Temperature changes reconstructed from branched GDGTs on the central Loess Plateau during the past 130–5 ka

Abstract

This study investigated the glycerol dialkyl glycerol tetraethers (GDGTs) in a loess-paleosol sequence (LPS) to quantitatively reconstruct the mean annual air temperature (MAT) on the central Chinese Loess Plateau (CLP) during the past 130–5 ka. The results show that: (1) MAT variations reconstructed by global MBT (methylation index of branched tetraethers) and CBT (cyclisation ratio of branched tetraethers) transfer functions at Xifeng range from 7.3 °C to 28.4 °C. The MAT variation on the central CLP (Xifeng site) is between the previously reported MAT variations on the western (Yuanbao site) and eastern CLP (Mangshan site), in agreement with the pattern that temperature increases from the northwestern CLP to the southeastern CLP. (2) MAT variations estimated by transfer functions of global MBT-CBT, global MBT′-CBT and Chinese MBT-CBT for LPS are nearly all higher than the modern MAT at Xifeng, indicating that the reconstructed MAT values are probably overestimated. (3) The maximum value of magnetic susceptibility at Xifeng lagged that of the MAT derived by MBT-CBT proxy during the last interglacial (∼9 ka lag) and since the last deglacial (∼6 ka lag).