末次冰期亚洲季风事件对南北高纬气候的响应  

Response of Asian monsoon events to north-south high latitude climate in the Last Glacial period

作　　者：周学琴 陈仕涛[1,2,3] 王真军 杨少华 汪永进 邵庆丰[1,2,3] Zhou Xueqin;Chen Shitao;Wang Zhenjun;Yang Shaohua;Wang Yongjin;Shao Qingfeng(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)

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

出　　处：《第四纪研究》2020年第4期864-876,共13页Quaternary Sciences

基　　金：国家自然科学基金项目(批准号:41572340、41571102和41931178);江苏省高校优势学科建设工程项目(批准号:164320H116)共同资助。

摘　　要：末次冰期千年尺度亚洲季风事件与南北高纬度气候变化的关联一直是第四纪古气候领域中的热点问题.本文基于湖北省落水洞长830 mm的LS23石笋15个230Th年龄和830个 δ^18O数据,重建了28.7~22.2 ka B.P.和87.0~82.9 ka B.P.两个时段内平均分辨率分别为20 a和15 a的亚洲季风变化序列.石笋LS23记录的24.7~23.4 ka B.P.期间的千年尺度亚洲弱季风事件,对应于H2事件(Heinrich 2 Event)和南极暖事件2(Antarctic Isotope Maximum 2,简称AIM2事件).该弱季风事件在24.7~23.4 ka B.P.期间呈缓慢开始、缓慢结束的"V"型结构演化模式,与南极对应暖事件的转型特征基本一致,而与北高纬H2事件呈快速开始、 快速结束的"U"型结构明显不同,表明此时亚洲季风主要受到南高纬气候变化的影响.在84.9~84.8 ka B.P.期间,亚洲季风快速增强,对应于格陵兰冰芯记录的DO21事件(Dansgaard-Oeschger 21 Event)的开始阶段.特别重要的是,在石笋 δ^18O序列中识别出和格陵兰冰芯记录一致的PE事件(Precursor-type Peak Event),这是在南极温度变化中难以发现的,说明此时亚洲季风变化可能主要由北高纬触发.由此推断,末次冰期千年尺度亚洲季风事件与南、北高纬气候的联系受气候背景的影响,冰期(比如H2事件所处的MIS 2阶段(Marine Isotope Stage 2,深海同位素2阶段))季风强度变化主要受到南高纬温度的控制,而间冰期(比如DO21事件所处的MIS 5a阶段)主要受到北高纬的触发.The teleconnection between Asian monsoon and climate change of the northern and southern high latitudes during the last glacial has been widely recorded in the geological archives.However,how the processes of high latitudes affects millennial-scale events of Asian monsoon is an open question.This paper is based on an 830-mm stalagmite from Luoshui Cave,Central China,to establish high resolution climate series of the Asian monsoon.The goal of this paper is to study the teleconnection between Asian monsoon and process of high latitudes during the glacial cycle.LS23 was collected in Luoshui Cave(29°44'N,109°7'E)in Hubei Province,Central China.The altitude of Luoshui Cave is about 975 m.The cave is located in the typical subtropical monsoon region with four distinct seasons.Mean annual temperature around the Luoshui Cave is about 14℃and the annual precipitation is about 1400 mm.The precipitation from May to September accounts for 67%of the total amount,and a period of rainy season is prevailed by the Asian Summer Monsoon.The length of stalagmite LS23 is about 830 mm and hiatus are visually inspected at the depth of 308~310 mm and 610~614 mm on the polished surface.15 sub-samples were collected with a 0.9-mm-diameter carbide dental burs for 230Th dating.The dates were obtained using a multi-collector inductively coupled plasma mass spectrometer(MC-ICP-MS)at Nanjing Normal University and Nanyang Technological University with error of±2σ.The chemical procedures were similar to those described in Shao et al.(2017),Li et al.(2019)and Cheng et al.(2013).For stable isotopic measurements,830 sub-samples were drilled with 1-mm-diameter carbide dental burs per 1 mm of the growth axis.The analysis was conducted on a Finnigan MAT-253 mass spectrometer fitted with a Kied Carbonate Device.Stable isotope measurements were reported to Vienna PeeDee Belemnite(VPDB)and with standardization determined relative to NBS19.Precision ofδ^18O was better than 0.06‰,VPDB,at the 1-sigma level.LS23 grows at the periods from 28.7 ka B.P.

关 键 词：亚洲季风 H2事件 DO21事件 高纬气候变化 不同气候背景 

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