位于青藏高原与黄土高原过渡带的甘肃武都万象洞石笋WXSM51和WXSM52提供了M IS 5(118~79kaB.P.)高分辨率的1δ8O记录。研究表明,万象洞石笋1δ8O值与夏季风强度呈负相关关系,与我国西南部的贵州董歌洞石笋1δ8O记录有良好的对应关系,并...位于青藏高原与黄土高原过渡带的甘肃武都万象洞石笋WXSM51和WXSM52提供了M IS 5(118~79kaB.P.)高分辨率的1δ8O记录。研究表明,万象洞石笋1δ8O值与夏季风强度呈负相关关系,与我国西南部的贵州董歌洞石笋1δ8O记录有良好的对应关系,并与高纬度的格陵兰NGR IP冰芯1δ8O记录和65°N太阳辐射强度有很好的一致性,说明万象洞石笋1δ8O记录了118~79kaB.P.期间亚洲季风强度的变化,同时也说明东亚季风强度的变化和全球气候变化同步,而且主要受控于北半球太阳辐射强度的变化。同时它与地中海碳酸盐记录有很好的相似性,和巴西石笋1δ8O记录在千年尺度上表现出相反的变化趋势,说明东亚季风区、地中海地区以及巴西季风区之间存在密切的联系,指示了南北半球气候在千年尺度上存在“跷跷板”(seesaw)现象。万象洞石笋1δ8O记录的M IS 5b与M IS 5 a突发性转换,与NGR IP冰芯1δ8O记录相似,而与神农架记录存在差异,说明万象洞地区对亚洲季风强度的响应更为敏感。展开更多
Field investigations including lake shoreline measurement and 14 C chronology have been carried out on the Alxa Plateau to better understand the formation and evolution of the high lake levels in northwest China durin...Field investigations including lake shoreline measurement and 14 C chronology have been carried out on the Alxa Plateau to better understand the formation and evolution of the high lake levels in northwest China during the late Pleistocene.Comprehensive field investigations show that there are at least ten shorelines at different elevations at Juyan Lake,at least four on the northwest side of the Jilantai Salt Lake,and nine shorelines and one terrace on the northeast margin of Zhuye Lake.Stratigraphic correlations and chronological evidence indicate that the paleo-lakes have the highest lake levels in Marine Isotope Stage (MIS) 3.Though the optically stimulated luminescence (OSL) results which have been reported by some scholars do not support this view,the fact that the paleo-lakes have the highest lake levels in MIS 3 can not be denied.Differences between OSL and 14 C results from this work might indicate that high lake levels existed on the Alxa Plateau during two different periods.It also suggests that the high lake levels may exist in both MIS 5 and early MIS 3.This paper also provides the basic hydrological information for further water resources research in this arid region.展开更多
末次间冰期(深海氧同位素5阶段,MIS 5,71~128 ka BP)离现代间冰期最近,对其认识有助于预测未来环境,而化石孢粉是恢复古植被与古气候的重要指标。通过对选择出的东亚地区孢粉记录的具有年代数据和孢粉图谱的古植被和气候研究的综合分析...末次间冰期(深海氧同位素5阶段,MIS 5,71~128 ka BP)离现代间冰期最近,对其认识有助于预测未来环境,而化石孢粉是恢复古植被与古气候的重要指标。通过对选择出的东亚地区孢粉记录的具有年代数据和孢粉图谱的古植被和气候研究的综合分析,初步认为:①MIS 5的植被格局可与现代间冰期即全新世的植被格局对比。②各区孢粉记录了MIS 5气候波动,部分地区可划分出5a,5b,5c,5d和5e,存在轨道尺度变化,千年尺度事件较少发现。③东亚季风是影响现代东亚季风区环境的主要因素,但日本可能还受到西风环流和洋流的影响;西风、印度季风和地形是影响青藏高原环境的主要因素。④东亚地区,特别是干旱半干旱区,分辨率较高的孢粉记录的环境变化仍需更深入的研究。展开更多
Research on climate changes between the last interglacial period and Holocene renders a speculation on the tendency of present climate. Fully understanding the nature of the changes will play a significant role in a b...Research on climate changes between the last interglacial period and Holocene renders a speculation on the tendency of present climate. Fully understanding the nature of the changes will play a significant role in a better understanding of global climate change. This