对临汾盆地丁村剖面进行光释光测年,利用粒度年龄模型重建该地区的年代序列,对比分析粒度、频率磁化率和色度等气候代用指标,旨在反映千年尺度气候突变事件在临汾盆地的表现和区域性特征,揭示了东亚季风区末次冰期以来的气候不稳定性与...对临汾盆地丁村剖面进行光释光测年,利用粒度年龄模型重建该地区的年代序列,对比分析粒度、频率磁化率和色度等气候代用指标,旨在反映千年尺度气候突变事件在临汾盆地的表现和区域性特征,揭示了东亚季风区末次冰期以来的气候不稳定性与北大西洋地区存在的联系。结果表明:(1)丁村剖面中值粒径和频率磁化率曲线清晰地记录了80~20 ka BP间的5次Heinrich事件和19次Dansgaard-Oeschger(D-O)旋回,其中,H2和H6事件变化幅度最大,信号变化最明显,H5事件次之,H3和H4事件最小,反映了该地气候不仅受大尺度范围气候变化的控制,还受区域气候变化的影响。(2)丁村剖面记录的气候事件与格陵兰冰芯δ^(18)O、黄土高原西部的李家塬剖面以及西风区则克台和塔吉克斯坦剖面均具有很好的对应关系,结合已有研究表明,中国季风区的气候快速波动幅度受西风和东亚夏季风共同影响。展开更多
Here we discussed rapid response of the cave temperature and vegetation to the four Dansgaard-Oeschger cold and warm cycles during 50-40 kaBP based on results of oxygen and carbon stable isotopic compositions from a s...Here we discussed rapid response of the cave temperature and vegetation to the four Dansgaard-Oeschger cold and warm cycles during 50-40 kaBP based on results of oxygen and carbon stable isotopic compositions from a stalagmite in Tangshan, Nanjing. It is found that the amount of C3 vegetation relative to C4-type declines during the D-O warm events, indicating the decrease of the effective mete-oric precipitation. Compared with O-isotope records of the Greenland ice core, the stalagmite record displays a very similar pattern to Greenland ice core record over the dec-ade-century time scale, suggesting that the changes of the East Asian monsoon climate are in accordance with the high-latitude polar climate in the short-term time scale. The age of the ice-rafted H5 event in the stalagmite record, how-ever, preceded that of Greenland ice cores by 2 ka. This out of phase between the remote areas cannot be yet proven be-cause the two time scales were determined from different dating methods.展开更多
Our research group have investigated chronology and sedimentology of terrestrialsediments including loess-paleosols sediments over the last 75 ka at Lanzhou, northwestern China,and over the last 45ka at Tokyo, central...Our research group have investigated chronology and sedimentology of terrestrialsediments including loess-paleosols sediments over the last 75 ka at Lanzhou, northwestern China,and over the last 45ka at Tokyo, central Japan. Based on chronology of high resolution dating ofESR, TL, and IRSL and tephrochronology in these sediments, we investigated to reconstructactivities of Asian summer and winter paleomonsoons by using magnetic susceptibility, colorreflectance and eolian dust concentrations over the last 75ka. Relations between standard curves ofdelta <sup>18</sup>O in GISP2 and color reflectance in loess-paleosol sediments of Linxia over last 140 kashows that color reflectances are good proxy records indicating Asian summer paleomonsoonactivity in time and are closely related to standard curve of delta <sup>18</sup>O in GRIP since the lastinterglacial. Also, relations between standard curve of delta <sup>18</sup>O in GISP2 and eolian dustconcentrations over the last 75 ka at Lanzhou shows the Asian winter paleomonsoon activitieshave coincided with climatic changes in North Atlantic by GISP2 ice cores, and suggests thatresponse of winter monsoon was rapid in global cooling stages, but slow in warming stage. Otherresults of our research in terrestrial sediments show as follows; 1) Horizons of Heinrich eventsfrom H1 to H4 in loess-paleosol sequences at Lanzhou. 2) Magnetic susceptibility and MSfrequency dependent are possible to be available as proxy records for pedogenesis of tile KantoLoam in Japan. 3) 8.2ka cooling event was recognized in Holocene loess-paleosol sequences atLanzhou.展开更多
文摘对临汾盆地丁村剖面进行光释光测年,利用粒度年龄模型重建该地区的年代序列,对比分析粒度、频率磁化率和色度等气候代用指标,旨在反映千年尺度气候突变事件在临汾盆地的表现和区域性特征,揭示了东亚季风区末次冰期以来的气候不稳定性与北大西洋地区存在的联系。结果表明:(1)丁村剖面中值粒径和频率磁化率曲线清晰地记录了80~20 ka BP间的5次Heinrich事件和19次Dansgaard-Oeschger(D-O)旋回,其中,H2和H6事件变化幅度最大,信号变化最明显,H5事件次之,H3和H4事件最小,反映了该地气候不仅受大尺度范围气候变化的控制,还受区域气候变化的影响。(2)丁村剖面记录的气候事件与格陵兰冰芯δ^(18)O、黄土高原西部的李家塬剖面以及西风区则克台和塔吉克斯坦剖面均具有很好的对应关系,结合已有研究表明,中国季风区的气候快速波动幅度受西风和东亚夏季风共同影响。
基金This work was supported by the National Natural Science Foundation of China (Grant No. 49972055).
文摘Here we discussed rapid response of the cave temperature and vegetation to the four Dansgaard-Oeschger cold and warm cycles during 50-40 kaBP based on results of oxygen and carbon stable isotopic compositions from a stalagmite in Tangshan, Nanjing. It is found that the amount of C3 vegetation relative to C4-type declines during the D-O warm events, indicating the decrease of the effective mete-oric precipitation. Compared with O-isotope records of the Greenland ice core, the stalagmite record displays a very similar pattern to Greenland ice core record over the dec-ade-century time scale, suggesting that the changes of the East Asian monsoon climate are in accordance with the high-latitude polar climate in the short-term time scale. The age of the ice-rafted H5 event in the stalagmite record, how-ever, preceded that of Greenland ice cores by 2 ka. This out of phase between the remote areas cannot be yet proven be-cause the two time scales were determined from different dating methods.
文摘Our research group have investigated chronology and sedimentology of terrestrialsediments including loess-paleosols sediments over the last 75 ka at Lanzhou, northwestern China,and over the last 45ka at Tokyo, central Japan. Based on chronology of high resolution dating ofESR, TL, and IRSL and tephrochronology in these sediments, we investigated to reconstructactivities of Asian summer and winter paleomonsoons by using magnetic susceptibility, colorreflectance and eolian dust concentrations over the last 75ka. Relations between standard curves ofdelta <sup>18</sup>O in GISP2 and color reflectance in loess-paleosol sediments of Linxia over last 140 kashows that color reflectances are good proxy records indicating Asian summer paleomonsoonactivity in time and are closely related to standard curve of delta <sup>18</sup>O in GRIP since the lastinterglacial. Also, relations between standard curve of delta <sup>18</sup>O in GISP2 and eolian dustconcentrations over the last 75 ka at Lanzhou shows the Asian winter paleomonsoon activitieshave coincided with climatic changes in North Atlantic by GISP2 ice cores, and suggests thatresponse of winter monsoon was rapid in global cooling stages, but slow in warming stage. Otherresults of our research in terrestrial sediments show as follows; 1) Horizons of Heinrich eventsfrom H1 to H4 in loess-paleosol sequences at Lanzhou. 2) Magnetic susceptibility and MSfrequency dependent are possible to be available as proxy records for pedogenesis of tile KantoLoam in Japan. 3) 8.2ka cooling event was recognized in Holocene loess-paleosol sequences atLanzhou.