云南热带亚热带发育于弱磁性砂岩的土壤磁性特征及其环境意义  

Soil Magnetic Characteristics of Weakly Magnetic Sandstones in Tropical and Subtropical Yunnan and Their Environmental Significance

作　　者：陈宇东 李海侠[1] 张小凌[1] 胡金 李刚强 胡静远 Chen Yudong;Li Haixi;Zhang Xiaoling;Hu Jin;Li Gangqiang;Hu Jingyuan(Faculty of Land and Resources Engineering,Kunming University of Science and Technology,Kunming 650093,China;Yuxi Normal University,Yuxi 653100,China)

机构地区：[1]昆明理工大学国土资源工程学院,昆明650093 [2]玉溪师范学院,云南玉溪653100

出　　处：《热带地理》2023年第11期2229-2240,共12页Tropical Geography

基　　金：国家自然科学基金项目“云南红壤磁性增强与有机碳积累的关系及其机理研究”(41664003);云南省教育厅科学研究基金项目“滇中峨山花岗岩体成矿条件分析及遥感找矿预测”(2020J0644);云南省科技计划地方高校联合专项—面上项目“滇中峨山花岗岩体淡色花岗岩成因及成矿关系研究”(202001BA070001-125)。

摘　　要：选取云南不同气候区发育于弱磁性砂岩的土壤剖面,分析磁性差异及其对气候变化的响应,探讨赤铁矿和针铁矿与气候因素的关系。结果表明:1)位于热带亚热带地区的峨山(EF)、普洱(PF)和景洪(F)土壤中亚铁磁性矿物主要为磁赤铁矿和磁铁矿,不完全反铁磁性矿物为针铁矿和赤铁矿。EF土壤中亚铁磁性矿物含量相对较高,PF和F土壤中针铁矿和赤铁矿的含量相对较高;3个研究区均含大量的细粒(超顺磁、单畴等)磁性矿物。2)土壤磁化率与温度和降水无显著相关性,难以作为该区域的气候代用指标。3)赤铁矿和针铁矿比值Hm/Gt和Hm/(Hm+Gt)与温度有良好的对应关系,在指示温度方面有应用潜力。As an important surface ecosystem of the earth,the soil records abundant geological and environmental information.During the formation and development of soil,the magnetic minerals it contains will also change.Therefore,soil magnetism is related to the climatic environment information of the soil formation period and can be used to reconstruct the paleoenvironment.Currently,the research on soil magnetism in temperate semi-arid areas and its corresponding climatic and environmental indicators is relatively mature;however,the climatic and environmental indicators of soil magnetism in tropical and subtropical areas remain controversial and need further research.In this study,magnetic and diffuse reflectance spectroscopy were used to analyze the weathering crust of sandstone in different climatic zones in Yunnan.The results show that:(1)the three selected ferrimagnetic minerals in weathering crust profiles are magnetite and maghemite;the antiferromagnetic minerals are goethite and hematite.The main magnetic-bearing minerals in the soil of EF,PF,and F samples are magnetite and maghemite.The soil of PF and F samples contains relatively more antiferromagnetic minerals,goethite,and hematite,and the meanχfd%values in the three sections are 16.01%,14.58%,and 10.06%,respectively.These results indicate that the three profiles all contain a large number of SP particles,and the ferrimagnetic mineral content in EF samples is much higher than that in PF and F samples.(2)From the perspective of the soil developed on the parent material of sandstone,no obvious correlation between the magnetic susceptibility changes of the three profiles and temperature and precipitation was observed.The magnetic susceptibility applicable to the temperate loess area is difficult to use as a climate proxy index in this region.Temperature and precipitation are not the main factors affecting the changes in magnetic susceptibility of soil,and various factors affect these changes.A large-scale and multi-section comparative study is necessary to evaluat

关 键 词：热带亚热带地区 不同气候带 砂岩风化壳剖面 磁学参数 环境意义 云南 

分 类 号：P532[天文地球—古生物学与地层学]