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 Brosge', W.P., Reiser, H.N., Dutro, J.T., Jr., and Detterman, R.L., 1979, Bedrock geologic map of the Phillip Smith Mountains quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-879-B, 2 sheets, scale 1:250,000.
Symbol Jk
Unit name Kingak Shale
Description Dark gray, gun-metal blue weathering; hard siltstone with shale interbeds; abundant nodules of clay ironstone and marcasite. Southwest of Ribdon River consists only of a local unit of black organic clay shale that is too thin to map. This unit is included in undivided Jurassic and Cretaceous rocks (KJok) on Atigun River, but may also be present in some poorly exposed areas mapped either as Kongakut or Okpikruak Formations. Marine. Middle and Late Jurassic ammonites and pelecypods in northeastern part of unit; Early Jurassic pelecypods in southwest. Thickness about 370m in northwest; 30 m or less in southwestern part of unit.
Lithology Sedimentary

Correlated geologic units

Label KJks
Description Kingak Shale
Geologic age Jurassic to Hauterivian
Geologic setting Sedimentary, deltaic-and-nearshore
Lithology Form Importance
Shale < Mudstone < Clastic < Sedimentary Bed Major
Claystone < Mudstone < Clastic < Sedimentary Bed Indeterminate, major
Siltstone < Clastic < Sedimentary Bed Minor