三门峡地区末次盛冰期至全新世早期的古季风事件

Paleomonsoon Events from the Last Glacial Maximum to Early Holocene in Sanmenxia Area

通过三门峡地区小刘寺剖面黄土- 古土壤序列磁化率曲线和粗颗粒组分含量曲线的研究,发现它们分别指示的夏季风和冬季风变迁在末次冰消期向全新世转变时的新仙女木事件中显示不同的变化特征。夏季风的加强过程对应于冬季风的大幅度波动,气候为凉湿背景上的冷湿与暖湿振荡。冰后期的早期为全新世第一暧期。夏季风强盛对应于冬季风衰弱的湿暖气候,它由夏季风锋面降水的穿时性所决定,在华北地区为全新世适宜期。8 kaBP 前后为夏季风偏弱对应于冬季风偏强的干冷气候,是具有普遍意义的全新世第一冷期。这3 次古季风事件可与格陵兰冰芯记录进行较好的对比。

Through the study of the loess-paleosol sequence in Xiaoliusi profile at Sanmenxia area, it is revealed that the summer monsoon variations indicated by magnetic susceptibility and the winter monsoon variations indicated by grain size showed different patterns during the Younger Dyras period, the shift period from the last deglaciation to Holocene epoch. During this period the climate changes in this area were characterized by the oscillations of cold-humid climate and warm-humid climate against the background of cool-humid climate, with the enhanced summer monsoon corresponding to the large fluctuating winter monsoon. The climate in the early post-glacial period in this area in the enhanced summer monsoon corresponding to the declined winter monsoon decided by the diachronism of summer monsoon's hydrometeor front is humid and warm. We call it the first Holocene warm stage, which corresponds to the Holocene optimum in North China. The climate was cold and dry around 8kaBP, the first Holocene cold stage.This is of universal significance in that during this period the declined summer monsoon corresponded to the enhanced winter monsoon. The above three-paleomonsoon events in this area can be correlated well to Greenland ice core records.