work discussed the climate change of the last interglacial period and Holocene in Beijing area to discover the mechanism of local palaeo-climate change. The palaeo-vegetation of the last interglacial period in Xishan Mountain of Beijing was reconstructed by pollen analysis and thermo-luminescence dating to represent the change of palaeo-climate and palaeo-environment. Palaeo-vegetation indicators demonstrated that the climate change of the last interglacial period included 6 stages and was homologous to that reflected by the records from deep sea depositions and polar ice cores, respectively corresponding to Marine Isotope Stage (MIS) 5e, 5d, 5c, 5b, 5a and the interim from MIS5 to MIS4 from the early to the late. Millennial climate abrupt events occurred in MIS 5e, which had an agreement with the records of GRIP. In addition, a climate warming event appeared in the interim from MIS5 to MIS4 and it also was found in other regions of the world. Compared with the vegetation and environment indicators of Holocene in Beijing area, it was found that the vegetation, climate and environment of the last glacial period were better than those of Holocene. The climate abrupt events not only appeared in the last interglacial period and MIS 5e, but also occurred in Holocene, whose mechanism and pattern were analogical. After analyzing the records of millennial climate abrupt change events from this work, Ice Cores and others, it was concluded that climate was instability in the interglacial period.展开更多
Trace metals of Mg, Sr and Ba in a stalagmite (SZ2) collected from Suozi Cave in NE Sichuan, Central China, were analyzed with ICP-AES. The stalagmite was dated to have developed between 120 and 103 ka BP. Results ind...Trace metals of Mg, Sr and Ba in a stalagmite (SZ2) collected from Suozi Cave in NE Sichuan, Central China, were analyzed with ICP-AES. The stalagmite was dated to have developed between 120 and 103 ka BP. Results indicate that the Mg/Ca, Sr/Ca and Ba/Ca ratios of SZ2 varied between (9500-14700) 10 6 , (54-123) 10 6 and (31-82) 10 6 , respectively. The three records displayed significant millennial scale variations, which correlate with changes in past climate and environment. Lower values of Mg/Ca ratios and higher values of Sr/Ca and Ba/Ca ratios of SZ2 occurred during relatively cold-dry marine isotope stage (MIS) 5d, while the opposite trend was observed during relatively warm-humid MIS 5c. Trace metals in speleothems can be affected by distribution coefficients or trace metal concentrations in solutions from which speleothems precipitate. Temperature is suggested to be the dominant controller of Mg/Ca ratios in SZ2, whereas the Sr/Ca and Ba/Ca ratios may have been influenced by surface soil and atmospheric dust activities and prior calcite precipitation in Suozi Cave. Further investigations are warranted as to whether Sr/Ca and Ba/Ca ratios were affected by temperature and growth