黄土磁化率对千年-百年尺度气候事件的记录及其古气候意义  

Millennial and centennial time scaleclimate change recorded by Chinese loess magnetic susceptibility and its paleoclimatic implications

作　　者：徐新文 赵庆 邱海军[1] XU Xinwen;ZHAO Qing;QIU Haijun(Shaanxi Key Laboratory of Earth Surface System and Environmental Carrying Capacity,College of Urban and Environmental Sciences,Northwest University,Xi′an 710127,China;College of Economics and Management,Xi′an University of Posts&Telecommunications,Xi′an 710121,China)

机构地区：[1]西北大学陕西省地表系统与环境承载力重点实验室/城市与环境学院,陕西西安710127 [2]西安邮电大学经济与管理学院,陕西西安710121

出　　处：《西北大学学报（自然科学版）》2020年第3期411-419,共9页Journal of Northwest University（Natural Science Edition）

基　　金：国家自然科学基金资助项目(41402151,41572164);黄土与第四纪地质国家重点实验室开放基金资助项目(SKLLQG1218)。

摘　　要：中国黄土高原的黄土-古土壤风尘堆积序列具有粒度细、沉积速率高和连续性好等特征,是古气候学研究的重要组成部分。黄土沉积物在轨道尺度上与全球气候关系密切,可以记录千年-百年尺度的快速气候事件。中国黄土古气候学取得的核心成果之一,就是磁化率可以作为东亚夏季风替代性指标,然而,磁化率在古气候研究中存在多解性,导致其在高分辨率研究中应用较少。文中选择黄土高原的赵家川和巴谢剖面磁化率数据,通过与格陵兰冰心和中国石笋等高分辨率古气候记录进行对比,发现赵家川剖面磁化率记录了4次Heinrich事件,巴谢剖面磁化率记录了全新世以来新仙女木、9.2 ka和4.2 ka 3次气候快速恶化事件。通过对比分析巴谢剖面磁化率记录的3次快速气候事件及其可能的驱动因素,认为太阳辐射减弱可能是主要因素。The thick and continuous aeolian loess sequences from Chinese Loess Plateau(CLP)were ideal research materials for paleoclimate research.The Chinese loess sequence recorded orbital scaleclimate change excellently that could be compared well with ocean and ice core record.And it is also applied in studies of millennial and centennial time scale climate change.Magnetic susceptibility(MS)is an excellent indicator for East Asian Summer Monsoon(EASM)intensity in loess paleoclimate studies.However,it is seldom applied in millennial and centennial time scale climate change in loess paleoclimate studies because of its multipleinterpretations.In this paper,the high resolution MS record in Zhaojiachuan(ZJC)and Baxie(BX)loess profile were studied to discuss the evidence of millennial and centennial time scale climate change.MS in ZJC shows four major decrease that greater than 10×10^-8 m^3·kg^-1 in the past 60 to 10 ka.The age of these decreases in MS was 51.43 ka,40.98 ka,31.66 ka and 21.35 ka,respectively.The age dependent decrement of MS can make these changes more visible.MS in BX shows two abrupt decreases at about 12.16 ka and 5.33 ka.In addition,it also exhibits a distinct trough at about 9.3 ka.Compared withδ18 O record in Greenland ice core and Chinese stalagmite,four Heinrich events(H 5,H 4,H 3,H 2)were identified in ZJC MS record.BX MS recorded three abrupt climate changes related to Younger Dryas(YD),9.2 ka and 4.2 ka events.Comparing to the absent event happened at 8.2 ka,the most effect of these three events in CLP was the abrupt and large amplitude decrease of precipitation other than temperature.The similar behaviors of these three events in MS record in BX profile indicate they have similar driving factor.Compared to 8.2 ka event,the decrease in solar activity was the common possible driving factor for YD,9.2 ka and 4.2 ka events,and should be the most possible driving factor.

关 键 词：黄土 磁化率 千年-百年气候事件 

分 类 号：P318.44[天文地球—固体地球物理学]