Environments of Aeolian Deposition in South-Central Nebraska During the Last Glacial Maximum
The Peoria loess of south-central Nebraska, deposited approximately during the last Glacial Maximum, can be subdivided into three zones: an upper laminated loess and a lower massive loess, separated by a dark gley zone in which bison bones and spruce charcoal are found. The lower Peoria unit is char...
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1994
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ftunivnebraskali:oai:digitalcommons.unl.edu:diffendal-1029 2023-11-12T04:24:35+01:00 Environments of Aeolian Deposition in South-Central Nebraska During the Last Glacial Maximum Feng, Zhao-Dong Johnson, William C. Diffendal,, Robert F., Jr. 1994-01-01T08:00:00Z application/pdf https://digitalcommons.unl.edu/diffendal/30 https://digitalcommons.unl.edu/context/diffendal/article/1029/viewcontent/Diffendal_PG_1994_Environments_of_Aeolian__DC_VERSION.pdf unknown DigitalCommons@University of Nebraska - Lincoln https://digitalcommons.unl.edu/diffendal/30 https://digitalcommons.unl.edu/context/diffendal/article/1029/viewcontent/Diffendal_PG_1994_Environments_of_Aeolian__DC_VERSION.pdf Robert F. Diffendal, Jr., Publications Peoria loess dust Great Plains last Glacial Maximum Earth Sciences Geology Geomorphology Hydrology Stratigraphy text 1994 ftunivnebraskali 2023-10-30T11:28:24Z The Peoria loess of south-central Nebraska, deposited approximately during the last Glacial Maximum, can be subdivided into three zones: an upper laminated loess and a lower massive loess, separated by a dark gley zone in which bison bones and spruce charcoal are found. The lower Peoria unit is characterized by high organic matter content, relatively high bulk density, and common root channels. The upper Peoria unit has rhythmic patterns of two orders: strongly gleyed and weakly gleyed zones alternating in couplets about 2-5 m thick, and coarse- and fine-grained laminae of second order, about 2-4 mm thick. The strongly gleyed zones are relatively low in magnetic susceptibility and contain lenses with abundant fossil plant debris. They may have formed in active zones on top of permafrost during relatively cold and probably moist intervals, with magnetic susceptibility secondarily lowered in the redox environment. Magnetic susceptibility also indicates the possible existence of first-order rhythmic patterns in the lower massive loess. Each of the ten susceptibility oscillations within Peoria loess has a mean duration of about 1000 years, assuming that the loess was deposited between approximately 20,000-22,000 and 10,000-10,500 yr BP. The second-order laminae, close to the expected mean annual accumulation rate of Peoria loess, may be due to seasonal variation in wind intensity or to secondary grain sorting of niveoeolian deposits. Text permafrost University of Nebraska-Lincoln: DigitalCommons@UNL Peoria ENVELOPE(-118.286,-118.286,55.617,55.617) |
institution |
Open Polar |
collection |
University of Nebraska-Lincoln: DigitalCommons@UNL |
op_collection_id |
ftunivnebraskali |
language |
unknown |
topic |
Peoria loess dust Great Plains last Glacial Maximum Earth Sciences Geology Geomorphology Hydrology Stratigraphy |
spellingShingle |
Peoria loess dust Great Plains last Glacial Maximum Earth Sciences Geology Geomorphology Hydrology Stratigraphy Feng, Zhao-Dong Johnson, William C. Diffendal,, Robert F., Jr. Environments of Aeolian Deposition in South-Central Nebraska During the Last Glacial Maximum |
topic_facet |
Peoria loess dust Great Plains last Glacial Maximum Earth Sciences Geology Geomorphology Hydrology Stratigraphy |
description |
The Peoria loess of south-central Nebraska, deposited approximately during the last Glacial Maximum, can be subdivided into three zones: an upper laminated loess and a lower massive loess, separated by a dark gley zone in which bison bones and spruce charcoal are found. The lower Peoria unit is characterized by high organic matter content, relatively high bulk density, and common root channels. The upper Peoria unit has rhythmic patterns of two orders: strongly gleyed and weakly gleyed zones alternating in couplets about 2-5 m thick, and coarse- and fine-grained laminae of second order, about 2-4 mm thick. The strongly gleyed zones are relatively low in magnetic susceptibility and contain lenses with abundant fossil plant debris. They may have formed in active zones on top of permafrost during relatively cold and probably moist intervals, with magnetic susceptibility secondarily lowered in the redox environment. Magnetic susceptibility also indicates the possible existence of first-order rhythmic patterns in the lower massive loess. Each of the ten susceptibility oscillations within Peoria loess has a mean duration of about 1000 years, assuming that the loess was deposited between approximately 20,000-22,000 and 10,000-10,500 yr BP. The second-order laminae, close to the expected mean annual accumulation rate of Peoria loess, may be due to seasonal variation in wind intensity or to secondary grain sorting of niveoeolian deposits. |
format |
Text |
author |
Feng, Zhao-Dong Johnson, William C. Diffendal,, Robert F., Jr. |
author_facet |
Feng, Zhao-Dong Johnson, William C. Diffendal,, Robert F., Jr. |
author_sort |
Feng, Zhao-Dong |
title |
Environments of Aeolian Deposition in South-Central Nebraska During the Last Glacial Maximum |
title_short |
Environments of Aeolian Deposition in South-Central Nebraska During the Last Glacial Maximum |
title_full |
Environments of Aeolian Deposition in South-Central Nebraska During the Last Glacial Maximum |
title_fullStr |
Environments of Aeolian Deposition in South-Central Nebraska During the Last Glacial Maximum |
title_full_unstemmed |
Environments of Aeolian Deposition in South-Central Nebraska During the Last Glacial Maximum |
title_sort |
environments of aeolian deposition in south-central nebraska during the last glacial maximum |
publisher |
DigitalCommons@University of Nebraska - Lincoln |
publishDate |
1994 |
url |
https://digitalcommons.unl.edu/diffendal/30 https://digitalcommons.unl.edu/context/diffendal/article/1029/viewcontent/Diffendal_PG_1994_Environments_of_Aeolian__DC_VERSION.pdf |
long_lat |
ENVELOPE(-118.286,-118.286,55.617,55.617) |
geographic |
Peoria |
geographic_facet |
Peoria |
genre |
permafrost |
genre_facet |
permafrost |
op_source |
Robert F. Diffendal, Jr., Publications |
op_relation |
https://digitalcommons.unl.edu/diffendal/30 https://digitalcommons.unl.edu/context/diffendal/article/1029/viewcontent/Diffendal_PG_1994_Environments_of_Aeolian__DC_VERSION.pdf |
_version_ |
1782339071785304064 |