rate of the speleothem. The shifts of Mg/Ca, Sr/Ca and Ba/Ca records in SZ2 during the transition from MIS 5d to 5c apparently were earlier than the oxygen isotope record ( 18 O) of the same stalagmite. This possibly indicates (1) that atmospheric dust activity (the mechanism affecting SZ2 Sr/Ca and Ba/Ca ratios) is closely related to temperature, and (2) that temperature changes (dominated by solar insolation) precedes change in speleothem 18 O records which are controlled by both summer monsoons and winter temperatures.展开更多
基于黔北三星洞石笋（SX29）9个铀钍年龄和420个氧同位素分析,获得了113.6±0.3-106.2±0.4 ka BP（相对于1950年）10年际分辨率的δ18O时间序列.该石笋δ18O时间序列记录了MIS 5d/5c转换时亚洲夏季风强度变化的突变过程.根据...基于黔北三星洞石笋（SX29）9个铀钍年龄和420个氧同位素分析,获得了113.6±0.3-106.2±0.4 ka BP（相对于1950年）10年际分辨率的δ18O时间序列.该石笋δ18O时间序列记录了MIS 5d/5c转换时亚洲夏季风强度变化的突变过程.根据突变过程中间点的年龄确定MIS5d/5c突变时间为108.1±0.3 ka BP.石笋记录对MIS 5d/5c突变时间的精确标定可以作为MIS 5阶段重要的年龄控制点,用以校正南北极冰芯记录和深海沉积记录的时间标尺.季风MIS5d/5c转换阶段也表现为类似过去4个冰消期的2个阶段变化过程：阶段Ⅰ为夏季风较弱时期,而南极温度缓慢上升;阶段Ⅱ为夏季风快速增强时期,与甲烷浓度突变同步,南极温度则上升至最高值.展开更多
文摘位于青藏高原与黄土高原过渡带的甘肃武都万象洞石笋WXSM51和WXSM52提供了M IS 5(118~79kaB.P.)高分辨率的1δ8O记录。研究表明,万象洞石笋1δ8O值与夏季风强度呈负相关关系,与我国西南部的贵州董歌洞石笋1δ8O记录有良好的对应关系,并与高纬度的格陵兰NGR IP冰芯1δ8O记录和65°N太阳辐射强度有很好的一致性,说明万象洞石笋1δ8O记录了118~79kaB.P.期间亚洲季风强度的变化,同时也说明东亚季风强度的变化和全球气候变化同步,而且主要受控于北半球太阳辐射强度的变化。同时它与地中海碳酸盐记录有很好的相似性,和巴西石笋1δ8O记录在千年尺度上表现出相反的变化趋势,说明东亚季风区、地中海地区以及巴西季风区之间存在密切的联系,指示了南北半球气候在千年尺度上存在“跷跷板”(seesaw)现象。万象洞石笋1δ8O记录的M IS 5b与M IS 5 a突发性转换,与NGR IP冰芯1δ8O记录相似,而与神农架记录存在差异,说明万象洞地区对亚洲季风强度的响应更为敏感。
基金supported by the National Natural Science Foundation of China (50879033,41001116 and 40901021)the Specialized Research Fund for the Doctoral Program of Higher Education (SRFD,20090211110025 and 200807301031)the Fundamental Research Funds for the Central Universities (lzujbky-2010-221)
文摘Field investigations including lake shoreline measurement and 14 C chronology have been carried out on the Alxa Plateau to better understand the formation and evolution of the high lake levels in northwest China during the late Pleistocene.Comprehensive field investigations show that there are at least ten shorelines at different elevations at Juyan Lake,at least four on the northwest side of the Jilantai Salt Lake,and nine shorelines and one terrace on the northeast margin of Zhuye Lake.Stratigraphic correlations and chronological evidence indicate that the paleo-lakes have the highest lake levels in Marine Isotope Stage (MIS) 3.Though the optically stimulated luminescence (OSL) results which have been reported by some scholars do not support this view,the fact that the paleo-lakes have the highest lake levels in MIS 3 can not be denied.Differences between OSL and 14 C results from this work might indicate that high lake levels existed on the Alxa Plateau during two different periods.It also suggests that the high lake levels may exist in both MIS 5 and early MIS 3.This paper also provides the basic hydrological information for further water resources research in this arid region.
