关键词: 青峰老红砂, 夏季风沙, 冬季风沙, 末次间冰期

Abstract:

Old Red Sands mainly distributed in China's southeast coast and the islands are special red sand deposits during Quaternary. They were considered to be formed by vast continental shelf sands and beach sands transported under strong winter monsoon and deposited along the coast during 68-9 ka B.P.,the last glaciation, low sea stage. In this study, 114 Old Red Sand samples,130 winter wind sand samples and 60 summer wind samples were collected from typical Old Red Sand area Pingtan Qingfeng. The grain size measurements for the samples show that the size frequency distribution of winter wind sands peaked at 400 μm, of summer wind sands at 280 μm, and of Old Red Sands peaked at 300 μm. Which inconsistent with the winter wind sands. Experiments show that mixing summer wind sands sand winter wind sands with 7∶3 can fit Old Red Sands grain-size distribution. It is indicated when Qingfeng Old Red Sands depositing, the lasted or intensity of the summer monsoon is much larger than the winter monsoon, which corresponds to the climate warm periods, rather than last glaciation. OSL dating for Qingfeng Old Red Sands section with 4 natural layer shows a bottom-up years of the 122.5±6.7 ka B.P., 97.7±6.1 ka B.P., 83.1± .2 ka B.P., 61.9±3.4 ka B.P., mainly corresponding to the last interglacial , Qingfeng Old Red Sands formed during the last interglacial.

Key words: Qingfeng Old Red Sand, summer monsoon sand, winter monsoon sand, the last interglacial