Geology between the Yukon River and Coldfoot, east-central Alaska

AbstractRecurring glacial outburst floods from the Yukon-Tanana Upland are inferred from sediments exposed along the Yukon River near the mouth of Charley River in east-central Alaska. Deposits range from imbricate gravel and granules indicating flow locally extending up the Yukon valley, to more distal sediments consisting of at least 10 couplets of planar sands, granules, and climbing ripples with up-valley paleocurrent indicators overlain by massive silt. An interglacial organic silt, occurring within the sequence, indicates at least two flood events are associated with an earlier glaciation, and at least three flood events are associated with a later glaciation which postdates the organic silt. A minimum age for the floods is provided by a glass fission track age of 560,000 ± 80,000 yr on the GI tephra, which occurs 8 m above the flood beds. A maximum age of 780,000 yr for the floods is based on normal magnetic polarity of the sediments. These age constraints allow us to correlate the flood events to the early-middle Pleistocene. And further, the outburst floods indicate extensive glaciation of the Yukon-Tanana Upland during the early-middle Pleistocene, likely representing the most extensive Pleistocene glaciation of the area.

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Age of some Pleistocene interglacial beds and associated fossils in eastern Beringia defined by fission tracks in glass shards of Chester Bluff tephra

Quaternary Research ◽

10.1017/qua.2017.30 ◽

2017 ◽

Vol 88 (1) ◽

pp. 152-159 ◽

Cited By ~ 1

Author(s):

John A. Westgate ◽

Nicholas J.G. Pearce

Keyword(s):

Fission Track ◽

Yukon Territory ◽

East Central ◽

Oxygen Isotope Stage ◽

Yukon River ◽

Dating Method ◽

The Mean ◽

Loess Deposits ◽

The Rich

AbstractApplication of the glass fission-track dating method to Chester Bluff tephra (CBt), exposed in loess deposits at Chester Bluff along the Yukon River in east-central Alaska, has clarified the age of the immediately underlying fossiliferous interglacial bed. Surprise Creek tephra (SZt), at site CRH47 in the northern Old Crow basin of the Yukon Territory, is a correlative of CBt so that the new age information on CBt can also be applied to the interglacial sediments below SZt. Two independent age determinations were obtained on CBt, 243±28 ka and 249±26 ka, giving a weighted mean age and error of 246±19 ka. Therefore, the closely associated interglacial bed belongs to the early part of Marine Oxygen Isotope Stage (MIS) 7. The stratigraphy and paleoenvironmental setting of SZt show that deposition of the tephra occurred soon after interglacial conditions, when the climate became colder, probably between MIS 7.5 and 7.4, that is, slightly younger than the mean fission-track age, but within the 1σ uncertainty. This result tightly constrains the age of the rich mammalian faunal assemblage found at and just below SZt at the CRH47 site.

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Bedrock geology of the eastern Koyukuk Basin, central Brooks Range, and east-central Arctic Slope along the Dalton Highway, Yukon River to Prudhoe Bay, Alaska, Volume 2

10.14509/2875 ◽

1989 ◽

Cited By ~ 2

Keyword(s):

Brooks Range ◽

East Central ◽

Yukon River ◽

Bedrock Geology ◽

Prudhoe Bay

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Magnetic susceptibilities of crystalline rock samples, Yukon River-Porcupine River area, east-central Alaska

Open-File Report ◽

10.3133/ofr7155 ◽

1971 ◽

Author(s):

William Peters Brosge ◽

Arthur Conradi

Keyword(s):

Crystalline Rock ◽

East Central ◽

Magnetic Susceptibilities ◽

Rock Samples ◽

Yukon River

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Llandoverian (Early Silurian) radiolarians from the Road River Formation of east-central Alaska and the new family Haplotaeniatumidae

Journal of Paleontology ◽

10.1017/s0022336000057796 ◽

2002 ◽

Vol 76 (6) ◽

pp. 941-964 ◽

Cited By ~ 18

Author(s):

Mun-Zu Won ◽

Robert B. Blodgett ◽

V. Nestor

Keyword(s):

Canadian Arctic ◽

Diagnostic Feature ◽

East Central ◽

The Road ◽

Rock Fragments ◽

New Family ◽

Yukon River ◽

Siliceous Rock ◽

The Family ◽

Arctic Fauna

Well-preserved Early Silurian radiolarians were recovered from siliceous rock fragments contained in a limestone boulder from the Road River Formation, Yukon River area, east-central Alaska. The radiolarians represent five genera, one of which, Parasecuicollacta, is new, and 17 species, nine of which are new: Secuicollacta magnitesta, S. tatondukensis, S. parvitesta, S. alaskensis, Parasecuicollacta bipola, P. hexactina, P. multispinosa, P. nannoglobosa, and Diparvapila pygmaea. Among the 17 species, 11 belong to the family Rotasphaeridae. The ectopically placed spicule, which is the diagnostic characteristic of the subfamily Secuicollactiniinae within the family Haplentactiniidae, is shown to be one of the primary units, a diagnostic feature of the family Rotasphaeridae. Three species are assigned to the family Haplotaeniatumidae, which is newly established in this paper. The family is characterized by the concentric and spiral arrangement of shell with a proloculus and commonly the presence of a pylome, and by the absence of an internal spicule. Several other taxa are extremely rare and are of uncertain taxonomic position. This fauna is characterized by very plentiful rotasphaerids, whereas all the other radiolarian taxa are very rare.The Road River fauna is similar to that from the Cherry Spring Chert of Nevada, thought to be late Rhuddanian based on a sparse graptolite fauna, and is very similar to an unreported Early Silurian Canadian Arctic fauna, whose stratigraphic range based on the graptolite fauna is within the early Telychian. Conodonts, chitinozoans, scolecodonts, and graptolites were also recovered from the siliceous rock fragments. Five genera and seven species of chitinozoans, four genera and five species of conodonts, and two uncertain taxa of graptolites were identified. Their biostratigraphy indicates that the Alaskan radiolarian fauna belongs to the upper Aeronian to lower Telychian of the Llandoverian.

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