Canning Formation

Unit symbol: TKcf
Age range lower Tertiary, Oligocene? to Cretaceous, Albian (83.6 to 56 Ma)
Lithology: Sedimentary
Group name: Canning Formation
Consists of gray shale and siltstone containing interbeds of mostly thin-bedded, very fine- to fine-grained lithic sandstone. Unit informally divided in two facies: a turbidite sandstone facies and a slope-and-shelf facies. Turbidite facies are present throughout age range and areal distribution of unit; slope and shelf facies apparently entirely Tertiary in age and present only in eastern part of unit (Bird and Molenaar, 1987). Unit is 1,500 to 1,800 m thick in wells west of the Canning River and thinner to the east (Bird and Molenaar, 1987). Unit becomes younger from west to east: at Canning River it is entirely Cretaceous, in easternmost exposures, unit is Eocene and possibly as young as Oligocene in the subsurface. Lateral equivalent, in part, of the Sagavanirktok (unit Tsf) and Prince Creek Formations (unit TKpc). Unit is a time-transgressive turbiditic sandstone and shale as described by Molenaar and others (1987) and is recognized on the surface only in northeastern Alaska. In the subsurface west of the Canning River, unit may be equivalent to the Torok Formation (unit Kto, here; Molenaar and others, 1987). To the east and offshore, Houseknecht and Schenk (1999) suggest the Canning Formation may become as young as Miocene

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 Kc
Description The Canning Formation, although dominantly fine grained, consists of a wide range of lithologies including bentonite, tuff, shale, siltstone, lime mudstone, tuffaceous and lithic sandstones, and local conglomerate. The following description draws heavily from exposures along Sagashak Creek, where discontinuous outcrops offer the most complete view into the range of facies and their stratigraphic order (LePain and others, 2008a, 2008b). At Sagashak Creek, the base of the formation is complexly deformed by a more-than-20-m-thick (66-ft-thick) zone of disharmonic folds bounded above and below by undisturbed strata—a condition common in mass transport slump complexes. Regional well and seismic data provide evidence of potentially correlative mass wasting associated with a mid-Campanian unconformity (MCu; Decker, 2007), which in some areas represents the base of the Canning Formation. The lower part of the formation includes dark-gray-weathering, organic-rich clay shale and fissile to chippy siltstone interbedded with thin, brown- to light-gray-weathering, plane-parallel laminated, very fine sandstone beds. Rippled, orange-weathering tuffaceous sandstone and siltstone beds with local small, soft-sediment slump folds are associated with whitish-yellow bentonite seams and laminated gray- and reddish-brown-weathering silicified tuffs—the latter are locally strongly oil stained near the very base of the formation. Thin lime mudstone beds up to 30 cm (12 in) thick are present but rare. The significant contribution of air-fall volcanic material in this lower part of the formation imparts a conspicuous reddish-orange-weathering hue visible from a distance. The middle part of the formation, where exposed, includes interbeds of thin- to thick-bedded, tan-to-buff-weathering carbonaceous sandstone, light gray siltstone, and several poorly sorted pebble to cobble conglomerate beds up to 50 cm (20 in) thick. Thin- to medium-bedded sandstones exhibit subtle normal grading with abundant and diverse sole marks including loads, flutes, and grooves; bedding ranges from internally massive to plane laminated and rippled; carbonaceous particles and larger fragments are common on bedding planes. The conglomerate beds have up to 20 cm (8 in) of relief on scoured bases and include both intra- and extra-basinal clasts up to small cobbles; clast types include varieties of chert and siliceous mudstone, white vein quartz, tuff, shale, and orange-weathering sideritized (?) mudstone rip-ups. The upper part of the formation along Sagashak Creek includes a remarkably repetitive series of centimeter-scale beds of very-fine-grained, normally graded to plane-parallellaminated sandstone and siltstone; beds are laterally continuous and of uniform thickness, giving the outcrops a monotonous appearance. The uppermost part of the formation is more variable where exposed farther north on an unnamed creek near the hinge of the Kuparuk anticline, and includes bentonite and several thin conglomerate beds. A noteworthy but isolated conglomeratic outcrop in the southern part of the map is also tentatively assigned to the Canning Formation primarily based on clast composition, but its stratigraphic position in the unit is not known. This reddish-weathering knob is east of the Sagavanirktok River, in the immediate footwall of Ice Cut thrust. Approximately 10 m (4 ft) thick, the weakly stratified pebble conglomerate is poorly sorted, mostly clast supported, and includes lenticular interbeds of sandstone up to 50 cm (20 ft) thick; clasts are well rounded, up to 15 cm and include about 15 percent vein quartz, abundant chert and siliceous mudstone, and lesser fine-grained quartzite. The remainder of sedimentary facies observed in the map area are consistent with base-of-slope to slope settings dominated by sediment gravity flows ranging from unconfined dilute turbidity currents to higher density flows; the conglomerate beds may reflect submarine channel incision and filling. These interpreted depositional processes and settings are consistent with regional well and seismic correlations indicating that in this map area the Canning Formation represents deepwater clinoform deposits equivalent to the nonmarine and shallow-marine topsets of the Prince Creek and Schrader Bluff Formations (LePain and others, 2008a). The outcrops in the map area represent the westernmost (and oldest) examples of the Canning Formation exposed at the surface. The only megafossil known from this unit in the map area is the late Santonian to earliest Campanian bivalve Sphenoceramus patootensis (Mull, unpublished data) collected from the lower part of the formation on Sagashak Creek. Palynologic data support a Campanian age for most of the formation in this area (DGGS, unpublished data). LePain and others (2008b) calculated a thickness of approximately 1,300 m (4,265 ft) at Sagashak Creek, where direct measurement is complicated by long stretches of cover; the unit has a vertical thickness of 1,166 m (3,825 ft) in the Echooka Unit 1 well approximately 30 km (18.6 mi) to the north, where it represents the measured depth interval 2,312–3,478 m (7,585–11,411 ft) (fig. 4).
Lithology Sedimentary

Correlated geologic units

Label TKcf
Description Canning Formation, basinal turbidite deposits
Geologic age Campanian to Paleocene
Geologic setting Sedimentary, slope-and-deep-water
Lithology Form Importance
Shale < Mudstone < Clastic < Sedimentary Bed Major
Siltstone < Clastic < Sedimentary Bed Major