Diamictic sediments within high Arctic lake sediment cores: evidence for lake ice rafting along the lateral glacial margin
Sediment cores from six small lake basins in the Canadian high Arctic reveal a gravel‐rich (≤30% by weight) to gravel‐poor (≥2%) diamict facies underlying massive, post‐glacial, clayey silt. Ten other lakes contain a second diamict facies within what are interpreted to be glaciolacustrine sedimentar...
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crwiley:10.1046/j.1365-3091.2000.00347.x 2024-09-09T19:25:02+00:00 Diamictic sediments within high Arctic lake sediment cores: evidence for lake ice rafting along the lateral glacial margin Smith, I. Rod 2000 http://dx.doi.org/10.1046/j.1365-3091.2000.00347.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1046%2Fj.1365-3091.2000.00347.x https://onlinelibrary.wiley.com/doi/pdf/10.1046/j.1365-3091.2000.00347.x en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Sedimentology volume 47, issue 6, page 1157-1179 ISSN 0037-0746 1365-3091 journal-article 2000 crwiley https://doi.org/10.1046/j.1365-3091.2000.00347.x 2024-07-25T04:21:37Z Sediment cores from six small lake basins in the Canadian high Arctic reveal a gravel‐rich (≤30% by weight) to gravel‐poor (≥2%) diamict facies underlying massive, post‐glacial, clayey silt. Ten other lakes contain a second diamict facies within what are interpreted to be glaciolacustrine sedimentary assemblages. The sedimentology, clast fabrics and fossil remains (diatoms, ostracodes and chironomid head capsules) within both diamict facies suggest that these deposits are not tills. Clast fabrics yielded low S 1 (0·41–0·57) and high S 3 (0·09–0·22) eigenvalues, placing them within the range of ice‐rafted diamictons and glacigenic sediment flows. The high percentage of clast dip angles >45° (15–61%), random clast azimuth and lower diamict contacts conformable to underlying current‐bedded sediment favours an origin as a rain‐out or settling deposit. Samples of the matrix and scrapings of clasts from the diamicts revealed a diatom assemblage dominated by littoral and planktonic forms, such as are found in the littoral regions of the lakes today. This contrasts sharply with the assemblages within the overlying clayey silt, in which benthic forms predominate. Clasts are thus interpreted to have been rafted from the littoral areas of the lake. The process proposed to explain this is rafting by the lake ice cover in a glacial‐marginal environment. Early season meltwater, impounded along the lateral margin of retreating cold‐based glaciers, would buoyantly lift the lake ice cover and any adfrozen lake sediment. Higher lake levels and increased areal extent of seasonal freeze‐on between the lake ice cover and the lake bed would allow the redeposition of littoral sediments to the benthic regions through greater lateral shifting of the ice cover as it broke up. Incision by meltwater streams into the lateral glacial margins would later isolate the lake, allowing seasonal warming of lake water, enough to support the growth and maturation of the ostracode and chironomid species found as fossils within the diamicts. Article in Journal/Newspaper Arctic Wiley Online Library Arctic Arctic Lake ENVELOPE(-130.826,-130.826,57.231,57.231) Sedimentology 47 6 1157 1179 |
institution |
Open Polar |
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Wiley Online Library |
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crwiley |
language |
English |
description |
Sediment cores from six small lake basins in the Canadian high Arctic reveal a gravel‐rich (≤30% by weight) to gravel‐poor (≥2%) diamict facies underlying massive, post‐glacial, clayey silt. Ten other lakes contain a second diamict facies within what are interpreted to be glaciolacustrine sedimentary assemblages. The sedimentology, clast fabrics and fossil remains (diatoms, ostracodes and chironomid head capsules) within both diamict facies suggest that these deposits are not tills. Clast fabrics yielded low S 1 (0·41–0·57) and high S 3 (0·09–0·22) eigenvalues, placing them within the range of ice‐rafted diamictons and glacigenic sediment flows. The high percentage of clast dip angles >45° (15–61%), random clast azimuth and lower diamict contacts conformable to underlying current‐bedded sediment favours an origin as a rain‐out or settling deposit. Samples of the matrix and scrapings of clasts from the diamicts revealed a diatom assemblage dominated by littoral and planktonic forms, such as are found in the littoral regions of the lakes today. This contrasts sharply with the assemblages within the overlying clayey silt, in which benthic forms predominate. Clasts are thus interpreted to have been rafted from the littoral areas of the lake. The process proposed to explain this is rafting by the lake ice cover in a glacial‐marginal environment. Early season meltwater, impounded along the lateral margin of retreating cold‐based glaciers, would buoyantly lift the lake ice cover and any adfrozen lake sediment. Higher lake levels and increased areal extent of seasonal freeze‐on between the lake ice cover and the lake bed would allow the redeposition of littoral sediments to the benthic regions through greater lateral shifting of the ice cover as it broke up. Incision by meltwater streams into the lateral glacial margins would later isolate the lake, allowing seasonal warming of lake water, enough to support the growth and maturation of the ostracode and chironomid species found as fossils within the diamicts. |
format |
Article in Journal/Newspaper |
author |
Smith, I. Rod |
spellingShingle |
Smith, I. Rod Diamictic sediments within high Arctic lake sediment cores: evidence for lake ice rafting along the lateral glacial margin |
author_facet |
Smith, I. Rod |
author_sort |
Smith, I. Rod |
title |
Diamictic sediments within high Arctic lake sediment cores: evidence for lake ice rafting along the lateral glacial margin |
title_short |
Diamictic sediments within high Arctic lake sediment cores: evidence for lake ice rafting along the lateral glacial margin |
title_full |
Diamictic sediments within high Arctic lake sediment cores: evidence for lake ice rafting along the lateral glacial margin |
title_fullStr |
Diamictic sediments within high Arctic lake sediment cores: evidence for lake ice rafting along the lateral glacial margin |
title_full_unstemmed |
Diamictic sediments within high Arctic lake sediment cores: evidence for lake ice rafting along the lateral glacial margin |
title_sort |
diamictic sediments within high arctic lake sediment cores: evidence for lake ice rafting along the lateral glacial margin |
publisher |
Wiley |
publishDate |
2000 |
url |
http://dx.doi.org/10.1046/j.1365-3091.2000.00347.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1046%2Fj.1365-3091.2000.00347.x https://onlinelibrary.wiley.com/doi/pdf/10.1046/j.1365-3091.2000.00347.x |
long_lat |
ENVELOPE(-130.826,-130.826,57.231,57.231) |
geographic |
Arctic Arctic Lake |
geographic_facet |
Arctic Arctic Lake |
genre |
Arctic |
genre_facet |
Arctic |
op_source |
Sedimentology volume 47, issue 6, page 1157-1179 ISSN 0037-0746 1365-3091 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1046/j.1365-3091.2000.00347.x |
container_title |
Sedimentology |
container_volume |
47 |
container_issue |
6 |
container_start_page |
1157 |
op_container_end_page |
1179 |
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1809894840400347136 |