HR: 1330h
AN: S22A-0437    [PDF]
TI: Heat flow, thickness, and strength of the lithosphere in the Canadian Shield
AU: * Mareschal, J
EM: jcm@olympus.geotop.uqam.ca
AF: GEOTOP-UQAM-McGill University of Quebec at Montreal, P.O.B. 8888, sta "downtown", Montreal, QC H3C3P8 Canada
AU: Jaupart, C
EM: cj@ccr.jussieu.fr
AF: Institut de Physique du Globe de Paris, 4 Pl Jussieu, Paris, 75252 France
AB: The effective elastic thickness of the lithosphere ($T_e$) is estimated from the coherence between Bouguer gravity and topography. The spatial resolution is low (on the order of 1,000km) because of the size of the windows needed to determine the spectra. Within the the Canadian Shield, $T_e$ varies significantly (from $<$ 40 to $>$100km) over distances on the order of 1,000km. Elastic thickness variations are observed within each of the provinces in the Shield and exhibit no geographic trend.\\ More than 300 heat flow values are available for the southern part of the Canadian Shield. The mean surface heat flow is the same for all the provinces in the Shield ($41 \pm 10 (\sigma) \mathrm{mW~m^{-2}}$), but there are marked differences between sub-provinces characterized by different rock composition and mean crustal heat production. The heat flow and effective elastic thickness maps of the Shield appear to be negatively correlated with $T_e$ highest ($>$120km) in the areas where heat flow is lowest ($\approx 32 \mathrm{mW~m^{-2}}$). From the heat flow and heat production data, we have calculated thermal models and rheological profiles of the crust and lithosphere. The results show that most of the observed variations in $T_e$ in the Canadian Shield can be accounted for by differences in thermal regime.
DE: 7218 Lithosphere and upper mantle
DE: 8122 Dynamics, gravity and tectonics
DE: 8130 Heat generation and transport
DE: 8159 Rheology--crust and lithosphere
SC: Seismology [S]
MN: 2003 Fall Meeting