HR: 16:15h
AN: GP44A-02    [Abstracts]
TI: Abrupt Shifts in the Position of the North Magnetic Pole From Arctic lake Sediments: Relationship to Archeomagnetic Jerks
AU: * Stoner, J S
EM: jstoner@coas.oregonstate.edu
AF: COAS, Oregon State University, Corvallis, OR 97331 United States
AU: Francus, P
EM: pfrancus@ete.inrs.ca
AF: Centre Eau, Terre et Environnement, INRS, Qu‚bec, Qu‚ G1K 9A9 Canada
AU: Bradley, R S
EM: rbradley@geo.umass.edu
AF: Department of Geosciences, University of Massachusetts, Amherst, MA 01003 United States
AU: Patridge, W
EM: patridge@geo.umass.edu
AF: Department of Geosciences, University of Massachusetts, Amherst, MA 01003 United States
AU: Abbott, M A
EM: mabbott1@pitt.edu
AF: Geology and Planetary Science, University of Pittsburgh, Pittsburgh, PA 15260 United States
AU: Retelle, M J
EM: mretelle@bates.edu
AF: Department of Geology, Bates College, Lewiston, ME 04240 United States
AU: Lamoureux, S
EM: lamoureux@lake.geog.queensu.ca
AF: Department of Geography, Queen's University, Kingston, ON K7L 3N6 Canada
AU: Channell, J E
EM: jetc@geology.ufl.edu
AF: Department of Geological Sciences, University of Florida, Gainesville, FL 32611 United States
AB: Historical observations document ~1100 km change in the position of the North Magnetic Pole (NMP) over the last century. This movement has accelerated over the last few decades to an astonishing 40 km/yr and along with the diminishing intensity of the dipole field has led to speculation of imminent reversal or excursion. Recently it has been shown that movement of the NMP is sensitive to small and rapid variations of the field known as Geomagnetic Jerks (Newitt et al., 2002; Mandea and Dormy 2003). These observations indicate that tracking the migration of the NMP provides a tracer of field variations allowing a more complete understanding of geomagnetic field behavior prior to historical observations. Reconstruction of the late Holocene paleomagnetic record from the Canadian High Arctic has been undertaken using u-channel paleomagnetic measurements from lakes in Ellesmere, Devon, Cornwallis and Bathurst Islands. At present the most complete records come from Ellesmere Island (Sawtooth Lake, 79°21 N, 83°56 W and Murray Lake, 81°34 N, 69°54 W) as these sediments have excellent magnetic properties, and preserve a strong, stable, single component magnetization. Multiple records have been obtained from each of these lakes and they possess independent age control based on varve chronologies. The paleomagetic record from several other lakes support observations from Sawtook and Murray Lakes, although they lack either independent age control or replicate-coring. These data help to establish the characteristics of late Holocene paleomagnetic secular variation (PSV) for the Canadian High Arctic for the last 2600 yrs. Correlations between sediment PSV records and historical observations demonstrate that the geomagnetic record is influenced by the position of the NMP, and that Arctic sediment magnetizations are sensitive to its movement. Over the last 2000 yrs, the PSV record documents at least 3 rapid (< 100 yrs) high amplitude NMP shifts that are much larger than anything observed in the historical record (the last 400 yrs). Abrupt shifts in the position of the NMP by thousands of kilometers appear to closely coincide with the three most recent archeomagnetic "jerks" of Gallet et al., (2003).
DE: 1522 Paleomagnetic secular variation
DE: 1530 Rapid time variations
DE: 1560 Time variations: secular and longer
SC: Geomagnetism and Paleomagnetism [GP]
MN: Fall Meeting 2005