Colville Foreland Basin and Arctic Alaska Prograded Margin Tectono-Sedimentary Elements, northern Alaska and southwestern Canada Basin

Abstract

Cretaceous (post-Neocomian)–Quaternary Brookian strata of Arctic Alaska include the Colville Foreland Basin (CFB) and Arctic Alaska Prograded Margin (AAPM) Tectono-Sedimentary Elements (TSEs). The CFB TSE lies beneath the Alaska North Slope and Chukchi Sea shelf, and the AAPM TSE lies beneath the Arctic Alaska continental terrace of the Beaufort Sea shelf and slope. The CFB TSE rests on rocks ranging from pre-Mississippian sedimentary and metasedimentary rocks (Franklinian sequence) to Lower Cretaceous strata, and is present at the land surface onshore and the seafloor offshore. The AAPM TSE generally rests on Lower Cretaceous (Neocomian) sedimentary strata and is present at the seafloor. The CFB and AAPM TSEs contain oil-prone source rocks in Cretaceous and Paleogene strata, and have been charged locally by hydrocarbon migration from pre-Brookian strata. Both TSEs contain proven reservoir rocks throughout the succession. The CFB TSE ranges from oil-window to gas-window maturity. The AAPM TSE is mainly in the gas window. Known hydrocarbon accumulations in the two TSEs total more than 3.4 Bbbl of oil equivalent and yet-to-find estimates suggest an even larger volume remains undiscovered. Current exploration is focused on shallow stratigraphic traps, in which giant oil accumulations have been discovered in recent years.