Seven thousand year duration for a geomagnetic excursion constrained by 230Thxs

Abstract

The duration of geomagnetic excursions may provide important information about the geodynamo. It has proven difficult, however, to assess the exact duration of both excursions and reversals. We combine high-resolution paleomagnetic records from marine sediments with measurements of the 230Thxs flux to the seafloor in order to better constrain the duration of the Iceland Basin Excursion (IBE). We final the duration of the IBE to be ∼7-8 kyr, implying that it is considerably longer than previous estimates for the Laschamp Excursion (∼2 kyr), and more similar in duration to that of full polarity reversals. There may not be, therefore, a characteristic timescale for transitional field configurations that distinguishes excursions from reversals. Copyright 2007 by the American Geophysical Union.