青藏高原东部若尔盖盆地泥炭发育记录的全新世气候突变

Abrupt climatic changes in the Holocene recorded by the history of peat formation in ZoigéBasin on the eastern Tibetan Plateau

青藏高原东部若尔盖盆地泥炭沉积可提供具有可靠年代控制与高分辨率的古气候记录。本研究利用若尔盖泥炭沉积核心区的3个泥炭钻孔,开展了10~20年高分辨率的烧失量分析,重建出高原东部全新世泥炭发育过程及其记录的气候突变事件。研究结果显示,青藏高原东部早、中全新世(约11.5~6.0 ka)气候暖湿适宜,泥炭发育繁盛;之后气候趋向相对冷干,泥炭发育缓慢;泥炭指标序列的主导准周期显示出与太阳辐射和季风变化2000年与1500年周期特征的较好对应关系。研究结果揭示了青藏高原东部全新世气候与生态环境的长期变化受到了太阳辐射与印度季风降水的主要驱动,气候突变事件则反映了来自太阳活动及北半球高纬温度异常的调制作用。

In this study,the history of peat formation and abrupt climate changes during the Holocene were reconstructed by using the loss-on-ignition results of three peat cores(ZB08-C1:33°27'N,102°38'E,at 3467 m a.s.l.,length of 6.5 m;ZB10-C9:32°47'N,102°31'E,3507 m a.s.l.,length of 6.68 m;ZB10-C14:33°06'N,102°40'E,3470 m a.s.l.,length of 8.9 m)in the ZoigéBasin(32°10'~34°10'N,101°45'~103°25'E;3400~3600 m a.s.l.)on the eastern Tibetan Plateau(TP).The results of loss-on-ignition analysis showed that local peatland initiated at around 11.5 ka,thrived during 11.5~6.0 ka under the climatic optimum in the Early to Middle Holocene,and then began to degrade when climate turned relatively cold and dry in the Late Holocene.Several abrupt climate changes were recovered,occurring at the cold/dry intervals of 11.2 ka、10.6~10.3 ka、9.6~9.4 ka and 1.6~1.4 ka,as well as the cold/wet intervals of 6.3~6.1 ka、5.5~5.3 ka、4.3~3.8 ka、3.1~2.8 ka、2.1 ka and 0.9~0.6 ka.Then,we used the spectral analysis and continuous wavelet transform to reveal the periodicity characteristics in the history of local peat formation.The quasi-periodicities imbedded in the peat-proxy sequences during the Holocene,which showed the dominating periodicities of ca.2000 and 1500 years,were close to the periodic behavior of the summer solar insolation and temperature anomalies in the North Atlantic.Therefore,it's suggested that the climate and ecosystem on the eastern TP during the Holocene should be mainly driven by the variations in solar insolation,Indian Summer Monsoon and monsoonal precipitation,and modulated by the periodic behavior of the solar activity and temperature anomalies in the high northern latitudes.