关键词: 平潭岛, 海岸风成砂, 粒度特征, 古气候

Abstract: Located on the Pingtan Island of eastern Fujian Province, the Baiqingxiang section consists of greyish-white to yellow aeolian sands(hereafter, "white aeolian sands") and red aeolian sands(hereafter, "old red sands") that alternate to some extent with red aeolian sands with an age of 150 to 20 ka BP. Our grain-size analyses showed that both the old red sands and the white aeolian sands are mainly sand grains, with minor silt and low clay contents. Their grain-size characteristics and parameters differ greatly from those of local modern beach sands, but are similar to those of modern aeolian sands, and both the old red sands and the white aeolian sands contain more silt and clay than modern aeolian sands. The alternation in their features suggests that the eastern coast of Fujian Province has experienced four warm-humid(W) periods and four cold-dry(C) periods from 150 to 20 ka BP:W4(133 to 117 ka BP), W3(108 to 99 ka BP), W2(84 to 67 ka BP), and W1(50 to 20 ka BP), and C4(150 to 133 ka BP), C3(117 to 108 ka BP), C2(99 to 84 ka BP), and C1(67 to 50 ka BP). These periods correspond well to the climate fluctuations recorded in the LR04 benthic stack curves, the 65 N summer solar radiation data, and relative sea-level changes. This suggests that sand deposition on China's southeastern coast has been subject to global climate factors, such as solar radiation, the East Asian monsoons, and sea-level fluctuations, at a scale of approximately 10 ka from 150 to 20 ka BP.

Key words: Pingtan Island, coastal aeolian sands, grain size, paleoclimate