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亚洲季风区边缘甘肃武都万象洞一根石笋(WX42A)在末次冰消期不同生长时期密度变化表现出有规律的波动.高精度230Th测年和高分辨率的石笋密度结果表明,生长于17644～12758a BP之间石笋密度变化时间序列在长时间尺度上与反映亚洲季风强度变化的石笋δ18O记录变化趋势非常一致,显示出季风强度增强/减弱(δ18O值偏轻/偏重),石笋密度随之增大/减小的特征;在短时间尺度上石笋密度的降低也对应于一些季风减弱事件如Inter-Allerφd Cold Period(IACP)、Older Dryas(OD)和Inter-Bφlling Cold Period(IBCP).总体上,石笋密度的降低是对季风减弱、降水量减少造成洞穴滴水速率降低、结晶核减少和晶体增大、生物活动强度减弱和土壤CO2分压降低、碎屑杂质物质增多的反映.然而在季风极端减弱、降水量大幅度减少和生物活动强度减弱时期,温度的变化将主导石笋密度的变化,如在北大西洋H-1事件温度突然降低时,石笋密度却突然增大,这是由环境温度的突然降低使得少量下渗水在低温下溶解的碳酸氢钙浓度升高、溶液过饱和度升高而形成晶体规则紧密排列且密度较大的石笋矿物所造成的.这种灵敏记录石笋生长历史和外界环境变化的过去石笋密度随着时间波动,说明石笋密度在过去气候变化研究中具有极大的潜力.
At the edge of the Asian monsoon region, a stalagmite (WX42A) of WX42A in Wuwei Cave, Wudu, Gansu Province showed regular fluctuations in density during the last ice-age growth period.The results of high-precision 230Th dating and high-resolution stalagmite density show that the growth of WX42A, The time series of stalagmite density between ~ 12758a BP and the δ18O record of stalagmite reflecting the change of Asian monsoon intensity on a long time scale are consistent with each other, showing a monsoon intensity increase / decrease (δ18O value is too light / heavy) Increase / decrease; the decrease in stalagmite density on a short-term scale also corresponds to some monsoon weakening events such as Inter-Allerφd Cold Period (IACP), Older Dryas (OD) and Inter-Bφlling Cold Period (IBCP) , The decrease of stalagmite density is a reflection of the weakened monsoon and decrease of drip rate, crystal nucleus and crystal, decrease of biological activity intensity and decrease of partial pressure of CO2, Extremely weakening, a significant reduction in precipitation and a decrease in the intensity of biological activity, temperature changes will dominate the density of stalagmite changes, as in the North Atlantic H-1 Sudden drop in event temperature, the density of stalagmite suddenly increased, which is due to a sudden decrease in ambient temperature so that a small amount of infiltration water dissolved in low temperature increased the concentration of calcium bicarbonate, the solution supersaturation and the formation of crystal rules closely arranged Density of stalagmite minerals.This sensitive stalagmite growth history and changes in the external environment changes in the past stalagmite density over time, indicating that the stalagmite density in the past climate change research has great potential.