On low-latitude virtual geomagnetic poles in Icelandic basalt lava sequences

In two paleomagnetic studies from the Neogene lava sequences of Iceland pub lished in 1977, of the order of 10% of the reliably determined remanence di rections corresponded to virtual pole positions below 40 degrees latitude. This was a larger proportion than found in most other volcanic locations. T o explain it, Harrison [Harrison, C.G.A., 1980. Secular variation and excur sions of the Earth's magnetic field. J. Geophys. Res. 85, 3511-3522] sugges ted that some 10% of the observed virtual geomagnetic poles (VGP) from Icel and might be distributed at random over the globe. These ''random poles" ca n be envisaged as dating from periods when the geomagnetic field is weak an d dominated by variable non-dipole terms. Much additional data on remanence directions and intensities has been collected since then, and the present study analyses results from over 3500 lava flows in Iceland. The relative f requency and strength of virtual dipoles in this collection vary with the p ole latitude in a similar way as in the collection studied by Harrison. Nor malizing of remanence intensity data by the use of anhysteretic remanence ( ARM) may improve the resolution of this type of analysis. (C) 1999 Elsevier Science B.V. All rights reserved.