Correlation of the magnetic susceptibility stratigraphy of Chinese loess and the marine oxygen isotope record: chronological and palaeoclimatic implications

Abstract

The thick deposits of wind-blown silt of the Loess Plateau in central China constitute arguably the most important terrestrial record of the late Pliocene and Pleistocene climate. Magnetic susceptibility stratigraphy has proven extremely useful for quantifying the palaeoclimatic record of Chinese loess, with intervals of high magnetic susceptibility corresponding to warm, humid interglacials and intervals of low susceptibility to cooler, drier glacials. Several workers have noted that the magnetic susceptibility stratigraphy strongly resembles the marine oxygen isotope record, for which a high resolution chronology is available from tuning to the frequencies of Earth orbital parameters. Attempts have been made to correlate the two records statistically and we use this approach to generate a new magnetic susceptibility time series for the central Chinese Loess Plateau. Our results suggest that the two records are sufficiently similar over the interval ca. 0–1.5 My BP for this approach to yield a useful age model for loess accumulation. Spectral analysis of the resulting magnetic susceptibility time series clearly shows that the growth of 100 ky variance, which occurs in the marine oxygen isotope record after about 1 My BP, also occurs synchronously in the magnetic susceptibility record, reinforcing recent suggestions of a strong linkage between the high latitude northern hemisphere and the Asian climate. We also show that a significant improvement in the strength of the loess magnetic susceptibility-marine oxygen isotope correlation occurs after about 1.5 My BP, which corresponds to a significant increase in the rate of sediment accumulation across the Loess Plateau.