Kingak Shale and similar units

Unit symbol: KJks
Age range Lower Cretaceous to Lower Jurassic (201.3 to 129.4 Ma)
Lithology: Sedimentary
Group name: Kingak Shale, Shublik Formation, and Karen Creek Sandstone, undivided
Dark-gray to dark-olive-gray shale and subordinate siltstone, claystone, and clay ironstone (Detterman and others, 1975). Upper part is clay shale, silty shale, and siltstone that have red, rusty-weathering ironstone beds. Lower part is dark-gray to black fissile paper shale, dark-gray clay shale, minor claystone, and beds and nodules of red-weathering ironstone (Reiser and others, 1980). Molenaar (1983) extended the age range of the unit from its originally defined Jurassic age (Detterman and others, 1975) to Early Cretaceous on the basis of rocks assigned to this unit exposed south of the Sadlerochit Mountains, which Detterman and others (1975) had assigned to the Kongakut Formation. As mapped here, includes the Ipewik Formation of the De Long Mountains area (Moore and others, 1986; Curtis and others, 1990; Ellersieck and others, 1990; Mayfield and others, 1990), a significant component of which is either the same as or equivalent to the Kingak Shale. Ipewik Formation consists of maroon and gray shale, coquinoid limestone, siltstone, and clean quartz sandstone. Shale locally contains sparse well-rounded pebbles that consist of quartz, chert, gabbro, and granite and contains local light-weathering clay beds (bentonite?) and volcanic rocks of intermediate composition. The Telavirak and the underlying Ogotoruk Formations of the Point Hope quadrangle are also included here. The Telavirak Formation (Campbell, 1967) consists of rhythmically interbedded mudstone and siltstone or very fine- to medium-grained sandstone in nearly equal proportions. The Ogotoruk Formation is similar; it consists of chiefly dark-gray mudstone interbedded with variable amounts of siltstone and very fine- to medium-grained, dark-gray and brown sandstone. Rocks are generally classified as arkosic or feldspathic wackes

Source map information

Source map Keller, A.S., Morris, R.H., and Detterman, R.L., 1961, Geology of the Shaviovik and Sagavanirktok Rivers region, Alaska, in Exploration of Naval Petroleum Reserve No. 4 and adjacent areas, northern Alaska, 1944-1953, Part 3, Areal Geology: U.S. Geological Survey Professional Paper 303-D, p. 169-222, 6 plates, scale 1:63,360.
Symbol KJok
Unit name Okpikruak Formation and Kingak Shale
Description Kingak Shale crops out along the front of the mountain range between the Canning River and the Lupine River in a belt ranging from 3 to 10 miles in width; infolded with Permian and Triassic rocks within the mountains near the Kavik River. The formation overlies the Shublik Formation with no apparent angularity; it underlies Cretaceous Okpikruak formation disconformably, and locally unconformably underlies Cretaceous Ignek formation. Locally, rubble traces of ironstone and shale are present on the hillsides in the interstream areas, but these shale exposures are so spotty that they are of little help in defining the unit. Over much of the area it is difficult to differentiate the rocks of the Kingak from those of the Okpikruak formation. From the Canning River to Kemik Creek the Kingak predominantly consists of black pyretic clay shale and shaly siltstone which is locally iron stained and the clay shale is coated with white salt. Black dense siliceous locally fossiliferous siltstone and rust-weathering ironstone are present as beds and lenses in the shale
Lithology Sedimentary

Correlated geologic units

Label KJsh
Description Pebble shale and Kingak Shale, undivided
Geologic age Jurassic to Barremian
Geologic setting Sedimentary, deltaic-and-nearshore
Lithology Form Importance
Shale < Mudstone < Clastic < Sedimentary Bed Major