HR: 08:30h
AN: GP41A-03    [Abstracts]
TI: Preliminary paleointensity investigation of Iron Age pottery shards from southern Africa
AU: * Wendt, A K
EM: anna@earth.rochester.edu
AF: University of Rochester, Department of Earth & Environmental Sciences, 227 Hutchison Hall, Rochester, NY 14627, United States
AU: Tarduno, J A
EM: john@earth.rochester.edu
AF: University of Rochester, Department of Earth & Environmental Sciences, 227 Hutchison Hall, Rochester, NY 14627, United States
AU: Cottrell, R D
EM: rory@earth.rochester.edu
AF: University of Rochester, Department of Earth & Environmental Sciences, 227 Hutchison Hall, Rochester, NY 14627, United States
AU: Watkeys, M K
EM: watkeys@ukzn.ac.za
AF: School of Geological Sciences, University of KwaZulu-Natal, Durban, 4041, South Africa
AU: Huffman, T N
EM: Thomas.Huffman@wits.ac.za
AF: School of Archaeology, Geography and Environmental Studies, University of the Witwatersrand, Johannesburg, 2050, South Africa
AB: The intensity of Earth's magnetic dipole magnetic field has been rapidly decaying over the last 150 years. This decline is well documented by magnetic observatory data, and if it were to continue, the dipole field would be nonexistent in a few millennia. Recent studies have suggested that the decay commenced at approximately 1840, whereas the dipole field was of nearly constant strength from 1590 to 1840. These suggestions rely on an analysis of global archeomagnetic results. However, there are few results for Southern Hemisphere sites. To obtain a better spatial view of the history of the geodynamo during this interval, we are studying pottery shards from several southern Africa sites (including the Mapungubwe cultures of the Limpopo area). Preliminary magnetic hysteresis data (and first-order reversal curves) measured using a Princeton Measurements Alternating Gradient Force Magnetometer and P2 probes, Curie temperature determinations measured using a Kappabridge K4S Susceptibility Bridge, and XRD data indicate that some of the shards contain magnetic minerals suitable for paleointensity analyses. We will compare several methods of paleointensity determination, including the Thellier-Coe method (in an Argon atmosphere) and multiple specimen approaches, and examine these values versus model paleointensity predictions for the field area.
DE: 1503 Archeomagnetism
DE: 1521 Paleointensity
DE: 1540 Rock and mineral magnetism
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Fall Meeting