Size distribution of detrital mineral grains suspended in surface waters of the Yellow Sea and East China sea

Abstract

Anisotropic detrital mineral grains were segregated microscopically from the suspended matter in surface waters of the Yellow Sea and East China Sea. Microscopic grain-size measurements of the anisotropic minerals were carried out for more than 80 slide specimens which are distributed homogeneously in the Yellow Sea and East China Sea. The distribution maps of mean grain size and sorting coefficients indicate that the mean size becomes coarser as one goes offshore, and the sorting coefficients are larger in the southern portion and smaller in the northern portion of this region. The clay-sized minerals in the suspended sediments carried out by the deltaic rivers of the continent were deposited in the nearshore area while coarser silt-sized minerals were suspended in offshore waters. The larger sorting coefficients (standard deviations) in the southern portion may imply that the silt-sized grains of offshore waters contain coarser sand-sized grains. The sand-sized grains may be supplied from offshore Taiwan and the Bashi Channel and transported by the main flow of the Kuroshio current.