辽宁本溪暖和洞早全新世石笋年纹层记录

EARLY HOLOCENE LAMINATED STALAGMITE RECORDS FROM NUANHE CAVE,BENXI,CHINA

  • 摘要: 据位于典型东亚季风区辽宁本溪暖和洞一支石笋(NH6)的年纹层计数并结合3个230Th年龄结果,建立了(8 630~7 050)±50 aBP期间连续发育近1 500 a的石笋年纹层厚度、灰度和氧同位素时间序列。研究石笋年纹层与北京石花洞和冰期南京葫芦洞在显微结构上相似,具有北方型石笋年层的年季旋回界面的基本特征,说明中国东部季风区石笋年层生长的气候控制因素特征明显。厚度与灰度在十年至百年际尺度旋回上呈现出整体一致的变化特征(相关系数r=0.56,n=1 580),反映了降水季节性反差较大条件下洞穴有机质等物质输入和滴水饱和度之间具有内在联系。两者的功率谱周期显示11~2 a共同成分,与现代季风降水周期吻合。年生长速率与氧同位素曲线的不一致,说明洞穴地点环境对大尺度季风气候的复杂响应。

     

    Abstract: A nearly 1 500-year time series inferred from annual layer thickness, gray level, and oxygen isotope variation during (8 630~7 050)±50 aBP has been established, with the support of three 230Th ages and annual layer-counting results of a stalagmite (No.NH6) from Nuanhe Cave in Benxi City of Liaoning. The similarity in microstructures of annual layer among NH6, Shihua Cave from Beijing and Glacial phase of Hulu Cave from Nanjing, and the diagnostic annual-seasonal cycling interfaces which is typical in northern China, suggest clearly that the annual growth of stalagmites is dominated by climatic factors in the monsoon zone of east China. The layer thickness and gray level vary synchronously in decadal-centennial scale (correlation coefficient r=0.56, n=1 580), indicates the inner relationship between incoming material (like organic substance and so on) and dropping-water saturation in the caves when precipitation changes dramatically in different seasons. Their power spectrum analysis show periodic changes of 2~11 years, which is coincide with modern monsoon precipitation change. The different variation history between annual growth rate and oxygen isotope, may be caused by the complicated mechanism when cave environment responsed to large scale monsoon climate.

     

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