Seabee Formation and Hue Shale

Unit symbol: Ksbf
Age range Upper Cretaceous, Coniacian to Turonian (93.9 to 86.3 Ma)
Lithology: Sedimentary
Group name: Seabee Formation and Hue Shale
Bentonitic mudstone, silty mudstone, and medium- to dark-gray to black, fissile, organic-rich shale containing interbedded bentonite and some thin, silicified tuff beds. Some localities characterized by large, yellowish-brown-weathering ovoid concretions greater than 3 ft (90 cm) in diameter. Unit consists only of rocks formerly mapped as Shale Wall Member of the Seabee Formation by Detterman and others (1963); other members have been abandoned. Unit defined by Gryc and others (1951) and Whittington (1956) and revised by Mull and others (2003). Map unit here also includes Hue Shale of Molenaar and others (1987), which consists of dark-gray, bentonitic shale in which fine-grained pyroclastic rock fragments weather yellow and greenish gray, and, in areas surrounding Sadlerochit Mountains, bright red. As mapped in Ignek Valley, includes some interbedded turbiditic shale and sandstone assigned to the Canning Formation. Interpreted by Molenaar and others (1987) to be a distal marine deposit and a condensed section; its upper parts may be equivalent in part with the lower part of the Canning Formation. The rocks of now-abandoned Ignek Formation are also included here; it consisted of a lower member of siltstone, shale, and locally fossiliferous subgraywacke sandstone; and an upper member, predominantly shale and lesser sandstone and siltstone beds, characterized by abundant pyroclastic deposits (Keller and others, 1961)

Source map information

Source map Mull, C.G., Houseknecht, D.W., Pessel, G.H., and Garrity, C.P., 2004, Geologic map of the Umiat quadrangle, Alaska: U.S. Geological Survey Scientific Investigations Map 2817-A, scale 1:250,000. []
Symbol Ks
Unit name Seabee Formation (Colville Group)
Description Bentonitic mudstone, silty mudstone, and medium to dark gray to black fissile, organic-rich shale, with interbedded bentonite and some thin silicified tuff beds; some localities characterized by large, yellowish brown-weathering ovoid concretions >1 m diameter; unit generally poorly exposed, forms broad tundra-covered valleys marked by scattered bare white-weathering shale frost boils. Best exposed at Shale Wall Bluff on Nanushuk River and in scattered stream cut exposures along the Chandler, Nanushuk, and Colville Rivers. Includes rocks formerly mapped as Shale Wall Member (Detterman and others, 1963). Unit defined by: (Gryc and others, 1951, Whittington, 1956, revised by Mull and others, 2004)
Lithology Sedimentary

Correlated geologic units

Label Ksbf
Description Seabee Formation (now only former Shale Wall Member)
Geologic age Cenomanian to Coniacian
Geologic setting Sedimentary, deltaic-and-nearshore
Lithology Form Importance
Shale < Mudstone < Clastic < Sedimentary Carbonaceous Major
Bentonite < Claystone < Mudstone < Clastic < Sedimentary Bed Indeterminate, major