The Sudbury Huronian heat flow anomaly, Ontario, Canada

•High heat flow in Sudbury region due to high heat production in Huronian sediments.•Sudbury igneous complex result of mixing of Superior and Huronian upper crustal rocks.•Variations in Grenville Front tectonic style related to thermal regime and heat production.•Crustal heat production must be accounted for in interpretation of geoneutrino observations.

New measurements of the surface heat flux and radiogenic heat production in deep boreholes at 8 different sites are added to 10 older data to determine the heat flow field around the Sudbury basin, Ontario, Canada. This structure straddles the boundary between the Archean Superior Province to the North and the PaleoProterozoic Southern Province to the South, which terminates against the Grenville Front. The structure, that includes the Sudbury Igneous Complex (SIC), was created by a meteorite impact ca. 1.85 Ga. The mean value of the heat flux (50 mW m−2) is higher than that for the Superior Province (40 mWm-2). Heat flow values are hardly perturbed by the presence of the SIC and require a regional enhancement of heat production in the upper crust with respect to the average Superior, due mostly to the enriched Huronian metasediments of the Southern Province. The average radiogenic heat production of SIC lithologies (1.2 μW m-3) is higher than that of the local Archean basement, indicating that the impact melt sheet was partly derived from Huronian sediments. Local variations in heat flux can be related to heat production differences between the Abitibi upper crust and the Huronian metasediments as well as thrusting and tectonic thickening in the Southern Province. The higher than average values of heat flux and crustal heat production in the Southern Province imply elevated crustal temperatures and a weak rheology in the lower crust at the time of the meteorite impact and of the contemporaneous Penokean orogeny. Large variations of crustal thermal structure at the edge of the Superior Province may have led to along-strike differences in the style and extent of thrusting during the Grenville Orogeny.