Heat flow variations in the Grenville Province, Canada

Heat flow and heat production data provide strong constraints on the composition and evolution of the continental crust. Four new heat flow and heat production data from the Grenville Province in Canada are presented and included in local and regional analyses of heat flow variations. Thirty heat flow data are now available in the Late Proterozoic Grenville Province, where the mean heat flow (41 ± 11 mW · m−2) does not differ from that in the Archean Superior Province (41 ± 9 mW · m−2). It is shown that varying crustal heat production or heat refraction effects account for most local heat flow variations. The average crustal heat production is lower than in the other Late Proterozoic provinces because the tectonic evolution of the Grenville promoted the emplacement of large mafic bodies. Statistical analyses of heat flow and heat production data in the Grenville Province, in the surrounding provinces (Canadian Appalachians and Superior Province) and in the Norwegian Shield indicate that, within each province, the range of heat flow and heat production variations attains 40 mW · m−2 and 2 μW · m−3 respectively. However, the patterns on the histograms are distinctive and are shown to be regulated by the vertical distribution of heat production. Crustal structure and composition of the Grenville Province and the Norwegian Shield account for similarities and differences in the heat flow and heat production patterns of the two areas. Mantle heat flow in the Grenville Province lies between 9 and 16 mW · m−2, as in the Superior Province and in the Norwegian Shield.