猪野泽中全新世干旱事件时空范围和机制

以亚洲季风边缘区石羊河流域终端湖猪野泽为例,结合最新的沉积物年代、岩性、指标及古湖泊岸堤研究结果,从时间和空间尺度上探讨了猪野泽中全新世干旱事件时空范围和机制。从空间上对比了猪野泽中全新世地貌及沉积物岩性和指标,并配合石羊河中、上游地区的中全新世沉积剖面进行研究。在时间尺度上分析了猪野泽和石羊河流域近百个全新世测年结果,最终得出猪野泽地区在8.0~7.0 cal ka B.P.期间存在百年尺度的干旱事件,而不是以前研究提出的距今7000~5000日历年期间2000 a尺度的干旱事件,并且这次极端干旱事件影响范围主要在石羊河中、下游地区,对石羊河上游地区影响较小。根据时空尺度分析对猪野泽中全新世干旱事件机制进行讨论,结果表明这次干旱事件主要是由流域气候条件特征和水热配比改变所引起的,而不是以前研究提出的亚洲夏季风减弱导致。

The Spatial and Time Scales for the Dry Mid-Holocene Event in Zhuye Lake

In this paper,the sediments and paleo-lakeshores data in Zhuye Lake and surrounding areas,the terminal lake of Shiyang River drainage basin,in the marginal area of the Asian monsoon,were synthesized and then the spatial and time scales around Zhuye Lake and in the drainage basin were discussed.In the spatial scale,this study compared the results of mid-Holocene geomorphology and lake sediments in Zhuye Lake,and we also studied the mid-Holocene sections in the middle and upper regions of the Shiyang River.In the time scale,nearly a hundred dating results in Zhuye Lake and the drainage basin were compared.Then it was concluded that there was a centennial-scale extremely dry interval occurring during 8.0-7.0 cal ka B.P.in Zhuye Lake,instead of the previous study which reported the dry interval during 7000-5000 cal a B.P..And the centennial-scale extremely dry could be detected in the middle and lower reaches of the drainage basin,but the upper region was less affected.The centennial-scale extremely dry interval might be related to the changes in water and heat balance,and the characteristics of climatic conditions in this drainage lead to the different responses to the dry interval in the different locations of the drainage basin.There were no obvious evidences showing that the dry interval was related to the Asian monsoon weakening.In this paper,the time and spatial scales analysis of the dry mid-Holocene in Zhuye Lake provide some clues and ideas for the dry mid-Holocene studies in other parts of the Asian monsoon domain.