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 Bader, J.W., and Bird, K.J., 1986, Geologic map of the Demarcation Point, Mt. Michelson, Flaxman Island, and Barter Island quadrangles, northeastern Alaska: U.S. Geological Survey Miscellaneous Investigations Series, Map I-1791, 1 sheet, scale 1:250,000.
Symbol KJs
Unit name Shale
Description Dark-gray shale. Contains rounded, frosted quartz sand grains and rare chert and quartzite pebbles. Upper part is informal pebble shale unit, lower part is Kingak Shale, these two units are not easily distinguished when the Kemik Sandstone, which separates them, is missing. As much as 550 m thick. Marine deposits.
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