| Summary: | International audience The TEX86 (TetraEther indeX of tetraethers consisting of 86 carbon atoms, Schouten et al., 2002) paleothermometer was proposed based on the relative distribution of thaumarchaeotal lipids, i.e. isoprenoid glycerol dibiphytanyl glycerol tetraethers (GDGTs), and has been increasingly used to reconstruct past sea surface temperatures (SSTs). However, it appears that the TEX86 proxy might not be directly applicable for the polar oceans (Kim et al., 2008) and the use of a modified version of TEX86 with a logarithmic function which does not include the crenarchaeol regio-isomer (i.e. TEX86-L) seems to be a better option to reconstruct paleotemperatures in the Polar Oceans (Kim et al., 2010). More recently, a new calibration of TEX86-L with depth-integrated annual mean temperatures from 0 to 200 m water depth was also introduced with the calibration error of ±2.8°C (Kim et al., 2012), since Thaumarchaeota are in low abundance in the Antarctic summer surface water (the ~0-45 m layer of low salinity water mass) but more abundant in winter in a ~45-105 m interval of cold, salty water (i.e. the summer remnant of the previous winter, surface-mixed layer) (Kalanetra et al., 2009). We applied the TEX86-L proxy and its 0-200 m calibration model on piston core MD03-2601 (66°03.07S; 138°33.43E; 746 m water depth) recovered from the eastern Antarctic continental margin and jumbo piston core 10 (JPC-10, 64°53'S, 64°12'W, 905 m water depth) obtained from the western Antarctic Peninsula. We also analyzed 19 sediment samples of ODP 1098 (64°51'S, 64°12'W, 1010 m water depth) drilled at the JPC-10 site for comparison with the record of Shevenell et al. (2011). The application of the TEX86-L on most recent sediments at core sites MD03-2601 and JPC-10 resulted in +4.0°C and +1.2°C temperature estimates, respectively, within the range reasonable of the present annual mean 0-200 m temperature at core sites considering the calibration error. TEX86-L-derived temperatures varied between +0°C and +4°C for the ...
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