公元8世纪以来贵州荔波石笋高分辨率的气候变化记录

通过中国贵州荔波龙泉洞L1及L2两根石笋19件ICPMS230 Th测年和459件氧稳定同位素分析, L1时限范围为918-1910aA. D. , L2为724-1888aA. D. ;稳定同位素样品的平均分辨率分别为6. 6a和3. 6a。两根石笋δ18O记录取得了平行一致的结果,石笋记录可分为3个气候期,即: 中世纪冷期(公元8世纪- 995aA.D. ) ,石笋δ18O总的偏重,变化幅度较小,最轻为- 8. 84‰ ,最重为- 6. 72‰ ,平均值为- 7. 76‰ ;中世纪暖期( 995- 1340a A. D. ) ,石笋记录为两峰夹一谷, 200年级的一个半旋回,δ18O最轻为- 9. 47‰ ,最重为- 6. 58‰ ,平均值为- 7. 94‰ ;小冰期( 1340- 1880aA. D. ) ,石笋记录为四谷三峰相间交替,即季风表现出由弱到强的200年级3个半旋回,δ18O最轻为- 9. 50‰ ,最重为- 6. 07‰ ,平均值与中世纪暖期基本一致,为- 7. 92‰ ,但变化幅度要大一些,特别是弱季风期要偏重一些。L1及L2两石笋δ18O记录可以很好地和中国中东部物候记录对比。在总体变化格局上也可以和格陵兰冰芯记录进行对比。石笋记录也可以与宇宙核素产率及太阳耀斑记录进行对比,小冰期中石笋δ18O记录的4个低谷期(弱季风期) ,正好与宇宙核素产率及太阳耀斑曲线的低谷区相对应,并分别可以和太阳黑子1810年达尔顿极小值、1645- 1715年蒙德极小值1420- 1530年的斯波瑞尔极小值、1280- 1440年的沃尔夫极小值一一对应。太阳黑子的变化,直接改变地球接受太阳辐射能量的变化,说明低纬度地区短尺度季风气候直接响应于太阳辐射能量的变化。 

High resolution stalagmite records of climate change since 800a A. D. in Libo, Guizhou

Stalagmite L1 and stalagmite L2 from Longquan cave （N25°29′ ,E107°52′ ,550m altitude） at Libo, Guizhou are 50cm and 192cm high respectively. On the basis of 19 ICPMS ^230Th ages and 459 stable oxygencarbon isotope samples analysis, it proves that the stalagmite L1＇s time range is from 918a A. D. to 1910a A. D. and the stalagmite L2 is from 724a A.D. to 1888a A. D.. The stable isotope average resolution of the stalagmite L1 and stalagmite L2 are 6.6a and 3.6a respectively. The records of δ^18O from the two stalagmite are coherent, which can be divided into three climatic periods： （1） Medieval cold period （724-995 a A. D. ）. During this period,δ^18O of the stalagmite becomes heavier but the change scope is small, and the lightest value of oxygen isotope is -8.84‰ ,the heaviest value is -6.72‰ and the average is -7.76‰ which is 0.16‰ heavier than the average value of the two stalagmite （-7.92‰） ; （2）Medieval warm period（995-1340 a A. D. ）. It is recorded by stable oxygen isotope in the shape of two wave crest and one trough which form half a 200-year gyration, corresponding to two strong monsoon periods and one relative weak monsoon period. And the lightest value of oxygen stable isotope is -9. 47‰, the heaviest -6. 58‰ and the average -7. 94‰; （3） Small ice age（1340-1880 a A. D. ）. This climatic period is recorded by stalagmite in the form of three wave crests and four troughs alternately that indicates 3 and half a 200-year monsoon gyration. In this climatic period, the lightest value of stable oxygen isotope is -9.50‰, the heaviest -6.07‰ and the average -7. 92‰ which is larger than that of the medieval warm period and furthermore, fluctuating range of stable oxygen isotope is bigger than that of medieval warm period, especially in weak monsoon period. The stable oxygen isotope records from stalagmite L1 and stalagmite L2 parallels phonological records in east China well. As a whole, the change pattern of stalagmites can parallel records in the Gre