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n Alas - Alaska Division of Geological & Geophysical Surveys - State ... n Alas - Alaska Division of Geological & Geophysical Surveys - State ...

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a lower black or gray fissile shale end an upper thin- bedded fine-grained sandstone with abundant ripple markings and burrows. Black or gray siltstone, with some intercalated thin-bedded sandstone and carbon- ate turbidites, forms the upper part of the Kayak. Tfre Kayak records a marine transgression over the domi- nantly fluvial Kanayut delta and gradually deepening conditfons. The Kanayut Conglomerate is distinguishable horn other units of the Endicott Group in the "Husky MountaInsn and the Mulgrave Hills by: (1) fiming- upward cycles of conglomerate, sandstone, and shale; (2) the presence of red or brown shale intervals that B Grain size rcm, 5 .2 MSS sh &hale cement Fault I corn monly contain brigh tIy colored oxidized paleosols; (3) highly indurated silica-cemented sandstone and conglomerate; and (4) erosional truncation of shale and pdeosol Intervals by overlying channeled conglomerate and sandstone. The minimum thickness of the Kanayut that we have measured in the western Brooks Range is 240 m. However, we have not identified the various members of the Kanayut in this area. Substantiation of the presence of Kanayut Con- glomerate lithofacies in the westenmost Brooks Range broadens our understanding of: (1) lhe lateral extent of the large mid-Paleozoic and dominantly fluvial delta on which the Kanayut was deposited Grain slze (no scale) , ~~+ERs , , , , METERS C mi Sandstone Ri Trough cross-stam Tabular cross.straia m Sane-wave strata Parallel strata -&+ Ripple marks ~areosoi A Bunow 0 wan! fossil a Musk lossll -4 Root cast / Flnlng-upward cycle Pigwe 7.-Stratigraphic sections of the Kanayut Measured section showing composite fluvial and Conglomerate in "Husky Mountainsn and Mulgrave marine cycIes in the Kanayut Conglomerate. Grain- Hills, western Brmks Range, Alaska (fig. 6). & size scale for sections shows increasing width From Schematic stratigraphic column of the Endicott shale (sh) to medium-grained sandstone (mss) to Group. 3 Measured section showing finfng-upward conglomerate with maximum clast sizes of 0.2 und 5 fluvial cycles in the Kanayut Conglomerate. ern.

