Abstract:

Poyang Lake,situated in the East Asian monsoon region,is one of the regions most sensitive to Holocene climate change. Consequently,investigating the climatic variations of Poyang Lake since the Holocene holds significant importance. Phytolith analysis offers distinct advantages for reconstructing paleoclimate,and abundant phytoliths have been retrieved from sedimentary cores of Poyang Lake. However,there has been limited in-depth exploration into the mechanisms of climate evolution and regional comparisons in phytolith-based paleoclimate studies of Poyang Lake during the mid-to-late Holocene. To reconstruct the climate evolution process of Poyang Lake over the past 5700 years and examine its underlying mechanisms,phytoliths from the ZK01 borehole were utilized as indicators. Principal component analysis was employed to analyze the phytolith assemblages,yielding principal component scores that reflect changes in climate wetness and dryness. Based on variations in phytolith assemblages and the Warmth Index,three major climatic stages were identified. The findings indicate: (1)Over the past 5,700 years,four relatively dry periods and three relatively humid periods have occurred in the Poyang Lake area. Phytolith records show sensitivity to global events such as the 4.2 ka event and the Little Ice Age.(2)There is a good correspondence between phytolith records in the Poyang Lake area and stalagmite δ¹⁸O records that respond to East Asian summer monsoon(EASM)variability. When the EASM weakens,the Poyang Lake region tends to be wetter,and vice versa.(3)The phytolith records from the Poyang Lake region,situated in the southern part of the East Asian monsoon area,exhibit a degree of comparability with pollen-based precipitation records from the Daihai region in North China. This suggests an anti-phase spatial pattern of precipitation between the southern and northern regions of eastern China’s monsoon area during the mid-to late Holocene.(4)Since the mid-Holocene,ENSO activity has influenced the hydrological climate of the Poyang Lake region. Periods of increased ENSO intensity often coincide with humid climate phases in the Poyang Lake region,suggesting that variability in ENSO intensity may reflect changes in the strength of El Niño or La Niña.

Key words: phytolith, Poyang Lake, Holocene, climate evolution mechanism, East Asian Summer Monsoon

摘要：

鄱阳湖地处东亚季风活动频繁区,是全新世气候变化敏感地区之一。为了重建鄱阳湖地区近5700年以来的气候演化过程并讨论其气候演化机制,以鄱阳湖ZK01钻孔内植硅体为指标,采用主成分分析方法与温暖指数划分出了3个主要的气候阶段,结果显示: (1)近5700年以来鄱阳湖地区出现了4次明显的相对干旱期和3次相对湿润期,植硅体记录对全球性事件识别较为敏感,例如4.2 ka事件和小冰期; (2)植硅体记录与响应东亚夏季风变化的石笋 δ¹⁸O 记录存在较好的对应关系,东亚夏季风强度减弱时鄱阳湖地区气候较湿润,反之则较干旱; (3)位于东亚季风区南部的鄱阳湖植硅体记录同指示降水变化的华北岱海地区树木花粉记录间具有一定可比性,显示出在中晚全新世中国东部季风区的南北方也存在反位相的降水空间格局; (4)ENSO活动对中全新世以来的鄱阳湖地区水文气候具有一定的影响,ENSO事件强度增加时期多对应着鄱阳湖气候湿润期,而ENSO事件的强度变化可能代表厄尔尼诺或拉尼娜的强度变化。

关键词: 植硅体, 鄱阳湖, 全新世, 气候演化机制, 东亚夏季风

CLC Number: 

• P534.63+2