FLUVIAL RESPONSE TO LATE QUATERNARY CLIMATIC FLUCTUATIONS, CENTRAL KOBUK VALLEY, NORTHWESTERN ALASKA

Citation
Gm. Ashley et Td. Hamilton, FLUVIAL RESPONSE TO LATE QUATERNARY CLIMATIC FLUCTUATIONS, CENTRAL KOBUK VALLEY, NORTHWESTERN ALASKA, Journal of sedimentary petrology, 63(5), 1993, pp. 814-827
Citations number
55
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Geology
Journal title
ISSN journal
0022-4472
Volume
63
Issue
5
Year of publication
1993
Pages
814 - 827
Database
ISI
SICI code
0022-4472(1993)63:5<814:FRTLQC>2.0.ZU;2-E
Abstract
Much of northwestern Alaska remained unglaciated during the Pleistocen e and thus offers a favorable setting for examining long-term records of high-latitude geological and biological change. Epiguruk, a large c ut bank 3.5 km long and up to 36 m high on the Kobuk River south of th e Brooks Range in eastern Beringia, exposes complex sedimentary succes sions representing cycles of upper Quaternary alluviation and eolian s edimentation, downcutting, and soil formation. A rich record of plants and mammals is also preserved in the section. Deposits of fluvial cha nnels and flood plains, eolian dunes, sand sheets, loess, and ponds, a s well as organic soils (Histosols) are represented. Parallel-bedded f ine sand and coarse silt couplets that commonly contain root structure s, ripple cross-lamination, and silt drapes are flood-plain sediments apparently deposited at the interface of fluvial and eolian environmen ts. Multiple fluvial-to-eolian depositional sequences were caused by i nflux of eolian sediment to the river from intermittently active dune fields south of the Kobuk River. Alluviation in the Kobuk Valley was c oeval with glaciation in the Brooks Range, whereas downcutting occurre d during interstadials when dune stabilization limited sediment supply . The depositional model developed at Epiguruk may be useful in interp reting some of the widespread subhorizontally stratified late-glacial deposits of Europe and North America.