Calibration of the alkenone paleotemperature index U super(K) sub(3) super(') sub(7) based on core-tops from the eastern South Atlantic and the global ocean (60 degree N-60 degree S)

• Published in: Geochimica et cosmochimica acta 1998-01, Vol.62 (10), p.1757-1772
• Main Authors: Mueller, P J, Kirst, G, Ruhland, G, von Storch, I, Rosell-Mele, A
• Format: Article
• Language: English
• Subjects: Marine
• ISSN: 0016-7037
• DOI: 10.1016/S0016-7037(98)00097-0

We have analysed alkenones in 149 surface sediments from the eastern South Atlantic in order to establish a sediment-based calibration of the U super(K) sub(3) super(') sub(7) paleotemperature index. Our study covers the major tropical to subpolar production systems and sea-surface temperatures (SST's) between 0 degree and 27 degree C. In order to define the most suitable calibration for this region, the U super(K) sub(3) super(') sub(7) values were correlated to seasonal, annual, and production-weighted annual mean atlas temperatures and compared to previously published culture and core-top calibrations. The best linear correlation between U super(K) sub(3) super(') sub(7) and SST was obtained using annual mean SST from 0 to 10 m water depth (U super(K) sub(3) super(') sub(7) = 0.033 T + 0.069, r super(2) = 0.981). Data scattering increased significantly using temperatures of waters deeper than 20 m, suggesting that U super(K) sub(3) super(') sub(7) reflects mixed-layer SST and that alkenone production at thermocline depths was not high enough to significantly bias the mixed-layer signal. Regressions based on both production-weighted and on actual annual mean atlas SST were virtually identical, indicating that regional variations in the seasonality of primary production have no discernible effect on the U super(K) sub(3) super(') sub(7) vs.