一种适用于微体古生物沉积动力分析的沉积物粒径指数及其应用例证

A New Sediment Grain Size Index Designed for Sedimentological Study of Microfossils ——With Demonstrations of Foraminifera in Jiangsu Coast, China

微体古生物的沉积动力分析可提取出比单纯的微体古生物分析更多更准的古沉积环境信息。本文提出一种称为“沉积物粒径指数（ｇｓｉ）”的半定量参数，适用于微体古生物的沉积动力学分析研究。长江口及苏北辐射沙洲区的有孔虫分析实例表明这种沉积物粒径指数行之有效。

In this paper, a new sediment grain size index, gsi, is proposed as a supplementary time-saving tool of sedimentological analysis of micro-fossils. The gsi is determined according to the grain size rank and composition of sediment at the time of sampling for microfossils. For example, gsis for clay, silt and fine sand are 1.0, 2.0 and 3.0, respctivly, for silty clay, clayey silt are 1.2 and 1.8. The reliability of this semi-quantitative index system has been confirmed by using correlation analysis of actural Md data gained through conventional instrument analysis of 20 sediment samples with their corresiponding gsi data. The correlation coefficient is as high as 0.9312. As demonstration for practical use of gsi, sedimntological foraminiferal analysis was prformed on 90 samples from Yangtze River mouth and Jiangsu coastal zone where taphonomic processes of foraminiferal taphocoeenoses are important. The demonstration indicated the gsi is useful and time-saving for sedimentological study on the base of microfossil.