A study of the alkenone, TEX86, and planktonic foraminifera in the Benguela Upwelling System: Implications for past sea surface temperature estimates

Suspended particulate matter from seawater and core top sediments were collected during 2003 Meteor cruise M57/1 in January-February from the continental margin off western South Africa for analysis of alkenones, glycerol dibiphytanyl glycerol tetraether (GDGT) lipids, and planktonic foraminifera. Alkenone analysis of suspended particulates in seawater and core top sediments indicates that U-37(K') temperatures were representative of annual mean sea surface temperature. In contrast, GDGT analysis suggests that TEX86 temperatures are cold-biased due to upward transports of GDGTs produced below the mixed layer. The analysis of plankton tow samples revealed that the d(18)O of Globorotalia inflata in core top sediments could be biased toward lower temperatures due to subsurface calcification. Accordingly, our study shows that each paleotemperature proxy may record different temperature signals in the Benguela upwelling system emphasizing the general need to constrain potential biases in each proxy for better interpreting paleoclimate records.