摘要
选取陆相湖盆泥河湾盆地的郝家台和东谷坨两剖面 ,共取样 2 86块 ,研究沉积物磁组构参数特征及其环境意义。结果表明 ,沉积物磁组构参数的变化与沉积物粒度参数、磁化率的变化密切相关 ,蕴含着环境变化的信息。磁化率各向异性度 (P)、磁线理 (L )、沉积物磁化率的高值和细粒物质含量的低值指示湖水平面下降 ,气候较为干燥 ;相反 ,则说明湖水平面上升 ,气候较为湿润。据此 ,将泥河湾盆地沉积过程中湖水平面的变化过程划分为 2个大的阶段 ,14个次级阶段。阶段 变化周期较长 ,而阶段 周期则较短 ,可能是由不同的气候周期所控制。而磁化率椭球体最大主轴的方向指示了盆地古水流方向 ,主轴倾角的变化说明了沉积过程是否异常。
samples were collected from Haojiatai and Donggutuo sections in the Nihewan Basin to study the properties of magnetic anisotropy(AMS)and its environmental significance based on the fieldwork.The results show minima(maxima) in anisotropic magnitude(P),lineation(l)and magnetic susceptibility,and low(high)fraction of fine grain sediments coincides with high(low)lake level,warm(cold,dry)periods and retrogradation (progradation) of large detritus.The history of lake level change can be divided into two stages with fourteen substages.The first stage is a long cycle,and the second one is shorter and may be controlled by various climatic periods.The maximum axis of AMS spheroid is paralell to the direction of paleocurrent,and the inclination changes of maximum axis and minimum axis indicate whether or not the deposit is abnormal.
出处
《海洋地质与第四纪地质》
CSCD
北大核心
2000年第3期43-52,共10页
Marine Geology & Quaternary Geology
基金
国家自然科学基金资助项目!( 4 9772 13 9)
关键词
磁组构
沉积物粒度
泥河湾盆地
陆相
断陷湖盆
magnetic anisotropy(AMS)
sediment grain size
paleocurrent
lake level
Nihewan Basin
