Current-independent paleomagnetic declinations in flysch basins: A case study from the inner carpathians

Emo Márton, Maria Jeleńska, Antek K. Tokarski, Ján Soták, Michal Kováč, Ján Spišiak

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Abstract

Paleomagnetic declinations from the Inner Carpathian Paleogene Basin imply that the area rotated counterclockwise about 60°, during the Miocene[1]. The question may arise if the paleomagnetic declination could have been biased by the W-E directed turbidity currents prevailing in the basin causing an apparent counter-clockwise rotation of the paleomagnetic direction. The paleomagnetic results were obtained for fine grained strata, deposited in relatively calm water. Nevertheless, to confirm the paleomagnetic rotation, we needed evidence that flow activity on the magnetic grains was indeed insignificant in the beds yielding paleomagnetic results. Therefore, we carried out magnetic anisotropy measurements. Results of AMS (representing para and ferromagnetic minerals together) measurements, compared with paleomagnetic observations, demonstrate that well-clustered lineations at locality level and failure to define a paleomagnetic direction are coupled. Lineation, when observable, is flow parallel, suggesting that magnetic lineation in the Inner Carpathian flysch basins may be regarded as a good proxy for turbidity current direction. It is remarkable, however, that the well-defined paleomagnetic directions are observed for localities, where the magnetic fabric is not showing lineation on locality level. Moreover, the lineation direction of the ferromagnetic minerals alone (obtained by measuring the anisotropy of the remanence) is independent of that of the turbidity currents. Thus we can safely conclude that the Inner Carpathian flysch basin indeed was affected by 60° tectonic rotation, and the paleomagnetic vectors were not biased by paleocurrents.

Original languageEnglish
Pages (from-to)73-82
Number of pages10
JournalGeodinamica Acta
Volume22
Issue number1-3
DOIs
Publication statusPublished - Jan 1 2009

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Keywords

  • Flysch
  • Magnetic anisotropy
  • Paleomagnetic declination
  • Possible bias
  • Turbidity current

ASJC Scopus subject areas

  • Geophysics
  • Earth-Surface Processes

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