贵州白骨洞石笋记录的全新世季风气候演化与突变

EVOLUTION AND ABRUPT CHANGES OF THE HOLOCENE ASIAN MONSOON CLIMATE RECORDED BY STALAGMITE IN BAIGU CAVE IN GUIZHOU

  • 摘要: 通过对贵州白骨洞BG1石笋13个230Th年龄的测试和390个氧同位素数据的分析,建立了12.8~3.3 kaBP数十年尺度的亚洲季风降水序列,其长期演化趋势与北纬33°夏季日辐射能量曲线基本一致。石笋δ18O记录指示10.5~5.8 kaBP为本区气候湿润期,此后进入季风降水衰退期。在12.8~10.1 kaBP时段,平均分辨率为37 a的石笋降水记录与格陵兰冰心气温记录具有良好对应关系:(1)两者在新仙女木事件(YD)的变化细节及突变特征上表现出良好的一致性;(2)由YD事件向全新世转换的过程中两者都表现为3个阶梯式上升阶段,这种一致性有可能说明热带海气耦合驱动了北半球气候突变事件。在7.0~3.3 kaBP时段,平均分辨率为15 a的石笋δ18O序列记录了5次较为显著的降水减少期,可分别对应于冰心记录中的5个冷事件,高低纬气候的相似性可部分归因于太阳活动的影响。

     

    Abstract: A Holocene speleothem δ18O time series was reconstructed based on 390 stable isotope data and 13 230Th dates, covering a period from 12.8 to 3.3 kaBP. This record, with an average decadal-scale resolution, well reflects Asian summer monsoon history and thus its precipitation. A long-term trend of stalagmite δ18O profile bears a high similarity to the summer insolation at 33°N, suggesting that changes in solar irradiation forced the Holocene monsoon circulation during the entire Holocene period. We identified three stages from the stalagmite δ18O record, i.e. a transition of YD/Holocene at about 11ka, a humid stage during 10.5~5.8 kaBP and a gradually decreased monsoon precipitation stage since 5.8 kaBP. During the early Holocene,stalagmite δ18O record of an average 37-year resolution correlates well with the Greenland temperature record. Firstly, the two records show a similar detailed internal oscillation in YD event and abrupt changes out of YD event. Secondly, during the transition of YD event/Holocene period, three stepwise stages can be recognized in both of the records. Such coherence may suggest that the abrupt climate events in Northern Hemisphere were triggered by the coupled tropical ocean-atmosphere. During 7.0~3.3 kaBP, the stalagmite δ18O record, with a resolution of 15 years, displays a centennial-scale variability of monsoon precipitation. Among these, five weak monsoon events with a pace of 500~1000 years, can be related to, within the uncertainty of U/Th dates, five cold events recorded in Greenland ice core respectively. The inherent link between the high and low latitude climates can, in part, be ascribed to responses to changes of solar activity.

     

/

返回文章
返回