The Last Interglacial in the Labrador Sea
A multi-proxy age model protocol was established using Labrador Sea sediment cores U1305 (57°N,48°W) and U1302 (50°N,45°W). These cores provided centennial-scale surface and deep-water records spanning the last interglacial (153-100ka). Ice rafted debris (IRD) counts and meltwater-runoff proxy Ba/Ca...
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ftuniveastangl:oai:ueaeprints.uea.ac.uk:67637 2023-05-15T13:59:53+02:00 The Last Interglacial in the Labrador Sea Hume, Leila 2018-03 application/pdf https://ueaeprints.uea.ac.uk/id/eprint/67637/ https://ueaeprints.uea.ac.uk/id/eprint/67637/1/Leila_Hume_PhD_Thesis_March_2018.pdf en eng https://ueaeprints.uea.ac.uk/id/eprint/67637/1/Leila_Hume_PhD_Thesis_March_2018.pdf Hume, Leila (2018) The Last Interglacial in the Labrador Sea. Doctoral thesis, University of East Anglia. Thesis NonPeerReviewed 2018 ftuniveastangl 2023-01-30T21:48:38Z A multi-proxy age model protocol was established using Labrador Sea sediment cores U1305 (57°N,48°W) and U1302 (50°N,45°W). These cores provided centennial-scale surface and deep-water records spanning the last interglacial (153-100ka). Ice rafted debris (IRD) counts and meltwater-runoff proxy Ba/Ca were used to investigate ice sheet instabilities; planktonic foraminiferal assemblages, planktonic δ18O and multi-species Mg/Ca records were used to reconstruct temperature and salinity; and fluctuations in Atlantic meridional overturning circulation (AMOC) were inferred from benthic δ13C. Intense cold and ice rafting accompanied Heinrich events H11 (135–130ka) and H12 (140ka), as well as a previously unrecognised Heinrich event (H13; 150–148ka), during which benthic and planktonic δ13C values indicate reduced AMOC and nutrient-rich Antarctic bottom-water (AABW) incursions. During H11, three warm phases preceded cooling and massive IRD pulses. Strongly depleted U1302 planktonic δ18O accompanied all IRD-rich cold periods, particularly H11, attributed to sea-ice formation and enhanced meltwater input. No Younger Dryas-like event was observed. Last interglacial temperatures were 2–5°C warmer in U1305, but similar to modern values at U1302, suggesting differing latitudinal responses to increased insolation (129–126ka). A diatom mat deposited ~128.7–128.6ka in U1305 indicates a proximal subarctic convergence front. Palaeotemperature reconstructions reveal two last interglacial warm maxima. The first (128.5–126.5ka) had the most diverse foraminiferal assemblages and was coeval with continued Greenland ice-sheet melt. A previously reported red layer, linked to a Laurentide outburst flood, has been dated to ~126.5ka and marks the culmination of localised intra-interglacial cooling. Subsequent AABW incursion events suggest rapid AMOC weakening and instability. Mg/Ca results reveal a second warming (123–117ka) associated with a vigorous AMOC, and was attributed to a stronger Irminger Current. IRD, SST and isotopic evidence ... Thesis Antarc* Antarctic Greenland Ice Sheet Labrador Sea Sea ice Subarctic University of East Anglia: UEA Digital Repository Antarctic Greenland |
institution |
Open Polar |
collection |
University of East Anglia: UEA Digital Repository |
op_collection_id |
ftuniveastangl |
language |
English |
description |
A multi-proxy age model protocol was established using Labrador Sea sediment cores U1305 (57°N,48°W) and U1302 (50°N,45°W). These cores provided centennial-scale surface and deep-water records spanning the last interglacial (153-100ka). Ice rafted debris (IRD) counts and meltwater-runoff proxy Ba/Ca were used to investigate ice sheet instabilities; planktonic foraminiferal assemblages, planktonic δ18O and multi-species Mg/Ca records were used to reconstruct temperature and salinity; and fluctuations in Atlantic meridional overturning circulation (AMOC) were inferred from benthic δ13C. Intense cold and ice rafting accompanied Heinrich events H11 (135–130ka) and H12 (140ka), as well as a previously unrecognised Heinrich event (H13; 150–148ka), during which benthic and planktonic δ13C values indicate reduced AMOC and nutrient-rich Antarctic bottom-water (AABW) incursions. During H11, three warm phases preceded cooling and massive IRD pulses. Strongly depleted U1302 planktonic δ18O accompanied all IRD-rich cold periods, particularly H11, attributed to sea-ice formation and enhanced meltwater input. No Younger Dryas-like event was observed. Last interglacial temperatures were 2–5°C warmer in U1305, but similar to modern values at U1302, suggesting differing latitudinal responses to increased insolation (129–126ka). A diatom mat deposited ~128.7–128.6ka in U1305 indicates a proximal subarctic convergence front. Palaeotemperature reconstructions reveal two last interglacial warm maxima. The first (128.5–126.5ka) had the most diverse foraminiferal assemblages and was coeval with continued Greenland ice-sheet melt. A previously reported red layer, linked to a Laurentide outburst flood, has been dated to ~126.5ka and marks the culmination of localised intra-interglacial cooling. Subsequent AABW incursion events suggest rapid AMOC weakening and instability. Mg/Ca results reveal a second warming (123–117ka) associated with a vigorous AMOC, and was attributed to a stronger Irminger Current. IRD, SST and isotopic evidence ... |
format |
Thesis |
author |
Hume, Leila |
spellingShingle |
Hume, Leila The Last Interglacial in the Labrador Sea |
author_facet |
Hume, Leila |
author_sort |
Hume, Leila |
title |
The Last Interglacial in the Labrador Sea |
title_short |
The Last Interglacial in the Labrador Sea |
title_full |
The Last Interglacial in the Labrador Sea |
title_fullStr |
The Last Interglacial in the Labrador Sea |
title_full_unstemmed |
The Last Interglacial in the Labrador Sea |
title_sort |
last interglacial in the labrador sea |
publishDate |
2018 |
url |
https://ueaeprints.uea.ac.uk/id/eprint/67637/ https://ueaeprints.uea.ac.uk/id/eprint/67637/1/Leila_Hume_PhD_Thesis_March_2018.pdf |
geographic |
Antarctic Greenland |
geographic_facet |
Antarctic Greenland |
genre |
Antarc* Antarctic Greenland Ice Sheet Labrador Sea Sea ice Subarctic |
genre_facet |
Antarc* Antarctic Greenland Ice Sheet Labrador Sea Sea ice Subarctic |
op_relation |
https://ueaeprints.uea.ac.uk/id/eprint/67637/1/Leila_Hume_PhD_Thesis_March_2018.pdf Hume, Leila (2018) The Last Interglacial in the Labrador Sea. Doctoral thesis, University of East Anglia. |
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1766268819672662016 |