Global sediment core-top calibration of the TEX 86 paleothermometer in the ocean
Abstract
The TEX 86 (TetraEther indeX of tetraethers consisting of 86 carbon atoms) paleothermometer is based on the relative distribution of archaeal lipids, i.e. isoprenoid glycerol dibiphytanyl glycerol tetraethers (GDGTs), and is increasingly used to reconstruct past sea water temperatures. To establish a more extensive, global calibration of the TEX 86 paleothermometer, we analyzed GDGTs in 287 (in comparison with 44 in currently used calibration) core-top sediments distributed over the world oceans and deposited at different depths. Comparisons of TEX 86 data with (depth-weighted) annual mean temperatures of the overlying waters between 0 m and 4000 m as well as with different seasonal mean temperatures at 0 m water depth showed that the TEX 86 proxy reflects mostly annual mean temperatures of the upper mixed layer. The relationship between TEX 86 values and sea-surface temperatures (SSTs) was non-linear mainly because below 5 °C the change in TEX 86 values was minor with temperature. This suggests that the TEX 86 proxy might not be directly applicable for the Polar Oceans. Nevertheless, between 5 °C and 30 °C, the TEX 86 proxy has a strong linear relationship with SSTs. Here, we, therefore, propose a new linear calibration model ( T = -10.78 + 56.2 ∗ TEX 86, r2 = 0.935, n = 223) for past SST reconstructions using the TEX 86 palaeothermometer.
- Publication:
-
Geochimica et Cosmochimica Acta
- Pub Date:
- February 2008
- DOI:
- 10.1016/j.gca.2007.12.010
- Bibcode:
- 2008GeCoA..72.1154K