末次冰期间冰段腾格里沙漠古湖泊与环境演化

Comprehensive field investigations and laboratory analyses show that palaeolakes, including fresh-mesohaline water Megalake Tengger and other semi-connected, isolated water bodies, during late Pleistocene covered an area of more than 20,000 km2, which is more than half of the Tengger Desert in NW China. Stratigraphic correlation and chronological evidence indicate that before ca. 42,000 yr B.P. the area was more arid. The palaeolakes started to develop around 40,000 uncal. 14C yr B.P. but until 37,000 14C yr B.P. their scope was limited. High water levels established from 35,000 14C yr B.P. lasted until 22,000 14C yr B.P. Lake levels regressed between 22,000 and 20,000 14C yr B.P. but transgressed from 20,000 to 18,600 14C yr B.P. Subsequently, water level declined further and the Megalake Tengger finally desiccated at around 18,000 14C yr B.P. . Megalake Tengger possessed a fresh-mesohaline water property, implying that the regional precipitation increased significantly. During the period of Megalake Tengger, the climate was warmer-humid than present. The annual rainfall was 250 to 350mm more than that of today and the temperature was 1.5 to 3.0°C higher.. Geochemical data, palynological evidence and grainsize variations demonstrate that the lake levels had fluctuated greatly with the climate changes and these fluctuations can be correlated with the Dansgaard-Oeschger and Heinrich events. All the evidences do not support the hypothese that the formation of the paleolakes and the fluctuations of the climate are relate with sea level changes during the late glacial interstadial..

通过对腾格里沙漠、深海氧同位素第3阶段古湖泊范围、性质、深度、水分来源的分析，湖喑粱甏蛄械慕ⅲ肪承畔⒌奶崛『褪只Ｄ猓亟ㄌ诟窭锷衬?阶段晚期古气候特征及演变序列，探讨该时段晚期古气候环境的分异特征、偶合关系、变化机理及与全球变化关系，这对于加深认识中国西部气候环境的演化过程及演化趋势有重要意义。.