The density of a stalagmite(WX42A)from Wanxiang Cave,Wudu County,Gansu Province,China,in the western margin of the Asian summer monsoon region,presents regular fluctuations in different deposition periods during the l...The density of a stalagmite(WX42A)from Wanxiang Cave,Wudu County,Gansu Province,China,in the western margin of the Asian summer monsoon region,presents regular fluctuations in different deposition periods during the last deglaciation.Over long timescales,high-precision 230Th dating and high-resolution stalagmite density data indicate that the density-time series between 17644 a BP and 12758 a BP is quite similar to the stalagmite δ18O record which reflects Asian monsoon intensity.Strengthening/weakening(lighter/heavier stalagmite δ18O values)of the Asian monsoon is accompanied by increase/decrease in stalagmite density.Over short timescales,decrease in stalagmite density correlates to monsoon-retreat events such as the Inter-AllerФd Cold Period(IACP),Older Dryas(OD)and Inter-BФlling Cold Period(IBCP).Generally,this kind of decrease in stalagmite density reflects precipitation decrease with weakening of the Asian monsoon,which in turn slows cave dripwater rate and decreases crystal nuclei,leading to enlargement of calcite crystals,weakened biological activity and decreased soil pCO2 which increases the abundance of impure detrital materials in stalagmites.However,during the period of large amplitude reduction of precipitation and biological activity which resulted from extreme monsoon-retreat events,temperature variation would dominate fluctuation of stalagmite density.For example,stalagmite density increased suddenly when temperature dropped suddenly in the north Atlantic during Heinrich event 1(H-1).This may be caused by low seepage water temperature,more dissolved calcium carbonate,compact regular crystals forming under higher supersaturation,leading to the stalagmite increased density.Stalagmite density fluctuation sensitively recorded stalagmite growth history and environment,demonstrating that stalagmite density can be used as a proxy for paleoclimatic research.展开更多
位于青藏高原与黄土高原过渡带的甘肃武都万象洞石笋WXSM51和WXSM52提供了M IS 5(118~79kaB.P.)高分辨率的1δ8O记录。研究表明,万象洞石笋1δ8O值与夏季风强度呈负相关关系,与我国西南部的贵州董歌洞石笋1δ8O记录有良好的对应关系,并...位于青藏高原与黄土高原过渡带的甘肃武都万象洞石笋WXSM51和WXSM52提供了M IS 5(118~79kaB.P.)高分辨率的1δ8O记录。研究表明,万象洞石笋1δ8O值与夏季风强度呈负相关关系,与我国西南部的贵州董歌洞石笋1δ8O记录有良好的对应关系,并与高纬度的格陵兰NGR IP冰芯1δ8O记录和65°N太阳辐射强度有很好的一致性,说明万象洞石笋1δ8O记录了118~79kaB.P.期间亚洲季风强度的变化,同时也说明东亚季风强度的变化和全球气候变化同步,而且主要受控于北半球太阳辐射强度的变化。同时它与地中海碳酸盐记录有很好的相似性,和巴西石笋1δ8O记录在千年尺度上表现出相反的变化趋势,说明东亚季风区、地中海地区以及巴西季风区之间存在密切的联系,指示了南北半球气候在千年尺度上存在“跷跷板”(seesaw)现象。万象洞石笋1δ8O记录的M IS 5b与M IS 5 a突发性转换,与NGR IP冰芯1δ8O记录相似,而与神农架记录存在差异,说明万象洞地区对亚洲季风强度的响应更为敏感。展开更多
基金supported by the National Natural Science Foundation of China(40973007 and 40772110)the Specialized Research Fund for the Doctoral Program of Higher Education(200807300030)
文摘The density of a stalagmite(WX42A)from Wanxiang Cave,Wudu County,Gansu Province,China,in the western margin of the Asian summer monsoon region,presents regular fluctuations in different deposition periods during the last deglaciation.Over long timescales,high-precision 230Th dating and high-resolution stalagmite density data indicate that the density-time series between 17644 a BP and 12758 a BP is quite similar to the stalagmite δ18O record which reflects Asian monsoon intensity.Strengthening/weakening(lighter/heavier stalagmite δ18O values)of the Asian monsoon is accompanied by increase/decrease in stalagmite density.Over short timescales,decrease in stalagmite density correlates to monsoon-retreat events such as the Inter-AllerФd Cold Period(IACP),Older Dryas(OD)and Inter-BФlling Cold Period(IBCP).Generally,this kind of decrease in stalagmite density reflects precipitation decrease with weakening of the Asian monsoon,which in turn slows cave dripwater rate and decreases crystal nuclei,leading to enlargement of calcite crystals,weakened biological activity and decreased soil pCO2 which increases the abundance of impure detrital materials in stalagmites.However,during the period of large amplitude reduction of precipitation and biological activity which resulted from extreme monsoon-retreat events,temperature variation would dominate fluctuation of stalagmite density.For example,stalagmite density increased suddenly when temperature dropped suddenly in the north Atlantic during Heinrich event 1(H-1).This may be caused by low seepage water temperature,more dissolved calcium carbonate,compact regular crystals forming under higher supersaturation,leading to the stalagmite increased density.Stalagmite density fluctuation sensitively recorded stalagmite growth history and environment,demonstrating that stalagmite density can be used as a proxy for paleoclimatic research.
文摘位于青藏高原与黄土高原过渡带的甘肃武都万象洞石笋WXSM51和WXSM52提供了M IS 5(118~79kaB.P.)高分辨率的1δ8O记录。研究表明,万象洞石笋1δ8O值与夏季风强度呈负相关关系,与我国西南部的贵州董歌洞石笋1δ8O记录有良好的对应关系,并与高纬度的格陵兰NGR IP冰芯1δ8O记录和65°N太阳辐射强度有很好的一致性,说明万象洞石笋1δ8O记录了118~79kaB.P.期间亚洲季风强度的变化,同时也说明东亚季风强度的变化和全球气候变化同步,而且主要受控于北半球太阳辐射强度的变化。同时它与地中海碳酸盐记录有很好的相似性,和巴西石笋1δ8O记录在千年尺度上表现出相反的变化趋势,说明东亚季风区、地中海地区以及巴西季风区之间存在密切的联系,指示了南北半球气候在千年尺度上存在“跷跷板”(seesaw)现象。万象洞石笋1δ8O记录的M IS 5b与M IS 5 a突发性转换,与NGR IP冰芯1δ8O记录相似,而与神农架记录存在差异,说明万象洞地区对亚洲季风强度的响应更为敏感。