文摘Research on climate changes between the last interglacial period and Holocene renders a speculation on the tendency of present climate. Fully understanding the nature of the changes will play a significant role in a better understanding of global climate change. This work discussed the climate change of the last interglacial period and Holocene in Beijing area to discover the mechanism of local palaeo-climate change. The palaeo-vegetation of the last interglacial period in Xishan Mountain of Beijing was reconstructed by pollen analysis and thermo-luminescence dating to represent the change of palaeo-climate and palaeo-environment. Palaeo-vegetation indicators demonstrated that the climate change of the last interglacial period included 6 stages and was homologous to that reflected by the records from deep sea depositions and polar ice cores, respectively corresponding to Marine Isotope Stage (MIS) 5e, 5d, 5c, 5b, 5a and the interim from MIS5 to MIS4 from the early to the late. Millennial climate abrupt events occurred in MIS 5e, which had an agreement with the records of GRIP. In addition, a climate warming event appeared in the interim from MIS5 to MIS4 and it also was found in other regions of the world. Compared with the vegetation and environment indicators of Holocene in Beijing area, it was found that the vegetation, climate and environment of the last glacial period were better than those of Holocene. The climate abrupt events not only appeared in the last interglacial period and MIS 5e, but also occurred in Holocene, whose mechanism and pattern were analogical. After analyzing the records of millennial climate abrupt change events from this work, Ice Cores and others, it was concluded that climate was instability in the interglacial period.
基金supported by theNational Natural Science Foundation of China (40973009 and 40672120)
文摘Trace metals of Mg, Sr and Ba in a stalagmite (SZ2) collected from Suozi Cave in NE Sichuan, Central China, were analyzed with ICP-AES. The stalagmite was dated to have developed between 120 and 103 ka BP. Results indicate that the Mg/Ca, Sr/Ca and Ba/Ca ratios of SZ2 varied between (9500-14700) 10 6 , (54-123) 10 6 and (31-82) 10 6 , respectively. The three records displayed significant millennial scale variations, which correlate with changes in past climate and environment. Lower values of Mg/Ca ratios and higher values of Sr/Ca and Ba/Ca ratios of SZ2 occurred during relatively cold-dry marine isotope stage (MIS) 5d, while the opposite trend was observed during relatively warm-humid MIS 5c. Trace metals in speleothems can be affected by distribution coefficients or trace metal concentrations in solutions from which speleothems precipitate. Temperature is suggested to be the dominant controller of Mg/Ca ratios in SZ2, whereas the Sr/Ca and Ba/Ca ratios may have been influenced by surface soil and atmospheric dust activities and prior calcite precipitation in Suozi Cave. Further investigations are warranted as to whether Sr/Ca and Ba/Ca ratios were affected by temperature and growth rate of the speleothem. The shifts of Mg/Ca, Sr/Ca and Ba/Ca records in SZ2 during the transition from MIS 5d to 5c apparently were earlier than the oxygen isotope record ( 18 O) of the same stalagmite. This possibly indicates (1) that atmospheric dust activity (the mechanism affecting SZ2 Sr/Ca and Ba/Ca ratios) is closely related to temperature, and (2) that temperature changes (dominated by solar insolation) precedes change in speleothem 18 O records which are controlled by both summer monsoons and winter temperatures.
文摘基于黔北三星洞石笋（SX29）9个铀钍年龄和420个氧同位素分析,获得了113.6±0.3-106.2±0.4 ka BP（相对于1950年）10年际分辨率的δ18O时间序列.该石笋δ18O时间序列记录了MIS 5d/5c转换时亚洲夏季风强度变化的突变过程.根据突变过程中间点的年龄确定MIS5d/5c突变时间为108.1±0.3 ka BP.石笋记录对MIS 5d/5c突变时间的精确标定可以作为MIS 5阶段重要的年龄控制点,用以校正南北极冰芯记录和深海沉积记录的时间标尺.季风MIS5d/5c转换阶段也表现为类似过去4个冰消期的2个阶段变化过程：阶段Ⅰ为夏季风较弱时期,而南极温度缓慢上升;阶段Ⅱ为夏季风快速增强时期,与甲烷浓度突变同步,南极温度则上升至最高值.
