HR: 0800h
AN: T31B-0477    [Abstracts]
TI: The Magnetic Signature of Zones of Continental Collision
AU: * Purucker, M E
EM: purucker@geomag.gsfc.nasa.gov
AF: Raytheon at Planetary Geodynamics Lab, Goddard Space Flight Center NASA, Greenbelt, MD 20771, United States
AU: Whaler, K A
EM: kathy.whaler@ed.ac.uk
AF: School of GeoSciences, University of Edinburgh, Edinburgh, EH9 3JW, United Kingdom
AB: Near-surface and satellite maps of the crustal component of the magnetic field can be interpreted in terms of thermal conditions at depth because the magnetic properties of rocks depend on their temperature. Observations related to continental deformation at diffuse plate boundaries are often considered in relation to three length scales: the thickness of the seismogenic upper crust, the entire continental crust, and the mechanical lithosphere. The lower boundary of the magnetic crust coincides with the Moho, or in the presence of an elevated geotherm, with the Curie isotherm. New global perspectives on the magnetic signature of zones of continental collision are afforded by the recently published Magnetic Anomaly Map of the World (Purucker, 2007, EOS, 88, 263), the MF-5 satellite magnetic field (Maus et al., 2007, Gcubed), and NASA's ST-5 constellation mission in 2006. The thickness of the magnetic crust can be estimated by integrating the MF-5 satellite magnetic field into the 3SMAC compositional and thermal model of the lithosphere, and a minimum estimate of the magnetization can be estimated using a Greens function approach. We compare our magnetic maps with the diffuse plate boundary maps of Gordon (1998) and Dumoulin et al. (1998). The diffuse plate boundary zones exhibit intermediate (22-31 km) magnetic thicknessses, significantly less than those of the adjacent stable plate. The diffuse NE Asia plate boundary zone, from the Lena River delta to the Sea of Okhotsk, is especially well- expressed in both satellite and near-surface magnetic maps.
DE: 1545 Spatial variations: all harmonics and anomalies
DE: 8110 Continental tectonics: general (0905)
DE: 8124 Earth's interior: composition and state (1212, 7207, 7208, 8105)
DE: 8150 Plate boundary: general (3040)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting