摘要:
由于深海氧同位素阶段5时期(Marine Isotope Stage 5,MIS 5)高分辨率的亚洲夏季风记录较少,限制了对该时期亚洲夏季风变化的认识.本文利用重庆金佛山羊口洞石笋的δ18 O记录,重建了MIS 5a/5b时期平均分辨率为38年的亚洲夏季风演变历史.发现该时段亚洲夏季风在千年—百年尺度上与北大西洋地区气候变化存在紧密联系.得益于误差小于0.4%的230Th测年结果,本文标定了中国间冰阶(Chinese Intersta dial,CIS)21的开始时间为84.6±0.3 ka BP,CIS 22的起止时间分别为91.2±0.3 ka BP和88.9±0.3 ka BP.此外,羊口洞石笋记录的CIS 21和CIS 22的变化模式与格陵兰记录不同,而与南极冰芯记录呈反相对应,可能表示在此阶段亚洲夏季风受到了南半球气候变化的影响.
Abstract:
Due to the paucity of the high-resolution records of the Asian summer monsoon (ASM) during the marine isotope stage (MIS) 5,our understanding about the ASM in this period is limited.In this study,a 38 -yr resolution stalagmite oxygen isotope record from the Yangkou Cave,Chongqing,southwestern China,is used to reconstruct the detailed evolution of the ASM during the period of MIS 5a/5b.The Yangkou record exhibits a close correlation between the ASM and the climate of the North Atlantic at a centennial-millennial-scale.In terms of the precise 230Th dating with error less than 0.4%,the onset and termination of Chinese Interstadial (CIS) 22 are constrained to 91.2±0.3 ka BP and 88.9±0.3 ka BP,respectively,and the beginning of the CIS 21 is defined at 84.6±0.3 ka BP.In addition,the evolution pattern of CIS 22 and CIS 21 recorded in the stalagmite from the Yangkou Cave is slightly different from those recorded in NGRIP,which is anti-phased with the trend of temperature change in the Antarctica.We speculate that the ASM during MIS 5a/5b may be affected by climate variation in the southern hemisphere.
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