Geomorphology, Deposition and Lake Evolution of Dabusu Lake, Northeastern China

大布苏湖地处松嫩平原南部,是一个封闭的构造断陷糊.湖区地貌类型复杂,沉积环境独具特色.根据地形面的分异和沉积物特征,结合14C测年,确定大布苏湖形成于晚更新世晚期.湖泊形成的早期,曾经历了深湖的发育阶段.全新世以来,湖面波动式降,并有两次规模较大的扩张和收缩时期,形成了两个完整的湖进、湖退沉积旋回.晚全新世以来,气候干燥,风力作用活跃,湖面明显萎缩.形成我国东部地区极为罕见的盐湖;The Dabusu Lake, located in the Songnen (Songhuajiang River-Nenjiang River) Plain, northeastern China, is a closed tectonic fault lake.The investigation on the geomo rphology and depositional ty pes of the basin revealed that the evolution process of the Dabusu Lake was signif icant for interpreting regional envi ronmental evolution. On the basis of the investigat ion as well as 14C dating, we concluded that the Dabusu Lake was formed in late-Pleistocene.In early times of lake evolution, the Dabusu Lake was a deep lake.Since Holocene, the lake level fluctuated with two enlarging periods and two shrinking preiods, showing that the lake has undertaken two complete deposit ional cycles of lake advance and ret reat.Since mid-Holocene, due to the dryer climate and stronger wind force, the lake level dropped and lake shrank.From then on, the lake gradually turned into a salty lake, which was rare in Northeastern China.