Granularity analyses of superficial sediments of Sparitina alterniflora flat on south coast of Hangzhou Bay

Using south coast of Hangzhou Bay as a case study,the article researches on the granularity distribution characteristic of superficial sediments on Sparitina alterniflora flat.The results show that the sediments types on the flat are composed of clay-salt,salt,salt-sand and sand-salt.From Hangzhou Bay mouth to inside,median diameter of superficial sediments becomes greater while sorting become fine.From low flat to high flat,median diameter of superficial sediments increases gradually,but sorting becomes worse.The formation of S.alterniflora salt marsh has a great influence on depositional characteristic and evolvement process of topography on tidal flats.