通过分析河西走廊花海古湖泊沉积物中的盐类矿物组成,结合年代序列,重建了花海晚冰期以来湖泊演化过程及其对气候变化的响应。结果表明:晚冰期及新仙女木时期,花海湖泊以芒硝沉积为主,属硫酸盐型湖泊,湖水的盐度较高且周期性波动频繁;全新世早期(10.47cal ka BP以前),湖泊以洪泛堆积和风成沉积为主,揭示了湖泊萎缩、甚至干涸;全新世早期至全新世中期(10.47~8.87cal ka BP)盐类矿物以碳酸盐沉积为主,为碳酸盐型湖泊,湖水淡化,湖泊水位开始逐渐回升;全新世中期(8.87~5.50cal ka BP)盐类矿物呈现一定的波动变化,其中,8.8 cal ka BP时期盐类矿物以硫酸盐沉积为主,湖泊由碳酸盐型转化为硫酸盐型,湖水咸化,盐度升高;随后盐类矿物以碳酸盐沉积为主,湖泊由硫酸盐型转化为碳酸盐型,湖水盐度降低、湖泊扩张;全新世中晚期(5.50cal ka BP以来)出现沉积间断,表明中晚全新世时期湖泊逐渐萎缩。在全新世期间,花海湖泊千年尺度演化过程揭示了该区域气候干湿状况受亚洲季风和西风共同控制的影响。
英文摘要:
Based on salt mineral composition and chronology,we reconstructed the lake evolution of Huahai Lake since the Late Glacial in the marginal area of the Asian monsoon in the Hexi Corridor of China.Results show that mirabilite deposition in the Late Glacial and Younger Dryas periods indicated high water salinity. Alluvial and aeolian deposition before 10.47 cal ka BP indicated an arid environment.During 10.47-8.87 cal ka BP,carbonate mineral deposition indicated water salinity decreasing and high lake levels.Between 8.87cal ka BP and 5.50 cal ka BP,salt minerals fluctuated intensively.In 8.8 cal ka BP,the layers were formed mainly on sulphate depositions,suggesting a salination process.After that,carbonate mineral became the main mineral in the layers and the lake salinity was low.After 5.50 cal ka BP,hiatus indicated the lake shrank.Holocene millennial-scale lake evolution and climate changes in Huahai Lake was controlled by the Asian monsoon and westerly winds.