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Adam Maloof
Assistant Professor of Geosciences (Geology)

Department of Geosciences
213 Guyot Hall
Princeton University
Princeton, NJ 08544

Phone: (609) 258-2844
E-Mail: maloof@princeton.edu

Paleomagnetic data from 1.1 billion year old (Ga) basalts and gabbros from the mid-continental rift of North America, the Bahia State of Eastern Brazil, and the Umkondo igneous province of Southern Africa show a consistent inclination asymmetry between normal and reversed polarities. Specifically, the reverse polarity magnetic direction has a steeper inclination than the normal polarity direction. If the observed reversal asymmetry is considered an expression of a non-reversing 10-15% quadrupolar contribution to an otherwise reversing, geocentric axial dipole field, then a radical new Rodinian paleogeography can be constructed, and 1.1 Ga climate and tectonics will have to be critically reevaluated. Non-dipole fields are easy to simulate in geodynamo models, they are common on other planets, and they may even be present in some semi-modern reversal records on Earth. Identifying long-lived non-dipole components in the ancient magnetic field would have major implications for the way we understand heat flow across the core mantle boundary, mantle convection, and plate motions.

Currently, my group is conducting detailed geologic mapping and volcano-stratigraphy of the thick basaltic succession on the eastern shore of Lake Superior, where a stack of 1.1 Ga mid-continental rift lava and sediment preserve a record of multiple asymmetric paleomagnetic reversals. We are attempting to determine the absolute geochronological relationship between normal and reversed polarities by collaborating with Sam Bowring to attain precision U-Pb ages from rocks within each polarity zone of single stratigraphic sections, therefore avoiding the problems of correlation. In addition, we are studying polarity transitions within lava flows with an advanced suite of low-temperature rock magnetic tests to determine whether magnetic inclination or polarity is dependent on mineralogy.