Upper Devonian and Lower Mississippian stratigraphy of Northwestern Montana: a petroleum system approach
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The Upper Devonian and Lower Mississippian stratigraphy in the Antler foreland basin of northwestern Montana is the current focus of exploration for several petroleum companies. Conodont zonation indicates that the Exshaw Formation of southern Alberta and northern Montana is Late Devonian and Early Mississippian in age, and is stratigraphically equivalent to the Bakken Formation in the Williston Basin and the Sappington Member of the Three Forks in southwestern Montana. The Exshaw, Bakken and Sappington are lithologically similar. Each formation is comprised of basal organic-rich shale, middle ...