| 湖北神农架石笋年纹层与氧碳同位素关系 |
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| 引用本文： | 梁燕,孔兴功,汪永进.湖北神农架石笋年纹层与氧碳同位素关系[J].中国岩溶,2008,27(4):371-376. |
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| 作者姓名： | 梁燕 孔兴功 汪永进 |
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| 作者单位： | 南京师范大学地理科学学院 |
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| 摘 要： | 基于湖北神农架青天洞石笋U 系测年和年纹层统计结果,分别建立了末次盛冰期( 17 474± 174～ 16 105± 151 aB. P. )和全新世大暖期( 6 935. 4± 33. 8～6 137± 48 aB. P. )长达1 000余年的两个石笋年纹层生长序列。全新世大暖期年纹层平均厚度( 265μm) 约为末次盛冰期( 102μm)的2. 5倍,说明在间冰期东亚季风增强时石笋沉积速率较大,冰期时则相反。两支分辨率为4～ 8年的石笋年纹层厚度与δ13 C变化曲线对比显示: 在百年尺度上,石笋年纹层厚度与δ13 C变化曲线均呈良好的相关性(相关系数分别为- 0. 53和- 0.60) ,说明两指标可能受洞穴上覆土壤带CO2 产率这一主控因素的影响。当上覆土壤层生物活动增强, CO2 分压较高时,导致石笋δ13 C值偏负、生长速率增大。然而,在相同尺度上,两支石笋δ18O变化与对应的δ13 C及年纹层厚度之间的相关性较弱,反映研究地点上覆土壤层CO2产率对东亚夏季风强弱变化响应关系比较复杂。
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| 关 键 词： | 石笋 年纹层厚度 氧、碳同位素 生长速率 湖北神农架 |
The relationship between annual laminae and stable isotopes in two stalagmites in Shennongjia, Hubei |
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| LIANG Yan,KONG Xing-gong and WANG Yong-jin.The relationship between annual laminae and stable isotopes in two stalagmites in Shennongjia, Hubei[J].Carsologica Sinica,2008,27(4):371-376. |
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| Authors: | LIANG Yan KONG Xing-gong and WANG Yong-jin |
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| Institution: | College of Geography Science, Nanjing Normal University |
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| Abstract: | Two laminar sequences are reconstructed during the Last Glacial Maximum （17 000-16 000a B. P. ） and the Holocene Optimum （7 000-6 000a B. P. ） from two independently-dated and annual-counted stalagmites from Qingtian cave, Shennongjia, Hubei. The mean thickness of the bands during the Holocene Optimum （265μm） ranges twice of that during the LGM （102μm）, which indicates strong East Asian summer monsoon may be beneficial for the growth of the stalagmite. A comparison between δ^18O, δ^13C and annual layer thickness reveals that the band thickness from two stalagmites displays a distinctly negative correlation with δ^13C profiles （r=-0. 53 and -0.60, respectively） on centennial scale. This suggests that both of them are likely modulated by the rate of CO2 production in soil associated with plant respiration and microbiologically induced organic matter decomposition. Increased soil respiration leads to higher soil Pco2 and consequently more negative δ^13C values of soil CO2 and a larger growth rate. However, δ^18O profile shows slight correlation with those of δ^13C and laminar thickness, which implies weak correlation with the CO2 production rate in soil resulted from East Asian summer monsoon. |
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| Keywords: | stalagmites laminar thickness δ^18O δ^13C growth rate Shennongjia Hubei |
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