Summary

Numerous models have been proposed for the formation of the Canada Basin ranging from early submersion models to generalized counter-clockwise rotation and southward translation strike-slip models. This study correlated biostratigraphic tops and foraminiferal biofacies/paleoenvironments for 69 key North Slope, Alaska wells and 59 Sverdrup Basin, Canada onshore and offshore wells. Reconstruction of the pre-rift configuration of the Sverdrup and North Slope regions was interpreted for 39 time periods in the Paleozoic and Mesozoic. Timing of rifting and spreading was interpreted from sediment ages and facies in smaller grabens along the Barrow Arch. Analysis of these data can be interpreted to support a propagating-rift model that resulted in the apparent counterclockwise “rotation” of Siberia and northern Alaska away from the Canadian Arctic Islands. This model involves incipient rifting in the late Rhaetian, forming a chain of half grabens extending from the Lomonosov Ridge to the Mackenzie Delta. Subsequently, active spreading began at the Lomonosov Ridge (reconstructed position) in early Aalenian time and propagated southward at a rate of 2.3 cm/yr ending at the Mackenzie Delta by mid-Cenomanian time. Spreading rates are estimated to be approximately 2.4 cm/yr in the northern portion of the rift system and 3.1 cm/yr in the southern portion. This model accounts for the major physiographic and geologic features evident for the Canada Basin and margins including: the Lomonosov and Mendeleev and Alpha ridges and Northwind Escarpment; the variable width of the Canada basin from the Lomonosov Ridge to the Mackenzie Delta; the age distribution of sediments in the Colville Trough and Early Cretaceous age grabens along the Barrow Arch; the nature of Brooks Range orogeny and palinspastic reconstruction of minimum estimates of crustal shortening as evidenced by thrusting relationships in the western Brooks Range; the ages assigned to the time of spreading reported in the literature at various locations along the rift axis; and the age of faulting relationships for the North Slope, Sverdrup Basin and the Mackenzie Delta regions.