Evaporite karst in the Black Hills, South Dakota and Wyoming, and the oil play in the Williston Basin, North Dakota and Montana NCKRI Symposium 2: Proceedings of the Thirteenth Multidisciplinary Conference on Sinkholes and the Engineering and Environmental Impacts of Karst

pg(s) 161-175 Subsurface red beds of the Permo-Triassic age Spearfish Formation in the Williston Basin has recently been touted as another Bakken Oil Boom for North Dakota . The senior author, totally uninformed about the subsurface geology of North Dakota, was requested by INFOCAST* to discuss petroleum potential in the Spearfish based on his field experience in the outcrop belt of the Black Hills in neighboring Wyoming and South Dakota. That request was extended to a discussion of the surface and subsurface evaporite-karst features in four formations ranging from Pennsylvanian to Jurassic age. Dissolution of these rocks, which has resulted in sinkholes, caves, springs, breccia pipes, and subsurface collapse, has apparently gone on since the Black Hills was formed during the Early Tertiary, and continues today. The formation of salt-dissolution paleokarst in the Williston Basin and adjacent Powder River Basin has been documented to have occurred many times in the geologic past, between the mid-Paleozoic through the Tertiary. Reported subsurface collapse has affected rock characteristics, including local structure, fracturing, porosity, and permeability. These significant effects of evaporite karst in the Williston Basin, as well as in subsurface evaporite-bearing sequences nationally, should be of concern to any oil exploration efforts, as well as for surface infrastructure development such as pipeline right-of-way. Open Access - Permission by Publisher See Extended description for more information