山东地区黄土研究综述

A Summary of Loessial Researches in Shandong

山东地区黄土开始堆积时期普遍较晚,目前已见的剖面中,以青州傅家庄剖面堆积厚度最大(30m以上),起始堆积时间最早,出露的最老层位为L9,TL测年时间约为0.8MaB.P.。山东地区黄土成因类型多样,物质来源广泛,其岩性特征与其他地区的黄土有明显的差别;在本地区内部,黄土的差异也比较明显,大体可分为两大成因分布区:渤海湾滨海与岛屿区和鲁中山前区。前者黄土粒度较粗,且普遍含有海相微体化石,其物质来源主要为末次冰期时期出露的渤海陆架物质,西北气流携带而来的内陆远源物质占次要地位。而后者黄土类型成因多样,东部的潍坊、青州黄土分布区,受到末次冰期时强劲冬季风的影响,物质来源主要为北部出露的渤海湾,向西至淄博、济南地区则已逐渐过渡为西北内陆风尘物质成分占据主导。

The loess of Shandong, located in the margin of Eastern China,shows some stripes as a whole,especially on the windward slopes,the terraces of the central mountainous region and northwest coastal zone of Jiaodong hills.Among the loess sections distributed in Shandong,the Fujiazhuang section(30m)at Qingzhou is the best,and can be regarded as the typical section of Shandong.TL dating results of Fujiazhuang loess show that the lowest layer of Shandong loess is L9,with the age of 0.8 Ma B.P.,which accords with the third borderline determined by Liu Dongsheng.Many sections have the tertiary red clay layers. Based on the main researches on loess spreading all over Shandong enumerated in this paper,the authors conclude that the grain sizes, composition and origins of loess between Shandong and inland regions is obviously different,and the same within Shandong. Based on the characters, two areas can be allocated: the coastal district, islands and islets of the Bohai Sea and the central district of Shandong.The former loess in which many tiny marine fossils have been found and whose grain sizes are much coarser, however,the latter has more complex material sources and characters.According to the analytical results of grain sizes and spore,the sea level of Shandong has been known to have several fluctuations between transgression and regression since the middle Pleistocene,so bald Bohai shelf was the main material sources for the continental loess during ice ages,and it severely influences the loess of Qingzhou,Weifang etc,the districts of the central district of Shandong. But the loess of Zibo and Jinan,the west of the central district, mostly originates from western Gobies and deserts.