HR: 08:00h
AN: PP41A-01    [PDF]
TI: A high-resolution 25 ka sea-surface temperature record from the NW Atlantic Ocean: foraminiferal Mg/Ca compared to $\delta^{18}$O and sediment parameters.
AU: * Rashid, H
EM: hrashid@mit.edu
AF: Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139 United States
AU: Boyle, E A
EM: eaboyle@mit.edu
AF: Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139 United States
AU: Keigwin, L D
EM: lkeigwin@whoi.edu
AF: Woods Hole Oceanographic Institution, 93 Water Street, Woods Hole, MA 02543 United States
AB: We have measured the Mg/Ca ratio in planktonic foraminifera {\it Neogloboquadrina pachyderma}(sinistral), {\it Globigerina bulloides} and {\it Globigerina ruber} (white variety) in two North Atlantic cores. A modified version of the Boyle and Keigwin (1985/6) cleaning technique was employed (removing cemented clays, metal oxides and organic matter). Mg/Ca ratios within the Heinrich layers in the Labrador Sea (Hu90013-29; $58.2361\deg$N, $56.4576\deg$W; 2918m) vary from 0.30 to 1.25 mmol/mol measured mainly in the {\it N. pachyderma} (s.). In core CHN82-20PC ($43.3\deg$N, $29.5\deg$W; 3020 m) in the open North Atlantic Mg/Ca ranges from 0.67 to 1.20 mmol/mol (in {\it G. bulloides} and white {\it G. ruber} ). {\it G. bulloides } and {\it G. ruber} Mg/Ca were offset even when allowing for potential species calibration differences, in a sense that is consistent with the $\delta^{18}$O offset between these species. For calibration of Mg/Ca to temperature, we applied the Nrnberg (1995) calibration for {\it N. pachyderma} (s.), the Mashihotta {\it et al.} (2000) calibration method for {\it G. bulloides}, and the Lea {\it et al.} (2000) method for {\it G. ruber}. These results suggest fluctuations in sea-surface temperature (SST) between -2 and $10\deg$C during the deposition of Heinrich layers in the Labrador Sea. A $~6\deg$C cooling in SST was observed between the initiation and cessation of Heinrich layer 1 at CHN82-20 core site. However, SST rose as much as $8\deg$C during the Bolling-Allerod and fell $~4\deg$C during the Younger Dryas.
DE: 3339 Ocean/atmosphere interactions (0312, 4504)
DE: 3344 Paleoclimatology
DE: 4267 Paleoceanography
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting