A view into the Cretaceous geomagnetic field from analysis of gabbros and submarine glasses

Roi Granot, Lisa Tauxe, Jeffrey S. Gee, Hagai Ron

Research output: Contribution to journalArticlepeer-review

30 Scopus citations

Abstract

The nature of the geomagnetic field during the Cretaceous normal polarity superchron (CNS) has been a matter of debate for several decades. Numerical geodynamo simulations predict higher intensities, but comparable variability, during times of few reversals than times with frequent reversals. Published geomagnetic paleointensity data from the CNS are highly scattered suggesting that additional studies are required. Here we present new paleointensity results from 18 sites collected from the lower oceanic crust of the Troodos ophiolite, Cyprus (92.1 Ma old). Together with recently published data from the Troodos upper crust we obtain three independent paleointensity time-series. These sequences reveal quasi-cyclic variations of intensities about a mean value of 54 ± 20 Z Am2, providing insight into the fluctuating nature of the Cretaceous magnetic field. Our data suggest the CNS field was both weaker and more variable than predicted by geodynamo simulations. The large amplitudes of these variations may explain the wide range of dipole moments previously determined from the CNS.

Original languageEnglish
Pages (from-to)1-11
Number of pages11
JournalEarth and Planetary Science Letters
Volume256
Issue number1-2
DOIs
StatePublished - 15 Apr 2007
Externally publishedYes

Keywords

  • Cretaceous normal polarity superchron
  • Troodos ophiolite
  • geomagnetic field
  • paleointensity
  • paleomagnetism

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