Abstract

Globally, detached evaporite basins and diapiric provinces are mostly concentrated along the Atlantic and Mediterranean-Red Sea systems, as large Mesozoic-Tertiary gravity slides. However, the late Paleozoic evaporitic Maritimes Basin in the east coast of Canada is an exception to this as it was detached following extensional collapse of the Appalachian orogen, prior to Atlantic Mesozoic rifting. In the Devonian-Carboniferous Maritimes Basin, thermal sag of a tectonically thinned crust resulted in marine flooding of an intracontinental basin in Visean time, and extensive evaporite precipitation. Extension mobilized Visean, Namurian, and syn-kinematic Westphalian units above the Ainslie Detachment, which occurs along the basal evaporite contact, forming an allochthonous raft measuring at least 67,000 km 2 . Contrasting contractional and extensional structural styles occur at the front and back ends of the allochthon. The front slid over the Hollow-Cabot normal fault into a half-graben, developing buckle folds, thrusts, and a diapir field that characterize the contractional domain. A drape syncline at the graben margin suggests displacement transfer between the Hollow-Cabot fault and Ainslie Detachment. The trailing edge of the raft features listric normal faults and stratigraphic gaps that characterize the extensional domain. Field relations demonstrate that the Ainslie Detachment was stratigraphically controlled by the Visean evaporites, producing thin-skinned deformation and gravity-slide-linking compressional and extensional regimes above the detachment.

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