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.
