Timing and structure of the mid-Pleistocene transition: records from the loess deposits of northern China

摘要

The mid-Pleistocene transition (MPT) from obliquity- to eccentricity-forced climate variations has been extensively documented within the oceanic realm. Using a collection of orbitally tuned records of palaeoclimatic change from the loess sequences of northern China, we have analysed terrestrial palaeomonsoon behaviour since 1.5 Ma and characterised the structure of the MPT. Wavelet analysis of a stacked magnetic susceptibility record from the loess sequences indicates that the onset of 100pkyr cyclicity was synchronous in both global ice volume and the East Asian monsoon system. However, analysis in the time domain reveals that during the MPT 'interim' period the East Asian winter monsoon appears to have weakened whilst global ice volume was increasing, indicating that the palaeomonsoon was not the primary forcing mechanism responsible for driving the global climatic change.