In the central Superior province of the Canadian Shield, a 120-km-wide transition from the low-grade Michipicoten greenstone belt to the high-grade Kapuskasing structural zone represents an oblique section through some 20 km of Archean crust, uplifted along a northwest-dipping thrust fault. The restored vertical section through the upper and middle crust consists of three megalayers with undulating boundaries: (1) 0 to < 10 km, a metavolcanic-metasedimentary succession (“greenstone belts”) with discordant plutons; (2) < 10 to ∼20 km, tabular batholiths of gneissic and xenolithic tonalite and granodiorite; and (3) from 20 to >25 km, a high-grade heterogeneous gneissic assemblage, in part older than the upper supracrustal succession.

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