A 600 kyr reconstruction of deep Arctic seawater δ 18 O from benthic foraminiferal δ 18 O and ostracode Mg ∕ Ca paleothermometry
The oxygen isotopic composition of benthic foraminiferal tests (δ18Ob) is one of the pre-eminent tools for correlating marine sediments and interpreting past terrestrial ice volume and deep-ocean temperatures. Despite the prevalence of δ18Ob applications to marine sediment cores over the Quaternary,...
Published in: | Climate of the Past |
---|---|
Main Authors: | , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
2023
|
Subjects: | |
Online Access: | http://hdl.handle.net/21.11116/0000-000D-8BF8-F |
id |
ftpubman:oai:pure.mpg.de:item_3524006 |
---|---|
record_format |
openpolar |
spelling |
ftpubman:oai:pure.mpg.de:item_3524006 2023-09-05T13:16:07+02:00 A 600 kyr reconstruction of deep Arctic seawater δ 18 O from benthic foraminiferal δ 18 O and ostracode Mg ∕ Ca paleothermometry Farmer, J. Keller, K. Poirier, R. Dwyer, G. Schaller, M. Coxall, H. O'Regan, M. Cronin, T. 2023-03-14 http://hdl.handle.net/21.11116/0000-000D-8BF8-F eng eng info:eu-repo/semantics/altIdentifier/doi/10.5194/cp-19-555-2023 http://hdl.handle.net/21.11116/0000-000D-8BF8-F Climate of the Past info:eu-repo/semantics/article 2023 ftpubman https://doi.org/10.5194/cp-19-555-2023 2023-08-13T23:44:21Z The oxygen isotopic composition of benthic foraminiferal tests (δ18Ob) is one of the pre-eminent tools for correlating marine sediments and interpreting past terrestrial ice volume and deep-ocean temperatures. Despite the prevalence of δ18Ob applications to marine sediment cores over the Quaternary, its use is limited in the Arctic Ocean because of low benthic foraminiferal abundances, challenges with constructing independent sediment core age models, and an apparent muted amplitude of Arctic δ18Ob variability compared to open-ocean records. Here we evaluate the controls on Arctic δ18Ob by using ostracode paleothermometry to generate a composite record of the δ18O of seawater (δ18Osw) from 12 sediment cores in the intermediate to deep Arctic Ocean (700–2700 m) that covers the last 600 kyr based on biostratigraphy and orbitally tuned age models. Results show that Arctic δ18Ob was generally higher than open-ocean δ18Ob during interglacials but was generally equivalent to global reference records during glacial periods. The reduced glacial–interglacial Arctic δ18Ob range resulted in part from the opposing effect of temperature, with intermediate to deep Arctic warming during glacials counteracting the whole-ocean δ18Osw increase from expanded terrestrial ice sheets. After removing the temperature effect from δ18Ob, we find that the intermediate to deep Arctic experienced large (≥1 ‰) variations in local δ18Osw, with generally higher local δ18Osw during interglacials and lower δ18Osw during glacials. Both the magnitude and timing of low local δ18Osw intervals are inconsistent with the recent proposal of freshwater intervals in the Arctic Ocean during past glaciations. Instead, we suggest that lower local δ18Osw in the intermediate to deep Arctic Ocean during glaciations reflected weaker upper-ocean stratification and more efficient transport of low-δ18Osw Arctic surface waters to depth by mixing and/or brine rejection. Article in Journal/Newspaper Arctic Arctic Ocean Foraminifera* Max Planck Society: MPG.PuRe Arctic Arctic Ocean Climate of the Past 19 3 555 578 |
institution |
Open Polar |
collection |
Max Planck Society: MPG.PuRe |
op_collection_id |
ftpubman |
language |
English |
description |
