南昌市厚田沙地末次冰期风沙沉积的磁化率特征及其环境意义  

Magneticsusceptibility characteristics and environmental significance of the last glacial sandstorm deposition in Houtian sandy land in Nanchang City

作　　者：钟颖 李志文 陈琼[3] 黄小兰 胡海平 孙丽 杨妙文 ZHONG Ying;LI Zhiwen;CHEN Qiong;HUANG Xiaolan;HU Haiping;SUN Li;YANG Miaowen(School of Earth Sciences,East China University of Technology,Nanchang,330013;School of Environmental and Chemical Engineering,Foshan University,Foshan,Guangdong,528225;Institute of Cultural Heritage,Shandong University,Qingdao,Shandong,266237)

机构地区：[1]东华理工大学地球科学学院,南昌330013 [2]佛山科学技术学院环境与化学工程学院,广东佛山528225 [3]山东大学文化遗产研究院,山东青岛266237

出　　处：《地质论评》2024年第4期1366-1376,共11页Geological Review

基　　金：国家自然科学基金资助项目(编号:41571007);山东大学环境与社会考古国际合作联合实验室开放基金资助项目(编号:JoInRLESA202301)的成果。

摘　　要：鄱阳湖滨周围和赣江下游沿岸广泛分布着一系列风成砂山。为了探讨南方风沙沉积的磁化率特征及其环境意义,本研究对鄱阳湖南部之厚田剖面的古风沙沉积进行了光释光测年、磁化率、粒度和重矿物分析。结果表明:(1)沙丘砂层的磁化率整体较低,平均粒径(Mz)较粗,成熟度指数(ZTR)较低而风化指数(HW)较高,说明风化程度较低,形成于冬季风强盛、干燥寒冷的气候条件下;砂质古土壤层的磁化率较高,Mz较细,ZTR指数较高而HW指数较低,说明风化程度较高,形成于冬季风较弱、夏季风较强,温暖湿润的气候环境下。(2)厚田剖面第Ⅰ(77.0~57.1 ka)、Ⅲ(49.7~36.8 ka)、Ⅴ(29.7~14.9 ka)阶段依次对应深海氧同位素的MIS4、MIS3b、MIS2,指示为冷期,冬季风强盛,磁化率较低;第Ⅱ(57.1~49.7 ka)、Ⅳ(36.8~29.7 ka)阶段分别对应MIS3c和MIS3a,指示为暖期,夏季风强盛,磁化率较高。这些气候变化特征与黄土高原渭南剖面、深海氧同位素和中国亚热带洞穴石笋δ^(18)O记录具有良好的对比性。因此认为,磁化率在南方风沙沉积中可以有效揭示气候变化。Objectives:A series of sand hills formed under specific climatic conditions are widely distributed around the Poyang Lake and the lower reaches of the Ganjiang River.Aeolian sand deposits are non-zonal deposits in the subtropical region of southern China.The authors carried out many investigations on the coast of Poyang Lake in the subtropical humid monsoon climate zone,and took the aeolian sand deposition profile of Houtian Sandy Land as the research object to explore the significance of magnetic susceptibility to paleoclimate and the climate change process of the last glacial period in Houtian Sandy Land.Methods:This study carried out Optically Stimulated Luminescence(OSL)dating method,magnetic susceptibility,grain size and heavy mineral analysis of paleoaeolian sand landforms in the Houtian section of southern Poyang Lake.Results:The results of magnetic susceptibility,grain size and heavy mineral characteristics indicate that the formation environment of different sedimentary facies is different.The dune sand layer in the profile has generally low magnetic susceptibility,coarser mean grain size(Mz),lower maturity index(ZTR),and higher weathering index(HW),suggesting low weathering degree under strong winter monsoon,dry,and cold climatic conditions.On the other hand,the sandy paleosol layer exhibits higher magnetic susceptibility,finer Mz,higher ZTR index,and lower HW index,indicating lower weathering degree formed in a warm and humid climate environment with weak winter monsoon and strong summer monsoon.Additionally,theⅠ(77.0~57.1 ka),Ⅲ(49.7~36.8 ka),andⅤ(29.7~14.9 ka)stages of the Houtian section correspond to the MIS4,MIS3 b,and MIS2 stages of deep-sea oxygen isotopes,respectively,signifying a cold period,strong winter monsoon,and low magnetic susceptibility.TheⅡ(57.1~49.7 ka)andⅣ(36.8~29.7 ka)stages correspond to the MIS3c and MIS3a stages,respectively,indicating a warm period with strong summer monsoon and high magnetic susceptibility.Conclusions:The climate change features contrast sharply with

关 键 词：厚田沙地 风沙沉积 磁化率 重矿物 环境变化 

分 类 号：P532[天文地球—古生物学与地层学]