|
|||||
|
|
| 石英光释光测年揭示的晚第四纪毛乌素沙地演化 | |
| 引用本文： | 何忠,周杰,赖忠平,杨林海,隆浩,梁剑鸣.石英光释光测年揭示的晚第四纪毛乌素沙地演化[J].第四纪研究,2009,29(4):744-754. |
| 作者姓名： | 何忠 周杰 赖忠平 杨林海 隆浩 梁剑鸣 |
| 作者单位： | 1. 中国科学院地球环境研究所黄土与第四纪地质国家重点实验室,西安,710075;中国科学院青海盐湖研究所盐湖资源与化学院重点实验室,西宁,810008;中国科学院研究乍院,北京,100049 2. 中国科学院地球环境研究所黄土与第四纪地质国家重点实验室,西安,710075 3. 中国科学院青海盐湖研究所盐湖资源与化学院重点实验室,西宁,810008 4. 中国科学院地球环境研究所黄土与第四纪地质国家重点实验室,西安,710075;中国科学院研究乍院,北京,100049 5. 中国科学院青海盐湖研究所盐湖资源与化学院重点实验室,西宁,810008;中国科学院研究乍院,北京,100049 |
| 基金项目： | 中国科学院地球环境研究所黄土与第四纪地质国家莺点实验室自主部署项目，国家自然科学基金，中国科学院青海盐湖研究所赖忠平百人计划项目 |
| 摘 要： | 本研究利用石英光释光测年的单片再生法(Singlealiquot Regenerativedose Protocol，简称SAR)对毛乌素沙地内部西北－东南方向5个风成砂－砂质古土壤剖面进行了年代测定，结合年代框架和剖面沉积相、磁化率及粒度特征探讨了晚第四纪以来毛乌素沙地演化和气候变化。研究表明毛乌素沙地在晚第四纪以来经历了多次沙地固定与活化的交替演化： 距今91.0ka,71.0ka,48.0ka,22.0ka,11.6ka,5.0ka,1.1ka,1.0ka和0.4ka前后风成砂沉积，沙地活化，指示气候干旱，植被覆盖度低； 在距今65ka和全新世适宜期(8.5～5.0ka)，沙地固定成壤，砂质古土壤发育，指示气候湿润。另外，剖面中风成砂层数变多、厚度增加、粒径变粗指示了晚第四纪以来毛乌素沙地干旱化趋势加强。 |
| 关 键 词： | 毛乌素沙地 晚第四纪 石英光释光测年 沙漠演化 气候变化 |
LATE PLEISTOCENE SAND DUNE DEVELOPMENT AND CLIMATIC CHANGES IN THE MU US DESERT,CHINA BASED ON LUMINESCENCE D |
|
| He Zhong,Zhou Jie,Lai Zhongping,Yang Linhai,Long Hao,Liang Jianming.LATE PLEISTOCENE SAND DUNE DEVELOPMENT AND CLIMATIC CHANGES IN THE MU US DESERT,CHINA BASED ON LUMINESCENCE D[J].Quaternary Sciences,2009,29(4):744-754. | |
| Authors: | He Zhong Zhou Jie Lai Zhongping Yang Linhai Long Hao Liang Jianming |
| Institution: | State Key Laboratory of Loess and Quaternary Geology|Institute of Earth Environment|Chinese Academy of Sciences|Xi′an 710075|Luminescence Dating Group|Key Laboratory of Salt Lake Resources and Chemistry|Qinghai Institute of Salt Lakes|Chinese Academy Sciences|Xining 810008|Graduate University of Chinese Academy of Sciences|Beijing 100049 |
| Abstract: | The Mu Us Desert,located in the northwestern fringe of the East Asian monsoon region,is sensitive to climate variations.The desert is characterized by mobile,semi-fixed and fixed sand dunes.At present,the Mu Us Desert is a mosaic of partially to fully active small transverse ridge dunes and large stable sand sheets,most of the dunes in the Mu Us Desert are transverse dunes aligned northeast-southwes,reflecting the regional pattern of sand-moving winds controlled by the cold and dry northwest winter monsoon.Due to its high deposition rates and high sensitivity to climate change,alternating units of dune sands and sandy paleosols in the Mu Us Desert recorded multiple episodes of dune construction and stabilization,in response to strengthening-weakening fluctuations of the East Asian monsoon.However,the aeolian sequences in the desert are often episodically interupted,seen as unconformities,non-aeolian deposition,and mixing of sediments,caused by strong wind erosions.Difficulties for compilation of a continueous sedimentary sequence can be overcome by dating sand dune activities at multiple sites,ultimately producing a high-resolution record of sand dune development and climatic change history.Chronological control is crucial in such reconstructions.Desert evolution and climatic change of high resolution in the Mu Us Desert are still poorly understood in part due to limited numerical dating results.In order to further examine the Late Pleistocene sand dune development and climatic changes in this region,five sand dune sections along a northwest-southeast transect in the Mu Us Desert were investigated and sampled.The chronological framework was constructed by dating 19 samples using quartz optically stimulated luminescence(OSL)and single aliquot regenerative-dose(SAR)protocol.A dose recovery test and a preheat plateau showed that the SAR protocol is appropriate for equivalent dose (De)determination for the samples under study.The concentrations of uranium,thorium and potassium were measured by neutron activation analysis.Magnetic susceptibility was measured on a mass of 10g of ground sediment with a Bartington MS2-B Magnetic Susceptibility Meter.The grain size was determined using a Mastersizer-S laser analyzer with(NaPO3)6 as dispersing agent after pretreatment with 10% HCl and 10% H2O2 to remove secondary carbonates and organic material respectively.Combined with lithologic stratigraphy,grain size,magnetic susceptibility and the luminescence chronology obtained,the sand dune development and climatic changes in the Mu Us Desert during the Late Pleistocene are discussed.Aeolian sand layers with wind-ripple lamination imply lower effective moisture,low vegetation cover and sand dune mobilization.The sandy paleosols represent higher effective moisture,higher vegetation cover and weak aeolian activity.Our results indicate that the Mu Us desert experienced multiple alternations of mobile and fixed episodes:the sand was mobilized approximately at 91.0ka,71.0ka,48.0ka,22.Oka,11.6ka,5.0ka,1.1 ka,1.0ka,0.4ka,and was fixed approximately at 65 ka and Holocene optimum period(8.5～5.0ka).The more and thicker sand layers and increasing coarsening of grain size suggests an increased aridity trend in the Late Pleistocene.More dating work is required in order to further reconstruct high-resolution records of aeolian development in the Mu Us Desert. |
| Keywords: | Mu Us Desert Late Quaternary Luminescence dating sand dune development climatic changes |
| 本文献已被 万方数据 等数据库收录！ | |
| 点击此处可从《第四纪研究》浏览原始摘要信息 | |
| 点击此处可从《第四纪研究》下载免费的PDF全文 | |