Downward continuation of heat flow density data and thermal regime in Eastern Canada

Abstract

Heat flow density (HFD) data from Eastern Canada were analyzed by downward continuation. The data cover parts of the Superior and Grenville provinces of the Canadian Shield, and parts of the Appalachian orogen. The downward continuation eliminates the effect of shallow crustal radiogenic heat production and better reveals differences in the thermal regime of deeper origin. The analysis shows that the deep heat flow beneath the Superior and Grenville provinces is low and the temperature in the lower crust is also low. The thermal regime of the crust changes markedly across a boundary that follows the St Lawrence River. Surface heat flow and heat production are markedly higher in the Appalachian Province. With much higher temperature and heat flow, the thermal regime in the Appalachian lower crust is also distinctly different from that of the shield. Temperature and heat flow increase eastward toward the Atlantic margin.