Salt tectonics in an intracontinental transform setting: Cumberland and Sackville basins, southern New Brunswick, Canada

Abstract

AbstractSalt tectonics have markedly influenced the rapid evolution of the Upper Palaeozoic Cumberland Basin of Atlantic Canada, including the ca. 5 km‐thick Mississippian – Pennsylvanian stratigraphic succession exposed along the UNESCO World Heritage coastline at Joggins, Nova Scotia. A diapiric salt wall is exposed in the Minudie Anticline to the north of the Joggins section on the Maringouin Peninsula of New Brunswick, which corresponds to the fault‐bounded northern margin of the Cumberland Basin. The salt wall is of Visean evaporites of the Windsor Gp that originally were buried by red‐beds of the Mabou Gp in the Serpukhovian, and later by fluvial and floodplain strata (Boss Point Fm, Cumberland Gp) in the Yeadonian (mid‐Bashkirian, Early Pennsylvanian). Folds and faults in the Boss Point and overlying basal Little River formations are truncated by an angular unconformity at the base of overlying red‐beds of the Grande Anse Fm. Re‐evaluation of the palynological data delimits the Grande Anse Fm as Langsettian, providing a tight constraint of less than 2 myr on the timing of deformation. Diversion of palaeoflows by the rising salt structure, noted in previous work on the upper Boss Point Fm, occurs to the north of the diapiric anticline. This is interpreted to signify the development of a mini‐basin on commencement of diapirism once a ~1.5 km‐thick succession of clastic strata had buried the salt. Faults and folds in the succession below the unconformity indicate an initial phase of dextral transpressive strike‐slip motion, which may have promoted halokinesis. Reverse faults indicate shortening associated with northward development and overturn of the Minudie Anticline during transpression; subsequent normal faulting was associated with collapse of the sediment pile and underlying salt structure.