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基于210Pb和230Th两种定年方法,并结合黄龙洞石笋δ18O测试数据建立了青藏高原东部近半个世纪以来平均分辨率达到年际的亚洲季风变化序列.通过对黄龙洞石笋氧同位素体系的研究,表明现代洞穴滴水与洞穴周围大气降水的氧同位素具有一致性,石笋方解石与洞穴滴水是在同位素平衡分馏状态下沉积的.与器测数据对比分析发现,黄龙洞石笋δ18O的轻重变化主要受西南季风(印度季风)带来的降水量效应所控制,受温度的影响比较弱.石笋δ18O在短时间尺度上的轻重变化主要反映了季风降水δ18O的信息,指示了西南季风的年际变化.最近50a来,四川黄龙洞石笋的氧同位素组成具有逐渐变重的趋势,即逐渐变得相对富集18O,与亚洲季风区其他石笋δ18O具有相同的变化趋势,而且也与东亚、南亚季风指数所指示的季风减弱趋势相一致,与全球季风指数密切相关.这种亚洲季风的减弱趋势主要受太阳辐射变化的影响,并紧密地匹配于高空平流层的温度变化.
Based on the 210Pb and 230Th dating methods and the δ18O test data of stalagmite in Huanglong Cave, the Asian monsoon series with average resolution reaching the interannual annual average over the past half century in the eastern Tibetan Plateau was established. By studying the oxygen isotopic composition of stalagmite in Huanglong Cave, It shows that the isotopes of calcite and cave drip of stalagmite and cave are deposited under isotopic equilibrium fractionation.Comparing with the measured data, it is found that the change of δ18O in stalagmite of Huanglong Cave is mainly affected by the southwest monsoon (Indian monsoon), and the influence of temperature is relatively weak.The variation of δ18O in stalagmite on a short time scale mainly reflects the information of δ18O in monsoon precipitation, and indicates the interannual variation of southwest monsoon in recent 50 years , The oxygen isotopic composition of the stalagmite in Huanglong Cave of Sichuan Province shows a trend of gradually becoming heavier, ie gradually becoming relatively enriched 18O, showing the same trend with other stalagmites δ18O in the Asian monsoon region, but also similar to those indicated by the East Asian and South Asian monsoon indices The monsoon weakening trend is consistent with the global monsoon index is closely related to the reduction of this Asian monsoon Trend is mainly affected by changes in solar radiation, and closely matched to the temperature change altitude in the stratosphere.