No abstract

Eolian dust deposits in north China provide an excellent means of determining past variations in continental paleoclimate and atmospheric circulation. However, debate still exists on which deserts in east Asia are the dominant sources of Chinese loess and whether the dust provenance has shifted significantly at different time scales. Here we present new constraints on the provenance of fine‐grained dust deposited on the central Chinese Loess Plateau (CLP) by combining electron spin resonance signal intensity and crystallinity index of fine‐grained quartz contained in samples from two loess‐paleosol sequences. Our results show that the fine‐grained dust deposits on the CLP originate mainly from the Gobi desert in southern Mongolia and the sandy deserts in northern China (primarily the Badain Juran and Tengger deserts), rather than from the Taklimakan desert in western China, at least during the last climatic cycle. The dominant source of fine‐grained dust varied significantly, from southern Mongolia during cold periods, to northern China during warm periods. The glacial‐interglacial provenance fluctuations are strongly coupled with changes in the intensity of the near‐surface northwesterly winter monsoon.

No abstract

[1] Late Quaternary hemipelagic sediments in the Japan Sea contain aeolian dust from East Asia which potentially records past variations in the Asian monsoon and the westerly jet. However, extracting information about aeolian dust from Japan Sea sediments is difficult because the sediments also contain detrital material from the Japanese Islands. Here we present a method for extracting the aeolian dust components from Japan Sea hemipelagic sediments using provenance analysis of different size fractions. Hemipelagic sediments of the Japan Sea can be described by a combination of two populations characterized by lognormal grain size distributions with different median grain sizes, which are called the coarser (2-15 mm) and the finer (<10 mm) populations. We characterized these populations on the basis of provenance analyses, using the electron spin resonance (ESR) signal intensity and crystallinity of quartz. The results suggest that quartz in the coarser population has been mostly supplied from Northern China and Siberia/northeastern China by aeolian transport, whereas quartz in the finer population has been dominantly supplied by rivers draining the Japanese Islands.