Magnetic Properties of the Ganzi Loess and Their Implications for Precipitation History in the Eastern Tibetan Plateau Since the Last Interglacial

Abstract

AbstractLoess sequences in the eastern Tibetan Plateau (TP) are valuable paleoenvironmental archives for reconstructing the environmental history related to the Indian summer monsoon (ISM). We conducted a detailed environmental magnetism analysis of the Ganzi loess sequence that developed since the Last Interglacial (LIG) and reconstructed the paleo‐precipitation history by analyzing multiple magnetic parameters. Our results are as follows: (a) Magnetic minerals of the Ganzi loess are mainly maghemite and magnetite, with high concentrations of magnetic minerals in the paleosol layer. The pedogenic ferrimagnetic particles dominated the magnetic enhancement, and magnetic parameters can be used to reconstruct precipitation history. (b) Precipitation reconstructed by using the multiple magnetic parameters of the Ganzi loess shows that rainfall in the eastern TP has varied dramatically, and the wettest periods over the last glacial cycle were the LIG and the Holocene. (c) The ISM has influenced precipitation changes since the LIG in the eastern TP. The ISM and precipitation in the eastern TP were mainly driven by the combined effect of orbital changes, global ice volume, atmospheric CO2 concentration, and internal climate forcing on the glacial‐interglacial timescale.