TY - JOUR

T1 - Could the Norilsk Region Dolerite Sills Have Recorded Geomagnetic Field Reversals? Results of Mathematical Modeling

AU - Metelkin, D. V.

AU - Lavrenchuk, A. V.

AU - Mikhaltsov, N. E.

PY - 2019/11/1

Y1 - 2019/11/1

N2 - The possibility of reconstructing geologic events by identifying patterns in variations of the geomagnetic field related to reversals is one of the fundamental applications of paleomagnetism. The most detailed records of reversal events, whose duration averages 1-10 thous. years, are known from studies of flood basalts of large igneous provinces. At the same time, there have been recent publications presenting facts interpreted as records of geomagnetic reversals in intrusive bodies. Specifically, such data were obtained for relatively thin dolerite sills of the Ergalakh complex in the Norilsk region of the Siberian trap province that supposedly recorded the Permian-Triassic "Ivakin-Syvermin" reversal. This interpretation is based on the hypothesis of a slowly cooling intrusion, in which its apical parts magnetized in the Ivakin epoch of reversed polarity and the central parts-after the reversal in the Syvermin epoch of normal polarity. In this paper, using results of mathematical modeling, we discuss the validity of such assumptions and the potential attractiveness of subvolcanic intrusions for studies of geomagnetic reversals. We demonstrate that the duration of their cooling, including the most probable interval of magnetization is several orders of magnitude less than the duration of reversal transitions, and that the most probable cause of the occurrence of both polarities is the self-reversal effect.

AB - The possibility of reconstructing geologic events by identifying patterns in variations of the geomagnetic field related to reversals is one of the fundamental applications of paleomagnetism. The most detailed records of reversal events, whose duration averages 1-10 thous. years, are known from studies of flood basalts of large igneous provinces. At the same time, there have been recent publications presenting facts interpreted as records of geomagnetic reversals in intrusive bodies. Specifically, such data were obtained for relatively thin dolerite sills of the Ergalakh complex in the Norilsk region of the Siberian trap province that supposedly recorded the Permian-Triassic "Ivakin-Syvermin" reversal. This interpretation is based on the hypothesis of a slowly cooling intrusion, in which its apical parts magnetized in the Ivakin epoch of reversed polarity and the central parts-after the reversal in the Syvermin epoch of normal polarity. In this paper, using results of mathematical modeling, we discuss the validity of such assumptions and the potential attractiveness of subvolcanic intrusions for studies of geomagnetic reversals. We demonstrate that the duration of their cooling, including the most probable interval of magnetization is several orders of magnitude less than the duration of reversal transitions, and that the most probable cause of the occurrence of both polarities is the self-reversal effect.

KW - cooling dynamics

KW - dolerite sill

KW - geomagnetic reversals

KW - magnetization self-reversal

KW - mathematic modeling

KW - paleomagnetism

KW - RAPID ERUPTION

KW - MAGNETIZATION

KW - BASALTS

KW - STEENS MOUNTAIN

KW - STRATIGRAPHY

KW - SELF-REVERSAL

KW - SIBERIAN PLATFORM

KW - EVOLUTION

KW - PERMIAN-TRIASSIC TRAPS

KW - PALEOMAGNETISM

UR - http://www.scopus.com/inward/record.url?scp=85075995856&partnerID=8YFLogxK

U2 - 10.1134/S1069351319060041

DO - 10.1134/S1069351319060041

M3 - Article

AN - SCOPUS:85075995856

VL - 55

SP - 833

EP - 840

JO - Izvestiya, Physics of the Solid Earth

JF - Izvestiya, Physics of the Solid Earth

SN - 1069-3513

IS - 6

ER -