Eolian quartz flux variations in Cheju Island, Korea, during the last 6500 yr and a possible Sun–monsoon linkage

We have obtained a high-resolution sedimentary record covering the last 6500 yr from a maar in Cheju Island, Korea, in order to reconstruct the history of variations in the eolian quartz flux (EQF) and hence Asian dust. The long-term variation of EQF reveals three intervals: a period of high EQF (4000–2000 cal yr B.P.) and two periods of low EQF (6500–4000 cal yr B.P. and 2000 cal yr B.P. to present), which have been affected by the East Asian monsoon due to insolation change and the cold air activity in high latitudes correlated with polar high-pressure systems. This long-term variation is superimposed by millennial- and centennial-scale fluctuations with periodicities of 1137, 739, 214, 162, 137, 127, and 111 yr, implying drier conditions in the source areas in China. The detrended EQF record correlates visually and statistically (cross-spectral analysis) with the atmospheric Δ14C record (solar proxy). The centennial-scale variability in EQF may be affected by the solar activity through the Sun–East Asian monsoon linkage.

Eolian Quartz Flux to Lake Biwa, Central Japan, over the Past 145,000 Years

Eolian quartz flux (EQF, g cm−2(103 yr)−1) to Lake Biwa, central Japan, provides direct information on variations of the East Asian winter monsoon. Lake Biwa sediments spanning the past ca. 145,000 yr are characterized by two main periods when EQF values were significantly greater than 5.50 g cm−2(103 yr)−1, and two main intervals during which EQF values were lower. Two periods with EQF values >5.50 g cm−2(103 yr)−1occurred from ca. 145,000 to 125,000 and 73,000 to 13,000 yr B.P., while times of lower EQF values occurred from ca. 125,000 to 73,000 yr B.P. and around ca. 5500 yr B.P. Between ca. 125,000 and 73,000 yr B.P., three minimum EQF values and two intervening peaks of slightly higher EQF values are recorded. EQF increased markedly from ca. 73,000 to 13,000 yr B.P., whereas between ca. 53,000 and 20,000 yr B.P. the values recorded were relatively lower than those recorded during either the preceding or the subsequent episodes. The data imply that the East Asian winter monsoon strengthened during the periods when EQF values were high, and weakened during the intervals with low EQF values. The EQF record of Lake Biwa can be correlated with the grain-size record of the quartz fraction in Chinese loess and with the SPECMAP marine δ18O record. However, the EQF record apparently lags ca. 5000 yr behind the loess and δ18O records during stage 6/5 and 2/1 transitions and ca. 10,000 yr during stage 5/4 transition. These apparent lags could be due to problems with the chronology; alternatively, they may imply that the eolian quartz flux depended more on the extent of dust source regions than on wind intensity during these transitions.