Paleomagnetism and magnetostratigraphy of the traps from Western Taimyr (northern Siberia) and the Permo-Triassic crisis

The Siberian traps were emplaced near the Permo-Triassic boundary and are among the largest continental igneous provinces. A 1750 m thick section of traps from the western Taimyr (72.9°N, 84°E) has been sampled. This section is equivalent to the lower and middle part of the total Siberian traps section. Thirty-one oriented hand samples were studied and demagnetised by alternating fields and heating cycles. A stable characteristic component passes the fold test and is thought to be primary. The mean direction is D = 84 °, I = 75 ° with α95 = 10 ° (N = 29) and the corresponding pole is 59°N, 150°E. The bottom part (660 m) is of reversed polarity, the middle part (900 m) is normal and the uppermost level (150 m) is mixed. Correlations with reference Permo-Triassic magnetostratigraphic timescales are discussed. The most probable correlation indicates an age quite close to the Permian/Triassic boundary and a duration for the volcanism of less than 1 m.y. The data are therefore consistent with the hypothesis that this volcanism triggered the Permian/Triassic crisis.