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 Gillis, R.J., Decker, P.L., Wartes, M.A., Loveland, A.M., and Hubbard, T.D., 2014, Geologic map of the south-central Sagavanirktok Quadrangle, North Slope, Alaska: Alaska Division of Geological & Geophysical Surveys Report of Investigation 2014-4, 24 p., 2 sheets, scale 1:63,360. doi:10.14509/29138
Symbol Ks
Description Strata assigned to the Seabee Formation in the map area are organized into packages dominated by either sandstone or mudstone. Sandstone is typically light gray to locally rusty-red–brown weathering, very fine to fine grained, and moderately indurated to slightly friable; weak to moderate oil odor is observed in the more friable examples. Mica and/or phyllitic rock fragments are locally abundant and readily apparent to the unaided eye. Sandstone beds are commonly internally massive with cryptic amalgamation surfaces that pass laterally into mudstone, indicating local scouring. Sedimentary structures locally include normal grading, plane-parallel lamination, parting lineation, flutes, grooves, ripples, and small-scale trough cross-stratification. Rip-up clasts of mudstone are concentrated in some beds. The best exposures of the sandstone packages are found discontinuously along Sagashak Creek near the core of the Aufeis anticline (LePain and others, 2008) and just downstream of the confluence of the Lupine and Sagavanirktok rivers. Uplands in the southeastern part of the map area, such as the prominent hilltop occupied by VABM Inter, exhibit rubble traces of resistant sandstone, consistent with the discrete sandstone/mudstone packaging recognized in better exposures along rivers and streams. Mudstone-dominated packages are rarely exposed and are inferred to underlie many covered intervals between resistant sandstone bodies; where observed, they consist of medium gray argillaceous siltstone, olive-gray chippy siltstone, and lesser green-gray fissile clay shale. An excellent exposure along the Lupine River approximately 1.6 km (1 mi) downstream of the trace of the Ice Cut thrust includes both a lower, mudstone-dominated interval and an upper, sandstone dominated interval; in the fine-grained facies, platy-weathering siltstone is finely intercalated with densely rippled, thin beds of very-fine sandstone and, rarely, thin bentonite seams; sandstone abundance and bed thickness increase dramatically above a scoured surface with ~2 m) ~6.5 ft of erosional relief. Granule and pebble conglomerate was observed at one locality along the west bank of the Sagavanirktok River, about 1.6 km (1 mi) north of the Ice Cut thrust; clasts include abundant white tripolitic chert in addition to brown, gray, and black fresh chert and silicified mudstone. Based principally on the sedimentary structures in the sandstone, the Seabee Formation is interpreted as dominantly sediment gravity flow deposits; local evidence for tractive sediment transport and scouring suggest deposition via turbulent flows. A deep water setting is suggested by the lack of bioturbation and supported by regional subsurface interpretations that indicate the map area lies basinward of the Turonian shelf edge (Houseknecht and Schenk, 2005). The deepwater depositional setting and facies in the map area contrast with those of the Seabee Formation described in previous outcrop studies to the west where the unit was deposited in shallower water on the shelf constructed by the underlying Nanushuk Formation (see summary in Mull and others, 2003). The deepwater Seabee Formation of the map area may more closely resemble the Cenomanian to Turonian interval drilled in the Tarn–Meltwater area to the northwest. However, the locally abundant and conspicuous mica flakes and phyllitic(?) rock fragments appear unique to the eastern foothills; this is one of several factors that suggests the unit in the map area had more direct and persistent input from provenance areas in the ancestral Brooks Range than correlative Seabee intervals farther northwest. Age control in the map area is provided by the early Turonian bivalve Mytiloides labiatus (Mull, unpublished data) and the uppermost Cenomanian to early Turonian ammonite Scaphites delicatulus Warren (W. Elder, written communication, 2008). The complete thickness of the Seabee Formation is not adequately constrained from outcrop data; the Echooka Unit 1 well penetrated a vertical thickness of 315 m (1,033 ft) in the measured depth interval 3,265–3,580 m (10,713–11,745 ft) (fig. 4).
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