I (Nilsen and others, 1981a); (2) facies changes within the delta; and (3) the companents of the stratigraphic sequence In this area. The Kanayut Conglomerate could possibly extend farther west. Although our fieldwork in 1982 suggests that coal-bearing Mississip- pian rocks on the Lisburne Peninsula, described by Tailleur (19651, are not equivalent to the Kanayut, Devonian red beds on W rangel Wand, which is located off the north coast of Siberia, may possibly be equiva- lent to the Kanayut Conglomerate (Bogdanov and Ttlman, 1964). The ' present known thickness and lateral extent of the Kanayut Conglomerate indicates that it is one of the most signlflcant fluvial deposits in North America and that it records major uplift and orcgeny in the Brooks Range area. In the westernmost Brooks Range, it Is clearly thinner (several hundred meters to 3,000 m), finer gralned (maximum cl&t size, 1-3 to 23 cm), conteins more intercalated marine strata in its lower part, and is less eesily divisible or not divisible into its three members. However, it js clearIy present in an Upper Devonian and Lower Mls- sissippian stratigraphic sequence that, to us, is re- .narkably similar to that of the central and eastern kooks Range, rather than markedly different, as some lrevious workers had reported. REFERENCES ClTBD Bogdanof, N. A., and Tilrnan, S. M., 1964, Obshchie cherty randliia paleazokkikh struktur ostrova vrangella 1 zabadnof chasti khrebta Bruksa (AUaska) [Similarities in the development of the Paleozoic structure of Wrangel Island and the western part of the Brooks w e (~laska)l, & Soveshchanie po problem tektoniki: Skadchatye Oblasti Evrezii, Materialy, Moskva, Nauka, p. 219-230. Bowsher, A. L., end Dutro, J. T., Jr., 1957, The Paleozoic section in the Shahin Lake area, central Brooks Range, Maskar U.S. Geological Survey Professional Paper 303-A, p. 1-39. Brosg-6, W. P., and Pessel, G. H., 1977, Preliminary reconnaissance geologic map of Survey Pass quadrangle, Alaska: U.S. Geological Survey Open-File Report 77-27, scale 1:250,000. Brosgk, W. P., Reiser, H. N., Dutro, J. T., Jr., and Detterrnon, R. L., 1979a, Bedrock geologic map of the Philip Smith Mountains quadrangle, Alaska: U.S. QeologicaZ Survey MisceUaneous Field Studies Map MF-879-B, soale Zr250,000, 2 sheets. Brcrsg6, W. P., Refser, H. N., Dutm, J. T., Jr., and Nilsen, T. H., 1979b, Geologlc map of DevonIan rocks in parts of the Chandler Lake and Klllik River quadrangles, Alaska: U.S. Geologlcd Survey Open-File Report 79-1224, scale 1:200,000. durtis, S. M., Ellersiwk, tnyo, Mayfield, C. F., and TaiUeur, I. L., 1982, Reconnaissance geologic map of southwestern Misheguk Mountain quadrangle, Alaska: U.S. Geoglcal Survey Open- FIle Report 82-611, scale 1:63,360. Dutro, J. T., Jr., 1953, Stratigraphy and paleontology of the Noatak and associated formations, Brooks Range, Alaska: New Haven, Conn., Yale University, Ph. D. thesis, 154 p. EUersleck, lnyo, Curtis, S. M., Mayfteld, C. F., and TaiUeur, I. L., 1882, Recomafssance geologic map of south-central Misheguk Mountain quadrangle, Alaska: U.S. Geological Survey Open- File Report 82-612, scale 1:63,380. Ellersieck, Inyo, Mayfield, C. P., Tallleur, I. L., ad Curtis, S. M., 1978, Thrust sequences in the Misheguk Mountain quadrangle, Brooks Range, Alaska, & Johnson, K. M., and Williams, J. R., eds., The United States Geological Survey In Alaska: Accomplishments during 1978: U.S. Geologlcal Survey Circular 804-B, p. 38-89. Gryc, George, Dutro, J. T., Jr., Brosg6.W. P., Taillear, I. L., and Churkin, Michael, Jr., 1967, Devonian of Alaska, 5 Oswald, D. H., ed., hternational Symposium on the Devonian System: Calgary, Alberta, Canada, Alberta Society of Petroleum Geologists, v. 1, p. 703-716. Mayfield, C. P., Curta, S. M., Bllersieck, Inyo, and TaiUeur, I. L., 1982, Reconnaissance geologic map of southeastern Mishaa;uk Mountain quadrangle, Alaska: U.S. Geological Survey Open- Pile Report 82-613, scale 1:63,350. Mayfield, C. P., and Tallleur, I. L., 1978, Bedrock geologic map of the Ambler River quadrangle, Alaska1 U.S. Geological Survey Open-Pile Report 78-120-A, scale 1:250,000. Mayfield, C. F., Tailleur, I. L., Mull, C. G., and Sable, E. Q., 1978, Bedrock geologic map of the south haLf of National Petroleum Reserve in Alaska: U.S. Geological Survey Open-File Report 78-70- B, scale 1:500,000, 2 sheets. NeMn, S. W., and Grybeak, Donald, 1980, Geologfc map of the Survey Pass quadrangle, Brooks Range, Alaska: U.S. Geological Sswey MisceUaneow Field Studies Map MP-1176-A, scale 1:250,000, 2 sheets. Nilsen, T. H., Brosgb, W. P., Du-, J. T., Jr., and Moore, T. E., 2981a, Depositional model for the fluvlal Upper Devonian Kanayut Conglomerate, Brooks Range, Alaska, Albert, N. R. D., and Hudson, Travis, eds, The United States Geological Survey In Alaska: Accomplishments during 1979: U.S. Geological Survey Circular 823-B, p. B2 0-B2l. Niben, T. H., and Moore, T. E., 1982, Sedimentology and stratigraphy of the Kanayut Conglomerate, central and western Brooks Range, Alaskareport of 1881 field season: U.S. Geological Survey Open-File Report 92-674, 64 p. Nilsen, T. H., Moore, T. E, Balin, D. P., and Johnson, S. Y., 1982, Sedimentology and stratigraphy of the Kmayut Conglomerate, central Brooks Range, Alaska--report of 1980 fleld seasonr U.S. Geologlcal Survey Open-Pile Report 02-199, 81 P. Nilsen, T. H., Moore, T. E., Brosgb,~. P., and Dutro, J. T., Jr., 198lb, Sedlmentolagy and stratigraphy of the Kanayut Conglomerate and associated units, Brwks Range, Alaska--report of 1981 field season: U.S. Geologiaal Survey Open-File Report 81-506, 39 p. Nilsen, T. H., Mmrc, T. E., Dutro, J. T., Jr., Brosgk,w. P., and Orchard, D. M., 1980, Sedimentology and stratigraphy of the Kanayut Conglomerate and associated units, central and eastern Brooks

