基于湖北省落水洞一支长550 mm石笋的23个^230Th年龄、1099个氧同位素数据,重建了12.96~1.53 ka B.P.时段的平均分辨率为11 a的亚洲夏季风演化序列.该序列记录了在9.2 ka B.P.时存在一个显著的弱季风事件(称为"9.2 ka"事件),&...基于湖北省落水洞一支长550 mm石笋的23个^230Th年龄、1099个氧同位素数据,重建了12.96~1.53 ka B.P.时段的平均分辨率为11 a的亚洲夏季风演化序列.该序列记录了在9.2 ka B.P.时存在一个显著的弱季风事件(称为"9.2 ka"事件),"RAMPFIT"法分析显示:"9.2 ka"事件的持续时间在9.8~9.2 ka B.P.之间,亚洲夏季风在"9.2 ka"事件中表现出开始时缓慢减弱(219 a)、 结束时迅速增强(78 a)的特征,事件内部存在两个次一级的振荡,曲线呈"两谷夹一峰"的不对称"W"型结构特征."9.2 ka"事件受太阳活动和北大西洋淡水注入的共同影响,此时太阳活动减弱,且发生淡水注入事件,导致温盐环流减弱,赤道辐合带南移,促使亚洲夏季风减弱.展开更多
利用湖北神农架利川市玉龙洞一支长约400 mm的石笋(TCL),结合稳定同位素、 微量元素以及灰度等多指标重建了14.4 ka B.P.~2012 A.D.时段十年际分辨率的东亚地区气候与环境变化.该时段内,δ^18O变化范围为-9.5‰^-6.6‰,平均值为-8.48‰...利用湖北神农架利川市玉龙洞一支长约400 mm的石笋(TCL),结合稳定同位素、 微量元素以及灰度等多指标重建了14.4 ka B.P.~2012 A.D.时段十年际分辨率的东亚地区气候与环境变化.该时段内,δ^18O变化范围为-9.5‰^-6.6‰,平均值为-8.48‰.该记录与亚洲季风区同时段其他石笋记录重现性良好,说明石笋δ^18O可以较好地反映轨道至千年尺度的亚洲夏季风强度变化.结合其δ^13C、 微量元素以及灰度重建了多指标气候变化.石笋δ^13C变化范围是-8.2‰^-3.8‰,围绕均值-5.4‰上下波动,主要存在千年尺度振荡,反映了洞穴上覆植被覆盖率和土壤CO2产率的变化.石笋TCL的灰度值、Sr/Ca和Ba/Ca比值与δ^13C值在千年尺度波动上对应关系良好,间接指示了与当地水热条件相关的洞穴水文状况变化.石笋灰度与δ^13C值对应关系良好,间接指示了干湿度或降雨量的变化.石笋中Sr/Ca和Ba/Ca变化的总体趋势基本一致,主要受当地降水量控制下土壤淋滤作用变化的影响.TCLδ^18O序列显示"4.2 ka事件"的起止时间段为4.4~4.1 ka B.P.,整体呈现"缓慢开始,快速结束"的结构特征.此时段其δ^13C值偏正,灰度以及微量元素代用指标趋势均呈现低值,这种不同指标间出现的协同变化,说明当时利川地区降水量减少,局域环境明显偏向干冷.文章推测此次干旱事件的发生是由于大量淡水注入北大西洋,海表温降低,使得赤道辐合带(ITCZ)南移,进而引起北半球中低纬度季风减弱并得以在石笋多指标记录中反映.展开更多
A high-resolution oxygen-isotope record from a thorium-uranium-dated stalagmite from Shanbao Cave at Shennongjia reflects variations in the amount of monsoon precipitation for the period from 11.5 to 2.1 ka (1 ka = 10...A high-resolution oxygen-isotope record from a thorium-uranium-dated stalagmite from Shanbao Cave at Shennongjia reflects variations in the amount of monsoon precipitation for the period from 11.5 to 2.1 ka (1 ka = 1000 cal aBP). Between 11.5 and 9.3 ka, a sharp decrease in δ18O indicates a rapid increase in monsoon precipitation. An interval of generally high monsoon precipitation is observed between 9.3 and 4.4 ka. An arid period has prevailed between 4.4 and 2.1 ka. The long-term trend of Shanbao record appears to follow summer insolation at 33°N latitude. An abrupt decrease in monsoon precipitation around 4.3 ka is synchronous with the collapse of Neolithic culture in central China. This abrupt change could have resulted from the amplifi- cation of the gradually decreased summer insolation by the positive vegetation-atmosphere-aerosol feed- back. The weakened Asian monsoon events were in concert with decreased Greenland temperature dur- ing the early Holocene, centered at 8.2, 8.6, 9.3, 10.2 and 11.0 ka. This correlation suggests that changes in low-latitude monsoon are connected with climate change in high-latitude polar region.展开更多
