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

Abstract

Cretaceous (post-Neocomian) to 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 mainly is in the gas window. Known hydrocarbon accumulations in the two TSEs total more than 3.4 billion barrels 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.

Assessment of undiscovered oil and gas resources of the North Chukchi Basin, outer continental shelf of the Chukchi and East Siberian Seas, Arctic Ocean, 2023

“…The basin fill comprises mainly Cretaceous and Cenozoic strata of the Brookian sequence (Houseknecht, 2022). Pre-Cretaceous strata of both the Ellesmerian (Triassic and older) and Beaufortian (Jurassic to Early Cretaceous [Neocomian]) sequences are truncated by erosion along the southern basin margin, as evident in seismic data, and are absent because of nondeposition on the northwestern basin margin.…”

“…Ages of the Cretaceous and Cenozoic strata in the U.S. Chukchi Sea shelf range from Aptian to Coniacian and from Paleocene to Oligocene, respectively, and are based on biostratigraphy, geochronology, and thermochronology from exploration wells and seafloor cores (Sherwood and others, 2002;Craddock and Houseknecht, 2016;Houseknecht and others, 2016;Homza and Bergman, 2019;Houseknecht, 2022). Across the entire shelf, Cretaceous and Cenozoic strata are separated by the "Mid-Brookian unconformity" (MBU), which occurs at the Cretaceous-Paleogene boundary (Homza and Bergman, 2019;Connors and Houseknecht, 2022).…”

“…Petroleum source rocks in the basin are inferred to be present in Cretaceous to Paleogene strata comprising the Hauterivian informal pebble shale unit, Barremian to Turonian Hue Shale, and upper Paleocene to middle Eocene strata coeval to distal organic-rich strata present across much of the Arctic Ocean (Houseknecht, 2022). Pseudowells were generated at intersections of seismic lines across much of the basin.…”