关键词: 沉错, 湖泊沉积物, 湖面波动, 环境变化, 粒度

Abstract: Grain size is one of the useful indices in the lacustrine sedimentary research. By directly indicating the water impetus during the sedimentary period, the grain size of lake sediments indirectly reflects the supplied water volume changes of the lake. Because the lake water volume is greatly influenced by climatic factors, such as precipitation, temperature and induced glacier melting water, the grain size provides more information to elucidate the environmental changes. By the analyses of the grain size parameters and the comparison with other proxies of the Chen Co sediments, four stages of environmental changes since ca. 1400 years ago have been distinguished. 1) Ca. 593～821 A.D. was a high lake level period accompanied by frequent fluctuations. It implies relatively wet climatic conditions with multi time alternative changes. 2) Ca. 821 1343 A.D. was a long and stable wet period, during which the lake enlarged and the lake level rose. 3) Ca. 1343 1892 A.D. was a climatically complex period. The inflow water violently increased around ca. 1602 A.D. while the lake was in the shallow water status in other periods. It suggested that the supplied water of the lake was relatively weak. 4) Ca. 1892 1998 A.D. was another stable period with the light lake level variations. Ca. 1892 A.D. was an obvious borderline for showing the supplied water impetus changes. These environmental changes reflected by the grain size of Chen Co lake sediments were well supported by other proxies and proved by other research results.

Key words: Chen Co, environment changes, grain size, lake level fluctuations, lake sediments