阿勒泰地区表土磁学特性及变化机制研究  

STUDY ON THE MAGNETIC CHARACTERISTICS AND VARIABLE MECHANISM OF SURFACE SOILS IN ALTAY AREA,XINJIANG CHINA

作　　者：张俊辉[1] 夏敦胜[2,3] 张英[2] 刘宇航[2] 

机构地区：[1]宝鸡文理学院灾害监测与机理模拟陕西省重点实验室,宝鸡721006 [2]兰州大学西部环境教育部重点实验室,西部环境与气候变化研究院,兰州730000 [3]中国科学院寒区旱区环境与工程研究所沙漠与沙漠化重点实验室,兰州730000

出　　处：《第四纪研究》2013年第5期889-899,共11页Quaternary Sciences

基　　金：国家重点基础研究发展规划项目(973项目)(批准号:2010CB950204);国家自然科学基金项目(批准号:41071125)共同资助

摘　　要：现代表土的磁学性质反映了物源、成土过程与气候环境之间的重要信息,对认识磁学参数在气候环境研究中的应用有重要意义。干旱区表土的磁学特性表现出极大的复杂性和差异性,为了理解不同气候和环境条件下表土磁学参数的特性、变化机制及控制因素,选择位于新疆北部阿勒泰地区不同景观带的表土样品作为研究对象。通过详细系统的环境磁学分析,并结合X衍射和粒度等方法,结果表明磁性矿物来源相对稳定,磁学性质主要由来自源区的粗颗粒软磁性矿物所主导,χ_(lf)(低频磁化率)和SIRM(饱和等温剩磁)与磁性颗粒表现出正相关的关系,磁性矿物浓度越大,磁畴颗粒越粗;反之,浓度越低,颗粒越细。磁性矿物的浓度和颗粒大小在不同景观带表现出一定的差异,荒漠带表土中磁性矿物的浓度较高,磁畴主要为粗颗粒的PSD(准单畴)+MD(多畴),而其他景观带(森林、灌丛、草原和湿地)矿物浓度明显较低,磁畴也相对较细。相比较,其他景观带表土受后期改造作用比荒漠区强,主要是由于在海拔升高到1300m之后,区域气候环境因素(如气温、降水以及蒸发)发生明显变化,导致强磁性矿物的破坏,土壤矿物浓度和粒径发生变化,磁性降低。成壤作用形成的SP(超顺磁畴)颗粒相对较少。Magnetic characteristics of surface soils can reflect important information of provenance,pedogenesis process and environmental conditions,which are significant for understanding the application of magnetic parameters in the study of paleoclimatic environment.To comprehend the magnetic characteristics,variable mechanism and controlling factors of surface soils in different climate and environmental conditions,mineral magnetic investigation was conducted on surface soils from different landscape zones in Altay arid region.In this area,forty-six surface soil samples are collected（23 samples from harsh desert,9 samples in forest zone,2 samples in shrub forest,6 samples in grass land,2 samples from lake sediments and 4 samples from wetland）and these samples almost cover all the full range of landscapes.The latitude ranges from 44°09＇35.1＂N to 48°49＇40.5＂N, longitude ranges from 86°55＇26.9＂E to 90°52＇25.2＂E and the altitude ranges from about 470m to 2600m.The altitude of the two lake samples are both near 480m. In low altitudes,the samples are collected at an interval of 10-15km while in mountain region the samples are collected according to a vertical gradient interval of 80-100m.By the detailed and systemic analysis of environmental magnetism（e.g：magnetic susceptibility,isothermal remanent magnetization,X-T curves,and so on）and non-magnetic means of X-ray diffraction and grain size analysis,we found that：1）The source of magnetic minerals is relatively stable,magnetic characteristics are mainly controlled by the coarse-grained minerals from origin area; 2）The magnetic susceptibility of desert samples is high,while the magnetic susceptibility of forests,bushwood,high mountain meadow above the desert landscape zone decreases significantly.The magnetic minerals are mainly low-coercivity ferrimagnetic（magnetite and maghemite）and anti-ferromagnetic minerals（hematite）,which contribute to the magnetic susceptibility.The main domains of magnetic minerals are MD（multi-domain）and

关 键 词：表土 磁学特性 粒径 阿勒泰 

分 类 号：P534.63[天文地球—第四纪地质学] P318.4[天文地球—古生物学与地层学]