Orbital Forcing of West and East Antarctic Ice Sheets 3.8-3.0 Ma: A Climate Analogue in Weddell Sea ODP Site 697:
As climate change intensifies and the world begins to feel its impacts, scientists are looking to past climatically similar periods to understand how our planet will respond. During the Pliocene Epoch (5.33-2.58 millions of years ago), the West Antarctic Ice Sheet (WAIS) nearly de-glaciated under pe...
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ftwesleyanu:oai:digitalcollections.wesleyan.edu:ir_697 2023-05-15T13:59:40+02:00 Orbital Forcing of West and East Antarctic Ice Sheets 3.8-3.0 Ma: A Climate Analogue in Weddell Sea ODP Site 697: Cullen, Kate (Kate Cullen) (Author) (Suzanne O'Connell) (Thesis advisor) (author) () (Committee member) (Degree grantor) 103 pages electronic application/pdf https://doi.org/10.14418/wes01.1.1281 https://digitalcollections.wesleyan.edu/islandora/object/ir%3A697/datastream/TN/view/Orbital%20Forcing%20of%20West%20and%20East%20Antarctic%20Ice%20Sheets%203.8-3.0%20Ma%3A%20A%20Climate%20Analogue%20in%20Weddell%20Sea%20ODP%20Site%20697.jpg https://digitalcollections.wesleyan.edu/object/ir-697 eng eng In Copyright – Non-Commercial Use Permitted (InC-NC) --- Text theses Dissertation/Thesis ftwesleyanu https://doi.org/10.14418/wes01.1.1281 2022-02-04T20:42:21Z As climate change intensifies and the world begins to feel its impacts, scientists are looking to past climatically similar periods to understand how our planet will respond. During the Pliocene Epoch (5.33-2.58 millions of years ago), the West Antarctic Ice Sheet (WAIS) nearly de-glaciated under peak CO2 concentrations of ~400 ppm (Fedorov et al., 2013) and global average temperatures 2-3°C warmer than pre-industrial values (Yamane et al., 2015). The sensitivity of the WAIS to CO2 and ocean temperature fluctuations on orbital timescales is well established (DeConto & Pollard, 2003; Naish et al., 2009). A more controversial question is how sensitive the East Antarctic Ice Sheet (EAIS) is to similar forcings. To address this question, we analyze sedimentological changes in Antarctic Weddell Sea ODP Site 697 marine cores deposited 3.8-3.0 Ma for cyclicities in ice sheet dynamics and bottom water fluctuations. Spectral analysis of fine fraction mineral assemblages identifies smectite, illite, chert, chalcedony, SiO2, garnet and feldspar. Continuous detrital smectite deposition points to high Antarctic Bottom Water (AABW) circulation through the Jane Basin 3.8 to 3.0 Ma. Varimax-rotated principal component analysis and wavelet analysis of elemental count ratios suggest Jane Basin sediment deposition transitioned from a dominant eccentricity forcing with obliquity inputs to a dominant precession forcing modulated by eccentricity at ~3.3 Ma. Derived linear sedimentation rates slow from ~6.3 cm/kyr between 3.78 and 3.21 Ma to 4.74 cm/kyr between 3.14 and 3.03 Ma. These findings indicate that EAIS and WAIS behavior as moderated by an eccentricity and obliquity forcing during Pliocene peak warming and a precession forcing during cooler conditions after ~3.3 Ma. 2016 Old URL: https://wesscholar.wesleyan.edu/etd_hon_theses/1655 In Copyright – Non-Commercial Use Permitted (InC-NC) Thesis Antarc* Antarctic Ice Sheet Weddell Sea Wesleyan University: WesScholar Antarctic East Antarctic Ice Sheet Jane Basin ENVELOPE(-41.909,-41.909,-61.890,-61.890) Pollard ENVELOPE(64.617,64.617,-70.467,-70.467) Weddell Weddell Sea West Antarctic Ice Sheet |
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Wesleyan University: WesScholar |
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English |
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--- Orbital Forcing of West and East Antarctic Ice Sheets 3.8-3.0 Ma: A Climate Analogue in Weddell Sea ODP Site 697: |
