Characterising the southern part of the Hearne Province: A forgotten part of Canada's shield revisited

The central Hearne Province extends into northeastern corner of Saskatchewan. It contains oceanic mafic volcanic rocks of the Ennadai Group that were intruded by juvenile tonalites at 2.71-2.70 Ga. The age and isotopic character of these tonalites contrasts markedly with those in the felsic orthogneiss complex of the southern Hearne Province. A comparison of plutonic suites and supracrustal assemblages of the central and southern Hearne Provinces suggests that there is heterogeneity between the two entities. Analysis of geophysical data, coupled with existing geological maps, suggest that an important tectonic boundary separates them. The current age relationships in the central and southern parts of the Hearne province imply that the two were juxtaposed after 2.60 Ga; however, the time of suturing remains equivocal.