沉积物岩芯X光片图像灰度数值及其影响因素

摘要

X-ray radiograph of sedimentary core contains much information,including sedimentary texture,density,structure,etc.We can quickly extract the information of climate and environment changes from sedimentary core by using digital image processing method,witch may be a powerful research tools to exploring high-resolution sedimentary records and palaeo-environment evolution.Based on the matlab software platform,we obtained the X-ray images of the sediment core taken from the subaqueous Yangtze River delta and changed them into digital gray images then for extracting their gray values.Combined with the sediment properties in the core such as grain size parameters,influencing factors of the digital gray values were discussed.The results indicate that the gray values of sediment core are influenced comprehensively by sediment composition,texture and structure,with being dominantly influenced by sediment grain-size.There is a good linear relationship between mean grain-size and gray value.Furthermore,there is a positive correlation between sand,silt and gray value.In contrary,it is of a good negative relationship between clay and gray value.Generally,the X-ray image gray value of sediment core may be an ideal proxy of comprehensive sedimentary records.%沉积体的X光影像包含了沉积物密度、结构、构造等众多信息,对X光影像进行数字图像分析可快速提取这些信息,成为进行沉积记录和古环境演变研究的有力手段。基于长江水下三角洲沉积物岩芯的X光影像,利用Mat-lab软件平台把X光影像转换成数字灰度图像,进而提取了岩芯灰度值;结合该岩芯的粒度等沉积学属性,探讨了灰度图像的影响因素。结果表明：沉积物岩芯的X光图像灰度值是沉积物组成、结构和构造的综合反映,其中粒度对灰度值起到控制性的影响。平均粒径与灰度值之间为良好的线性关系;砂粒级、粉砂粒级含量与灰度之间存在较好的正相关,而黏土粒级含量与灰度存在很好的负相关。沉积物岩芯X光图像的灰度值可以作为该岩芯的粒度的良好替代性指标。