Secular geomagnetic variations and volcanic pulses in the Permian-Triassic traps of the Norilsk and Maimecha-Kotui provinces |
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Authors: | V E Pavlov F Fluteau R V Veselovskiy A M Fetisova A V Latyshev |
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Institution: | 1.Schmidt Institute of Physics of the Earth,Russian Academy of Sciences,Moscow,Russia;2.Institute of Earth Physics of Paris (IPGP),Paris,France;3.Faculty of Geology,Moscow State University,Moscow,Russia |
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Abstract: | Detailed paleomagnetic studies have shown that the effusive Permian-Triassic traps in the Kotui River valley were formed as
the result of volcanic activity, which occurred in the form of volcanic pulses and individual eruptions with net duration
of at most 7000–8000 years, excluding the periods of volcanic quiescence. According to the analysis of the paleomagnetic data
earlier obtained by Heunemann and his coauthors 2004b] on the Abagalakh and Listvyanka sections in the Norilsk region, those
geological units were formed during 25 volcanic pulses and separate eruptions, which all lasted up to 8000 years altogether,
whereas the total time of formation (including the periods of volcanic quiescence) exceeded 10000–100000 years for the Norilsk
section and was probably a bit shorter for the Kotui section. Comparison of the positions of virtual geomagnetic poles calculated
for the Norilsk and the Kotui sections provides no grounds to suggest that these sections were formed at different geological
times. The scatter in the positions of the virtual geomagnetic poles (VGP) for the directional groups and individual directions
(58 altogether) jointly for the two sections (more than 160 lava flows) indicates that the secular geomagnetic variations
at the Permian-Triassic boundary had similar amplitudes to those that occurred in the past 5 Ma. |
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