青海湖、岱海的湖泊碳酸盐化学沉积与气候环境变化

LACUSTRINE CARBONATE CHEMICAL SEDIMENTATION AND CLIMATIC-ENVIRONMENTAL EVOLUTION --A CASE STUDY OF QINGHAI LAKE AND DAIHAI LAKE

于1986—1989年,为探讨全球气候与环境变化的湖泊响应,选择了季风带边缘的青海湖和岱海开展了湖泊碳酸盐化学沉积与气候环境关系的分析研究。发现青海湖近500年来碳酸盐沉积减弱段与小冰期的冷湿气候背景一致;岱海晚更新世以来碳酸盐沉积增强段与冰期的干冷气候吻合。还从内陆湖泊的有效湿度与碳酸盐化学沉积的关系和碳酸盐含量的垂向变化规律,对两区域气候与环境的演化过程、特点和规律进行了分析。

Temperature and precipitation are clima ic factors which control the water balance of inland lakes in semi-arid to semi-humid areas to the extent that they may definitely cause fluctuation in lake capacity, water mineraliza ion and carbonate sedimentation. Thus analysis of carbonate sediments in geological sections may give useful information on past climatic and environmental evolutionary trends. According to the pattern of fluctuation of carbonate sediments in Qinghai and Daihai lakes, the climate changes over the past 500 a in Qinghai Lake suggest that during the little ice age the climate was cold and humid, during the temperature increasing period, warm and dry, resulting in a 100 a meta-cyclicity. Dry and cold ice age, warm and humid interglacial periods have been the mjor climatic features in Daihai Lake since the Late Pleistocene. Drastic climatic changes took place during the transition from glacial to interglacial period. The water balance of lakes in the marginal monsoon areas suggested that they were sensitive to climatic changes.