Eastern Superior Province, Abitibi Subprovince
The Abitibi subprovince tectono-stratigraphic evolution is explained in terms of oceanic geodynamic settings from plateau, to arc and rift environments. The Abitibi subprovince has been subdivided into three domains with overlapping tectonostratigraphic histories. In the northern Abitibi, volcanic assemblages are mainly 2.735-2.72 Ga and associated with layered intrusions, whereas volcanic rocks of 2.71-2.695 Ga are restricted to the southern Abitibi. The southern Abitibi has relatively young sedimentary-volcanic deposits including ca. 2.69 Ga greywackes of the Porcupine Group and 2.677-2.673 Ga conglomeratic and alkaline volcanic rocks of the Timiskaming Group. The central zone is dominated by plutonic rocks.
The Opatica belt in the south divides the Abitibi belt to the north and consists of units ranging from 2.82 Ga tonalite, through 2.77-2.70 Ga. tonalite-granodiorite, to 2.68 Ga granite and pegmatite. Polyphase deformation includes early, west-verging shear zones (<2.72 Ga), overprinted by 2.69-2.68 Ga south-vergent structures.
The Opinaca belt is characterized by metagreywacke, derived migmatite and granite. Polydeformed schists occur at the belt margins, whereas the interior portions are metamorphosed to amphibolite and granulite facies. These rocks are cut by the 2.67 Ga Broadback River granite. (Percival, 2006).
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