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The Faroe-Shetland Gateway: Late Quaternary water mass exchange between the Nordic seas and the northeastern Atlantic

Rasmussen, Tine LU ; Backstrom, D; Heinemeier, J; Klitgaard-Kristensen, D; Knutz, PC; Kuijpers, A; Lassen, S; Thomsen, E; Troelstra, SR and van Weering, TCE (2002) In Marine Geology 188(1-2). p.165-192
Abstract
Thirteen piston and gravity cores from the Faroe-Shetland area were investigated for their planktic and benthic foraminiferal and oxygen isotopic distributions. Eight time-slices between 18 ka BP and the present were reconstructed to study variations in surface and deep water exchange between the SE Norwegian Sea and the northeast Atlantic Ocean. Today, a relatively strong northward flow of warm North Atlantic surface water is counterbalanced by a southward outflow of newly convected cold bottom water, the Norwegian Sea Overflow Water. During the last glacial maximum at 18 ka BP both the surface and bottom flows were slow and the climate conditions were Arctic. The convection north of the Faroe area was weak and unstable. The first... (More)
Thirteen piston and gravity cores from the Faroe-Shetland area were investigated for their planktic and benthic foraminiferal and oxygen isotopic distributions. Eight time-slices between 18 ka BP and the present were reconstructed to study variations in surface and deep water exchange between the SE Norwegian Sea and the northeast Atlantic Ocean. Today, a relatively strong northward flow of warm North Atlantic surface water is counterbalanced by a southward outflow of newly convected cold bottom water, the Norwegian Sea Overflow Water. During the last glacial maximum at 18 ka BP both the surface and bottom flows were slow and the climate conditions were Arctic. The convection north of the Faroe area was weak and unstable. The first indication of the deglaciation is a decrease in the planktic oxygen isotope values discernible southwest of the Faroe Islands at 15.5 ka BP. The deglaciation proceeded northeast and eastward synchronous with a gradual intensification of northward flowing warmer Atlantic Intermediate Water along the sea bottom. Meltwater fluxes increased between 14 and 13 ka BP producing cold surface waters, and the climatic cooling was extreme. There was no southward overflow of cold bottom water during this time period and the exchange of water masses between the Nordic seas and the North Atlantic Ocean was essentially reversed, i.e. estuarine. During the Bolling Interstadial at 12.5 ka BP northward flowing warm surface water was present to the east of the Faroe-Shetland Channel, wedged below a tongue of polar water spreading from the northwest and reaching into the Faroe-Shetland Channel. Convection in the Nordic seas and overflow of cold deep water started during the Bolling Interstadial. The polar water spread more eastward and southward during the following cold spell, the Younger Dryas, around 10.3 ka BP. The polar water was overlying the warmer, but more saline Atlantic water, which flowed northward below the cold surface water. The overflow of cold bottom water was supposedly only slightly weaker than during the Bolling Interstadial. Strong inflow of warm surface water took place during the Early Holocene at 9.5 ka BP and relatively dense cold water flowed southward along the bottom. The rate of water mass exchange reached a maximum at 6.5 ka BP, when both the inflow of warm Atlantic surface water and the outflow of cold dense bottom water appear to have been stronger than today. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
thermohaline circulation, foraminifera, Late Quaternary, North Atlantic, Faroe-Shetland Channel
in
Marine Geology
volume
188
issue
1-2
pages
165 - 192
publisher
Elsevier
external identifiers
  • wos:000178440100010
  • scopus:0037102516
ISSN
0025-3227
DOI
10.1016/S0025-3227(02)00280-3
language
English
LU publication?
yes
id
8b2155cc-c960-443a-b011-6620b0f6ee85 (old id 326004)
date added to LUP
2007-11-09 08:15:41
date last changed
2017-08-27 05:35:12
@article{8b2155cc-c960-443a-b011-6620b0f6ee85,
  abstract     = {Thirteen piston and gravity cores from the Faroe-Shetland area were investigated for their planktic and benthic foraminiferal and oxygen isotopic distributions. Eight time-slices between 18 ka BP and the present were reconstructed to study variations in surface and deep water exchange between the SE Norwegian Sea and the northeast Atlantic Ocean. Today, a relatively strong northward flow of warm North Atlantic surface water is counterbalanced by a southward outflow of newly convected cold bottom water, the Norwegian Sea Overflow Water. During the last glacial maximum at 18 ka BP both the surface and bottom flows were slow and the climate conditions were Arctic. The convection north of the Faroe area was weak and unstable. The first indication of the deglaciation is a decrease in the planktic oxygen isotope values discernible southwest of the Faroe Islands at 15.5 ka BP. The deglaciation proceeded northeast and eastward synchronous with a gradual intensification of northward flowing warmer Atlantic Intermediate Water along the sea bottom. Meltwater fluxes increased between 14 and 13 ka BP producing cold surface waters, and the climatic cooling was extreme. There was no southward overflow of cold bottom water during this time period and the exchange of water masses between the Nordic seas and the North Atlantic Ocean was essentially reversed, i.e. estuarine. During the Bolling Interstadial at 12.5 ka BP northward flowing warm surface water was present to the east of the Faroe-Shetland Channel, wedged below a tongue of polar water spreading from the northwest and reaching into the Faroe-Shetland Channel. Convection in the Nordic seas and overflow of cold deep water started during the Bolling Interstadial. The polar water spread more eastward and southward during the following cold spell, the Younger Dryas, around 10.3 ka BP. The polar water was overlying the warmer, but more saline Atlantic water, which flowed northward below the cold surface water. The overflow of cold bottom water was supposedly only slightly weaker than during the Bolling Interstadial. Strong inflow of warm surface water took place during the Early Holocene at 9.5 ka BP and relatively dense cold water flowed southward along the bottom. The rate of water mass exchange reached a maximum at 6.5 ka BP, when both the inflow of warm Atlantic surface water and the outflow of cold dense bottom water appear to have been stronger than today.},
  author       = {Rasmussen, Tine and Backstrom, D and Heinemeier, J and Klitgaard-Kristensen, D and Knutz, PC and Kuijpers, A and Lassen, S and Thomsen, E and Troelstra, SR and van Weering, TCE},
  issn         = {0025-3227},
  keyword      = {thermohaline circulation,foraminifera,Late Quaternary,North Atlantic,Faroe-Shetland Channel},
  language     = {eng},
  number       = {1-2},
  pages        = {165--192},
  publisher    = {Elsevier},
  series       = {Marine Geology},
  title        = {The Faroe-Shetland Gateway: Late Quaternary water mass exchange between the Nordic seas and the northeastern Atlantic},
  url          = {http://dx.doi.org/10.1016/S0025-3227(02)00280-3},
  volume       = {188},
  year         = {2002},
}