: Comprehensive studies on a stalagmite from the Panlong cave, Guilin, have shown that the isotopic records and sedimentary characteristics can reflect the changes of both palaeotemperatures and palaeorainfall, that i...: Comprehensive studies on a stalagmite from the Panlong cave, Guilin, have shown that the isotopic records and sedimentary characteristics can reflect the changes of both palaeotemperatures and palaeorainfall, that is to say, it is possible to get some information about the changes in climate of the area from the speleothem. The results suggest that: (1) the Younger Dryas event might have persisted in the area from 11 300 to 10 800 a B.P.; (2) from 9000 to 7000 a B.P., the climate got warmer and wetter, and the summer monsoon was gradually enhanced; (3) from 7000 to 4500 a B.P., the climate was warm and wet, and the summer monsoon prevailed; and (4) from 4500 a B.P. on, the summer monsoon was weakened and the modern climate pattern appeared, but there were several cold and dry periods, namely, from 4000 to 2500 a B.P., ca. 2400 a B.P. and < 1000 a B.P.展开更多
The stalagmite δ18O record is known to be associated with the climate, but the specifics of the relationship remain unclear. It may not represent variation in air temperature or precipitation, but instead reflect int...The stalagmite δ18O record is known to be associated with the climate, but the specifics of the relationship remain unclear. It may not represent variation in air temperature or precipitation, but instead reflect integral changes of monsoon circulation, especially water vapor sources(the so-called "circulation effect"). Since large-scale atmospheric-oceanic modes such as the Atlantic Multidecadal Oscillation(AMO), Pacific Decadal Oscillation(PDO), and North Atlantic Oscillation(NAO) exert significant effects on Asian monsoon, in this paper the authors investigate the relationships of the East Asian stalagmite δ18O record with these modes. The last three centuries form the focus of our study, for which the authors use reconstructed as well as instrumental data. Considering the impacts of human activity, our analysis is conducted with respect to two periods—the pre- and post-industrial periods. The results show significant lead-lag connections: a positive correlation peaks when the PDO leads East Asian stalagmite δ18O by 3 years, which is persistent over the past 300 years; while the relationships of the AMO and NAO with the East Asian stalagmite δ18O record show significant differences in the post-industrial relative to the pre-industrial period. This implies that the East Asian stalagmite δ18O record may primarily reflect the PDO signal.展开更多
In this paper the authors report a preliminary study on a Holocene stalagmite from Shihua Cave in Southwest Beijing.The result shows that the thickness of annual growth layers which is defined by annual deposit hiatus...In this paper the authors report a preliminary study on a Holocene stalagmite from Shihua Cave in Southwest Beijing.The result shows that the thickness of annual growth layers which is defined by annual deposit hiatuses preserve changes with precipitation. In light with the thickness of annual layers the authors reconstruct the climatic variation history of the last 2300 years in Beijing area.The climatic patterns seems to reappear irregularly on millennium to decade scales in the last 1000 years. The stable isotopic sequence interprets that the climate and environment in Beijing could be separated into two stages in the late Holocene: the monsoon was strong and the environment was wet in the former stage and in the latter stage the monsoon was weak and the environment was dry. The annual layers and oxygen isotope could be taken as natural signals and carbon isotope as a comprehensive signal containing the natural information and the information of anthropogenic activity.展开更多
Spelean stalagmite dating using thermal ionization mass spectrometry (TIMS) on the basis of U Th disequilibrium has contributed greatly to paleoclimatology, paleo environment, paleo oceanology, archaeology as well as ...Spelean stalagmite dating using thermal ionization mass spectrometry (TIMS) on the basis of U Th disequilibrium has contributed greatly to paleoclimatology, paleo environment, paleo oceanology, archaeology as well as modern volcano magmatism studies. Results of our studies on stalagmite chronology are also reported in this paper.展开更多
