Fluegge, A. Alfred-Wegener-Institut, afluegge@awi-bremerhaven
Maassen, J. Sonderforschungsbereich 313, jmaassen@sfb313.uni-kiel.de
Schulz-Bull, D. E.. Institut fuer Meereskunde, dbull@ifm.uni-kiel.de
Suess, E. GEOMAR, esuess@geomar.de

 
REFINED TEMPERATURE CALIBRATION OF THE ALKENONE UNSATURATION RATIO FOR THE NORTHERN NORTH ATLANTIC
 
The ratio of di- to tetra-unsaturated C37 methyl ketones as defined in the alkenone unsaturation index (UK37=([C37:2]-[C37:4])/([C37:2]+[C37:3]+[C37:4]) and UK37'=[C37:2]/([C37:2]+[C37:3]) is a well established tool to estimate paleo sea surface temperatures. previous studies report high variations of the UK37 at growth temperatures below 5-8 degree Celsius restricting the application of this molecular paleo-thermometer in high latitude oceanic regions. In a comprehensive investigation, coretop sediments, sediment trap samples, and sea surface particulate matter from the northern North Atlantic were analyzed to correlate the alkenone unsaturation ratio with production temperature. Both, UK37 and the UK37' correlate linear with temperature in the range of 1-12 degree Celsius (R=0.95 and R=0.79, respectively). However, relative abundances of the di-unsaturated ketone scatters increasingly with decreasing growth temperature. This in addition to the low slope of the UK37' versus temperature relationship (0.021±0.002) results in uncertainties of temperature estimates that are significantly larger than those obtained with the UK37, which has a steeper slope (0.085±0.004). Therefore, our results suggest to use the UK37 instead of UK37' to estimate paleo sea surface temperatures for the northern North Atlantic.
 
Day: Thursday, Feb. 4
Time: Poster
Location: Sweeney Center
 
Code: SS36TH0649S