安固里淖自生碳酸盐碳氧同位素组成与环境

Authigenic Carbonate Oxygen and Carbon Isotope in Angulinao Lake and Environment

湖泊自生碳酸盐碳氧同位素变化是反映内陆湖泊水环境与气候环境的重要指标.通过在河北坝上安固里淖钻取沉积样柱,分样进行自生碳酸盐矿物类型分析和碳氧同位素分析,结合剖面的纹层年代以及粒度分析和易溶盐分析,对湖泊地区的全新世古环境进行了探讨:8507～7909aB.P.,湖区气温较高,蒸发量大,夏季风先减弱随后增强.7909～7004aB.P.,冬季风较强,气温低,蒸发量小,湖水盐度高;7004～5491aB.P.,气温较高,降雨量大,湖水冰冻时间短,相当于大暖期鼎盛阶段;5491～4617aB.P.,大气湿度低,气温低,冬季风较强,湖泊冰冻时间长,代表大暖期气候剧烈波动阶段;4617～574aB.P.,冬季风较强,降水量少,河流补给少,湖泊冰冻时间较长;574aB.P.至今,冬季风较弱,冰冻时间缩短,气候向暖湿发展.安固里淖自生碳酸盐碳氧同位素反映的环境变化与我国北方地区的全新世环境以及海平面的变化基本一致.

Authigenic carbonate oxygen and carbon isotope evidence in lake sediment is an important proxy to reflect lake environment and climatic change. The paper centers on a sediment column in Angulinuo Lake, Bashang Plateau, Hebei province, and analysis of mineral type of authigenic isotopes, oxygen and carbon isotope. Comparing with the lamination age and change of grain size and soluble salt, the researchers have discussed the palaeoenvironment in area of Angulinao Lake in Holocene.During 8 507～ 7 909 a BP, air temperature is high and evaporation is large, summer monsoon is weak firstly then become strong; during 7 909～7 004 a BP, winter monsoon is strong and cold, evaporation is low, the salt of lake is high; during 7 004～5 491 aBP, air temperature is higher, precipitation is large and the period of ice time is short, it is equivalent to the Hypothermal of Hypothermal of Holocene; during 5 491～4 617 a BP, the humidity and temperature is low, winter monsoon is strong, the ice time of lake is long, this period is the stage of drastically variating during Holocene optimum time; during 4 617～574 a BP, winter monsoon is strong and precipitation is little, the ice time of lake is long; since 574 a BP, winter monsoon became weaker, climate is becoming warm and humid. The environment change reflected by authigenic oxygen and carbon isotope coincides with the environment change in north of China and China sea in the same period.