鄱阳湖沙山高分辨率沙质地层及其冬季风气候信息记录的初步探究
The High-Resolution Sandy Stratigraphy and Its Record of Climate Change During the Late Little Ice Age in Poyang Lake Region

位于鄱阳湖流域的长江、赣江等河谷、河漫滩的下风方向,由于处于冬季风强烈的东亚季风区,在高频率出现的大风、强风天气情况下,受风力吹蚀作用,常形成区域性的沙山堆积.沙山纵向垄状地形发育,其上风方向,槽、沟与碟形坑等侵蚀地貌发育,其下风方向,纵向沙垄发育.通过对样品的光释光年代测试和粒度频数分析,浅析星子PBL剖面的小冰期风积地层,揭示了小冰期晚期持续近60年左右的一次冷期,这个冷期以突变开始,以渐变结束,其清晰程度在其它地质记录中是不曾发现的.研究发现鄱阳湖沙山纵向沙垄往往具有缓倾斜的前积与侧积,层理(薄层与细层)往往较稳定,对揭露冬季风气候信息具有重要的意义.
With OSL dating and grain size analysis,ca.270 years of proxy records of climate change during the late Little Ice Age are developed based on Botou Li profile1 and profile2 in sand hills in Xingzi County.Comparison of some proxy records from Botou Li profile,dryness/wetness record from Meteorological Research Institute of the centeral weather bureau(1981)and records of mean temperature anomaly in the mid and east of China after Wang(2007),it is concluded that the content of the third grain size totality(dust particle)(Ctp(%))in sand hills indicated the regional humidity and/or probably is a proxy of regional flood flat area,average grain size of the first totality (Mdfp) is a proxy record of winter monsoon intensity,sediment consequences of Botou Li section,with ultrahigh-resolution,clearly record a cold interval(ca.60 years)in the late Little Ice age.The cold period,timely corresponding to the stage of Dalton minimum of sun spot number,start abruptly and end gradually indicated by the record of median grain size of the first totality (Mdfp)