Reconstruction of hydrographic changes in the southern Norwegian Sea during the past 135 kyr and the impact of different foraminiferal Mg/Ca cleaning protocols
The shallow subsurface hydrography in the southern Norwegian Sea during the past 135,000 years was investigated using parallel measurements of Mg/Ca and δ18O in shells of the planktic foraminiferal species Neogloboquadrina pachyderma. Two cleaning methods were applied prior to Mg/Ca analysis, “Mg cl...
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Language: | English |
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American Geophysical Union
2016
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Online Access: | https://hdl.handle.net/10037/10583 https://doi.org/10.1002/2016GC006325 |
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ftunivtroemsoe:oai:munin.uit.no:10037/10583 2023-05-15T14:27:58+02:00 Reconstruction of hydrographic changes in the southern Norwegian Sea during the past 135 kyr and the impact of different foraminiferal Mg/Ca cleaning protocols Ezat, Mohamed Rasmussen, Tine Lander Groeneveld, Jeroen 2016-08-20 https://hdl.handle.net/10037/10583 https://doi.org/10.1002/2016GC006325 eng eng American Geophysical Union Ezat, M.M. (2015). North Atlantic–Norwegian Sea exchanges during the past 135,000 years: Evidence from foraminiferal ∆ 14 C, δ 11 B, δ 18 O, δ 13 C, Mg/Ca, and Cd/Ca. (Doctoral thesis). https://hdl.handle.net/10037/24869 . Geochemistry Geophysics Geosystems info:eu-repo/grantAgreement/RCN/SFF/223259/Norway/Centre for Arctic Gas Hydrate, Environment and Climate/CAGE Ezat, M. M., T. L. Rasmussen, and J. Groeneveld (2016), Reconstruction of hydrographic changes in the southern Norwegian Sea during the past 135 kyr and the impact of different foraminiferal Mg/Ca cleaning protocols, Geochem. Geophys. Geosyst., 17, 3420–3436, doi:10.1002/2016GC006325. FRIDAID 1371978 doi:10.1002/2016GC006325 1525-2027 https://hdl.handle.net/10037/10583 openAccess VDP::Matematikk og Naturvitenskap: 400::Geofag: 450 VDP::Mathematics and natural science: 400::Geosciences: 450 Journal article Tidsskriftartikkel Peer reviewed 2016 ftunivtroemsoe https://doi.org/10.1002/2016GC006325 2022-04-27T22:58:30Z The shallow subsurface hydrography in the southern Norwegian Sea during the past 135,000 years was investigated using parallel measurements of Mg/Ca and δ18O in shells of the planktic foraminiferal species Neogloboquadrina pachyderma. Two cleaning methods were applied prior to Mg/Ca analysis, “Mg cleaning” and “full cleaning” methods. Different results were obtained, which are most likely due to a more efficient removal of Mn-contaminant coatings of the shells, when the “full cleaning” procedure was applied. We further combined Mg/Ca and B/Ca from the “full cleaning” method with δ18O values to constrain the calcification temperature and seawater-δ18O (δ18Osw) in the past. During Heinrich Stadial (HS)1 (∼18.5–15 ka) N. pachyderma constituted >80% of the planktic foraminiferal population, δ18Osw decreased by ∼1.5‰, and shallow subsurface temperature increased by ∼1.5–3°C, suggesting strong stratification in the upper water column and a possible subsurface inflow of Atlantic water below a well-developed halocline during the calcification seasons of N. pachyderma. Similar decreases in δ18Osw are also recorded for other Heinrich stadials (HS2, 3, 4, 6, and 11). Our temperature estimates confirm previous observations of the delay of the last interglacial “Eemian” warm peak in the eastern Nordic Seas compared to the North Atlantic, and a late warming coinciding with the summer insolation minimum at 60°N. In addition, relatively high values of δ18Osw during the early Eemian suggest a shallow subsurface inflow of Atlantic water below a thin layer of Arctic surface water. Article in Journal/Newspaper Arctic Arctic Foraminifera* Neogloboquadrina pachyderma Nordic Seas North Atlantic Norwegian Sea University of Tromsø: Munin Open Research Archive Arctic Norwegian Sea Geochemistry, Geophysics, Geosystems 17 8 3420 3436 |
institution |
Open Polar |
collection |
University of Tromsø: Munin Open Research Archive |
op_collection_id |
ftunivtroemsoe |
language |
English |
topic |
VDP::Matematikk og Naturvitenskap: 400::Geofag: 450 VDP::Mathematics and natural science: 400::Geosciences: 450 |
spellingShingle |
VDP::Matematikk og Naturvitenskap: 400::Geofag: 450 VDP::Mathematics and natural science: 400::Geosciences: 450 Ezat, Mohamed Rasmussen, Tine Lander Groeneveld, Jeroen Reconstruction of hydrographic changes in the southern Norwegian Sea during the past 135 kyr and the impact of different foraminiferal Mg/Ca cleaning protocols |
