ABSTRACT

Dissolution of the Middle Devonian Prairie Evaporite is a major structure-forming process in the south-central Saskatchewan segment of the Williston Basin. Dissolution occurred as a multistage process of salt removal which included eventual collapse of the overlying sedimentary column and accelerated sedimentation into surface depressions produced during collapse. The dissolution process began soon after deposition of the Middle Devonian salts and has continued to the present. Salt removal of late Mesozoic and Cenozoic age, interpreted from post-Second White Speckled Shale (Upper Cretaceous) dissolution trends, is apparent at several locales in the area of investigation (Saskatchewan Twp. 1-17, Rge. 15-30 W2M; Montana Twp. 36N-37N, Rge. 44E-58E; North Dakota Twp. 162N-164N, Rge. 102W-103W). The late-stage solution collapse features, coupled with the erosional effects of Pleistocene glaciation, played a significant role in producing the current outcrop distribution in south-central Saskatchewan.