The discovery of abrupt paleo\|climate change events and the prediction of environmental changes in the future time have raised an urgent request for high\|resolution paleo\|environmental records. This paper reviews t...The discovery of abrupt paleo\|climate change events and the prediction of environmental changes in the future time have raised an urgent request for high\|resolution paleo\|environmental records. This paper reviews the progress made in chronology and paleo\|environment of stalagmites from karst caves in China and presents some of the results of TIMS\|U\|series dating of stalagmites composed of secondary carbonates, taken from the Dongge, Longquan and Yamen karst caves in Libo County and the Qixing karst cave in Duyun, Guizhou Province, on a MAT\|262 mass spectrometer.展开更多
A method for determining Mg/Ca of stalagmite by LA-MC-ICPMS is studied. 24Mg/44Ca (Mass 22, intensity of 44Ca2+ , collected by ion counting and mass 24, intensity of 24Mg+, collected by Faraday cup) ratios were measur...A method for determining Mg/Ca of stalagmite by LA-MC-ICPMS is studied. 24Mg/44Ca (Mass 22, intensity of 44Ca2+ , collected by ion counting and mass 24, intensity of 24Mg+, collected by Faraday cup) ratios were measured in replace of Mg/Ca ratios. Both diameter of laser sampling spot and laser moving increment were 20 μm. The curve of Mg/Ca vs. distance directly was obtained. The result indicates that relative Mg/Ca ratios changed from 0.5 to 2.0 in this stalagmite and it is enough to reflect environmental factors act.展开更多
据南京汤山葫芦洞石笋的23个热电离质谱测年结果和分辨率达100～200 a的氧、碳稳定同位素测试数据,讨论了75～35 ka BP期间东亚季风气候的高频振荡特征。石笋氧同位素值的波动范围介于-9.165‰～-5.456‰之间,相邻峰谷的变幅可达2‰～3...据南京汤山葫芦洞石笋的23个热电离质谱测年结果和分辨率达100～200 a的氧、碳稳定同位素测试数据,讨论了75～35 ka BP期间东亚季风气候的高频振荡特征。石笋氧同位素值的波动范围介于-9.165‰～-5.456‰之间,相邻峰谷的变幅可达2‰～3‰,由其构成的16个气候不稳定性事件与格陵兰冰心δ^(18)O记录中IS8～IS20和北大西洋冰漂碎屑事件H4～H6有良好的对比关系,揭示了东亚季风气候变化与高纬极地大气温度变化存在着动力机制上的联系。石笋碳同位素记录呈现类似于δ^(18)O记录的高频振荡形式,反映了洞穴上覆植被类型对气候变化的快速响应。石笋稳定同位素曲线上72 ka BP左右的快速降温事件与印度尼西亚 Toba火山喷发事件基本一致,有可能说明晚更新世全球气候事件的发生并非单一源于北大西洋深层水体的变化。展开更多
文摘: Comprehensive studies on a stalagmite from the Panlong cave, Guilin, have shown that the isotopic records and sedimentary characteristics can reflect the changes of both palaeotemperatures and palaeorainfall, that is to say, it is possible to get some information about the changes in climate of the area from the speleothem. The results suggest that: (1) the Younger Dryas event might have persisted in the area from 11 300 to 10 800 a B.P.; (2) from 9000 to 7000 a B.P., the climate got warmer and wetter, and the summer monsoon was gradually enhanced; (3) from 7000 to 4500 a B.P., the climate was warm and wet, and the summer monsoon prevailed; and (4) from 4500 a B.P. on, the summer monsoon was weakened and the modern climate pattern appeared, but there were several cold and dry periods, namely, from 4000 to 2500 a B.P., ca. 2400 a B.P. and < 1000 a B.P.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA11010401)the National Natural Science Foundation of China (Grant No. NSFC41375085)
文摘The stalagmite δ18O record is known to be associated with the climate, but the specifics of the relationship remain unclear. It may not represent variation in air temperature or precipitation, but instead reflect integral changes of monsoon circulation, especially water vapor sources(the so-called "circulation effect"). Since large-scale atmospheric-oceanic modes such as the Atlantic Multidecadal Oscillation(AMO), Pacific Decadal Oscillation(PDO), and North Atlantic Oscillation(NAO) exert significant effects on Asian monsoon, in this paper the authors investigate the relationships of the East Asian stalagmite δ18O record with these modes. The last three centuries form the focus of our study, for which the authors use reconstructed as well as instrumental data. Considering the impacts of human activity, our analysis is conducted with respect to two periods—the pre- and post-industrial periods. The results show significant lead-lag connections: a positive correlation peaks when the PDO leads East Asian stalagmite δ18O by 3 years, which is persistent over the past 300 years; while the relationships of the AMO and NAO with the East Asian stalagmite δ18O record show significant differences in the post-industrial relative to the pre-industrial period. This implies that the East Asian stalagmite δ18O record may primarily reflect the PDO signal.
