Diese Seite ist aus Gründen der Barrierefreiheit optimiert für aktuelle Browser. Sollten Sie einen älteren Browser verwenden, kann es zu Einschränkungen der Darstellung und Benutzbarkeit der Website kommen!
Geophysics Homepage
Search:
Log in
print

A reversal of the Earth's magnetic field recorded in mid-Miocene lava flows of Gran Canaria: Paleointensities

Leonhardt, R., and H. C. Soffel (2002), A reversal of the Earth's magnetic field recorded in mid-Miocene lava flows of Gran Canaria: Paleointensities, Journal of Geophysical Research-Solid Earth, 107(B11), doi:10.1029/2001JB000949.

Abstract
[1] An extensive paleointensity study was carried out on an approximately 14.1 Myr old reverse-to-normal transition of the geomagnetic field. A total of 188 samples from a volcanic sequence on Gran Canaria (Canary Islands) were subjected to Thellier-type paleointensity determinations. The paleodirectional results of this sequence are reported by Leonhardt et al. [2002]. A modified Thellier technique, which facilitates the recognition of MD tails and the formation of new magnetic remanences with higher blocking temperatures than the actual heating step, was used on the majority of the samples. We obtained reliable paleointensity results for 35% of the 87 sampled lava flows. In general, the obtained field intensities are lower than expected for the mid-Miocene. This observation is very likely related to a long-term reduction of the field close to transitions. Very low paleointensities with values <5 μT were obtained during an excursion, preceding the actual transition, and also close to significant changes of the local field directions. These are interpreted as nondipolar components becoming dominant for short periods and provoking a rapid change of field directions. During the transition, 15 successive lava flows recorded similar local field directions corresponding to a cluster of virtual geomagnetic poles close to South America. Chronologically, within this cluster, the paleointensity increases from about 9 to 28 μT followed by a decrease back to approximately 9 μT. This variation of paleointensity between lava flows with similar direction indicates independent records of the geomagnetic field and gives strong evidence for a stable transitional state that lasted a significant period.
BibTeX
@article{id166,
  author = {R. Leonhardt and H. C. Soffel},
  journal = {Journal of Geophysical Research-Solid Earth},
  number = {B11},
  title = {{A reversal of the Earth's magnetic field recorded in mid-Miocene lava flows of Gran Canaria: Paleointensities}},
  volume = {107},
  year = {2002},
  language = {en},
  doi = {10.1029/2001JB000949},
}
EndNote
%0 Journal Article
%A Leonhardt, R.
%A Soffel, H. C.
%D 2002
%N B11
%V 107
%J Journal of Geophysical Research-Solid Earth
%T A reversal of the Earth's magnetic field recorded in mid-Miocene lava flows of Gran Canaria: Paleointensities
ImprintPrivacy PolicyContact
Printed 25. Aug 2019 09:42