Kanayut Conglomerate and Noatak Sandstone, undivided

Unit symbol: MDegk
Age range Lower Mississippian and Upper Devonian (382.7 to 346.7 Ma)
Lithology: Sedimentary
Group name: Kanayut Conglomerate and Noatak Sandstone, undivided (Endicott Group)
Kanayut Conglomerate is one of the most widely exposed units of the Endicott Group. Nilsen and Moore (1984) locally divided it into three formal members (in ascending order): the Ear Peak, Shainin Lake, and Stuver Members. It is also commonly mapped as an undivided unit with the Noatak Sandstone. Kanayut Conglomerate has been mapped across the breadth of the Brooks Range, from the east end, by Brosgé and others (1962), to the westernmost Brooks Range, by Nilsen and Moore (1984). Where Kanayut Conglomerate and Noatak Sandstone are mapped undivided, the lower marine part of section corresponds to the Noatak Sandstone and upper parts of section represent the Kanayut Conglomerate. The lowermost member, the Ear Peak, is a sequence of fining-upward fluvial cycles of conglomerate, sandstone, and shale as thick as 1,160 m, deposited by meandering streams. The Shainin Lake Member is a sequence of fining-upward couplets of conglomerate and sandstone as thick as 530 m, deposited by braided streams. The Stuver Member is a sequence of fining-upward fluvial cycles of conglomerate, sandstone, and shale as thick as 1,300 m, deposited by meandering streams. Mull and others (1987b) suggest that the proportion of conglomerate decreases southward in the Kanayut Conglomerate. Metamorphic grade increases towards the metamorphic core of the Brooks Range (Central Belt of Till and others, 2008a). Age control based on plant fossils, largely of Late Devonian age, but including Early Mississippian plants. Noatak Sandstone described below where it is mapped separately

Source map information

Source map Kelley, J.S., 1990, Generalized geologic map of the Chandler Lake quadrangle, north-central Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-2144-A, 19 p., 1 sheet, scale 1:250,000.
Symbol Dkln
Unit name Kanayut Conglomerate and Noatak sandstone, undivided
Description Ear Peak Member of Kanayut Conglomerate and Noatak Sandstone. Ear Peak Member is mostly shale, mudstone, sandstone, and conglomerate. Shale is reddish brown, grayish-green, brownish-gray, and grayish-black, very silty, micaceous and grades to siltstone. Sandstone is quartz-rich and ranges between orthoquartzite and quartz-rich with varying cements. Conglomerate is largely granule- to cobble-sized quartz and chert having a sandstone matrix. Unit varies across map area; sandstone most abundant in north and east, shale south of Toyuk mountain Thrust. Noatak Sandstone is principally sandstone and mudstone. Pinkish-gray, light-brownish-gray, and light light-gray calcareous-cemented, fine- to coarse-grained sandstone is typical. Locally sandstone is deeply iron-stained, providing possible evidence of nonmarine sedimentation.
Lithology Sedimentary

Correlated geologic units

Label MDkn
Description Endicott Group, Kanayut conglomerate and Noatak sandstone
Geologic age Frasnian to Visean
Geologic setting Sedimentary, continental
Lithology Form Importance
Conglomerate < Clastic < Sedimentary Bed Major
Shale < Mudstone < Clastic < Sedimentary Bed Major
Sandstone < Clastic < Sedimentary Bed Indeterminate, major