The diatom record from beneath the West Antarctic Ice Sheet and the global proxy perspective
Recent glaciological evaluation and modeling of the marine-based West Antarctic Ice Sheet (WAIS) support the possibility that the WAIS disintegrated during one or more Pleistocene interglacial period(s). The magnitude of sea level and oxygen isotope variation during certain late-Pleistocene intergla...
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ftnasantrs:oai:casi.ntrs.nasa.gov:19930022693 2023-05-15T14:04:19+02:00 The diatom record from beneath the West Antarctic Ice Sheet and the global proxy perspective Scherer, Reed P. Unclassified, Unlimited, Publicly available Jul 1, 1993 http://ntrs.nasa.gov/search.jsp?R=19930022693 unknown http://ntrs.nasa.gov/search.jsp?R=19930022693 Accession ID: 93N31882 No Copyright Other Sources 46 NASA. Goddard Space Flight Center, The First Annual West Antarctic Ice Sheet (WAIS) Science Workshop; p 6 1993 ftnasantrs 2012-02-15T19:56:21Z Recent glaciological evaluation and modeling of the marine-based West Antarctic Ice Sheet (WAIS) support the possibility that the WAIS disintegrated during one or more Pleistocene interglacial period(s). The magnitude of sea level and oxygen isotope variation during certain late-Pleistocene interglacial periods is also consistent with the possibility of major retreat of the WAIS. Although oxygen isotopes from deep-sea sediments provide the best available proxy record for global ice volume (despite the ambiguities in the record), the source of ice volume changes must be hypothesized. Based on the intensity of interglacial isotopic shifts recorded in Southern Ocean marine sedimentary records, stage 11 (400,000 years ago) is the strongest candidate for WAIS collapse, but the records for stages 9, 7, and 5.5 are all consistent with the possibility of multiple late-Pleistocene collapses. Seismic reflection studies through the WAIS have revealed thick successions of strata with seismic characteristics comparable to upper Tertiary marine sediments. Small samples of glacial diamictons from beneath the ice sheet have been collected via hot-water drilled access holes. These sediments include mixed diatom assemblages of varying ages. Late-Miocene diatoms dominate many samples, probably reflecting marine deposition in West Antarctic basins prior to development of a dominantly glacial phase in West Antarctica. In addition to late-Miocene diatoms, samples from Upstream B (1988/89) contain rare post-Miocene diatoms, many of which imply deposition in the West Antarctic interior during one or more Pleistocene deglaciation periods. Age-diagnostic fossils in glacial sediments beneath ice sheets provide relatively coarse chronostratigraphic control, but they do contain direct evidence of regional deglaciation. Thus, sub-glacial till samples provide the evidence regarding the source of ice sheet variability seen in well-dated proxy records. Combined, these independent data sets can provide a more comprehensive and less speculative interpretation of the history of past glacial minima in currently glaciated polar regions. Other/Unknown Material Antarc* Antarctic Antarctica Ice Sheet Southern Ocean West Antarctica NASA Technical Reports Server (NTRS) Antarctic Southern Ocean West Antarctica West Antarctic Ice Sheet |
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46 Scherer, Reed P. The diatom record from beneath the West Antarctic Ice Sheet and the global proxy perspective |
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description |
Recent glaciological evaluation and modeling of the marine-based West Antarctic Ice Sheet (WAIS) support the possibility that the WAIS disintegrated during one or more Pleistocene interglacial period(s). The magnitude of sea level and oxygen isotope variation during certain late-Pleistocene interglacial periods is also consistent with the possibility of major retreat of the WAIS. Although oxygen isotopes from deep-sea sediments provide the best available proxy record for global ice volume (despite the ambiguities in the record), the source of ice volume changes must be hypothesized. Based on the intensity of interglacial isotopic shifts recorded in Southern Ocean marine sedimentary records, stage 11 (400,000 years ago) is the strongest candidate for WAIS collapse, but the records for stages 9, 7, and 5.5 are all consistent with the possibility of multiple late-Pleistocene collapses. Seismic reflection studies through the WAIS have revealed thick successions of strata with seismic characteristics comparable to upper Tertiary marine sediments. Small samples of glacial diamictons from beneath the ice sheet have been collected via hot-water drilled access holes. These sediments include mixed diatom assemblages of varying ages. Late-Miocene diatoms dominate many samples, probably reflecting marine deposition in West Antarctic basins prior to development of a dominantly glacial phase in West Antarctica. In addition to late-Miocene diatoms, samples from Upstream B (1988/89) contain rare post-Miocene diatoms, many of which imply deposition in the West Antarctic interior during one or more Pleistocene deglaciation periods. Age-diagnostic fossils in glacial sediments beneath ice sheets provide relatively coarse chronostratigraphic control, but they do contain direct evidence of regional deglaciation. Thus, sub-glacial till samples provide the evidence regarding the source of ice sheet variability seen in well-dated proxy records. Combined, these independent data sets can provide a more comprehensive and less speculative interpretation of the history of past glacial minima in currently glaciated polar regions. |
format |
Other/Unknown Material |
author |
Scherer, Reed P. |
author_facet |
Scherer, Reed P. |
author_sort |
Scherer, Reed P. |
title |
The diatom record from beneath the West Antarctic Ice Sheet and the global proxy perspective |
title_short |
The diatom record from beneath the West Antarctic Ice Sheet and the global proxy perspective |
title_full |
The diatom record from beneath the West Antarctic Ice Sheet and the global proxy perspective |
title_fullStr |
The diatom record from beneath the West Antarctic Ice Sheet and the global proxy perspective |
title_full_unstemmed |
The diatom record from beneath the West Antarctic Ice Sheet and the global proxy perspective |
title_sort |
diatom record from beneath the west antarctic ice sheet and the global proxy perspective |
publishDate |
1993 |
url |
http://ntrs.nasa.gov/search.jsp?R=19930022693 |
op_coverage |
Unclassified, Unlimited, Publicly available |
geographic |
Antarctic Southern Ocean West Antarctica West Antarctic Ice Sheet |
geographic_facet |
Antarctic Southern Ocean West Antarctica West Antarctic Ice Sheet |
genre |
Antarc* Antarctic Antarctica Ice Sheet Southern Ocean West Antarctica |
genre_facet |
Antarc* Antarctic Antarctica Ice Sheet Southern Ocean West Antarctica |
op_source |
Other Sources |
op_relation |
http://ntrs.nasa.gov/search.jsp?R=19930022693 Accession ID: 93N31882 |
op_rights |
No Copyright |
_version_ |
1766275350918070272 |