Implications of stalagmite density for past climate change:An example from stalagmite growth during the last deglaciation from Wanxiang Cave,western Loess Plateau  

作　　者：ZHANG DeZhong ZHANG PingZhong SANG WenCui CHENG Hai WU XiuPing YUAN Ye BAI YiJun WANG JiangLin JIA JiHong 

机构地区：[1]Key Laboratory of Western China's Environmental System of Ministry of Education, College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, China [2]Institute of Global Environmental Change, Xi'an Jiaotong University, Xi'an 710049, China [3]Department of Geology and Geophysics, University of Minnesota, Minneapolis, MN 55455, USA

出　　处：《Chinese Science Bulletin》2010年第34期3936-3943,共8页

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)

摘　　要：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.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 deglaeiation. Over long timescales, high-precision 23~Th 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 580 record which reflects Asian monsoon intensity. Strengthening/weakening （lighter/heavier stalagmite odSO 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-Allerod Cold Period （1ACP）, Older Dryas （OD） and Inter-Bolling 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.

关 键 词：石笋记录 记录密度 黄土高原西部 末次冰消期 HEINRICH事件 气候变化 笋生长 方解石晶体 

分 类 号：P532[天文地球—古生物学与地层学] TP333.4[天文地球—地质学]