Western North Atlantic LGM and YD Radiocarbon and Stable Isotope Data
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                NOAA Paleoclimatology Program
                               and
         World Data Center for Paleoclimatology, Boulder
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NOTE: PLEASE CITE ORIGINAL REFERENCE WHEN USING THIS DATA!!!!!

NAME OF DATA SET: Western North Atlantic LGM and YD Radiocarbon and Stable Isotope Data
LAST UPDATE: 11/2004 (Original Receipt by WDC Paleo)


CONTRIBUTOR: Lloyd D. Keigwin, Woods Hole Oceanographic Institution,
IGBP PAGES/WDCA CONTRIBUTION SERIES NUMBER: 2004-080


SUGGESTED DATA CITATION: Keigwin, L.D.  2004.
Western North Atlantic LGM and YD Radiocarbon and Stable Isotope Data.
IGBP PAGES/World Data Center for Paleoclimatology 
Data Contribution Series #2004-080. 
NOAA/NGDC Paleoclimatology Program, Boulder CO, USA. 


ORIGINAL REFERENCE: Keigwin, L.D.  2004.
Radiocarbon and stable isotope constraints on Last Glacial Maximum 
and Younger Dryas ventilation in the western North Atlantic.
Paleoceanography, Vol. 19, PA4012, doi:10.1029/2004PA001029.


ABSTRACT:
Foraminiferal abundance, 14C ventilation ages, and stable isotope ratios 
in cores from high deposition rate locations in the western subtropical 
North Atlantic are used to infer changes in ocean and climate during the
Younger Dryas (YD) and Last Glacial Maximum (LGM). The d18O of the surface 
dwelling planktonic foram Globigerinoides ruber records the present-day 
decrease in surface temperature (SST) of ~4C from Gulf Stream waters to 
the northeastern Bermuda Rise. If during the LGM the modern d18O/salinity 
relationship was maintained, this SST contrast was reduced to 2C. With LGM 
to interglacial d18O changes of at least 2.2 per mil, SSTs in the western 
subtropical gyre may have been as much as 5C colder. Above ~2.3 km, glacial 
d13C was higher than today, consistent with nutrient-depleted (younger) 
bottom waters, as identified previously. Below that, d13C decreased 
continually to -0.5 per mil, about equal to the lowest LGM d13C in the 
North Pacific Ocean. Seven pairs of benthic and planktonic foraminiferal 
14C dates from cores >2.5 km deep differ by 1100 ±340 years, with a maximum 
apparent ventilation age of ~1500 years at 4250 m and at ~4700 m. Apparent 
ventilation ages are presently unavailable for the LGM < 2.5 km because of 
problems with reworking on the continental slope when sea level was low. 
Because LGM d13C is about the same in the deep North Atlantic and the deep 
North Pacific, and because the oldest apparent ventilation ages in the 
LGM North Atlantic are the same as the North Pacific today, it is possible 
that the same water mass, probably of southern origin, flowed deep within 
each basin during the LGM. Very early in the YD, dated here at 11.25 ± 0.25 
(n = 10) conventional 14C kyr BP (equal to 12.9 calendar kyr BP), apparent 
ventilation ages <2.3 km water depth were about the same as North Atlantic 
Deep Water today. Below ~2.3 km, four YD pairs average 1030 ± 400 years. 
The oldest apparent ventilation age for the YD is 1600 years at 4250 m. 
This strong contrast in ventilation, which indicates a front between water 
masses of very different origin, is similar to glacial profiles of 
nutrient-like proxies. This suggests that the LGM and YD modes of ocean 
circulation were the same.


GEOGRAPHIC REGION: western subtropical North Atlantic 
PERIOD OF RECORD: 22 KYrBP - present
FUNDING SOURCE:  National Science Foundation, USA.


  
DESCRIPTION:
Faunal, Carbonate, and stable isotope data from 21 high deposition rate 
sediment cores in the western subtropical North Atlantic, used to infer 
changes in ocean and climate during the Younger Dryas (YD) and 
Last Glacial Maximum (LGM).