The isotope records which range from 3.9 kaBP to 15.7 kaBP with an average resolution of 90 a have been obtained from 45 cm to 193.6 cm of the upper part of D4 stalagmite from Dongguo Cave in Libo,Guizhou,by using sys...The isotope records which range from 3.9 kaBP to 15.7 kaBP with an average resolution of 90 a have been obtained from 45 cm to 193.6 cm of the upper part of D4 stalagmite from Dongguo Cave in Libo,Guizhou,by using system TIMS U-series dating and carbon and oxygen stable isotope analyses.The study indicates that the last cold event,the YD(Younger Dryas)event,of the last glacial period was apparently shown in D4 record,which started from 12.80 kaBP and ended in 11.58 kaBP,with a great range of drop in temperature.The end of the last glacial period was consistent with the termination I in oceanic isotope records and was with time limit of 11.3 kaBP.The three most distinct cold events in the early and middle Holocene occurred respectively in 10.91 kaBP,8.27 kaBP and 4.75 kaBP,with a range of drop in tem-perature reaching 2—5℃.The climate abrupt events in thousand and hundred years scale re-corded in stalagmiteδO can be compared to those in GISP2 ice cores from Greenland in their 18 happening time and the range of their lasting time.The cold events in 8.27 kaBP and 4.75 kaBP can also be compared to CC3 stalagmite records in Ireland,which indicate that climate changes of short range in China monsoon areas,western Europe and polar regions,have the same driv-ing factor.This has a global significance.In addition,the trend of record curves in some time-stages is apparently different,which reflects probably the difference between environment in monsoon climate areas and in polar regions.展开更多
Seven U-Th dates,560δ18O data and microscopic sequences were measured for sta-lagmites from two high-altitude caves in Shennongjia area,Hubei Province.Variations of the de-cadal-resolution stalagmiteδ18O record from...Seven U-Th dates,560δ18O data and microscopic sequences were measured for sta-lagmites from two high-altitude caves in Shennongjia area,Hubei Province.Variations of the de-cadal-resolution stalagmiteδ18O record from Swan Cave(1600 m elevation)reflect large spatial changes in circulation strength and precipitation of Asian monsoon.The evidence comes from a great similarity among the stalagmiteδ18O records from Nanjing,Jiangsu Province;Libo,Guizhou Province and here studied area during the last deglaciation,including a part interval of Younger-Dryas event and Bolling-Allerod.A 30-year-resolution stalagmiteδ18O record from Yongxing Cave(1400 m eleva-tion),70 km away from Swan Cave,reveals a rapid transition of Asian monsoon climate during Ter-mination 3 at about 245±5 kaBP.Based on 3 U-Th dates and about 5000 continuous annual bands,a millennial dry episode has been observed during Asian monsoonal Termination 3 from the Yongxingδ18O profile.With respect to its structure,duration and transition,the dry reversal,as indicated by our stalagmiteδ18O record,generally agrees with the pattern of the YD event well-expressed in the Chi-nese stalagmiteδ18O records.This YD-type event is characterized by a large decrease inδ18O value as much as 2.30‰,more than half of theδ18O excursion between glacial/interglacial periods,and lasts 1371±59 a determined by the annual counting chronology.After this event,the monsoon climate shifted abruptly into the interglacial period within 74±4 a.Our data corroborate the view that the re-peated occurrence of YD-type event was not an“accident”,possibly resulted from the coupling of ice-sheet and oceanic/atmospheric circulations.展开更多
基金supported by the National Naural Science F oundation of China(Gant Nos.40231008 and 40152002)a project of the Mimistry of Science amnd Techm logy ofChina(Grant No.2003DEB6J069).
文摘The isotope records which range from 3.9 kaBP to 15.7 kaBP with an average resolution of 90 a have been obtained from 45 cm to 193.6 cm of the upper part of D4 stalagmite from Dongguo Cave in Libo,Guizhou,by using system TIMS U-series dating and carbon and oxygen stable isotope analyses.The study indicates that the last cold event,the YD(Younger Dryas)event,of the last glacial period was apparently shown in D4 record,which started from 12.80 kaBP and ended in 11.58 kaBP,with a great range of drop in temperature.The end of the last glacial period was consistent with the termination I in oceanic isotope records and was with time limit of 11.3 kaBP.The three most distinct cold events in the early and middle Holocene occurred respectively in 10.91 kaBP,8.27 kaBP and 4.75 kaBP,with a range of drop in tem-perature reaching 2—5℃.The climate abrupt events in thousand and hundred years scale re-corded in stalagmiteδO can be compared to those in GISP2 ice cores from Greenland in their 18 happening time and the range of their lasting time.The cold events in 8.27 kaBP and 4.75 kaBP can also be compared to CC3 stalagmite records in Ireland,which indicate that climate changes of short range in China monsoon areas,western Europe and polar regions,have the same driv-ing factor.This has a global significance.In addition,the trend of record curves in some time-stages is apparently different,which reflects probably the difference between environment in monsoon climate areas and in polar regions.
基金This work was supported by the National Natural Science Foundation of China(Grant No.40225007)the Innovation Project in Graduate Education of Jiangsu Province.
文摘Seven U-Th dates,560δ18O data and microscopic sequences were measured for sta-lagmites from two high-altitude caves in Shennongjia area,Hubei Province.Variations of the de-cadal-resolution stalagmiteδ18O record from Swan Cave(1600 m elevation)reflect large spatial changes in circulation strength and precipitation of Asian monsoon.The evidence comes from a great similarity among the stalagmiteδ18O records from Nanjing,Jiangsu Province;Libo,Guizhou Province and here studied area during the last deglaciation,including a part interval of Younger-Dryas event and Bolling-Allerod.A 30-year-resolution stalagmiteδ18O record from Yongxing Cave(1400 m eleva-tion),70 km away from Swan Cave,reveals a rapid transition of Asian monsoon climate during Ter-mination 3 at about 245±5 kaBP.Based on 3 U-Th dates and about 5000 continuous annual bands,a millennial dry episode has been observed during Asian monsoonal Termination 3 from the Yongxingδ18O profile.With respect to its structure,duration and transition,the dry reversal,as indicated by our stalagmiteδ18O record,generally agrees with the pattern of the YD event well-expressed in the Chi-nese stalagmiteδ18O records.This YD-type event is characterized by a large decrease inδ18O value as much as 2.30‰,more than half of theδ18O excursion between glacial/interglacial periods,and lasts 1371±59 a determined by the annual counting chronology.After this event,the monsoon climate shifted abruptly into the interglacial period within 74±4 a.Our data corroborate the view that the re-peated occurrence of YD-type event was not an“accident”,possibly resulted from the coupling of ice-sheet and oceanic/atmospheric circulations.
