长江中游现代河流沉积物磁组构参数值特征研究  

MAGENTIC FABRIC PARAMETER CHARACTER OF MODERN FLUVIAL DEPOSIT IN THE MIDDLE REACHES OF YANGTZE RIVER

作　　者：张玉芬[1] 李长安[1] 

机构地区：[1]中国地质大学,湖北武汉430074

出　　处：《长江流域资源与环境》2003年第4期370-376,共7页Resources and Environment in the Yangtze Basin

基　　金：国家自然科学基金(40172061);中国地质调查局重大项目(19991230003014)

摘　　要：对长江中游?洲湾一带不同类型河段(平直和弯曲)、不同水文环境(高滩、低滩、心滩)沉积物磁组构参数特征的系统取样、测量和统计分析结果表明:1)平直河段沉积物的磁化率各向异性参数的K、P、F、Fs、T以及E的统计平均值均比弯曲河段处相应磁组构参数值略偏大,而q、L的统计平均值却比弯曲河段河流沉积物的相应磁组构值略偏小;2)平直河段各向异性量值椭球长轴磁偏角方向明显,其与水流作用方向具有很好的一致性,而在弯曲河段各向异性量值椭球长轴磁偏角的方向分散,反映了在弯曲河段处水流具有方向多变的特点;3)从河流高滩、低滩到心滩沉积物的磁化率各向异性参数P、F、T、Fs、E的统计平均值均具有从小逐渐变大,而磁基质颗粒度q、磁线理L却从大逐渐变小的变化趋势。这一特点与溃口、高水位时沉积环境不稳定,水流方向多变的、沉积物分选性差的特点是一致的。研究结果对研究古河道的演化、变迁、古河道的识别确定具有重要的意义。In order to establish magnetic fabric identification marking on the different deposit environment in the area of middle reaches of Yangtze river,we studied the magnetic fabric parameter character of modern fluvial deposits.The result reveals,① In the straight river course,the statistical average value of magnetic susceptibility anisotropy parameter K,P,F,F S ,T and E are larger than those in winding river course.However,the statistical average value q and L are less than those in winding river.② The direction of declination of long axis of anisotropy magnitude ellipse in straight river course is very clear.And it has a good consistent with the direction of flow.However,the direction of declination of long axis of anisotropy magnitude ellipse in winding river course is scattered.It is indicated that the direction of flow is changeable in winding river course.③ From high-flood land,low-flood land to sand-bar in the center of river,the statistic average value of magnetic fabric parameter of deposit P ,F ,T ,F S ,E change slowly from small to large.But magnetic matrix grain degree q and magnetic lineation L have the trend from large to small.This feature is in accord ance with that unstable deposit environment on the case of high water level,changeable direction of flow and worse sorted character of deposit on the case of dam-breaking and high water level.The result of study is significant for the study of evolution ,vicissitudes and identification of ancient river source.

关 键 词：长江中游 河流沉积物 磁组构参数值 水文环境 

分 类 号：P332[天文地球—水文科学]