HR: 1340h
AN: T23A-1211    [Abstracts]
TI: Very low heat flow near the center of the Canadian Shield
AU: * Levy, F
EM: levy@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, 4 Pl. Jussieu, Paris, 75252, France
AU: Mareschal, J
EM: mareschal.jean-claude@uqam.ca
AF: GEOTOP-UQAM-McGill, University of Quebec at Montreal, POB 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: Extrapolation of presently available heat flow measurements suggests that heat flow is very low in the northeastern part of the Canadian Shield over a region covering Hudson Bay, northern Quebec, and Labrador. The basement of this region includes several Archean blocks that were welded together during the PaleoProterozoic (ca. 1.8Ga). High seismic velocities to a depth of ~ 300km have been inferred for the same region. So far, the existence of a low heat flow region was based on extrapolation of trends in the extremely scarce data so far available. The presence of this region has been confirmed by new measurements obtained in the James Bay area, to the southeast and to the southwest of Hudson Bay, and at the tip of the Ungava peninsula, to the northeast. We shall present new heat flow and heat production measurements from deep boreholes at six sites in the Archean Superior Province and in the PaleoProterozoic Cape Smith Belt. The heat flow values determined so far range between 22 and 34 mW~m^-2 compared with a mean of 41 mW~m^-2 for the entire Superior Province. These lower than average heat flow values were measured over various rock types, including granitic rocks that are not depleted in radio-elements. Our preliminary interpretation thus requires low temperatures in the lithospheric mantle at the southern and eastern edges of Hudson Bay.
DE: 8103 Continental cratons
DE: 8130 Heat generation and transport
SC: Tectonophysics [T]
MN: 2007 Fall Meeting