noaa-ocean-12524
Southern Ocean Eocene-Oligocene Foraminiferal d18O and Mg/Ca Data
Bohaty, S.M.; Zachos, J.C.; Delaney, M.L.
Southern Ocean Eocene-Oligocene Foraminiferal d18O and Mg/Ca Data
2012-02-15
NCDC-Paleoclimatology
ONLINE Files
Pending
https://www.ncdc.noaa.gov/paleo/study/12524
Investigator
S.M.
Bohaty
Investigator
J.C.
Zachos
Investigator
M.L.
Delaney
earth science
paleoclimate
paleoceanography
delta 18O,foraminifer,null,per mil,null,paleoceanography,null,null,N,S. angiporoides and Cibicidoides sp.
earth science
paleoclimate
paleoceanography
depth at sample start,null,null,centimeter,null,paleoceanography,null,null,N,null
earth science
paleoclimate
paleoceanography
age,null,null,million years ago,null,paleoceanography,null,null,N,null
earth science
paleoclimate
paleoceanography
manganese/calcium,foraminifer,null,dimensionless,null,paleoceanography,null,null,N,S. angiporoides and Cibicidoides sp.
earth science
paleoclimate
paleoceanography
depth at sample end,null,null,centimeter,null,paleoceanography,null,null,N,null
earth science
paleoclimate
paleoceanography
depth,null,null,meter,null,paleoceanography,null,null,N,mbsf
earth science
paleoclimate
paleoceanography
magnesium/calcium,foraminifer,null,dimensionless,null,paleoceanography,null,null,N,S. angiporoides and Cibicidoides sp.
earth science
paleoclimate
paleocean
geochemistry
earth science
paleoclimate
paleocean
oxygen isotopes
geoscientificInformation
34998000 cal yr BP
32501000 cal yr BP
Complete
-64.517
-58.441
3.0999
82.7878
-2307
-1290
Ocean
Southern Ocean
ODP744>LATITUDE -61.6>LONGITUDE 80.6
Ocean
Southern Ocean
ODP 738B>LATITUDE -62.709>LONGITUDE 82.7878
Ocean
Southern Ocean
ODP 689B>LATITUDE -64.517>LONGITUDE 3.0999
Ocean
Southern Ocean
ODP748>LATITUDE -58.441>LONGITUDE 78.9981
None
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English
DOC/NOAA/NESDIS/NCEI
National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce
https://www.ncdc.noaa.gov/data-access/paleoclimatology-data
DATA Center Contact
Bruce
Bauer
bruce.a.bauer@noaa.gov
paleo@noaa.gov
303-497-6280
303-497-6513
325 Broadway, E/NE31
Boulder
CO
80305-3328
USA
online
ASCII
Bohaty, S.M., J.C. Zachos, and M.L. Delaney. 2012.
Foraminiferal Mg/Ca evidence for Southern Ocean cooling
across the Eocene-Oligocene transition.
Earth and Planetary Science Letters, Vols. 317-318, pp. 251-261,
1 February 2012. doi:10.1016/j.epsl.2011.11.037.
Constraining the magnitude of high-latitude temperature change
across the Eocene-Oligocene transition (EOT) is essential for
quantifying the magnitude of Antarctic ice-sheet expansion
and understanding regional climate response to this event.
To this end, we constructed high-resolution stable oxygen
isotope (d18O) and magnesium/calcium (Mg/Ca) records from
planktic and benthic foraminifera at four Ocean Drilling Program
(ODP) sites in the Southern Ocean. Planktic foraminiferal Mg/Ca
records from the Kerguelen Plateau (ODP Sites 738, 744, and 748)
show a consistent pattern of temperature change, indicating 2-3°C
cooling in direct conjunction with the first step of a two-step
increase in benthic and planktic foraminiferal d18O values across
the EOT. In contrast, benthic Mg/Ca records from Maud Rise
(ODP Site 689) and the Kerguelen Plateau (ODP Site 748) do not
exhibit significant temperature change. The contrasting temperature
histories derived from the planktic and benthic Mg/Ca records
are not reconcilable, since vertical d18O gradients remained
nearly constant at all sites between 35.0 and 32.5 Ma. Based on
the coherency of the planktic Mg/Ca records from the Kerguelen
Plateau sites and complications with benthic Mg/Ca paleothermometry
at low temperatures, the planktic Mg/Ca records are deemed the most
reliable measure of Southern Ocean temperature change. We therefore
interpret a uniform cooling of 2-3 °C in both deep surface
(thermocline) waters and intermediate deep waters of the Southern
Ocean across the EOT. Cooling of Southern Ocean surface waters
across the EOT was likely propagated to the deep ocean, since deep
waters were primarily sourced on the Antarctic margin throughout
this time interval. Removal of the temperature component from the
observed foraminiferal d18O shift indicates that seawater d18O values
increased by 0.6±0.15‰ across the EOT interval, corresponding to
an increase in global ice volume to a level equivalent with 60–130%
modern East Antarctic ice sheet volume.
STUDY NOTES: High-resolution stable oxygen isotope (d18O) and magnesium/calcium
(Mg/Ca) records from planktic and benthic foraminifera at four
Ocean Drilling Program (ODP) sites in the Southern Ocean covering
the Eocene-Oligocene transition (EOT), ~35 - 32 Ma.
GET DATA
https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/bohaty2012/bohaty2012.xls
GET DATA
https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/bohaty2012/bohaty2012.txt
USA/NOAA
DIF
Version 9.8.4
2018-12-11
2018-12-11