Geochemical characteristics of lake clay drilled in well QZ-4: its implication for geochemical response to climate change in the central Tibetan Plateau in the Middle-Late Pleistocene

A colour sequence, which is composed of a yellow subsequence in the lower unit and a grey subsequence in the upper unit, is an important climate archive for the central Tibetan Plateau in the Middle-Late Pleistocene. However, little study has been done on it. In well QZ-4, this colour sequence is thicker than 116 m, which is an important climate archive for the central Tibetan Plateau in the Middle-Late Pleistocene. In this work, the ESR dating and geochemistry analysis have been carried out to provide a preliminary insight into the paleo-climate change in the central Tibetan Plateau. It can be concluded that the 23.56 ka (125.96-149.52 ka BP) time interval, which is marked by the angular unconformity surface at 272.48 m in depth, proves that the deposition of this colour sequence is dominated by Gonghe Movement. After this movement, chemical weathering is reduced; however, the sedimentation rate is increased from 0.18 to 3.5 m/ka. In the central Tibetan Plateau, the climate became colder and drier in the Middle-Late Pleistocene, which is roughly consistent with global paleo-climate change at that time. All these changes are correlated with the change of elevation and atmospheric circulation in the Tibetan Plateau and its surrounding area, which are driven by the tectonic uplift of Gonghe Movement. The Gonghe Movement is likely a driving force for the short-lived spike at about 120 ka.