文摘In this paper the authors report a preliminary study on a Holocene stalagmite from Shihua Cave in Southwest Beijing.The result shows that the thickness of annual growth layers which is defined by annual deposit hiatuses preserve changes with precipitation. In light with the thickness of annual layers the authors reconstruct the climatic variation history of the last 2300 years in Beijing area.The climatic patterns seems to reappear irregularly on millennium to decade scales in the last 1000 years. The stable isotopic sequence interprets that the climate and environment in Beijing could be separated into two stages in the late Holocene: the monsoon was strong and the environment was wet in the former stage and in the latter stage the monsoon was weak and the environment was dry. The annual layers and oxygen isotope could be taken as natural signals and carbon isotope as a comprehensive signal containing the natural information and the information of anthropogenic activity.
文摘Spelean stalagmite dating using thermal ionization mass spectrometry (TIMS) on the basis of U Th disequilibrium has contributed greatly to paleoclimatology, paleo environment, paleo oceanology, archaeology as well as modern volcano magmatism studies. Results of our studies on stalagmite chronology are also reported in this paper.
文摘The discovery of abrupt paleo\|climate change events and the prediction of environmental changes in the future time have raised an urgent request for high\|resolution paleo\|environmental records. This paper reviews the progress made in chronology and paleo\|environment of stalagmites from karst caves in China and presents some of the results of TIMS\|U\|series dating of stalagmites composed of secondary carbonates, taken from the Dongge, Longquan and Yamen karst caves in Libo County and the Qixing karst cave in Duyun, Guizhou Province, on a MAT\|262 mass spectrometer.
文摘A method for determining Mg/Ca of stalagmite by LA-MC-ICPMS is studied. 24Mg/44Ca (Mass 22, intensity of 44Ca2+ , collected by ion counting and mass 24, intensity of 24Mg+, collected by Faraday cup) ratios were measured in replace of Mg/Ca ratios. Both diameter of laser sampling spot and laser moving increment were 20 μm. The curve of Mg/Ca vs. distance directly was obtained. The result indicates that relative Mg/Ca ratios changed from 0.5 to 2.0 in this stalagmite and it is enough to reflect environmental factors act.
文摘据南京汤山葫芦洞石笋的23个热电离质谱测年结果和分辨率达100～200 a的氧、碳稳定同位素测试数据,讨论了75～35 ka BP期间东亚季风气候的高频振荡特征。石笋氧同位素值的波动范围介于-9.165‰～-5.456‰之间,相邻峰谷的变幅可达2‰～3‰,由其构成的16个气候不稳定性事件与格陵兰冰心δ^(18)O记录中IS8～IS20和北大西洋冰漂碎屑事件H4～H6有良好的对比关系,揭示了东亚季风气候变化与高纬极地大气温度变化存在着动力机制上的联系。石笋碳同位素记录呈现类似于δ^(18)O记录的高频振荡形式,反映了洞穴上覆植被类型对气候变化的快速响应。石笋稳定同位素曲线上72 ka BP左右的快速降温事件与印度尼西亚 Toba火山喷发事件基本一致,有可能说明晚更新世全球气候事件的发生并非单一源于北大西洋深层水体的变化。
