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Authors |
Sun, YB; Liang, LJ; Bloemendal, J; Li, Y; Wu, F; Yao, ZQ; Liu, YG |
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Abstract |
Millennial-scale monsoon variability has been investigated intensively using loess-based proxies; however, the amplitude and rhythms of millennial-scale signals have seldom been disentangled from the background glacial-interglacial changes. Here we present the results of high-resolution scanning X-ray fluorescence analysis of a 75-m-thick loess sequence from the north-western Chinese Loess Plateau to address glacial-interglacial to millennial monsoon variability over the last two climatic cycles. Variations of the Si/K, Fe/K and Ca/K ratios are separated spectrally into low-and high-frequency components corresponding to glacial-interglacial and millennial-scale monsoon variability, respectively. The results indicate that the three elemental ratios exhibit similar glacial-interglacial variability but with varying spectral densities at the 100-, 41- and 23-kyr periodicities. Millennial-scale variability is quite similar between the three elemental ratios, and comparable to those inferred from records of Chinese speleothem δ18O, Greenland palaeotemperature and North Atlantic cooling events. Comparison of various proxies indicates the broad similar magnitudes of abrupt climate changes, at least during the last two glacial-interglacial cycles, whereas the timing and amplitude of abrupt climatic events are not well correlated. We suggest that refinement of loess chronology and intensive data-model integration in the future are critical to decipher the characteristics and dynamics of rapid monsoon changes. |
© 2015 Institute of Earth Environment,CAS