Paleoclimatic Significance of Chemical Weathering in Loess-Derived Paleosols of Subarctic Central Alaska
Chemical weathering in soils has not been studied extensively in high-latitude regions. Loess sequences with modern soils and paleosols are present in much of subarctic Alaska, and allow an assessment of present and past chemical weathering. Five sections were studied in detail in the Fairbanks, Ala...
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ftunivnebraskali:oai:digitalcommons.unl.edu:usgsstaffpub-1150 2023-11-12T04:26:57+01:00 Paleoclimatic Significance of Chemical Weathering in Loess-Derived Paleosols of Subarctic Central Alaska Muhs, Daniel R. Ager, Thomas A. Skipp, Gary Beann, Jossh Budahn, James McGeehin, John P 2008-01-01T08:00:00Z application/pdf https://digitalcommons.unl.edu/usgsstaffpub/151 https://digitalcommons.unl.edu/context/usgsstaffpub/article/1150/viewcontent/Muhs_AAAR_2008_Paleoclimate_significance.pdf unknown DigitalCommons@University of Nebraska - Lincoln https://digitalcommons.unl.edu/usgsstaffpub/151 https://digitalcommons.unl.edu/context/usgsstaffpub/article/1150/viewcontent/Muhs_AAAR_2008_Paleoclimate_significance.pdf USGS Staff -- Published Research Earth Sciences text 2008 ftunivnebraskali 2023-10-30T10:37:27Z Chemical weathering in soils has not been studied extensively in high-latitude regions. Loess sequences with modern soils and paleosols are present in much of subarctic Alaska, and allow an assessment of present and past chemical weathering. Five sections were studied in detail in the Fairbanks, Alaska, area. Paleosols likely date to mid-Pleistocene interglacials, the last interglacial, and early-to-mid- Wisconsin interstadials. Ratios of mobile (Na, Ca, Mg, Si) to immobile (Ti or Zr) elements indicate that modern soils and most interstadial and interglacial paleosols are characterized by significant chemical weathering. Na2O/TiO2 is lower in modern soils and most paleosols compared to parent loess, indicating depletion of plagioclase. In the clay fraction, smectite is present in Tanana and Yukon River source sediments, but is absent or poorly expressed in modern soils and paleosols, indicating depletion of this mineral also. Loss of both plagioclase and smectite is well expressed in soils and paleosols as lower SiO2/TiO2. Carbonates are present in the river source sediments, but based on CaO/TiO2, they are depleted in soils and most paleosols (with one exception in the early-to-mid-Wisconsin period). Thus, most soil-forming intervals during past interglacial and interstadial periods in Alaska had climatic regimes that were at least as favorable to mineral weathering as today, and suggest boreal forest or acidic tundra vegetation. Text Subarctic Tundra Yukon river Alaska Yukon University of Nebraska-Lincoln: DigitalCommons@UNL Yukon Fairbanks |
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Open Polar |
collection |
University of Nebraska-Lincoln: DigitalCommons@UNL |
op_collection_id |
ftunivnebraskali |
language |
unknown |
topic |
Earth Sciences |
spellingShingle |
Earth Sciences Muhs, Daniel R. Ager, Thomas A. Skipp, Gary Beann, Jossh Budahn, James McGeehin, John P Paleoclimatic Significance of Chemical Weathering in Loess-Derived Paleosols of Subarctic Central Alaska |
topic_facet |
Earth Sciences |
description |
Chemical weathering in soils has not been studied extensively in high-latitude regions. Loess sequences with modern soils and paleosols are present in much of subarctic Alaska, and allow an assessment of present and past chemical weathering. Five sections were studied in detail in the Fairbanks, Alaska, area. Paleosols likely date to mid-Pleistocene interglacials, the last interglacial, and early-to-mid- Wisconsin interstadials. Ratios of mobile (Na, Ca, Mg, Si) to immobile (Ti or Zr) elements indicate that modern soils and most interstadial and interglacial paleosols are characterized by significant chemical weathering. Na2O/TiO2 is lower in modern soils and most paleosols compared to parent loess, indicating depletion of plagioclase. In the clay fraction, smectite is present in Tanana and Yukon River source sediments, but is absent or poorly expressed in modern soils and paleosols, indicating depletion of this mineral also. Loss of both plagioclase and smectite is well expressed in soils and paleosols as lower SiO2/TiO2. Carbonates are present in the river source sediments, but based on CaO/TiO2, they are depleted in soils and most paleosols (with one exception in the early-to-mid-Wisconsin period). Thus, most soil-forming intervals during past interglacial and interstadial periods in Alaska had climatic regimes that were at least as favorable to mineral weathering as today, and suggest boreal forest or acidic tundra vegetation. |
format |
Text |
author |
Muhs, Daniel R. Ager, Thomas A. Skipp, Gary Beann, Jossh Budahn, James McGeehin, John P |
author_facet |
Muhs, Daniel R. Ager, Thomas A. Skipp, Gary Beann, Jossh Budahn, James McGeehin, John P |
author_sort |
Muhs, Daniel R. |
title |
Paleoclimatic Significance of Chemical Weathering in Loess-Derived Paleosols of Subarctic Central Alaska |
title_short |
Paleoclimatic Significance of Chemical Weathering in Loess-Derived Paleosols of Subarctic Central Alaska |
title_full |
Paleoclimatic Significance of Chemical Weathering in Loess-Derived Paleosols of Subarctic Central Alaska |
title_fullStr |
Paleoclimatic Significance of Chemical Weathering in Loess-Derived Paleosols of Subarctic Central Alaska |
title_full_unstemmed |
Paleoclimatic Significance of Chemical Weathering in Loess-Derived Paleosols of Subarctic Central Alaska |
title_sort |
paleoclimatic significance of chemical weathering in loess-derived paleosols of subarctic central alaska |
publisher |
DigitalCommons@University of Nebraska - Lincoln |
publishDate |
2008 |
url |
https://digitalcommons.unl.edu/usgsstaffpub/151 https://digitalcommons.unl.edu/context/usgsstaffpub/article/1150/viewcontent/Muhs_AAAR_2008_Paleoclimate_significance.pdf |
geographic |
Yukon Fairbanks |
geographic_facet |
Yukon Fairbanks |
genre |
Subarctic Tundra Yukon river Alaska Yukon |
genre_facet |
Subarctic Tundra Yukon river Alaska Yukon |
op_source |
USGS Staff -- Published Research |
op_relation |
https://digitalcommons.unl.edu/usgsstaffpub/151 https://digitalcommons.unl.edu/context/usgsstaffpub/article/1150/viewcontent/Muhs_AAAR_2008_Paleoclimate_significance.pdf |
_version_ |
1782340739825401856 |