaeosols and root traces also are useful for recognizing the Permian–Triassic boundary because there was a complete turnover in terrestrial ecosystems and their soils. A distinctive kind of palaeosol with berthierine nodules, the Dolores pedotype, is restricted to Early Triassic rocks. Late Permian and Middle Triassic root traces are carbonaceous, whereas those of the Early Triassic are replaced by claystone or silica. Antarctic Permian–Triassic sequences are among the most complete known, judging from the fine structure and correlation of carbon isotope anomalies.

Type
Research Article
Copyright
© Antarctic Science Ltd 2005

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