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description |
As climate change intensifies and the world begins to feel its impacts, scientists are looking to past climatically similar periods to understand how our planet will respond. During the Pliocene Epoch (5.33-2.58 millions of years ago), the West Antarctic Ice Sheet (WAIS) nearly de-glaciated under peak CO2 concentrations of ~400 ppm (Fedorov et al., 2013) and global average temperatures 2-3°C warmer than pre-industrial values (Yamane et al., 2015). The sensitivity of the WAIS to CO2 and ocean temperature fluctuations on orbital timescales is well established (DeConto & Pollard, 2003; Naish et al., 2009). A more controversial question is how sensitive the East Antarctic Ice Sheet (EAIS) is to similar forcings. To address this question, we analyze sedimentological changes in Antarctic Weddell Sea ODP Site 697 marine cores deposited 3.8-3.0 Ma for cyclicities in ice sheet dynamics and bottom water fluctuations. Spectral analysis of fine fraction mineral assemblages identifies smectite, illite, chert, chalcedony, SiO2, garnet and feldspar. Continuous detrital smectite deposition points to high Antarctic Bottom Water (AABW) circulation through the Jane Basin 3.8 to 3.0 Ma. Varimax-rotated principal component analysis and wavelet analysis of elemental count ratios suggest Jane Basin sediment deposition transitioned from a dominant eccentricity forcing with obliquity inputs to a dominant precession forcing modulated by eccentricity at ~3.3 Ma. Derived linear sedimentation rates slow from ~6.3 cm/kyr between 3.78 and 3.21 Ma to 4.74 cm/kyr between 3.14 and 3.03 Ma. These findings indicate that EAIS and WAIS behavior as moderated by an eccentricity and obliquity forcing during Pliocene peak warming and a precession forcing during cooler conditions after ~3.3 Ma. 2016 Old URL: https://wesscholar.wesleyan.edu/etd_hon_theses/1655 In Copyright – Non-Commercial Use Permitted (InC-NC) |
author2 |
Cullen, Kate (Kate Cullen) (Author) (Suzanne O'Connell) (Thesis advisor) (author) () (Committee member) (Degree grantor) |
format |
Thesis |
title |
Orbital Forcing of West and East Antarctic Ice Sheets 3.8-3.0 Ma: A Climate Analogue in Weddell Sea ODP Site 697: |
title_short |
Orbital Forcing of West and East Antarctic Ice Sheets 3.8-3.0 Ma: A Climate Analogue in Weddell Sea ODP Site 697: |
title_full |
Orbital Forcing of West and East Antarctic Ice Sheets 3.8-3.0 Ma: A Climate Analogue in Weddell Sea ODP Site 697: |
title_fullStr |
Orbital Forcing of West and East Antarctic Ice Sheets 3.8-3.0 Ma: A Climate Analogue in Weddell Sea ODP Site 697: |
title_full_unstemmed |
Orbital Forcing of West and East Antarctic Ice Sheets 3.8-3.0 Ma: A Climate Analogue in Weddell Sea ODP Site 697: |
title_sort |
orbital forcing of west and east antarctic ice sheets 3.8-3.0 ma: a climate analogue in weddell sea odp site 697: |
url |
https://doi.org/10.14418/wes01.1.1281 https://digitalcollections.wesleyan.edu/islandora/object/ir%3A697/datastream/TN/view/Orbital%20Forcing%20of%20West%20and%20East%20Antarctic%20Ice%20Sheets%203.8-3.0%20Ma%3A%20A%20Climate%20Analogue%20in%20Weddell%20Sea%20ODP%20Site%20697.jpg https://digitalcollections.wesleyan.edu/object/ir-697 |
long_lat |
ENVELOPE(-41.909,-41.909,-61.890,-61.890) ENVELOPE(64.617,64.617,-70.467,-70.467) |
geographic |
Antarctic East Antarctic Ice Sheet Jane Basin Pollard Weddell Weddell Sea West Antarctic Ice Sheet |
geographic_facet |
Antarctic East Antarctic Ice Sheet Jane Basin Pollard Weddell Weddell Sea West Antarctic Ice Sheet |
genre |
Antarc* Antarctic Ice Sheet Weddell Sea |
genre_facet |
Antarc* Antarctic Ice Sheet Weddell Sea |
op_rights |
In Copyright – Non-Commercial Use Permitted (InC-NC) |
op_doi |
https://doi.org/10.14418/wes01.1.1281 |
_version_ |
1766268337940070400 |