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Russian Geology and Geophysics

2022 year, number 2

Low Geomagnetic Field Paleointensity on the Permian-Triassic Boundary from Study of the Kuznetsk Basin Traps (Southern Siberia)

A.A. Eliseev1,2, V.V. Shcherbakova3, D.V. Metelkin1,2, N.E. Mikhal’tsov1,2, G.V. Zhidkov3, V.V. Abashev1,2, A.M. Rogov4
1Novosibirsk State University, Novosibirsk, Russia
2Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
3Borok Geophysical Observatory, department of Schmidt Institute of Physics of the Earth, Russian Academy of Sciences, Borok, Russia
4Kazan Federal University, Institute of Geology and Petroleum Technologies, Kazan, Russia
Keywords: Paleointensity, Thellier-Coe method, Mesozoic Dipole Low, Kuznetsk basin, Mal’tsevskaya Formation, Siberian trap province

Abstract

Here we report the first data on the absolute intensity value of the geomagnetic field on the Permian-Triassic boundary from basalts of the Kuznetsk basin. The latter are considered as one of the manifestations of the initial stage of trap magmatism during the formation of the Siberian large igneous province. The good preservation of information on the ancient geomagnetic field in the Mal’tsevskaya Formation basalts is due to the presence of small single domain and pseudo-single domain grains of primary magmatic titanomagnetite in the groundmass. The paleointensity values obtained following the Thellier-Coe method correspond to the generally accepted criteria of reliability and indicate that the geomagnetic field intensity during the formation of the Kuznetsk basin traps on the Permian-Triassic boundary was almost an order of magnitude lower than the present-day one. Moreover, the mean values of the virtual dipole moment for the Kozhukhta and the Vlasov units in the lower and middle Mal’tsevskaya Formation ((1.9 ± 0.6) × 1022 A × m2 and (1.1 ± 0.7) × 1022 A × m2, respectively) are in good alignment with determinations of the paleointensity during the accumulation of the Ivakinsky Formation of the Norilsk Region in the Siberian province, which confirms the accuracy of traditional regional correlations.