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 Wartes, M.A., Wallace, W.K., Loveland, A.M., Gillis, R.J., Decker, P.L., Reifenstuhl, R.R., Delaney, P.R., LePain, D.L., and Carson, E.C., 2011, Geologic map of the Kavik River area, northeastern Brooks Range, Alaska: Alaska Division of Geological and Geophysical Surveys Report of Investigation 2011-3A, 14 p., 1 sheet, scale 1:63,360.
Symbol KJk
Unit name Beaufortian Megasequence - KINGAK FORMATION
Description Dark gray to black soft clay shale, locally fissile and containing abundant bedding-parallel, reddish-orange- to brown-weathering sideritic(?) concretions, and lesser thin very-fine-grained sandstone beds. Typically recessive and only exposed in small discontinuous stream cutbanks, most notably in the southern part of the map area, directly north of the mountain front; also exposed in structural low in southeast corner of map. Locally well exposed beneath the LCu and Kemik Sandstone along the Canning River; near the Kkt unit, uppermost Kingak displays a resistant subcrop weathering pattern reflecting an upward increase in sandstone. Interpreted as quiet-water shelf deposits, possibly grading upward into prodelta turbidites near the top. May be as thick as 350 m (Molenaar, 1983), although inferred structural thickening of this mechanically weak section limits accurate estimates; wells in the northern part of the map area suggest an average thickness closer to 200 m (Nelson and others, 1999), although this is a minimum due to the northward increase of erosion along the LCu (Bird, 1999). The Lower Cretaceous part of the formation is equivalent to the Miluveach Formation of subsurface usage (Carmen and Hardwick, 1983)
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