Paleomagnetic Field Properties at High Southern Latitude, Erebus Volcanic Province, Antarctica
Abstract
We present new paleointensity and paleodirectional data from 100 volcanic sites in the Erebus Volcanic Province (EVP), Antarctica and twenty-one new age determinations by the 40Ar/39Ar incremental heating method. The new EVP data are combined with previously published paleomagnetic and geochronological results, providing a total of 141 sites. 91 sites have been dated and span 0.03 to 13.42 Ma. The 125 high-quality EVP directional data selected from the merged dataset have a non-Fisherian distribution and a mean direction with an inclination anomaly of ~3°, but the 95% confidence limit includes the prediction from a geocentric axial dipole. Virtual geomagnetic pole (VGP) dispersion is high compared with values from mid to low-latitude regions regardless of the criterion used to determine transitional fields. With VGP latitude cut-off at 45° the dispersion of 24.0 ± 2.2° for the combined 0-5 Ma EVP dataset is consistent with earlier high latitude data and paleosecular variation (PSV) in Model G but not with some more recent statistical PSV models. The mean EVP paleointensity of 31.5 ± 2.4° μT, derived from modified Thellier-Thellier experiments is about half the current value at McMurdo. This result is independent of our data selection criteria. High VGP dispersion and low intensity values support the global observation of anti-correlation between directional variability and field strength. Simulations of time-varying dipole strength show that uneven temporal sampling may bias the mean EVP intensity estimate, but the possibility of persistently anomalous field behavior at high latitude cannot be excluded.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFMGP11A0701L
- Keywords:
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- 1521 Paleointensity;
- 1522 Paleomagnetic secular variation;
- 1532 Reference fields: regional;
- global