西藏纳木错晚更新世以来古降水量变化及其环境响应

通过对西藏面积最大(1940km2)和海拔最高(4718m)的大湖-纳木错的调查,发现纳木错周缘有大面积分布的湖相沉积。U系法和14C法测年结果表明,纳木错沿岸湖相沉积的时代为晚更新世和全新世。根据纳木错周缘不同时代湖相沉积物的范围分布的变化,探讨了湖泊演化,计算出纳木错流域古降水量。研究结果,本区自晚更新世以来气候环境由湿润转向干旱,自全新世以来降雨量呈下降趋势。 

VARIATION OF PRECIPITATION IN NAM CO,TIBET,SINCE THE LATE PLEISTOCENE AND ITSENVIRONMENTAL RESPONSE

Field surveys of the Nam Co-a large lake with the biggest area (1940 km²) and highest elevation above sea level (4718 m) in Tibet show that there are extensive lacustrine sediment around the Nam Co.Uranium-series and ¹⁴C dating indicate that the lacustrine sediments along the shores of the Nam Co are late Pleistocene and Holocene in age.The lake evolution was studied according to the change in distribution of lacustrine sediments of different ages around the Nam Co and the paleo-precipitation in the Nam Co drainage area was calculated.The study indicates that the climate in the study area turned from wet to dry since the late Pleistocene and that the precipitation has had a tendency of decrease since the Holocene.