程海近代气候变化的化学记录

RECENT CLIMATIC CHANGES AND THE CHEMICAL RECORDS IN CHENGHAI LAKE

通过对程海沉积物化学组分及其比值变化剖面的精细剖析 ,辨识了程海沉积物碳酸盐含量、Ca O/ (Mg O· Al2 O3)和 (Ca O+K2 O+Na2 O) / Al2 O3比值的环境指示意义 ,初步探讨了程海区域的气候短尺度波动。研究结果表明 ,程海区域主要表现为暖干与冷湿相交替的气候演替类型 ,且存在约 5 0

Carbonate content and CaO/(MgO·Al 2O 3) ratio of the Chenghai Lake sediments can indicate cold and warm climatic changes,while(CaO+K 2O+Na 2O)/Al 2O 3 ratio can show dry and wet changes.Through correlations,it is found that the carbonate content and CaO/(MgO·Al 2O 3) and (CaO+K 2O+Na 2O)/Al 2O 3 ratios have good positive synchronous quasi periodical fluctuations,indicating that the dry—wet changes in the Chenghai Lake region often follow the cold—warm changes,and these two changes are synchronous with a quasi period on 50 year time scale.Climatic changes in the Chenghai Lake region show a model,that is,dry corresponding with warm and wet with cold,alternating with each other,showing an evident difference of climate from Southeast monsoon area where climate is generally warm—wet and cold—dry.Geographic position,special geomorphic features and strong influence of the Qinghai—Tibet Plateau uplift on the Southwest monsoon may be the causes of such difference.