topic_facet |
VDP::Matematikk og Naturvitenskap: 400::Geofag: 450 VDP::Mathematics and natural science: 400::Geosciences: 450 |
description |
The shallow subsurface hydrography in the southern Norwegian Sea during the past 135,000 years was investigated using parallel measurements of Mg/Ca and δ18O in shells of the planktic foraminiferal species Neogloboquadrina pachyderma. Two cleaning methods were applied prior to Mg/Ca analysis, “Mg cleaning” and “full cleaning” methods. Different results were obtained, which are most likely due to a more efficient removal of Mn-contaminant coatings of the shells, when the “full cleaning” procedure was applied. We further combined Mg/Ca and B/Ca from the “full cleaning” method with δ18O values to constrain the calcification temperature and seawater-δ18O (δ18Osw) in the past. During Heinrich Stadial (HS)1 (∼18.5–15 ka) N. pachyderma constituted >80% of the planktic foraminiferal population, δ18Osw decreased by ∼1.5‰, and shallow subsurface temperature increased by ∼1.5–3°C, suggesting strong stratification in the upper water column and a possible subsurface inflow of Atlantic water below a well-developed halocline during the calcification seasons of N. pachyderma. Similar decreases in δ18Osw are also recorded for other Heinrich stadials (HS2, 3, 4, 6, and 11). Our temperature estimates confirm previous observations of the delay of the last interglacial “Eemian” warm peak in the eastern Nordic Seas compared to the North Atlantic, and a late warming coinciding with the summer insolation minimum at 60°N. In addition, relatively high values of δ18Osw during the early Eemian suggest a shallow subsurface inflow of Atlantic water below a thin layer of Arctic surface water. |
format |
Article in Journal/Newspaper |
author |
Ezat, Mohamed Rasmussen, Tine Lander Groeneveld, Jeroen |
author_facet |
Ezat, Mohamed Rasmussen, Tine Lander Groeneveld, Jeroen |
author_sort |
Ezat, Mohamed |
title |
Reconstruction of hydrographic changes in the southern Norwegian Sea during the past 135 kyr and the impact of different foraminiferal Mg/Ca cleaning protocols |
title_short |
Reconstruction of hydrographic changes in the southern Norwegian Sea during the past 135 kyr and the impact of different foraminiferal Mg/Ca cleaning protocols |
title_full |
Reconstruction of hydrographic changes in the southern Norwegian Sea during the past 135 kyr and the impact of different foraminiferal Mg/Ca cleaning protocols |
title_fullStr |
Reconstruction of hydrographic changes in the southern Norwegian Sea during the past 135 kyr and the impact of different foraminiferal Mg/Ca cleaning protocols |
title_full_unstemmed |
Reconstruction of hydrographic changes in the southern Norwegian Sea during the past 135 kyr and the impact of different foraminiferal Mg/Ca cleaning protocols |
title_sort |
reconstruction of hydrographic changes in the southern norwegian sea during the past 135 kyr and the impact of different foraminiferal mg/ca cleaning protocols |
publisher |
American Geophysical Union |
publishDate |
2016 |
url |
https://hdl.handle.net/10037/10583 https://doi.org/10.1002/2016GC006325 |
geographic |
Arctic Norwegian Sea |
geographic_facet |
Arctic Norwegian Sea |
genre |
Arctic Arctic Foraminifera* Neogloboquadrina pachyderma Nordic Seas North Atlantic Norwegian Sea |
genre_facet |
Arctic Arctic Foraminifera* Neogloboquadrina pachyderma Nordic Seas North Atlantic Norwegian Sea |
op_relation |
Ezat, M.M. (2015). North Atlantic–Norwegian Sea exchanges during the past 135,000 years: Evidence from foraminiferal ∆ 14 C, δ 11 B, δ 18 O, δ 13 C, Mg/Ca, and Cd/Ca. (Doctoral thesis). https://hdl.handle.net/10037/24869 . Geochemistry Geophysics Geosystems info:eu-repo/grantAgreement/RCN/SFF/223259/Norway/Centre for Arctic Gas Hydrate, Environment and Climate/CAGE Ezat, M. M., T. L. Rasmussen, and J. Groeneveld (2016), Reconstruction of hydrographic changes in the southern Norwegian Sea during the past 135 kyr and the impact of different foraminiferal Mg/Ca cleaning protocols, Geochem. Geophys. Geosyst., 17, 3420–3436, doi:10.1002/2016GC006325. FRIDAID 1371978 doi:10.1002/2016GC006325 1525-2027 https://hdl.handle.net/10037/10583 |
op_rights |
openAccess |
op_doi |
https://doi.org/10.1002/2016GC006325 |
container_title |
Geochemistry, Geophysics, Geosystems |
container_volume |
17 |
container_issue |
8 |
container_start_page |
3420 |
op_container_end_page |
3436 |
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1766302076009185280 |