HR: 1330h
AN: S22A-0439    [PDF]
TI: Variations in Elastic Thickness in the Canadian Shield
AU: * Audet, P
EM: pascal@olympus.geotop.uqam.ca
AF: GEOTOP-UQAM-McGILL, Universit\'e du Qu\'ebec \`a Montr\'eal, CP 8888, succursale Centre-Ville, Montr\'eal, Qc, H3C 3P8 Canada
AU: Bourlon, E
AF: Environmental Earth Sciences Laboratory, St. Francis Xavier University, P.O. Box 5000, Antigonish, N-S B2G 2W5 Canada
AU: Mareschal, J
AF: GEOTOP-UQAM-McGILL, Universit\'e du Qu\'ebec \`a Montr\'eal, CP 8888, succursale Centre-Ville, Montr\'eal, Qc, H3C 3P8 Canada
AB: We have used different spectral methods (Blackman-Tukey, Multitaper, and Maximum Entropy) to determine from the coherence between Bouguer gravity and topography the variations of the effective elastic thickness ($T_e$) of the lithosphere in the Canadian Shield. These methods differ mostly by their spatial resolution (1,000 to 2,000km) determined by the width of the windows applied to the data sets to obtain the spectral estimates but yield comparable results and the maps of $T_e$ show similar trends. The highest resolution is obtained from the maximum entropy method. The Canadian Shield includes several geological provinces ranging in age from Archean to mid Proterozoic. The effective elastic thickness varies from $<$30km to $>100$km over distances comparable to the width of the moving window. There is no clear relationship between elastic thickness and age as high and low values of $T_e$ are found within each of the geological provinces. The map of $T_e$ does not show a clear geographic pattern with high elastic thickness values found near the edge as well as near the center of the continent.
DE: 8122 Dynamics, gravity and tectonics
DE: 8164 Stresses--crust and lithosphere
SC: Seismology [S]
MN: 2003 Fall Meeting