Are Paleomagnetic Records From U-Channels Appropriate for Studies of Reversals and Excursions? - INSU - Institut national des sciences de l'Univers Accéder directement au contenu
Article Dans Une Revue Geochemistry, Geophysics, Geosystems Année : 2018

Are Paleomagnetic Records From U-Channels Appropriate for Studies of Reversals and Excursions?

Résumé

Sampling of sediment cores using plastic U-channels has made possible the acquisition of detailed records of paleomagnetic secular variation, geomagnetic polarity, environmental magnetic studies, and relative paleointensity over the past several million years. U-channel measurements provide the great advantage of rapid measurements of long sediment cores, but the signal resolution is attenuated by the response function of the magnetometer sensors, which therefore restrains the recovery of rapid and large-amplitude field changes. Here we focus on the suitability of the dynamics of reversals and excursions derived from U-channel measurements. We compare successive individual paleomagnetic directions of 1.5 cm × 1.5 cm × 1.5 cm cubic discrete samples with those of a 1.5-m equivalent U-channel sample train obtained by placing the samples adjacent to each other. We use varying excursion and transition lengths and generate transitional directions that resemble those of the most detailed paleomagnetic records. Excursions with opposite polarity directions recorded over less than 7.5 cm are barely detected in U-channel measurements. Regarding reversals, U-channel measurements smooth the signal of low-resolution records and generate artificial transitional directions. Despite producing misleading similarities with the overall structure of transition records, longer transitional intervals fail also to reproduce the complexity of field changes. Finally, we test the convolution of magnetization by different response functions. The simulation reveals that even small response function changes can generate significant differences in results.
Fichier principal
Vignette du fichier
Philippe_et_al-2018-Geochemistry,_Geophysics,_Geosystems.pdf (2.33 Mo) Télécharger le fichier
Origine : Fichiers éditeurs autorisés sur une archive ouverte
Loading...

Dates et versions

insu-02399950 , version 1 (09-12-2019)

Identifiants

Citer

Édouard G H Philippe, Jean-Pierre Valet, Guillaume St-Onge, Anojh Thevarasan. Are Paleomagnetic Records From U-Channels Appropriate for Studies of Reversals and Excursions?. Geochemistry, Geophysics, Geosystems, 2018, ⟨10.1029/2018GC007803⟩. ⟨insu-02399950⟩
23 Consultations
57 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More