230Th ages and oxygen isotope data of a stalagmite from Shanbao Cave in Hubei Province characterize thEast Asian Monsoon precipitation from 133 to127 ka. Thdecadal-scale high-resolution δ18O record reveals a detailed...230Th ages and oxygen isotope data of a stalagmite from Shanbao Cave in Hubei Province characterize thEast Asian Monsoon precipitation from 133 to127 ka. Thdecadal-scale high-resolution δ18O record reveals a detailedtransitional process from the Penultimate Glaciation to thLast Interglaciation. As established with 230Th dates, the agof the Termination II is determined to be 129.5±1.0 kaBPwhich supports the Northern Hemisphere insolation as thtriggers for the ice-age cycles. In our δ18O record, the glacialinterglacial fluctuation reaches about 4‰, almost the samlevel as in other Asian Monsoon cave stalagmite δ18O recordThe transition of the glacial/interglacial period in our recordcan be recognized as four stepwise stages, among which, arapid rise of monsoon precipitation follows the stage o“Termination II pause”. The rapid rise is synchronous withthe abrupt change of global methane concentration, whichreflects that an increase in both Asian Monsoon precipitationand tropical wetland plays an important role in the globaclimate changes.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
从 Sanbao 洞的一个石笋氧同位素记录，中国，与 7 230Th 年龄和 355 氧同位素数据建立了，在现在( ka BP )前从 284～240 千年为时期向东方亚洲季风(电动会计记帐机)紧张的连续历史提供 34 ka 的典型错误。这个新记录扩大以前出版...从 Sanbao 洞的一个石笋氧同位素记录，中国，与 7 230Th 年龄和 355 氧同位素数据建立了，在现在( ka BP )前从 284～240 千年为时期向东方亚洲季风(电动会计记帐机)紧张的连续历史提供 34 ka 的典型错误。这个新记录扩大以前出版的石笋 18O 记录回到海洋的氧同位素阶段(MIS ) 8。MIS8 电动会计记帐机记录广泛地跟随导致 orbitally 的曝晒变化并且被至少 6 标点强壮 -- 并且 3 个弱季风的事件。在结束 III (TIII ) 附近的弱季风事件在 257 ka BP， 253 ka BP 和 246 ka BP 被标明日期，并且能清楚地被相关到三冰木排碎片(IRD ) 在北方大西洋的事件。TIII 看起来显示二阶段的冰川的结束进程，类似于 TI 和 TII 的。阶段我被与完整的大气的 CO2 集中和南极温度上升是同时代的几几千年(250244 ka BP ) 的一个弱季风阶段描绘。阶段 II 被很快加强的季风在 244 ka BP 标记，由 CH4 集中和大气的 CO2 集中的快速的增加伴随了。我们的观察支持北半球(NH ) 夏天曝晒触发了的 Milankovitch 理论冰川间冰期的周期。另外，我们的结果建议南部的半球(嘘) 温暖可能在 TIII 便于 AM 的结束。展开更多
文摘利用湖北神农架利川市玉龙洞一支长约400 mm的石笋(TCL),结合稳定同位素、 微量元素以及灰度等多指标重建了14.4 ka B.P.~2012 A.D.时段十年际分辨率的东亚地区气候与环境变化.该时段内,δ^18O变化范围为-9.5‰^-6.6‰,平均值为-8.48‰.该记录与亚洲季风区同时段其他石笋记录重现性良好,说明石笋δ^18O可以较好地反映轨道至千年尺度的亚洲夏季风强度变化.结合其δ^13C、 微量元素以及灰度重建了多指标气候变化.石笋δ^13C变化范围是-8.2‰^-3.8‰,围绕均值-5.4‰上下波动,主要存在千年尺度振荡,反映了洞穴上覆植被覆盖率和土壤CO2产率的变化.石笋TCL的灰度值、Sr/Ca和Ba/Ca比值与δ^13C值在千年尺度波动上对应关系良好,间接指示了与当地水热条件相关的洞穴水文状况变化.石笋灰度与δ^13C值对应关系良好,间接指示了干湿度或降雨量的变化.石笋中Sr/Ca和Ba/Ca变化的总体趋势基本一致,主要受当地降水量控制下土壤淋滤作用变化的影响.TCLδ^18O序列显示"4.2 ka事件"的起止时间段为4.4~4.1 ka B.P.,整体呈现"缓慢开始,快速结束"的结构特征.此时段其δ^13C值偏正,灰度以及微量元素代用指标趋势均呈现低值,这种不同指标间出现的协同变化,说明当时利川地区降水量减少,局域环境明显偏向干冷.文章推测此次干旱事件的发生是由于大量淡水注入北大西洋,海表温降低,使得赤道辐合带(ITCZ)南移,进而引起北半球中低纬度季风减弱并得以在石笋多指标记录中反映.
