ABSTRACT

Seven impact structures are now known from the Western Sedimentary Basin of North America. This contribution reports on the discovery of shock metamorphic effects at three of these structures: Elbow, Maple Creek and Viewfield, all in Saskatchewan. It also describes their general character and that of the other impact structures in the basin. Particular emphasis is placed on the production of hydrocarbons from these structures, which ranges from none to 1000 BOPD (at Red Wing Creek, North Dakota). Other hydrocarbon-producing impact structures in Canada, Mexico and the United States are briefly characterized along with their productivity. Most production at impact structures occurs from structural traps in the rim and central uplift and from brecciated target rocks, including crystalline rocks. The most productive impact-related hydrocarbon reservoir rocks are breccias in the Gulf of Mexico believed to be genetically linked to the K/T impact that formed the Chicxulub structure on the Yucatan Peninsula, Mexico. Many impact structures remain to be discovered throughout the world. For example, the current estimate of the terrestrial cratering rate indicates that as many as 12 + 6 impact structures with diameters of 10 km or greater remain to be discovered in the Williston Basin. If half of them have reserves similar to the 9 km diameter Red Wing Creek structure, the cumulative potential impact-related reserves are in the order of 1 BBO and 600 BCFG in the Williston Basin alone.