The oxygen isotopic composition of benthic foraminiferal tests (δ18Ob) is one of the pre-eminent tools for correlating marine sediments and interpreting past terrestrial ice volume and deep-ocean temperatures. Despite the prevalence of δ18Ob applications to marine sediment cores over the Quaternary, its use is limited in the Arctic Ocean because of low benthic foraminiferal abundances, challenges with constructing independent sediment core age models, and an apparent muted amplitude of Arctic δ18Ob variability compared to open-ocean records. Here we evaluate the controls on Arctic δ18Ob by using ostracode paleothermometry to generate a composite record of the δ18O of seawater (δ18Osw) from 12 sediment cores in the intermediate to deep Arctic Ocean (700–2700 m) that covers the last 600 kyr based on biostratigraphy and orbitally tuned age models. Results show that Arctic δ18Ob was generally higher than open-ocean δ18Ob during interglacials but was generally equivalent to global reference records during glacial periods. The reduced glacial–interglacial Arctic δ18Ob range resulted in part from the opposing effect of temperature, with intermediate to deep Arctic warming during glacials counteracting the whole-ocean δ18Osw increase from expanded terrestrial ice sheets. After removing the temperature effect from δ18Ob, we find that the intermediate to deep Arctic experienced large (≥1 ‰) variations in local δ18Osw, with generally higher local δ18Osw during interglacials and lower δ18Osw during glacials. Both the magnitude and timing of low local δ18Osw intervals are inconsistent with the recent proposal of freshwater intervals in the Arctic Ocean during past glaciations. Instead, we suggest that lower local δ18Osw in the intermediate to deep Arctic Ocean during glaciations reflected weaker upper-ocean stratification and more efficient transport of low-δ18Osw Arctic surface waters to depth by mixing and/or brine rejection. |
format |
Article in Journal/Newspaper |
author |
Farmer, J. Keller, K. Poirier, R. Dwyer, G. Schaller, M. Coxall, H. O'Regan, M. Cronin, T. |
spellingShingle |
Farmer, J. Keller, K. Poirier, R. Dwyer, G. Schaller, M. Coxall, H. O'Regan, M. Cronin, T. A 600 kyr reconstruction of deep Arctic seawater δ 18 O from benthic foraminiferal δ 18 O and ostracode Mg ∕ Ca paleothermometry |
author_facet |
Farmer, J. Keller, K. Poirier, R. Dwyer, G. Schaller, M. Coxall, H. O'Regan, M. Cronin, T. |
author_sort |
Farmer, J. |
title |
A 600 kyr reconstruction of deep Arctic seawater δ 18 O from benthic foraminiferal δ 18 O and ostracode Mg ∕ Ca paleothermometry |
title_short |
A 600 kyr reconstruction of deep Arctic seawater δ 18 O from benthic foraminiferal δ 18 O and ostracode Mg ∕ Ca paleothermometry |
title_full |
A 600 kyr reconstruction of deep Arctic seawater δ 18 O from benthic foraminiferal δ 18 O and ostracode Mg ∕ Ca paleothermometry |
title_fullStr |
A 600 kyr reconstruction of deep Arctic seawater δ 18 O from benthic foraminiferal δ 18 O and ostracode Mg ∕ Ca paleothermometry |
title_full_unstemmed |
A 600 kyr reconstruction of deep Arctic seawater δ 18 O from benthic foraminiferal δ 18 O and ostracode Mg ∕ Ca paleothermometry |
title_sort |
600 kyr reconstruction of deep arctic seawater δ 18 o from benthic foraminiferal δ 18 o and ostracode mg ∕ ca paleothermometry |
publishDate |
2023 |
url |
http://hdl.handle.net/21.11116/0000-000D-8BF8-F |
geographic |
Arctic Arctic Ocean |
geographic_facet |
Arctic Arctic Ocean |
genre |
Arctic Arctic Ocean Foraminifera* |
genre_facet |
Arctic Arctic Ocean Foraminifera* |
op_source |
Climate of the Past |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.5194/cp-19-555-2023 http://hdl.handle.net/21.11116/0000-000D-8BF8-F |
op_doi |
https://doi.org/10.5194/cp-19-555-2023 |
container_title |
Climate of the Past |
container_volume |
19 |
container_issue |
3 |
container_start_page |
555 |
op_container_end_page |
578 |
_version_ |
1776197829552766976 |