神农架140~124 kaBP百年尺度东亚季风降水的石笋记录

CENTENNIAL-SCALE EAST ASIAN MONSOON PRECIPITATION RECORD OVER 140~124 kaBP FROM A STALAGMITE IN SHENNONGJIA

  • 摘要: 基于神农架山宝洞SB28石笋230Th年龄和氧同位素数据,建立了140~124 kaBP百年尺度的东亚季风降水序列,其长期演化趋势与北纬33°夏季日辐射能量曲线基本一致。山宝洞SB28石笋与董哥洞D4石笋δ18O曲线呈现出整体一致的特征,证实了亚洲季风降水同位素组成变化具有广泛的区域意义。末次间冰期129.5~124.3 kaBP季风降水具有百年尺度高频振荡特征,功率谱分析周期有525、228和207 a,类似于全新世大气△14C残差百年尺度周期,表明末次间冰期亚洲季风强度的变化仍然受太阳活动的影响。在倒数第二次冰期向末次间冰期转换时,北半球太阳辐射可能触发了全球末次间冰期全盛期的开始。

     

    Abstract: 230Th ages and oxygen isotope data of a stalagmite from Shanbao Cave in Hubei Province characterize the East Asian Monsoon precipitation from 140 to 124 kaBP. The record broadly follows 33°N summer insolation. Similar changing trend was observed in the two δ18O curves derived from the Shanbao Cave and Dongge Cave, which proved the changes of the oxygen composition of the Asian Monsoon precipitation have the generally regional meanings. During the Last Interglacial period (129.5~124.3 kaBP), SB28 δ18O record shows high frequency fluctuation. Power spectral analysis of the record shows statistically significant centennial periodicities centered on 525, 228 and 207 a. These periodicities are close to significant periods of the △14C record, indicating that solar changes are also responsible for changes of Asian Monsoon intensity. During the transition from the Penultimate Glaciation to the Last Interglaciation, the North Hemisphere insolation possible triggers the inception of full interglacial conditions worldwide.

     

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