Low mantle heat flow at the edge of the North American continent, Voisey Bay, Labrador

Heat flow measurements in 4 deep drillholes near Voisey Bay, Labrador, have yielded the lowest value ever reported in the Canadian Shield, 22 mW m(-2) . This very reliable-estimate is also one of the lowest continental heat fl ow values world wide. It requires the crust to be very poor in radioelement s in this part of the Archean Nain Province. It also strongly supports the view that mantle heat flow is low (< 15 mW m(-2)) throughout the Canadian S hield, with no trend of increasing mantle heat flaw near the edges of the c ontinent. It also raises questions about the controlling mechanism for rift ing and the opening of the Labrador Sea at 100 Ma.