A detailed paleomagnetic record between 2.1 and 2.75 Ma at IODP Site U1314 in the North Atlantic: Geomagnetic excursions and the Gauss-Matuyama transition - INSU - Institut national des sciences de l'Univers Access content directly
Journal Articles Geochemistry, Geophysics, Geosystems Year : 2012

A detailed paleomagnetic record between 2.1 and 2.75 Ma at IODP Site U1314 in the North Atlantic: Geomagnetic excursions and the Gauss-Matuyama transition

Masao Ohno
  • Function : Author
Tatsuya Hayashi
  • Function : Author
Fumiki Komatsu
  • Function : Author
Fumi Murakami
  • Function : Author
Meng Zhao
  • Function : Author
Yohan Guyodo
Gary Acton
  • Function : Author
Helen F. Evans
  • Function : Author
Toshiya Kanamatsu
  • Function : Author

Abstract

This study investigated the detailed geomagnetic field variation between 2.1 and 2.75 Ma from a sediment core (IODP Site U1314) with high sedimentation rate (≥10 cm/kyr) and good age control. Characteristic remanent magnetization directions were well resolved by stepwise alternating field demagnetization. As a proxy of relative paleointensity, natural remanent magnetization (NRM) normalized by anhysteretic remanent magnetization (ARM) was used after testing that the influence of magnetic interaction in ARM is negligible. As a result, the following features of the geomagnetic field in the studied period have been revealed. During the transition of the Gauss-Matuyama (G-M) reversal and the Réunion Subchron, the paleointensity decreased to the value lower than 20% of the average intensity in the whole studied interval. In addition to these lows, eight paleointensity lows were found associated with large directional changes that satisfy the definition of a geomagnetic excursion. Four of these have ages close to ages reported for geomagnetic excursions in prior studies, whereas the other four excursions have not previously been observed. In our results, we confirm that the G-M transition occurred in marine isotope stage 103 even if we consider the shift in depth due to the lock-in process of magnetic particles. The temporal variation in paleointensity showed asymmetric behavior associated with the G-M transition, with a gradual decrease prior to the transition and a rapid recovery after the transition.
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insu-03583351 , version 1 (22-02-2022)

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Masao Ohno, Tatsuya Hayashi, Fumiki Komatsu, Fumi Murakami, Meng Zhao, et al.. A detailed paleomagnetic record between 2.1 and 2.75 Ma at IODP Site U1314 in the North Atlantic: Geomagnetic excursions and the Gauss-Matuyama transition. Geochemistry, Geophysics, Geosystems, 2012, 13, p. 410-432. ⟨10.1029/2012GC004080⟩. ⟨insu-03583351⟩
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