Oxygen isotope compositions of fine-grained quartz from soils and sediments in Southern Shizuoka, Central Japan

抄録

Origin of the fine-grained quartz in soils and sediments developed on the Pleistocene terrace deposits and volcanic materials in southern Shizuoka, central Japan, was studied in view of the particle-size distribution and oxygen isotope composition of their constituent quartz. Most soil and sediment quartz occurs in the fractions finer than 53 μm in diameter with monomodal particle-size distribution, reflecting the effects of eolian sorting. The particle-size, however, is somewhat larger than that of the long-distance eolian dusts from the inland of the Asian continent (14 to 36 μm vs. 11 to 13 μ m particle-size peak). The oxygen isotope compositions of fine aerosol-size quartz (1-10 μm) separated from these surficial materials range from +16.2 to +18.7‰, by up to 3‰ higher than that of the eolian dusts from inland of the Asian continent (+16‰), and by 0.3 to 1.7‰ lower than that of the local river bed deposits. The data indicate that the quartz in the surficial soils and sediments is a mixture of the continental and local eolian additions.