十五万年来临夏黄土粒度变化的气候记录

A150 KA CLIMATIC RECORD OF LOESS FROM GRAIN—SIZE DATA IN LINXIA, GANSU

风成黄土沉积的粒度变化受控于风力强度及大气环流,具有气候学意义。根据临夏北塬黄土剖面的粒度资料,结合沉积物的年代测定,研究了粒度参数随时间的变化恃征,表明临夏黄土自150ka以来,粒度参数反映的气候变化经历了8个主要阶段,完全可以与南极东方站冰岩芯温度记录及深海氧同位素阶段对比。但气候阶段的始末在时间上有一些差异。可能反映不同气候区域对全球气候变化的响应不同,而粒度参数与全球海面变化却非常一致;海面的升降及温度变化也控制和影响着大陆环流系统。最后,从粒度变化讨论了冰期、间冰期影响中国大陆环流系统的变化。

The grain—size change of aeolian loess controlled by wind intensity and atmospheric circulation has a climatic significance. This paper deals with the change features of the grain—size against time based on the grain—size data of loess in the Beiyuan section and three ^(14)C datings and four TL datings. The grain—size parameters show that the climatic variation has eight main stages since 150 ka B. P. and corresponds well with the temperature record of Vostok ice core, Antarctic and the oxygen isotopic stages of deep—sea core. The corresponding climatic stages are of some differences at the beginning and ending of the stage and could mean that the response of differential climatic region to global climatic change is different. At the same time, the change of loess grain—size coincides with the global sealevel change, and the changes of sealevel and sea surface temperature also control and influence the continental circulation systems. Finally, the change of continental circulation systems in glacial—interglacial periods in China are discussed based on the grain—sine data.