基金This work was supported by National Science Foundation of China(Grant No.40225007)The Foundation for the Author of National Excellent Doctoral Dissertation of P.R.China(Grant No.200227).
文摘A high-resolution oxygen-isotope record from a thorium-uranium-dated stalagmite from Shanbao Cave at Shennongjia reflects variations in the amount of monsoon precipitation for the period from 11.5 to 2.1 ka (1 ka = 1000 cal aBP). Between 11.5 and 9.3 ka, a sharp decrease in δ18O indicates a rapid increase in monsoon precipitation. An interval of generally high monsoon precipitation is observed between 9.3 and 4.4 ka. An arid period has prevailed between 4.4 and 2.1 ka. The long-term trend of Shanbao record appears to follow summer insolation at 33°N latitude. An abrupt decrease in monsoon precipitation around 4.3 ka is synchronous with the collapse of Neolithic culture in central China. This abrupt change could have resulted from the amplifi- cation of the gradually decreased summer insolation by the positive vegetation-atmosphere-aerosol feed- back. The weakened Asian monsoon events were in concert with decreased Greenland temperature dur- ing the early Holocene, centered at 8.2, 8.6, 9.3, 10.2 and 11.0 ka. This correlation suggests that changes in low-latitude monsoon are connected with climate change in high-latitude polar region.
基金This work was supported by National Excellent Doctoral Dissertation of China(Grant No.200227)the National Outstanding Youth Foundation of China(Grant No,40225007).
文摘230Th ages and oxygen isotope data of a stalagmite from Shanbao Cave in Hubei Province characterize thEast Asian Monsoon precipitation from 133 to127 ka. Thdecadal-scale high-resolution δ18O record reveals a detailedtransitional process from the Penultimate Glaciation to thLast Interglaciation. As established with 230Th dates, the agof the Termination II is determined to be 129.5±1.0 kaBPwhich supports the Northern Hemisphere insolation as thtriggers for the ice-age cycles. In our δ18O record, the glacialinterglacial fluctuation reaches about 4‰, almost the samlevel as in other Asian Monsoon cave stalagmite δ18O recordThe transition of the glacial/interglacial period in our recordcan be recognized as four stepwise stages, among which, arapid rise of monsoon precipitation follows the stage o“Termination II pause”. The rapid rise is synchronous withthe abrupt change of global methane concentration, whichreflects that an increase in both Asian Monsoon precipitationand tropical wetland plays an important role in the globaclimate changes.
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.
基金supported by the National Natural Science Foundation of China (Grant Nos. 40631003 and 40771009) Innovation Project in Graduate Education of Jiangsu Province (Grant No. CX07B-051Z)
文摘从 Sanbao 洞的一个石笋氧同位素记录，中国，与 7 230Th 年龄和 355 氧同位素数据建立了，在现在( ka BP )前从 284～240 千年为时期向东方亚洲季风(电动会计记帐机)紧张的连续历史提供 34 ka 的典型错误。这个新记录扩大以前出版的石笋 18O 记录回到海洋的氧同位素阶段(MIS ) 8。MIS8 电动会计记帐机记录广泛地跟随导致 orbitally 的曝晒变化并且被至少 6 标点强壮 -- 并且 3 个弱季风的事件。在结束 III (TIII ) 附近的弱季风事件在 257 ka BP， 253 ka BP 和 246 ka BP 被标明日期，并且能清楚地被相关到三冰木排碎片(IRD ) 在北方大西洋的事件。TIII 看起来显示二阶段的冰川的结束进程，类似于 TI 和 TII 的。阶段我被与完整的大气的 CO2 集中和南极温度上升是同时代的几几千年(250244 ka BP ) 的一个弱季风阶段描绘。阶段 II 被很快加强的季风在 244 ka BP 标记，由 CH4 集中和大气的 CO2 集中的快速的增加伴随了。我们的观察支持北半球(NH ) 夏天曝晒触发了的 Milankovitch 理论冰川间冰期的周期。另外，我们的结果建议南部的半球(嘘) 温暖可能在 TIII 便于 AM 的结束。