a lower black or gray fissile shale end an upper thin-<br />

bedded fine-grained sandstone with abundant ripple<br />

markings and burrows. Black or gray siltstone, with<br />

some intercalated thin-bedded sandstone and carbon-<br />

ate turbidites, forms the upper part <strong>of</strong> the Kayak. Tfre<br />

Kayak records a marine transgression over the domi-<br />

nantly fluvial Kanayut delta and gradually deepening<br />

conditfons.<br />

The Kanayut Conglomerate is distinguishable<br />

horn other units <strong>of</strong> the Endicott Group in the "Husky<br />

MountaInsn and the Mulgrave Hills by: (1) fiming-<br />

upward cycles <strong>of</strong> conglomerate, sandstone, and shale;<br />

(2) the presence <strong>of</strong> red or brown shale intervals that<br />

B<br />

Grain size<br />

rcm,<br />

5 .2 MSS sh &hale<br />

cement<br />

Fault I<br />

corn monly contain brigh tIy colored oxidized paleosols;<br />

(3) highly indurated silica-cemented sandstone and<br />

conglomerate; and (4) erosional truncation <strong>of</strong> shale and<br />

pdeosol Intervals by overlying channeled conglomerate<br />

and sandstone. The minimum thickness <strong>of</strong> the Kanayut<br />

that we have measured in the western Brooks Range is<br />

240 m. However, we have not identified the various<br />

members <strong>of</strong> the Kanayut in this area.<br />

Substantiation <strong>of</strong> the presence <strong>of</strong> Kanayut Con-<br />

glomerate lith<strong>of</strong>acies in the westenmost Brooks<br />

Range broadens our understanding <strong>of</strong>: (1) lhe lateral<br />

extent <strong>of</strong> the large mid-Paleozoic and dominantly<br />

fluvial delta on which the Kanayut was deposited<br />

Grain slze<br />

(no scale) , ~~+ERs , , , , METERS<br />

C<br />

mi<br />

Sandstone<br />

Ri<br />

Trough cross-stam<br />

Tabular cross.straia<br />

m<br />

Sane-wave strata<br />

Parallel strata<br />

-&+<br />

Ripple marks<br />

~areosoi<br />

A<br />

Bunow<br />

0<br />

wan! fossil<br />

a<br />

Musk lossll<br />

-4<br />

Root cast<br />

/<br />

Flnlng-upward cycle<br />

Pigwe 7.-Stratigraphic sections <strong>of</strong> the Kanayut Measured section showing composite fluvial and<br />

Conglomerate in "Husky Mountainsn and Mulgrave marine cycIes in the Kanayut Conglomerate. Grain-<br />

Hills, western Brmks Range, <strong>Alas</strong>ka (fig. 6). & size scale for sections shows increasing width From<br />

Schematic stratigraphic column <strong>of</strong> the Endicott shale (sh) to medium-grained sandstone (mss) to<br />

Group. 3 Measured section showing finfng-upward conglomerate with maximum clast sizes <strong>of</strong> 0.2 und 5<br />

fluvial cycles in the Kanayut Conglomerate. ern.

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