57~48万年前东亚夏季风的神农架石笋记录

EAST ASIAN SUMMER MONSOON RECORD OVER 571~476 kaBP FROM A STALAGMITE IN SHENNONGJIA

  • 摘要: 应用MC-ICP-MS和MAT-253质谱技术,实测神农架山宝洞一支长达1.2 m石笋(SB32)的3个230Th年龄和236个氧同位素数据。在年龄误差范围内,运用天文轨道调谐方法重建了570~480 kaBP时段百年至千年际分辨率东亚夏季风降水记录。该记录跨越4个完整的岁差旋回,在岁差周期上石笋δ18O平均振幅达4‰。研究时段内东亚夏季风轨道尺度变化仍然受太阳辐射的控制。石笋记录的深海氧同位素阶段MIS14/13转换过程与末次冰消期具有类似特征。一系列千年尺度事件叠加在岁差周期夏季风变化趋势上,表明千年尺度气候变化是地球气候系统内部自我维持的固有频率,可能属于海-陆-气相互作用的结果。

     

    Abstract: Three 230Th dating results and 236 oxygen isotope data of a 1.2-m-long stalagmite were collected from Shanbao Cave in Shennongjia of Hubei Province. Within the dating uncertainty, an astronomical tuning was applied to reconstruct an East Asian summer monsoon history from 571 to 476 kaBP. Our record spans four precessional cycles, with an average amplitude of 4, which suggests East Asian monsoon variability was still paced by insolation in this period. A similar pattern to the last deglacial was found during the transition of MIS 14/13. A series of millennial climate events were superposed on the precessional trend of East Asian summer monsoon, indicating an inherent frequency self-sustained in the global climate system, which may be an interaction of ocean, land and atmosphere.

     

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