乌伦古湖沉积物粒度特征及其古气候环境意义

利用乌伦古湖沉积钻孔的粒度资料,分析了粒度频率曲线、粒度参数和粒度组成等粒度特征,并探讨了乌伦古湖粒度代表的古气候意义。结果表明乌伦古湖沉积物频率曲线主要是正态单峰型,反映流水作用为主要沉积作用。岩芯下部（225197cm）沉积物分选较差,偏度和尖度较大,为浅水沉积环境;中部（197103cm）分选由差变好,物源由复杂变单一,为浅水沉积向深水沉积过渡环境;上部（1030cm）分选较好,物源单一,中值粒径减小,反映了湖水位的下降。沉积物粒度特征反映了乌伦古湖地区全新世降水、流水和风力作用以及湖面水位高低的变化。乌伦古湖一万年来的古气候环境演化大致经历了102507720cal.aBP的干旱、77202800cal.aBP的湿润和2800cal.aBP以来的偏干三个阶段。 

Grain-size Characteristics of Wulugu Lake Sediments and Its Palaeoclimate and Palaeoenvironment Implication

Located in the westerly and arid area, Wulungu Lake is sensitive to climatic and environmental change. The grain-size characteristics of its sediments indicate that the variations of precipitation, hydrodynamics and wind action, and the lake level changes. The grain size characteristics of Wulungu Lake sediment are analyzed in this paper, including grain-size distribution, grain-size frequency curves and grain-size parameters. Based on the analysis of the characteristics of the grain-size frequency curves and grain-size parameters of the lake sediments, two action and two depositions such as fluvial and windy action, low-lake deposition and high-lake deposition are discussed. The results indicate that the fluviation was the main action and source of sediment in Wulungu Lake. And the Wulungu Lake had experienced three main environmental evolution stages since Holocene. It was dry in 10250 -7720cal. aBP, wet in 7720 -2800 cal. aBP, and dry again after 2800cal. aBP, respectively.