Perthite gneisses and granulites formed in areas with isoclinal folding. Structurally the belt is composed of overturned west-vergent isoclinal fold trains, separated by thrusts. Most Yellowknife Supergroup metasediments are tightly folded (isoclinal) or occur in plunging anticlines. Isoclinal folds with east-striking axial planes become overturned to the north. The sedimentary basins have isoclinal folding and contain dacite volcaniclastic rocks, greywacke and argillite.