Altitudinal shifts in the branched tetraether lipid distribution in soil from Mt. Kilimanjaro (Tanzania): Implications for the MBT/CBT continental palaeothermometer

The distribution of branched glycerol dialkyl glycerol tetraether (GDGT) lipids in sixteen soil samples from an altitudinal transect on the southeastern slope of Mt. Kilimanjaro (Tanzania) was examined. The degree of methylation and cyclisation (expressed in the so-called MBT and CBT indices) of these GDGTs, derived from unknown soil bacteria, was determined mainly by changes in mean annual air temperature (MAT). Application of the global soil correlation [Weijers, J.W.H., Schouten, S., van den Donker, J.C., Hopmans, E.C., Sinninghe Damsté, J.S., 2007. Environmental controls on bacterial tetraether membrane lipid distribution in soils. Geochimica et Cosmochimica Acta 71, 703–713] resulted in reconstructed MATs slightly higher than reported in situ values. The findings support the application of the MBT/CBT continental palaeothermometer.