三门峡盆地晚新生代沉积物磁性载体类型  

TYPES OF MAGNETIC CARRIERS IN LATE CENOZOIC SEDIMENTS IN SANMENXIA BASIN,NORTHERN CENTRAL CHINA

作　　者：李万伦[1] 陈杰[1] 范俊喜[1] 卢演俦[1] 

机构地区：[1]中国地震局地质研究所,北京100029

出　　处：《地球物理学报》2001年第4期520-527,共8页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目 ( 49732 0 90 ;4 96 0 2 0 36 )

摘　　要：对三门峡盆地晚新生代沉积岩样品进行岩石磁学研究 ,通过三轴饱和等温剩磁和剩磁矫顽力实验、交变退磁和热退磁实验及磁化率测定 ,发现黄土 -古土壤、河湖相灰绿层和冲洪积层 3种不同岩性的磁载体存在显著差异 .即黄土 -古土壤以磁铁矿为主 ,赤铁矿和磁赤铁矿很少 ;河湖相灰绿色沉积磁性矿物含量较低 ,主要为赤铁矿和磁铁矿 ,但磁铁矿较多 ,此外还有一些不稳定磁性矿物 (如针铁矿、菱铁矿等 ) ;冲洪积物以磁铁矿和赤铁矿为主 。Study of rock magnetism is performed on the samples from the late Cenozoic sediments in the Sanmenxia basin,northern central China. Seventeen representative samples are selected to conduct SIRM,remanence coercivity,susceptibility,alternating field and/or thermal demagnetization experiments. It is discovered that there are quite different magnetic carriers among loess palaeosol,lacustrine fluvial gray green deposits and brownish red pluvial alluvial sediments. The magnetic carriers of loess palaeosol is dominanted by magnetite,with only very a little hematite and maghemite. Gray green lacustrine fluvial deposits contain less amount of ferromagnetic minerals mainly including hematite and magnetite,but generaly magnetite is more than hematite,besides some unstable minerals,such as goethite and possiblly siderite. Pluvial alluvial sediments also have magnetite and hematite,but magnetite is comparatively more. [

关 键 词：三门峡盆地 岩石磁学 磁性载体类型 新生代 天然剩磁 沉积物 成因机制 

分 类 号：P318.4[天文地球—固体地球物理学]