钙质碎屑对热带海滩砂粒度参数的影响分析

Influence of Calcareous Fractions on the Grain Size of Tropical Beach Sediment

钙质碳酸盐碎屑是热带海滩沉积物的重要组成部分,其物理特性与海滩中的石英颗粒差异明显。对海南岛东部文昌铜鼓角两侧海湾海滩砂样采用除钙和不除钙两种预处理方法,使用Mastersizer2000激光粒度仪和筛析法进行粒度分析,结果表明:除钙以后粒度频率曲线主体朝细偏,但在粒度频率曲线细尾(4～9)会新增一小峰;去钙前后粒度参数存在明显的线性相关,平均粒径、分选系数和偏态的相关系数依次降低;粒度参数的组合变化以"平均粒径变细、分选系数变好、偏态朝细偏"为主,但仍存在其他的组合变化;在对类似于铜鼓岭周边环境的海滩进行沉积物粒度分析及动力环境研究时,需要了解钙质碎屑含量和颗粒组成。

Calcareous clastics in the tropical beaches are important fractions,which differ from the silicic constituents in the physical character.The beach sediments are chosen to study on the influence of calcareous clastics on the particle grain size distribution through different pre-treatment procedures.After dissolving the calcareous clastics by hydrochloric acid,the main part of particle size distribution curve will be more peaky and move to the fine end.Because the calcareous clastics cement some finer terrigenous particles in the bodies,the dissolution may make the cemented finer particles（4～9） mix with silicic clastics in sediments.After removing the finer particles（4～9）,the parameters of grain size of the insoluble residues show good correlations with the parameters of mixing sediment.The correlation coefficients of mean,sorting,skewness are 0.934,0.890,0.813.For more than 50% samples,the insoluble silicic sands are more fine,better sorted and more finely skew than the total samples.Because of great variability in the shape and species of calcareous clastics in the beach sands,knowing of the species and content of calcareous clastics is necessary to understand the grain-size parameters and studying the dynamic environment of beaches similar to those around Tongguling.