(Lisa Tauxe, Cathy Constable, Catherine Johnson, and Hubert Staudigel )
Current models of the time averaged geomagnetic field have small but significant long term departures from a geocentric axial dipole. The models shown to the right (from Johnson and Constable, 1997) are based on records of the ancient geomagnetic field stored in lava flows from the last five million years. These models are based on limited records, and revealed the need for a concerted effort to get new paleomagnetic data with improved geographic and temporal distribution. The Time-averaged Field Investigations (TAFI) project was launched in 1998 to help address this problem.
The SIO paleomagnetic/geomagnetic group has taken part in the multi-institutional TAFI project to collect reliable data of the geomagnetic field over the last 5 million years to build a new time averaged field model. The goal is to collect and analyze samples from lava flows erupted over the last 5 million years from a pole to pole transect. The locations that Scripps was responsible are shown to the left. Other groups from the University of Florida , University of Masachussetts (Amherst), University of Alaska (Fairbanks), University of California (Santa Cruz and Santa Barbara), and the University of Wisconsin sampled and/or dated lava flows from the Aleutians, Nunivak, British Columbia, Mexico, South America, and Ecuador. In total 873 paleomagentic directions have been obtained from lavas in 17 different locations.
Related Publications:
Johnson, C.L., J.R. Wijbrans, C.G. Constable, J. Gee, H. Staudigel, L. Tauxe, V, Forjaz, & M.Salgueiro, 40Ar/39Ar ages and paleomagnetism of Sao Miguel lavas, Azores, Earth Planet. Sci. Lett. 160, 637-649, 1998.
Tauxe, L., Staudigel, H., Wijbrans, J.R., Paleomagnetism and 40Ar/39Ar ages from La Palma in the Canary Islands, Geochem. Geophys. Geosyst., 1, 2000GC000063 [6717 words, 8 figures, 3 tables, 1 appendix], 2000.
Tauxe, L., Constable, C., Johnson, C.L., Miller, W.R., Staudigel, H., Paleomagnetism of the southwestern U.S.A. recorded by 0-5 Ma igneous rocks, Geochem., Geophys., Geosyst., DOI 10.1029/2002GC000343, 2003.
Johnson, C.L., Constable, C.G., and Tauxe, L., Mapping long-term changes in the Earth's magnetic field, Science, 300, 2044-2045, 2003.
Tauxe, L., Gans, P., Mankinen, E.A., Paleomagnetic and 40Ar/36Ar ages from Brunhes and Matuyama aged volcanics near McMurdo Sound, Antarctica, Geochem., Geophys., Geosyst., Q06H12, doi:10.1029/2003GC000656, 2004.
Tauxe, L., Kent, D.V., A simplified statistical model for the geomagnetic field and the detection of shallow bias in paleomagnetic inclinations: Was the ancient magnetic field dipolar?, in Timescales of the Paleomagnetic field, Channell, J.E.T. et al., eds., Geophysical Monograph, 145, 101-116, 2004.
Tauxe, L., Luskin, C., Selkin, P., Gans, P., Calvert, A., Paleomagnetic results from the Snake River Plain: Contribution to the global time averaged field database, Geochem., Geophys., Geosyst., 5, Q08H13, doi:10.1029/2003GC000661, 2004.
Johnson, C.L., C.G. Constable, L. Tauxe, et al., Recent investigations of the 0-5 Ma geomagnetic field recorded by lava flows, Geochem., Geophys., Geosyst., submitted November 2006.
SIO contributions to the TAFI project have been funded by the NSF through the Geophysics and Polar Programs (Grant Numbers EAR-941204, EAR-9805164, EAR-0337712, OPP-0229403, OPP-0538392).
This page last updated 11/18/2006 by Cathy Constable (cconstable@ucsd.edu)