陕西地洞河高分辨率石笋记录的DO18季风增强事件  

Intensified East Asian summer monsoon during the interval of DO18:Recorded in a high resolution,absolute-dated stalagmite from Didonghe,Shaanxi,Central China

作　　者：翟秀敏 孔兴功[1,2,3] 张远海[4] 张敬伟 王权[5] 邵庆丰 张振球 Zhai Xiumin;Kong Xinggong;Zhang Yuanhai;Zhang Jingwei;Wang Quan;Shao Qingfeng;Zhang Zhenqiu(School of Geography,Nanjing Normal University,Nanjing 210023,Jiangsu;Key Laboratory of Virtual Geographic Environment(Nanjing Normal University),Ministry of Education,Nanjing 210023,Jiangsu;Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application,Nanjing 210023,Jiangsu;Key Laboratory of Karst Dynamics,Ministry of Natural Resources&Guangxi Zhuang Autonomous Region,Institute of Karst Geology,Chinese Academy of Geological Sciences,Guilin 541004,Guangxi;Key Laboratory of Surface Process and Environment Remote Sensing in the Three Gorges Reservoir Area,School of Geography and Tourism,Chongqing Normal University,Chongqing 401331)

机构地区：[1]南京师范大学地理科学学院,江苏南京210023 [2]虚拟地理环境教育部重点实验室(南京师范大学),江苏南京210023 [3]江苏省地理信息资源开发与利用协同创新中心,江苏南京210023 [4]中国地质科学院岩溶地质研究所,自然资源部/广西岩溶动力学重点实验室,广西桂林541004 [5]重庆师范大学地理与旅游学院,三峡库区地表过程与环境遥感重庆市重点实验室,重庆401331

出　　处：《第四纪研究》2020年第4期886-897,共12页Quaternary Sciences

基　　金：国家自然科学基金面上项目(批准号:41672164);国家自然科学基金重点国际合作项目(批准号:41420104002);中国地质科学院岩溶地质研究所所长基金项目(批准号:2014005和2016011)共同资助。

摘　　要：千年尺度事件的结构特征和区域响应是理解和认识冰期气候变化及动力机制的关键.本文基于陕西汉中宁强县地洞河一支长417 mm石笋DDH1的11个U-Th年代和417个氧同位素(δ^18O)数据,重建了末次冰期(64.8~33.2 ka B.P.)亚洲季风演化历史.石笋 δ^18O记录在64.7±0.2 ka B.P.和59.3±0.1 ka B.P.快速负偏,分别指示了DO18事件的开始和H6事件的结束.在DO18事件结束过程,石笋 δ^18O记录在64.0~60.4 ka B.P.持续正偏,振幅达2.9‰,反应季风逐渐减弱,但未出现明显转型阶段.其总体形态与大西洋Cariaco盆地岩芯反射率、南极冰芯的记录较为一致,但是不同于格陵兰冰芯的记录.因地洞河所处青藏高原、 秦岭叠加影响的区域,纬度和地形的双重影响使得其石笋 δ^18O记录较其他地区偏负,振荡幅度更大.因地形阻挡了高纬信号,使得低纬甚至南半球的信号突现出来,ITCZ的移动、南半球温度和水汽潜热的释放作用在这一区域尤为显著.Shaanxi Didonghe is located at the southern slope of Qinling Mountains,and the climate here is mainly controlled by monsoon systems.The blocking of Qinling Mountains and Tibetan Plateau arises different contribution rate of high and low latitude influence,so it makes typical millennial scale events recorded in this region.We collected a stalagmite about 417 mm long from Didonghe Cave(32°40'45″N,106°32'25″E;1262 m a.s.l.),Ningqiang County,southern region of Shaanxi Province.Mean annual precipitation here is 1100 mm and 70%precipitation falls in May to August.11 subsamples were drilled with 0.9 mm dental burs along the central grow axis and dated with U-series method by ICP-MS on a Fisher Thermo-Neptune spectrometer at Nanjing Normal University Isotope Laboratory.417 subsamples were drilled with 0.5 mm diameter carbide dental burs along the grow axis for stable isotope analysis.All this work was finished by Finnigan MAT 253 mass spectrometer at Nanjing Normal University Isotope Laboratory.Based on the lamina chronology and 417 calciteδ^18O datas for DDH1,a detail of ASM from 64.8 ka B.P.to 33.2 ka B.P.was reconstructed.The results indicated that the grow rate varies from 4.89μm/a to 27.00μm/a,the slowest grow stage is in 44.94~53.33 ka B.P.Three weak monsoon events H4,H5a and H6 were recorded.However the weak monsoon event H5 was not completely traced.During 64.7±0.2 ka B.P.,the calciteδ^18O values decreased rapidly about 2‰,indicating an abrupt strengthening in Asia summer monsoon,which is associated with Greenland warming at the onset of DO18.Since 64.0±0.1 ka B.P.,the calciteδ^18O values began to increase about 2.9‰and this trend sustained near four thousand years.This results suggest that the weakening stage of summer monsoon in stalagmite DDH1 far exceeds that in Greenland ice core record.Other cave sediments show that it has a transition stage during 62.2~62.6 ka B.P.But the increased trend ofδ^18O values in DDH1 is still in one line without typical variations.The onset of DO18 in DDH1 is si

关 键 词：地洞河 石笋 DO18事件 H6事件 东亚夏季风 氧同位素 

分 类 号：P597.2[天文地球—地球化学] P532[天文地球—地质学]