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基于湖北神农架地区石笋(SB25)6个230Th年龄和472个氧同位素分析,获得了133~127ka时期十年际分辨率的δ18O时间序列.该石笋δ18O时间序列记录了倒二冰期向末次间冰期转换时东亚夏季风降水强度变化的详细过程.通过对石笋的精确定年,确定终止点Ⅱ的年龄为129.5±1.0ka,证实了北半球太阳辐射是东亚季风冰期/间冰期转换的主要驱动力.该石笋δ18O值在冰期/间冰期旋回中振荡幅度达4‰左右,这在亚洲季风区洞穴记录中具有普遍性.分辨率为十年际的δ18O曲线显示东亚季风在倒二冰期向末次间冰期转换时表现为4个阶梯式阶段,其中“终止点Ⅱ停滞”后的季风降水突增与全球CH4浓度突变同步.
Based on 6 230Th ages and 472 oxygen isotope analyzes of stalagmite (SB25) in Shennongjia area of Hubei Province, a δ18O time series with decadal resolution of 133 ~ 127 ka was obtained. The stalagmite δ18O time series records the transition from the last ice period to the last interglacial period The detailed process of the change of the intensity of the East Asian summer monsoon rainfall is confirmed by the precise dating of the stalagmite and the age of the termination point Ⅱ is 129.5 ± 1.0 ka, confirming that the solar radiation in the northern hemisphere is the main driving force for the conversion of the East Asian monsoon glacial / interglacial period. The δ18O value oscillates about 4 ‰ in the glacial / interglacial cycles, which is common in the Asian monsoon cave records. The decadal δ18O curve shows that the East Asian monsoon converted to the last interglacial during the second ice age The results show that there are four stepwise stages, in which sudden increase of monsoon rainfall after “stop point Ⅱ” stagnates synchronously with global CH4 concentration abrupt change.