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Saw-tooth pattern of North Atlantic current speed during Dansgaard-Oeschger cycles revealed by the magnetic grain size of Reykjanes Ridge sediments at 59 degrees N

Snowball, Ian LU and Moros, M (2003) In Paleoceanography 18(2).
Abstract
Detailed mineral (rock) magnetic measurements, including high-resolution magnetic hysteresis loops, were carried out on three sediment cores recovered from the Reykjanes Ridge in the North Atlantic. Supported by physical grain-size analyses, titanomagnetite grain-size variations form a proxy of the speed of near-bottom currents and reveal a cyclic ""saw-tooth'' pattern between Dansgaard-Oeschger cycles 8 and 5. The magnetic grain-size data suggest that these Dansgaard-Oeschger cycles were characterized by gradual intensification of the near-bottom current speed, while other paleoceanographic proxies indicate escalating iceberg discharge and declining sea surface temperatures. These observations are contrary to the frequently assumed and... (More)
Detailed mineral (rock) magnetic measurements, including high-resolution magnetic hysteresis loops, were carried out on three sediment cores recovered from the Reykjanes Ridge in the North Atlantic. Supported by physical grain-size analyses, titanomagnetite grain-size variations form a proxy of the speed of near-bottom currents and reveal a cyclic ""saw-tooth'' pattern between Dansgaard-Oeschger cycles 8 and 5. The magnetic grain-size data suggest that these Dansgaard-Oeschger cycles were characterized by gradual intensification of the near-bottom current speed, while other paleoceanographic proxies indicate escalating iceberg discharge and declining sea surface temperatures. These observations are contrary to the frequently assumed and strictly applied positive relationship between high-latitude warmth and North Atlantic Deep Water formation. Within the confines of temporal control, however, it would appear that peaks in iceberg discharge and slow near-bottom current speeds were synchronous. The magnetic hysteresis data also demonstrate that magnetic concentration parameters, such as magnetic susceptibility, do not necessarily provide direct evidence of paleocirculation. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
circulation, thermohaline, current speed, North Atlantic, magnetic grain-size, Dansgaard-Oeschger cycles
in
Paleoceanography
volume
18
issue
2
publisher
American Geophysical Union
external identifiers
  • wos:000182595700001
ISSN
0883-8305
DOI
10.1029/2001PA000732
language
English
LU publication?
yes
id
317d849d-9a25-4c57-897e-8e17ec2aa09e (old id 312436)
date added to LUP
2007-09-22 11:17:32
date last changed
2016-04-15 19:11:59
@article{317d849d-9a25-4c57-897e-8e17ec2aa09e,
  abstract     = {Detailed mineral (rock) magnetic measurements, including high-resolution magnetic hysteresis loops, were carried out on three sediment cores recovered from the Reykjanes Ridge in the North Atlantic. Supported by physical grain-size analyses, titanomagnetite grain-size variations form a proxy of the speed of near-bottom currents and reveal a cyclic ""saw-tooth'' pattern between Dansgaard-Oeschger cycles 8 and 5. The magnetic grain-size data suggest that these Dansgaard-Oeschger cycles were characterized by gradual intensification of the near-bottom current speed, while other paleoceanographic proxies indicate escalating iceberg discharge and declining sea surface temperatures. These observations are contrary to the frequently assumed and strictly applied positive relationship between high-latitude warmth and North Atlantic Deep Water formation. Within the confines of temporal control, however, it would appear that peaks in iceberg discharge and slow near-bottom current speeds were synchronous. The magnetic hysteresis data also demonstrate that magnetic concentration parameters, such as magnetic susceptibility, do not necessarily provide direct evidence of paleocirculation.},
  author       = {Snowball, Ian and Moros, M},
  issn         = {0883-8305},
  keyword      = {circulation,thermohaline,current speed,North Atlantic,magnetic grain-size,Dansgaard-Oeschger cycles},
  language     = {eng},
  number       = {2},
  publisher    = {American Geophysical Union},
  series       = {Paleoceanography},
  title        = {Saw-tooth pattern of North Atlantic current speed during Dansgaard-Oeschger cycles revealed by the magnetic grain size of Reykjanes Ridge sediments at 59 degrees N},
  url          = {http://dx.doi.org/10.1029/2001PA000732},
  volume       = {18},
  year         = {2003},
}