Examples of Archean shield areas from Canada and Australia are used to demonstrate a consistent orthogonality in trend between late Archean mafic dikes (~2.5 Ga old) and the structure of granite–greenstone terrains whose orogenic history terminated no more than about 0.2 Ga prior to dike injection. The simplest explanation of this relationship is that the regional structural grain of the granite–greenstone terrains was formed by horizontal crustal compression, and that the direction of maximum horizontal stress remained unchanged up to and including the time of dike emplacement.

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