Middle Pleistocene age of the Nome River glaciation, northwestern Alaska
Abstract During the middle Pleistocene Nome River glaciation of northwestern Alaska, glaciers covered an area an order of magnitude more extensive than during any subsequent glacial intervals. The age of the Nome River glaciation is constrained by laser-fusion 40 Ar/ 39 Ar analyses of basaltic lava...
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Cambridge University Press (CUP)
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crcambridgeupr:10.1016/0033-5894(91)90003-n 2024-06-23T07:53:06+00:00 Middle Pleistocene age of the Nome River glaciation, northwestern Alaska Kaufman, Darrell S. Walter, Robert C. Brigham-Grette, Julie Hopkins, David M. 1991 http://dx.doi.org/10.1016/0033-5894(91)90003-n http://api.elsevier.com/content/article/PII:003358949190003N?httpAccept=text/xml http://api.elsevier.com/content/article/PII:003358949190003N?httpAccept=text/plain https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0033589400033391 en eng Cambridge University Press (CUP) https://www.cambridge.org/core/terms Quaternary Research volume 36, issue 3, page 277-293 ISSN 0033-5894 1096-0287 journal-article 1991 crcambridgeupr https://doi.org/10.1016/0033-5894(91)90003-n 2024-06-05T04:04:54Z Abstract During the middle Pleistocene Nome River glaciation of northwestern Alaska, glaciers covered an area an order of magnitude more extensive than during any subsequent glacial intervals. The age of the Nome River glaciation is constrained by laser-fusion 40 Ar/ 39 Ar analyses of basaltic lava that overlies Nome River drift at Minnie Creek, central Seward Peninsula, that average 470,000 ± 190,000 yr (±1σ). Milligram-size subsamples of the lava were dated to identify and eliminate extraneous 40 Ar enrichments that rendered the mean of conventional K-Ar dates on larger bulk samples of the same flow too old (700,000 ± 570,000 yr). While the 40 Ar/ 39 Ar analyses provide a minimum limiting age for the Nome River glaciation, maximum ages are provided by a provisional K-Ar date on a basaltic lava flow that underlies the Nome River drift at nearby Lave Creek, by paleomagnetic determinations of the drift itself at and near the type locality, and by amino acid epimerization analysis of molluscan fossils from nearshore sediments of the Anvilian marine transgression that underlie Nome River drift on the coastal plain at Nome. Taken together, the new age data indicate that the glaciation took place between 580,000 and 280,000 yr ago. The altitude of the Anvilian deposits suggests that eustatic sea level during the Anvilian transgression rose at least as high as and probably higher than during the last interglacial transgression; by correlation with the marine oxygen-isotope record, the transgression probably dates to stage 11 at 410,000 yr, and the Nome River glaciation is younger still. Analyses of floor altitudes of presumed Nome River cirques indicate that the Nome River regional snowline depression was at least twice that of the maximum late Wisconsin. The cause of the enhanced snowline lowering appears to be related to greater availability of moisture in northwestern Alaska during the middle Pleistocene. Article in Journal/Newspaper glaciers Nome Seward Peninsula Alaska Cambridge University Press Quaternary Research 36 3 277 293 |
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Open Polar |
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Cambridge University Press |
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crcambridgeupr |
language |
English |
description |
Abstract During the middle Pleistocene Nome River glaciation of northwestern Alaska, glaciers covered an area an order of magnitude more extensive than during any subsequent glacial intervals. The age of the Nome River glaciation is constrained by laser-fusion 40 Ar/ 39 Ar analyses of basaltic lava that overlies Nome River drift at Minnie Creek, central Seward Peninsula, that average 470,000 ± 190,000 yr (±1σ). Milligram-size subsamples of the lava were dated to identify and eliminate extraneous 40 Ar enrichments that rendered the mean of conventional K-Ar dates on larger bulk samples of the same flow too old (700,000 ± 570,000 yr). While the 40 Ar/ 39 Ar analyses provide a minimum limiting age for the Nome River glaciation, maximum ages are provided by a provisional K-Ar date on a basaltic lava flow that underlies the Nome River drift at nearby Lave Creek, by paleomagnetic determinations of the drift itself at and near the type locality, and by amino acid epimerization analysis of molluscan fossils from nearshore sediments of the Anvilian marine transgression that underlie Nome River drift on the coastal plain at Nome. Taken together, the new age data indicate that the glaciation took place between 580,000 and 280,000 yr ago. The altitude of the Anvilian deposits suggests that eustatic sea level during the Anvilian transgression rose at least as high as and probably higher than during the last interglacial transgression; by correlation with the marine oxygen-isotope record, the transgression probably dates to stage 11 at 410,000 yr, and the Nome River glaciation is younger still. Analyses of floor altitudes of presumed Nome River cirques indicate that the Nome River regional snowline depression was at least twice that of the maximum late Wisconsin. The cause of the enhanced snowline lowering appears to be related to greater availability of moisture in northwestern Alaska during the middle Pleistocene. |
format |
Article in Journal/Newspaper |
author |
Kaufman, Darrell S. Walter, Robert C. Brigham-Grette, Julie Hopkins, David M. |
spellingShingle |
Kaufman, Darrell S. Walter, Robert C. Brigham-Grette, Julie Hopkins, David M. Middle Pleistocene age of the Nome River glaciation, northwestern Alaska |
author_facet |
Kaufman, Darrell S. Walter, Robert C. Brigham-Grette, Julie Hopkins, David M. |
author_sort |
Kaufman, Darrell S. |
title |
Middle Pleistocene age of the Nome River glaciation, northwestern Alaska |
title_short |
Middle Pleistocene age of the Nome River glaciation, northwestern Alaska |
title_full |
Middle Pleistocene age of the Nome River glaciation, northwestern Alaska |
title_fullStr |
Middle Pleistocene age of the Nome River glaciation, northwestern Alaska |
title_full_unstemmed |
Middle Pleistocene age of the Nome River glaciation, northwestern Alaska |
title_sort |
middle pleistocene age of the nome river glaciation, northwestern alaska |
publisher |
Cambridge University Press (CUP) |
publishDate |
1991 |
url |
http://dx.doi.org/10.1016/0033-5894(91)90003-n http://api.elsevier.com/content/article/PII:003358949190003N?httpAccept=text/xml http://api.elsevier.com/content/article/PII:003358949190003N?httpAccept=text/plain https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0033589400033391 |
genre |
glaciers Nome Seward Peninsula Alaska |
genre_facet |
glaciers Nome Seward Peninsula Alaska |
op_source |
Quaternary Research volume 36, issue 3, page 277-293 ISSN 0033-5894 1096-0287 |
op_rights |
https://www.cambridge.org/core/terms |
op_doi |
https://doi.org/10.1016/0033-5894(91)90003-n |
container_title |
Quaternary Research |
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36 |
container_issue |
3 |
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277 |
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293 |
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1802644583901822976 |