Geology topics
Research about northern Alaska
Source-linked reports with geographic coverage including northern Alaska.
The Kingak shale of northern Alaska—regional variations in organic geochemical properties and petroleum source rock quality
The Kingak Shale, a thick widespread rock unit in northern Alaska that ranges in age from Early Jurassic through Early Cretaceous, has adequate to good oil source rock potential. This lenticular-shaped rock unit is as much as 1200 m thick near the Jurassic shelf edge, where its present-day burial depth is about 5000 m. Kingak sediment, transported in a southerly direction, was deposited on the then marine continental shelf. The rock unit is predominantly dark gray Shale with some interbeds of thick sandstone and siltstone. The thermal maturity of organic matter in the Kingak Shale ranges from immature (<0.6% R 0 ) on the Barrow arch to postmature (>2.0% R 0 ) in the Colville basin toward the south. Its organic carbon and hydrogen contents are highest in the eastern part of northern Alaska south of and around the Kuparuk and Prudhoe Bay oil fields. Carbon isotope data of oils and rock extracts indicate that the Kingak Shale is a source of some North Slope oil, but is probably not the major source.
Phosphate deposits in northern Alaska
Deposits of low and medium grade phosphate rock were found recently at seven localities on the Arctic slope of Alaska. They were reported by field parties of the U.S. Geological Survey during the mapping of Naval Petroleum Reserve No. 4 and adjacent areas. The deposits are sedimentary in origin and are confined to a thin zone in the Lisburne group of Mississippian age. Six of the localities are in a narrow belt along the north front of the Brooks gang between the Anaktuvuk and Okokmilaga rivers. The seventh is near the Ipnavik River about 100 miles northwest of the Okokmilaga River. At all but two of these localities the zone of soft phosphatic rocks does not crop out extensively and samples of phosphate rock were collected chiefly from float or talus. Little or nothing is known about the thickness and extent of the deposits. Near Chandler Lake on the upper Kiruktagiak River and 11 miles west of at the head of Tiglukpuk Creek, the phosphatic zone is well-exposed. This paper is a preliminary report on the results of a detailed examination of the phosphatic zone in these two areas during the summer of 1953.